Aviation Models 30% YAK 54 User manual

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Aviation Models
30% YAK 54 A s sembly Manual
For assistance contact :
Aviation Models
25022 104th Ave SE, Suite E
Kent, WA 98030
ProductInformation: 1 - 253 - 332 - 0786
OrderingHotline: 1 - 866 - 877 - 8621
Copyright © 2005 by Aviation Models, Inc. All rights reserved.
Second edition rev. 5.12.12
please report errors to [email protected]

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WarrantyInformation:
Aviation Models, Inc. guarantees this kit to be free of defects in both material and
workmanship at the time of purchase. This warranty do es not cover any comp o-
nents damaged by use or modification. In no case shall Aviation Models, Inc. l
i-
ability exceed the orig i nal cost of the purchased kit
.
Further, Aviation Models, Inc, r e serves the right to change or modify this warranty
without notice . In that Aviation Models has no control over final assembly or m a-
terials used in final assembly, no liability shall be assumed or accepted for any
damage resulting from the use by user of the final user assembled product. By the
act of using the user assembled product, the user accepts all resulting l i ability.
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 co n-
dition to the place of pu r chas e.
While this kit has been flight tested to exceed normal use, if the plane will be used
for extremely high stress flying such as racing or extreme aeroba t ics the modeler is
responsible for ta k ing steps to reinforce the high stress points. If you do not feel
confident to do this, seek advice from experienced modelers.
Read through this manual before starting constru c-
tion. It contains important warnings and i n structions
concerning the assembly and use of this model.
The pictures in this manual may be of airplanes with different covering schemes.
The planes pictured were of identical construction. Only the color schemes were
different.

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Warning. This is not a toy. If not properly con trolled it
can cause injury or death and prop erty damage.
Included Hardware: Aluminum spinner, fuel tank, aircraft grade aluminum
wing - tube, aluminum main gear, rubber wheels, tail wheel bracket, alum i-
num servo arms, aluminum stab tube for r e movable stab, control horns,
hinges, wheel pants, SAE bolts and nuts, much more.
Specifications:
Wingspan: 87"
Length: 75.5"
Flying Weight: 16lbs
Wing Area: 1411sq.in.
Engine Size: 50cc
CANISTER READY, COWL RING MOUNT, PRE - HINGE - SLOTTED SU R-
FACES,PUSH - RODS AND CONTROL LINKAGES INCLUDED, 5” POLISHED
SPINNER INCLUDED FUEL TANK, WHEELS, LANDING GEAR, MOUNTING
HARWARE, NUTS, BOLTS AND MORE – ALL INCLUDED
FULL PARTS SUPPORT IN STOCK
Additional equipment r e quired:
Computer Radio with at least 8 cha n nels
2 Elevator servos minimum 100 oz/in. of torque each
2 a ileron servos, total torque required not less than 120 oz./in. per wing.
Rudder servo(s) at least 180 oz./in.
Throttle servo
Radio operated engine kill switch or servo operated choke strongly su g gested
Single or dual radio battery packs at least 1650 mAh total
Switch[es]for receiver batteries
Miscellaneousservoextensions.
Flexing in linkage can and will cause flutter of the control surfaces which will
destroy the airplane in just a few seconds. Metal gear se r vos are required.

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Table of Contents
Pag e Subject
5 Open and inspect ev e rything
6 Mount the engine
10 Hinge the control su r faces
12 Mount the hatch and canopy
13 Mount the horizontal stabilizers
13 Install the control horns
14 Install the elevator & aileron servos
16 Throttle and (optional) choke servo installation.
17 Install the landing gear
18 Mount the rudder servo and linkage
18 Install a fuel tank and fuel system
19 Prepare and Mount Cowl
20 Mount the wings
20 Final Checks
21 Check and adjust ba l ance
21 Control throws

