Bengtson Company Albatros CIII 38 User manual

Albatros CIII 38”
Copyright© 2004-11 M.K. Bengtson All Rights Reserved Rev 07/11
Albatros CIII 38”
R/C Scale Model Instructions
CONTACT INFORMATION
Designed by
M.K. Bengtson
Manufactured and Distributed by:
Bengtson Company
e-mail: [e-mail]
Web Site: www.aerodromerc.com

Albatros CIII 38”
Copyright© 2004-11 M.K. Bengtson All Rights Reserved Rev 07/11
Albatros CIII
Thank you for purchasing the Albatros CIII model for electric
flight.
THE MODEL
A semi scale adaptation of the Albatros CIII, this model is
designed to be easy to build and exciting to fly.
POWER SET UP
The model can be set up to be powered by the 6V S400
motor and the MP Jet 3.4:1 Gearbox and a 10x4.7 APC
prop. Battery power pack can be 8 600maH Nicads or an
equivalent weight Nimh
R/C GEAR
A four function mini receiver and four micro servos are all
that are required. Hitec HS-50 sub micro servos are
required for the aileron servos.
Model Specifications
More than 250 laser cut parts
Scale: 1/12
Channels: R/E/A/T
Wingspan: 38"
Wing Area: 394 sq in.
Weight: 25 Oz. ready to fly
Power system: Designed for 6V S400 with MP Jet 3.4:1
gearbox.
4 micro servos Ailerons (HS-50's)
Balsa and Litespan or Polyspan covering
Prop: 9x6
Wheels: Balsa, plywood, Neoprene foam cord
tires, Brass tube hub Paper card wheel
cones
Airfoil Type: Flat Bottomed
Cowl: N/A
Spinner: N/A
Decals: Available on website
BUILDING THE MODEL
BEFORE STARTING
A note about the photos: The photos were taken of a
prototype and the parts supplied may look slightly different
from them. However, the concepts illustrated are the same.
Robert Stinson built the Albatros CIII prototype.
WINGS
Wing Construction
Pin down, over the plan, the t/e, spars and wing tip, gluing as
required. Add the leading edge stock after the basic frame is
done as the stock is inserted in a rotated fashion. Add the
wing tips and align the front tip along the center of the
leading edge. Sand the leading edge stock to be rounded
and meet the ribs.
Lower wing
The leading edge of the aileron is rounded over with
sandpaper to make the aileron movable with a minimum
gap. The trailing edge of the wing in that section is left flat.

Albatros CIII 38”
Copyright© 2004-11 M.K. Bengtson All Rights Reserved Rev 07/11
FUSELAGE CONSTRUCTION
The fuselage is built as two side structures, which are then
joined over the plan. This system not only keeps each stage
simple, but it also helps to ensure a straight fuselage.
Building of the Right Side of the Fuselage
Begin by building two fuselage side frames over the plan and
allow to dry.
Join the two frames over the plan with cross braces and the
tail skid mount F12 and Vertical stabilizer mount F11.
Check, check and check again that this and ALL other
structures remain perfectly aligned. Former F1 is also
angled a bit for down thrust. Place F11 and F12 carefully.
They serve to position the vertical stabilizer and tail skid.
Use a length of 1/8”x1/4” balsa stock at the end of the
fuselage.
Adding the Decking
Add all the stringers and formers, and carefully trim to size
and fit 1/16” sheeting. Some have also sheeted the fuselage
sides with 1/32” balsa as well. Keep in mind that excess
weight in the tail is to be avoided, so use these sheeting
options with the lightest balsa available.
Soak the nose of the fuselage sides in hot water for 10
minutes to soften the wood. This process allows the sides to
bend to conform to the motor mount and make the required
taper.
Adding The Undercarriage Plates
LANDING GEAR
Assemble ply landing gear parts and use them as templates
for bending music wire reinforcements. Soak the ply
portions with thin CA for strength. Secure the structure with
Kevlar thread. Attach landing gear to fuselage with Kevlar
thread.
TAIL SURFACES
Lay out and glue parts of the tail surfaces on the plans.
Sand the tail parts, rounding off all edges. Don’t add the
horns or hinge the surfaces until after covering is complete.
DUMMY MOTOR
Assemble the dummy motor from the balsa parts supplied
and sand to shape. Not all the parts of the engine are
supplied as some are best fabricated from other materials.
Solid 16 gauge copper electrical wire (black insulated)
makes an excellent “radiator hose”.

