Mountain Models SwitchBack Senior Assembly Instructions Manual

SwitchBack Senior

SwitchBack Senior Specifications

Wingspan: 55.4 in.
Length: 41 in.
Wing Area: 597 sq. in.
Weight (Ready to Fly): 34 to 37 oz.
Wing Loading: 8.2 to 8.9 oz. / sq. ft.

Version 1.05, March 3, 2008

Thank you for purchasing the SwitchBack Sr. This plane is an aileron/elevator/rudder (full
house) setup, designed for the intermediate and higher pilot who wants a plane with
outstanding sport flying performance. Well… that and the SwitchBack groupie in all of us!

This kit is meant for beginner to intermediate builders and low-intermediate pilots (such as a
low wing aileron trainer) and on up for piloting experience.

We started with the original ever so popular SwitchBack, enlarged it by 50%, updated the
construction techniques, and slightly tweaked the design for an even better performing model
than the original.

Sincerely,

Brian Eberwein

[e-mail]

Mountain Models guarantees this kit to be from defects in material and workmanship for the
original purchaser. Since we have no control over the assembly of the final model, we accept NO
liability for any damage or harm caused by the final product resulting from the user. By building
this kit, you accept sole responsibility and liability from its use.

If you, the original buyer are not prepared to accept the liability associated with the use of this
product, return the kit immediately in new and unused condition to us for a refund.

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

WARRANTY

Mountain Models

PO Box 6815

Colorado Springs, CO 80934

www.mountainmodels.com

Phone: [phone]

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Before You Begin

Before you begin building your SwitchBack Sr., make sure that all the balsa sheets and
hardware are present in your kit. In the unlikely event that something is missing, please contact
us immediately and we will send it to you right away.

Make sure you read and understand all of the instructions thoroughly before beginning
assembly of this kit.

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.

Recommended Electronics:

• 3 ea. HS-81 Servos (2 x Ailerons, 1 x Elevator)

• 1 ea. HS-85 Servo (Rudder)

• 2 ea. 6” Servo extensions

• 1 ea. Y-Servo Connector (if using 1 channel for ailerons)

• 1 ea. Mini Receiver (6+ channel for using 2 aileron servos without Y-Connector)

• 1 ea. Scorpion 3008-32 Brushless Outrunner (or 200-300 watt equivalent)

• 1 ea. 3S-2000 LiPo Battery (or higher capacity)

• 1 ea. 35A Electronic Speed Control

Tools You Will Need:

• Smooth and FLAT work surface

• Plastic wrap or Wax paper to protect the work surface

• Thin and Thick Cyanoacrylate (CA) glue

• 5 to 10 Minute Epoxy

• Hobby knife with #11 blades

• Needle nose pliers

• Wire cutters

• Sanding block with 220, 320, and 400 grit sandpaper

• Sealing iron for applying the covering

• Soldering Iron

• Screwdrivers

Items for Finishing:

• 2 Rolls SoLite, Solar Film, or similar lightweight covering

• SolarTrim for adding details to your covering job

• Balsa Wood Filler, lightweight

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Parts List:

• This Manual … If you do not have the manual you are holding, please call us. ☺

• Laser Cut Wood

• 2 ea. Red Pushrod Housings

• 2 ea. 1/16” x 24” Wire

• 2 ea. 1/16” x 12” Wire

• 1 ea. 0.047” x 9” Wire

• 2 ea. 0.060” x 24” Carbon Fiber Rod

• 2 ea. 1/8” Pre-Bent Landing Gear Wire

• Plastic Vac-Formed Canopy and Cowling

• Parts Bag

o 7 ea. 1/16” x 4” x 24” Balsa

o 4 ea. 1/16” x 3” x 24” Balsa

o 4 ea. 3/32” x 4” x 24” Balsa

o 4 ea. 1/8” x 4” x 24” Balsa

o 2 ea. 1/8” x 3” x 24” Balsa

o 2 ea. 3/16” x 4” x 24” Balsa

o 1 ea. 1/8” Plywood Sheet

o 2 ea. 1/8” Lt Plywood Sheet

o 1 ea. 1/16” Plywood Sheet

o 1 ea. 1/8” Plywood “loose” part

o 8 ea. EZ Hinges

o 4 ea. EZ Servo Connectors

o 8 ea. 4-40 T-Nuts

o 8 ea. 4-40 x 3/8” Machine Screws

o 2 ea. 10-32 T-Nuts

o 2 ea. 10-32 Nylon Bolts

o 2 ea. 2” DuBro Wheels

o 1 ea. 1” DuBro Tail Wheel

o 2 ea. 1/8” Wheel Collars

o 4 ea. Magnetic Washers

o 4 ea. Non-Magnetic Washers

o 4 ea. #2 Cowling Mounting Screws

o 3/16” x 5” Dowel

o Double Sided Velcro “Battery Seatbelt”

o 6” Sticky Backed Velcro

o 4 ea. Wire Ties

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General Building Tips

• 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.

