Top Flite B-25J Mitchell User Manual

]

Wingspan: 88.5 in [2255mm]

Wing Area: 1036 sq in [66.8 dm

Weight: 17- 19 lbs [7710 – 8620g]

Wing Loading: 38 – 42 oz/sq ft [115 – 129g/dm

Length: 71 in [1795mm]

Scale: 1/9th (11%)

Radio: 8-channel, 13 servos

Hobby Services

3002 N. Apollo Dr. Suite 1

Champaign IL 61822 USA

.46 – .50 cu in [7.5 – 8.0cc] two-strokes

Engine: .70 cu in [11.5cc] four-strokes,

If the buyer is not prepared to accept the liability associated with the use of this

product, the buyer is advised to return this kit immediately in new and unused

condition to the place of purchase.

To make a warranty claim send the defective

part or item to Hobby Services at the address:

Include a letter stating your name, return shipping address, as much contact information

as possible (daytime telephone number, fax number, e-mail address), a detailed

description of the problem and a photocopy of the purchase receipt. Upon receipt of

the package the problem will be evaluated as quickly as possible.

WARRANTY.....Top Flite Models guarantees this kit to be free

from defects in both material and workmanship at the date of purchase. This warranty

does not cover any component parts damaged by use or modiﬁ cation. In no case shall

Top Flite’s liability exceed the original cost of the purchased kit. Further, Top Flite

reserves the right to change or modify this warranty without notice.

In that Top Flite has no control over the ﬁ nal assembly or material used for ﬁ nal

assembly, no liability shall be assumed nor accepted for any damage resulting from

the use by the user of the ﬁ nal user-assembled product. By the act of using the user-

assembled product, the user accepts all resulting liability.

READ THROUGH THIS MANUAL BEFORE STARTING CONSTRUCTION. IT CONTAINS IMPORTANT INSTRUCTIONS AND WARNINGS CONCERNING THE ASSEMBLY AND USE OF THIS MODEL.

Top Flite Models Champaign, IL Telephone (217) 398-8970, Ext. 5 airsupport@top-ﬂ ite.com

doors on the full-size B-25 close both after the gear

has retracted and after it has extended (look at photos

of a B-25 sitting on the tarmac—notice that the gear

doors are closed!). But rather than duplicating the

full-size conﬁ guration (which would require a larger

radio with additional channels, air control valves on

every door, additional pushrods, linkages, air lines,

sequencers and considerable time, expense and

skill), and rather than abandoning functioning doors

altogether, we did it the “hard way” back in the shop by

taking time to ﬁ gure out how to incorporate operating,

scale-appearing landing gear doors that the average

SCALE FEATURES .......................................... 3535

Mount the Nose-Gunner Canopy ........................ 37

Install the Nose-Gunner Cabin ........................... 38

Mount the Top Turret & Machine Guns................ 38

Finish the Tail-Gunner Cabin ..............................39

Mount Side Gun Packs & Waist Gun Windows ...40

Mount the ADF “Football” Antenna ..................... 41

Mount the Propeller Hubs ................................... 41

Apply the Decals ................................................. 41

GET THE MODEL READY TO FLY ....................... 41

Balance the Model (C.G.) ................................... 42

Balance the Model Laterally ............................... 42

ARF builder could both afford and assemble. The

Top Flite B-25 ARF features operating, spring-loaded

doors that use mechanical levers to open and close,

PREFLIGHT .......................................................... 42

Check the Control Directions .............................. 43

Set the Control Throws ....................................... 43

thus eliminating all the aforementioned paraphernalia

that would be required.

And while other scale details including the nose-

gunner interior, cockpit interior, tail-gunner canopy

Identify Your Model ............................................. 43

Charge the Batteries ........................................... 43

Balance Propellers ............................................. 43

Ground Check ..................................................... 43

Range Check ...................................................... 44

and machine guns are not exact replicas, these scale

features still “get the point across” with their presence

and stand-off accuracy. With all this detail also comes

the time commitment to put it all together, but in the

end we know it will all be worthwhile when you’re

executing slow ﬂ y-bys straight down the runway with

the ﬂ aps and gear extended and everybody else at

the ﬁ eld standing by watching.

ENGINE SAFETY PRECAUTIONS .......................44

AMA SAFETY CODE (Excerpts) ......................... 44

CHECK LIST ......................................................... 45

FLYING .................................................................. 45

Mount the Wings ................................................. 45

Takeoff ................................................................ 46

Flight ................................................................... 46

B-25 Engine-Out Flying Procedures ................... 46

Single Engine-Out Procedures ........................... 46

The “Gold” B-25 is also a user-friendly model for breaking

Landing ............................................................... 47

down for transport and set up. Most modelers will simply

SERVO EXTENSION CHARTS .............................48

remove the outboard wing panels allowing the model to

ENGINE MOUNT TEMPLATES ............................ 51

ﬁ t easily into a mini van. If it’s still too big, the inboard

wing panels and vertical and horizontal stabilizers can

also be easily removed with the sturdy building stand

supporting the model during the process.

INTRODUCTION

For the latest technical updates or manual corrections

to this model visit the Top Flite web site at www.top-

ﬂ ite.com. Open the “GOLD EDITION ARFS” link on

the left side of the page and click on image of the B-25

that appears. If there is new technical information or

changes there will be an “Important! TECH NOTICE”

-scale B-25J Mitchell ARF. While no ARF model

Thank you for purchasing the Top Flite Gold Edition

1/9

will provide the level of detail necessary to take

“high-static” at premier scale competitions, you’ll still

be amazed at the level of detail and the number of

scale features included with this model! And we’ve

done our best to balance the level of authenticity and

box on the upper left corner of the page. Click on the

Tech Notice box to read the info.

