Mountain Models Smooth E User manual

SmoothE Specifications
Length: 31 in. (79 cm.)
Wingspan (SP): 40in. (102 cm.)
Wingspan (SF): 46in. (117 cm.)
Wing Area (SP): 312in2(2013 cm2)
Wing Area (SF): 293in2(1890 cm2) 355in2(2290 cm2)
Weight (without battery): 10-12oz. (284-340 g.)

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Revision History
Date Revision Notes/Comments
5/17/2004 Document initial creation.
Thank you for purchasing the SmoothE. This plane is an aileron/elevator/rudder setup, designed
for the intermediate pilot who wants a fun, small field plane. The SmoothE makes an excellent
aileron trainer if set up for low rates.
This manual covers both the SmoothE SP (Sport Flyer) and the SmoothE SF (Slow Flyer).
Sincerely,
Doug Binder
[email protected]
Mountain Models
465 D Street
P.O. Box 762
Penrose, CO 81240
www.mountainmodels.com
Phone: [phone]
Created by Ross Design Group for exclusive use by Mountain Models.

Mountain Models SmoothE 3
Before You Begin
Before you begin building your SmoothE 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 Cyanoacrylate (CA) glue
• Foam Safe Glue – 5 minute epoxy, white glue, or foam safe medium CA
• 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
• 2" packing tape for covering the wings
• 1/2" fiber reinforced strapping tape
• 4 channel radio
• 4 channel receiver
• GWS EPS350C-C motor with a GWS 9x7 propeller
• 3 micro servos (we recommend either the Hitec HS55s or the GWS Picos)
• Electronic Speed Control (ESC) capable of handling at least 10 amps
• 8 cell 650 mAH KAN NiMH battery pack
Parts List
The following table lists all of the pieces that are in your SmoothE kit.
Number
in Kit Description of Part
Wire
1 3/32” x 14” landing gear wire
3 1/32” x 18” thin music wire for the pushrods and tail wheel
Foam
2 Front wing sections
2 Rear wing sections
Bagged Parts
1 1/8” round x 9” hardwood dowel
2 1 3/4” wheels
2 Internal star wheel retainers
1 1/2” tail wheel
1 6” heat shrink tubing

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Number
in Kit Description of Part
1 6” Velcro strip for mounting the battery and receiver
1 7” double-sided Velcro strip for battery strap
1 Neodymium canopy hold down magnet
1 Washer for canopy hold down
1 4-40 landing gear retaining screw and blind nut
1 #2 x 3/8” motor 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 wood 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.
• Use only foam safe glue to attach the wing sections. Regular CA will dissolve the
foam.
• 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 SmoothE. If you follow these simple
instructions, we can have you flying in no time!
The Entire Process A to Z
Well, I suppose if you want to get technical, it is W to E (wings to electronics), but that
wouldn't make much sense… Hmm, maybe a compass reference would have made more
sense…ah well.
Step 1: Prepare your workspace for assembly.
Step 2: Assemble the wings.
Step 3: Assemble the ailerons.
Step 4: Install the aileron servo.
Step 5: Assemble the fuselage.
Step 6: Assemble and install the stabilizers, rudder, and elevator.
Step 7: Install the elevator and rudder servos.
Step 8: Assemble the landing gear.
Step 9: Install the motor.
Step 10: Attach the electronics.
Step 11: Finish the kit up with the tail wheel, batteries, landing gear, throws, and center of
gravity.
Final Step: On a calm day, find a field without too many trees or light poles and go fly.
Step 1: Preparing Your Workspace for Assembly
Before you begin assembling the SmoothE, 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 Wing
The first thing you are going to assemble is the wing of your airplane. This involves
assembling the spar, attaching the right side wing halves, attaching the left side wing
halves, and then applying the packing tape.
Do not let non-foam safe CA touch the foam. Regular CA will dissolve the foam.
Assembling the Spar
The spar is created by attaching the two balsa spar pieces together to create a single long
spar, and then attaching the plywood spar doubler. Although these pieces are shaped
differently depending on whether you are working on the Sport (SP) or Slow Flyer (SF) wing,
they all go together in the same way.

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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.
For the spar, you will need:
• 1/64" plywood spar doubler for either the SP or SF version (Bagged Parts)
• Foam wing pieces for either the SP or SF version (Foam)
• 2 balsa spar pieces for either the SP or SF version
Sport Wing spar (you will only have this if you have the sport wing)
Slow Flyer spar (you will only have this if you have the slow flyer wing)
! Putting together the spar
1. Position the two balsa spar pieces together to form one long spar, applying thin CA to the
joint once it is snug and flush. It won't take much glue to do this, since it's wicked into the
balsa to form a secure bond.
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.
2. Glue the 1/64” plywood spar doubler to the center of the spar, using the center joint
marks (located on the top edge of the spar) as a guide.
The image above is for the sport wing; however, the slow flyer
spar goes together in the same fashion.
3. Once the glue is dry, carefully remove the spar from the wax paper.
Attaching the Wing Pieces to the Spar
To attach the wing pieces to the spar, you need to understand a bit of terminology…once
you have this, these steps will become much clearer.

