Lite Machines 110 Operator's Manual

Operator's Guide Acknowledgments

cknowledgments

We thank all of those people who helped make Lite Machines Corporation and the

Model 110™ helicopter possible, including our good friend Paul Klusman. The Model 110 Construction Manual and Operator’s Guide were developed and computer

illustrated by Paul Klusman: engineer, test pilot and helicopter guru. We especially thank Mom and Dad - without their help and constant encouragement we could not have done this.

David and Paul Arlton

Lite Machines Corporation Purdue Research Park 1291 Cumberland Avenue West Lafayette, IN 47906 Tel: (765) 463-0959 Fax: (765) 463-7004 USA

PATENT NOTICE

Most aspects of the Lite Machines Model 110 helicopter including, but not limited to, the main rotor, main rotor blades, tail rotor, tail rotor blades, Arlton Subrotor™ stabilizer, Arlton Gyro™ stabilizer, swashplate, fuselage structure and configuration, radio installation configuration, landing gear, and drivetrainare either patented(U.S. 5305968, 5597138, 5609312, 5628620, 5749540, 5836545, 5879131, 5906476; Australia 681287, 686883; Europe 95918276.7-2312, 95932305.6-2312,

96928019.7; France 0605656; Germany 69221307.4; U.K. 0605656), patent pending or patent applied-for in the United States and in other counties. For information concerning patents and licensing, please contact Lite Machines Corporation.

Revision VP8.2 0699

LITE MACHINES

Operator's Guide TABLE OF CONTENTS

ABLE OF CONTENTS

Model Helicopter Safety

Model Helicopter Safety 1-1

Fuel Safety .................1-1

Flight Safety.................1-2

General Safety ...............1-3

Learning to Fly

Learning to Fly 2-1

Helicopter Controls .............2-1

Training Gear ................2-4

Blade Tracking ...............2-5

Dynamic Balancing .............2-6

Neutral Stability ...............2-6

Stability, Control Power and Climb

Performance ...............2-7

Adjusting Main Rotor Blade Pitch ......2-8

Learning to Hover ..............2-8

Learning the Left Stick ...........2-10

Adjusting the Arlton GyroÔ Stabilizer....2-11

Tail Swing and Revo Mix ..........2-11

Learning the Right Stick...........2-12

Translational Lift ..............2-15

Circles....................2-16

Figure 8’s ..................2-17

Descending from Altitude ..........2-18

Landings ..................2-18

Engine Operation

Engine Operation 3-1

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Fuel Mixture and Compression .......3-1

Breaking-In a New Engine .........3-2

General Operating Considerations .....3-3

Engine Starting Summary..........3-3

Preferred Engine Starting Procedure ....3-4

Alternate Starting Method..........3-7

Adjusting Fuel Mixture and Compression . . 3-9

Operator's Guide TABLE OF CONTENTS

Inspecting SpiraLite Speed Glow Plugs .....3-10

Fuel Contamination ...............3-11

Synthetic Oils ..................3-11

Electric Starter Effect on Glow Plug .......3-12

Engine Trouble-Shooting ............3-13

Zen and the Art of Helicopter Maintenance

Zen and the Art of Helicopter Maintenance 4-1

General Maintenance ..............4-1

Engine Maintenance ..............4-1

Radio Maintenance ...............4-2

Main Rotor Maintenance ............4-2

Tail Rotor and Arlton Gyro Maintenance ....4-3

Power Train Maintenance ............4-3

Field Equipment Maintenance..........4-3

Making Repairs with Fast Glass.........4-3

Making Repairs with CA and Baking Soda . . . 4-4

Fixing a Bent Tail Boom .............4-5

Straightening a Bent Main Shaft ........4-5

How Helicopters Work

How Helicopters Work 5-1

Introduction ...................5-1

Background and History.............5-2

Standard Helicopter Configuration .......5-2

Main Rotor Control ...............5-3

Main Rotor Stability ...............5-6

Retreating-Blade Stall ..............5-7

Anti-Torque Systems ..............5-8

Gyro Stabilizers .................5-8

Specifications, Model 110

Specifications, Model 110 6-1

General .....................6-1

Main Rotor....................6-1

Tail Rotor ....................6-2

Engine/Transmission ..............6-2

LITE MACHINES

Operator's Guide Model Helicopter Safety

odel Helicopter Safety

This section contains important safety information regarding proper handling of model-engine fuel and operation of the Lite Machines Model 110 helicopter.

Fuel Safety

1. Use ONLY commercial fuel developed for model engine use. NEVER USE GASOLINE, DIESEL, OR ANY OTHER FUEL! These fuels will ruin model

engines, and can explode and burn causing injury to YOU and OTHERS.

2. DO NOT OPERATE MODEL ENGINES INDOORS! Hot engine parts and exhaust could ignite carpeting, drapery or furniture. Engine exhaust also contains large amounts of unburned oil that will soil interior furnishings.

3. Never fuel or prime with the glow-plug battery connected to the engine. Sparks from the electrical connection could start a fuel fire.

4. Never fuel, prime, or operate your model while smoking.

5. Store fuel in a cool dry place protected from sunlight and from potential ignition sources (anything burning, or anything that could start a fire if exposed to fuel such as shorting or sparking battery terminals or the furnace in your home).

6. Remove excess fuel from your model with a cloth after refueling or priming. Raw fuel can damage paint and is a potential fire source.

7. Do not store fuel in your model.

8. Fuel is poisonous and can cause death or blindness if swallowed. If swallowed, induce vomiting and call for medical assistance immediately.

9. Fuel is an eye irritant. In case of contact with eyes, flush thoroughly with water.

10. Raw fuel will damage certain types of plastic. Prescription plastic lenses and the clear plastic commonly used on radio transmitter meters will be damaged if exposed to raw fuel (such as droplets sprayed from the engine during starting). Wipe off immediately using spray window cleaner.

IF FIRE SHOULD OCCUR:

1. Model fuel burns with a nearly INVISIBLE FLAME, BE VERY CAREFUL!

2. Use a fire extinguisher, or smother fire with a CLEAN, heavy cloth. If fire persists, GET AWAY! Better to lose the model than risk severe burns.

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Operator's Guide Model Helicopter Safety

Flight Safety

1. ALWAYS WEAR APPROPRIATE EYE PROTECTION WHEN OPERATING YOUR MODEL. Fuel droplets, loose parts, and airborne debris ejected from your

model could cause serious injury or blindness. Select comfortable, well-fitting eye wear with high-impact resistance such as shop glasses. Prescription glasses made of glass are dangerous because they could shatter if struck sharply.

2. ALWAYS WEAR APPROPRIATE HEARING PROTECTION WHEN OPERATING YOUR ENGINE. Many car, airplane and helicopter modelers ignore the sound produced by the engines on their models. High volumes and high frequencies produced by model engines can damage hearing.This damage can be cumulative. Ear-phone and ear-plug style hearing protectors (sold in sporting goods stores in the gun section) are inexpensive and effective at reducing the most damaging and annoying qualities of engine sound. Once your model is started and flying, hearing protection is usually not necessary.

3. NEVER STAND OR PLACE YOUR EYES OR FACE IN-LINE WITH ROTATING MAIN ROTOR OR TAIL ROTOR BLADES. Loose parts or debris thrown outward from rotating rotors could cause injury or blindness.

4. NEVER, EVER FLY NEAR OR OVER PEOPLE. Always keep your model at a safe distance from yourself and spectators.

5. Use only thosemodel engines designed specifically for the Model 110 helicopter. Use of more powerful engines (such as racing engines) is potentially dangerous and will void all warranties.

6. Do not use fuel containing more than 35% nitromethane. The added power and heat of high nitro fuels can damage both the engine and your model.

7. Never allow main rotor speed to exceed 2000 RPM (as by operating with blade pitch set too low, or using a high powered engine with high nitro fuel). Rotor parts could separate from the rotor head and cause serious injury or property damage. Very high speeds can also damage the engine.

8. Fly only atapproved flying fields or inopen areas away frompeople and property. Do not fly in residential areas.

9. Before turning on your radio, ensure that your radio frequency is not already in use. Flying clubs have organized frequency sharing procedures.

10. Range check your radio prior to the first flight of each day. If your range check is lower than normal, do not fly.

11. Prior to the first flight of each day, check all mechanics for smooth, unobstructed operation. Before the main rotors reach flying speed, gently move all flight controls and confirm proper function. Do not fly if anything is out of the ordinary.

12. Check for hidden damage after crashing, and replace any damaged components.

13. Beginners should have the main rotors tracked, and model adjusted for flight by an experienced modeler.

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Operator's Guide Model Helicopter Safety

General Safety

1. Periodically check tightness off all bolts, nuts, set screws and pins. Loose parts

could be ejected from your model causing injury, or causing the model to crash.

2. Replace broken or worn components with original parts only. It is important to

locate and understand the cause of failure (including pilot error) to prevent recurring problems.

3. Never modify any part of the main rotor or tail rotor systems or drive train.

Modifications could lead to part failure.

4. Always replace the main and tail rotor blades in sets if damaged.

5. Do not store your model in direct sunlight. Prolonged exposure to ultraviolet light

can weaken some types of plastics.

6. When flying in very cold conditions be aware that metals and plastics (even

flexible ones) can become brittle and break or shatter.

7. Keep your model, radio and field equipment clean and in good repair. While

cleaning and maintaining your model you can often find and fix potential problems before they occur (such as loose or damaged parts).

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Operator's Guide Learning to Fly

earning to Fly

This section describes the various flight controls of the Lite Machines Model 110 helicopter, and astep by step processfor learning how to fly.Although it is possibleto learn to fly on your own, we suggest finding an experienced modeler to help. An experienced model helicopter pilot can help start and tune the engine, trim out the controls, track the rotor blades and “copilot” your Model 110 helicopter while you are learning to fly. You will learn more quickly, and enjoy the process more with a little tutoring. Computerized flight simulators are also an excellent way to gain flight experience without risking your model.

Model flying clubs are a good source of information, and many have flight instructors. Videos, how-to books and magazines also cover the subject in varying degrees of detail from nervous beginner to pompous expert. If possible, spend time with others involved in the hobby to see what equipment they use and what advice they may have to offer. Notethat “advice” can be highly subjective(especially when it comes toradio controlled model helicopters), so talk toseveral individuals. Also jointhe Academy of Model Aeronautics (AMA). TheAMA provides services to modelers, and insurance in case of accidents or injury.

Helicopter Controls

To fly the Model 110 you must first understand the function of each flight control. Fig. 2-1 illustrates the flight motions produced with the right (cyclic) stick on the transmitter. The right stick tips the rotating main rotor in the direction of the stick motion and controls the direction of horizontal flight. Moving the stick left and right tips the main rotor left and right (like aileron control on an airplane). Moving the stick forward and backward (up and down) tips the main rotor forward and backward (like the elevator control on an airplane).

When first learningto use the right stick, it is helpful to thinkof it linked to an imaginary control stick mounted vertically on top of the main rotor. As you push the transmitter stick forward, you also push the imaginary control stick forward and tip the main rotor forward. Imagine the same for backward, left and right.

Fig. 2-2 shows the effect of moving the left stick on the transmitter. The left stick controls the tailrotor and throttle. Moving the left stick to the leftand right changes the pitch of the tail rotor blades causing the Model 110 to rotate to the left or right (like steering a car). Note that the left stick rotates the NOSE to the left and right. Always concentrate on the NOSE when using the left stick to turn. You will become confused if you watch the tail rotor. As shown in the lower half of Fig. 2-2, moving the left stick up and down increasesor decreases engine speed causing the Model 110 toclimb or descend.

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Operator's Guide Learning to Fly

Note: Fully extend transmitter antenna before flying!

Left cyclic (left roll)

Right cyclic (right roll)

Left cyclic

Right cyclic

Forward cyclic (nose down)

Forward

cyclic

Aft cyclic (nose up)

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Aft cyclic

Figure 2-1.

Operator's Guide Learning to Fly

Note: fully extend transmitter antenna before flying!

Left tail - rotor

Right tail - rotor

(nose moves right) Left tail - rotor (nose moves left)

Right tail - rotor

High throttle

(up)

Low throttle

(down)

Low throttle

Figure 2-2.

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Operator's Guide Learning to Fly

Model airplane fliers commonly hold their transmitter so that only their thumbs touch the transmitter sticks. When flying with thumbs, it is easy to unintentionally mix controls by moving the right stick upward and to the right, and the left stick upward and to the left. To control your helicopter more accurately, hold the control sticks with your thumb and index fingers. It helps to support the transmitter with a neck strap to take the weight off of your hands.