detail with the requirements for simplicity that an ARF

modeler expects. For example, the main landing gear

TABLE OF CONTENTS

INTRODUCTION ..................................................... 2

Scale Competition ................................................3

Academy of Model Aeronautics ............................ 3

IMAA ..................................................................... 3

SAFETY PRECAUTIONS .......................................3

DECISIONS YOU MUST MAKE .............................. 4

Engine Recommendations ...................................4

Retractable Landing Gear .....................................4

Radio Equipment .................................................. 4

ADDITIONAL ITEMS REQUIRED ..........................5

Hardware and Accessories ................................... 5

Adhesives and Building Supplies ..........................5

Optional Supplies and Tools .................................5

Covering Tools ...................................................... 5

KIT INSPECTION .................................................... 6

ORDERING REPLACEMENT PARTS .................... 6

PREPARATION ....................................................... 9

ASSEMBLE THE WING PANELS ........................... 9

Hinge the Flaps and Ailerons ...............................9

Mount the Engines .............................................. 10

Hook Up the Throttle and Install the Fuel Tank ... 11

Mount the Main Landing Gear ............................ 12

Retract Installation ........................................... 12

Fixed Gear Installation .....................................13

Mount the Fiberglass Nacelle Covers ................. 13

Mount the Main Landing Gear Doors

(Retracts Only) ................................................14

Hook Up the Main Landing Gear Doors .............16

Mount the Cowl ................................................... 19

Mount the Replica Engines ................................. 22

Hook Up the Flaps and Ailerons ......................... 23

ASSEMBLE THE TAIL .......................................... 24

Hinge the Elevators and Rudders ....................... 24

Hook Up the Rudders and Elevators .................. 25

Mount the Nose Gear ......................................... 26

Hook Up the Nose Gear Door

(Retract Only) .................................................. 29

FINAL ASSEMBLY ............................................... 30

Assemble the Cockpit ......................................... 30

Hook Up the Air System ..................................... 31

Complete the Radio Installation .......................... 32

Mount the Inboard Wing Panels .......................... 33

Mount the Outboard Wing Panels .......................34

PROTECT YOUR MODEL, YOURSELF AND

OTHERS. FOLLOW THESE IMPORTANT

SAFETY PRECAUTIONS

1. Your Top Flite B-25J Mitchell ARF should not be

considered a toy, but rather a sophisticated, working

model that functions very much like a full-size

airplane. Because of its performance capabilities, the

B-25 ARF, if not assembled and operated correctly,

could possibly cause injury to yourself or spectators

and damage to property.

2. You must assemble the model according to the

instructions. Do not alter or modify the model, as

doing so may result in an unsafe or unﬂ yable model.

In a few cases the instructions may differ slightly from

the photos. In those instances the written instructions

should be considered as correct.

3. You must take time to build straight, true

and strong.

4. You must use an R/C radio system that is in good

condition and correctly sized engine and components

as speciﬁ ed in this instruction manual. All components

must be correctly installed so that the model operates

correctly on the ground and in the air. You must check

the operation of the model and all components before

every ﬂ ight.

5. If you are not an experienced pilot or have not

ﬂ own this type of model before, we recommend that

you get the assistance of an experienced pilot in your

R/C club for your ﬁ rst ﬂ ights. If you’re not a member

of a club, your local hobby shop has information

about clubs in your area whose membership includes

experienced pilots.

6. While this kit has been ﬂ ight tested to exceed

normal use, if the plane will be used for extremely

high stress ﬂ ying, or if engines larger than ones in

the recommended range are used, the modeler is

responsible for taking steps to reinforce the high

stress points and/or substituting hardware more

suitable for the increased stress.

Fax (765) 741-0057

Tele. (800) 435-9262

Muncie, IN 47302-9252

5151 East Memorial Drive

Academy of Model Aeronautics

ACADEMY OF MODEL AERONAUTICS

If you are not already a member of the AMA, please

join! The AMA is the governing body of model

aviation and membership provides liability insurance

coverage, protects modelers’ rights and interests and

is required to ﬂ y at most R/C sites.

(or 11%). These

Or via the Internet at: http://www.modelaircraft.org

IMPORTANT!!! Two of the most important things you

IMAA

(913) 823-5569

Salina, KS 67401

205 S. Hilldale Road

can do to preserve the radio controlled aircraft hobby

are to avoid ﬂ ying near full-scale aircraft and avoid

ﬂ ying near or over groups of people.

IMAA

The Top Flite B-25 ARF qualiﬁ es as a “giant-scale” model

and is therefore eligible to ﬂ y in IMAA (International

Miniature Aircraft Association) events. The IMAA is an

organization that promotes non-competitive ﬂ ying of

giant-scale model aircraft. If you plan on attending an

IMAA event refer to the IMAA Safety Code at www.

ﬂ y-imaa.org under the “Sanctions” heading in their

site index. IMAA contact information is also available

in Model Aviation, the monthly newsletter magazine

from the AMA. The IMAA can also be contacted at the

address or telephone number below:

3114 Yukon Ave

Fax: (714) 979-7279

Costa Mesa, CA 92626

Bob’s Aircraft Documentation

Telephone: (714) 979-8058

e-mail: www.bobsairdoc.com

SCALE COMPETITION

The scale of this model is 1/9

ﬁ gures were derived from comparing the wing span

and fuselage length of this model to the wingspan and

fuselage length of the full-size. Though the Top Flite

B-25J Mitchell is an ARF and may not have the same

level of detail as an “all-out” scratch-built competition

model, it is a scale model nonetheless and is therefore

eligible to compete in the Fun Scale class in AMA

competition (we receive many favorable reports of

our ARFs in scale competition!). In Fun Scale, the

“builder of the model” rule does not apply. To receive

the ﬁ ve points for scale documentation, the only proof

required that a full size aircraft of this type in this paint/

markings scheme did exist is a single sheet such as a

kit box cover from a plastic model, a photo, or a proﬁ le

painting, etc. If a black-and-white photo is used, other

written documentation of color must be provided.

Contact the AMA for a rule book with full details. See

below for the AMA contact information.

If you would like photos of the full-size B-25J for

scale documentation, or if you would like to study the

photos to add more scale details, photo packs are

available from:

bicycle air compressor. The power cord may have to

be converted from a cigarette lighter connector to

alligator clips or something that can be connected

to your 12V battery. Connect Robart’s air ﬁ ller to the

RETRACTABLE LANDING GEAR

compressor with a length of Robart air line.

