Mountain Models Flashback User manual

Flashback Specifications
Wingspan: 36in. (91cm.)
Length: 36 in. (91cm.)
Wing Area: 265in2(1710cm2)
Weight (without battery): 12oz. (340g.)
Wing Loading (depending on battery): 8.5 – 10.0oz/ft2

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Revision History
Date Revision Notes/Comments
10/04/03 Document initial creation.
Thank you for purchasing the Flashback. This plane is an aileron/elevator/rudder (full
house) setup, designed for the intermediate to advanced pilot who wants a plane with
outstanding performance that will fly in a limited space.
Sincerely,
Doug Binder
[email protected]
Mountain Models
6975 Blackhawk Place
Colorado Springs, CO 80919
www.mountainmodels.com
Phone: [phone]
Fax: [phone]
Created by Ross Design Group for exclusive use by Mountain Models.

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Before You Begin
Before you begin building your Flashback make sure you read and understand all of the
instructions thoroughly.
Additionally, you will need to have the following items. Check to make sure that all of
your parts are there and in good shape, and review a couple quick building tips to make
this whole process go quicker and easier.
What You Will Need
• Smooth and flat work surface
• Wax paper to protect the plans
• Thin and thick Cyanoacrylate (CA) glue
• Hobby knife with #11 blades
• Needle nose pliers
• Wire cutters
• Sanding block with 200 grit sandpaper
• 90°triangle or small square to true the bulkheads and fuselage
• Covering material (if not using the supplied Doculam)
• Sealing iron for applying the covering
• Clear tape for aileron hinges
• 4 channel radio
• 4 channel receiver
• GWS EPS400-C motor with a GWS HD 10x7 propeller
• 3 micro servos (we recommend either the Hitec HS55s or the GWS Picos)
• Electronic Speed Control (ESC) capable of handling at least 15 amps
• 8 cell 950 mAH KAN NiMH battery pack (minimum)
Parts List
The following tables list all of the pieces that are in your Flashback kit.
Description of Parts
Wood
Figure A: 1/16” laser cut balsa sheet
Figure B: 1/16” laser cut balsa sheet

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Description of Parts
Wood
Figure C: 1/16” laser cut balsa sheet
Figure D: 1/16” laser cut balsa sheet
Figure E: 3/32” laser cut balsa sheet
Figure F: 1/16” laser cut balsa sheet
Figure G: 1/16” laser cut balsa sheet
Figure H: 1/16” laser cut balsa sheet
Figure I: 1/8” laser cut balsa sheet

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Description of Parts
Wood
Figure J: 1/32” laser cut balsa sheet
Figure K: 3/32” laser cut balsa
Figure L: 1/8” laser cut balsa sheet
Figure M: 1/64” plywood sheet
Figure N: 1/4” laser cut balsa for cowl
Figure O: 1/16” plywood sheet

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Number
in Kit Description of Part
Loose Wood
2 1/8” x 18” hardwood dowels for leading edge
Wire
1 3/32” x 14” landing gear wire
1 1/32” x 18” thin music wire for the tail wheel and aileron pushrods
Plastic
1 Plastic canopy
1 Doculam clear covering material
Bagged Parts
1 1/8” round x 2.75” hardwood dowel
1 1/4" x 1/4" x 3/4" balsa stick with metal tack
4 Motor mount plywood pieces
2 1 3/4” wheels
2 Internal star wheel retainers
1 1/2” tail wheel
1 6” Velcro strip for mounting the battery and receiver
1 6” double-sided Velcro strip for battery strap
1 Neodymium canopy hold down magnet
1 Tyvek strip for the rudder and elevator hinges and tail wheel
reinforcement (also referred to as CA hinge material)
1 Spectra thread for pull-pull system
6 Micro pushrod connectors
4 Cotter pins for the pull-pull cables
2 #2 x 3/8” motor and battery mount retaining screw
General Building Tips
• Tape your plans to the work table, and then cover them with wax paper to
protect them.
• Balsa is a lightweight and fragile wood, so you do need to be careful with it;
however, you will also need to use a little bit of force to make everything fit
properly, so don’t be too timid.
• Join all of your pieces using thin CA (Cyanoacrylate) glue, unless we tell you
otherwise. In general, only a small amount of CA is necessary to glue parts
together.
• Don’t remove any pieces from the balsa sheets until they’re ready to be used.
That way, parts won’t get mixed up or disappear.
• After you remove pieces from the balsa sheets, carefully remove any of the extra
material from where the piece was attached.
• Don’t over force your pieces together. If they aren’t going together properly,
make sure you have the right pieces and that they are oriented correctly.
• If you want to remove the charred edges caused by the laser cutting process,
dampen a cloth with bleach and gently rub the affected areas. Removing the
char will not increase the strength but will make it look better.

