the fuselage and will be connected to a separate battery pack,
used to power the system.
The most convenient location for this module in our Rascal 110
installation was at the lower right corner of the fuselage, just
behind the firewall. We opened an oblong hole in the firewall at
this location to route the wiring through to the engine. The ignition
module is wrapped tightly in foam and wedged in place against the
firewall, inside the nose.
❑
6) The engine, with the muffler in place, should now be ready
to mount, using your own hardware. We suggest using hardened
steel socket head bolts of the correct length with lock washers. In
the case of our F.P.E. 1.3 engine, we used four 8-32 x 1-11/16"
bolts. The bolts must be long enough to go through the blind
mounting nuts, but no further. The bolt ends must not contact the
fuel tank body. If your bolts are too long, use a carbide cut-off
wheel to shorten them to the correct length. Mount the engine to
the firewall, but do not tighten the bolts yet.
❑
7) The throttle linkage is now assembled and installed. With
gas engines, it is especially important to avoid any metal-to-metal
connections.
This is because such connections may cause
unwanted RF (radio frequency) "noise".
Such RF noise can
interfere with the radio system. It is, therefore, important to use the
provided nylon pushrod, with a nylon fitting at the engine's throttle
arm. For this throttle arm connection, we recommend using a
Du-Bro #181 2-56 Threaded Ball Link. This package contains
everything needed to make the proper throttle pushrod connection
to the engine. Most gas engines used for R/C model aircraft, are
equipped with Walbro carburetors and most of these engines
have the carburetor mounted to the side of the cylinder head, at
non-linear angles. The ball-link throttle arm connection solves this
problem.
If the throttle arm on your engine is spring loaded, either remove
the spring or cut it from the throttle arm with wire cutters. Choose
a location on the throttle arm that will best provide fore and aft
linear movement from the servo. This is the location to mount the
ball link fitting. Drill the throttle arm to accept the ball link and
mount it in place.
Note that some throttle arm locations and
shapes may require an extension that must first be attached to the
primary carburetor throttle arm. If this is the case with your engine,
make and attach the extension with the ball link fitting in place.
Use a pencil to mark the firewall at the point where the throttle
pushrod will be placed. Remove the engine from the firewall and
use a 13/64" dia. drill bit to make a hole through the firewall at the
mark just made. The nylon throttle pushrod housing tube is now
installed. To do this, follow the instructions provided in Step 12 in
the 4-Stroke Engine section to install this tube. After the outer
pushrod housing tube is in place, remount the engine permanently
in place to the firewall. Be sure to use thread lock compound on
the bolt threads. Attach the wiring leads to the engine.
❑
8) The inner nylon throttle pushrod is now prepared. Use a
carbide cut-off wheel to remove the 2-56 x 3/8” threaded section of
the Du-Bro brass coupler fitting. Chuck this threaded section into
your power drill, leaving half of its length exposed, and thread it
into one end of the nylon throttle tube. Thread the nylon ball link
fitting onto the remainder of the exposed threads.
Insert the opposite end of the nylon pushrod into the female tube
at the firewall and push it in place all the way back to the servo bay.
Press the nylon ball link fitting onto the ball link on the carburetor
throttle arm. The servo end of the pushrod will be prepared after
the throttle servo is installed in the coming steps.
❑
9) As mentioned earlier in the Fuel Tank Assembly steps, it is
very convenient to install a fueling valve in this airplane.
For
gasoline engines, Du-Bro makes a very good fueling valve, Du-Bro
P/N 335. This valve is easy to use and we have provided an
aluminum bracket in your kit that will allow you to mount the valve
directly to the firewall. In our gas powered Rascals, we mounted
this valve on the right side of the firewall. Connect the Tygon fuel
lines to the appropriate nipple fittings on the engine and it is ready
to use.
❑
10) Gas engines with ignition systems require a separate
battery pack to power the ignition module. In the case of our F.P.E.
1.3, we used the standard 4-cell 600maH battery pack that came
with our radio system for this purpose. This battery pack provides
about 1-1/2 hours of running time before needing recharging. We
mounted our ignition battery pack in the nose of fuselage, beneath
the fuel tank. We wrapped it in foam and wedged it firmly in place.
The ignition system must be able to be turned on and off as
needed and this means that there must be a separate switch for
this purpose. We used a standard radio system switch assembly,
with a charging receptacle, for this purpose. We mounted this
19
Ignition
Switch
Radio
Switch