Your B-25J Mitchell ARF may be assembled with the

included ﬁ xed landing gear or retractable landing

gear. If ﬁ xed landing gear is used, no additional items

will be needed to install the gear. If installing retracts,

RADIO EQUIPMENT

If ﬂ ying the B-25 with ﬁ xed landing gear seven

channels will be required; one channel for the

ailerons, one for elevator, one for each engine, one

for the rudder, one for the ﬂ aps and one channel for

the nose steering servo. The engines could be linked

with a Y-harness, but it is recommended to link the

throttles electronically via mixing in the transmitter.

retractable main landing gear (ROBQ1624)

Kit—includes pressure vessel, air line tubing,

variable-rate air valve, T-ﬁ ttings (ROBQ2305)

this model is designed for Robart pneumatic retracts.

Following is the complete list of items required to

install the Robart retracts:

❏ Robart #TFB25 Top Flite B-25J ARF pneumatic

❏ Robart #157VRX Large-Scale Deluxe Air Control

❏ #190 Air Line Quick Disconnects (ROBQ2395)

❏ Standard size servo to operate air control valve

Then, the throttles can be “decoupled” using a switch

on the transmitter for starting and tuning the engines

individually. It is also recommended to link the rudder

servos and nose steering servo electronically through

mixing in your transmitter so the nose steering servo

can be trimmed separately from the rudders.

If installing retractable landing gear eight channels

will be required, with an additional standard servo to

operate the air control valve.

(HCAR5500) will be helpful

™

Additionally, a hobby can of compressed air such

as Hobbico Duster

for cycling the retracts during assembly and setup

without having to connect the gear to the air control

valve, ﬁ ller and air tank before it is ready.

Regarding servos, the ailerons, ﬂ aps, nose steering

and air control valve may all be operated with standard

servos (such as Futaba S3003—FUTM0031). A

stronger ball bearing servo with no less than 50 oz.

in. of torque (such as the Futaba 9001—FUTM0075)

should be used on the elevator. Two mini servos with

a torque rating of at least 35 oz.-in. (such as Futaba

S3115—FUTM0415) are required on the rudders.

Note: Keep in mind that the standard servo

recommendations for the ﬂ aps and ailerons are the

minimums. Higher-torque, ball bearing servos could

An air pump will also be required for ﬁ lling the on-

board air tank when you get to the ﬁ eld and it’s time

be used for more ﬂ ight precision.

The following servo extensions and Y-harnesses were

also used in this model. See the diagrams on pages

to ﬂ y. The Robart Hand Pump & Gauge (ROBQ2363)

could be used, but will require considerable time (and

effort!) to ﬁ ll the tank. Instead, we recommend an

electric hobby air compressor (with a pressure gauge).

48-49 that shows where all the extensions are used.

What we use in our R&D shop is simply a small 12V

We, as the kit manufacturer, provide you with a top

quality, thoroughly tested kit and instructions, but

ultimately the quality and ﬂ yability of your ﬁ nished

9. WARNING: Some of the parts in this kit are made

of ﬁ berglass, the ﬁ bers of which may cause eye,

skin and respiratory tract irritation. Never blow into

one of these parts to remove ﬁ berglass dust, as

the dust will blow back into your eyes. Always wear

safety goggles, a particle mask and rubber gloves

when grinding, drilling and sanding ﬁ berglass parts.

Vacuum the parts and the work area thoroughly after

working with ﬁ berglass parts.

model depends on how you build it; therefore, we

DECISIONS YOU MUST MAKE

cannot in any way guarantee the performance of

your completed model, and no representations

are expressed or implied as to the performance or

safety of your completed model.

Remember: Take your time and follow the

instructions to end up with a well-built model that

is straight and true.

This is a partial list of items required to ﬁ nish this

model that may require planning or decision making

before starting assembly. Order numbers are provided

in parentheses.

ENGINE RECOMMENDATIONS

As speciﬁ ed on the front cover of this instruction manual,

the Top Flite B-25J ARF is intended for twin .70 four-

strokes or .46-.50 two-strokes. There isn’t much more

that can be said other than it is unnecessary (as well

as inadvisable) to overpower this model with larger

engines. Engines in the speciﬁ ed range will provide

more than enough thrust to ﬂ y this model in a scale-like

manner with plenty of extra power to perform evasive

maneuvers if the situation arises. Bottom line is with

two-stroke .46’s or four-stroke .70’s you’ll ﬁ nd yourself

cruising around at half-throttle most of the time.

parts (HCAR0667)

K&S #801 Kevlar thread or ﬁ shing Kevlar thread)

(See page 22)

❏ Curved-Tip Canopy Scissors for trimming plastic

❏ Non-Elastic String for stab alignment (such as

❏ 9/32" [7mm] O.D. K+S brass tube for fueling line

❏ Masking tape (TOPR8018)

❏ 3M 77 Spray Adhesive (MMMR1990)

❏ AccuThrow Deﬂ ection Gauge (GPMR2405)

(GPMR2400)

™

❏ CG Machine

❏ Laser Incidence Meter (GPMR4020)

❏ Precision Magnetic Prop Balancer (TOPQ5700)

COVERING TOOLS

A covering iron will be required for tightening the

covering on the model after it is removed from the

Sealing Iron (COVR2700)

Century

box. Following are the covering tools recommended:

❏ 21

Century Iron Cover (COVR2702)

Century Trim Seal Iron (COVR2750)

❏ 21

Micro Torch II

™

The Top Flite B-25 ARF is factory covered with

Top Flite MonoKote ﬁ lm. Should repairs ever

be required, following is a list of colors used on

this model and order numbers for 6' [1.8m] rolls.

(At some hobby shops MonoKote can also be

purchased by the foot.)

Flat Olive Drab (TOPQ0510)

Flat Dove Gray (TOPQ0511)

Flat Black (TOPQ0508)

Panel Line Pen—

White (TOPQ0204)

Note: The stabilizer and wing incidences and engine

thrust angles have been factory-built into the B-25.

