Supermarine Sparrow I 36” User manual

Supermarine Sparrow I 36”
Copyright 2004 Rev 10/04
Supermarine Sparrow I 36”
R/C Scale Model Instructions
CONTACT INFORMATION
The Supermarine Sparrow I was designed by
Kurt Bengtson
Prototype Builder Mike Stanley
Manufactured and Distributed by:
Bengtson Company
PO Box 51102
Pacific Grove CA 93950
Phone: [phone]
Fax: [phone]
e-mail: [email protected]
Web Site: www.aerodromerc.com
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Supermarine Sparrow I 36”
Copyright 2004 Rev 10/04
Sparrow I 36”
Thank you for purchasing the Sparrow I model for
electric flight.
The new Supermarine Sparrow I was entered into the
1924 Daily Mail Two-Seater Light Aeroplane
Competition held in Lympne, Kent UK. The sparrow
was flown by Henri Baird on September 11. It's color
scheme included a dark blue fuselage bearing the
number 9 on an aluminum doped background. The
wings, struts, tail surfaces and engine cowling were also
an aluminum doped color. The aircraft sported full-span
ailerons on both wings. They could be drooped to
modify the camber of the wings in a flaps like fashion.
The Sparrow was plagued by chronic engine failures
and did not win the competition. In fact, it required a
second engine to finish the race and even that one
seized up on the approach to the finish line. Still, the
airframe is a classic and refitted as an electric flying
model, she is a delight to fly.
Aircraft Specifications
Manufacturer: Supermarine Aviation Works LTD
Entered Service: 1924
Number Built: 1
Engine(s): 35 hp Blackburne Thrush
Wing Span: 33ft 4 in.
Length: 23 ft 6 in.
Height: 7ft 5 in
Empty Weight: 475 lbs
Gross Weight: 860 lbs
Max Speed: 72 mph
Crew: 2
THE MODEL
A semi scale adaptation, this model is designed to be
easy to build and exciting to fly.
Model Specifications:
Wingspan: 36"
Weight: without battery is 10 oz. 16 oz with
8x1050 Kan nimh
Power
system: Designed for Speed 300 Horst 4:1 gearbox.
Micro servos Rudder and Elevator,
pushrod connectors.
Balsa and Litespan , Polyspan or Clearfilm
covering
Wheels: Balsa, plywood, Neoprene foam cord tires,
Brass tube hubs Paper card wheel cones
BUILDING THE MODEL
FUSELAGE CONSTRUCTION
The fuselage is built as a unitized box structure, using
pre-cut side frames with pre-cut notches for the formers.
Building Of The Fuselage
Begin by connecting the fuselage frames and formers
over the top view of the fuse on the plan. Crack the
fuse sides as indicated by the marking on the fuse.
Lean them in and glue in the horizontal the motor mount
FT.
Add slight right thrust by trimming the right side of the
fuse before attaching F1 and the front balsa nose.
Down thrust is built into the Horst Gearbox.
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Supermarine Sparrow I 36”
Copyright 2004 Rev 10/04
Adding The Undercarriage Plates
Once dry, remove from the board and add the 1/8” x1/4”
bass wood crosspieces that serve as u/c plates.
Stringers and Sanding
Add the top stringers before giving the fuselage a good
overall sanding.
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.
WINGS
Wing Construction
Pin down, over the plan, the t/e, l/e, spar and wing tip,
gluing as required. Making sure that you are using the
correct ribs for the wing you are building, glue all but the
center ribs in place. With one panel on the building
board, raise the other wing panel to allow for dihedral.
Mount the dihedral brace in place and glue. Sand the
leading edge stock to be rounded and meet the ribs.
Completed top wing half.
The Center section with dihedral brace.
Adding dihedral.
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Supermarine Sparrow I 36”
Copyright 2004 Rev 10/04
Lower wing rib dihedral adjustment.
COVERING
Any lightweight covering material can be used.
Polyspan makes a good choice Litespan is also popular.
The Prototype was covered with Solite.
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 shown on the plan are cut out. Use a
ballpoint 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 his 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, but NOT the battery pack.
Mounting Motor, Radio Location And Electronic
Speed Control
The motor mounts should be placed as shown in the
plan for proper right and down thrust.
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Supermarine Sparrow I 36”
Copyright 2004 Rev 10/04
Battery Tray
After all the above has been placed, mount the battery
tray and use the battery position to balance the model
as shown.
ASSEMBLY
Wing
The lower wings are epoxied in place first propping their
wing tips up by the appropriate amount for dihedral.
The top wing is attached using 1/8” cowl cabane struts
and Bass “N “ wing struts.
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.
Undercarriage
Bind and cyano the u/c legs in place and bind and
solder them to the axle. Alternately, Kevlar thread and
CA glue also work well.
Fit The Access Hatch
Fit the access hatch; add the battery pack and your
model is finished.
Balancing The Model
Balance the model at the point shown. It is best to
position the battery to do this operation.
FLYING
Mike Stanley the prototype builder, reports: ”The
Sparrow is a beauty to fly, first flight was ROG from
asphalt as soon as you apply power the tail comes up
and it rolls perfectly straight on it wheels for about 8 to
10 feet before it lifts itself (no up elevator required) up
off the runway. I needed 2 clicks of right trim and off we
went. After a slow steady climb to about 60 feet gave
her full throttle and pointed her straight up until stall
(probably around 120 to 150 feet) she dropped over to
the left and the nose pointed straight down, the plane
fell about 8 feet and straightened out on its own.
Loops are very comfortable from level flight and
predictable, half to a quarter throttle flying is no problem
using 8 cell Kan 1050mah and a castle creations Pixie-
P20. Left and right turns are very flat causing me to
apply a little up elevator even when it wasn't needed.
With the speed 300 and 4:1 gearbox you can slow the
plane down then turn hard left then let loose of the left
stick (the motor rotation direction) while applying full
throttle and she will torque roll one time then straighten
out, a product of 8 cells I would say.
I'm using 50% throws on my JR Radio which works out
to about 3/8" both direction for the rudder and using
40% throws for the down elevator (1/4") with 60% up
elevator (1/2"). I'm a thumb flyer and always fly within
1/8" of center on the sticks (very light handed) if that
makes since. Also on 8 Kan 1050mah 12 to 15 minutes
of regular flying. After climbing to a safe altitude and
cutting off the motor the plane has a very slow and
predictable rate of glide.”
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. (3/8” of
washout is OK to put into the wing tips)
4. Be sure you assemble and lube the gearbox so
that it is not binding. A binding gearbox will rob
most of your batteries power.
CONTACT INFORMATION
The Sparrow I was designed by Kurt Bengtson
Distributed by:
Bengtson Company
PO Box 51102
Pacific Grove CA 93950
Phone: [phone]
Fax: [phone]
e-mail: [email protected]
Web Site: www.aerodromerc.com
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