To save weight in the 3W powered plane, we chose two 5-cell (AA-sized) 1400 mAH packs - and
these were both fixed inside the front of the motor dome. No additional lead was required to
achieve the correct Centre of Gravity. All battery packs should be wrapped in foam to isolate the
soldered connections from vibration as much as possible.
Receiver
We 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. In the DA-100 version it was
secured to the side of the fuselage, close to the angled plate behind the rudder servo mount
which was used to locate the Powerbox.
In the 3W version, to get everything as far forward as possible, we positioned the Powerbox
Evolution and the Receiver on a balsa-composite plate, glued to the top of the wing tube sleeve
- on the right 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 by gluing a plywood stick across 2 large holes in
the mounting plate - using 2 rubber bands around the Rx case. (see photo below)
RX Antenna
In both cases 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 -
and taped to the top of the fuselage. Secure it in short
lengths of silicone tube to make sure it cannot be cut
through by any sharp edges. 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 switch
included with the Powerbox Evolution is a ‘Fail-ON’ type, as
is the Powerbox ‘Sensor’ switch. We use the analog 20
Amp power-switches, also from powerbox, for the ignition
system.
If fitting the switches into the outside surface of the fuse-
lage, as shown, please reinforce the area inside with a
small patch of 3mm thick plywood to reduce vibration trans-
missions 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.
Servo Extension leads etc.
Please make sure that you use good quality twisted-cable
extension leads, of heavy gauge wire with gold-contact
connectors, to all the servos. Certainly we recommend that
all servo leads and extensions longer than about 30cms
(12”) are fitted with ceramic chokes (ferrite rings) to prevent
RF noise, at the receiver end - normally within 100mm (4”)
Composite-ARF Extra 300SX
(2.6m span)
31
6-pin MPX connectors are used for
extension leads, with one half
mounted in the fuselage sides.
(above) 3mm plywood reinforcing
plate glued inside the cutouts in
the fuselage sides for switches.