However, some technically-minded modelers may

wish to check these measurements anyway. To view

this information, visit the web site at www.top-ﬂ ite.com

and click on “Technical Data.” Due to manufacturing

tolerances which will have little or no effect on the

way the model will ﬂ y, there may be slight deviations

between your model and the published values.

Engine Mount Hole Locator

™

or 4 oz. [113g] Aerosol (GPMR634)

❏ 1 oz. [30g] Thin Pro CA (GPMR6002)

❏ 1 oz. [30g] Medium Pro CA+ (GPMR6008)

❏ CA Applicator Tips (HCAR3780)

assembling this model. These are long-handle Allen

wrenches that will be invaluable for mounting the

cowls and other the scale details.

❏ (4) 6" [150mm] extensions (HCAM2701 for Futaba)

❏ (2) 12" [300mm] extensions (HCAM2711 for Futaba)

❏ (5) 24" [600mm] extensions (HCAM2721 for Futaba)

❏ (1) 36" [910mm] extension (HCAM2726 for Futaba)

❏ (5) Y-harnesses (HCAM2751 for Futaba)

❏ CA Activator 2 oz. [57g] Spray Bottle (GPMR6035),

A minimum 2,000mAh receiver battery could be

used, but you will have to closely monitor the battery’s

capacity and voltage to avoid draining the battery

(TOPR1090)

❏ Pro 30-Minute Epoxy (GPMR6047)

❏ Milled Fiberglass (GPMR6165) -OR- Microballoons

❏ Threadlocker Thread Locking Cement (GPMR6060)

❏ #1 Hobby Knife (HCAR0105)

Ultra 4.8V 4,200 mAh sub C NiMH

™

charges. Following are two suitable battery packs:

❏ HydriMax

too far. A battery larger than 2,000mAh would be

more suitable and provide more ﬂ ight time between

7/64" [2.8mm], 1/8" [3.2mm], 5/32" [4mm], #29 Drill

and 4-40 Tap (or Great Planes 4-40 Tap and Drill

Set (GPMR8101)

❏ #11 Blades (5-pack, HCAR0211)

❏ #11 Blades (100-pack, HCAR0311)

❏ Drill Bits: 1/16" [1.6mm], 5/64" [2mm], 3/32" [2.4mm],

battery w/Futaba connector (HCAM6321)

receiver battery w/Futaba connector (HCAM6335)

ADDITIONAL ITEMS REQUIRED

❏ HydriMax Ultra 4.8V 2,000 mAh AA NiMH receiver

(HCAR0755)

❏ Tap handle (GPMR8120)

❏ Soldering Iron or Hobby Heat

❏ Silver Solder w/Flux (GPMR8070)

❏ Denatured Alcohol for Epoxy Cleanup

❏ Plastic-Compatible Oil for Hinge Pins

❏ Rotary Tool and Cutting Bits (See Page 20)

HARDWARE AND ACCESSORIES

In addition to the items listed in the “Decisions You

Must Make” section, following is the list of hardware

and accessories required to ﬁ nish the B-25. Order

numbers are provided in parentheses.

TOPQ2510)

❏ Rotary Tool Reinforced Cut-Off Wheel (GPMR8200)

❏ Fine-point felt-tip pen (Top Flite

❏ Black Paint for Cockpit Interior

❏ Medium-Grit (220 – 320-Grit) Sandpaper

Tubing (GPMQ4131)

❏ 1/4" R/C Foam Rubber (HCAQ1000)

❏ 3' [900mm] Standard Silicone Fuel

❏ Ernst #124 Charge Receptacle

OPTIONAL SUPPLIES AND TOOLS

Here is a list of optional tools that are also mentioned

❏ Stick-on Segmented Lead Weights (GPMQ4485)

❏ Propellers (and spares) suitable for your engines

ADHESIVES AND BUILDING SUPPLIES

(GPMR8130)

in the manual.

❏ Epoxy Brushes (6, GPMR8060)

❏ Mixing Sticks (50, GPMR8055)

❏ Mixing Cups (GPMR8056)

❏ CA Debonder (GPMR6039)

❏ Dead Center

CA and Epoxy glue are recommended.

™

In addition to common hobby tools and household

tools, this is the “short list” of the most important

items required to build the B-25 ARF. Great Planes

Pro

Foremost, a Great Planes Standard 3/32" Ball Wrench

(GPMR8002) and a Great Planes Standard .050"

Ball Wrench (GPMR8000) are virtual necessities for

REPLACEMENT PARTS LIST

Order Number Description How to purchase

Missing Pieces .................. Contact Product Support

Instruction Manual ............ Contact Product Support

Full-Size Plans ..................................... Not Available

Contact your hobby supplier to purchase these items:

TOPA1700 Wing Set

gun, 2-top turret, 4-external gun packs, (2) 4-7/8"

[125mm] waist machine gun barrels, (2) 4-7/8"

[125mm] tail-gunner machine gun barrels w/4-40

22. Top turret tandem machine guns

23. Nose-gunner machine gun

24. Top machine gun turret canopy

25. R&L side gun packs

26. Nose gear door

27. Nose gear wire

28. 2-5/8" [68mm] nose wheel

29. (7) 6-1/8" [155mm] machine gun barrels (1-nose

TOPA1701 Fuselage Set

TOPA1702 Tail Set (Fins and Stabilizers)

TOPA1703 Left Engine Nacelle Assembly

TOPA1704 Right Engine Nacelle Assembly

TOPA1706 Cowl

threaded inserts

30. Cockpit ﬂ oor (painted ﬂ at black)

31. R&L oil cooler air scoops

32. R&L waist gun windows

TOPA1707 Dummy Engine

TOPA1708 Tail-gunner Cabin

TOPA1709 Gunner Windows

TOPA1710 Wing Tubes

TOPA1711 Landing Gear Set

TOPA1712 Landing Gear Doors (All)

TOPA1713 Cockpit Windscreen

TOPA1714 Cockpit Interior

TOPA1715 Nose-Gunner Window Assembly

TOPA1716 Nose-Gunner Cabin

305mm forward and aft main wing tubes (2, one

end threaded w/nylon inserts), 22 x 295mm outer

panel wing tubes (2), 10 x 150mm outer panel

wing tubes (2, one end threaded w/nylon inserts)

