BME Aircraft PAU Pitts User manual

BME Aircraft
27% Pitts Special Challenger
Congratulations and thank you for choosing BME Aircraft 27 % Pitts
Special Challenger. Before you start assembling, please pay attention to
this step by step instruction manual and follow the steps when
assembling.
I. Beforeassembling
1. Parts check list--
When you open your box of 27 %
Challenger, check all parts inside.
They should include as following:
1x fuselage 1x cowl
2 sets of main wings with ailerons
1 set of stabilizer and 2 elevators
1 set of fin and rudder
2x wing joiners 1x fuse belly
1x upper wing centre joiner
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1 pair of wing strut 1x canopy
1 pair of main wheel / wheel pants 1x hardware pack
1 set of tail wheel assembly 1 set of nylon sticker (3x ORACLE
1x landing gear and block 2x BME Aircraft)
1 set (4x) center cabane
2. Iron all film cover area---
Before you start assembling, Iron all film covered area to make sure
that the film stick on firmly.
3. Cut out film covered area
Cut out the film that covers the opening like servo mount, hinges etc.
II. Start assembling
A. Fuselage—
1. Center cabane
a.Find 4 pcs of aluminum
center cabane from the bags.
There should be two longer
ones and two shorter ones.
Then find the pre-cut 4 slots on
top of the fuse front. Insert 4
cabanes into 4 slots. The
shorter ones goes into the front
slot, longer ones into the rear.
Find 1/2” 4-40 screws from the
hardware pack with the washers
and spring washers to secure
the cabane in place. Thread
lock is required on these
screws.
b. Use two Y-harness, one on
each side of the rear cabane for
aileron connection.
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2. Fire wall installation—
a.The fire wall in this ARF
come unglued for easy access to
install cabane. After the cabane
installation, it’s time to install fire
wall. First try fitting the fire wall
into the engine box. Trim the fire
wall if necessary.
Draw a line 3 3/16” away the fire
wall bottom and the vertical
center line.
To achieve a 3 degree thrust angle,
you must calculate the offset
distance according to the length
from the hub to the mounting plate.
For a 50 cc engine the offset
usually around 0.5 cm. Draw a dot
line as the offset line.
The intersection of two line is your
engine shaft center point.
b.Mark the location of the
mounting screw holes, drill and
insert the T-nuts in place.
c. Glue the fire wall with 30 min.
epoxy. Then glue the included
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balsa tri-block on the corner of the fire wall and box side wall. Install the
gas tank before the fire wall is glued on.
d. Drill and install dowels from the box side wall into the fire wall.
e. The length from fire wall to
the front surface of prop hub
should be 5 3/4”. Install hard wood
block between fire wall and engine
mounting plate if necessary.
3. Landing gear---
a.Screw the wheel axles onto
the landing gear. Then install
wheel using collars to secure
wheel on the far end of the axle.
b. Mark and drill holes for axle
and screws according to the
pre-drilled holes on the landing
gear.
c. Install 4-40 T-nuts to the
inside of the wheel pants for wheel
pant holding screws.
d.Cut a axle access as the photo
shown above.
e. Put both wheel pants on and
secure them with 4-40 screws
remember to use washers and
spring washers.
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f. Install landing gear onto the mounting plate using the provided
screws.
g. Cover landing gear with the balsa block. And secure the block with
provided screws..
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4. Canopy—
a.Try fitting the canopy in place.
Draw a line along the edge of
the canopy.
b. Drill three small holes (same
size as the screws you’d use)
on each side of the canopy.
c. Apply plastic glue along the
inside of canopy frame, then
put back to where it should be
and screw it on.
5. Stabilizer and Vertical fin—(finish the wing assembling before you
proceed this step)
a.Measure and draw a center line of the stab on both side.
b. Take the measurement of the front and rear of opening for stab.

c. Apply the measurement to the
stab symmetrically along the
center line on both side.
d. Cut out the covering along
2mm of the inner side of the
line you just drawn on both
side of the stab.
e. Screw on the lower wing
then insert the stab.
Measure the distance between
wing rear tip and stab front
tip on both side. CA glue the
stab when the measurement is
equal.
f. Insert vertical fin into the slot.
Draw a line along the edge of
fuse.
g. Cut out the covering 2mm
away from the line you just
drawn.
h. Put it back into the slot and
CA glue it in place.
6. Tail wheel assembly---
a.Install tail assembly and shown
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b. Screw the aluminum plate on the rudder as shown.
c. Hook up the spring on both side.
7. Install cowl---
a.Prepare 6 strips of the paper card
(1” x 5”). Drill a hole that a 4-40
size screw can go through.
b. Align the hole on the paper
strip with the hole on the tab
and tape the other side of the
paper strip.
c. Make a donut from 1/8” balsa
as the size of the spinner back
plate.
d. Zap the balsa donut in-between
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the cowl and spinner back plate.
e. Place a prop into the shaft and
tighten it up. Mark and drill
holes through the holes on the
paper strip.
f. Screw the cowl in place with
4-40 screws, then cut out the
balsa donut.
B. Wings
1. Main wings ---
Let’s start with wings. First find the wing joiners from the bags.
There should be two wing joiners, one is a hard wood rectangular
strip and the other is a triangle balsa and hardwood laminated strip.
Also find the upper wing center piece. Try fitting wing joiners into
the wing halves. Put the upper wing center piece in-between two
upper wing halves. Make sure the mounting plate is on the some side
as the servo mount. Then apply 15 min. epoxy into the joiner slot and
wing root surface and glue them together as fitting.
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2. Wing belly—
Now find the lower wing fastening bolts from your hardware pack.
secure lower wing underneath the fuse. Try fitting the belly piece in
place. Draw a line along the side of the belly. Then cut out the
covering film 2mm inside the line. Peer off the cover and glue the
belly in place with medium CA.
3. Wing strut and incidence—
a. Screw on the lower wing, attach wing struts and attach the upper
wing.
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b. Lift up the tail and measure the incidence of the stab until it shows 0
degree. Hold the tail in that position with anything you can use.
Then measure the incidence of the lower wing, it should also shows 0
degree. ( if not, try to correct it by zapping balsa on wing saddle to
achieve 0 degree)
c. Use elastic band to hold upper and lower wing tight through wing
struts. Then measure the
incidence of the upper wing. It
should be between -1 to -1.5
degree and both side should be
the same. If the incidence is not
within this range, try adjusting
it till you achieve the proper
incidence.
d. Mark and drill the tabs through
the holes on wing struts.
C. Control surface
1. Hinges---
a. Clear the covering film around all the
hinge holes.
b. Put a drop of 2 cycle engine oil on the
hinge.
c. Use 30 min. epoxy to glue hinges in
place.
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2. a. Install servos, control horns as your preference. And make up the
push rods square with hinge line.
b. A pull-pull system for rudder is recommended.
3. CG location and control surface throw
a. The CG should be located in front of the leading edge of the lower
wing between 2”-1/2” to the LE. The starting point should be
1 1/2” in front of the LE.
b. The recommended control surface throw is as follow:
aileron 35 degree
elevator 40 degree
rudder 45 degree
You are now ready to test fly your Pitts Special Challenger.
Thanks again for choosing BMEAircraft. Enjoy your flying.
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