DeHavilland
DH88 Comet
INSTRUCTION MANUAL
A semi scale ARF R/C
model of the famous
winner of the 1934
MacRobertson, England
to Australia Air Race.
Wingspan: 88 inches (2235 mm)
Length: 59 inches (1500 mm)
Engine/
2 x .32~.40 2 stroke
Motor:
2 x .52 4 stroke
2 x brushless electric motors
Radio: 5 or 6 channel
DeHavilland
DH88 Comet
Histor
y of the DeHavilland DH88 Comet
The original DeHavilland DH 88 ‘Comet’ was specially designed to compete in the 1934 England to Australia
MacRobertson Air Race. Three were designed, built and tested in eight months with the first flying on the 8th
September 1934.
The all wood aircraft was powered by two special DH Gypsy Six R engines producing 230 h.p each. The
Comet was the first British air
craft with r
etractable landing gear
, flaps and contr
ollable pr
opellers.
Sponsor
ed by Australian MacPherson Robertson, the MacRobertson Air Race was the longest ever Air Race
from Mildenhall in England to Melbourne, Australia with the winner receiving 10,000 English pounds.
Piloted by Charles Scott and Tom Black, the winning aircraft GACSS (named Grosvenor House after its
sponsor
, a luxury hotel in London) won the race in 70 hours and 54 minutes.
Wingspan - 44ft (13.41m)
• Wing Ar
ea - 212sq.ft. (16.69m
2
) • Length - 29ft (8.84m) • Height - 10ft (3.05m)
• Empty Weight - 2,840lb (1,288kg) • Max Takeoff Weight - 5,320lb (2,413kg) • Fuel Capacity - 258 gal
• Engines - 2 x 230 h.p. DH Gypsy R • Cruising Speed - 220mph (354km/h)
• Maximum Speed - 237mph (381km/h) • Service Ceiling 19,000ft (5,790m) • Range 2,925 miles (4,707km)
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Safety Warning:
This R/C aircraft is not a toy. Serious injury or damage to property can result through misuse and abuse. It
is recommended that this aircraft is flown at a dedicated R/C flying site and that a qualified instructor
thoroughly checks over the model before its first flight.
Your local model shop should be able to assist you r
egarding flying clubs in your area.
Additional Items Required to Complete the DH88 Comet:
• 2 x Metal geared micro servos for aileron control
•
3 x Standard size high torque servos for rudder, elevator and flap control
•
1 x Additional micro servo required if optional retractable landing gear is fitted
•
2 x Additional standard size servos required for glow engine power (throttles)
• 2 x Suitable ESCs for electric power version
• 5 and 30 Minute epoxy glue
• Medium and thin CA adhesive
• Masking tape
•
2 x .32~.40 2 stroke engines & 10 x 6” to 11 x 7” props or
2 x .52 4 stroke engines & 10.5 x 8” to 12.5 x 6” props
(for i.c. version)
•
2 x 36-30-2/1500 RP/V motors & 8” x 5” props or
2 x 36-30-3/1000 RP/V motors & 10” x 5”~6” props
(for electric version)
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STEP 1:
Trial fit the tailplane to the fuselage and mark where
the area of covering will need to be removed to
expose the wood and enable the glue to adhere
p
roperly. Carefully cut through the film covering
inside the marks - ensuring that you do not cut into
the wood sheeting.
STEP 2:
Make a groove in the tailplane for the
pre-assembled elevator joiner/control
horn to rest.
STEP 3:
Using a sharp knife or a
round file, make a small
notch in the fuselage to
clear the elevator joiner
and the rudder/tailwheel
assembly
.
STEP 4:
Connect the elevator
pushrod to the elevator
joiner/contr
ol hor
n and
fit into position in the
fuselage.
STEP 5:
Connect the rudder/tailwheel pull/pull
cables to the assembly then slide the
tailplane in position. Before gluing the
tailplane in position, make sure that is
corr
ectly aligned in relation to the wing.
STEP 6:
Now run a small bead of
medium CA ar
ound the
outside tailplane/fuselage
joint. This will prevent glue
running onto the tailplane
covering when applying
medium CA adhesive to the
inner joint.
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STEP 7:
Using 5 minute epoxy, secure the vertical fin in
position making sure that it is square in relation to
the tailplane. After the epoxy has set, run a bead of
m
edium CA around the outer joint.
STEP 8:
Using the supplied hinges, fit
the elevators and rudder in
place by applying a few
drops of thin CA adhesive to
both side of the hinge.
STEP 10:
Then fit the ailer
on servos to the
removable hatches with some
double side foam tape. For
extra security we would suggest
fitting additional hardwood
mounting blocks.
STEP 11:
Measure and mark the half way
point of the alloy wing joiner
tube.
Glue the alloy tube into one of
the wing panels. Only insert
tube up the half way point.
Let epoxy set thoroughly before moving to the next step.
STEP 9:
Feed aileron extension leads though the centre
wing panel. A hole approximately 16cm from the
leading edge will have to made in the center section
for the leads to exit.
