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Composite-ARF Extra 330L (2.3m span)
Finally glue the 4 blind nuts to the inside of the firewall and
fix in place with a little 30 minute epoxy.
Adjustments to sidethrust after the first flights, if needed,
can be made by adding or removing washers between the
back of the engine mount and the firewall. In the future we
hope to add the mounting hole dimensions for other popu-
lar motors to these instructions, or on the website.
Throttle servo: Make up the throttle servo mount, as
shown, from the milled plywood parts supplied, and glue
the mount onto the baseplate with 30 minute epoxy and
milled-fibre mix. It is your choice where to mount it, but we
do not recommend that you mount it on the back of the fire-
wall (as shown in a couple of these original photos)
because the engine vibrations can 'kill' the servo quickly. A
good position is on the side of the fuel tank mount, but the
long linkage must be properly supported. The M3 threaded
rod, nuts and clevises for the linkage are supplied in the
hardware pack.
All DA motors need quite a lot of servo throw to get the full
throttle range, so make sure you can fit a long output arm
on the servo, and allow for this when cutting the clearance
hole in the firewall for the linkage.
Standard Mufflers: If you are using a standard muffler just
mount it onto the engine and check if you need to cut clear-
ance holes in the bottom of the cowl for the exhaust outlets.
Mini - Pipes: An internal mini pipe installation is a little
more complicated than the use of standard mufflers, but
sometimes you don't have any choice, especially if you
have noise problems at your club field. In Europe noise is
always a problem, so Composite-ARF had to find a quiet
and powerful solution, and we recommend the MTW short
mini pipes with the headers as shown in this installation.
They come complete with teflon joiners and swage clamps
and this package can be ordered from Composite-ARF as
an option. This set-up gives the engine a nice throttle
response, a perfect mid-range, and also increases the top
end power slightly.
The main plywood bulkhead in front of the landing gear
already has the 2 semi-circular cut-outs for the twin mini-pipe system, so installation is quite
easy. Mount the 2 headers to the motor and use these to find the approx. locations of the cut-
outs needed in the bottom of the motor dome. Mill these in the motor dome for the mini-pipes.
Keep them small at this time, and enlarge them later for a perfect fit and sufficient cooling. We
recommend that you make the holes in the lower firewall at least 12mm (1/2") bigger than the
diameter of the mufflers to allow enough cooling air flow. C-ARF advise that you do not cut
through the central vertical 50mm (2") wide carbon joining tape between the 2 headers.
techsupport@composite-arf.com
(above) We highly recommend the
MTW mini-pipes, headers and
teflon connectors, which C-ARF
can supply as an option. Also seen
here is the steel strip, bent to the
shape of the 2 mufflers.
The Throttle servo mount is assem-
bled from the milled plywood
parts, and positioned on the side
of the fuel tank plate, or in your
chosen position.
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