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! Putting your wing together
1. Carefully determine which wing piece is which. To do this:
1) Lay the pieces out flat on your worktable.
2) Determine Top and Bottom: Note which side has more curve; the topside
has more of a curve then the bottom side. You now know what is the top and
bottom of your wing.
3) Determine Left and Right: The wings are tapered so that the "fatter" end
goes towards the wing root.
Now your wings are right side up and you know which left and which is right.
2. Position your right rear wing section flat on the worktable. Using the center joint marks
located on the top edge of the spar itself, position the balsa spar against the front of this
wing section, making sure that the spar is lined up with the center marks, and that the
plywood spar doubler is facing forward.
3. Apply foam safe glue to the back of the right-hand portion of the spar. Make sure that the
right rear wing section is still flat on the table, and then press the spar into the spot you
determined in Step 2. Wait for the glue to set up before continuing.
You can speed up the drying rate of CA by increasing the humidity. In the case of the
wing, you can lightly mist the foam with water on the side that does not have CA
applied to it. Once the other side with the CA hits the water, the CA will set up quickly.
In addition, if you choose to use a slower drying glue, you can use painter's tape (it's
the blue tape with low stickiness) to hold your wing pieces together as they dry.
Notice that the spar
doubler is facing forward,
so you can't see it here.

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4. Apply foam safe glue to the front of the right-hand portion of the spar. Make sure that you
line up the right front wing section with the right rear wing section, taking care to ensure
that the left sections will also join up with these right sections properly, and then press the
wing into the spar. Wait for the glue to set up before continuing
The image above shows the right hand wing portion, it is just
turned around so it's facing you.
5. Attach the left wing sections in the same manner that you attached the right wing
sections, gluing the left sections to both the balsa spar, and then to the right wing
sections.
Pay close attention to the alignment of the left wing to the right wing. A poorly
aligned wing will cause the airplane to roll, necessitating the purchase of a new kit.
6. You may choose to round the leading edge of the wing tip with some 200 grit sandpaper.
Test fit the wing into the fuselage to make sure it fits flush. If the
wing does not fit flush, you need to sand the trailing edge where it meets the fuselage. Be
careful not to overdo the sanding.
Taping the Wing
You will apply fiber strapping tape to the wing for strength and to improve its
crashworthiness.
1. Lightly sand the entire wing. Remove all the dust or the tape will not adhere.
2. It is advisable but not essential to lightly mist the entire wing with 3M 77 spray adhesive.
Allow the adhesive to dry for 30 minutes before continuing. You can also use a very light
coating of water based contact cement.
Back of the wing
Front of the wing
Back of the wing
Front of the wing

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The adhesive spray is known to contain acetone which will eat foam. In order to
minimize the problems, you must have a clean nozzle emitting a fine mist, which is
kept a good distance away from the wing and moved quickly. Apply a very light
coating on the surfaces, allow some dry time, and then apply another light
coating, letting it evaporate a bit before bonding. The slight eating of the foam
ends up being part of the bond.
3. Apply a strip of fiber reinforced strapping tape across the bottom of the wing at the spar,
overlapping the wingtip by 1” and wrapping it around the side. Apply a second strip 1” in
front of the spar, also wrapping it around the side. The tape should be tight, but not so
tight as to warp the wings.
4. Apply strapping tape across the top of the wing in the same manner as the bottom.
Covering the Wing
Next, you are going to cover the SmoothE using either colored wing tape, or clear packing
tape. You can use additional colored tapes to give your wing detail.
Choosing a Pattern
Make sure you choose a high contrast pattern using at least two colors, with the darker
color on the bottom and the lighter color on top. This will help you differentiate up from
down and left from right. Try drawing your pattern out on paper before attempting it on
your wing.
For a more in depth discussion of color and visibility, you may want to
read the article "Don't Color Me Gone", written by Dr. Robert Suding, located at:
http://www.ultimatecharger.com/color.html
Applying the Covering Tape
For the SmoothE, we recommend using wing tape (a colored tape) which can be purchased
from Mountain Models or clear packing tape which can be purchased at many office supply
stores.
1. Spray the bottom of the wing with 3M 77 and let it set for about 5 - 15 minutes, until it is
tacky.
See the warning on the previous page regarding the adhesive spray. In order to
minimize the problems, you must have a clean nozzle emitting a fine mist, which is
kept a good distance away from the wing and moved quickly.