33. Molded plastic ﬁ xed main landing gear blocks

34. R & L main landing gear wires

35. (2) 3-7/8" [98mm] main wheels

36. (2) 420cc Fuel tanks w/hardware

37. 30 x 440mm center main wing tube (1), 10 x

38. Elevator joiner wire

TOPA1717 Machine Gun Set (All)

TOPA1718 Fuel Tank

TOPA1719 Propeller Hub

TOPA1720 Decal Set

TOPA1721 Building Stand

ORDERING REPLACEMENT PARTS

To order replacement parts for the Top Flite

B-25J Mitchell ARF, use the order numbers in the

Replacement Parts List that follows. Replacement

parts are available only as listed. Not all parts are

available separately (an aileron cannot be purchased

separately, but is only available with the wing kit).

Replacement parts are not available from Product

Support, but can be purchased from hobby shops

or mail order/Internet order ﬁ rms. Hardware items

(screws, nuts, bolts) are also available from these

outlets. If you need assistance locating a dealer to

purchase parts, visit www.top-ﬂ ite.com and click

on “Where to Buy.” If this kit is missing parts, contact

Product Support.

KIT INSPECTION

Before starting to build, inspect the parts to make

sure they are of acceptable quality. If any parts are

missing or are not of acceptable quality, or if you

need assistance with assembly, contact Product

Support. When reporting defective or missing parts,

use the part names exactly as they are written in the

Kit Contents list on this page.

Champaign, IL 61822

Top Flite Product Support:

Telephone: (217) 398-8970

3002 N Apollo Drive Suite 1

Fax: (217) 398-7721

E-mail: airsupport@top-ﬂ ite.com

KIT CONTENTS

servo hatches

1. Fuselage

2. R&L inboard wing panels, inboard ﬂ aps, ﬂ ap

ﬂ ap and aileron servo hatches

3. R&L outboard wing panels, outboard ﬂ aps, ailerons,

4. Horizontal stabilizer, elevators, rudder servo hatches

5. R&L vertical stabilizer, rudders

6. R&L ﬁ berglass nacelle covers

7. Fiberglass engine cowls

8. R&L ply/balsa/hardwood nacelle assembly

9. R&L carburetor intakes

10. Replica engines

11. Main landing gear doors

pad, ammo boxes and tops (4)

12. Fiberglass tail-gunner cabin

13. Tail-gunner canopy

14. Nose-gunner canopy bottom

15. Nose-gunner window

16. Cockpit canopy

17. Nose-gunner cabin ﬂ oor, ammo tray, kneeling

mounting bracket

18. Nose-gunner cabin back

19. Tail-gunner cabin bulkhead, armor plate,

20. Pilot/co-pilot seat backs

21. Fiberglass ADF “football” antenna w/magnets

TOP TURRET

WAIST GUN WINDOW/WAIST GUN

SIDE GUN PACKS

CARBURETOR INTAKE

OUTBOARD

WING PANEL

TAIL-GUNNER CABIN

TAIL-GUNNER CANOPY

NOSE-GUNNER CANOPY

THESE ARE THE NAMES OF SOME OF THE SCALE PARTS

NOSE MACHINE GUN

NACELLE COVER

ADF

“FOOTBALL” ANTENNA

NOSE-GUNNER

CANOPY BOTTOM

AIR SCOOP

COCKPIT/COCKPIT CANOPY

OIL COOLER

INBOARD

WING PANEL

TAIL GUNS

❏ 2. Take out the hinges. Add a small drop of plastic-

compatible oil or a small dab of petroleum jelly to the

pivot point of each hinge. Work the oil into each hinge

by pivoting it back and forth a few times.

epoxy. Use a piece of wire to apply epoxy into the hinge

holes in both inboard wing panels and inboard ﬂ aps.

❏ 3. Mix approximately 1/4 oz. [5cc] of 30-minute

❏ 4. Wipe off any excess epoxy from the outside of

all the hinge holes (using your paper towel squares).

One at a time, apply a thin coating of epoxy to one

ASSEMBLE THE WING PANELS

HINGE THE FLAPS AND AILERONS

PREPARATION

PREPARE THE COVERING

During construction there will be several occasions

where epoxy cleanup will be necessary. Instead

to the airframe. Areas of covering that aren’t bonded

to the wood underneath—even if you don’t see any

wrinkles now—may loosen and form wrinkles later.

The best way to seal down and tighten all the covering

is to use a covering iron with a protective covering

❏ Take time now to thoroughly seal the covering

sock to go over the entire model. Push down on the

of wasting whole paper towels, stack three or four

paper towels on top of each other and cut them

into small squares. This will conserve paper towels

and the little squares are easier to use than whole

paper towels. For epoxy clean up dampen the

squares with denatured alcohol.

iron to bond the covering to the wood. If the covering

bubbles you may be using too much heat or leaving

the iron in one position too long. In some areas,

where the sheeting is soft and there is no supporting

structure underneath, the sheeting may bend inward

making it difﬁ cult to remove the wrinkles in those

areas. If this happens, use less pressure on the iron

or don’t press down at all. Note: This procedure takes

time. If you don’t feel like going over the entire model

all at once, start with the inboard wing panels ﬁ rst

and do the rest of the parts as you need them.

❏ 1. Test ﬁ t both inboard ﬂ aps to the inboard wing

panels with the large pivot point hinges. Make sure

the ﬂ aps ﬁ t well and pivot smoothly.

Note: The four-stroke template is for the O.S. Max .70

Surpass and the two-stroke template is for an O.S.

Max .40 or .50 two-stroke. Since the engine mounts

are adjustable, they should ﬁ t other engines in the

size range, but if you are using engines different than

O.S. the positioning of the mounts may have to be

rotated slightly to align the mufﬂ er with the mufﬂ er

cutout in the ﬁ berglass nacelle cover. If this is the

case, you’ll have to mount your engine to the mount

❏ ❏ 2. After the epoxy from the previous step has

hardened, use four 1/4-20 x 2" [50mm] nylon bolts

(indicated by the arrows in the photo) to mount the

left engine nacelle to the bottom of the left inboard

wing panel.

before marking the holes in the ﬁ rewall. Then, place

the nacelle cover over the nacelle on the wing panel

and position the mount (with the engine) so the

mufﬂ er ﬁ ts in the mufﬂ er cutout.