Hint: See the How Helicopters Work section of this Operator’s Guide if you are interested

in more technical information on helicopter controls.

Training Gear

Training gear consists of two light wooden dowels attached to the landing gear with rubber bands as shown in Fig. 2-3. Training gear helps prevent tip-overs, and also slows down control response. Use training gear while learning to hover. Cross two 1/4" x 24" (6mm x 61cm) wood dowels to form an “X”, and attach the dowels with rubber bands at the base of each landing gear strut. Glue Ping-Pong balls to the ends of the dowels with thick CA to prevent the dowels from abruptly catching the ground.

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Attach with rubber-bands

Ping-Pong balls

1/4” x 24” wood dowels

Figure 2-3.

Operator's Guide Learning to Fly

Note: If the dowels are too long or too heavy the Model 110 will appear unstable in flight.

This is caused by the heavy dowels swinging under the fuselage on the thin wire landing gear. Reduce the size or length of the dowels if this happens.

Blade Tracking

For the Model 110 to fly properly, both main rotor blades must operate at the same pitch angle. If they are not at the same angle, one blade will fly higher than the other causing an imbalance and vibration. This vibration absorbs engine power and can damage the helicopter. This section describes a procedure for accurately setting main rotor blade pitch (blade tracking) while the engine is running so that both blades fly at the same level.

Blades in track - no vibration

Blades out of track - noticeable vibration

Low blade:

Pitch angle too low

Tracking tape

High blade:

Pitch angle too high

Figure 2-4.

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Operator's Guide Learning to Fly

To determine which blade is flying higher, stick 1/4" (6mm) wide pieces of highly visible tape (tracking tape) onto each blade. Locate the tape near the tip of one blade, and about an inch (25mm) from the tip of the other blade. Don’t worry about causing an imbalance; you will remove the tape when the blades are tracked.

Start the engine as outlined in the Preferred Engine Starting Procedure section of this Operator’s Guide. Once the engine is running properly, open the throttle until your Model 110 helicopter is just about to lift off (or to about half throttle ifyour Model 110 is weighed down). Look at the tips of the rotating rotor blades (but never place your eyes or face in-line with the blades). If you see two blade images as shown in the bottom of Fig. 2-4, then the blades are out of track (one blade is flying higher than the other).

Note: Before starting the engine, make sure that all radio and starting equipment batteries

are completely charged as per the manufacturer’s instructions. It is especially important that the transmitter and receiver batteries are charged. If the radio batteries die while you are flying, you will lose control and crash.

As the main rotor spins, look at the trackingtape and note which blade is flying higher. Adjust the length of the two mixing-arm/swashplate pushrods to increase the pitch of the low blade and decrease the pitch of the high blade. Remember that if you decrease the length of one of the pushrods, you must increase the length of the opposite one by the same amount to keep the linkages from binding. When the blades track properly, remove the tracking tape.

Dynamic Balancing

If the main rotor blades are tracking properly, but the helicopter still vibrates noticeably, it may be that the main rotor is not properly balanced. Luckily, it is possible to dynamically balance the main rotor at the field without removing it from the helicopter. To do so, stick a small piece of blade balancing tape to one of the main rotor blades and run the main rotor at flight speed.If the vibration level decreases, the extra weight of the trim tape is helping to balance the main rotor. If the vibration increases then remove the tape, stick it to the opposite blade and spin the main rotor again. Try different sizes of trim tape until you find one that minimizes the vibration. Repeat this procedure for the Arlton Subrotor stabilizer.

Neutral Stability

Helicopters are fascinating in their ability to hover and fly in any direction. By their nature, however, they are not positively stable. At best, they are neutrally stable.The concepts of positive stability and neutral stability can be illustrated by placing a marble in a cereal bowl and another on a table top.

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Operator's Guide Learning to Fly

If you nudge the marble in the bowl with your finger, it will roll back and forth and finally come to rest where it started in the center of the bowl. This is positive stability; the marble always ends up where it started. If,on the other hand, you push the marble on the table, it will continue to roll until you stop it. It will then sit still until you push it again. This is neutral stability; the marble stays put until pushed, and keeps moving until stopped.

Helicopters are somewhat like the marble on the table. When correctly trimmed they tend to remain in one spot until moved, and tend to keep movinguntil stopped. Unlike the marble example, however, helicopters vibrate and fly in air that is always swirling and rolling. As a result they do not stay in one place for very long, and require constant small control inputs to hover over a spot on the ground. The marble on the table would act more like a helicopter if a friend of yours shook the table and tilted it back and forth. You would have to constantly push the marble from different directions to keep it in one spot.

Big, heavy things (like luxury cars, or larger helicopters) tend to move more slowly and smoothly than small, light things. This is called the “Cadillac” effect (a Cadillac being a big, luxury car). As a small, light helicopter, the Model 110 responds to air disturbances more quickly than larger helicopters, and so bounces around more in the wind. The Model 110 is more like a compact car than a luxury car.

Stability, Control Power and Climb Performance

The flight stability and control power of the Model 110 are affected by the rotational speed of the main rotor. At high rotor speeds, the main rotor blades generate high gyroscopic forces that stabilize the main rotor, and minimize the effects of disturbances such as wind gusts. The rotor blades can also generate the high aerodynamic (air) forces needed to forcefully push the Model 110 around when the pilot moves the controls. On fixed-pitch helicopters such as the Model 110, the pitch of the main rotor blades determines the operating speed of the main rotor, and so directly affects stability, control power, and climb performance.

High blade pitch generally improves climb performance, but reduces stability and control power in hover. This is because rotor blades operating at a high pitch angle produce high lift at a relatively low rotor speed. At the low rotor speeds needed to hover, the rotor blades do not generate the gyroscopic forces needed for solid stability, or the aerodynamic forces need for snappy control. Low blade pitch, on the other hand, increases rotor speed and stability, but reduces climb performance.

The main rotor system on the Model 110 is designed to generate high lift with very little engine power. High lift is required to fly on hot daysand at high elevations where air density is low. When flying at low elevations (especially near sea level where air density is high) and with high blade pitch, the Model 110 may leave the ground without adequate rotor speed for acceptable stability and control power.

The usual solution to this problem involves reducing blade pitch or adding weight to increase rotor speed. Generally, main rotor blade pitch should be set to the highest value that provides acceptable stability (usually five degrees when flying near sea level, and six degrees at higher elevations). If, after adjusting the blade pitch, you

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Operator's Guide Learning to Fly

would like even more control power, try moving the Z-links in the rotor head to the alternate (inner-most) holes on the pitch plate and mixing arms. This will reduce the stabilizing input of the Arlton Subrotor stabilizer and increase the control input of the swashplate to the main rotors (thereby decreasing stability and increasing control power).

Adding weight to your Model 110 will significantly improve its flying qualities especially in windy conditions. Although it may seem odd to purposefully add weight to a flying machine, the additional weight (one to five ounces or 28g to 142g at sea level) requires a high rotor speed to lift off the ground. This high rotor speed generates the stability and control power needed to fly in gusting winds.

Adjusting Main Rotor Blade Pitch

The rotor blades on the Model 110 are semi-flexible and naturally vary slightly from blade to blade. Blade pitch is adjusted by interchanging the blade grips that hold the blades to the rotor head. Blade grips are available in even numbered two-degree increments (such as four-grips and six-grips). Odd-numbered grips are not available.

The Model 110 generally climbs best with a six-grip on each blade.Six grips increase natural blade pitch by six degrees, and are identified by six raised dots on the top of the grips. The Model 110 is generally more stable and controllable with the blades pitched to five degrees.

To change blade pitch from six degrees to five degrees, remove ONE six-grip and install a four-grip (four raised dots). After adjusting the mixing-arm/swashplate pushrods so that the blades have equal pitch (that is, after re-tracking the blades), each blade will be pitched five degrees. Note that re-tracking the blades usually requires two complete turns of the pushrod ball-links for a one degree change in blade pitch.

WARNING: Be careful not to reduce blade pitch somuch that the main rotor exceeds its maximum

rated speed since excessive speed could damage the mainrotor or the engine. When flying at low elevations (near sea level), or when using low blade pitch (such as two four-grips), use a fuel with a low (15%) nitromethane content to reduce the maximum speed of the engine.

Learning to Hover

Fly your Model 110 helicopter only in open areas outdoors away from people and property such as buildings and cars. The best flying sites when learning to hover are clean, smooth andhard such asasphalt or concrete. Whilenot as softas grass, these surfaces allow the model to skid around just a few inches off the ground. A drawback of asphalt or concrete is the abundance of abrasive grit kicked up by the rotor wash

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Operator's Guide Learning to Fly

that can be ingested by the engine (you could try sweeping an area clean with a broom). After mastering the basics of hovering flight, take off from concrete and fly over long grass. Long grass is much more forgiving than concrete for the occasional unintended landing.

Learn to fly on days with little or no wind. If there is a slight breeze, point the nose into the wind as shown in Fig. 2-5. The Model 110 will “weather vane”, actually making it easier to fly. Keep the nose pointed away from you at all times. When the nose is pointing toward you, three of the four controls (fore/aft cyclic, left/right cyclic and tail rotor) are reversed. Nose-in hovering is difficult for beginners, and is typically not attempted without considerable flying experience.

Breeze

Wrong

Right

15 ft. (5m) minimum

Figure 2-5.

Do not fly higher than three feet (1 m) at first, and fly far enough away to prevent hitting yourself if you become confused or something goes wrong. NEVER FLY CLOSER THAN 15 FEET (5m) TO YOURSELF OR ANYTHING ELSE! If you become disoriented, pull back on the left stick (throttle) to slow the engine down, and let your Model 110 settle to the ground. Resist all temptations to “punch” the throttle to full power and climb higher than three feet (you won’t know how to get down).

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Operator's Guide Learning to Fly

As you practice hovering, do not become discouraged if you are not immediately successful. Hovering is one of the most difficult piloting skills to learn, and NOBODY learns to fly a model helicopter without crashing several times. Most people require several hours of practice before they can consistently hover over a spot. Flying a model helicopter is very challenging, and as a consequence, quite rewarding when you finally get the hang of it.

Hint: Spectators never really know what you are trying to do when you are flying your

helicopter even when you miss your intended landing spot by fifty feet (15 m). If you wish to impress people, never tell them what you are trying to do, and they will assume you have everything under control.

Learning the Left Stick

The following describes a step-by-step process for learning to fly your Model 110 helicopter. The process begins with short hops using just the left control stick on the transmitter. After mastering the left stick, the right stick is added.

Hint: Are the transmitter control sticks comfortable for your fingers? Stick length and

centering tension are adjustable on most transmitters.

Place your Model 110 on the ground with the nose pointing into the wind, and the engine adjusted and idling. Stand about 15 ft (5m) behind the model, and slightly to the left or right (review Fig. 2-5 if necessary). Slowly open the throttle (move the left stick forward) to increase engine speed until the model is light on the skids, but not actually flying.

Move all controls to see if they work properly. Moving the left stick (tail rotor control) to the left and right should cause the nose to turn slightly. Moving the right stick (cyclic control) should cause the main rotor to tilt as previously described.

Concentrating on the left stick, slowly open the throttle until your Model 110 rises into the air. Pull the left stick back gradually to slow the engine and return to the ground. Repeat this step until accustomed to the throttle control.

While practicing thesehops, notice that the nose tends to turn to theleft or the right as the model lifts into the air. Try moving the left stick in the opposite direction to compensate. Remember to concentrate on the NOSE when using the left stick to turn, do not look at the tail rotor. If the nose rotates to the left, push the stick to the right, and vice-versa. The objective is to keep the nose pointed away from you. Learning the right stick later will be nearly impossible if the nose turns around toward you.

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Operator's Guide Learning to Fly

If the noseturns in thesame direction onevery hop, adjustthe trim leverunder the left stick to neutralize the turning tendency. You can also adjust thelength of the tail rotor pushrod by screwing the clevis in or out a few turns (if the nose turns left, shorten the pushrod; if right, lengthen it). In either case you are slightly changing the pitch of the tail rotor blades slightly to neutralize the turn.

While learning the left stick, it is helpful to have an experienced flier control the right stick (this requires a skilled pilot, since beginners often allow the model to turn nose-in). Agree ahead of time who-does-what in case things get out of control. If your helper on the right stick becomes disoriented, your helper should tell you immediately, in which case you should pull back on the throttle and land as quicklyas possible.