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2. Starting on the bottom of your wings, apply the wing tape (don't stretch it, just pull it
from the roll and smooth it on) across the center joint, overlapping the top of the wing by
1/2". Repeat for the top of your wings, overlapping the bottom by 1/2".
3. Starting from the trailing edge and unrolling the tape towards the leading edge, cover the
bottom of your wings, overlapping each piece by 1/2". The tape should also extend past
the center of the wing by 2” and past the wing tip by 1/2".
Keeping your scissors or hobby knife clean is very important to the covering
process. After every five to ten cuts, wipe your blade with a Windex dampened
paper towel. The residue from the tape can make clean cuts almost impossible
since the tape will stick to the blades and just rip instead of cut.
4. Once the bottom of your wings are done, trim the excess tape so that there is only a slight
bit left, which will be used to wrap the edges.
5. Repeat Steps 3-4 for the tops of your wings.
You can use permanent markers to decorate your covering if you don't want to add
weight or covering complexity.
Smoothing out the Covering Tape
Using a heat gun, you are can carefully shrink the tape until you get a glassy finish. This is
not a required step, but will make the surface look more polished.
1. Start shrinking the bottom of the wings first, beginning at the leading edge and moving
towards the trailing edge. Do the middle areas last.
2. Follow the heat gun's path using a covered hand (you can use a thick, clean sock or a
towel), pressing down firmly, smoothing the surface and allowing the tape to adhere to
the adhesive. Be careful around the pushrods as the tape may pull in that area.
3. Once the bottom is done, shrink the top in the same fashion.
Step 3: Assembling the Ailerons
The ailerons will be assembled and then attached to the wing. You will need:
• Aileron pieces (Sport wing)
• Aileron pieces (Slow flyer wing)

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• Aileron control horns
! Putting together the ailerons
1. Remove the aileron pieces from the balsa sheets and align them as shown, making sure
the joints are snug and flush, apply thin CA to the joint.
The image above is for the sport wing; however, the slow flyer
ailerons go together in an identical fashion.
2. Sand a 45◦bevel into the leading edge of the ailerons. Note that the bevel determines
which aileron will be for the right wing and which will be for the left.
3. Glue the control horns to the ailerons so that they come out the top.
4. Sand and paint the ailerons.
Step 4: Installing the Aileron Servo
You will install the aileron servo by cutting a hole in the wing and press fitting the aileron
servo in place. You will need:
• 1/32” music wire (Wire)
• Heat shrink tubing (Bagged Parts)
! Installing the servo
1. Using a sharp #11 Xacto blade, cut a rectangular hole at the center joint of the wing,
directly in front of the spar for the aileron servo. Use your servo as a guide and make the
hole slightly smaller than the servo so that the servo will fit snugly in the hole.
2. Cut the hole all the way through the wing so that the wires will exit the bottom of the
wing, and then press the servo into the hole.
Aileron control
horns

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3. Hinge the ailerons to the wings with clear packing tape, not the wing tape. Leave a 1/32”
gap between the wing and the ailerons to prevent the ailerons from binding. The ailerons
should be aligned with the wing tips.
4. Cut four 3.75” sections of the 1/32” music wire. Bend a small Z bend in one end of each
section.
5. Cut a 1.5” piece of heat shrink and insert two sections of wire to create an adjustable
aileron pushrod (shown in the following picture).
6. Insert one end of the pushrod into the outermost hole of an aileron control horn and the
other end in one of the holes of a servo horn. The hole you chose will determine your
aileron throws. The further out you go on the servo horn, or the further in you go on the
aileron horn, the more throw you will have.
7. Make and install the other aileron pushrod.
8. With the pushrods in place, adjust their lengths so that the ailerons are even and halfway
between following the bottom of the wing and the top of the wing. They will be slightly
drooped.
9. Carefully shrink the heat shrink tubing with a soldering iron then apply a drop of thin CA to
lock the wires in place. Take great care to not get CA on the foam.
Step 5: Assembling the Fuselage
You will assemble the fuselage by first assembling the fuselage crutch and then adding the
fuselage bottom, sides, and top. Follow along carefully as there are a few critical steps along
the way.
Rectangular hole

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The bulkhead names (for example, F5) are listed on the plans.
Assembling the Fuselage Crutch
You will need:
• Blind nut backing plate
• Fuselage crutch and 1/8" landing gear spacer
• F3 - F6 bulkheads
• F7 bulkhead
• Blind nut (Bagged Parts)
! Putting together the fuselage crutch
1. Glue the blind nut backing plate to the F4 bulkhead, using the engraved lines in F4 as a
guide (Figure 1). Press the blind nut into place and then flow a drop of thin CA around the
nut so it is secure.
2. Glue the landing gear spacer to the F5 bulkhead using the engraved lines as a guide
(Figure 2).
Figure 1
Figure 2
F3
F4
F5
F6
F7