Albatros CIII 38”
Copyright© 2004-11 M.K. Bengtson All Rights Reserved Rev 07/11
COVERING
Any lightweight covering material can be used. Polyspan
makes a good choice, Litespan is also popular. Robert
Stinson used Solartex.
Downloadable decal outlines are being developed. Check
on-line at http://www.aerodromerc.com/decals.htm to see if
one is available for this model.
WHEELS
Gluing the ply sides on the ¼ “balsa core makes the basis
for the wheels. Use the brass hub for alignment. Epoxy the
hubs in place and add a sufficient amount of epoxy around
the base of the hub to reinforce the connection of the hub to
the ply. Plywood reinforcing hubs are provided that are to
slip over the brass tubing as shown. Alternatively, gluing an
additional ½” square piece of scrap 1/8” balsa with a hole
drilled in the center can be substituted. Next, CA glue the
neoprene cording together to from a “tire”. Use thin CA
sparingly as the CA bonds very aggressively to the rubber.
Press the CA wetted ends together for an instant bond. The
best way to align the ends is to glue them while they are in
place on the wheel. Then attach the tires to the wheels and
CA in place. A thin bead of CA around the rim makes for a
secure tire.
Paper cones are cut out. Use a ball point pen to score each
line on the back to make an impression of “spokes”. It is
helpful to do this operation on a paper tablet so that the pen
makes a good crease. Fold the paper along the crease lines
to exaggerate the raised lines. One of the sections forming
a wedge is cut out. Make cuts to the center of the circle
along a pair of the spokes. Close the paper cut-out to form a
cone and tape the joint inside the cone.
The inside cones may now be attached to the wheels. The
outside cones may be attached at this point if wheel collars
are to be used. Alternatively, after installing the wheels on
the landing gear, a washer may be soldered to hold the
wheel in place and then the cone is attached. This method
makes a very nice scale appearance.
INSTALLING THE RADIO CONTROL GEAR
Servo Bay
It is as well to get the bulk of your R/C gear fitted at this
stage, and also the motor.
The cockpit combing is rubber fuel tubing, split and held in
place by friction.
Aileron Servos
Aileron servos are mounted in wing and attached with short
threaded rods to the ailerons. Use a “Y” wiring harness
connector to wire the servos to a single radio connection. If
differential aileron throws are desired, rotate each servo horn
aft about 20 degrees, while maintaining the neutral position
of the aileron. This should counter any adverse aileron yaw.
It is a tight fit but the HS-50's fit fine.
Battery Tray
After all the above has been placed, mount the battery tray
made from 1/8” balsa and use the battery position to balance
the model as shown on the plan.

Albatros CIII 38”
Copyright© 2004-11 M.K. Bengtson All Rights Reserved Rev 07/11
ASSEMBLY
Wing
Using Spars And Aligning Wing Panels
The first task is to epoxy the lower wings accurately onto the
fuselage. Use 5-minute epoxy for this task. Apply epoxy to
the wing rib that meets the fuselage. Attach the wings to the
fuselage. Use the locating spars to assist with aligning the
wing panels. Allow epoxy to set.
After the lower wings are attached, the struts are inserted.
Use thin CA to strengthen the laser cut ply cabane struts.
These provide attachment points to be epoxied into hard
bass blocks in the top wings. The top wing is added and
epoxied in place.
Fitting Tail Surfaces
The horizontal stabilizer is in two halves and has tabs that fit
into slots in the side of the fuselage. Insert the two halves,
and dry fit the elevator using CA hinges. The elevator
serves as an alignment tool so that the horizontal stab can
be CA glued in place. The vertical stabilizer also fits into a
slot in the top of the fuselage formed in F11.
Adding Detail Of Control Horns On The Pushrod Ends
Slip the control horns onto the wire pushrod ends and, with
both the servos and the control surfaces centered, glue the
horns into their slots.
Fitting the Guy Wires
Use strong thread or Kevlar fishing line or elastic beading
cording to simulate rigging wires. Use small screws, fishing
hook eyes, straight pinheads or small eyelets to attach the
lines. While not technically required these wires can add a
degree of strength to your model.
Windsock Datafiles “Albatros CII/CIII “ publication has details
on placement and markings. Available at:
http://www.aeroplanebooks.com/
Battery Hatch
Fashion a battery hatch from 1/32” plywood
Balancing The Model
Balance the model at the point shown. It is best to position
the battery to do this operation.
FLYING
Robert posted this on Ezone's Scale Modelling discussion
forum:
“The Albatros flew successfully today! You can now
advertise the plane "as flown in the San Diego Mid-Winter
Electrics" meet. (2003)
Otherwise, the power is quite satisfactory for scale flying
without being feeble. That's with a 3:1 gearbox, 9x6 prop,
Speed 400 motor and an 8-cell KAN 950 battery pack. As
you can see, it can be given a more powerful prop if desired.
The relatively small rudder (compared to non-scale, r/c'ified
planes) means that one has to be careful of ground loops
until up to speed. After trying some gradual accelerations
unsuccessfully, I just gave it max throttle; it scooted along,
picked up speed and behaved itself.
It is going to need some trimming. The right top wing didn't
accept the washout warp during construction. I think the
strut moved while the glue was drying. I'll have to fix that.
Once I trimmed the ailerons to counteract the roll tendency,
it tracked quite well in the sky, and landed kissing soft at a
nice sedate speed. I didn't try any stall tests, because of the
trim issue. I'll wait until a quieter weekend to test its
envelope further.
Bottom line? A beautiful kit, that flies very nicely. I give it two
thumbs up! Saluda! “
The model should ROG on pavement or hard surfaces. On
grass, the model may require hand launching. Be careful
that your hand or fingers do not catch on the lower rigging.
Launch firmly and level.
The tail surfaces should not need excessive throws. Let the
model gain altitude slowly off the runway. Applying too
much up elevator at slow speeds risks a stall. Make your
turns gently as tight turns risk tip stalling in any model. Don’t
expect the elevator to make the model climb. Think of the
elevator as a device to change the attitude of the model.
The wing and airspeed ultimately make the model climb.
Often down elevator applied at stalling can avoid a major
crash. The most important details for proper flight
operations are:
1) CG location. Tail-heavy models never fly well or at all.
2) Down and right thrust
3) Straight and non-warped wings.
CONTACT INFORMATION
Distributed by:
Bengtson Company
e-mail: [email protected]
Web Site: www.aerodromerc.com