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30% Yak 54 Assembly Manual
Step 1. Open and inspect everything
This section should be fairly self e x planatory.
In the large box you should have a f u selage with hatch., wing tube and dual stab
tubes, the elevator/stab asse m blies, the rudder, cowl, wheel pants, cano py, and a
package with the landing gear, tail wheel bracket and mi s cellaneous nuts and bolts.
Use some acetone on a rag to clean the glue off the tubes. Under all of this is a
false floor, and under that you will find the wings with ailerons attached. The
hinges are installed in the elevators and ailerons, but they are not glued, you have
to do that. The hinges for the rudder are in the hardware pack. We have had good
luck with Pro - bond Ultimate and Gorilla glue, both of which are glues that expand
as they dry cure and fill the voids in the hinges and their sockets.
Check everything for shipping da m age and/or manufacturing defects. If there is a
problem, report it to us NOW, not after you start building the plane.
Read the quick start guide at the end of this manual first. It has hel p ful hints
and any errata corrections that may be available.
Before proceeding to any assembly, now is a good time to go over the whole plane
and fix any cosmetic flaws. Some cosmetic flaws are to be expected, this fact is r e-
f lected in the price.
Using This Manual
When you start a construction section, it is a good idea to first read that entire se c-
tion before cutting or drilling or glueing. For example, if you are about to begin
the section called “Mount the Hatch and Canopy”, then read that entire section b e-
fore doing anything else. Toward the end of that section, there is an option to paint
frame line on the inside of the canopy. If you’ve already glued it on, it will be im-
possible. Reading the entire section will give you a good feel of where you are
headed and any options available.

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Knownissuesandimprovements
There are a few areas where, at this unassembled stage, you can improve the final
results of your assembly pr o ject. There are many items that cannot be ad dressed on
the a s sembly line due to cost and possibly because not every improvement would
be welcomed by every builder. Here are a few items that have come up over time.
Go over the covering with a heat gun or iron
. The covering tends to get loose
over tim e and with changes in temperature and humidity. It may have come out of
the box with wri n kles, I can assure you it did not go into the box that way.
Clean out the hinge holes. Without removing any wood, use a very sharp X
- acto
knife and remove any covering that may have been pushed into the hinge holes. It
is very important that the glue sticks to the wood and not to the covering.
Lightweight landing gear and wing tube. In the 30% YAK we have tried to pr
o-
vide as much flexibility as po s sible with regard to e ngine choice. It is sometimes
difficult to be all things to all people. In any case, we have provided very strong
landing gear and wing tubes, which are suitable for any type of engine and flying
but add some weight to the finished plane. Some pilots chose to order carbon f i ber
landing gear and/or wing tubes. This can save several ounces of weight.
Hardening holes. The fuselage sides on this plane are made of balsa which in ce
r-
tain areas is doubled by lite - ply. Using wood screws in balsa is diff i cult be cause
balsa is very soft. It’s a good idea whenever you drill a hole that must accept a
wood screw to put a drop of thin CA into the hole and then if necessary re - drill the
hole. The CA will wick into the wood and harden it, adding strength in that area.
Engine mounting
PLEASE READ THE INSTRU C TIONS FOR STEP 2 COMPLETELY BEFORE
CUTTINGANYTHING!
The first thing to do, before anything else goes in the fuselage, is to get the engine
mounted and aligned with the cowl. This can be a little tricky, so take you r time.
This is perhaps the most difficult part of building this kit, so once you get this
right, you’re on your way to having a great plane. Do this first before you hinge
the ru d der.
Note that the firewall already has a proper amount of right thrust bu ilt in, do not
use any other offsets. When you shim the engine out from the firewall use shims of
equal thickness on all 4 corners so that you do not introduce any other thrust a n-
gles.
This plane is designed around an e n gine of 3 to 4 1/2 pounds. If you pl an to use a
heavier engine (some people plan to use 70 - 75cc, even though that is way ove r-
powered and overweight) it’s a good idea to double the firewall. I have flown this

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plane with a 60cc(4.0 lbs) on the front, and it had an insane amount of zip. With
HiTec 5945’s on the elevators, pull - pull ru d der, and the 4.0 lb. engine on the front,
the CG came out right on the factory recommendation without any batteries inside.
Sim ply place one battery right in front of the wing tube, and one right behind and
your CG will be very close. This is just a guide, each plane should be checked i n-
dividually.
We will prepare our engine box in four steps:
(1) Calculating the engine box length
(2) Cutting the engine box
(3) Marking and preparing our firewall
(4) Glue and re - enforce firew all
(1) Calculating the engine box length
{Engine Cowl length (plus) ¼” prop clearance} (minus) engine length = e n gineboxlength
To determine your engine cowl length, place the cowl on a flat counter and place a
straight edge across the top. With a rule, measure from the flat counter to the bo t-
tom of the straight edge.(see figure 1) Write this number down – it is your cowl
length(CL). NOTE: The back mounting plate of your cowl is r e cessed ¼” from
the e p oxy - glass edge. Use a ¼” shim under your yardstick so that our zero point
is the back of the pl y wood mounting plate.
Measure your engine from the rear of the mounting plate to the surface that the
rear of the prop will rest. (see figure 2) This is your e n gine length (EL)
Figure1 Figure2