Adjusting the Arlton GyroÔ Stabilizer

The dual-gain Arlton Gyro stabilizer on your Model 110 greatly reduces tail swinging caused by wind gusts or changes in engine speed. If the tail on your Model 110 helicopter swings excessively with throttle changes, check that all parts of the gyro, tail rotor blades and spider slider linkages are oiled and move very smoothly. Any friction or binding will reduce gyro effectiveness. Also make sure that your gyro is set to maximum gain (use upper pin location on spider slider/gyro spindle).

Excessive tail swinging may also mean that your main rotor system (and consequently the tail rotor) is rotating too slowly. Even though the Arlton Gyro stabilizer is quite sensitive, at low speeds the tail rotor cannot produce enough thrust to keep the tail from swinging. Generally, adding weight to your Model 110 will increase main rotor speed and tail rotor effectiveness. For more information on increasing rotor speed, refer to the Stability, Control Power and Climb Performance section of this Operator’s Guide. In addition, adding weight (like small metal collars) to your gyro paddles can increase gyro effectiveness at low speeds.

The counterweight bolts on the Model 110 tail rotor blades balance the blades in flight, and influence the operation of the Arlton Gyro stabilizer. If the gyro is more effective in one turn direction than in the other, or if the gyro paddles are tilted during hover, the tail rotor blades may not be properly counter-balanced. Replace the 4-40 x 1/4" bolts with 4-40 x 3/8" bolts or 4-40 x 1/8" setscrews until the gyro rotor spins in a vertical plane when viewed from behind.

Tail Swing and Revo Mix

The tail rotor of the Model 110 is connected by gears directly to the main rotor. As a result, the main rotor and tail rotor change speed at the same rate. This means that changes in engine torque are roughly compensated for by changes in the thrust of the tail rotor. As long as throttle changes are made slowly and smoothly, the Model 110 will tend to climb and descend without much tail swing.

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Operator's Guide Learning to Fly

The main rotor and tail rotor, however, cannot change speed instantaneously. If you suddenly increase or decrease the throttle setting, the sudden change in engine torque will cause the tail to swing. The Arlton Gyro stabilizer will reducethis tail swing considerably, but not completely.

Radio transmitters designed especially for model helicopters usually have a function called “Revo Mix” which electronically mixes the throttle control with the tail rotor control, and automaticallyadjusts tail rotor blade pitch each time the throttle settingis changed. Radio transmitters designed for model airplanes do not have this function. An easy way to simulate Revo Mix on an airplane radio is to manually move the throttle (left) stick up and to the left or down and to the right when making rapid throttle changes. Each day before you go flying, look at the throttle stick and repeat to yourself “up and to the left”, “down and to the right”, “up and to the left”, “down and to the right” and you will be able to climb and descend without significant tail swing.

Learning the Right Stick

If no one is available to help with the right stick while you concentrate on the left stick, then allow your Model 110 to wander a few feet during each hop. If it drifts or tilts in a particular direction on every hop, adjust the appropriate trim levers next to the right stick in the opposite direction. For example, if it always tilts to the right, move the trim lever below the right stick to the left. You can also adjust the length of the servo pushrods controlling theswashplate. In either case, tiltthe swashplate OPPOSITE to the direction of drift. Note that it is impossible to trim any helicopter to sit still in the air. All helicopters require constant control inputs from the pilot to maintain a stationary hover.

After mastering altitude and heading control with the left stick, try using the right stick to hover over a spot. It will be difficult at first, but try to keep the model within a small area. Concentrate on the TILT of the main rotor disk and not on the motion of the helicopter body. The tilt of the main rotor controls the motion of the body. If you concentrate on the motion of the body, your control inputs will always be slightly behind the tilt of the main rotor and you will not be able to hold a steady hover.

You will notice a slight time lag between right stick control inputs and the resulting motions of the model as illustrated by Fig. 2-6. Frame 1 shows a helicopter hovering with the controls neutralized. In Frame 2, a control input tilts the helicopter to the left producing a small sideward thrust. Note that the helicopter tilts immediately with the control. In Frame 3, the controls are neutralized and the helicopter starts moving sideways. In Frame 4, with the controls still neutralized, the helicopter is moving rapidly.

It takes time to accelerate the Model 110 after the main rotor tilts. Move the right stick in the desired direction just long enough to tilt the main rotor, then bring the stick back to neutral. Be patient, and allow the model to accelerate slowly. If you hold the stick too long, the model will tilt too far, accelerate very quickly and possibly get away from you.

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Operator's Guide Learning to Fly

Figure 2-6.

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Operator's Guide Learning to Fly

Figure 2-7.

2-14 LITE MACHINES

Operator's Guide Learning to Fly

The same technique used to start a helicopter moving is used to stop the helicopter. In Frame 1 of Fig. 2-7, a helicopter is moving sideways with controls neutralized. In Frame 2, a control input immediately tilts the helicopter to the right creating a small sideways thrust. Frame 3 shows the controls neutralized, and the helicopter slowing to a stop. In Frame 4, the helicopter has stopped, and a control input tilts it back to level and into a steady hover.

The trick to the right stick is patience; usesmall control inputs and concentrate on the TILT of the main rotor. Once again, it may be helpful to have an experienced flier control the left stick while you learn the right. Once you have perfected your hovering technique, place markers on the ground and hover from one to another.

Translational Lift

When a helicopter is hovering in still air, the air flowing down through the main rotor (the “down-wash”) tends to circle around to the top of the rotor and flow through again. As the helicopter starts moving forward it moves into cleaner, undisturbed air. The main rotor is more efficient in the undisturbed air, and produces more lift for the same amount of engine power. The increased lift causes the helicopter to climb.

This effect is called “translational lift” because the extra lift is generated as the helicopter translates (moves forward) through the air. Translational lift affects both model and full-size (man carrying) helicopters. Some early, underpowered full-size helicopters could not climb above about twenty feet without moving forward to gain translational lift.

Gusts of wind also generate translational lift. Even when a helicopter appears to be hovering in one spot, wind gusts can blow away the rotor down wash and generate translational lift. The increased lift will cause the helicopter to climb. When the wind stops, the helicopter will suddenly fall. Piloting a helicopter in windy conditions can be difficult, and requires continuous throttle control inputs as the wind speed changes.

Tail rotors are also affected by translational lift. Forward motion and wind gusts will cause the tail rotor to generate more lift and turn the helicopter. Windy conditions therefore require both throttle and tail rotor control inputs in order to maintain a constant altitude and heading.

Translational lift is much easier to control when the main rotor and tail rotor are turning at high speed, and the speed of the down-wash is much greater than the speed of the oncoming wind. To increase rotor speed, refer to the Stability, Control Power and Climb Performance section of this Operator’s Guide.

LITE MACHINES 2-15

Operator's Guide Learning to Fly

Circles

Flying circles is a good way to prepare for forward flight. First practice hovering with the model turned sideways. It might help to turn your whole body with the model as shown in Fig. 2-8. Next, try flying circles around yourself as shown in Fig. 2-9. Practice both left and right circles. Concentrate on maintaining constant altitude (about 4ft or 1.2m) and distance (at least 15ft or 5m) at first. As you gain experience, fly larger circles at higher altitudes (do this in a big, open field away from people and obstructions).

Turn body with helicopter

Figure 2-8.

Circles teach you how to control altitude and heading with the left stick, and speed and position with the right stick. Notice that speed and altitude are related. As the model picks up speed, it gains altitude (due to translational lift). Note too that the tail rotor produces translational lift, so you will have to hold right tail rotor control when the model starts moving forward. You will also discover that forward cyclic control is required to maintain forward speed (in this regard flying a helicopter in forward flight differs from flying an airplane).

Once you are comfortable flying circles around yourself to the left and right, try reversing direction at the end of each circle (turn away from yourself to avoid flying nose-in). Circle in one direction at an altitude of 10 to 20 feet (3m to 6m), then turn away and fly the reverse circle.

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Operator's Guide Learning to Fly

Figure 2-9.

Figure 8’s

Having conquered hovering and circles, you have most of the basic flight skills needed for forward flight. The final skill to master is flying nose-in. When the nose of the model is pointing toward you, the left/right and fore/aft controls appear to operate backwards. Your radio is still operating properly - your frame of reference is simply reversed from that of the model.

To improve your nose-in flight skills, try flying figure 8’s in forward flight with half of the figure centered around you. Start by flying a circle around yourself (to the left, for example). At some point, reverse the direction of the circle by turning away from yourself (to the right). Continue turning (to the right) until the model returns to the point where you reversed the circle, then smoothly continue the initial circle (to the left).

As the model returns to the initial circle you will be flying nose-in for a few seconds. This is long enough to experience nose-in flight, but short enough to avoid becoming disoriented. Practice both left-hand and right-hand figure 8’s, and eventually stand outside the figure.

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Operator's Guide Learning to Fly

Descending from Altitude

If a helicopter descends straight down in still air, it will likely fly into its own down-wash. This is like flying into a strong downdraft and the helicopter will drop rapidly even at full power. The technical term for this situation is “descending vortex-ring state”. Pilots of full-size helicopters refer to it as “settling with power” (although it is a very psychologically unsettling condition). If you are ever caught in this situation, immediately fly forward or sideways to exit the down-wash.

When descending from altitude, keep moving forward (preferably into the wind). You will notice that substantial forward cyclic pressure is required to maintain speed in a descent. This is due to the decreased effectiveness of the cyclic controls as rotor speed is reduced (a characteristic of all fixed-pitch rotor systems). Another way to avoid settling with power is to fly in circles during descents. It is easier to judge forward speed when viewing the model from the side while it is circling rather than from the front when it is coming straight at you.

Landings

Landings can be a source of tail boom strikes for beginning helicopter pilots. Airplane fliers usually pull back on the elevator stick on the transmitter when flaring their airplanes for a landing. Helicopter fliers with experience flying airplanes sometimes unconsciously pull back on the fore-aft cyclic stick as their helicopter nears the ground. This tilts the helicopter backward. When the helicopter lands, the fuselage rotates forward parallel to the ground, but the main rotor blades continue their downward and backward motion and eventually strike the tail boom. To avoid this problem, apply a little forward cyclic as your helicopter touches the ground. Forward cyclic also tends to keep the tail rotor high when landing in tall grass.

When you suddenly drop the throttle after landing, the Model 110 will tend to rotate to the left. By suddenly lowering the throttle you have removed the engine torque driving the main rotor, but the main rotor and tail rotor are still turning at high speed. The thrust forceproduced by the tail rotor pushes the nose of thehelicopter to theleft. To make your landings more precise, reduce the throttle slowly after touch-down, or apply right tail rotor control when reducing throttle. For more information on tail swing, refer to the Tail Swing and Revo Mix section of this Operator’s Guide.

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Operator's Guide Engine Operation

ngine Operation

The Lite Machines Model 110 helicopter is powered by the Norvel Vmax-6 helicopter engine. The Vmax-6 is a high-performance glow-fuel engine developed specifically for the Model 110 from the Norvel AME series of award winning racing engines. The rugged Vmax-6 crankshaftis supported by adurable bronze bushing to withstandthe side-loads generated by the gear driven rotor system of the Model 110. The Vmax-6 carburetor and five directional transfer ports are tuned for easier starting and extra lugging power. The unique Vmax-6 throttle/muffler provides precise throttle control, and traps exhaust gasses inside the cylinder to keep the glow plug hot for a lower, more reliable idle.

Fuel Mixture and Compression

The two most important factors affecting the performance of your Norvel Vmax-6 are fuel/air mixture and compression. In operation, air and fuel enter a model piston engine through the carburetor and flow into the cylinder above the piston. As the piston moves up within the cylinder, it compresses the fuel/air mixture against the glow plug at the top of the cylinder. At a certain point the fuel/air mixture ignites, pushing the piston down and producing useful power. The needle valve on the carburetor meters the amount of fuel mixed with the air. Too much fuel (too “rich”) causes the engine to slow down and lose power. Too little fuel (too “lean”) causes the engine to over-heat, slow down and lose power. The Vmax-6 will operate best within a needle valve range of about 1/4th turn.

Proper compression is needed for a reliable idle as well as maximum power. Compression is adjusted on the Vmax-6 by inserting or removing thin copper washers under the glow plug. If compression is too high, the fuel/air mixture ignites too soon. This does not affect top-end power appreciably, but the engine may stop abruptly while idling. This is bad news since the engine must idle well in order for the Model 110 to descend from altitude. If compression is too low, the engine may not produce enough power for normal maneuvering.

Compression is affected by air density. Anything that increases or decreases air density increases or decreases compression. The elevation of your flying site and the local temperature both affect air density, and so have a major influence on compression.