❏ ❏ 4. Once the engine mount holes have been

marked, drill 5/32" [4mm] holes through the ﬁ rewall

at each mark. Remove the template. Push 4-40 blind

nuts into the holes in the back of the ﬁ rewall—if

necessary, trim away any plywood that interferes with

the blind nuts.

❏ ❏ 3. Read the note following this step. Then, cut

out the left Engine Mounting Template (since we’re

doing the left nacelle ﬁ rst) from the back of the manual

for the type of engine you will be using—two-stroke

or four-stroke. Use tape or spray adhesive to hold the

template to the ﬁ rewall. Then use a sharpened piece

of wire or a large T-pin to mark the center of the holes

in the template into the ﬁ rewall.

side of each hinge. Then, insert the hinges into the

wing. When all the hinges are in, working quickly,

coat the other end of the hinges with epoxy. Then,

join both ﬂ aps. Do your best to wipe away any excess

epoxy. Move the ﬂ aps up and down several times to

align all the hinges. Set the wing panels aside and

allow the epoxy to harden.

❏ 6. Join the outboard ﬂ aps and ailerons to the outboard

wing panels the same way using fresh batches of

epoxy. Note that the ailerons use small hinges.

❏ 7. After the epoxy on all the hinges has hardened,

move the ﬂ aps and ailerons up and down several

times to get them moving smoothly and easily.

We’ll install the servos and hook up the ﬂ aps and

ailerons later.

MOUNT THE ENGINES

❏ 1. Use medium CA or epoxy to glue two 8 x 30mm

grooved nylon alignment pegs into the holes in

each engine nacelle. Be certain the peg indicated

protrudes above the base of the nacelle approximately

3/4" [19mm].

6" [150 mm]

SERVO EXTENSION

❏ ❏ 2. Connect a 6" [150mm] servo extension to the

throttle servo. (There are diagrams on pages 48-49

that show all the servo extensions that were used.) Cut

a piece of the 3/8" x 3" [10 x 75mm] black heat shrink

tubing in half and ﬁ t it over the connection between

the servo wire and the extension. Carefully shrink the

tubing with heat from a heat gun or a lighter.

❏ ❏ 3. Place the throttle servo in the mounting

location you will be using—if using the upper throttle

servo mounting location shown, the nacelle will have

to be removed from the wing. Use the mounting holes

in the servo as a guide to drill 1/16" [1.6mm] holes for

the servo mounting screws that came with the servo.

Temporarily mount the servo with the screws. Then,

remove the screws and servo. Add a few drops of

thin CA to each screw hole, allow to harden, and then

remount the servo.

❏ ❏ 4. Hook up throttle using a 2-56 x 17-1/2"

[445mm] pushrod and a nylon clevis on the servo

HOOK UP THE THROTTLE AND

INSTALL THE FUEL TANK

Refer to this photo while hooking up the throttle.

The throttle servo may be mounted in either of two

locations depending on the location of the carburetor

arm on your engine. For most two-stroke engines, it

will be easiest to mount the throttle servo in the lower

location (the location in the bottom of the nacelle next

to the landing gear mount). For some four-stroke

engines (such as the O.S. Max .70 illustrated in this

manual), it will be easiest to mount the throttle in

the upper location (as shown in the photo). If using

the O.S. Max .70, the carburetor will also have to be

reversed to position the carburetor arm on the top.

If using the O.S. .70, remove the engine, reverse

the carburetor and carb arm, and then remount the

engine. However you decide to hook up the throttle,

make certain the pushrod will not interfere with the fuel

tank when it is in position later (you could temporarily

ﬁ t the fuel tank while working on the throttle).

™

❏ ❏ 5. Loosely mount the engine mount to the ﬁ rewall

with 4-40 x 3/4" [19mm] socket-head cap screws

(SHCS) and #4 ﬂ at washers. Adjust the mount to ﬁ t

your engine. Tighten the screws to pull the blind nuts all

the way into the back of the ﬁ rewall. Temporarily clamp

Engine Mount Hole Locator (GPMR8130) or another

method to mark the holes in the mount for the engine

mounting screws. NOTE: The 3/4" [19mm] screws

the engine to the mount so the front of the drive washer

will be 5" [127mm] from ﬁ rewall. Use a Dead Center

holding the mount to the ﬁ rewall are intentionally short

so they do not cut into the front of the fuel tank. Later,

when mounting the engine for the ﬁ nal time, you will

be instructed to add threadlocker to the threads of the

screws so they do not come loose.

❏ ❏ 6. Remove the engine from the mount and take

the mount off the ﬁ rewall. Add a few drops of thin

CA to the edges of the blind nuts in the back of the

❏ ❏ 7. Drill #29 holes at the marks you made in the

engine mount halves for mounting the engine. Tap 4-

ﬁ rewall so they won’t come out.

40 threads into the holes. Remount the mount to the

❏ ❏ 1. Center the throttle servo by temporarily

connecting it to the receiver with a battery and turning

on the radio with the throttle trim on the transmitter

ﬁ rewall and mount the engine to the mount with four

4-40 x 3/4" [19mm] SHCS, #4 lock washers and #4

❏ 8. Mount the other engine to the right nacelle the

ﬂ at washers.

centered. Cut off the unused servo arms so there is

one arm remaining.

same way. Make sure you use the right engine mounting

template for marking the holes in the ﬁ rewall.

❏ ❏ 2. Connect the lines to the air cylinder. Rotate

the ﬁ tting on the down line as shown so it will be

easier to ﬁ t the gear between the rails.