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Now, let’s calculate the proper engine box length for your setup.
Cowllength (minus) enginelength=engineboxlength
If you measure the sides of your e n gine box, you will see that they are d ifferent
lengths. This is because some right thrust is built in. Add the 2 measurements and
divide by 2 to get the length at the center.
EXAMPLE: one side measures 6 5/8”(starboard) and the other 6 7/8”(port). Our
average uncut engine box length would be (6 5/8” + 6 7/8”) / 2 = 6 3/4” If we use
the e x ample above and wanted our final engine box length to be 6 1/16”, then 6
3/4”(avg. original length) – 6 1/16”(final length) = 11/16”. I would have to cut
11/16” from each of the e n gine box sides. By cutting both sides the same amount,
we do not change our thrust a n gle.
Now, let’s mark and prepare our fir e wall for engine mounting before we glue it in
place.
First, remove your carburetor and trace your engine mounting plate.
EXAMPLE: CL = 11 3/4” EL = 5 15/16” so,
11.75
- 5.94
engine box = 5.81
now let’s add ¼” so our prop will _ .25
ha ve a little clearance from the cowl 6.06
We would cut our engine box to be 6 1/16” long
After you trace it, cut it out and
then draw diagonals from hole
to hole. When you are done, it
should look similar to this:

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Nextmark your firewall with center lines. Label the firewall “Top” and “front“
with a pencil. Now measure & mark the last 2 lines as shown.
We are now ready to mark and drill our firewall for our engine. Take the engine
mount pattern you made in t he last step and place it over the firewall so that the
center marks of the engine pattern line up with the new centering mark on the fir e-
wall. Rotate until vertical. Use an ice pick or an awl to push though the center of
each of the 4 engine mounting holes. Make sure you make the hole big enough to
find later. When done, drill the firewall through each awl mark with the appropr i-
ate size bit for your engine mounting bolts. (10 - 32 hardened, socket head bolts and
blind nuts will do nicely) Also use a hole saw or jig saw to cut out the center until
yourcarburetor passes througheasily.
We are now ready to epoxy the fir e wall into the engine box. BE SURE TO PUT
THE TOP AT THE TOP AND THE FRONT TO THE FRONT – as labeled in the
previous step. Wipe away excess epoxy. A large blob in the wrong place will pr e-
vent the proper fit of the triangular stock in the next step. After your wipe away
the excess, a little rubbing alcohol on a paper towel will finish the job nicely.
The¼”offset isto
counte r act t he
right thrust. This
willbringthe prop
shaft back to the
centerof thecowl
asite x its.

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After you glue the fire wall to the engine box sides,
reinforce it with 1/2” tr i angle stock on the inside of the
firewall - above and below mid - plate. Drill out the center
hole so that the carburetor passes easily through the
firewall. If you want it to be super strong, bolt 2 sma ll
pieces of aluminum a n gle to the front (see diagram).
Hinging
Like I said, the rest is very easy.
Hinging is a very simple matter. We recommend that you hinge all the control su r-
faces in two steps allowing the glue to dry between steps.
Before you start gluing anything, test fit each control surface. Aileron to wing, el e-
vator to stabilizer, rudder to fin/fuse, with the hinges in place. Make sure the
hinges go in the holes smoothly and that there is ample room for the hinge
“knuckle” so there is no large gap between surfaces. The hinge lines are beveled.
The point of the bevel should be at the center of the hinge pin, this assures that the
hinges are aligned and ce n tered on the hinge line.
Once you are certain that they all go together smo othly, take one surface and r e-
move the hinges. If you have a needle oiler, place 1 or 2 drops of oil into the hinge
and work it back and forth. It’s also a good idea to put some lite oil (like WD40)
on a rag, and to wipe the edges of the hinging surfaces with this rag. The oily res i-
due will keep spilled glue from stic k ing to the ultracote covering. Then wipe off
any excess oil from the su r face. Glue the hinges into the holes securely using the
glue you prefer. I have had good success with Pro - bond polyu rethane (not the pro -
bond yellow furniture glue) because when dr y ing it foams up slightly and fills the
gaps b e tween the hinge and the mounting hole. Pacer Hinge glue works great for
the same reason.