As elevation and air temperature increase, air density decreases. To maintain the same piston compression at high elevations and air temperatures, the volume in the cylinder above the piston must be reduced slightly by removing washers. This means that if you fly at a high elevation (5000 ft. or 1524m. at Denver, Colorado, USA, for instance), you will use fewer washers under the glow plug than at a lower elevation (700 ft. or 213m. at Lafayette, Indiana, USA). It also means that if you last flew when

LITE MACHINES 3-1

Operator's Guide Engine Operation

the air temperature was 75°F (24°C), you may need to add additional washers before flying with the air at 40°F (4°C). The large temperature drop will otherwise affect engine idle because the colder, denser air increases compression.

When air density decreases, less fuel and air enter the engine on each piston stroke. This means that the engine will not produce as much power at high elevations or temperatures where the air is thin. Lift produced by the main rotors also depends upon air density in a similar way. The performance of all aircraft (including full size helicopters) degrades considerably at high elevations and/or hot days.

Hint: Vmax-6 engines operating on a warm day at 500 ft (300m) above sea level on 15%

nitro fuel generally need two washers for proper compression. Add an additional washer for each 5% of nitro above 15%. For example, use four washers with 25% nitro fuel.

Breaking-In a New Engine

Before starting your new Norvel Vmax-6 remember that all piston engines have a break-in period (twenty minutes to over an hour) in which they do not produce peak power. The piston and cylinder of the Vmax-6 are selectively matched at the factory to fit tightly at top-dead-center (where the piston is at the top of the cylinder). During break-in, the piston and cylinder wear together to form a perfect fit that will last the life of the engine.

To break-in yournew Vmax-6, runit rich (whereit runs slowly and unevenly) for two to three minutes before leaning it out. Then alternately run lean (where it just starts to speed up and run steadily) for two minutes and then rich for two minutes for a total of about 20 minutes or two tanks of fuel. This lean-rich break-in procedure not only wears the surfaces of the piston and cylinder, but also heats and cools the engine which relieves built-in stresses in the metal of the piston and cylinder.

You may break-in your new Vmax-6 on an engine test stand or in your Model 110. Always use a Lite Machines heat sink on the Vmax-6 in your Model 110 helicopter. If you use an airplane style glow head without the heat sink, your engine will immediately overheat and seize. NEVER run your Vmax-6 on an engine test stand without an airplane propeller. The propeller not only cools the engine, but produces drag which keeps the engine from over-speeding. If you run the Vmax-6 on a stand with only the clutch from your Model 110 (with no propeller), the engine and clutch can be damaged when the engine over-speeds, and THE CLUTCH SHOES CAN BE THROWN OFF AT HIGH SPEED AND POSE A SERIOUS HAZARD.

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Operator's Guide Engine Operation

General Operating Considerations

Over time, you will learn to gauge the condition of your engine by the sound it produces. For instance, a high pitched, even tone usually means the engine is running well. A slightly lower tone, with an uneven warble may indicate that the engine is too hot or is overloaded. If you have engine problems, refer to the Engine Trouble-Shooting section of this Operator’s Guide.

Remember that operating conditions can affect engine life. Helicoptersoperate close to the ground, and kick up dust and sand that can scratch the inside of the cylinder and damage the engine. Avoid flying over loose dirt, and use a fuel filter to remove dirt from the fuel. Particles in the fuel may clog the carburetor making the engine impossible to start or adjust. This problem can be very difficult to diagnose.

If you area beginner, you can cutyour learning time in halfif you locate someone who knows about model engines and/or helicopters. Local hobby shopsusually have a list of model airplane/helicopter clubs in your area. Whether you fly a helicopter or an airplane, you should not fly alone. MAKE SURE SOMEONE IS ALWAYS NEARBY

TO HELP YOU IF YOU NEED ASSISTANCE OR HURT YOURSELF. ADULT SUPERVISION IS STRONGLY RECOMMENDED FOR MINORS.

Engine Starting Summary

This section summarizes proper engine starting procedures. For more detailed information, refer to the Preferred Engine Starting Procedure section of this Operator’s Guide.

1. Turn on radio transmitter and receiver power.

2. Fill fuel tank with fuel.

3. Open needle valve 2-1/2 turns.

4. Connect glow plug battery to glow plug.

5. Start turning engine with electric starter.

6. Hold finger over carburetor intake for one second to prime engine (keep turning engine with electric starter).

7. Remove electric starter from engine to see if engine is running.

8. Repeat step 6 and 7 as required.

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Operator's Guide Engine Operation

Preferred Engine Starting Procedure

This section is a detailed, step-by-step procedure for starting the Norvel Vmax-6 in your Model 110 helicopter. Since you will probably want to try flying your Model 110 once the engine is running, you should read the Learning to Fly section of this Operator’s Manual to understand the various flight controls. Starting the engine with a helper isstrongly recommended. Priming and adjustingthe engine are mucheasier with the aid of a friend.

1. Make sure you bring all of the necessary equipment with you to the flying field including hand tools like pliers and wrenches, electric starter and battery and a supply of paper towels and spray cleaner.

2. Put on your eye and hearing protectors. ALWAYS WEAR EYE AND HEARING

PROTECTION, SUCH AS HIGH-IMPACT SAFETY GLASSES AND EAR-PLUGS, WHEN OPERATING YOUR ENGINE. ANYONE HELPING YOU SHOULD WEAR EYE AND HEARING PROTECTION AS WELL. Eyewear not

only helps protect your eyes from the spinning rotors, but also from oil droplets thrown outward by the spinning engine and clutch.

3. Fill the fuel tank to within 1/4" of the top with model engine fuel containing 15% nitromethane and castor oil or a castor/synthetic oil blend. Some fuels contain only synthetic oils whichcan break down at high temperatures andlead to engine damage. Use a fuel containing an oil mix that is about 50% castor oil to avoid engine damage.

Warning! Never add fuel to your Model 110 while the glow-plug battery is connected to the

engine. Sparks from the electrical connection can start a fuel fire.

4. Make sure yourradio frequency is clear. TWO RADIOS CANNOT OPERATE ON

THE SAME FREQUENCY (CHANNEL) AT THE SAME TIME. IF YOU TURN ON YOUR TRANSMITTER, AND IT IS ON THE SAME FREQUENCY (CHANNEL) AS THE TRANSMITTER OF SOMEONE WHO IS ALREADY FLYING, THE FLYING AIRCRAFT WILL LOSE CONTROL AND CRASH.

5. After you are sure that your frequency is clear, turn on the radio (transmitter first) and check the operationof all controls. If this is the first flight ofthe day, perform a radio range check. With the transmitter antenna fully collapsed,slowly walk away from the model while moving one of the controls. You should get at least 50 feet away before losing signal (this distance varies with different radio equipment). Do not start your engine or fly if the radio fails the range check. NEVER RANGE

CHECK WITH THE ENGINE RUNNING! THE ENGINE MAY GO TO FULL POWER AS YOU EXCEED THE OPERATING RANGE OF THE RADIO.

6. Fully extend the transmitter antenna before starting the engine.

7. If starting the engine for the first time, carefully turn the needle valve clockwise with a small screwdriver until fully closed (do not force it), then open it counter-clockwise 2 to 2-1/2 turns.

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Operator's Guide Engine Operation

8. Connect your electric starter to a 12 volt starter battery. You may need to reverse

the rubber insert in the starter bell to fit the engine starter cone. The starter should spin in the direction shown in Fig. 3-1. If not, reverse the starter wires on the battery.

To power panel

Note starter

Glow plug clip

rotation:

Carburator inlet

Apply pressure in this direction

Starter

12 volts

Figure 3-1.

9. Connect the glow plug to a 1.2 volt battery or to a hobby power panel.

Note: Lite Machines SpiraLite Speed and Norvel Freedom XL glow plugs require 1.2

volts. The best way to power a Lite Machines or Norvel glow plug is with a DuBro Kwik-Start clip. Never wire the glow plug directly to 12 volts (like your car battery) because the plug will burn out.

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Operator's Guide Engine Operation

10. Connect the glow plug clip to the glow plug on theengine as shown inFig. 3-1 and Fig. 3-2. The meter on the power panel (not shown) should indicate a good electrical connection.

Preferred starting method:

Glow plug battery

11. MAKE SURE YOU ARE WEARING EYE AND HEARING PROTECTION. Model engines throw out oil droplets when running. It is nearly impossible to avoid getting oil on you and your clothing while starting and tuning the engine.

12. Move the transmitter throttle stick (left stick) to about 1/3 throttle, and the throttle trim lever to full. Hold the rotor head with one hand, and tilt your Model 110 on its side WITH THE RIGHT SKID ON THE GROUND as shown in Fig. 3-1 and Fig. 3-2.

13. Spin the engine with the electric starter (the engine should rotate counter-clockwise when viewed from below). Push firmly, but not excessively on the starter cone at the angle shown in Fig. 3-1. Do not push hard straight against the end of the starter cone; the engine is not designed for high end-loads.

3-6 LITE MACHINES

Figure 3-2.

Operator's Guide Engine Operation

14. The fuel line from the tank must be full of fuel before the engine will start. While

you spin the engine with the starter, ask your helper to hold a finger over the carburetor inlet for one or two seconds. This will draw fuel from the tank into the engine. You may have to repeat this procedure several times before the engine will fire. If you do not have a helper, disconnect the glow plug, place your finger over the carburetor inlet, and turn the engine by hand until fuel fills the fuel line. If your engine is new it may not turn easily against compression. It will turn more easily after running for about 30 minutes.

15. If the starter slips on the starter cone, the piston may be hydraulically locked. Do

not force it to turn or you could damage the engine. Remove the heat sink and glow plug and spin the engine with the electric starter for one second to clean the excess fuel from the cylinder and crankcase. Replace the glow plug and heat sink, and clean the oil off of the starter cone and the rubber insert on the starter motor with a paper towel.

16. If theengine refuses to pop, remove the heat sink and glowplug, and connect the

glow plug to the glow plug clip (be careful, it gets very hot). The entire coil should glow bright orange (not visible in direct sunlight). If it does not, the glow plug or glow plug clip may be bad, or the glow plug battery may need charging.

Hint: All glow plugs have a limited useful life. When you suspect a glow plug is going

bad, replace it with a new one.If engine performance improves, the old glow plug was bad.

17. When the engine starts, immediately lower the throttleso that the clutch shoes do

not wear against the clutch bell. Be careful, if the throttle is set too high the clutch will engage and try to rotate the whole fuselage (and tail rotor) toward you.

18. Remove the glow plug clip, and place your Model 110 on its skids on the ground

so that the main rotor can rotate freely.

19. If your Vmax-6 engine is brand new, run it rich for at least two tanks of fuel toallow

the piston and cylinder to wear together before leaning the mixture for maximum power.

Alternate Starting Method

Fig. 3-3 illustrates an alternate starting method requiring two people: one to hold and start the Model 110 and another to hold and operate the transmitter. This starting method is illustrated for completeness and because the engine sometimes starts more easily when held vertically. This method is not preferred because of the proximity of the rotating rotor blades to the person starting the Model 110.

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Operator's Guide Engine Operation

BE CAREFUL - AVOID SPINNING ROTORS!

Glow plug clip

Apply pressure in this direction

Starter rotation:

Starter

12V

Figure 3-3.

Hold the Model 110 by the canopy and front landing gear struts as shown WITH THE MAIN ROTOR ABOVE AND TILTED AWAY FROM YOU. Once the engine is

running, lower the throttle and place the Model 110 on the ground.

Before starting the engine, make sure your helper knows how to operate the controls on the transmitter, and NEVER moves the cyclic controls (right stick) while the rotors are turning. THE CYCLIC CONTROLS ARE VERY POWERFUL, AND THE MODEL

110 COULD ROTATE OUT OF YOUR GRASP AND STRIKE YOUR HANDS, ARMS OR FACE. Even though the Model 110 is relatively small, the RAPIDLY ROTATING ROTOR BLADES CAN CAUSE SERIOUS INJURY. For this reason, this starting

method is NOT recommended.

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Operator's Guide Engine Operation

Warning! NEVER ATTEMPT THE ALTERNATE STARTING METHOD WITH A LARGER

HELICOPTER! THE ROTATING ROTOR BLADES ON A LARGE HELICOPTER CAN BE LETHAL!

Adjusting Fuel Mixture and Compression

This section outlines a step-by-step procedure for adjusting fuel mixture and compression on the Norvel Vmax-6 engine in your Model 110 helicopter.

1. Set the model on the ground with the engine idling. Slide a heavy pole, wooden

plank, broom handle, etc., from side to side over the landing gear skids and between the wire struts in order to weigh the Model 110 to the ground. With the Model 110 safely grounded, you can adjust the needle valve at full power. Slowly open the throttle. If the Model 110 lifts into the air, place a heavier weight across the skids.

