Hangar 9 B-25 Mitchell ARF Assembly Manual

B-25 Mitchell ARF

Assembly mAnuAl

Specifications

Wingspan .....................................80.7 in (2050mm)

Overall Length ..............................63.0 in (1600mm)

Wing Area ............................851 sq in (54.9 sq dm)

Flying Weight ............. 13.5–15.5 lb (6.1 kg–7.0 kg)

.........................................(glow 2-stroke or electric)

Engine Size .................32–.40 2-stroke glow engine

Motor Size ................ Power 46 BL outrunner motor

Radio..........................................6 channels or more

Servos .... 10 servos (11 for glow version w/retracts)

...............(8 servos, 9 for electric version w/retracts)

Table of Contents

Using the Manual ............................ 3

Required Tools and Adhesives .................. 3

UltraCote Covering Colors ..................... 3

Before Starting Assembly ...................... 3

Radio and Power Systems Requirements .......... 4

Required Servo Extensions ..................... 4

Recommended JR, JR SPORT and

Spektrum Systems ........................... 5

Recommended Setup–Glow .................... 5

Recommended Setup–Electric .................. 5

FS One
(Precision Flight Simulator) w/Mode 2 Controller ... 6

Field Equipment ............................. 6

Optional Retracts............................. 6

Contents of Kit and Replacement Parts ............ 7

Warranty Period ............................. 8

Limited Warranty............................. 8

Damage Limits .............................. 8

Safety Precautions ........................... 8

Questions, Assistance, and Repairs .............. 9

Inspection or Repairs ......................... 9

Warranty Inspection and Repairs................. 9

Non-Warranty Repairs......................... 9

Safety, Precautions, and Warnings .............. 10

Section 1: Hinging the Flaps and Ailerons ........ 11

Section 2: Aileron Servo Installation............. 14

Section 3: Fixed Flap Linkage Installation......... 20

Section 4: Operation Flap Linkage Installation ..... 22

Section 5: Electric Motor Installation ............ 26

Section 6: Glow Engine Installation ............. 30

Section 7: Fixed Landing Gear Installation . . . . . . . . 39

Section 8: Retractable Landing Gear Installation.... 44

Section 9: Retract Valve and Hardware ........... 52

Section 10: Engine Nacelle Installation........... 54

Section 11: Wing Installation .................. 57

Section 12: Rudder and Servo Installation ........ 59

Section 13: Tail Section Installation ............. 64

Section 14: Receiver, Battery

and Scale Accessories .............. 68

Recommended Center of Gravity (CG) ........... 72

Control Throws ............................. 73

Range Test Your Radio ....................... 73

Retract Air line Routing Diagram................ 74

Pre-Flight ................................. 75

Engine Run-In Instructions .................... 75

Takeoff.................................... 76

Landing................................... 76

Engine Out ................................ 77

2007 Official AMA

National Model Aircraft Safety Code ............. 78

2

Using the Manual

This manual is divided into sections to help make assembly easier to understand, and to provide breaks between each
major section. In addition, check boxes have been placed next to each step to keep track of each step completed. Steps
with a single box (
repeating, such as for a right or left wing panel, two servos, etc. Remember to take your time and follow the directions.

) are performed once, while steps with two boxes ( ) indicate that the step will require

Required Tools and Adhesives

Tools

• Felt-tipped pen or pencil • Flat screwdriver

• Adjustable wrench • Drill

• Hobby knife • Masking tape

• Phillips screwdriver (large) • Phillips screwdriver (small)

• Ruler • Sandpaper

• Soldering iron • Solder

• Hex wrench: 3/32-inch, 2mm, 9/64, 3/16, (1.5mm included with kit)

• Drill bit: 1/16-inch (1.5mm), 5/64-inch (2mm), 7/64-inch (3mm), 9/64-inch (3.5mm),

5/32-inch (4mm), 7/32-inch (5.5mm), 1/4-inch (6mm)

Adhesives

• Formula 560 Canopy Glue (PAAPT56) • Pacer Z-42 Threadlock (PAAPT42)

• Thin CA (cyanoacrylate) Glue (PAAPT07) • CA Remover/Debonder (PAAPT16)

• 30-minute epoxy (HAN8002)

UltraCote Covering Colors

• Olive Drab HANU904 • Light Gray HANU882

• White HANU870 • Sky Blue HANU875

• Dark Yellow HANU889

Before Starting Assembly

Before beginning the assembly of the B-25 Mitchell, remove each part from its bag for inspection. Closely inspect
the fuselage, wing panels, rudders, and stabilizer for damage. If you find any damaged or missing parts, contact the
place of purchase.

If you find any wrinkles in the covering, use a heat gun or sealing iron to remove them. Use caution while working
around areas where the colors overlap to prevent separating the colors.

HAN101 – Sealing Iron

HAN141 – Sealing Iron

Sock

HAN100 – Heat Gun

HAN150 – Covering Glove

3

Radio and Power Systems Requirements

• JR Charge Switch (JRPA004)

• 2400mAh Ni-Cd 5 cell (JRPB4470)*

*The additional weight of this Sub C battery pack will help in achieving the correct CG balance of the B-25 model

Required Servo Extensions

7-Channel Radio Setup:
Channel Function Extension Notes

1 and 7 Throttle 18-inch (JSP98120) (2), 6-inch (JSP98110) (2)
2 Aileron 18-inch (JSP98120) (2), “Y” harness (JSP98020)
3 Elevator None
4 Rudder/Nose wheel “Y” harness (JSP98020) (2), 24-inch (JSP98040) Reverse servo required for

nose wheel
5 Retracts None
6 Flaps “Y” harness (JSP98020), 12-inch (JSP98030) One reverse servo required

9-Channel Radio Setup:
Channel Function Extension Notes

1 Throttle (right) 18-inch (JSP98120), 6-inch (JSP98110)
2 Aileron 18-inch (JSP98120) (2), “Y” harness (JSP98020)
3 Elevator None
4 Rudder “Y” harness (JSP98020), 24-inch (JSP98040)
5 Retracts None
6 Flap (right) 12-inch(JSP98030), 6-inch(JSP98110)
7 Flap (left) 12-inch(JSP98030), 6-inch(JSP98110)
8 Throttle (left) 18-inch (JSP98120), 6-inch (JSP98110)
9 Nose wheel 6-inch (JSP98110)

4

Recommended JR, JR SPORT and Spektrum Systems

• 10X

• XP9303

• XP7202

• DX7

• XP6102

• XS600

JR XP9303

Spektrum DX7

JR XP7202

Recommended Setup–Glow

• Evolution .36NT 2-Stroke Glow Engine with Muffler (EVOE0360) (2)

• 6-channel or more radio system

• 8 JR Digital Sport Hi-Torque DS821 Servos or JR SPORT High-Torque ST126MG Servos

• 2 JR 331 Micro Servos (JRPS331) (3 if adding optional retracts)

• 3/4" Spinner Nut (TRU7A140 1/4-28 Threads) (2)

• 10.5x4 3-Blade Propeller (EVOE100P) to 11 x 4 2-Blade Propeller (APC11040) (2)

Recommended Setup–Electric

• Power 46 BL outrunner motor (EFLM4046A) (2)

• 60 amp ESC (EFLM1060) (2)

• Thunder Power 4S 14.8V 3850mAh to 4200mAh Li-Po (2 required)

• 6-channel or more radio system

• 6 JR Digital Sport Hi-Torque DS821 Servos or JR SPORT High-Torque ST126MG Servos

• 2 JR 331 Micro Servos (JRPS331) (3 if adding optional retracts)

• 3/4" Spinner Nut (TRU7C516 5/16-24 Threads) (2)

• 13x8E Propeller (APC13080E) (2)

Spektrum is used with permission of

Bachmann Industries, Inc.

5

FS One (Precision Flight Simulator) w/Mode 2 Controller

With FS One® you get more than photorealistic fields, gorgeous
skies and realistic-looking aircraft. You get incredibly advanced
aerodynamic modeling that simulates every possible aspect
of real-world flight.

HANS2000

Field Equipment

• Propeller • Fuel

• Glow Plug Wrench (HAN2510) • Glow Plug Igniter w/Charger(HAN7101)

• Glow Plug (EVOGP1) • Manual Fuel Pump (HAN118)

Optional Retracts

Hangar 9 offers two versions of Robart retractable landing
gear for the B-25 Mitchell:

HANB25 (Includes the following parts)

• Robart tricycle retracts • Robostruts*

• Retract valve • Air Tubing

• Filler valve • “T” fittings

• Quick disconnects • Air Tank

*The Robostruts are factory cut to the correct length.

HANB25S (Includes the following parts)

• Robart tricycle retracts • Robostruts*

*The Robostruts are factory cut to the correct length.

In addition, you are required to supply:

• ROB164G Robart air pump to fill the air tank

Hardware needed to complete optional installation of Robart retracts

• 4-40 x 1-inch socket head bolts (12)

• 4-40 blind nuts (12)

• #4 washers (12)

• #10 washers for axle spacers (6)

• 2mm x 2-56 Ball Link (HAN3618) (2)

• Material to fabricate the mount for the retract valve.

6

Contents of Kit and Replacement Parts

Replacement Large Parts

A. HAN4452 Wings w/ Flaps & Ailerons B. HAN4451 Fuselage
C. HAN4453 Rudders (pr.) D. HAN4455 Left Nacelle
E. HAN4456 Right Nacelle F. HAN4454 Stabilizer & Elevator
G. HAN4461 Fuselage Bottom Hatch

B

D

A

Replacement Small Parts

1. HAN4463 Front Greenhouse Canopy

2. HAN4464 Main Cockpit Canopy

3. HAN4468 Dummy Radial Engine (ea)

4. HAN4458 Fixed Landing Gear w/o Wheels

5. HAN4466 Right Nacelle Top Cover

6. HAN4465 Left Nacelle Top Cover

7. HAN4459 Canopy Set and Gun Turrets

8. HAN4460 Guns & Radiators

Items not shown

G

E

C

F

1 2

7

8

5 6

9

7

HAN4462 Push Rod Set
HAN4467 Decal Sheet (Nose Art)
HAN4457 Cowl (ea.)

™

The following Hangar 9 Pro-Lite

wheels can

be used as replacements for the B-25:

8. HAN304 Nose wheel 2

9. HAN307 Main wheel 3

1

/2-inch (63mm)

1

/4-inch (83mm)

8

34

8

7

Warranty Period

Exclusive Warranty- Horizon Hobby, Inc., (Horizon) warranties that the Products purchased (the "Product") will be free

from defects in materials and workmanship at the date of purchase by the Purchaser.

