Mountain Models Tantrum User manual

Tantrum Specifications
Wingspan: 37in. (94cm.)
Length: 37in. (94cm.)
Wing Area: 370in2(2388cm2)
Weight (without battery): 10oz. (255g.)
Wing Loading (depending on battery): 5.0 – 6.0oz/ft2

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Revision History
Date Revision Notes/Comments
6/1/03 Document initial creation.
Thank you for purchasing the Tantrum. This plane was designed for the pilot who wants
something more than the everyday parkflyer, and that when using proper mixing, is 3D
capable.
Please keep in mind that this plane is an aileron/elevator/rudder (full house) setup,
intended for the intermediate to advanced pilot. It’s intended to be flown in limited
space situations, without sacrificing its outstanding performance capabilities.
Sincerely,
Doug Binder
[email protected]
Mountain Models
6975 Blackhawk Place
Colorado Springs, CO 80919
www.mountainmodels.com
Phone: [phone]
Fax: [phone]
For the most up-to-date information, please refer to our Web site.
Created by Ross Design Group for exclusive use by Mountain Models.

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Before You Begin
Before you begin building your Tantrum 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
• Sealing iron for applying the covering
• Clear packing tape for hinges
• 5 channel computer radio with aileron/flap mixing, or a 4 channel radio with a Y
cable for the two aileron servos
• 4 or 5 channel receiver
• GWS EPS300C-D motor with a 12x6 propeller
• 4 micro servos (we recommend either the Hitec HS55s or the GWS Picos)
• Electronic Speed Control (ESC) capable of handling at least 10 amps
• Battery pack (we recommend you use at least the following):
♦ 8 cell 600 mAH NiCd (configured )
♦ 8 cell 950 mAH KAN NiMH (configured )
Parts List
The following tables list all of the pieces that are in your Tantrum kit.
Description of Parts
Wood
Figure A: 1/8" laser cut balsa sheet

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

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Description of Parts
Wood
Figure I: 3/32" laser cut balsa sheet
Figure J: 1/32" laser cut balsa sheet
Figure K: 1/16" laser cut plywood sheet
Figure L: 1/16" laser cut plywood sheet
Figure M: 1/64" plywood sheet
Figure N: 5/16" laser cut balsa for cowl
Figure O: 1/4" square x 18” balsa leading edge (x 2)
Figure P: 1/64" plywood sheet

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Number
in Kit Description of Part
Wire
1 1/16" x 14" landing gear wire
1 1/32" x 18" thin music wire for the tailskid and pushrods
Plastic
1 Canopy sheet
Bagged Parts
1 1/8" round x 2.75" hardwood dowel
1 6" x 3/32" heat shrink tubing for the pushrods
2 Internal star washers for wheel retainers
2 3/32" x 3/4" aluminum tube wheel axles
1 6" Velcro strip for mounting the battery and receiver
1 6" double-sided Velcro strip for battery strap
1 1-1/2" clear mushroom head Velcro for canopy closures
2 Wheels
1 Spectra thread (65 pound strength) for pull-pull system
6 Micro pushrod adjusters
4 Cotter pins for the pull-pull cables
2 #2 x 3/8" motor and battery mount retaining screw
2 4-40 wing bolts
4 Washers for the wing assembly
2 Nylon insert locking nuts
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 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 Tantrum. 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 stabilizers, rudder, and elevator.
Step 3: Assemble the ailerons.
Step 4: Assemble the wings.
Step 5: Assemble the fuselage.
Step 6: Assemble the landing gear.
Step 7: Sand, attach the canopy mounts, and cover all your pieces.
Step 8: Install the elevator and rudder servos
Step 9: Attach the control horns
Step 10: Attach the elevator, stabilizers, and the rudder.
Step 11: Install the aileron servos.
Step 12: Install the motor.
Step 13: Attach the wings.
Step 14: Attach the electronics.
Step 15: Finish the kit up with the canopy, batteries, throws, center of gravity, and the
landing gear.
Final Step: On a calm day, find a field without too many trees or light poles and go fly.
Trees and light poles REALLY like to munch on remote
control planes. We say this from experience…trust us.
Step 1: Preparing Your Workspace for Assembly
Before you begin assembling the Tantrum, 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.
Step 2: Assembling the Stabilizers, Rudder, and Elevator
The first things that you are going to assemble are the stabilizers, rudder, and elevator.
When assembled, these are also known as the tail feathers.
Necessary Pieces
• 1- 1/8" laser cut balsa sheet (Figure A)
• 1- 1/8" round x 2.75" hardwood dowel (Bagged Part)

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Assembling the Horizontal Stabilizer
! Putting the pieces together
1. Remove the pieces shown in black from the balsa sheet.
To remove the pieces, gently flex the balsa sheets until the pieces fall out.
You may find that you need to carefully remove the extra pieces of wood
that originally held the piece to the sheet.
2. Position the pieces as shown below. Using the interlocking tabs and grooves, begin
connecting the pieces together to form the horizontal stabilizer.
Assembled Horizontal Stabilizer
Once the pieces are connected together you should be
able to fly it around the room making airplane noises...yes, I do mean BEFORE you
add the glue!
The pieces are pretty snug when you are trying to fit them together. Use
about the same amount of pressure as you would on a jigsaw puzzle,
unless of course you don't like jigsaw puzzles and tend to smash the
pieces in…in that case, be MUCH more gentle then putting together a
puzzle.
3. Using just the tip of your CA applicator, apply a drop of 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.