2. Move the throttle stick and throttle trim lever on the transmitter to full throttle.

3. Carefully reach under the rotor blades and slowly open (screw out) the needle

valve with a small screwdriver until the engine runs roughly (four-strokes). This fuel/air mixture is too rich. MOVE SLOWLY AND CAREFULLY ANY TIME YOU

ARE WORKING NEAR THE ROTATING ROTOR BLADES! DO NOT TOUCH THE ROTATING ROTOR BLADES WITH YOUR HAND OR ARM! ALSO WATCH OUT FOR THE TAIL ROTOR BLADES!

4. Slowly close (screw in) the needle valve. The engine will run faster and

smoother, and the engine sound will increase in pitch. At some point you will hear it slow down again. This mixture setting is too lean. The optimum needle valve setting lies roughly half way between the rich and lean settings. It is best to operate with a slightly rich mixture since the engine will run cooler.

5. Open (screw out)the needle valve tothe optimum point halfway between therich

and lean settings.

6. Close the throttle (throttle trim is still high). The engine should idle smoothly, and

slowly enough that you can hold the main rotor without feeling much clutch drag. If the engine runs too fast, try reducing throttle trim slightly. If it stops suddenly, the compression may be too high - add another copper washer under the glow plug and adjust the needle valve. BE CAREFUL, THE HEAT SINK IS HOT!

Hint: Never hold the rotor head while tightening or loosening the heat sink, you could

bend the main shaft. Hold the crutch near the tail boom instead.

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Operator's Guide Engine Operation

7. Open the throttle to full, and listen to the engine sound closely. The engine should smoothly and rapidly increase speed to a maximum. If it sputters and increases speed slowly, or four-strokes (runs roughly) occasionally, it may be slightly rich, so screw IN the needle valve slightly. If it reaches top speed then sags or “warbles”, it may be lean, so screw OUT the needle valve slightly.

8. If the needle valve seems to be adjusted correctly, and the engine idles acceptably, but does not produce much power, it is possible that it is not yet broken-in or the compression is too low. Try removing a washer from under the glow plug and readjusting the needle valve. Be careful with the glow plug washers, they bend easily. Discard damaged washers.

9. After the needlevalve and compression are set, theyneed not be adjusted for the rest of the day unless the temperature (air density) changes. If it gets cooler, adjust the needle valve out (rich) slightly.

Inspecting SpiraLite Speed Glow Plugs

This section refers to the operation of SpiraLite Speed glow plugs, and not to Norvel Freedom XL glow plugs.

To start your Norvel Vmax-6 engine, the coil in your SpiraLite Speed glow plug must glow bright orange. To test a glow plug, connect it to a glow plug battery with a glow plug clip, and cup your hands around the plug to keep it out of direct sunlight. BE CAREFUL, THE PLUGWILL GET HOT QUICKLY. Theentire coil should glowbright orange. If no part of the coil glows bright orange then disconnect the glow plug clip and check your battery and wire connections.

If only a portion of the coil glows orange, then the coil may be touching itself and creating an electrical short circuit, or touching the glass insulation sealing the top of the plug and losing heat. In either case, disconnect the glow plug clip and CAREFULLY separate the loops of the coil from each other, and lift the coil slightly away from the glass insulation with the tip of a hobby knife as shown in Fig. 3-4. Test the glow plug again before installing it in your Model 110.

Glow Plug

3-10 LITE MACHINES

Hobby knife

Figure 3-4.

Operator's Guide Engine Operation

Fuel Contamination

All model glow-engines use a glow plug with a platinum metal coil. The platinum metal in the coil acts as a catalyst to ignite the air/fuel mixture in the engine. To operate properly, the air/fuel mixture must actually touch the surface of the platinum coil for the catalytic reaction to occur. If the surface ofthe coil is coated with anything, even if only a few atoms thick, the catalytic reaction cannot occur and the engine will stop running.

Certain brands of model engine fuel contain chemical additives (such as anti-rust compounds) that can foul the glow plug on the Norvel Vmax-6 engine. Some engines will run on these fuels for a flight or two, but then loose power. Some engines will not start at all. Do not use fuels with your Vmax-6 engine that contain chemical additives such as anti-rust compounds.

Many varieties of rubber will dissolve in glow fuel and quickly foul a glow plug coil. Avoid using rubber fuel bulbs, syringes with rubber plungers, and neoprene fuel tubing when transferring fuel into your Model 110. Use only silicone fuel tubing and plastic (polyethylene) containers to store or transfer fuel.

There is no practical way of cleaning a contaminated glow plug coil. Discard contaminated glow plugs when changing to a new fuel or after using rubber in the fuel system.

Hint: Use the Lite Machines Lil’ Squeezer™ fuel system to quickly fuel and de-fuel your

Model 110. The Lil’ Squeezer™ fuel system consists of a fuel storage bottle that

protects your fuel from sunlight during storage and a filtered transfertube that will not contaminate your fuel with rubber byproducts.

Synthetic Oils

Some brands of fuel contain synthetic oil that breaks down at relatively low temperatures. During a hot, lean run, synthetic oil may not provide sufficient lubrication to the Vmax-6 piston and cylinder, and the piston may seize inside the cylinder and damage the engine.

Do not use fuels containing only synthetic oil with your Vmax-6 engine. Use fuels containing castor oil or castor/synthetic oil blends. For instance, if you like Morgan’s brands fuels, do not use Morgan’s Cool Power fuel with synthetic oil (the green stuff). Instead use Morgan’s Omega fuel with castor/synthetic oil blend (the pink stuff).

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Operator's Guide Engine Operation

Electric Starter Effect on Glow Plug

The Norvel Vmax-6 usually starts easily. On-going difficulty with engine starting is sometimes a sign of a field-equipment problem. Many fliers have a field box with a small 5 Ah motorcycle battery connected to a hobby power panel which powers the glow plug and electric starter motor. Common electric starters are designed to start .40 and .60 sized engines, and therefore draw high current from the field box battery.

Even though a glow plug may appear to glow orange (hot) when connected to the field box battery by itself, it may cool substantially when the electric starter is operated. This means that the glow plug will stop working just as the starter motor begins to spin the engine, so the engine may not start. The plug will heat up again when the starter motor is turned off, making it appear as though the plug is working properly.

To check for this problem, plug a glow plug clip and a standard electric starter into a power panel. Connect the glow plug clip to a glow plug, and cup your hands around the plug to keep it out of direct sunlight. The coil should glow bright orange. BE

CAREFUL, THE PLUG WILL GET HOT QUICKLY.

Turn on the electric starter. If the field box battery is small, old, or low on charge, the plug coil will cool and stop glowing. Turn off the starter and the plug will again glow orange. Also try operating the starter in one second pulses. Notice that the glow plug remains hot longer if the starter is pulsed.

3-12 LITE MACHINES

Operator's Guide Engine Operation

Engine Trouble-Shooting

This section identifies a variety of problems that you may encounter when starting and operating the Norvel Vmax-6 engine in your Model 110 helicopter. Possible causes and suggested actions are also provided.

Engine will not pop:

Glow plug bad Remove glow plug and test. Try different glow

plug.

Glow plug clip bad Test clip on another glow plug.

Glow plug battery bad Recharge glow plug battery or replace if

necessary.

Electric starter draining glow plug battery

Glow plug voltage low Check glow plug battery or power panel for

Engine not primed (not enough fuel)

Engine flooded (too much fuel)

Bad/old fuel Buy new fuel, change brands (fuel must contain

Heat sink loose Tighten heat sink (protect your hand with cloth).

Compression too low Remove glow plug washers (leave at least one

Needle valve closed Open needle valve 2 to 2-1/2 turns.

No fuel in tank Add fuel (and consider a simpler hobby).

Recharge battery, use larger capacity battery, pulse starter at one-second intervals, use smaller starter, or use separate glow plug and starter batteries.

proper operation.

Hold finger over carburetor inlet and spin engine to pull fuel into carburetor.

Close needle valve and try starting engine to burn-off excess fuel. Open needle valve and try starting engine again.

castor oil).

If necessary, apply a very small amount of thread lock (temporary type) to heat sink threads.

washer in engine).

LITE MACHINES 3-13

Operator's Guide Engine Operation

Engine pops but will not start:

Compression too high Add glow plug washers.

Glow plug coil touching glow plug body

Glow plug bad Remove glow plug and test. Try different plug.

Fuel mixture too lean Open needle valve ½ turn.

Glow plug coil touching glow plug body

Carburetor clogged Remove needle valve and fuel line. Back-flush

Bad/old fuel Buy new fuel, change brands (fuel must contain

Electric starter too slow Try smaller, faster starter. Check charge of

Pull coil lightly away from plug body with hobby knife (SpiraLite Speed plug only).

needle valve body with fuel. Reassemble needle valve and fuel line.

castor oil).

starter battery.

Electric starter holding back engine

Engine pops, fuel sizzles, fuel drips out of carburetor:

Engine flooded (too much fuel)

Engine runs rough (four strokes), sputters and dies:

Mixture too rich Close needle valve ½ turn.

Engine runs at high speed for a few seconds then stops:

Fuel line not filled with fuel

Needle valve not adjusted correctly

Carburetor clogged Remove needle valve and fuel line. Back-flush

Remove starter from engine when engine starts popping

Close needle valve and try starting engine to burn-off excess fuel. Open needle valve and try starting engine again. Some fuel dripping from carburetor is normal when fuel tank is full and the oil provides lubrication for the goop clutch.

Hold finger over carburetor inlet and spin engine to pull fuel into carburetor.

Close needle valve completely then open 2 to 2-1/2 turns.

needle valve body with fuel. Reassemble needle valve and fuel line.

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Operator's Guide Engine Operation

Engine runs at full power for 1-2 minutes then suddenly stops:

Mixture too lean Open needle valve 1/8 turn.

Cylinder head leak Oil bubbles around glow plug indicate a leak

under glow plug. Make sure glow plug seat is clean and washers are not bent.

Bad glow plug, glass seal leaking

Carburetor clogged Remove needle valve and fuel line. Back-flush

Engine not producing high power:

Fuel mixture too rich or too lean

Compression too low Remove glow plug washers (leave at least one

Compression too high, fuel pre-detonating

Bad/old fuel Buy new fuel, change brands (fuel must contain

Bad/old glow plug Replace glow plug (coil becomes coated over

Heat sink loose Tighten heat sink (protect your hand with cloth).

“Varnish” buildup on piston/cylinder (looks light brown)

New engine not completely broken-in

Crankcase back plate not tight

Not enough nitromethane in fuel

Replace glow plug (normal tests will not find this problem).

needle valve body with fuel. Reassemble needle valve and fuel line.

Adjust needle valve. Make sure to run engine for 20-30 seconds before adjusting needle valve so that engine is hot.

washer in engine).

Add glow plug washers.

castor oil). Do not use fuel containing rust inhibitors. Do not use dirty fuel containers.

time with combustion by-products which prevent good catalytic ignition of the fuel).

If necessary, apply a very small amount of thread lock (temporary type) to heat sink threads.

Remove varnish (a byproduct of over-heated castor oil) with 3M Scotchbright cloth or fine steel wool. Never use sandpaper!

Follow manufactures break-in instructions.

Remove engine and back plate, apply thread lock (temporary type) sparingly to back plate threads and reassemble.

Use fuel with more nitromethane (15% - 25% nitro recommended).

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Operator's Guide Engine Operation

Engine losing power over time:

Air temperature/humidity changing compression

Dirt particle scratched cylinder wall or crankshaft seal

“Varnish” buildup on piston/cylinder (looks light brown)

Crankcase back plate not tight

Old engine naturally wearing out

If air much cooler, add glow plug washer; if much warmer, remove washer.

Replace piston/cylinder or crankcase.

Remove varnish (a byproduct of over-heated castor oil) with 3M Scotchbright cloth or fine steel wool. Never use sandpaper!

Remove engine and back plate, apply thread lock (temporary type) sparingly to back plate threads and reassemble.

Replace engine.

Engine sound “warbles” (oscillates) at high throttle, overheats:

Main rotor blade pitch too high, engine overloaded

Compression too high, fuel pre-detonating

Bad ball bearing on main rotor or tail rotor

Gear mesh too tight/ too loose

Gyro dragging Relubricate gyro hub and gyro spindle.

Rotor head not balanced (everything shaking)

Rotor blades not tracking (everything shaking)

Main shaft bent (everything shaking)

Change one blade grip to lower blade pitch and re-track rotor blades.

Add glow plug washer(s).