Limited Warranty

(a) This warranty is limited to the original Purchaser ("Purchaser") and is not transferable. REPAIR OR REPLACEMENT
AS PROVIDED UNDER THIS WARRANTY IS THE EXCLUSIVE REMEDY OF THE PURCHASER. This warranty covers only

those Products purchased from an authorized Horizon dealer. Third party transactions are not covered by this warranty.
Proof of purchase is required for warranty claims. Further, Horizon reserves the right to change or modify this warranty
without notice and disclaims all other warranties, express or implied.

(b) Limitations- HORIZON MAKES NO WARRANTY OR REPRESENTATION, EXPRESS OR IMPLIED, ABOUT NON-

INFRINGEMENT, MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE OF THE PRODUCT. THE
PURCHASER ACKNOWLEDGES THAT THEY ALONE HAVE DETERMINED THAT THE PRODUCT WILL SUITABLY MEET
THE REQUIREMENTS OF THE PURCHASER’S INTENDED USE.

(c) Purchaser Remedy- Horizon's sole obligation hereunder shall be that Horizon will, at its option, (i) repair or (ii)
replace, any Product determined by Horizon to be defective. In the event of a defect, these are the Purchaser's exclusive
remedies. Horizon reserves the right to inspect any and all equipment involved in a warranty claim. Repair or replacement
decisions are at the sole discretion of Horizon. This warranty does not cover cosmetic damage or damage due to acts of
God, accident, misuse, abuse, negligence, commercial use, or modification of or to any part of the Product. This warranty
does not cover damage due to improper installation, operation, maintenance, or attempted repair by anyone other than
Horizon. Return of any goods by Purchaser must be approved in writing by Horizon before shipment.

Damage Limits

HORIZON SHALL NOT BE LIABLE FOR SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES, LOSS OF PROFITS OR

PRODUCTION OR COMMERCIAL LOSS IN ANY WAY CONNECTED WITH THE PRODUCT, WHETHER SUCH CLAIM
IS BASED IN CONTRACT, WARRANTY, NEGLIGENCE, OR STRICT LIABILITY. Further, in no event shall the liability of
Horizon exceed the individual price of the Product on which liability is asserted. As Horizon has no control over use,
setup, final assembly, modification or misuse, no liability shall be assumed nor accepted for any resulting damage or
injury. By the act of use, setup or assembly, the user accepts all resulting liability.

If you as the Purchaser or user are not prepared to accept the liability associated with the use of this Product, you are
advised to return this Product immediately in new and unused condition to the place of purchase.

Law: These Terms are governed by Illinois law (without regard to conflict of law principals).

Safety Precautions

This is a sophisticated hobby Product and not a toy. It must be operated with caution and common sense and requires
some basic mechanical ability. Failure to operate this Product in a safe and responsible manner could result in injury
or damage to the Product or other property. This Product is not intended for use by children without direct adult
supervision. The Product manual contains instructions for safety, operation and maintenance. It is essential to read
and follow all the instructions and warnings in the manual, prior to assembly, setup or use, in order to operate correctly
and avoid damage or injury.

8

Questions, Assistance, and Repairs

Your local hobby store and/or place of purchase cannot provide warranty support or repair. Once assembly, setup or
use of the Product has been started, you must contact Horizon directly. This will enable Horizon to better answer your
questions and service you in the event that you may need any assistance. For questions or assistance, please direct your
email to [e-mail], or call 877.504.0233 toll free to speak to a service technician.

Inspection or Repairs

If this Product needs to be inspected or repaired, please call for a Return Merchandise Authorization (RMA). Pack
the Product securely using a shipping carton. Please note that original boxes may be included, but are not designed
to withstand the rigors of shipping without additional protection. Ship via a carrier that provides tracking and insurance
for lost or damaged parcels, as Horizon is not responsible for merchandise until it arrives and is accepted
at our facility. A Service Repair Request is available at www.horizonhobby.com on the “Support” tab. If you do not
have internet access, please include a letter with your complete name, street address, email address and phone number
where you can be reached during business days, your RMA number, a list of the included items, method of payment
for any non-warranty expenses and a brief summary of the problem. Your original sales receipt must also be included
for warranty consideration. Be sure your name, address, and RMA number are clearly written on the outside of the
shipping carton.

Warranty Inspection and Repairs

To receive warranty service, you must include your original sales receipt verifying the proof-of-purchase
date. Provided warranty conditions have been met, your Product will be repaired or replaced free of charge. Repair or
replacement decisions are at the sole discretion of Horizon Hobby.

Non-Warranty Repairs

Should your repair not be covered by warranty the repair will be completed and payment will be
required without notification or estimate of the expense unless the expense exceeds 50% of the retail
purchase cost. By submitting the item for repair you are agreeing to payment of the repair without notification. Repair

estimates are available upon request. You must include this request with your repair. Non-warranty repair estimates will
be billed a minimum of ½ hour of labor. In addition you will be billed for return freight. Please advise us of your preferred
method of payment. Horizon accepts money orders and cashiers checks, as well as Visa, MasterCard, American Express,
and Discover cards. If you choose to pay by credit card, please include your credit card number and expiration date. Any
repair left unpaid or unclaimed after 90 days will be considered abandoned and will be disposed of accordingly. Please
note: non-warranty repair is only available on electronics and model engines.

Electronics and engines requiring inspection or repair should be shipped to the following address:

Horizon Service Center

4105 Fieldstone Road

Champaign, Illinois 61822

All other Products requiring warranty inspection or repair should be shipped to the following address:

Horizon Product Support

4105 Fieldstone Road

Champaign, Illinois 61822

Please call 877-504-0233 with any questions or concerns regarding this product or warranty.

9

Safety, Precautions, and Warnings

This model is controlled by a radio signal that is subject to interference from many sources outside your control. This
interference can cause momentary loss of control so it is advisable to always keep a safe distance in all directions around
your model, as this margin will help to avoid collisions or injury.

• Always operate your model in an open area away from cars, traffic, or people.

• Avoid operating your model in the street where injury or damage can occur.

• Never operate the model into the street or populated areas for any reason.

• Never operate your model with low transmitter batteries.

• Carefully follow the directions and warnings for this and any optional support equipment (chargers, rechargeable

battery packs, etc.) that you use.

• Keep all chemicals, small parts and anything electrical out of the reach of children.

• Moisture causes damage to electronics. Avoid water exposure to all equipment not specifically designed and protected

for this purpose.

10

Section 1: Hinging the Flaps and Ailerons

Required Parts

• Wing panel w/ailerons & flaps (right and left)

Required Tools and Adhesives

• Rotary tool • T-pins

• Drill bit: 1/16-inch (1.5mm) • Thin CA

• 30-minute epoxy • Mixing stick

• Mixing cup

  Step 1

Remove the flaps and aileron from the wing panel and set
aside the CA hinges.

  Step 3

Place a T-pin in the center of each of the eight hinges
removed in Step 1.

  Step 4

Slide the hinges back into the aileron. The T-pin will keep
the hinge centered evenly in the aileron and wing when
the aileron is installed.

  Step 2

Use a rotary tool and 1/16-inch (1.5mm) drill bit to drill
a 1/2-inch (12mm) deep hole in the center of each hinge
slot. This provides a tunnel allowing the glue used to
secure the hinges to fully penetrate the hinge.

11

Section 1: Hinging the Flaps and Ailerons

  Step 5

Slide the aileron and outer flap into position on the wing.
Make sure the inboard edge of the flap near the center of
the wing, and the outer tip of the aileron near the wing tip
do not bind against the wing. Also make sure the flap and
aileron do not bind against each other.

  Step 7

After the CA has fully cured, gently pull on the wing
and aileron to make sure the hinges are secure. If not,
re-glue the hinges.

  Step 8

To break in the hinges, you will need to flex the aileron up
and down a number of times.

  Step 6

Remove the T-pins from the hinge and push the aileron
tight against the wing. Flex the aileron and apply enough
thin CA to fully penetrate the hinge. Apply CA to both the
top and bottom of the hinge.

Important: Do not use accelerator when
hinging. The CA must be allowed to soak
into the hinge for the best possible bond
between the hinge and surrounding wood.

12

Section 1: Hinging the Flaps and Ailerons

  Step 9

Use medium grit sandpaper to sand the flap
torque rods. Use rubbing alcohol and a paper towel
to remove any debris from the torque rod. This will
aid in strengthening the bond between the flap torque
rod and flap.

  Step 11

Use medium grit sandpaper to sand the flap
torque rods. Use rubbing alcohol and a paper towel
to remove any debris from the torque rod. This will
aid in strengthening the bond between the flap torque
rod and flap.

  Step 10

Hinging the flaps follows the same procedure as the
ailerons, except you will need to apply 30-minute epoxy to
the torque rods that enter the flaps.

  Step 12

Hinging the flaps follows the same procedure as the
ailerons, except you will need to apply 30-minute epoxy to
the torque rods that enter the flaps.

 Step 13

Repeat Steps 1 though 12 for the remaining wing panel.

13

Section 2: Aileron Servo Installation

Required Parts

• Assembled wing panel (right and left)

• Servo w/hardware (2) • Control horn (2)

• Pushrod connector (2) • Nylon clevis (2)

• Servo mounting block (4)

• 6-inch (152mm) pushrod wire (2)

• 2-56 x 7/8-inch machine screw (6)

• #2 x 3/8-inch sheet metal screw (8)

• 1/4-inch (6mm) heat shrink tubing

• 18-inch (457mm) servo extension (2)

1

• 1

/8 x 1/4-inch (28mm x 6mm) dowel

1

• 1

/8 x 5/16-inch (28mm x 8mm) dowel (2)

Required Tools and Adhesives

• Drill • Thin CA

• Phillips screwdriver • Long servo arm

• 30-minute epoxy • Hobby knife

• Pencil • Felt-tipped pen

• Drill bit: 1/16-inch (1.5mm), 5/32-inch (2mm)

  Step 1

Remove the servo cover from the wing. Use a sharp hobby
knife to remove the covering from the opening in the cover
so the servo arm can extend outside the cover.

  Step 2

Position the aileron servo on the cover with the servo arm
centered in the opening. Use a pencil to mark the cover
where the flap servo is positioned.

  Step 3

Use 30-minute epoxy to glue the servo mounting
blocks to the servo cover. Allow the epoxy to fully
cure before proceeding.