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Assembly Instructions
Okay, so now you are ready to actually build the Flashback. If you follow these simple
instructions, we can have you flying in no time!
The Entire Process Demystified
Step 1: Prepare your workspace for assembly.
Step 2: Assemble the fuselage.
Step 3: Assemble the wings.
Step 4: Assemble the stabilizers, rudder, and elevator.
Step 5: Assemble the ailerons.
Step 6: Assemble the landing gear.
Step 7: Assemble the canopy.
Step 8: Sand, cover all your pieces, and remove the covering where described.
Step 9: Install the tail feathers.
Step 10: Position the wing and ailerons.
Step 11: Install the elevator and rudder servos.
Step 12: Attach the control horns.
Step 13: Install the aileron servo.
Step 14: Install the motor.
Step 15: Attach the electronics.
Step 16: Finish the kit up with the tail wheel, batteries, landing gear, canopy, throws,
and center of gravity.
Final Step: On a calm day, find a field without too many trees or light poles and go fly.
Experienced builders may notice that this building order
goes against the normal building conventions. We have found that fewer pieces get
mangled this way, since you are building the stronger pieces first. For example, the tail
feathers are at the end of the build process instead of the beginning, so that they are
less likely to get underfoot or under cat (which seems to be a recurring problem) and
are being built right before they are attached to the fuselage and each other.
Step 1: Preparing Your Workspace for Assembly
Before you begin assembling the Flashback, you must prepare your workspace.
! Making space in what is probably the most crowded place in your home
1. Lay out the plans on a flat worktable, and then tape them down.
2. Cover the plans with a sheet of wax paper. This will protect the plans from glue.

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Step 2: Assembling the Fuselage
The first thing you are going to assemble is the fuselage of your airplane. This involves
assembling the fuselage sides and bottom, attaching the bulkheads, assembling and
attaching the motor mount, and finally, attaching the sheeting.
It is REALLY important that the fuselage sides are mirror images of each other;
otherwise you will have two left or two right sides, which may work for a profile
plane…
Assembling the Fuselage Sides
For the fuselage sides, you will need:
• 2 Fuselage Pieces (Figure A)
• 1 Fuselage Piece (Figure B)
• 1 Fuselage Piece (Figure C)
! Assembling the sides
1. Remove the fuselage pieces, shown in black, from the balsa sheets.
To remove the pieces, gently flex the balsa sheets until the pieces fall out.
You may find that you need to carefully trim the extra pieces of wood that
originally held the piece to the sheet.
2. Using the notches and grooves on each fuselage side, position them as shown in the
following picture.

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3. Making sure the joints are snug and flush, apply thin CA to each of the joints. The glue
will be wicked into the balsa to form a secure bond, so it won’t take much glue to do
this. Make sure that you are only working on one joint at a time, and that the pieces
are firmly connected before moving to the next joint.
Be careful to keep your fingers as far away from the glue as possible; otherwise,
you might become a part of the model permanently. If you do get stuck, remove
yourself as carefully as possible, trying to avoid taking any of the wood with you.
Once separated, remove the CA glue from your fingers using nail polish remover, or
acetone, making sure you wash your hands thoroughly when done.
4. Once the glue is dry, carefully remove them from the wax paper.
Attaching the Fuselage Reinforcement Pieces
The fuselage reinforcement pieces, or fuselage doublers, are used to reinforce the
fuselage and are placed on the interior walls of each fuselage side.
Yet again, I am just going to quickly mention that the fuselage sides must be mirror
images of each other. This includes making sure that the doublers are mirror images.
But don’t worry, we’re coming to the rescue, the pictures below show both sides just
so there’s no confusion…
For each fuselage side, you will need:
• Fuselage Doubler (Figure B)
Notches and
grooves you use to
create the fuselage
sides

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• Fuselage Doubler (Figure C)
• Fuselage Doublers (Figure D)
• Fuselage Doublers (Figure E)
! Attaching the first set of fuselage doublers
1. Line up the first fuselage doubler (Figure B) with the larger oval slot and the wing
opening, located on the fuselage side.
You will find that if the doubler is in the wrong spot, the larger oval slot in both the
doubler and the fuselage side will not line up.
2. Make sure everything is lined up, including the wing opening, the larger oval slot, and
the outside edge, and then glue the fuselage doubler into place.
Fuselage doublers