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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 parts are dry, carefully remove them from the wax paper.
5. Bevel the trailing edge 45°. This should ONLY be done on one side of the piece, and
only for the bottom edge.
Horizontal Stabilizer with Bevel Guide
• To bevel or taper the piece, place it on your worktable with the edge you
are working on lining up with the edge of the table. Using one bar
sander to hold the piece down, use another bar sander to do the actual
sanding.
• While sanding, try to go over the entire edge in a sweeping motion,
avoiding any part of the assembly that is to remain non-beveled. This
will make sure that your bevel angle is even across the entire way.
• Make sure that you sand lengthwise with the grain and not across it, as
this will cause less strain on the wood and less chance of breaking the
pieces.
• Using a tack cloth, carefully remove the balsa dust once you are done
sanding.
Assembling the Vertical Stabilizer
The process for the vertical stabilizer is pretty much the same as for the horizontal
stabilizer; therefore, the following section is mostly for reference purposes, so you can
refer to the pictures as necessary.

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! Putting the pieces together
1. Remove the pieces shown in black from the balsa sheet.
2. Position the pieces and begin connecting them together to form the vertical stabilizer.
Assembled Vertical Stabilizer
3. Glue all of the joints, following the process described for the horizontal stabilizer.
4. Once the parts are dry, carefully remove them from the wax paper.
Assembling the Rudder
! Putting the pieces together
1. Remove the pieces shown in black from the balsa sheet.
2. Position the pieces and begin connecting them together to form the rudder, as shown
in the following image, and then glue all of the joints.
3. Once the parts are dry, carefully remove them from the wax paper.
4. Bevel the entire leading edge 45°. This should ONLY be done on one side of the piece.

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Assembled Rudder with Bevel Guide
Assembling the Elevator
! Putting the pieces together
1. Remove the pieces shown in black from the balsa sheet.
2. Position the pieces and begin connecting them together to form the two halves of the
elevator.
Assembled Elevator (Right Side)
The two halves of the elevator are identical to each
other, one is simply the opposite side of the balsa sheet. In other words, once the
elevator halves are together, simply flip one over, so it is the mirror image of the
other one.
3. Glue the joints for each of the elevator halves, using thin CA.

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4. Join both the halves with the provided dowel, gluing it into place with thick CA.
Completely Assembled Elevator
Step 3: Assembling the Ailerons
Once you have finished building the tail feathers, you can begin assembling the ailerons.
Necessary Pieces
• 1- 1/8" laser cut balsa sheet (Figure B)
! Putting the pieces together
1. Remove the Aileron 1 pieces shown in black from the balsa sheet.
Aileron 1
2. Position the pieces, and then begin connecting them together to form an aileron.
Aileron Assembly
3. Glue all of the joints, following the process described for the horizontal stabilizer.
4. Once the parts are dry, carefully remove them from the wax paper.
5. Remove the Aileron 2 pieces shown in black from the balsa sheet.
Aileron 2
Dowel connecting the two
elevator halves together.

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6. Glue all of the joints, and once dry remove them from the wax paper.
7. Create a 45°°bevel into the leading edge of both aileron assemblies. This should ONLY
be done on one side.
To get a left and a right aileron, make sure you lay out the ailerons so
that both leading edges are facing forward, mirroring each other.
Ailerons with Bevel Guide
Step 4: Assembling the Wings
Once you've finished building the tail feathers and the ailerons, you can begin
assembling the wings. The wings are not interlocking, but do have guides to help you
make sure things go together correctly.
The information within this section applies to building one
wing at a time and then duplicating the entire process for the other wing. But if you
want to, you can build both the wings at the same time. You must be sure to
make a right and a left wing. This is a good reason to at least
start the two wings at the same time.
Attaching the Wing Root and Tip Ribs to the Vertical Spar
For each wing, you will need:
• 1 wing tip rib (Figure B)
• 1 vertical spar (Figure C)