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3. Position the F3, F4, F5, F6, and F7 bulkheads into the fuselage crutch. Ensure the
bulkheads are perpendicular with the crutch and then glue all but F4 and F5 in place with
thin CA.
• Make sure that the blind nut is facing forward as shown in the picture and
that the landing gear spacer is between the F4 and F5 bulkheads.
• Make sure that the orientation of the F3 and F7 bulkhead is as shown in
the picture.
Adding the Fuselage Crutch Doublers
You will need:
• Fuselage crutch doublers for left and right side
• F1 and F2 bulkhead
F4
F5
Landing gear spacer
between here
F3
F6
F7
F1
F2

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• Fuselage crutch braces
! Attaching the crutch doublers
1. Following Figures 3 through 5 below, glue one fuselage doubler to the fuselage crutch
assembly, glue the F2 bulkhead to the fuselage crutch doubler, and then glue the other
fuselage crutch doubler in place.
Figure 3
Figure 4
Figure 5
2. Glue the 1/8” landing gear spacer (the F4 and F5 bulkheads, including between them)
using liberal amounts of thin CA to harden it.
3. Glue the F1 bulkhead to the fuselage crutch doublers, making sure that the flat edge and
is to the top and the ridged side is to the bottom.
4. Glue the three fuselage crutch braces to the inside top of the fuselage crutch. Use the
following picture for positioning.
F1 bulkhead,
attached to the
fuselage crutch
doublers.
Fusela
g
e Doubler
F2
Fusela
g
e Doubler

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Make sure that you don't cover the servo screw holes while you're bracing the
fuselage crutch.
Assembling the Fuselage Extensions, Fuselage Bottom, and Remaining Bulkheads
You will need:
• Fuselage bottom, plus the extension piece
• Battery door and reinforcing strips
• Fuselage left and right sides, plus the extension pieces
3 crutch braces

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• F8 and F9 bulkheads
! Putting together the extensions, bottom, and the last of the bulkheads
1. Remove the bottom fuselage extension pieces, removing the center cutout piece. This
piece will become the battery door, put it aside for now.
2. Glue the bottom fuselage extension pieces together, making sure they are firmly pushed
together. This piece is now the fuselage bottom.
3. Glue the reinforcing strips to the battery door and the fuselage bottom. The fuselage
bottom reinforcing strip is the longer one and is positioned at the rear of the battery door.
It needs to overhang the battery opening by 1/8”. Glue the 1/16” ply doubler in front of
the batter door aligning it carefully with the slots as shown.
Top (inside) view of fuselage bottom Outside View
and battery door
4. Glue one set of the side fuselage extension pieces together, making sure they are firmly
pushed together. This piece is now one of the fuselage sides.
F8 F9

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5. Glue the remaining set of the side fuselage extension pieces together, making sure they
are firmly pushed together. This piece is now the other fuselage side.
6. Glue the fuselage bottom to the fuselage crutch assembly, making sure that the
reinforcing strips are facing towards the inside the crutch, not on the outside surface.
7. Glue the F8 and F9 bulkheads to the fuselage bottom.
Completing the Fuselage Buildup
You will need:
• Fuselage rear top
• 1/4" block
Fuselage, shown here
upside down so you can
see the bottom more
clearly
F8
F9
1/4" block

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! Putting together the fuselage sides
1. Glue both of the fuselage sides to the side doublers and the fuselage bottom. Work from
the center of the fuselage crutch forward and then from the center to the rear, gluing as
you go. Do not glue the fuselage sides to the two rear bulkheads F8 and F9 at this
time!
Use the lightening holes in the fuselage side doublers to help align the pieces
before gluing.
2. Position the fuselage sides into the F8 and F9 bulkheads, and then sight down the length
of the fuselage to make sure there is no twist. Twist it straight, if necessary.
3. Once straight, glue the F8 and F9 bulkheads to the fuselage sides.
4. Glue the fuselage rear top to the fuselage sides.
5. Glue the 1/4” block into the fuselage doubler, as shown in the next photo.
Fuselage side
Fusela
g
e rear to
p

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Assembling and Attaching the Motor Mount
You will need:
• Motor mount pieces
• Fuselage front top
! Building and attaching the motor mount
1. Position the motor mount pieces into a 3D rectangle, using the tabs and slots on each
piece. Once everything is square, glue the joints.
2. Once the mount is dry, lightly sand the outside surface so that the motor slides on snugly,
but is not overly tight.
3. Slide the motor mount through the square motor mount support cutouts, making sure that
the rear of the mount is flush with the back of the rear support, and then glue it in place
using thick CA. If there is any slop in the motor mount, angle the front of the stick right
and down from the pilots point of view.