Replace bearing (bad bearing may not be noticeable when turned by hand, or may feel slightly gritty).

Remesh gears. Make sure engine mounting bolts are tight.

Rebalance rotor head.

Track rotor blades.

Remove main rotor from main shaft. Attach paper clip wire or other pointer to fuselage keel and rotate shaft by pointer to determine direction of bend. Press firmly on top of shaft with thumb in direction opposite of bend. Repeat procedure until shaft is straight. Reassemble main rotor.

Engine sound oscillates at all throttle settings:

Clutch shaft loose, clutch shoes slipping against prop plate

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Tighten clutch shaft in end of engine crankshaft.

Operator's Guide Engine Operation

Engine suddenly stops at low throttle or while descending from altitude:

Compression too high, fuel pre-detonating

Bad glow plug, glass seal leaking

Carburetor clogged Remove needle valve and fuel line. Back-flush

Engine runs well for 20 to 30 seconds then sags:

Fuel mixture too lean, engine slowly overheating

Compression too high, fuel pre-detonating

Heat sink loose Tighten heat sink (protect your hand with cloth).

New engine not completely broken-in

Improper fuel, engine seizing

Add glow plug washers.

Replace glow plug (normal tests will not find this problem).

needle valve body with fuel. Reassemble needle valve and fuel line.

Open needle valve slightly.

Add glow plug washers.

If necessary, apply a very small amount of thread lock (temporary type) to heat sink threads.

Follow manufactures break-in instructions.

Use fuel containing castor oil or castor/synthetic oil blend. Some pure synthetic oils break down at high temperatures and can damage small engines.

Engine runs inconsistently:

Something is leaking Check needle valve, crankcase back plate and

Hole in fuel tubing Replace fuel tubing.

Engine running very fast, but Model 110 will not fly:

Rotor blade pitch too low Change blade grips to increase main rotor blade

Local altitude/ temperature/humidity too high

carburetor for leaks.

pitch.

Wait for air temperature/humidity to drop. If possible, fly at a lower elevation.

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Operator's Guide Engine Operation

Engine will not turn, electric starter slips on starter cone:

Excess fuel in cylinder causing hydraulic lock above piston

Starter cone covered with oil

Engine runs for many flights, but then runs poorly or does not start:

Carburetor clogged Remove needle valve and fuel line. Back-flush

Bad fuel fouling glow plug Buy new brand of fuel, change glow plug.

Do not force engine to turn with electric starter! Remove heat sink and glow plug, and spin engine for one second to clear out excess fuel. Replace plug and heat sink.

Clean engine starter cone and rubber insert on electric-starter motor with a paper towel.

needle valve body with fuel. Reassemble needle valve and fuel line.

Nothing will work, situation is hopeless:

Gremlins in system Call Lite Machines

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Operator's Guide Zen and the Art of Helicopter Maintenance

en and the Art of Helicopter Maintenance

Model helicopters, like their full-size counterparts, spend most of their time shaking themselves apart. The following sections provide a maintenance schedule and basic repair techniques for your Lite Machines Model 110 helicopter.

General Maintenance

Periodically check all parts of your Model 110 for breakage, fatigue cracks, loose screws and normal wear before flying each day and when cleaning up at home. After the first few flights check all nuts and bolts, especially those holding the engine to the crutch. The plywood compresses slightly after assembly and the engine bolts may loosen. Helicopters can also be rough on radio equipment, so check the servos occasionally for proper operation.

Keep your Model 110 as clean as reasonably possible, and keep the radio compartment and mechanics free of oil and debris. Oil collects dust and dirt that can cause problems in servo connections and the switch harness. Keep the rotor blades clean of sand and dirt for best performance.

Other than incorrect assembly, most ongoing problems with helicopters are directly traceable to poor maintenance. Not only does this lead to unnecessary frustration, but maintenance failures can constitute a serious safety hazard. Periodically review the following maintenance items and suggested maintenance intervals as part of your preventative maintenance program.

Engine Maintenance

•

Check heat sink tightness (every 5 flights, DO NOT HOLD THE ROTOR HEAD WHEN TIGHTENING THE HEAT SINK, you may bend the main shaft.)

•

Oil clutch bell bushing (every 5flights, one drop of oil on shaft inside clutchbell is suffi cient)

•

Check all mounting bolts (first after 15 minutes run time, then every 20 flights)

•

Check clutch bell pinion for wear (every 30 flights, sand and grit are hard on metal gears)

•

Visually inspect for loose engine backplate (every 50 flights)

•

Periodically back flush engine fuel filter (every 50 flights)

•

Check for varnish build-up in engine cylinder if necessary

•

Keep engine free of grit and debris

•

Keep heat sink fins clean and unobstructed

•

Keep carburetor screen clean and unobstructed

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Operator's Guide Zen and the Art of Helicopter Maintenance

Radio Maintenance

Transmitter

Watch power meterwhen flying (NiCad batterieslose capacity with age,and will grad

•

ually lose charge if unused for several days.) Wipe clean occasionally using soft paper toweland spray glass cleaner (when neces

•

sary) Observe battery charging instructions (do not overcharge)

•

Do not expose to extreme temperatures

•

Airborne System

Check for loose/missing servo mounting screws (every 30 flights)

•

Check servo travel (every 30 flights, servos should move smoothly throughout entire

•

range) Check servo speed (every 30 flights, servos should move quickly to maximum throw -

•

sluggish response may indicate low battery, binding linkages or bad electronic ampli fier)

Check wiring for cracks or chafing in the insulation (every 30 flights, especially where

•

rubbing on structure) Check plug connectionsfor loosening, andoil or dirtcontamination (every 30flights)

•

Keep all components free of oil

•

• Observe battery charging instructions (Do not over-charge. A 250 mAh pack should

be charged for half the time of a 500 mAh pack using the same charger.)

•

Check receiver battery charge after the first several flights each day (Special hand-held meters that simulate servo load are available at hobby shops. On-board monitoring systems are not recommended because of the added weight.)

Main Rotor Maintenance

•

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Check tightness of all bolts, setscrews and pins (every 10 flights) Check the main rotor hub and blades for cracks, chipped ends and any other damage.

(Do not fly damaged blades. Always replace blades in sets.) Check swashplate for wear, adjust if necessary (every 50 flights) Check all linkagesfor wear, binds(every 50 flights,replace ball linksif slop develops) Check ball bearings (every 100 flights, add oil if they move smoothly, replace bear

ings that feel “gritty” or drag when rotated) Check main rotor hub, and replace if hub bolt hole is enlarged or cracked (every 100

flights)

Operator's Guide Zen and the Art of Helicopter Maintenance

Tail Rotor and Arlton Gyro Maintenance

Check tightness of all bolts, setscrews and pins (every 10 flights)

•

Remove Arlton Gyro stabilizer and lubricate gyro spindle with oil every 2 hours (every

•

10 to 15 flights) Oil spider and spider slider (every 20 flights)

•

Oil push/pull rod (every 20 flights)

•

Lubricate gyro drive linkage with oil (every 20 flights)

•

Check pitch of gyro paddles (every 30 flights)

•

Check gearbox for cracks (every 30 flights)

•

Check bevel gear mesh (every 30 flights)

•

Power Train Maintenance

Check tightness of all bolts and setscrews on bearing blocks and gears (every 10 to

•

20 flights) Check all gear meshes (every 30 flights)

•

Field Equipment Maintenance

•

Make sure 12 volt battery for power panel is fully charged (every flying day, if applicable)

•

Check glow-plug clip wires for breaks or other signs of wear (every 30 flights)

•

Clean oil off field equipment (every flying day, oil attracts dirt and is eventually transferred to everything in your flight box)

Making Repairs with Fast Glass

Fast Glass is an easy way to quickly repair broken plywood and canopy parts. Fast Glass is simply a fiberglass patch made with CA glue and cured instantly with CA

accelerator. The following procedure describes how to make a small Fast Glass patch on a broken part.

Warning! Never try to repair flexible plastic parts such as any of the parts on the main rotor of

your Model 110 helicopter! No type of glue (including CA glue) will stick to the plastic, and THE REPAIRED PART WILL FAIL IN OPERATION AND POSE A SERIOUS

DANGER!

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Operator's Guide Zen and the Art of Helicopter Maintenance

1. Assemble the necessary supplies: Thick CA glue, CA accelerator, heavy fiberglass cloth, coarse sandpaper, a scissors and a small plastic bag (like the parts bags in your Model 110 kit).

2. Clean the broken part with window cleaner to remove any oil. Sand an area ½” (13mm) around the break with coarse sandpaper or a grinder to scratch the surface and remove any paint.

3. Cut a piece of heavy fiberglass cloth to fit the patch area.

Hint: Fiberglass cloth does not easily bend around sharp edges. If you are repairing

the plywood crutch on your Model 110, apply a separate patch to both sides of the plywood rather than trying to bend a single patch around an edge.

4. Hold the break tightly closed and apply thick CA glue to the surrounding sanded area.

5. Lay the fiberglass cloth patch over the CA glue, and fill the weave in the cloth with more CA glue.

6. Place the plastic bag over your thumb and spray CAaccelerator on the outside of the plastic bag. Press the plastic bag down onto the fiberglass patch and the CA glue will immediately harden.

7. Remove the plastic bag and you will have a smooth fiberglass patch. Trim the rough edges of the patch with a hobby knife or grinder.

Warning! If you grind fiberglass, wear a filter mask and do not inhale the dust! The sharp

glass fibers in the dust can settle in your lungs and cause long term health problems.

Making Repairs with CA and Baking Soda

Common baking soda (sodium bicarbonate) is a remarkably good filler material for thin CA glue. Baking soda not only fills small gaps, but also accelerates the hardening of CA glue (like liquid CA accelerator). To make a rapid repair with baking soda, simply clean and abrade the surface, cover or fill the area with baking soda to a depth of about 1/16” (1mm) and apply several drops of thin CA. The CA will soak into the baking soda and harden almost instantly. Fill deep holes in 1/16” (1mm) layers to insure that CA soaks through all of the baking soda.

Note that baking soda repairs are easy to shape with a hobby knife or sand paper, but are not as strong as Fast Glass. For high strength repairs, such as on the Model 110 plywood keel, use Fast Glass. For moderate strength repairs and to fill gaps, use baking soda.

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Operator's Guide Zen and the Art of Helicopter Maintenance

Fixing a Bent Tail Boom

Tail booms arefrequently dented by the main rotorblades during crashes or hard Tail booms are frequently dented by the main rotor blades during crashes or hard landings. Small dents will not affect the flight qualities of your Model 110. If a boom strike actually bends the boom, it can usually be straightened by hand several times before being replaced. Small dents can be removed by passing a 3/8” (10mm) wooden dowel rod into the boom to push out the dents. Generally, replace a tail boom at the first signs of cracking, or when the boom becomes so ugly you cannot stand it.

Straightening a Bent Main Shaft

Main rotor shafts are bent occasionally during crashes. The bend will almost always occur where the shaft is supported by the upper ball bearing.

To straighten a main rotor shaft, first disconnect the swashplate control linkages and remove the main rotor head from the shaft. Attach a pointer (made from a clothespin and paper clip wire) to the top edge of the crutch and set the pointer next to the top end of the main shaft. Rotate the shaft until you can see the direction in which the main rotor shaft is bent. Lightly press on the top end of the main shaft with your thumb in the opposite direction of the bend, then check the shaft for straightness again.

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Operator's Guide How Helicopters Work

ow Helicopters Work

By Paul Arlton

This section provides a brief technical explanation of certain aspects of helicopter flight control systems, and is included in this Operator’s Guide for your interest only. It is not necessary to read this section in order to build or fly your Lite Machines Model 110 helicopter.

Introduction

With all of their spinning gizmos and mechanical linkages, model helicopters are intrinsically interesting. Unfortunately, they can also be very expensive and complicated, and traditional model helicopters are not well suited for the average modeler. They usually require considerable patience and understanding (mostly from the other members of your family), and a credit card with a high limit. The Model 110 is meant tobe different from traditional model helicopters, and it’s designreflects the personalities of the people who were involved in its development: Dave Arlton, Paul Klusman and me, Paul Arlton.

As much as I enjoy helicopters, I don’t have the patience necessary to be successful with them. Even with airplanes, I rarely allocate adequate time for my projects, and end up immensely frustrated when things don’t work. So I concentrate on projects that are simple, inexpensive and less likely to end up as a psychological disaster. I am perfectly content with a simple two-channel Cox .049 powered F6F Hellcat that I built from scratch in a weekend from Styrofoam and Econocote for about $10.