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STEP 12:
Before glueing the outer
wing panel to the centre
section, apply masking tape
a
round the edges of the
panels to be joined to help
prevent glue running on to
the covering. Join the panels with 30 minute epoxy. Remove the
masking tape from the panels before the epoxy has set. Use
rubbing alcohol or methylated spirits to remove any epoxy residue.
STEP 13:
Secure the ailerons in place
with a few drops of thin CA
adhesive applied to both
sides of the hinges.
Fit the control horns to the
ailerons and assemble the pushrods from the supplied parts.
STEP 15:
The DH88 Comet is designed to
use either glow or electric power.
The supplied engine mounts ar
e
used for both glow and electric
power
.
STEP 16:
Fitting Glow Engines.
For glow engine power the
pr
e-assembled thr
ottle servo
mounts need to be installed alongside the fuel tanks in each of the
engine nacelles.
STEP 14:
Install the elevator and
rudder servos in the
plywood servo tray in the
fuselage.
Adjust the length of the
elevator pushrod and the rudder pull/pull cables and fit to the
appropriate servo.
Elevator
Servo
Rudder
Servo
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STEP 17:
Installing Electric Flight Batteries
T
he installation of electric flight
batteries will vary depending on the
battery type and size used.
The suggested mounting position
(for Li-Poly batteries) is under each
motor using Velcro straps. We recommend that hardwood rails be installed
in this area for added strength and security.
STEP 18:
The nacelles can now be fitted to the
centre section using the Allen headed
bolts supplied. You may wish to
apply a bead of silicon sealer to the
inside edge of the nacelle and, after
protecting the wing with tape, wipe
off any excess silicon as the nacelles
are bolted up to protect the wing surface from the nacelles rubbing.
STEP 19:
Fixed Landing Gear
Position the pre-assembled fixed
landing gear assembly in the slotted
hard wood mounting rails in the
engine nacelles.
Secur
e with the supplied landing
gear straps and scr
ews.
STEP 20:
Optional Retracting Landing Gear
The retractable gear units use the same mounting rails as the fixed
landing gear
.
Route the airlines so they exit through
the same hole as the servo leads.
The air tank, r
etract servo and valve
can all be neatly mounted on the wing
centre section. Secure with the
supplied landing gear straps and
scr
ews.
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STEP 22:
The receiver and receiver battery are
mounted on the pre-installed
plywood tray at the front of the
fuselage.
Secure the hatch with four of the
supplied small self tapping screws.
STEP 21:
The flaps are supplied pre-hinged and simply require a
suitable servo installing in the pre-cut well and a linkage
making. As the hinge line is not straight, we recommend
t
hat ball links are used. Check that the flaps operate
freely. They are suprisingly effective and offer a
reasonable braking effect during landing appproaches.
STEP 23:
Fit the tail wheel fairing using some
medium CA adhesive.
STEP 24:
Fit the engine nacelle fairings to the
wing using medium CA adhesive.
STEP 25:
Fit the clear nose cone and canopy
in position with the small screws
pr
ovided.
STEP 26 - Balancing the Model:
As with all air
craft it is imperative that the model balances at the
correct Centre of Gravity. The C.G. for the Comet is 115mm from
the leading edge measured at the fuselage side.
Note: if the optional retractable landing gear is fitted, balance the
model with the landing gear retracted.
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Guarantee
Advanced Scale Models guarantees this kit to be free from defects in both material and workmanship at the
date of purchase. This does not cover any component/parts damaged by use, misuse or modification. In no
case shall Advanced Scale Models’ liability exceed the original cost of the kit.
In that Advanced Scale Models has no control over the final assembly or the material used for final
assembly, no liability shall be assumed for any damage r
esulting from the use by the user of the final
user-assembled product. By the act of using the final user-assembled product, the user accepts all resulting
liability.
Distributed in the USA
by:
Global Hobby
18480 Bandilier Circle,
Fountain V
alley
,
CA 92708. USA.
Distributed in Eur
ope
by:
Ripmax Ltd.,
241 Green Street, Enfield,
EN3 7SJ. UK.
Distributed in Australia
by:
Model Engines (Aust.) Pty. Ltd.
Unit 1, 158-168 Browns Road,
Noble Park, VIC., 3174
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Flying Tips:
•
Retractable Landing Gear:
B
ecause the landing gear retracts rearwards there will be a change in the
aircraft’s trim. While the change in trim is small, it is noticeable and the pilot should be aware of this
characteristic.
• Use of Flaps: With the flaps lowered the Comet will ‘balloon’ upwards slightly and will require some down
elevator trim. It is recommended that when flaps are deployed for the first time, do this at a safe altitude
and re-trim accordingly.
• Torque Effect: Being a twin engined aircraft, and with no direct prop wash acting on the rudder, the torque
of the engines/motors has a greater effect during the initial part of the take off. The aircraft will veer left
and the pilot needs to be ready to correct this with right rudder input. The amount of rudder needed for
correction will decrease as speed increases.
• Landing: Do not attempt to slow the model drastically on landing. It is recommended that ‘wheel’ landings
be performed rather than ‘three point’ landings.
STEP 27 - Setting the Control Throws:
Aileron - 10 mm up/down
Elevator - 25 mm up/down
Rudder - 30 mm left/right
Flap - up to 40 degrees.
/