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You may find it easier to flow thin CA through the lightening holes on each doubler.
This creates a strong bond without the mess of trying to glue an edge together, or
the weight of using thick CA and pushing the pieces together.
3. Repeat for the other fuselage side, using the fuselage doubler in Figure C.
! Attaching the next set of fuselage doublers
1. Line up one of the fuselage doublers from Figure D with the opposite side of the wing
opening and the slot.
2. Make sure that everything is lined up, including the slot and the wing opening, and
then glue into place.
3. Repeat for the other fuselage side, using the other doubler shown in Figure D.
The fuselage doublers used in this section and the one
above, are used to strengthen the area around where the wing will mount. Since the
wing goes entirely through the fuselage for attachment, this makes the surrounding
area more secure.
! Attaching the final set of fuselage doublers
1. Line up one of the fuselage doublers from Figure E with the slots and the top and
bottom fuselage edges.
Fuselage doublers
Fuselage doublers

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2. Make sure that everything is lined up, including the slots and the top and bottom
edges, and then glue into place.
3. Repeat for the other fuselage side, using the other doubler in Figure E.
These fuselage doublers are used to strengthen the area
around the motor mount. This plane uses a more powerful motor and as such,
requires more support.
Assembling the Fuselage Bottom
Assembling the fuselage bottom includes attaching the fuselage tail, assembling and
attaching the bulkheads, and attaching the whole thing to the fuselage sides.
Attaching the Fuselage Tail
The fuselage tail attaches at the rear of the fuselage bottom and requires the following
pieces:
• Fuselage tail and Fuselage bottom (Figure D)
! Attaching the tail
1. Line up the tail piece with the rear edge of the fuselage bottom, matching the point
and the cutout, as shown in the following picture.
2. Glue the fuselage tail in place.
Assembling and Attaching the Bulkheads
The bulkhead assembly process consists of reinforcing a bulkhead and assembling the
servo tray. The bulkhead attachment process is just attaching the landing gear spacer to
the bulkhead, attaching each of the bulkheads to the bottom of the fuselage, and
attaching the servo tray.
The following image shows the bulkheads with codes that will be referred to on both the
plans and in this section. You will be using all of the fuselage bulkhead pieces shown,
but these pieces are also going to be shown again for each step, highlighted so you
know which pieces are being used at each step.

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Reinforcing the Bulkhead
You are going to need to reinforce the F4 bulkhead so that the fuselage top sheeting,
which is discussed later, has more support.
You will need:
• Bulkhead F4 (Figure A)
• Bulkhead reinforcement piece (Figure C)
! Reinforcing the bulkhead
• Line up the arch of the reinforcement piece with the top edge of the F4 bulkhead.
Do NOT line up the tabs along the side the reinforcement piece; instead use
only the arch section of the pieces for this purpose.
Bulkhead
reinforcement

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Assembling the Servo Tray
You are going to assemble the servo tray next. This piece will be mounted between two
of the bulkheads and will house both your elevator and rudder servos once complete.
You will need:
• Servo tray pieces (Figure L)
One of the center pieces from the servo tray must be
saved even though it seems like waste. It will become the aileron servo block
later…reduce, reuse, recycle!
! Assembling the servo tray
1. Place the largest servo tray piece flat on your workspace table. It’s perfectly
symmetrical, so it really doesn’t matter what side you pick at this point, it will only
matter when you mount the tray in the fuselage.
2. Arrange the two smaller servo tray pieces, we are going to call them servo spacers for
clarity, one on top of the other, lining up the small screw holes. Glue the two pieces
together.
You may find it easier to line up the two pieces by putting a long pin through each
of the screw holes to hold the pieces securely together.
3. Arrange the piece you created in Step 2 so that it sits over the top of one of the holes
in the large servo piece.
4. Using the screw holes for alignment, glue the pieces together.
Flow some thin CA into the screw holes to add some strength. Make sure that you
only use enough to add strength, and that you don’t clog up the holes. Wipe off any
excess glue. We recommend using paper towel to wipe off the excess, as compared
to clothing or flesh, but hey, really that’s your call.
2 small servo
tray pieces
Large servo tray piece

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Attaching the Landing Gear Spacer
You are going to attach the landing gear spacer to the F3 bulkhead. For this section, you
will need:
• F3 Bulkhead (Figure O)
• Landing gear spacer (Figure L)
! Attaching the landing gear spacer
• Line up all of the available edges of the landing gear spacer to the F3 bulkhead,
and then glue the pieces together.
Attaching the Bulkheads to the Fuselage Bottom
In order to attach all of the bulkheads to the fuselage bottom, you are going to need:
• Fuselage Bulkhead F2 (Figure O)