❏ ❏ 8. Mount the left nacelle to the wing with the nylon

bolts. Fit the fuel tank into the nacelle. Then, install and

glue two 3/8" x 3-1/16" [10 x 78mm] plywood fuel tank

sticks from the laser-cut plywood sheet into the slots

❏ ❏ 3. Install the retract and guide the air lines through

the hole in the bottom of the panel, past the ﬂ ap servo

hatch and out root end of the panel—note that the up line

goes through the hole in the back of the nacelle ﬁ rst.

to hold the fuel tank in position. Note: Even though fuel

lines appear in a few of the following photos, there’s

no need to connect them until later after the cowl has

been mounted—the manual will instruct you later.

❏ 9. Return to step 1 and mount the engine, hook up

the throttle and install the fuel tank in the right nacelle

the same way.

MOUNT THE MAIN LANDING GEAR

RETRACT INSTALLATION

(If not mounting retracts, skip to “Fixed Gear

Installation” on the next page.)

Same as we’ve been doing so far, start with the left,

inboard wing panel.

❏ ❏ 1. Determine which color of air line you will be

using for the “up” line and which color you will be

using for the “down” line—the up line connects to the

ﬁ tting on the back end of the air cylinder and the down

line connects to the ﬁ tting on the front of the cylinder

that comes out of the side. Cut the up line to a length

of 21" [530mm] and cut the down line to a length of

18" [460mm].

ﬁ berglass nacelle cover and mounting the landing

gear, it will be easier to have the engine out of the

way. Remove the engine mount from the ﬁ rewall and

end and a brass screw-lock connector with a nylon

retainer and a 4-40 x 1/8" [3mm] socket-head cap

screw (SHCS) on the carburetor arm. Cut a slot in the

ﬁ rewall for the throttle pushrod. Bend the pushrod as

necessary to connect to the carburetor arm.

❏ ❏ 6. For installing the fuel tank, mounting the

set the engine aside.

is recommended—one for the vent/pressure line going

to the mufﬂ er, one for fuel pickup to the carburetor and

a third line for fueling/defueling. This setup will allow

fueling and defueling without having to disconnect

any lines from the carburetor and without having to

turn the model upside-down. To set up the fuel tank

this way, cut two of the aluminum tubes to a length of

1-3/8" [35mm] and leave the other, longer tube as-is.

Assemble the stopper assembly with the aluminum

tubes, bend the longer vent tube upward so it will be

at the top of the tank, and then cut the silicone lines

❏ ❏ 7. Assemble both fuel tanks—a three-line setup

to the correct length so the clunks will not contact the

rear of the tank. Connect the lines to the tubes in the

stopper and ﬁ t the stopper into the tank and tighten

the screw. Make sure the clunks do not contact the

rear of the tank; otherwise, they could get stuck.

Engine Mount

™

MOUNT THE FIBERGLASS NACELLE COVERS

Refer to this photo while mounting the landing gear.

❏ ❏ 1. If you haven’t done so already, remove the left

engine from the engine mount so the nacelle cover

will ﬁ t over the nacelle. Place the left ﬁ berglass nacelle

cover over the nacelle on the wing. Use a pushrod

sharpened on the end or a Dead Center

Hole Locator to mark the location of the three mounting

screws for the nacelle cover into the bottom of the wing.

❏ ❏ 2. Center the landing gear mount on the

mounting rails. Then, drill four 7/64" [2.8mm] holes for

the mounting screws. Mount the landing gear mount

with four #6 x 1/2" [13mm] Phillips screws.

❏ ❏ 3. Mount the left, main landing gear wire into the

landing gear mount using two nylon straps and four #4

x 1/2" [13mm] screws. Mount one of the main wheels

to the landing gear wire with two 5mm wheel collars

and 6-32 set screws with threadlocker on the threads.

❏ 4. Mount the other landing gear to the right inboard

❏ ❏ 2. Remove the nacelle cover. Drill 3/32" [2.4mm]

holes into the wing at the marks. Enlarge the holes

in the plywood mounting tabs in the nacelle cover

only with a 1/8" [3.2mm] drill. Use a long #1 Phillips

wing panel the same way. Add a drop of oil to both

sides of the wheels where they contact the collars.

screwdriver to temporarily mount the nacelle cover to

the wing with four #4 x 5/8" [16mm] Phillips screws,

#4 ﬂ at washers and #4 lock washers.

❏ ❏ 3. Remove the nacelle cover. Add a few drops

of thin CA to each of the screw holes for the nacelle

cover mounting screws. Allow the CA to harden before

mounting the nacelle cover back to the wing.

❏ ❏ 4. Holding the retract centered in the rails with

the strut retracted so it will be out of the way, drill four

7/64" [2.8mm] holes for the mounting screws. Mount

❏ ❏ 5. Use a rotary tool with a ﬁ ber-reinforced cutoff

the retract with four #6 x 1/2" [13mm] Phillips screws.

wheel to cut the one of the main landing gear axles

that came with the retracts to the correct length. File

a ﬂ at spot on the axle for the set screw that mounts

the axle to the strut. Mount the wheel with a drop of

threadlocker on the set screw. Add a drop of oil to

❏ 6. Mount the other retract to the right inboard wing

both sides of the wheel at the strut and the axle.

panel the same way.

FIXED GEAR INSTALLATION

❏ ❏ 1. Assemble one of the landing gear mounts

by using eight 3 x 12mm ﬂ at-head Phillips screws to

mount an aluminum mounting bracket to each side of

one of the molded plastic main landing gear blocks.

1/8"

[3mm]

BALL LINKS FOR REAR DOOR HINGES

DOOR HINGES

TYPE A TYPE B

(These are the hinges that are glued onto the gear doors.)

❏ ❏ 5. Use a single-edge razor blade to cut 1/8" [3mm]

off two nylon ball links—do your best to cut the ends

square. Drill the holes for the screw in the ball links the

rest of the way through with a 5/64" [2mm] drill bit.

❏ ❏ 6. Mount one of the ball links you just cut off

to a “TYPE A” door hinge and mount the other ball

link you just cut off to a “TYPE B” door hinge with a

MOUNT THE MAIN LANDING GEAR DOORS

(FOR RETRACTS ONLY)

If using ﬁ xed landing gear, skip to “Mount the

Cowl” on page 19.