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• 1 wing root rib (Figure D)
! Putting the pieces together
1. Layout the pieces so you can see how things will line up.
2. Hold the vertical spar so that the slots are facing upwards towards the ceiling.
3. Slide the rib you removed from Figure D, known as the wing root rib, into the slot next
to the cutout on the vertical spar.
4. Push the slot, located on the rib you removed from Figure B, known as the wing tip
rib, onto the tab at the outside edge of the vertical spar.
This is where you can begin assembling the second wing, making sure that
it's a mirror image of the first one. Did I mention that this was important??
Wing tip rib from Figure B
Wing root rib from Figure D
V
ertical spar from Figure C
Wing root rib
Wing tip rib

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Attaching the Rest of the Wing Ribs to the Vertical Spar
For each wing, you will need:
• 3 wing ribs (Figure E)
• 1 wing rib (Figure G)
The wing ribs are split across two different balsa sheets.
For the second wing you are going to use two ribs from Figure E and one rib from
Figure G.
! Putting the pieces together
• While you are still holding the vertical spar with the slots towards the ceiling,
match up each wing rib slot with the remaining cutouts, and then slide them into
place.
Wing ribs from Figure E

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Adding the Fuselage Attachment Pieces
For each wing, you will need:
• 2 plywood fuselage attachment pieces (Figure K)
These pieces are also used to reinforce the wings to the
wings, but for the sake of not having to re-type a REALLY long name over and over,
we're just going to call them fuselage attachment pieces for now.
! Putting the pieces together
1. On one of the ribs, you will slide the fuselage attachment pieces behind the vertical
spar into the provided slots in the wing root rib.
2. On the other wing, slide the other fuselage attachment pieces in front of the vertical
spar, using the provided slot.
3. Make sure that you line up the holes on the reinforcements.
Don't glue these joints together yet, you'll glue
everything after the spar caps are attached. This is so that the CA doesn't over
saturate the wood and cause strength issues down the road.
Attaching the Spar Caps
For each wing, you will need:
• 2 spar caps (Figure F)
Fuselage attachment piece,
behind the vertical spar

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! Putting the pieces together
1. Attach the spar caps along the top and bottom of the vertical spar, matching the
cutouts on the spar caps with the placement of the wing ribs.
Pay special attention to which end of the spar cap is facing towards
the root of the wing, and which end is facing towards the wing tip.
The wing tip should be flush along the side edge, with no
overhanging wood.
2. Check to make sure that the rear of each rib is lined up with the other ribs and then
glue all of the joints, making sure that the ribs fit fully into both spars, that both spars
are touching the vertical spar, and that everything is flush, snug, and square,
including the wing reinforcements.
The Tantrum is meant to be a lightweight plane, so make sure you
use the CA as sparingly as possible, but you shouldn’t sacrifice
strength for weight.
Attaching the Stringers
For each wing, you will need:
• 4 stringers (Figure D)
! Putting the pieces together
1. Slide each stringer lengthwise into the four slots at the end of each wing rib, making
sure that they are flush with the wing tip.
Upper spar cap
Lower spar cap

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2. Glue all of the stringers into place, making sure that all of the ribs are straight and
properly lined up within the stringers.
3. Cut the stringers flush with the wing root rib.
Attaching the Trailing Edge
For each wing, you will need:
• 1 trailing edge (Figure D)
! Putting the pieces together
1. Line up the trailing edge with the slots at the end of the wing ribs, so that all of the
slots and tabs fit together.
2. Make sure that everything lines up, push the trailing edge firmly against the ribs, and
then glue the joints.
Attaching the Leading Edge
For each wing, you will need:
• 1/4" leading edge balsa stick
T
railing edge
Stringers

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! Putting the pieces together
1. Use a small bead of thick CA glue on the remaining slot, located on the leading edge of
each of the wing ribs.
2. Align the balsa stick with the outside edge of the wing, pushing it gently into place in
the slots.
3. Hold the leading edge in place until the glue cures, and cut the leading edge flush with
the inner rib then sand the edge from root to wing tip, in order to match the profile of
the wing rib. There will be extra wood overhanging the wing root that will need to be
trimmed so that both sides are flush with the outside, as shown below.
Attaching the Aileron Servo Mount
For each wing, you will need:
• 1 plywood aileron servo mount (Figure P)
Leading edge
Sanded leading edge,
shown on wing tip side

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• 2 plywood servo screw reinforcements (Figure L)
• 1 balsa servo mount reinforcement (Figure H)
! To put the pieces together
1. Using one of the plywood servo screw reinforcements from Figure L, line up its hole
with one of the holes on the aileron servo mount, and glue it to the mount using thin
CA.
Make sure you notice to which side the rectangles are being glued. This
is really important, since the servo mount is attached underneath the
wing with the rectangular pieces facing inside the wings.
2. Using the other servo screw reinforcement, perform the same process as Step 1, using
the other available hole on the servo mount.
3. Mark a line 1/4" on the servo mount, following the guide shown below.
Aileron Servo Mount with Line Guidance
Both servo screw
reinforcements attached to
the aileron servo mount