14

Section 2: Aileron Servo Installation

  Step 4

Position the servo between the servo mounting
blocks. Make sure the servo is not resting on the
servo cover, which will transfer vibrations to the servo.
Use a felt-tipped pen to mark the locations for the servo
mounting screws.

  Step 5

Use a drill and 1/16-inch (1.5mm) drill bit to drill the four
holes for the servo mounting screws.

  Step 6

Apply a few drops of thin CA into each of the holes to
harden the surrounding wood to provide a stronger
surface for the screws to bite into.

  Step 7

Mount the servo to the blocks using the hardware
provided with the servo.

15

Section 2: Aileron Servo Installation

  Step 8

Secure an 18-inch (457mm) servo extension to the servo
lead for the aileron. Make sure to secure the servo lead
to the extension using string or a commercially available
connector to prevent them from becoming disconnected
inside the wing.

  Step 9

Tie the string that has been installed inside the wing
to the servo extension. Use the string to pull the servo
leads through the wing and to the opening of the wing
panel near the flap servo. You will pull the flap servo leads
and the throttle servo leads with this same pull string.

  Step 10

Use a drill and 1/16-inch (1.5mm) drill bit to drill four
holes, approximately 1/8-inch (3mm) from the corners of
the servo cover.

  Step 11

Use four #2 x 3/8-inch sheet metal screws to secure the

servo cover to the wing.

16

Align holes

with hinge line

Section 2: Aileron Servo Installation

  Step 12

Cut two 1/4-inch (4mm) long pieces from the heat
shrink tubing and slide it onto each of the clevises.
Thread a nylon clevis onto the 6-inch (152mm) aileron
pushrod wire.

  Step 13

Remove the backplate from a control horn. Connect the
clevis to the horn and position the horn so the pushrod
is parallel to the servo horn. Align the holes in the horn
with the hinge line. Use a felt-tipped pen to transfer the
locations for the mounting screws on the aileron.

17

Section 2: Aileron Servo Installation

  Step 14

Use a drill and 5/32-inch (2mm) drill bit to drill the three
mounting holes through the aileron.

  Step 15

Apply a few drops of thin CA into each hole to harden the
surrounding wood. You may need to run the drill bit back
through the holes after applying the CA.

  Step 16

Attach the control horn to the aileron using three
2-56 x 7/8-inch machine screws and the control
horn backplate.

18

Section 2: Aileron Servo Installation

  Step 17

Hold the aileron so it is aligned in the centered position.
With the servo centered, use a felt-tipped pen to mark
where the pushrod crosses the servo arm.

  Step 18

Bend the pushrod wire 90 degrees at the mark made in
the previous step. Use a pushrod connector to secure the
pushrod to the servo arm. Use side cutters to remove any
excess wire extending beyond the connector.

  Step 19

Use 30-minute epoxy to glue the 1
(28mm x 8mm) wing dowel in the wing. Press the
dowel into the wing and clean any excess epoxy from
the dowel and wing.

1

/8 x 5/16-inch

 Step 20

Repeat Steps 1 though 19 for the remaining wing panel.

 Step 21

Use 30-minute epoxy to glue the 1
(28mm x 6mm) wing dowel in the wing. Press the
dowel into the wing and clean any excess epoxy from
the dowel and wing.

1

/8 x 1/4-inch

19

Section 3: Fixed Flap Linkage Installation

Required Parts

• Assembled wing panel (right and left)

• Fixed flap stay (2) • Flap linkage (2)

• Pushrod connector (2) • Nylon clevis (4)

• 1/4-inch (4mm) heat shrink tubing

Required Tools and Adhesives

• 30-minute epoxy • Hobby knife

• Heat gun

Note: The following steps cover the
installation of fixed flaps on your
B-25 Mitchell. You can skip to

"Section 4: Operational Flap
Linkage Installtion" if you are

installing operational flaps.

  Step 1

Remove the covering from the wing slot to insert the fixed
flap stay in the wing.

  Step 2

Sand the flap stay using medium grit sandpaper. Use
rubbing alcohol and a paper towel to remove any dirt and
debris from the flap stay. This will help in strengthening
the bond between the flap stay and wing rib.

  Step 3

Use 30-minute epoxy to glue the flap stay in the wing.

20

  Step 4

Cut two 1/4-inch (4mm) long pieces from the heat shrink
tubing and slide it onto each of the clevises. Thread the
clevises onto the flap linkage.

Section 3: Fixed Flap Linkage Installation

  Step 5

Attach the clevises to the flap control horns.

  Step 6

Hold the flap so it is aligned in the centered position. Use
a felt-tipped pen to mark where the pushrod crosses the
flap stay.

  Step 7

Bend the pushrod wire 90 degrees at the mark made in the
previous step.

  Step 8

Use the pushrod connector to secure the linkage to the
flap stay. Adjust the position of the clevises to center the
flaps in the up position. Use a heat gun to shrink the heat
shrink tubing to secure the clevis closed.

 Step 9

Repeat Steps 1 though 8 for the remaining wing panel.

21

Section 4: Operation Flap Linkage Installation

Required Parts

• Assembled wing panel (right and left)

• Servo w/hardware (2) • Flap linkage (2)

• Pushrod connector (2) • Nylon clevis (4)

• 1/4-inch (4mm) heat shrink tubing

• Y-harness

or
12-inch (305mm) servo extenstion (2)

Required Tools and Adhesives

• Hobby knife • Phillips screwdriver

• Drill bit: 1/16-inch (1.5mm) • Thin CA

• Drill

  Step 1

Use a sharp hobby knife to remove the covering for the
flap servo from the wing.

  Step 2

Position the flap servo in the opening. Route the servo
lead out of the opening where the aileron extension is
located. The horn on the servo will be toward the leading
edge of the wing. Use a felt-tipped pen to mark the
locations for the servo mounting screws.

  Step 3

Use a drill and 1/16-inch (1.5mm) drill bit to drill the
locations for the servo mounting screws.

22

Section 4: Operation Flap Linkage Installation

  Step 4

Apply a few drops of thin CA to each of the holes drilled
in the previous step. This will help harden the wood,
making the screws more secure in their placement.

  Step 5

Secure the flap servo in the wing using the hardware
provided with the servo.

  Step 6

The string will now be attached to the flap servo lead and
to the aileron extension.

  Step 7

Remove the standard servo arm from your servo and
install the longer 180-degree servo arm included with
the servo. With the flap servo plugged into the receiver,
use the radio system to operate the flap servo. After
determining the up and down positions, set the flap servo
into the up position.

23

Section 4: Operation Flap Linkage Installation

  Step 8

Cut two 1/4-inch (4mm) long pieces from the heat shrink
tubing and slide it onto each of the clevises. Thread the
clevises onto the flap linkage.

  Step 9

Hold the flap so it is aligned in the centered position. Use
a felt-tipped pen to mark where the pushrod crosses the
servo arm.

  Step 10

Bend the pushrod wire 90 degrees at the mark made in the
previous step.

  Step 11

Leave the radio system on to prevent the servo from
changing position. Use a 5/64-inch (2mm) drill bit to
enlarge the outer hole in the servo arm. Attach the linkage
to the servo arm using a pushrod connector.

24

  Step 12

Adjust the position of the clevises so the flaps are aligned
with the trailing edge of the wing when the flap servo is in
the up position. Use the heat shrink tubing and heat gun
to make sure the clevises will not become disconnected
from the flap control horns. Be careful not to damage the
covering.

Section 4: Operation Flap Linkage Installation

 Step 13

Repeat Steps 1 though 10 for the remaining flap linkage.

25

Section 5: Electric Motor Installation

Required Parts

• Engine nacelle (right and left) • Speed control (2)

• Mounting template (right and left) •#8 washer (4)

• Dummy radial engine (2) • Cowl (2)

• Motor w/hardware (2)

•#2 x 3/8-inch sheet metal screw (8)

3

• 1

/4-inch (45mm) motor standoff (2)

• 8-32 x 3/4-inch socket head screw (8)

Required Tools and Adhesives

• Drill • Thin CA

• Phillips screwdriver • Long servo arm

• Card stock • Masking tape

• 30-minute epoxy • Hobby knife

• Rotary tool • Sanding drum

• Drill bit: 1/16-inch (1.5mm), 5/32-inch (4mm)

  Step 1

Tape the appropriate template to the front of the engine
nacelle. Use a drill and a 1/16-inch (1.5mm) drill bit to
drill the four locations for the motor standoffs.

  Step 2

Enlarge the holes for the motor standoff screws using a
drill and 5/32-inch (4mm) drill bit.

  Step 3

Use a drill and a 5/32-inch (4mm) drill bit to enlarge the

outer mounting holes in the X-mount for your motor.

26

Section 5: Electric Motor Installation

  Step 4

Attach the X-mount to the motor using the hardware

supplied with the motor.

Important: Use threadlock on
any metal-to-metal fasteners.

  Step 6

Attach the motor to the standoffs using four 8-32 x
3/4-inch socket head screws. Tighten all the screws
at this time.

Note: Use threadlock on all eight of the
8-32 screws required to mount the motor.

  Step 5

Attach the four 1
firewall to the engine nacelle using four 8-32 x 3/4-inch
socket head screws and four #8 washers. Leave the
screws slightly loose in case the standoffs need to be
moved slightly.

3

/4-inch (45mm) motor standoffs to the

  Step 7

Solder any necessary connector to the speed control.
Connect the leads between the motor and speed control.
Secure the speed controller to the motor standoffs using
double-sided tape and tie wraps. Route the power lead and
servo lead through the hole in the center of the firewall.

27

Section 5: Electric Motor Installation

  Step 8

Use hobby scissors and a rotary tool with a small sanding
drum to make a round opening in the dummy engine for
the motor shaft.

  Step 9

Use a sharp hobby knife to remove the material between
the dummy cylinder heads to allow cooling air to pass
through the dummy engine and over the motor.

  Step 10

Use 30-minute epoxy to glue the dummy engine inside
the cowling.

  Step 11

Tape four pieces of card stock to the engine nacelle. Align
the card stock so the ends align with the front edge of
the firewall. Align the sides of the card stock so they are
centered on the raised areas of the nacelle.

28

Section 5: Electric Motor Installation

  Step 12

Slide the cowling onto the nacelle and align the opening
in the dummy engine with the propeller adapter of the
motor. Temporarily tape the cowl into place.

  Step 13

Drill four locations for the mounting screws using a
1/16-inch (1.5mm) drill bit. Drill the holes centered
in the card stock and approximately 1/8-inch (3mm) back
from the end of the template to guarantee drilling into
the hardwoood positioned behind the raised areas of
the nacelle.

  Step 14

Apply a few drops of thin CA to each of the holes drilled
in the previous step. This will help harden the wood,
making the screws more secure in their placement.

  Step 15

Secure the cowling to the engine nacelle using four

#2 x 1/2-inch sheet metal screws.

 Step 16

Repeat Steps 1 through 14 for the remaining
motor installation.

29

Section 6: Glow Engine Installation

Required Parts

• Engine nacelle (right and left) • Engine (2)

•#8 washer (4) • Cowl (2)

• Fuel tank (2) • 8-32 blind nut (2)

• 4-40 locknut (8) • #4 washer (8)

• Servo w/hardware (2) • EZ link (2)

• 2mm washer (2) • C-clip (2)

• 2mm setscrew (2)

• Dummy radial engine (2)

• Fuel Dot Filler (HAN115) (2)

• Mounting template (right and left)

• 4-40 x 1-inch socket head bolt (8)

• Pushrod tube, 6-inch (152mm) (2)

•#2 x 3/8-inch sheet metal screw (8)

• 8-32 x 1

• Throttle pushrod, 9

1

/4-inch socket head screw (8)

1

/2-inch (241mm) (2)

Required Tools and Adhesives

• Drill • Medium CA

• Phillips screwdriver • Long servo arm

• Card stock • Masking tape

• 30-minute epoxy • Hobby knife

• Rotary tool • Sanding drum

• Threadlock

• Ball driver: 9/64-inch

• Drill bit: 1/16-inch (1.5mm), 5/32-inch (4mm),

7/32-inch (5.5mm)

  Step 1

Tape the appropriate template to the front of the engine
nacelle. Use a drill and a 1/16-inch (1.5mm) drill bit to
drill the four locations for the motor mount blind nuts.
and also drill the hole for the throttle pushrod. The throttle
pushrod hole is included on the engine template.

  Step 2

Enlarge the holes for the motor standoff screws using a
drill and 7/32-inch (4mm) drill bit.

30

Section 6: Glow Engine Installation

  Step 3

Use a short 8-32 socket head bolt and 9-64-inch
ball driver to draw the 8-32 blind nuts into the back side
of the firewall.

  Step 4

Use a drill and 5/32-inch (4mm) drill bit to enlarge the
hole for the throttle pushrod.

  Step 5

Use medium CA to glue the pushrod housing into the
firewall.

  Step 6

Use side cutters to cut the pushrod tube 1/4-inch (4mm)
behind the forward edge of the opening for the throttle
servo.

31

Section 6: Glow Engine Installation

  Step 7

Attach the engine to the engine mount using four
4-40 x 1-inch socket head screws, four #4 washers
and four 4-40 locknuts. The included engine mount is
drilled for the Evolution 36NT.

Note: The distance from the rear of the
mount to the front edge of the drive washer
will be 4
engine other than the Evolution engine
may required drilling new holes in the
mount for the engine mounting screws.

3

/16-inch (107mm). Using an

  Step 9

Slide the pushrod into the pushrod tube. Secure the
engine mount to the firewall using four 8-32 x 1

1

/4-inch

socket head bolts and four #8 washers. Bend the pushrod

wire slightly so it moves freely inside the pushrod tube
and will clear the muffler.

  Step 10

Use a pin drill and 5/64-inch (2mm) drill bit to enlarge the
hole in the throttle servo arm.

  Step 8

Pass the Z-bend of the throttle pushrod into the carburetor

arm.

32

Section 6: Glow Engine Installation

  Step 11

Slide the pushrod connector into the hole.

  Step 12

Secure the connector using a 2mm washer and C-clip.

  Step 14

Position the servo in the opening with the servo arm
facing the rear of the necelle. Mark the locations for the
servo mounting screws using a felt-tipped pen.

  Step 15

Use a drill and 1/16-inch (1.5mm) drill bit to drill the
locations for the servo mounting screws.

  Step 13

Remove the excess arms from the servo horn. Center the
throttle servo and attach the arm to the servo.

33

Section 6: Glow Engine Installation

  Step 16

Apply a few drops of thin CA into each hole to harden the
surrounding wood. You may need to run the drill bit back
through the holes after applying the CA.

  Step 17

Mount the servo in the engine nacelle as shown.

  Step 18

Electronically move the throttle servo to low, and
physically close the carburetor. Secure the position of
the wire using a 2mm setscrew and the included 1.5mm
hex wrench.

Note: Use threadlock on the setscrew
to prevent it from vibrating loose.

  Step 19

Use side cutters to trim the pushrod wire so only 1/2-inch
(12mm) extends beyond the rear of the pushrod connector.

34

Section 6: Glow Engine Installation

  Step 20

Attach the muffler to the engine following the instructions
provided with the engine.

  Step 21

Carefully inspect the fuel tank to determine which tube is
attached to the clunk and which is attached to the vent.
The vent will face toward the top of the tank.

  Step 22

Insert the tank into the fuselage, guiding the tubes though
the opening in the center of the firewall.

  Step 23

Secure the tank using the 1/4 x 1/4-inch stick provided
with the model. Cut the stick in half so you have a piece
for both fuel tanks.

35

Section 6: Glow Engine Installation

  Step 24

We used a fuel dot on the line to the needle valve that will
mount to the cowling, making fueling the engine much
easier when the cowl has been installed. When using a

fuel dot you will need to splice a "T" fitting between the

tank and the carburetor as shown.

  Step 25

Connect the lines from the tank to the engine.

  Step 26

Use hobby scissors and a rotary tool with a small sanding
drum to make a round opening in the dummy engine for
the motor shaft.

  Step 27

Use a sharp hobby knife to remove the material
between the dummy cylinder heads to allow cooling
air to pass through the dummy engine and over the
motor. Use 30-minute epoxy to glue the dummy engine
inside the cowling.

36

Note: Do not remove the area between all
of the dummy cylinder heads. You need to
only remove the area in front of and next
to the glow engine. This will help maintain
airflow over the engine cylinder head and
help to promote proper engine cooling.

Section 6: Glow Engine Installation

  Step 28

Tape four pieces of card stock to the engine nacelle. Align
the card stock so the ends align with the front edge of the
firewall. Align the length so it is aligned with the raised
areas of the nacelle.

  Step 29

  Step 30

Drill four locations for the mounting screws using a
1/16-inch (1.5mm) drill bit. Drill the holes centered
in the card stock and roughly 1/8-inch (3mm) back
from the end of the template to guarantee drilling into
the hardwoood positioned behind the raised areas of
the nacelle.

Slide the cowling onto the nacelle and align the
opening in the dummy engine with the propeller adapter
of the engine.

  Step 31

Apply a few drops of thin CA to each of the holes drilled
in the previous step. This will help harden the wood,
making the screws more secure in their placement.

37

Section 6: Glow Engine Installation

  Step 32

Secure the cowling to the engine nacelle using four

#2 x 1/2-inch sheet metal screws.

  Step 33

Cut an opening in the bottom of the cowling to the
dimensions shown to allow for cooling air to pass through
the cowl and over the engine.

  Step 34

Cut the necessary openings in the cowling for the muffler,
glow plug and fuel dot. Attach the propeller using a scale
propeller nut.

 Step 35

Repeat Steps 1 through 34 for the remaining engine
installation.

38

Section 7: Fixed Landing Gear Installation

Required Parts

• Assembled engine nacelle (right and left)

• Main landing gear (right and left)

• Steering arm • 5/32 wheel collar (7)

• 3mm setscrew (8) • Nose gear mount

• 3mm washer (8) • 3mm nut (4)

• Servo • Pull-pull cable

• Crimp (4) • Nylon clevis (2)

• Tapered nose gear block • Nose gear

• Rigging coupler, Z-bend (2)

• Rigging coupler, threaded (2)

• Nose wheel, 2

1

/2-inch (63mm)

• 3mm x 25mm machine screw (4)

• #4 x 1-inch sheet metal screw (8)

• Main wheel, 3

1

/4-inch (82mm) (2)

• #2 x 3/8-inch sheet metal screw (8)

Required Tools and Adhesives

• Flat file • Threadlock

• Drill • Felt-tipped pen

• Crimping pliers • Side cutters

• Hex wrench: 1.5mm (included)

• Drill bit: 1/16-inch (1.5mm), 5/64-inch (2mm),

7/64-inch (3mm)

  Step 2

Attach the 5/32-inch wheel collar to the landing gear
using a 3mm setscrew and the included 1.5mm hex
wrench. Use threadlock on the setscrew to prevent it from
vibrating loose.

  Step 3

Slide the wheel onto the gear and secure it with a final
wheel collar and setscrew.

  Step 1

Use a file to create a flat area on the main and nose gear
wires for the wheel collar setscrews. This helps in keeping
them secure on the landing gear.

Important: Use threadlock on
any metal-to-metal fasteners.

39

Section 7: Fixed Landing Gear Installation

  Step 4

Slide the main gear into the engine nacelle.

Note: Wheel not shown for clarity.

  Step 5

Use a drill and 5/64-inch (2mm) drill bit to drill four
holes through the mounting rails and into the gear
block. these holes are to be drilled 1/2-inch (13mm) and

1

then 1

/2-inch (38mm) from the front of the rear bulkhead.
The holes are to be centered on the rails. By doing this
you can later use the same holes to install the optional
retracts.

  Step 6

Enlarge the holes in the gear rails ONLY using a 7/64-inch
(3mm) drill bit.

  Step 7

Secure the main gear in the engine nacelle using four

#4 x 1-inch sheet metal screws.

40

 Step 8

Repeat Steps 1 through 7 to install the remaining main
gear in the engine nacelle.

Section 7: Fixed Landing Gear Installation

 Step 9

Slide the steering arm onto the nose gear wire. Next,
slide the mount on the wire, then a wheel collar. The
steering arm and wheel collar have setscrews that will
tighten onto the flat areas that have been pre-ground on
the nose gear wire.

Note: Make sure to use threadlock on the
setscrews for the steering arm and wheel collar.

 Step 10

 Step 11

Prepare four 3mm x 25mm machine screws by sliding a
3mm washer on each screw. Slide the screws through the
nose gear mount, then slide the tapered block onto the
screws. The wider section of the block will be away from
the steering arm. This tapered block creates the forward
105-degree rake of the nose gear.

 Step 12

Position the nose gear assembly in the fuselage and use
four 3mm washers and 3mm nuts to secure the nose gear
in the fuselage.

Install the rigging coupler in the steering arm as shown.

41

Section 7: Fixed Landing Gear Installation

Note: Use threadlock on all four of
the 3mm nuts to prevent vibrations
from loosening them.

 Step 13

Remove the standard servo arm and attach a large
180-degree standard arm on the servo. Position the
servo in the opening with the servo arm facing the rear
of the fuselage. Mark the locations for the servo mounting
screws using a felt-tipped pen.

 Step 15

Apply a few drops of thin CA into each hole to harden the
surrounding wood. You may need to run the drill bit back
through the holes after applying the CA.

 Step 16

Use the servo hardware to secure the steering servo
in the fuselage.

 Step 14

Use a drill and 1/16-inch (1.5mm) drill bit to drill the
locations for the servo mounting screws.

42

Section 7: Fixed Landing Gear Installation

 Step 17

Connect the pull-pull cable to the steering arm using
two crimps. Pass the cable through a crimp, through
the fasteners then back through the crimp. Use crimping
pliers to secure the crimps on the wire.

 Step 18

Center the nose gear and steering servo. Thread a clevis
on the threaded rigging couplers and attach them to the
steering servo arm. Make sure to cut a 1/4-inch (4mm)
piece of heat shrink tubing for each of the clevises and
slide them into position. Mark where the cable crosses the
hole in the fastener.

 Step 19

Repeat the crimping process, aligning the marks made
on the cable with the hole in the fastener. Cut any excess
cable using side cutters.

 Step 20

Place the doors in position and drill a 1/16-inch
(1.5mm) hole 1/8-inch (3mm) from the corners of the
steering servo and nose gear doors. Remove doors and
apply a few drops of thin CA into each hole of the doors
and the mounting tabs in the fuselage to harden the
surrounding wood.

 Step 21

Secure the doors over the steering servo and nose gear

with eight #2 x 3/8-inch sheet metal screws at each corner

of the doors.

43

Section 8: Retractable Landing Gear Installation

The following instructions will show you the installation of
the optional Robart retractable landing gear.

Hangar 9 offers two types of optional of Robart retractable
landing gear for the B-25 Mitchell.

HANB25 Includes the following parts:

• Robart tricycle retracts • Robostruts*

• Retract valve • Air Tubing

• Filler valve • “T” fittings

• Quick disconnects • Air Tank

*The Robostruts are factory cut to the correct length.

HANB25S Includes the following parts:

• Robart tricycle retracts • Robostruts*

*The Robostruts are factory cut to the correct length.

In addition, you are required to supply:

• ROB164G Robart air pump to fill the air tank

Hardware needed to complete optional
installation of Robart retracts

• 4-40 x 1-inch socket head bolts (12)

• 4-40 blind nuts (12)

• #4 washers (12)

• #10 washers for axle spacers (6)

• Material to fabricate the mount for the retract valve.

• 2-56 ball end (2)

 Step 2

Set the nose gear unit onto the mounting rails with the
retract placed up against the front firewall and mark the
mounting hole locations.

 Step 3

Remove the retract unit from the mounting rails and drill a
9/64-inch (4mm) hole on each of the marks.

Nose Gear Installation

 Step 1

Drill two 1/8-inch (3mm) holes in the rear bulkhead in the
nose gear wheel well to accept the air lines.

44

Section 8: Retractable Landing Gear Installation

 Step 4

From the back side of the mounting rails, insert the four
4-40 blind nuts and use a 4-40 bolt with a washer to draw
each blind nut into each one of the four holes you just
drilled.

 Step 5

 Step 6

Install 16 inches (406mm) of each color of air line onto
each of the air cylinder inlets on the landing gear. Feed the
two air lines through the two 1/8-inch (3mm) holes and
into the radio compartment. These air lines will be hooked
up later using the Robart air line diagram which we have
included on page 73 of this manual)

Install the recommended ball link studs onto the nose
wheel steering arms. The pull-pull cables will be hooked
up to these ball links in a later step.

Note: Be sure and use threadlock
on all metal-to-metal fasteners.

45

Section 8: Retractable Landing Gear Installation

 Step 7

Set the nose gear retract onto the mounting rails. Place

a # 4 washer onto each of the four 4-40 x 1-inch socket

head bolts, then securely fasten the retract to the mounting
rails with these four 4-40 x 1-inch bolts

 Step 9

Cut two 12-inch (305mm) lengths of pull-pull wire for
the steering. Connect the pull-pull cable to the steering
arm using two crimps. Pass the cable through a crimp,
through the fasteners then back through the crimp. Use

 Step 8

crimping pliers to secure the crimps on the wire.

Install the nose wheel onto a wheel axle and then install

two #10 washers onto the axle before inserting the wheel

and axle into the strut. The washers act as spacers to keep
the wheel from rubbing against the strut leg. Temporarily
tighten the setscrew and then cut off the excess axle using
a rotary tool and cutoff wheel. File a flat area on the axle
for the wheel strut setscrew and then install the wheel and
axle to the nose wheel strut. We used a couple of washers
between the wheel and the strut to keep the wheel from
rubbing on the strut.

Important: Use threadlock on
any metal-to-metal fasteners.

46

Section 8: Retractable Landing Gear Installation

 Step 10

Remove the standard servo arm and attach a large
180-degree standard arm on the servo. Position the
servo in the opening with the servo arm facing the rear
of the fuselage. Mark the locations for the servo mounting
screws using a felt-tipped pen.

 Step 11

Use a drill and 1/16-inch (1.5mm) drill bit to drill the
locations for the servo mounting screws.

 Step 12

Apply a few drops of thin CA into each hole to harden the
surrounding wood. You may need to run the drill bit back
through the holes after applying the CA.

 Step 13

Use the servo hardware that came with your servo to
secure the steering servo in the fuselage.

47

Section 8: Retractable Landing Gear Installation

 Step 14

Center the nose gear and steering servo. Thread a clevis
on the threaded rigging couplers and attach them to the
steering servo arm. Make sure to cut a 1/4-inch (4mm)
piece of heat shrink tubing for each of the clevises and
slide them into position. Mark where the cable crosses the
hole in the fastener.

 Step 15

Repeat the crimping process, aligning the marks made
on the cable with the hole in the fastener. Cut any excess
cable using side cutters.

 Step 16

Use a rotary tool and sanding drum to remove the area
of the nose gear cover to allow the nose wheel strut and
wheel to pass through.

Note: Use the same color air line for
up and then use the same other color
for down on each of the three retract
units. This will allow you to follow the
included air line diagram from Robart.

Note: Use threadlock on all screws to keep
them from coming loose during flight.

48

Section 8: Retractable Landing Gear Installation

 Step 17

We installed a rubber band to help hold the pull/pull
cables clear of the nose wheel and strut when it is
retracted/extended. Make a small plywood bracket with a
small opening in the end for the rubber band and glue the
bracket to the floor of the retract wheel well.

Main Gear Installation

  Step 19

Set the main gear onto the mounting rails and mark the
mounting hole locations.

  Step 20

Remove the retract unit from the mounting rails and drill a
9/64-inch (4mm) hole on each of the marks.

  Step 18

The nacelles have an outline on them showing the area
that needs to be removed to allow the struts to retract up
into the nacelle. Use a rotary tool and a sanding drum to
remove this area to allow the retract strut and wheel to
pass through.

49

Section 8: Retractable Landing Gear Installation

  Step 21

From the back side of the mounting rails, insert the
four 4-40 blind nuts and use a 4-40 bolt with a washer
to draw each blind nut into each one of the four holes
just drilled.

  Step 22

  Step 23

Set the main gear retract onto the mounting rails. Place

a # 4 washer onto each of the four 4-40 x 1-inch socket

head bolts, then securely fasten the retract to the mounting
rails with these four 4-40 x 1-inch bolts.

Install 20-inch (508mm) of each color of air line onto
each air cylinder inlet on the main landing gear. These air
lines will be pulled later through the same holes in the
wing that the throttle servo leads are pulled through. Be
certain to follow the included Robart air line diagram for
the correct hook-up of the colored air lines.

50

Section 8: Retractable Landing Gear Installation

  Step 24

Route the air lines from the retract unit through the nacelle
loosely. If you are installing the retracts and the wing
extensions are already in place, then you will need to use
a string and a weight to fish the air lines through the wing.
Both sets of these air lines will be hooked up later using
the Robart air installation diagram which we have included
on page 73 of this manual)

  Step 25

Install the main wheel onto a wheel axle and then install

two #10 washers onto the axle before inserting the wheel

and axle into the strut. The washers act as spacers to keep
the wheel from rubbing against the strut leg. Temporarily
tighten the setscrew and then cut off the excess axle using
a rotary tool and cutoff wheel. File a flat area on the axle
for the wheel strut setscrew and then install the wheel and
axle to the main wheel strut.

 Step 26

Repeat Steps 17 through 25 for the remaining main gear.

Note: Use threadlock on all screws to keep
them from coming loose during flight.

51

Section 9: Retract Valve and Hardware

All pushrod hardware and mounting plates are supplied
by the modeler.

 Step 1

You will need to fabricate a plywood plate to mount the
servo and the retract valve on. We made our mount from
lightweight plywood and a small piece of triangle stock.

 Step 2

We use a plastic 2-56 clevis to attach a 2-56 pushrod to

the retract valve and then make a “Z” bend on the other

end of the pushrod where it attaches to the servo arm. The
pushrod should be placed on the servo arm a distance
of approximately 1/2-inch (13mm) out from center of the
servo arm.

Note: Use travel volume on your radio
to allow a maximum 1/4-inch (6mm)
of travel on the pushrod. Be sure to
not over-throw the pushrod.

 Step 3

Mount the air fill valve on the fuselage so that you
have easy access to make the connection. The filler
valve will be less noticeable if mounted towards the
bottom of the fuselage. We chose to mount the valve
just forward of the leading edge of the wing next to the
steering servo access hatch.

52

Section 9: Retract Valve and Hardware

 Step 4

Install the air tank in the pre-cut position below the
radio tray. Follow the installation diagram instructions
from Robart to hook up the remaining air lines. We have
included enough extra air tubing with the optional air
kit to allow for ease of connection. Use approximately 6
inches of air line between all “T’ fittings. Add a few drops
of medium CA at the arrow to secure the tank in place.

 Step 5

You will need to make a decision at this time about
transporting the model. If you plan on taking the two
wings halves apart for transport, then you will need to
purchase two additional quick disconnects (1 pkg.) and
place one quick disconnect in each of the main retract
lines just before the “T” fittings used to connect the
main retract lines together. If you will be leaving the
wing together, then you will only need to install the two
included quick disconnects inline so the wing can be
removed for transport.