❏ ❏ 1. Remove the nacelle covers from the wing panels.

❏ ❏ 2. Look at the photos on page 15 to see where

the door hinges are mounted. Use coarse sandpaper

to roughen the inside of the left nacelle cover where

the landing gear door hinges will go.

❏ ❏ 4. Re-mount the nacelle cover to the wing.

If you’ve mounted retracts, read the Hot Tip that

follows. Then, cycle the gear a few times to make

sure everything works. (If necessary, use a sanding

drum to enlarge the half-round notch at the front of

❏ ❏ 3. Use a hobby knife to scrape away the black

paint from the recesses inside one set of ﬁ berglass

main landing gear doors so the glue will adhere for

the door hinges.

The landing gear can be easily cycled with a can

of compressed air such as a Hobbico Duster. Cut

two 1" [25mm] pieces from the tube that comes with

the opening in the nacelle cover.)

the can. Fit the tubes into the ends of both air lines

❏ ❏ 4. Place the doors on the left nacelle cover. Use

masking tape to tape the doors together, and then

tape them to the nacelle cover.

coming from the wing that are connected to the

gear. Connect one tube to the Duster to extend the

gear and connect the other tube to retract the gear.

❏ 5. Mount the right nacelle cover the same way.

NACELLE COVER

GEAR DOOR

As best as you can, get the bases of the hinge

to lay flat on the door and on the nacelle cover.

Make sure the glue press up and fills the holes

of the mounts.

of each hinge base so glue will adhere. Test ﬁ t the hinge

assemblies to the doors and nacelles—each hinge

assembly should be in the location and orientation

shown. If necessary, adjust the length of any of the

ball links by cutting them shorter so the hinges will rest

❏ ❏ 10. Use coarse sandpaper to roughen the bottom

ﬂ at, or nearly ﬂ at, on the doors and nacelle.

❏ ❏ 11. Use epoxy mixed with milled ﬁ berglass or

micro balloons to glue each door hinge to the doors.

After the epoxy has hardened glue each nacelle

hinge to the nacelle.

❏ ❏ 12. After the epoxy on the door hinges has

hardened, remove the masking tape and open

the doors.

❏ 13. Hinge the doors to the other nacelle the

same way.

1/16"

[1.5mm]

BALL LINKS FOR FRONT DOOR HINGES

2-56 x 3/8" [9.5mm] screw, #2 lock washer and #2

ﬂ at washer. These hinges will go on the aft end of the

gear doors.

❏ ❏ 7. Cut 1/16" [1.5mm] from two more nylon ball

❏ ❏ 9. Snap the ball link balls of the nacelle hinges

onto the ball links on the door hinges as shown.

links. Mount each ball link to another TYPE A and

TYPE B door hinge. These door hinges will be for the

front of the gear doors.

❏ ❏ 8. Prepare two “TYPE A” nacelle hinges and

two “TYPE B” nacelle hinges by mounting an 0-80

ball link ball in the bottom hole of each hinge with an

0-80 nut and a drop of threadlocker on the threads.

3/8"

❏ ❏ 6. Remount the lever mount to the nacelle with

the #2 x 3/8" [9.5mm] button-head screw. Fit a brass

bushing into the plywood bellcrank lever as shown.

Mount the bellcrank lever to the lever mount and the

nacelle with the #4 x 5/8" [16mm] screw. Tighten the

screw as much as possible without causing the lever

to bind.

[10mm]

❏ ❏ 7. Bend a hook on each end of the spring where

shown and cut off the excess wire. Connect the spring

to the bellcrank lever and the lever mount as shown—

there should be just enough tension in the spring to

pull the lever to the lever stop. Later, if necessary,

the spring tension can be adjusted by using another

notch in the lever mount. Move the bellcrank up and

down to make sure it moves smoothly with a small

amount of resistance from the spring. Make any

adjustments necessary.

❏ ❏ 8. Mount the nacelle cover with the doors

attached to the wing panel. Note: If the doors ever

require removal for repairs/servicing, do not pop off

the ball links. Instead, unscrew the 2-56 screws from

the ball links.

If necessary, trim

the lever here.

❏ ❏ 9. Test the “action” of the landing gear and

the lever mechanism by operating the system with

❏ ❏ 3. Use the other hole in the lever mount as a

guide to drill a 3/32" [2.4mm] hole into the nacelle for

the #4 screw that will hold in the bellcrank.

❏ ❏ 4. Remove the lever mount. Temporarily thread

a #4 x 5/8" [16mm] Phillips screw into the larger hole

you drilled. Remove the screw. Add a few drops of

thin CA to both screw holes and allow to harden.

❏ ❏ 5. Use medium CA to glue a 5mm I.D. x 12mm

O.D. thin, plastic washer to the front surface of the

plywood bellcrank lever. (Six washers are included in

the kit—two are for the levers on the main landing

gear doors, one is for the lever on the nose landing

gear and three are left over for spares.) The easiest

way to glue on the washer is to pick it up with a hobby

knife, apply a thin ﬁ lm of thin CA to it and place it

on the lever centered over the hole. Then turn the

lever over and press down over a piece of plastic ﬁ lm

(from a sandwich bag or leftover MonoKote backing)

or wax paper.

HOOK UP THE MAIN LANDING GEAR DOORS

❏ ❏ 1. Glue a 1/8" x 1/2" [3 x 15mm] hardwood

dowel lever stop into one of the lever mounts as

shown. The end of the stop should be ﬂ ush with the

other side of the mount.

Use this photo for the next 8 steps.

❏ ❏ 2. Hold the lever mount on the back of the

nacelle as shown—the outer edge of the mount

should be even with the side of the nacelle and the

top of the mount should be even with the bottom edge

of the nacelle (where indicated by the arrows). Using

the small hole in the right side of the lever mount as

a guide, drill a 1/16" [1.6mm] hole into the nacelle.

Mount the lever mount to the nacelle with a #2 x 3/8"

[9.5mm] button-head Allen screw.

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Top Flite B-25J Mitchell User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual