the ignition system. The 4-cell pack for the DA-150 is secured inside the fuselage against the
front left side of the motor dome with cable-ties on a foam isolation pad.
Receiver Batteries
The prototype Yak is fitted with two 5 cell NiMH Rx packs of 2400mAH each, and a 4 cell
2400mAH ignition pack, and the ready-to-fly weight is just under 18.5 kg (40.5Lbs). If you chose
to use LiPo or Duralite packs the flying weight would reduce to about 18 kg.
There is absolutely no problem setting the correct CG on the Yak 3m, and you will see from the
photos that we fitted 1 Rx pack on the tank base, and the other to the back face of the muffler
compartment - both on foam pads and secured with cable-ties. These positions set the ‘pattern’
CG without any other weight adjustment.
Make sure that all batteries, and other heavy items, are very securely fixed in the plane - remem-
ber how much they will effectively weigh when subjected to 4 or 5 G’s!
Receiver
C-ARF strongly advise that you position the receiver as far
away from the high-voltage ignition unit as possible - at
least 200mm (8”) for the minimum interference risk. We
positioned the Powerbox Competition and the RX on the
balsa-composite plate on the left side of the tank base.
Please mount the sensitive Receiver on a rubber or foam
sheet, at least 3mm thick, to isolate it from vibrations. You
can easily secure the Rx either using 2 small cable-ties, or
by gluing a plywood stick across 2 large holes in the mount-
ing plate - using 2 rubber bands around the Rx case. (see
photo above)
RX Antenna
The Rx antenna was routed to the side of the fuselage,
then backwards along the fuselage side and out of the top
of the fuselage immediately behind the canopy - inserted
into a removable plastic tube. Keep it as far away as possi-
ble from the cables for the elevator servos and the closed-
loop rudder wires.
Switches
Often regarded as the ‘weakest-link’ in an R/C system, it is
very important to use quality switches for both
Receiver/Powerbox and motor ignition, and we only use
high quality switches from Power box. The electronic
‘Sensor’ switch included with the Powerbox Competition is
a ‘Fail-ON’ type, for additional safety. We use an analog 20
Amp power-switch, also from Powerbox, for the ignition
system.
If fitting the switches into the outside surface of the fuselage, as shown, you should reinforce the
area inside with a small patch of 3mm thick plywood to reduce vibrations transmitted to the
switches. It only adds a few grams. The Powerbox switches come with paper templates, making
it easy to cut the slots in the fuselage accurately.
Composite-ARF YAK 55SP
(3m span)
28
(above) PowerBox Switch mount-
ed in fuselage side, with ply rein-
forcement. Antenna wire and stab
extension cables are routed thru’
silicone protection sleeves and
fixed securely.
(below) Protect all wires and tubes
where they pass thru’ bulkheads,
or near sharp composite parts,
with a short length of silicone tube,
and cable-tie firmly in position.