 Step 6

Pump the retracts up to approximately 100 PSI so you
can test how long the gear will hold air. Both the up and
down positions must not leak, but obviously the most
critical is when the gear are retracted for flight. The gear
should maintain pressure and only lose a few PSI (less
than 10 PSI) in 30 minutes. If the retracts will not hold air
this long, then please refer to the Robart troubleshooting
instructions on our web-site at the following URL:
http://www.hangar-9.com/Content/RT.pdf

53

Section 10: Engine Nacelle Installation

Required Parts

• Assembled wing panel (right and left)

• Assembled engine nacelle (right and left)

• 8-32 blind nut (4) • #8 washer (4)

• Nacelle support plate (2)

• Nacelle cover (right and left)

• 8-32 x 1-inch socket head screw (4)

1

• 1

/8 x 1/4-inch (28mm x 4mm) dowel (4)

Required Tools and Adhesives

• 30-minute epoxy • Hobby knife

• Masking tape

• Ball driver: 9/64-inch

  Step 1

Use a short 8-32 socket head bolt and 9/64-inch ball
driver to draw the two blind nuts up into the engine
nacelle mounting plate.

  Step 2

Place the nacelle support plate over the holes in the
trailing edge of the wing and trace the outline of the plate
onto the wing.

  Step 3

Use a sharp hobby knife to remove the covering where the
plate will be secured to the wing.

54

Section 10: Engine Nacelle Installation

  Step 4

Use 30-minute epoxy to glue the plate on the wing.

  Step 5

Use 30-minute epoxy to glue the two 1
(28mm x 4mm) dowels into the hole in the leading edge
of the wing for the engine nacelle.

1

/8 x 1/4-inch

  Step 6

Secure a 12-inch (305mm) servo extension to the throttle
(or speed control) lead. Tie the string around the end of
the extension as shown.

Note: If you have installed retracts,
you will need to tie the string to the
air lines as well in this step.

  Step 7

Carefully pull the servo extensions through the wing using
the string. The engine nacelle will need to be close to
the wing for the extension from the throttle servo (speed
control) to reach the opening in the wing. Once the
extensions have been pulled through the wing, use tape to
keep them from falling back into the wing.

55

Section 10: Engine Nacelle Installation

  Step 8

Attach the engine nacelle to the wing using two 8-32 x

1-inch socket head bolts and two #8 washers.

Note: Use threadlock on all screws to keep
them from coming loose during flight.

  Step 9

Position the nacelle top cover on the wing, aligning it with
the front and rear of the engine nacelle. Trace the outline
of the nacelle top cover on the wing with a felt-tipped pen.

  Step 10

Use a sharp hobby knife to remove a 1/8-inch (3mm) wide
strip to the inside of the line drawn in the previous step.

  Step 11

Use 30-minute epoxy to glue the nacelle top cover to
the wing. Use tape to hold the nacelle cover while the
epoxy cures.

56

  Step 12

Repeat Steps 1 through 11 to install the remaining engine
nacelle and nacelle top cover on the wing.

Section 11: Wing Installation

Required Parts

• Assembled wing panel (right and left)

• Wing tube •Wing bolt plate

• 1/4-inch washer (2)

• Battery tray (electric only)

• Hook and loop strap (electrtic only)

• 1/4-20 x 1

Required Tools and Adhesives

• Felt-tipped pen •Drill

• Ball driver: 3/16-inch

• Drill bit: 1/4-inch (6mm)

1

/2-inch socket head bolt (2)

 Step 1

Slide the wing tube into one of the wing panels.

 Step 3

Hold the wing bolt plate centered on the wing center
section. Use a felt-tipped pen to mark the location for one
of the holes in the plate.

 Step 4

Use a 1/4-inch (6mm) drill bit to make a hole in the plate.
Position the plate back on the wing.

 Step 2

Slide the remaining panel onto the wing tube. The panels
should fit tight against each other.

57

Section 11: Wing Installation

 Step 5

Use a wing bolt to keep the plate aligned at the first hole
and mark the location for the second hole on the plate.

 Step 6

Attach the wing using the wing bolt plate and two 1/4-20

1

x 1

/2-inch socket head bolts and two 1/4-inch washers.

Use a 3/16-inch ball driver to tighten the wing bolts.

Note: The Step 7 is for the EP version
only. Skip to Step 8 when building
the glow powered version.

 Step 7

When building an EP version of your B-25, attach the
batteries to the battery tray with hook and loop straps. The
tray keys into the former at the front, and is secured at the
rear using the wing bolts, with the wing bolt plate between
the wing and plate.

 Step 8

Fasten the belly hatch in position.

58

Section 12: Rudder and Servo Installation

Required Parts

• Stabilizer • Nylon clevis (2)

• Pushrod connector (2) • Control horn (2)

• Servo w/hardware (2)

• Rudder (right and left)

• Rudder linkage, 2-inch (51mm) (2)

• 2-56 x 7/8-inch machine screw (6)

• #2 x 3/8-inch sheet metal screw (8)

Required Tools and Adhesives

• Drill • Thin CA

• Phillips screwdriver • Long servo arm

• Hobby knife • Felt-tipped pen

• Pliers

• Drill bit: 1/16-inch (1.5mm), 5/32-inch (2mm)

  Step 1

Mounting the rudder servo follows the same procedure
as mounting the aileron servo (Section 2: Aileron Servo
Installation, Steps 1 through 7.) Use a 180 degree servo
arm and remove the excess arm using side cutters. Simply
follow those steps to mount the rudder servo to the rudder
servo cover.

  Step 3

Use a drill and 1/16-inch (1.5mm) drill bit to drill four
holes, approximately 1/8-inch (3mm) from the corners of
the servo cover.

  Step 4

Apply a few drops of thin CA to each of the holes to
harden the surrounding wood.

  Step 2

Route the servo lead to the nearest hole in the center of
the stabilizer using the installed string. Position the cover
so the servo arm is toward the tip of the stabilizer.

59

90-degrees

Section 12: Rudder and Servo Installation

  Step 5

Mount the servo cover using four #2 x 3/8-inch sheet

metal screws.

  Step 6

Use a sharp hobby knife to remove the covering from the
fin where the tab from the stabilizer will be inserted.

  Step 7

Use 30-minute epoxy to attach the fin to the stabilizer.

Note: Make sure the vertical fins remain
in alignment while the epoxy cures.

  Step 8

Remove the elevators and rudders from the stabilizer and
fins and set aside the CA hinges.

60

Section 12: Rudder and Servo Installation

  Step 9

Use a rotary tool and 1/16-inch (1.5mm) drill bit to drill
a 1/2-inch (12mm) deep hole in the center of each hinge
slot for the rudders and fins. This provides a tunnel
allowing the glue used to secure the hinges to fully
penetrate the hinge.

Note: Drill the holes in the hinge slots for the
elevators and stabilizer at this time as well.

  Step 10

  Step 12

Slide the rudder into position on the fin. Make sure the
rudder can move without binding against the fin at the top
and bottom.

  Step 13

Remove the T-pins from the hinge and push the rudder
tight against the fin. Flex the rudder and apply enough
thin CA to fully penetrate the hinge. Apply CA to both
sides of the hinge.

Place a T-pin in the center of each of the twelve hinges.

  Step 11

Slide the hinges back into the rudder. The T-pin will keep
the hinge centered evenly in the rudder and fin when the
rudder is installed.

Important: Do not use accelerator when
hinging. The CA must be allowed to soak
into the hinge for the best possible bond
between the hinge and surrounding wood.

61

Section 12: Rudder and Servo Installation

  Step 14

After the CA has fully cured, gently pull on the rudder
and fin to make sure the hinges are secure. If not, re-glue
the hinges.

  Step 15

To break in the hinges, you will need to flex the rudder
back and forth a number of times.

  Step 16

Use medium grit sandpaper to sand the evevator torque
rods. Use rubbing alcohol and a paper towel to remove
any dirt and debris from the torque rod. This will aid in
strengthening the bond between the elevator, torque rod
and epoxy.

  Step 17

Hinging the elevator follows the same procedure as the
rudder, except you will need to apply 30-minute epoxy to
the torque rods that enter the elevator.

 Step 18

Repeat Steps 1 through 17 for the remaining rudder
and elevator.

62

Section 12: Rudder and Servo Installation

  Step 19

Remove the backplate from a control horn. Thread a clevis
onto the 2-inch (51mm) rudder pushrod and attach the
clevis to the control horn. Make sure to cut a 1/4-inch
(4mm) piece of tubing to slide onto the clevis before
attaching it to the control horn.

  Step 21

Drill the three holes for the control horn mounting screw
and harden the surrounding wood with thin CA. Mount the
control horn using three 2-56 x 7/8-inch machine screws
and the control horn backplate. Mark the pushrod where
it crosses the outer hole of the rudder servo arm using a
felt-tipped pen.

  Step 20

Position the control horn on the fin so it won't interfere
with the elevator, and so it is in alignment with the rudder
servo arm. Mark the location for the three mounting
screws on the rudder.

  Step 22

Bend the pushrod 90 degrees at the mark and secure it
to the rudder servo arm. You will need to cut the pushrod
wire using side cutters so it will not interfere with the
rudder when operated.

  Step 23

Repeat Steps 19 through 21 to install the remaining
rudder and rudder servo.

63

Section 13: Tail Section Installation

Required Parts

• Tail assembly • Pushrod connector

• Clevis1 • Y-harness

• Servo w/hardware • #8 washer

• 8-32 blind nut

• 8-32 x 1-inch socket head bolt

• 24-inch (610mm) servo extension

1

• 1

/8 x 1/4-inch (28mm x 4mm) dowel

• Elevator pushrod wire, 36-inch (915mm)

Required Tools and Adhesives

• Drill • Thin CA

• 30-minute epoxy

• Hex driver: 9/64-inch

• Drill bit: 1/16-inch (1.5mm), 5/32-inch (2mm)

 Step 1

Use 30-minute epoxy to glue the 1
(28mm x 4mm) dowel into the hole in the leading
edge of the stabilizer.

1

/8 x 1/4-inch

 Step 2

Use a short 8-32 socket head bolt, 9/64-inch hex
driver and washer to draw the blind nut into the
fuselage as shown.