My brother, Dave, is just the opposite. He revels in the complex and esoteric. In 1987, with dreams of spinning rotors and autorotations impairing his ability to reason objectively, he purchased a Shlüter Champion helicopter for about $1,600 (that’s in 1987 dollars). At the flying field he would wander aimlessly for 30 minutes, building enough courage to attempt his first flights of the day. I never had that problem with my F6F.

One day in 1988, our friend Paul Klusman brought over a rubber-band powered model helicopter he had designed. As I watched it fly, I though it must be possible to build something similar for radio control. Later, in 1990, after two years of experimentation and development work in the basement, we had a flying model helicopter powered bya Cox .049, andsought a company tomanufacture and market it. When Dave and I could not find a suitable company, we decided to build one ourselves. With the help of our parents, we incorporated Lite Machines in the Purdue University Research Park in 1991.

As we developed the prototypes that would eventually become the Model 110,we learned a lot more about model helicopters than we really wanted to know. Because we started with little formal education on the subject, however, we often argued about

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Operator's Guide How Helicopters Work

details without completely understanding the big picture. It would have been handy to start with a basic understanding of helicopters so that we could have discussed some of the problems more intelligently.

The following sections provide a brief introduction to helicopter flight dynamics for those who are just starting and want to know a little more.

Background and History

Helicopters are flying machines with the ability to hover and fly forwards, backwards, and sideways. This agility stems from the multiple capabilities of the main rotor system. Since the invention of helicopters in the early 1900’s, considerable effort has been expended advancing helicopter technology, with a substantial percentage of that effort concentrated on the main rotor system.

While the technology of full-size helicopters progressed for decades, model helicopters remained impractical for lack of suitable engines, radio control equipment, and construction materials. As the state-of-the-art in full size helicopters advanced in the 1950’s and 1960’s, many novel model helicopter designs were developed, but none proved practical. Model helicopter designers often copied the designs of full-size helicopters without understanding the basic differences between full-size and model aircraft. As a result, scaled-down model helicopters were typically unstable, uncontrollable and underpowered.

In the 1970’s hobbyists (most notably Dieter Shlüter in Germany) developed the first practical model helicopters. Lighter radio control equipment, more powerful engines and systematic engineering all contributed to early successes. Much of model helicopter design, however, is rooted in tradition. Even though helicoptertechnology has advanced considerably since that time, the designs and design philosophies of that era are still in widespread use.

Because the main rotor system of a helicopter is capable of performing so many flight functions, it is usually very complex mechanically. Model helicopters currently available contain myriad pushrods, mixing arms, bellcranks, ball joints, and expensive ball bearings, and the trend has been toward higher complexity and prices. High complexity and cost keep many model enthusiasts away from helicopters.

Standard Helicopter Configuration

Both model and man-carrying helicopters are commonly designed with a large main rotor which lifts the helicopter into the air. A smaller tail rotor mounted at the end of a tail boom counteracts the torque produced by the main rotor and steers the helicopter. Both main and tail rotors are driven by an engine usually located within the helicopter fuselage(body) near themain rotor shaft. A streamlined fuselage shell

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Operator's Guide How Helicopters Work

often covers the front half of the helicopter, but does not always extend backto the tail rotor because of the added weight and the complexity of attaching the rear shell to the rest of the helicopter.

From a distance, the main rotor of a helicopter looks superficially like a large propeller sitting on top of the fuselage. The main rotor blades do act something like a propeller or fan, and move large amounts of air downward creating a force that lifts the helicopter upward. Helicopter rotors, however, operate in a manner completely different from propellers on an airplane. Unlike propellers, they are designed to move through the air sideways. In order to control a helicopter in horizontal flight the pilot causes the main rotor to tilt slightly in one direction or another. The offset lift force produced by the tilted main rotor causes the helicopter to move in the direction of the tilt.

Main Rotor Control

To understand generally how helicopter main rotor systems work, it is easiest to begin with a simplified representation of a rotor system. Fig. 5-1 shows a schematic rotor blade rotating about a shaft. The rotor blade pitch axis runs down the length of the rotor blade. Blade pitch (also called “angle of attack”) is considered positive when the leading edge of the rotor blade is rotated upward about the pitch axis. The aerodynamic lifting force produced by a rotor blade is related to blade pitch. Increased (positive) pitch corresponds to increased lift.

Pitch angle

Figure 5-1.

Pitch axis

Leading edge

Rotor blade

Rotor shaft

Rotation direction

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Operator's Guide How Helicopters Work

As shown inFig. 5-2, inaddition to apitch axis, rotorblades are generallyhinged near the rotor hub to allow the blade to flap upand down and swing forward and backward. This allows the rotor blades to react to the constantly changing aerodynamic and gyroscopic forces encountered in flight. Without these hinges the rotor blades would likely be unstable, and would need to be built stronger and heavier to withstand in-flight forces.

Flap up

Blade lead

Flap down

Lead/lag axis

Blade lag

Flapping axis

Rotation direction

Figure 5-4.

Helicopter dynamics are substantially different from airplane dynamics. The rotating main rotor on top of a helicopter acts like an immense gyroscope. As such, the rotor obeys the physicallaws of gyroscopes. The basic operating principles of gyroscopes are not obvious, so read the next sentence over a few times because this rule-of-thumb is the key to understanding gyroscopes and helicopters.

Forces applied to tilt a rotating gyroscope produce motion 90 degrees later in the direction of rotation.

Why? Because the gyroscope is rotating. If the gyroscope was not rotating, the forces would cause it to tilt where the forces are applied. Since the gyroscope is rotating, it starts to tilt where the forces are applied, but the rotational motion effectively carries the tilting motion along with it. The maximum tilt actually occurs 90 degrees later in the direction of rotation.

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Operator's Guide How Helicopters Work

Flap up

90 degrees

Aerodynamic force

Rotation direction

Flap down

Figure 5-3.

The rule-of-thumb for gyroscopes is illustrated by Fig. 5-3 , if aerodynamic forces are applied to a pair of rapidly rotating rotor blades, the rotor blades, acting under the laws of gyroscopes,will flap 90degrees later inthe direction ofrotation. This flapping will be seenby an observer asa tilt of theentire rotor disk (when arotor rotates at high speed, it is difficult for an observer to discern individual rotor blades, the rotor appears to be a transparent disk). The aerodynamic forces are created by changing the pitch of the rotor blades, or by air turbulence.

On the Model 110 for instance, to tilt the rotor disk backward, the main rotor blades are pitched to a high angle of attack as they pass around theright side of the fuselage and to a low angle of attack around the left side of the fuselage. The aerodynamic forces produced by this difference in angle of attack cause the blades to flap upward 90 degrees later over the nose and downward over the tail boom thereby tilting the rotor disk backward.

Why 90 degrees, and not some other angle like 62 degrees or 127 degrees? The answer is fairly technical, and involves the concept of mechanicalresonance which is a kind of back-and-forth motion such as the motion of a weight swinging on the end of a piece of string. But, forgetting the technicalities, think of it like this: there is no good reason why the point of maximum flapping should be any closer to one of the forces than to the other. If the two forces are located opposite each other (180 degrees apart), then the maximum flap angle should occur right in the middle at 90 degrees.

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Operator's Guide How Helicopters Work

Since the main rotor on a helicopter rotates while the fuselage or body of the helicopter does not, some mechanism is needed to transmit control commands from the non-rotating pilot to the rotating main rotor blades. One such mechanism is called a swashplate which is essentially a large ball bearing assembly surrounding the main rotor shaft. In order to tilt the main rotor, the pilot moves linkagesattached to the lower half of the swashplate. The upper half of the swashplate is connected through linkages to the rotor blades.

Traditionally, the pilot of a full size helicopter controls the main rotor by manipulating a joystick called the “cyclic” control located in front of the pilot, and a lever called the “collective” control located to the left of the pilot. Cables, pushrods, and bellcranks connect the cyclicand collective controls through the swashplate to the pitch controls of the main rotor blades. Main rotor systems of most radio-controlled model helicopters operate in an manner similar to full-size helicopters. The pilot manipulates small control sticks on a hand-held radio transmitter which in turn sends commands to servo actuators located within the flying model. Pushrods and bellcranks connect the servos through the swashplate to the pitch controls of the main rotor blades.

To bank the helicopter to the right or left, or move forward or backward, the rotating rotor blades are pitched upward as they pass around one side of the helicopter and downward around the other. This is called “cyclic” pitching since the rotor blades cycle up and down as the rotor rotates. The difference in lift produced on either side of the helicopter causes the main rotor blades to flap up and down, and the rotor disk appears to tilt. The tilted rotor disk produces a sideways thrust forcethat then pushes the helicopter in the direction of the tilt.

The large size and high inertia of most helicopter rotors means that they cannot change speed quickly. For this reason, they are usually designed to operate at a nearly constant rotational speed at all times. To control main rotor lift, the main rotor blades are pitched upward or downward in unison. This is called “collective” pitching since all rotorblades move together. The change in pitch, and associated lift force, of the rotating rotor blades causes the helicopter to gain or loose altitude.

Some small model helicopters (such as the Model 110) rely on variable engine speed instead of collective blade pitch for altitude control since main rotor thrust is proportional to engine speed as well as blade pitch. The main rotor blades on these models are typically built at a fixed pitch (relative to each other) and are light enough to react quickly to changes in engine speed. The primary advantage of fixed-pitch rotors on models is reduced mechanical complexity and cost.

Main Rotor Stability

Flight stability is often a problem for small helicopters. To improve stability, weighted stabilizer bars (flybars) are usually incorporated into model helicopters, but are uncommon on modern full-size helicopters. First patented by Stanley Hiller Jr. in 1953 and refinedfor use onmodels by Dieter Shlüter in 1970, these flybars are tipped with aerodynamic paddles (Hiller paddles), and are connected through linkages to the swashplate and main rotor blades.

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Operator's Guide How Helicopters Work

Because the pilot’s controls are attached to the flybar, and not directly to the main rotor blades, Hiller control systems naturally exhibit a slight control delay. A hybrid stabilization system referred to as the Bell/Hiller system incorporates additional linkages to mix direct rotor blade control with flybar stabilization. The Bell/Hiller system responds quickly to pilot control since control commands are transmitted directly to the main rotor blades, while the system is stabilized by a Hiller-type flybar and paddles.

A major drawback of flybars and paddles is increased aerodynamic drag. The circular cross-section flybar wire supporting Hiller paddles can produce more drag than the paddles. Moreover, since Hiller paddles are typically configured to operate at a zero angle of attack relative to the rotor head, and since air passing through the rotor is almost always flowing downward, Hiller paddles can actually operate at a negative angle of attack with respect to the incoming airflow. In this way, Hiller paddles may actually contribute negative lift.

The unusual Arlton Subrotor stabilizer blades on the Model 110 serve a triple purpose. As part of the main rotor control system, they amplify pilot control commands to the main rotor blades. As part of the stability system, they act to keep the main rotor spinning in a constant plane in space. As rotor blades, they can produce lift that reduces or eliminates the reversed airflow commonly found near the rotor hub.

Retreating-Blade Stall

Retreating-blade stall (also referred to as “asymmetric lift”) affects helicopter rotors that are moving forward (translating). As the Model 110 moves forward, the blade swinging forward over the right side of the helicopter (the advancing blade) experiences a higher air speed than the blade swinging backward over the left side of the helicopter (the retreating blade). At high airspeeds the advancing blade generates high lift,while the inner portionsof the retreatingblade are actually moving backward relative to the oncoming wind and much of the retreating blade is stalled. The airflow around the stalled retreating blade is very turbulent and the blade does not generate much useful lift.

Following the rule-of-thumb for gyroscopes, the high lift generated by the advancing blade, and the low lift produced by the retreating blade will cause the main rotor disk to tilt backward away from the oncoming wind. In order to keep the Model 110 moving forward at high speed, the pilot has to maintain forward pressure on the transmitter fore-aft cyclic control stick to reduce asymmetric lift and tilt the rotor disk forward.

Retreating blade stall can also be induced by changes in rotor speed. Since the Model 110 has a fixed-pitch (variable-speed) main rotor, the speed of the rotor must change to controlaltitude. When descending from altitude the speed of the mainrotor is reduced substantially, but forward flight speed does not change. Without pilot intervention, the Model 110 will pitch up and fly backwards due to retreating blade stall. It should be noted that helicopters with collective-pitch (constant-speed) main rotor systems do not experience retreating blade stall during descents and do not require much forward stick pressure to maintain forward speed.

