McKELLAR AERO DESIGN Gee Bee Z Construction Manual

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Gee Bee Z

Construction Manual

McKELLAR AERO DESIGN

Wingspan: 28” Wing Area: 128 in² Weight: 8.5 oz

Power: GWS IPS-A gearbox with Medusa 012-

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030-4000

prop) OR small outrunner

brushless motor (30-40W with 8X6

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Table of Contents

Introduction…………………………………….…………..……2 Kit contents…………………………………….……………..….2 Required to complete……………………….……………...2 General building instructions………………...………3 Building the vertical and horizontal tail………3 Building the wing………………………..………..…………..4 Building the cowl……………………………………….……..5 Building the fuselage…………………….……….……..…7 Building the wheel pants………….…………….……….17 Recommended equipment………………………………..20 Final assembly……………………………………………………21 Prepare for flight……………………………….……………22 First flight……………………………………….……………….22

Introduction

Thank you for purchasing this model kit. We have worked very hard to provide a model that is both easy to build and fly. Please read through all the instructions before you begin building so that errors can be avoided.

Kit Contents

• Four sheets of laser cut 1/16” balsa

• Three sheets of laser cut 1/32” balsa

• One sheet of laser cut 1/8” balsa

• Two sheets of laser cut 1/4” balsa

• One sheet of laser cut 1/8” light plywood

• One sheet of laser cut 1/32” plywood

• Vacuum formed canopy

• Plans

Required to Complete

• 0.032” music wire

• 0.047” music wire

• Two plastic tubes (Evergreen Plastics 3/32” styrene tubes)

• Two 1/8” diameter by 1/16” or 1/8” long rare-earth magnets

• Two Dubro Micro E/Z Connectors

• 8-32 nylon bolt

• Covering (Nelson LiteFilm or equivalent)

• Self-adhesive Velcro (can be found at most hardware stores)

• Medium and thin cyanoacralate (CA)

• 10 minute epoxy

• Three micro servos weighing 6-8g with 8-10 oz-in torque rating

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• One micro receiver

• Motor: 12mm brushless motor (4000Kv) in GWS IPS-A gear box

Or a small outrunner.

• One speed control with BEC (battery elimination circuit) suitable for your motor.

General Building Instructions

• It is best to remove the parts from the laser cut sheets only as they are needed. This will reduce any chance of confusion since some of the smaller parts are not labelled on the actual part.

• Write the part numbers on the parts as they are removed from the sheets (only mark the back sides of sheeting parts as ink will show thru the covering.

• Sand down any remainders of the tabs which held the parts in the sheet.

• Do not force any tabs into the slots. Enlarge the slots if the tabs are a bit tight. A

jewellers file or nail file works well for this.

• Be sure to check the fit of each part and assembly before applying glue.

• Use medium CA for all joints unless told otherwise.

Building the Horizontal and Vertical Tail

The fin, rudder, stab and elevators are built up over the

plan. Fit all the parts in position and apply some med CA to all the joints. Once all the glue has cured, you can remove the fin from the building board. Lightly sand both sides so they are flat with no lumps. The leading edge and tip should be rounded over with a sanding block. Mark the hinge locations and cut the hinge slots with an Exacto blade. Make the holes for the elevator joiner wire and finally, sand the leading edge of the rudder and elevators to a 30° angle.

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Building the Wing

R1A R2

4/R3/R4

R10

W17

W12

W13

W15

Remove all the wing ribs and spar parts from the parts sheets. Sand R3 down slightly so it is the same thickness as the 0.047” landing gear wire. Make the R4/R3/R4 laminations and then fit all the ribs in place on the lower spar (W1). Now carefully press the top spar (W2) in place over the ribs. Glue WI and W2 together which a bad of CA at the join line. Do not glue the ribs to the spar yet.

Now, glue together the lower sheeting pieces making sure that they are flat and fit well.

The spar/rib assembly is now fit in place making sure that all the rib tabs fit in the sheeting slots. Once everything is fitting nicely, apply CA. There is no need to apply glue to the whole joint. A few dabs will work fine. Remember, too much glue adds weight!

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R11B

W10

W15

Glue the root ribs in place and be sure to glue W18, W11 and R14 in both wings before applying the top sheeting. Use the aileron torque rod to line up R14 before gluing it.

Now, take the spar joiners (W4&W5) and test fit them in place. When you are happy with the fit remove them and glue the top sheeting in place making sure there is no twist in the wing.

Sand the leading edge sheeting flush with the ribs and glue on the leading edge (W15). Next, glue the wing tip in place along with the last wing rib (R11B and R11A). Now sand the leading edge round and sand the trailing edge of W12 and W15 down to follow the contour of the wing ribs. Use some masking tape on The wing ribs to protect them during this stage.

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W16

R9B

R8B

R8C/R8D/R8C

R7B R6B

The ailerons are pretty simple, just fit all the parts in place and apply some CA to the joints. Sand the top side of W16 so that is follows the profile of the aileron ribs. Again, use masking tape on the ribs to protect them. The final step for the ailerons is to sand the leading edge into a V shape centered on the hinge line. This bevel only needs to be about 25° on either side of the hinge line. This bevel will allow the ailerons to pivot about the hinge line.

Sand the leading edge of the wing panels to the final shape and then test the fit of the wing joiners (W4 and W5) in both wing panels. Glue the joiners in one panel and let cure. Finally, glue the two wing halves together at the root rib and wing joiners.

Building the Cowl

Start the cowl by building the two rings made up from C4A and C4B parts. These two rings are identical.

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1/8” square

Cowl sheeting

Overhang

Now, pin one cowl ring to your building board and fit the cowl rings together with the parts C1, C1, C2 and C3. Use a square to make sure the ring edges line up and apply glue to the joints. Now, fit in place the 1/8” square stock that has been cut on the 1/8” balsa sheet. Make sure these sticks are the correct length before gluing in place.

The cowl sheeting is installed next. Note that this sheeting will overhang C4A/C4B ring a little. The cowl can be removed from the building board after the sheeting is applied.

Now, flip the cowl over, cut off the building tabs on C1, C2 and C3 and glue on the ¼ balsa rings and then sand to shape. Take your time and you will end up with a nicely shaped cowl

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F6B F8B

F20

Building the Fuselage

Start with the fuselage sides. F2 is the right side and F1 is the left side. Note that F2 is shorter than F1 due to the right thrust built into the firewall. Make sure you glue the formers on the correct sides and double check before gluing in place.

Fit F20 in place between F6B and F7B and glue in place using a square to ensure it is perpendicular to the fuselage side.

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Place F6G and F8E in place on F4 and glue in place. Be sure that you glue these on the

F10D

F9D

F8D

F7D

F6D

F6G

F8E

Short side

F10C

F9B

F10B

F22

F9C

F9B

correct side of F4.

Fit the fuselage sides in place on F4 and glue in place. Now fit the center former pieces shown in the photo below. Check the plan for proper orientation of these parts. Use a square to make sure the aft ends of the fuselage sides (F1&F2) are perpendicular to the bench.

Now, fit the aft former sides and bottoms as well as the light ply wing bolt plate (F22)

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F9A

F10A

Fin Assembly

1/16”X1/8” balsa

The rear top formers are now glued in place.

Fit the fin assembly in place making sure it lines up well with the after end of the fuselage

and glue in place. This is when you will need all those 1/16”X1/8” stringers. Fit the first stringer in place as shown below. Note that this stringer will be flush with the former edges as it supports sheeting. Now is a good time to install the plastic tubes for the pushrods.

Take a good look at the photo in on the next page for the stringer installation around the

cockpit. The top two stingers point out are to support the cockpit sheeting. The front end fits in notches but the rear end is just but glued next to the slot in F9A

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Stick buts up to former F9A flush with edge. This will support

Taper this end

Sand these ends flush

sheeting. All other stringers fit in slots.

Continue on with the other stingers and sand a taper on the rear end of the stringers. Note that the forward end of the stringer must be sanded down flush with the edge of F7B so that the sheeting will lie flush with the surface of the stringers.

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Once all the side stringers are applied it is time to install the wire tailskid. Then the belly stringer can be glued in place. You will have to taper the back end of them so they all fit.

Wire skid goes here Note: hole pre-cut for wire

Next, you must fit the wing in position and drill two 1/8” diameter holes through the two

pre-cut holes in F6D and into the wing. These holes are for the 1/8” dowel used to secure the front of the wing. Fit the dowels (1/2” long) in place so they are just a little proud of F6D, remove the wing and glue these dowels in place with thin CA.

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F12

Next, the fairing strip (F12) that goes around the stab is installed. The best way to do

this is to temporarily fit the stab in place and use it to line up F12. This may take a little sanding to get a good fit but take your time and it should come out well. Now install the pushrod fairings making sure you put them on the correct side. Use a 0.032” wire to line them up in the correct location as shown in the second photo on the next page.

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F12

F14

F13

Notch to sheeting

The photo below show the finished stringers on the top section of the fuselage. Please note which stringers need to be notched to the edge of the former for the sheeting.

It is now time to start sheeting the fuselage. First step is to glue F16A and F16B together. This is the sheeting that will go over the cockpit area. The dashed lines are to aid cutting out the cockpit hole later on.

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F16B

F16A

F15

Scrap 1/32” balsa

F17B

F18B

F19B

F17A

F18A

F19A

F17C

F18C

F19C

Sanded to sh

ape

The front nose rings are now glued on and sanded to shape

Now take the wing and fit in place on the fuselage. Use a 3/32” drill bit to drill thru the top side of the

wing using the bolt hole in F22 as a guide. Now enlarge these two holes with a 9/64 drill bit. Take W17 and cut threads in the hole using a 6-32 tap. When finished, apply some thin CA to the threads and let cure. This will harden the threads so they last longer. Now fit the wing back in place and use the 6-32 nylon bolt and W17 to bolt the wing in place. When your happy with the fit of everything, use some epoxy to glue W17 to the wing. Be sure you don’t glue the bolt in place. Some petroleum jelly on the threads will help prevent this. While the wing is attached, the belly formers (F8C, F7C, F6C) can be installed along with the central stringer. Remove the wing and add the remaining belly stringers (all 1/16”X1/8”)

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W19

F8C

F6C

F7C

F8F

F6A

F7A

F23

The battery hatch is built next. Note that you must sand down the edges of F5 so that it

follows the contour of the formers before you apply the sheeting. The central stinger is 1/8” square balsa from the strips cut in the 1/8” thick parts sheet. The other two stringers are 1/16”X1/8” balsa. Check the fit of the hatch before gluing the F23 clips in place. When the fit is good, glue both F23 in place.

Hole for magnet

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Apply the 1/32” balsa sheeting to the hatch in four sections, one between each stringer.

L1A

L1B

L3A

L3B

L2A

L2B

There is a slight compound curve to this hatch so one or two sheets will not work. The sheeting is cut from the extra wood on the 1/32” balsa parts sheet. Glue the sheeting to F5 first. This will keep the hatch from warping as you continue sheeting. Once the sheeting is done you can glue the 1/8” diameter magnets into the pre-cut holes in F5 (hatch) and F4 (fuselage). Make sure these magnets are oriented so that they will attract each other or the hatch will not close!

Glue this edge first

Building the Wheel Pants

The final step is to build the wheel pants. First, glue the inner parts together.

Now, make up the wire gear legs using the drawing as a pattern. When that is finished glue together the L1A/B and L2A/B parts. Next, remove the tabs from the slots in L1A/B clean

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the wire gear legs well and glue in the slots. Use the wheel to make sure the main gear wire

Main gear wire

Rear gear wire

2” wheel

L3A/B

is located correctly before gluing.

Now glue L3A/B onto L1A/B so that L1A/B is sandwiched between L2A/B and L3A/B.

Glue L4 on both sides of the landing gear assembly.

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You must make a groove in one L5 so that the wire leg will fit in it. Then glue in place.

Groove

The L6 wheel spacers may need to be sanded down a little depending on the width of you wheel. These will keep the wheel running in the center of the pant. Apply thin CA to the surface of L6 once they are glue in place. This will harden the surface and keep the wheel from wearing them down.

Glue the final L5 part in place and now you can start carving and sanding. Take your time and it should turn out well.

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Finished wheel pants ready for covering.

PLY DISKS

Recommended Equipment

The prototype uses the Medusa Research MR-012-030-4000 in the GWS IPS-A gearbox (5.9:1 ratio) with an 8X6 prop and 300 mah 3S (11.1V) lipo battery. This combination provides very good power and is quite light. A small outrunner style motor would work well for this model and the firewall has center lines etched in place to help locating it. There are small ply disks included on the 1/8” ply sheet to help in adjusting the distance of the motor depending on what you choose. Be sure to use mounting screws that go all the way through the disks and into the firewall.

Servos used are the GWS Pico servos but anything in that size and power range will work. A short antenna (base loaded) is recommended since this model since it is so short.

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Final assembly

CA HINGE

I used Nelson Litefilm to cover the model but you can use whatever light weight covering you prefer. A full set of vinyl graphics including all the wing and fuselage scallops and markings are available from Callie Graphics in Albuquerque, NM. You can contact them via their website http://www.callie-graphics.com/ or by phone at 505-293-2922. I highly recommend this graphics package as they are very high quality and really make the model stand out. If you are using a film covering and the graphics package most of the plane will be covered in yellow with only the cowl, belly section on wing and forward rim on fuselage covered in black. After all the covering is complete you can install the aileron torque rods, control horns and ailerons. For control surface hinging use standard CA type hinges and cut strips of about 1/16” width. Fit the aileron torque rod in place and slip the control horn over the torque rods. Use epoxy to glue the horns to the torque rod. Now fit the hinges in the aileron and apply epoxy to the torque rod slot in the ailerons. Fit the ailerons in place making sure they are centered and apply some thin CA to the hinge strips. Now, take some small spring clamps or cloths pins and lock the ailerons flush with the wing. Line up the control horns and set aside to cure.

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AILERON CONTROL HORNS

Now glue the wheel pants in place by applying some glue in the slot for the wire legs. Use epoxy for this and make sure the legs are set at the correct angle. The canopy is glue on with canopy glue once it has been trimmed to fit. Finally, mount the motor and glue in place the cowl. Install the servos, pushrods and battery tray F21 between F6D and F8D. Use Velcro on the battery tray and batteries to keep the batteries in place.

Prepare for flight

Support the wing at the location shown in Appendix B and place the receiver, speed control and battery in position so that the plane balances level. You should be able to achieve this balance point by shifting the battery fore and aft. Do not fly the plane with the balance point further aft than the indicated range. A tail heavy plane is unstable and extremely difficult to fly. Set the control throws as shown on the plan sheet and take off using the low rates.

First flight

Be sure to do a range check before the first flight to make sure the radio is operating properly. Check once again that the control surfaces are moving in the correct direction when the transmitter sticks are moved. Hand launching is not recommended with this plane. Use a good surface like pavement to take off from. Once airborne, get a feel for the plane and try a few approaches to get ready for the landing. Keep a little bit of power on until just before touchdown for a smooth landing. I hope you will have many enjoyable flights with this new plane!

Good flying!

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