Assembly Instructions

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
(which seems to be a recurring problem) and are being built right before they are attached to
the fuselage and each other.

Section 1: Assembling the Fuselage

1. Press the 4-40 blind nuts into the front former and the 10-32 blind nuts into the fuselage wing

mount as shown below. There are 2 plywood circles on the sheet next to the wing mount.
These are to place behind the wing mount when installing the blind nuts so they don’t go into
your table. They are not glued into place. Make sure to install the blind nuts on the “dirty side”
of the parts. Secure the blind nuts with thin CA AFTER you are sure they are fully seated and
flat against the wood.

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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.

2. Slide the 1/8” Lt. Ply former into position on the 1/8” Plywood crutch as shown below. It is a
fairly tight fit, so work it back into position a little at a time. Do NOT glue them together yet.

3. Press the crutch from step 2 and the fuselage wing mount into the 1/8” balsa former as shown
below. Make sure the blind nuts are facing as they are in the image! It’s easiest to lay the
former on your table and press the crutch into the slots. Do NOT glue yet.

4. Press the crutch onto the 1/8” Lt Ply F1 as shown below. Nope, no glue here either.

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5. Assemble the 1/8” balsa rear longerons as shown below. The parts fit best when you assemble
the top/bottom parts with one of the lasered sides up and the other down. Lay them on your
table as shown below so you make a LEFT and RIGHT side. Press the assembled 1/8” rear fuse
parts onto the 1/16” balsa rear parts as shown below. MAKE SURE you assemble them as
shown below, and not upside down! Also make sure that the parts are flush on one side.
Secure these parts with thin CA.

6. Assemble the rear parts to the front 1/8” fuselage parts, as shown below. Place only a couple
drops of thin CA at the joints. Between the front and rear fuselage parts.

7. Press the 3/32” balsa formers into the 1/16” balsa bottom as shown below. The “lasered” side
of the bottom goes “up” and the “lasered” sides of the formers face aft. MAKE Sure this is
right. Lightly tack the parts together with a couple drops of thin CA, AFTER you make sure
they are fully pressed into place.

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8. Press the 1/8” fuselage sides onto the fuselage crutch as shown below. MAKE SURE that the
rear “flush” area of the 1/8” and 1/16” balsa parts is facing to the outside. Do NOT glue this
yet.

9. Set the assembly from step 7 on the table with the fuselage crutch assembly. Carefully slide
the rear /8” longerons into the slots in the formers. You may have to slightly bend and “crack”
the rear longerons where they attach to the front 1/8” balsa sides. You should end up with an
angle, rather than a curve at the joint with the 1/8” balsa former.

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.

10. Install the 1/16” balsa rear top part as shown in the image below. This part is somewhat
fragile until it is installed, so be careful when you are pressing it into place.

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11. Weigh the fuselage down to the table to make sure it stays flat and straight and secure all the
joints with thin CA. ENSURE that the 1/16” balsa rear fuselage bottom is flush with the 1/8”
balsa longerons when you glue these together. Pull the sides together at the front of the fuse,
making sure they are fully pressed into the front former nd secure this area with thin CA.

12. Slide the 1/8” balsa part into place as shown below. Make sure it is flush with the sides and
secure with thin CA. This part is on the 1/8” balsa sheet with one of the fuse front sides.

13. Press the 1/16” balsa sides in place, with the “lasered” side to the inside of the fuselage. You
can use thick CA to glue these sides on, or you can use thin CA after they are on, making sure
they are fully pressed into place. Weights help make sure the sides are fully pressed into
place, as shown below.

¼” Steel plate cut to about 4” squares makes GREAT weights for building. They are
useful for many areas of building and are invaluable took in our shop. Call around
town and see if you can find a metal shop that might have some scrap they can cut
for you. You’ll love having these around. You can also use some 1” square aluminum
tube filled with lead shot and epoxy, bags of lead shot, and even a stack of old
magazines for weights.

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14. Press the rear 1/16” sides into place with the “lasered” side of the part to the inside of the
fuselage, as shown below. BEFORE you glue anything, check to see if the pushrod exit slots
line up with the holes in the rear 3/32” former. If they don’t, you have the parts on the wrong
side. Secure the sides with thin CA.

15. Install the 3/16” rear spine into the formers as shown below. Make sure it is fully seated and
secure it with thin CA.

16. Press the 1/8” plywood landing gear supports into place as shown below. The “lasered” sides
should face to the inside of the fuselage. Clamp them, or otherwise make sure they are fully
pressed into place and against the sides while the glue is drying. If you’re fast, you can use
thick CA. If not, then use some 5 minute epoxy, spread thin.

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