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Operator's Guide How Helicopters Work

Anti-Torque Systems

The torque (reaction force) created by rotating the main rotor of a helicopter in one direction tends to cause the body to turn in the opposite direction. When trimmed for steady hovering flight, the tail rotor at the end of the tail boom creates enough thrust force to balance the torque produced by the main rotor so that the helicopter maintains a constant heading. Decreasing or increasing the thrust force of the tail rotor causes the helicopter to turn in one direction or the other.

The pilot of a full size helicopter controls the tail rotor by manipulating foot pedals located within the cockpit. The pilot of a model helicopter manipulates control sticks on a radio transmitter which in turn sends commands to servo actuators located within the flying model. Cables, pushrods, and bellcranks connect the pedals or the servos to the pitch controls of the tail rotor blades. The pilot adjusts the pitch and associated thrust force of the rotating tail rotor blades to turn the helicopter.

Although a number of modern anti-torque systems (such as blown tail booms and shrouded fans) havebeen developed, tail rotors have not changed materially for over 25 years. For reasons of structure and simplicity, and to minimize actuation forces, tail rotor blades traditionally employ symmetrical cross sections such as a NACA 0012 airfoil, and simple constant-chord blade shapes. While easy to build, these rotors do not utilize power very efficiently. Since helicopters have relatively low payload capacities, even small increases in rotor performance can result in large percent changes in payload capacity.

Cambered (curved) airfoils can substantially increase the lifting potential of a rotor blade. Cambered airfoils, however, have a drawback: the curvature of the airfoil causes the airfoil to pitch downward toward negative angles of attack. This pitching tendency can cause the rotor blade to twist and exert high loads on the blade pitch-control linkages (and consequently to the pilot’s legs in full-size helicopters, or to the servos in model helicopters).

The unique swept tail rotor blades on the Model 110 balance the aerodynamic twisting forces of high lift cambered airfoils with other forces. They operate something like canards (little forward wings) on an airplane by balancing the negative twisting force of cambered airfoils with a positive lift force located in front of the blade pitching axis. Small counterweights at the blade root also help to balance the aerodynamic forces. As a result, tail rotor power requirements are lower, and control linkage forces are reduced by as much as 80%.

Gyro Stabilizers

In general, maintaining a constant heading in hover or low speed flight can be a difficult business for a helicopter pilot. To counterbalance the constantly changing forces on the helicopter fuselage produced by changes in engine torque and

5-8 LITE MACHINES

Operator's Guide How Helicopters Work

atmospheric conditions such as wind gusts, the pilot must continually manipulate the tail rotor controls. This is especially true for models because of their small size and low mass, and the resulting tendency to react rapidly to disturbances.

To solve this problem, practically all modern model helicopters are equipped with some sort of auxiliary stabilization system. A gyroscopic stabilizer, or “gyro”, is a device on a helicopter that senses turning motion, and then automatically controls the tail rotor to slow or stop the turn. Basically, a gyro keeps the tail of a model helicopter from swinging around so that the pilot can concentrate on other things.

The gyro systems most common today actually consist of two separate units: a rotation sensing mechanism and an electronic amplifier. The sensing mechanism commonly includes metal disks rotated at high speed by an electric motor and contained within a small plastic box about 1-1/2" (38mm) on a side. The disks tilt whenever the helicopter turns. The electronic amplifier senses this tilt and sends an electronic signal to the tail rotor servo which adjusts the thrust of the tail rotor to stop the turn. Electro-mechanical gyro systems are typically heavy, expensive and require substantial battery power to operate. These systems are too large and too heavy to work with the Model 110, and since they constantly adjust the tail rotor during flight they tend to accelerate wear on the tail rotor servo.

The Arlton Gyro stabilizer, on the other hand, is a small, simple mechanical mechanism that attaches to the tail rotor of a helicopter and performs the same function as an electro-mechanical gyro. It operates under the same physical laws governing electro-mechanical gyros (seethe rule-of-thumb for gyroscopes under the Main Rotor Control heading in this chapter), but it is driven and amplified mechanically rather than electronically. It weights only about ½ ounce (14 gm), consumes no battery power, and is standard equipment on the Model 110. Since the Arlton Gyro stabilizer controls the tail rotor blades directly, it does not affect the workload of the tail rotor servo.

LITE MACHINES 5-9

Operator's Guide How Helicopters Work

Z-link delta angle

Z-link

Drive link

Pitch-change spider

Spider

Ta il r otor pushrod

slider

Spider slider pin

Drive link

Drive link pin

Pivot pin

Z-link

Gyro mount

Gyro hub

Gyro spindle

Paddle grip

Gyro paddle

Figure 5-4.

The aerodynamic paddles and gyro hub on the Arlton Gyro stabilizer are supported for rotation by a gyro spindle (see Fig. 5-4) which is free to tilt about two small, steel pivot pins. The pins are connected to a gyro mount which is secured to the end of the tail rotor pushrod on the Model 110. The pushrod extends through the hollow tail rotor shaft (see Fig. 5-5). When the body of the helicopter turns, the pivot pins turn with the body and apply forces to the gyro spindle to tilt the paddles about a vertical axis in the direction of the turn. Following the rule-of-thumb of gyroscopes, the paddles actually tilt 90 degrees later about a horizontal axis. As they tilt, they displace linkages (including the spider slider and the pitch-change spider) which change the pitch of the tail rotor blades. This change in blade pitch modifies the thrust produced by the tail rotor, and slows or stops the turning motion of the helicopter.

Left to themselves, the gyro paddles will remain tilted unless the helicopter starts turning in the opposite direction. But the small Z-links that connect the paddlesto the tail rotor are angled slightly at one end (see Fig.5-4) so that the pitch of the paddles changes as the paddles tilt. This change in paddle pitch generates aerodynamic

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Operator's Guide How Helicopters Work

restoring forces onthe paddles thatpush them backto their initial, untilted orientation (helicopter buffs will understand that this is similar in concept to delta hinges on a main rotor). So, essentially, turning motion of the helicopter causes the paddles to tilt, and the tilted paddles then push themselves upright.

Gyro hub

Pivot pins define horizontal tilt axis

Gyro tilt

Arlton Gyro stabilizer

Drive links expand and contract

Ta il r ot or gearbox

Tail rotor blade

Ta il r ot or pushrod

It is interesting to note that the gyro mount may be oriented on the tail rotor pushrod so that the pivot pins are not horizontal. In this configuration, the gyro will sense rolling motions as well as turning motions. In this way the gyro can be set to coordinate turns by modifying the thrust of the tail rotor when the helicopter rolls. This is something like adding rudder when turning an airplane with ailerons.

Change in blade pitch due to gyro tilt

Figure 5-5.

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Operator's Guide How Helicopters Work

Gyro paddle (not tilted)

Drive link

Small blade weight

Gyro hub

Pilot control moves gyro

Hollow shaft

Tail rotor gearbox

Tai l ro to r pushrod

Bellcrank

Pilot control pushrod

Tail rotor blade

Change in blade pitch due to pilot control

Figure 5-6.

The Arlton Gyro stabilizer works automatically without any input from the pilot, but at some point the pilot may wish to trim the tail rotor or turn the helicopter without interference from thegyro. To turn the helicopter, the pilot controls thetail rotor servo which moves the tail rotor pushrod back-and-forth. As shown in Fig. 5-6, the tail rotor pushrod passes from the right side of the gearbox completely through the hollow tail rotor shaft and extends out the left side. Since the gyro is mounted to the end of the pushrod, the entire gyro assembly moves back-and-forth along with it.

The rule-of-thumb for gyroscopes states that a gyro will react to tilting forces, but the rule says nothing about moving the whole gyro back-and-forth. In fact, linear (non-tilting) motion ofthe gyro has noeffect on the gyrowhatsoever. This means that the gyro will not tilt, and will not change the pitch of the tail rotor blades when the pilot moves the tail rotor controls. The gyro will operate only when the body of the helicopter turns.

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Operator's Guide How Helicopters Work

When the helicopter starts to turn under pilot control, the gyro will tilt about 20 degrees before reaching an end limit. Once there, it will no longer be able to modify the pitch of the tail rotor blades, and so it will stop opposing the turn. This means that after the helicopter turns a certain amount, the pilot will have amplified tail rotor control authority (something like having dual-rates on the transmitter).

The aerodynamic and mechanical characteristics of the tail rotor have a substantial impact upon the operation of the Arlton Gyro stabilizer. The actuating power of a purely mechanical gyro stabilizer is determined by the rotational speed, size and mass of the gyro paddles and gyro hub. Given a particular tail rotor rotational speed, high actuation forces require large diameter and/or heavy gyro paddles. Tail rotor blade actuation forces, therefore, must be kept low to minimize the size and weight of the gyro.

Undercambered airfoils can greatly increase the thrust of the tail rotor, but the pitching forces generated by undercambered airfoils can also exert high loads on the tail rotor blade pitch-control linkages, and consequently on the gyro. The tail rotor blades on the Model 110 are aerodynamically and centrifugally balanced to operate in conjunction with the Arlton Gyro stabilizer. Small weights are provided at the root of each blade for fine tuning the pitching forces. If the blades are not completely pitch-balanced, the gyro will tilt slightly even when the helicopteris not turning. In this case, the small weights should be replaced with lighter or heavier weights until the gyro no longer tilts noticeably.

The Arlton Gyro stabilizer on the Model 110 is only one member of a family of simple mechanical gyros. Over 20 variations have been developed to suit various helicopter configurations. With certain modifications to the structure of the helicopter, the gyro may be located oneither side of the tail rotor, on the gearbox oppositethe tail rotor, or elsewhere on the helicopter. Since the gyro can be adapted to produce a thrust force like that produced by the tail rotor, some configurations have multiple rotors, while others omit the tail rotor entirely and have only a single gyro-rotor. All of these variations, along with the other unique features of the Model 110, are either patented or patent-pending in the United States and countries all over the world.

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Operator's Guide Specifications, Model 110

pecifications, Model 110

241 mm (9.5”)

71 mm

(2.8”)

163 mm

(6.4”)

610 mm (24.0”)

191 mm (7.5”)

43 mm (1.7”)

671 mm (26.4”)

140 mm (5.5”)

Figure 6-1.

General

•

Weight, no fuel: Approximately 28 oz (795 gm)

•

Weight, full fuel: Approximately 30 oz (852 gm)

•

Max. gross weight: Highly dependent upon engine and flight

conditions

•

Operating temperature range: 35°F to 95°F (2°C to 35°C)

Main Rotor

•

Main rotor blade type: Semi-flexible, twisted, tapered,

•

Main rotor blade suspension: Dual flapping with no mechanical

•

Main rotor diameter: 24 in (607 mm)

•

Subrotor stabilizer diameter: 9.5 in (241 mm)

•

Main rotor blade area: 29.2 in2(188 cm2)

•

Subrotor stabilizer blade area: 10.4 in2(67 cm2)

•

Useful blade area: 39.6 in2(255 cm2)

•

Disk loading (max. fuel): 0.6 lb/ft2(2.9 kg/m2)

•

Blade loading (max. fuel): 6.8 lb/ft2(33 kg/m2)

undercambered, three airfoil sections

damping (DF), foldable about flapping axis

LITE MACHINES 6-1

Operator's Guide Specifications, Model 110

Power loading (max. fuel): 13.7 lb/hp (8.3 kg/kw)

•

Continuous main rotor speed: 1900 rpm

•

Max. (never-exceed) rotor speed: 2000 rpm

•

Figure of merit: 0.5 to 0.6 (requires estimate of actual power

•

and maximum gross weight at sea level)

Tail Rotor

Tail rotor blade type: Dynamically Over-Balanced (DOB),

•

semi-flexible, twisted, tapered, undercambered

Tail rotor diameter: 7.5 in (190 mm)

•

Tail rotor blade area: 5.5 in2(35.5 cm2)

•

Continuous tail rotor speed: 3990 rpm

•

Maximum tail rotor speed: 4200 rpm

•

Arlton Gyro rotor diameter: 5.5 in (140 mm)

•

Engine/Transmission

• Engine: Norvel Vmax-6 (with throttle/muffler)

•

Max. rated engine power: approx. 0.13 hp (100 W)

•

Max. rated transmission power: approx. 0.13 hp (100 W)

•

Max. engine rpm: 22,700

•

Engine/main rotor gear ratio: 1 : 11.3

•

Tail rotor/main rotor gear ratio: 1 : 2.1

•

Maximum fuel capacity: 2.3 oz (67 cc)

•

Nominal fuel capacity: 2.0 oz (57 cc)

Note: The foregoing specifications are provided for interest only, and are not meant to be a

basis for considering the Lite Machines Model 110 helicopter for any particular application.

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Lite Machines 110 Operator's Manual

Specifications and Main Features

Frequently Asked Questions

User Manual