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• Fuselage Bulkheads F4, F5, F7 (Figure A)
• Fuselage Bulkhead F6 (Figure D)
• Fuselage bulkhead F3 (previously assembled)
! Attaching the bulkheads to the fuselage bottom
Make sure you use the step related pictures for reference in this section, more then
you might under normal circumstances. There are a few intricacies that while difficult
to explain are easy to see in the images. So many words, such a large vocabulary…oh
so tongue tied…
1. Position the two small tabs located on the bottom of the F2 bulkhead into the
matching slots of the fuselage bottom, as shown in the picture below.
2. Position the assembled F3 bulkhead into the slots right behind the F2 bulkhead,
making sure that the landing gear spacer is placed between them, also shown in the
next picture.
3. Make sure the bulkheads are perpendicular and fully seated on the fuselage bottom,
and then glue them into place.
4. Position the F4 bulkhead into the appropriate fuselage slots as shown in the following
picture, making sure that the doubler is facing aft (towards the tail), and then glue it
into place.
F2 bulkhead
F3 bulkhead with
landing gear mount
on the inside.
Rear of the plane

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Again, make sure that when you glue the bulkheads in
place that they are perpendicular and fully seated on the fuselage bottom.
5. Position the F5 through F7 bulkheads into the appropriate slots, using the next picture
for guidance. Once they are all positioned, glue them into place.
Attaching the Servo Tray
The servo tray is positioned between the F4 and F5 bulkheads, with the spacers pointed
downwards and forward toward the nose of the plane.
! Attaching the servo tray
1. Slide the servo tray (created in the Assembling the Servo Tray section above) into the
three slots at the center of the F4 bulkhead. The piece will now be on an angle with
the opposite side resting against the F5 bulkhead.
2. Carefully flex the F5 bulkhead so that you can gently push the servo tray down into
the three slots of this bulkhead.
F4 bulkhead. The
doubler should face
towards the rear of
the plane.
F5 bulkhead
F6 bulkhead
F7 bulkhead

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3. Make sure everything is lined up and square, and then glue the tray into place.
Attaching the Fuselage Sides to the Fuselage Bottom
You are going to attach both fuselage sides to the bottom of the fuselage; however,
since you have to install braces inside the fuselage, the gluing of the sides will happen in
stages.
The left and right sides are determined by the pilot’s point
of view. Imagine your pilot sitting in the cockpit, looking out the cockpit window, and
then determine his left and right. This is the point of view that will be used throughout
these instructions.
Attaching the Left Fuselage Side to the Fuselage Bottom
! Attaching the left fuselage side
1. Line up the left fuselage side with the left sides of the bulkheads, pushing everything
gently into place as you move down the fuselage.
Make sure that the doublers are facing the inside of the
fuselage.
Note that the servo tray
is positioned so that the
servo block is pointing
downwards.
Front of the plane

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2. Glue the fuselage side to the fuselage bottom, only from the F2 to the F4
bulkhead.
• Do NOT glue the fuselage side to the bulkheads yet, that will be done later
once the necessary braces are installed.
• You will be gluing the F4 to F7 bulkheads to the bottom of the fuselage once
you have the other side glued into place. This should help prevent warping.
Positioning the Battery Mount Support and Fuselage Braces
You are going to need to position the battery mount support and fuselage braces within
the interior of the fuselage itself. You will need the following pieces:
• 1 Plywood battery mount support/brace (Figure O)
• 2 Balsa fuselage braces (Figure L)
! Positioning the plywood support and fuselage braces
1. Position the plywood support from Figure O into the slot located in front of F4, above
the wing cutout. Glue into place.
2. Position the smaller balsa brace behind bulkhead F3, along the bottom of the fuselage.
Glue it into place.
3. Position the larger balsa brace in front of bulkhead F2, into the slot parallel to the
fuselage bottom. Don’t glue this into place yet, you will do that after you attach the F1
bulkhead.

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Attaching the Other Fuselage Side
Okay, so now you get to attach the other fuselage side to the fuselage bottom. Woo hoo!
It’s really starting to look like a plane now!
Make sure that the doublers are facing the inside of the
fuselage.
! Attaching the right fuselage side
1. Line up the right fuselage side with the right sides of the bulkheads and braces,
pushing everything gently into place as you move down the fuselage.
This process is a bit difficult because the space is kind of tight, and there are a lot of
individual bits to line up. Be patient and try not to use excessive force. Keep in mind
though, if you push too hard, well it adds character…and CA…nothing that everyone
hasn’t done at LEAST once…
2. Ensure that the fuselage is straight, and then glue the right fuselage side to the
bottom and both the right and left fuselage sides to the bulkheads, all between
bulkhead F2 and F4.
Do not glue beyond bulkhead F4 yet. There are a couple
more braces to put in place and it will be much harder if the pieces are glued.
Pl
y
wood su
pp
ort 2 balsa braces