 Step 3

Connect the Y-harness and 24-inch (610mm) servo
extension to the rudder servos and pass them into the
radio compartment. Make sure to secure all connections
so they will not become unplugged inside the fuselage.
Cut a 1/4-inch (4mm) piece of heat shrink tubing and
slide it onto a clevis. Thread the clevis onto the elevator
pushrod wire and attach the clevis to the elevator control
horn. The pushrod then goes into the pushrod tube pre­installed in the fuselage.

64

Section 13: Tail Section Installation

 Step 4

Secure the stabilizer using a 9/64-inch hex driver,

8-32 x 1-inch socket head screw and #8 washer.

Note: You must use threadlock on the bolt
holding the stabilizer to the fuselage. It must
be secure so it will not vibrate loose in flight.

Important: Steps 5 through 7 cover how to
use epoxy to glue the stabilizer to the fuselage.
Using epoxy to glue the stabilizer is optional
but recommended if you will not have a need
to remove the stabilizer for transportation.

 Step 6

Use a hobby knife with a new #11 blade to remove a
3/8-inch (10mm) wide section of covering inside the
lines drawn in the previous step. Use care not to cut
into the underlying wood of the stabilizer.

Note: You can also use a soldering iron or
hot knife to help in preventing cutting into the
underlying wood and weakening the stabilizer.

 Step 7

Remove the covering from the stabilizer saddle on
the fuselage.

 Step 5

Use a felt-tipped pen to trace the outline of the fuselage
onto the stabilizer.

65

Section 13: Tail Section Installation

 Step 8

Mix up 1/2-ounce (15Ml) of 30-minute epoxy. Apply the
epoxy to the exposed wood of the stabilizer. The stabilizer
should then be bolted into place. Refer to Step 4 for
details Use paper towels and rubbing alcohol to remove
any excess epoxy from the fuselage and stabilizer. Allow
the epoxy to fully cure before proceeding.

 Step 9

 Step 10

Use a drill and 1/16-inch (1.5mm) drill bit to drill the
locations for the servo mounting screws.

 Step 11

Apply a few drops of thin CA to each of the holes drilled
in the previous step. This will help harden the wood,
making the screws more secure in their placement.

Position the servo in the opening with the servo arm
facing the front of the fuselage. Mark the locations for the
servo mounting screws using a felt-tipped pen.

66

Section 13: Tail Section Installation

 Step 12

Secure the elevator servo in the fuselage using the
hardware provided with the servo.

 Step 13

Remove the supplied servo arm from the servo. Cut
one arm from a medium-length servo arm so it won't
interfere with the operation of the elevator. Secure the
arm to the output of the elevator servo. Use a felt-tipped
pen to mark the pushrod where it crosses the outer hole
of the servo arm.

 Step 14

Connect the pushrod to the servo arm as shown.

Note: It may be necessary to bend the elevator
pushrod slightly to align with the servo arm.

67

Section 14: Receiver, Battery and Scale Accessories

Required Parts

• Assembled fuselage • Radio tray

• Receiver • Receiver battery

• Foam padding • Receiver cover

• 3mm washer (4) • Canopy (nose)

• Canopy (main) • Canopy (rear)

• Tail gun mount • Side gun mount (2)

• Side gun pod (2) • Guns (12)

• Top turret • Radar dome

• Tail blister • Decal sheet

• Hook and loop strap • Hex wrench: 2.5mm

• 3mm x 12mm machine screw (4)

• 128mmx 45mm x 3mm battery tray

• #2 x 3/8-inch sheet metal screw (4)

The quantity of the following two items will depend on
receiver used.

• Y-harness (2)

• 6-inch (153mm) servo extension (2)

 Step 1

Wrap the receiver in foam and plug any necessary
extensions and Y-harnesses into the appropriate channels.
Secure the receiver to the radio plate using a hook and
loop strap.

 Step 2

Required Tools and Adhesives

• Drill • RC-56 canopy glue

• Phillips screwdriver • Masking tape

• Drill bit: 1/16-inch (1.5mm) • 30-minute epoxy

• 1/4-inch (4mm) foam

Secure the radio plate in the fuselage using four
3mm x 12mm machine screws and four 3mm washers.
Plug the elevator and steering servos into the receiver at
this time as well.

Note: Apply threadlock to the
3mm x 12mm machine screws so
they will not vibrate loose in flight.

68

Section 14: Receiver, Battery and Scale Accessories

 Step 3

Glue the 128mm x 45mm x 3mm battery tray into the front
of the fuselage using 30-minute epoxy. Wrap the receiver
battery in 1/4-inch (4mm) foam. Use hook and loop straps
to secure the battery to the battery tray. Connect a switch
harness between the battery and receiver; install the switch
under the fuselage. We chose to install the switch in the
steering servo access hatch.

 Step 5

Use five #2 x 3/8-inch sheet metal screws to attach the

front greenhouse canopy to the fuselage. There are two
screws on each side, and one positioned in the bottom
center of the canopy underneath the fuselage. Apply a
few drops of thin CA to each of the holes to harden the
surrounding wood.

 Step 4

Measure in 1/8-inch (3mm) from all sides of the cover.
Use a drill and 1/16-inch (1.5mm) drill bit to drill the four
holes for the battery cover screws. Apply a few drops of
thin CA to each of the holes to harden the surrounding
wood. The battery cover is secured to the fuselage using

four #2 x 3/8-inch sheet metal screws.

Note: Make sure to pre-drill for the screws
using a drill and 1/16-inch (1.5mm) drill
bit to prevent damaging the canopy.

 Step 6

Use RC-56 canopy glue to attach the canopy to the
fuselage. Use tape to hold the canopy in position until the
glue fully cures.

69

Section 14: Receiver, Battery and Scale Accessories

 Step 7

Use five #2 x 3/8-inch sheet metal screws to attach the

rear canopy to the fuselage and stabilizer. There are two
screws on either side of the fuselage, two on each side
that go into the stabilizer, and one positioned at the front
of the canopy (as referenced from the fuselage). Apply a
few drops of thin CA to each of the holes to harden the
surrounding wood.

 Step 8

Use hobby scissors to trim the rear gun mount. Use
RC-56 canopy glue to secure the mount to the end of the
fuselage. Use tape to hold the mount in position until the
glue fully cures.

 Step 9

Install the guns by drilling holes in the appropriate
locations. Glue the guns using RC-56 canopy glue.

Note: Make sure to pre-drill for the screws
using a drill and 1/16-inch (1.5mm) drill
bit to prevent damaging the canopy.

Note: If you chose to permanently glue
the horizontal stabilizer to the fuselage,
then the rear canopy can be glued in
place using R/C 56 canopy glue

70

Section 14: Receiver, Battery and Scale Accessories

 Step 10

Glue the turret and guns following the procedure you have
followed in previous steps.

 Step 11

Attach the tailskid to the lower rear of the fuselage using
RC-56 canopy glue.

 Step 12

Use 30-minute epoxy to glue the radio antenna to the
nose wheel steering servo access hatch.

 Step 13

Attach the side guns behind the wing as shown. Note that
the side gun blisters are not symmetrical when installed
on the fuselage. The left gun turret is positioned further aft
of the wing when compared to the right gun turret. (Study
the photos.)

71

Section 14: Receiver, Battery and Scale Accessories

  Step 14

All decals will be factory installed.

  Step 15

Use RC-56 canopy glue to attach the radiators to the wing.

  Step 16

Repeat Steps 13 though 15 to install the remaining
accessories, as there is a right and left to these
accessories.

Recommended Center of Gravity (CG)

An important part of preparing the aircraft for flight is
properly balancing the model. This is especially important
when various engines are mounted.

Caution: Do not inadvertently skip this step!

The recommended Center of Gravity (CG) location for the
B-25 Mitchell is 3
edge of the wing against the fuselage. Mark the location
of the CG on the bottom of the wing as shown. Turn the
airframe upright to balance. If necessary, move the battery
pack or add weight to either the nose or the tail until the
correct balance is achieved. Stick-on weights are available
at your local hobby store and work well for this purpose.

3

/4-in (95.25mm) behind the leading

72

Control Throws

The amount of control throw should be adjusted as closely
as possible using mechanical means, rather than making
large changes electronically at the radio. By moving
the position of the clevis at the control horn toward the
outermost hole, you will decrease the amount of control
throw of the control surface. Moving it toward the control
surface will increase the amount of throw. Moving the
pushrod wire at the servo arm will have the opposite
effect: Moving it closer to center will decrease throw,
and away from center will increase throw. Work with a
combination of the two to achieve the closest or exact
control throws listed.

Elevator Low Rate

7 degrees, 3/8-inch or 8.5mm up/down

Elevator High Rate

13 degrees, 5/8-inch or 16mm up/down

Note: Elevator throw is measured
at inboard end of elevator.

Aileron Low Rate

10 degrees, 3/8-inch or 9.5mm up/down

Aileron High Rate

15 degrees, 9/16-inch or 14mm up/down

Note: Aileron throw is measured
at inboard end of aileron.

Half Flap Position

20 degrees,1-inch or 26mm down

Full Flap Position

40 degrees, 1

Note: Flap throw is measured at
end of flap against the fuselage.

Once the control throws have been set, slide the clevis
retainers over the clevis to prevent them from opening
during flight.

15

/16-inch or 49mm down

Rudder Low Rate

10 degrees, 1/2-inch or 13mm right/left

Rudder High Rate

16 degrees, 13/16-inch or 21mm right/left

Note: Rudder throw is measured at
the widest part of the rudder.

Range Test Your Radio

Range check your radio system before each flying
session. This is accomplished by turning on your
transmitter with the antenna collapsed. Turn on the radio
in your airplane. With your airplane on the ground, you
should be able to walk 30 paces away from your airplane
and still have complete control of all functions. If not,
don’t attempt to fly! Have your radio equipment checked
out by the manufacturer.

73

3 GEAR

INSTALLATION

Retaining nuts

are

optional

Right Lan ding

Gear Cylinder

Nose
Gear

Cylinder

Tee

Fittings

Left Landing

Gear Cylinder

Optional On-board

Pressure Gauge #173

Servo

Arm

Link Rod

Assembly

Control

Valve

1/4" Travel

Maximum

Servo

Fill Valve

(AIR SUPPLY IN)

Fill Chuck

ss

(NOT INCLUDED)

Included in the

VRX Kits

Retract Air line Routing Diagram

roba rt

roba rt

Reach For

** USE THE PROPER LINK ROD ASSEMBLY
FOR THE CONTROL VALVE

(servo, servo arm, and link rod assembly are NOT
included in kit)

Note: The link rod between
the servo arm and the control
valve spool is very important.
Use a nylon clevis at the valve

spool and a simple Z-bend at

the servo arm as shown. The
throw on the servo arm should
allow for approximately 1/4-inch
(4mm) of travel. This will keep
any excessive side loads on the
valve spool minimal and, in turn,
prevent any leakage around the
valve spool seals.

74

Pre-Flight

Charge both the transmitter and receiver pack for your
airplane. Use the recommended charger supplied with
your particular radio system, following the instructions
provided with the radio. In most cases, the radio should
be charged the night before going out flying.

Engine Run-In Instructions

The importance of having both engines run through the
entire flight is typically the most important aspect of flying
a twin engine model. We strongly recommend following
these pre flight engine break-in and tuning instructions.

1) Before you attempt to fly your B-25 Mitchell

we suggest that you do a proper and thorough
break-in of your engines. Start by removing the
fiberglass cowls to allow easy adjustment of the
engine carburetors. We suggest running 1–2 tanks
of fuel through each engine separately following
the engine manufacturer's break-in procedure. It
is important that the engines each have a reliable
idle and a smooth transition thru the mid range
up to full throttle. Adjust the low & high speed
needles as necessary following the instructions
that came with your engine.

2) When you are satisfied with the idle and the

transition from idle to full throttle of both engines
you are now ready to start and run both engines
simultaneously. Start both engines and let them
idle for a few seconds allowing the idle to stabilize
on both engines. Using a tachometer to check the
rpm of both engines is recommended.

Check the radio installation and make sure all the
control surfaces are moving correctly (i.e. the correct
direction and with the recommended throws). Test run
the engine and make sure it transitions smoothly from
idle to full throttle and back. Also ensure the engine is
tuned according to the manufacturer’s instructions,
and it will run consistently and constantly at full throttle
when adjusted.

Check all the control horns, servo horns and clevises to
make sure they are secure and in good condition. Replace
any items that would be considered questionable. Failure
of any of these components in flight would mean the loss
of your aircraft.

The two engines should have rpm readings

within a couple hundred rpm of each other,
but not necessarily identical. Do not change
any of your low speed needle settings to try
and obtain identical idle rpm readings for both
engines. Advance the engines to full throttle
paying attention to the transition. Both engines
should transition in a similar pattern and once
they reach full throttle should have the same or
similar Rpm reading. Again both engines should
be within a couple hundred Rpm of each other.
If the rpm readings are not with in a couple of
hundred rpm, then do not try to lean or richen
the high speed needle. We would recommend
that you either electronically or mechanically
adjust the throttle linkage to bring the higher
rpm engine down to match the other engine.
The majority of your flight will take place with
the engines at or near half power.

3) Once you are satisfied with the idle, transition,
and full powers settings of your engine you need
to replace the cowls and again run the engines.
A fully cowled engine can run at a higher
temperature than an un-cowled engine so it is
important to again check these parameters with
the engine cowls installed. Remember that it is
better to run the engines slightly rich for better
cooling. Never run the engines at peak rpm, but
rather a couple hundred rpm below maximum.

75

Takeoff

Prior to your first flight we recommend that you do
some low speed taxi tests. Use these tests to center
the nose wheel steering to allow for a takeoff straight
down the runway. Once you have finished this be sure
and take a minute to refuel the tanks and take one last
look at the airframe to be sure all screws and control
linkages are secure.

The flaps are not needed if you are taking off from a hard
packed runaway such as asphalt and even fields with
short grass do not require the use of flaps. If you are
taking off from a grass field that is rough or has not been
mowed recently, then we recommend that you use the
half flap position and allow a little extra takeoff roll before
gradually feeding in up elevator. Once you have the B-25
airborne maintain a shallow rate of climb and allow the
model to gain speed prior to making the first turn. The
flaps should be retracted at this point and you should be
entering into the normal traffic pattern. If you are using
retracts then we suggest that you retract the landing gear
prior to retracting the flaps.

Familiarize yourself with the flight characteristics of the
B-25 and practice flying the model at a safe height using
both the mid and full flap positions. Be sure and reduce
the throttles and allow the B-25 to slow a bit prior to
lowering the flaps to the first or mid position. Then lower
the flaps to the full position and adjust power to maintain
straight and level flight. You will find that the B-25 does
not balloon or pitch up if you allow the model to slow
prior to dropping the flaps. We have found that if you
follow this procedure, then you will not need to mix in any
down elevator compensation.

Landing

To begin the landing approach you will need to first lower
the throttles and reduce your flight speed. We recommend
this take place on the downwind leg and that you have the
flaps in the full down position prior to beginning your turn
to the base leg. Allow the B-25 to begin a slow downward
decent and gradually allow the airspeed to bleed off. The
idea is to loose altitude and maintain airspeed by keeping
the nose down in the turn. As you begin your upwind
approach use the throttles to maintain your sink rate
and as you pass over the end of the runway reduce the
throttles to idle and begin to add up elevator and begin
your flare to landing. Should you overshoot the landing
the gradually add power and use the rudders to keep the
B-25 on track. Keep the flaps in the full down position and
begin to set up for a second attempt.

76

Engine Out

A concern that most pilots have when flying a twin is
what to do if and when an engine quits. We have found
that the B-25 will not do anything sudden or abrupt if one
engine should quit while in straight and level flight. The
first thing that needs to occur should an engine quit is to
recognize the situation and then determine which engine
is out. You then will need to determine if you should shut
the other engine down and glide back to the runway or
continue to fly on one engine and enter into the landing
pattern. The B-25 will fly on one engine and will maintain
altitude, but does not have sufficient power to gain
altitude. The key thing to remember when flying with one
engine is to use the rudder to make your turns and then
use ailerons to keep the wings level. You can turn towards
the dead engine if you fly a large gradual turn, but as with
all multi-engine aircraft, turning into the running engine
is safer and should always be done if there is an option.
Remember to maintain airspeed and the flaps are not
needed for an engine out landing.

Remember you do not have enough power to climb out
from a missed landing, so plan your approach the best
you can.

Enjoy flying your Hangar 9 B-25 Mitchell. The model
is very predictable and will surely give you many hours
of enjoyment.

77

2007 Official AMA

National Model Aircraft Safety Code

GENERAL

1. A model aircraft shall be defined as a non-human­carrying device capable of sustained flight in the
atmosphere. It shall not exceed limitations established
in this code and is intended to be used exclusively for
recreational or competition activity.

2. The maximum takeoff weight of a model aircraft,
including fuel, is 55 pounds, except for those flown
under the AMA Experimental Aircraft Rules.

3. I will abide by this Safety Code and all rules
established for the flying site I use. I will not willfully
fly my model aircraft in a reckless and/or dangerous
manner.

4. I will not fly my model aircraft in sanctioned events,
air shows, or model demonstrations until it has been
proven airworthy.

5. I will not fly my model aircraft higher than
approximately 400 feet above ground level, when
within three (3) miles of an airport without notifying the
airport operator. I will yield the right-of-way and avoid
flying in the proximity of full-scale aircraft, utilizing a
spotter when appropriate.

6. I will not fly my model aircraft unless it is identified
with my name and address, or AMA number, inside or
affixed to the outside of the model aircraft. This does
not apply to model aircraft flown indoors.

7. I will not operate model aircraft with metal-blade
propellers or with gaseous boosts (other than air),
nor will I operate model aircraft with fuels containing
tetranitromethane or hydrazine.

8. I will not operate model aircraft carrying pyrotechnic
devices which explode burn, or propel a projectile
of any kind. Exceptions include Free Flight fuses or
devices that burn producing smoke and are securely
attached to the model aircraft during flight. Rocket
motors up to a G-series size may be used, provided
they remain firmly attached to the model aircraft during
flight. Model rockets may be flown in accordance with
the National Model Rocketry Safety Code; however,
they may not be launched from model aircraft. Officially
designated AMAAir Show Teams (AST) are authorized
to use devices and practices as defined within the Air
Show Advisory Committee Document.

9. I will not operate my model aircraft while under the
influence of alcohol or within eight (8) hours of having
consumed alcohol.

10. I will not operate my model aircraft while using any
drug which could adversely affect my ability to safely
control my model aircraft.

11. Children under six (6) years old are only allowed on
a flightline or in a flight area as a pilot or while under
flight instruction.

12. When and where required by rule, helmets must be
properly worn and fastened. They must be OSHA, DOT,
ANSI, SNELL or NOCSAE approved or comply with
comparable standards.

78

2007 Official AMA

National Model Aircraft Safety Code

Radio Control

1. All model flying shall be conducted in a manner to
avoid over flight of unprotected people.

2. I will have completed a successful radio equipment
ground-range check before the first flight of a new or
repaired model aircraft.

3. I will not fly my model aircraft in the presence of
spectators until I become a proficient flier, unless I am
assisted by an experienced pilot.

4. At all flying sites a line must be established, in front of
which all flying takes place. Only personnel associated
with flying the model aircraft are allowed at or in front
of the line. In the case of airshows demonstrations
straight line must be established. An area away from
the line must be maintained for spectators. Intentional
flying behind the line is prohibited.

5. I will operate my model aircraft using only radio­control frequencies currently allowed by the Federal
Communications Commission (FCC). Only individuals
properly licensed by the FCC are authorized to operate
equipment on Amateur Band frequencies.

6. I will not knowingly operate my model aircraft within
three (3) miles of any preexisting flying site without
a frequency-management agreement. A frequency­management agreement may be an allocation of
frequencies for each site, a day-use agreement between
sites, or testing which determines that no interference
exists. A frequency-management agreement may exist
between two or more AMA chartered clubs, AMA
clubs and individual AMA members, or individual
AMA members. Frequency-management agreements,
including an interference test report if the agreement
indicates no interference exists, will be signed by all
parties and copies provided to AMA Headquarters.

7. With the exception of events flown under official AMA
rules, no powered model may be flown outdoors closer
than 25 feet to any individual, except for the pilot and
located at the flight line.

8. Under no circumstances may a pilot or other person
touch a model aircraft in flight while it is still under
power, except to divert it from striking an individual.

9. Radio-controlled night flying is limited to low­performance model aircraft (less than 100 mph).
The model aircraft must be equipped with a lighting
system which clearly defines the aircraft's attitude and
direction at all times.

10. The operator of a radio-controlled model aircraft shall
control it during the entire flight, maintaining visual
contact without enhancement other than by corrective
lenses that are prescribed for the pilot. No model
aircraft shall be equipped with devices which allow it
to be flown to a selected location which is beyond the
visual range of the pilot.

79

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