Incidences
As a datum line for checking/setting all incidences you can use the fibreglass side rails of the
cockpit opening, which are at 0 degrees.
The nominal incidence for both the top and bottom wings is 0° degrees, and this has been
proven to be the best set-up after many flights with the 2 prototypes.
The stabiliser incidence is +1.5 degrees, and this is pre-set in the moulds.
The wings and stabs have been fitted to the fuselage at the factory to check these incidences.
If you should find that the tips of the bottom wing have a little bit of positive incidence (0.25 -
0.5°) you will need to pack the front edges of the outer struts a little. Be careful when tension-
ing the Flying wires as this can also twist the wings a little and adjust the incidences.
The engine firewall is also set in the moulds, nominally at 0° up/downthrust, and 2° degrees
right sidethrust.
If you want to have the most ‘neutral’ setting, you can reflex the ailerons on the lower wing
‘UP’ by about 6 - 8mm (1/4 - 3/8”). Since all the ailerons are independent from each other you
can adjust this setting flight-by-flight to your personal preference.
Cowling
The lower cowling is secured to the fuselage with fourteen M3 x12mm bolts, washers and blind
nuts, spaced evenly at about 100mm. The blind nuts are fitted inside the upper cowling,
reversed,
with the spikes pointing inwards. Rough up the inner surface of the upper cowling
first, fit the blind nuts in place with a drop of CA, and when all are positioned correctly secure
with some epoxy and microballoons mix.
You will need to make a ‘U’ shaped cutout in the back edge of the cowl for cooling, as shown
in photo P1. We made it 160mm wide and 170mm front to back - and this has proved ade-
quate even when flown in very high ambient temperatures.
We have also supplied 3 pieces of milled 3mm glassfibre/balsa in the kit to construct the
engine baffle for the DA-150. This improves the cooling considerably and should not be omit-
ted. Photos P31 and 32 should make the assembly clear. Paint flat black before gluing into
place.
Motor and pipe installation
Both prototypes were flown with a DA-150 motor, using a pair of Greve tuned pipes, and this is
quite adequate with a dry model weight of about 20 kg (44 Lbs).
The plywood firewall already has approx 2° degrees of right sidethrust /offset built into it, and 0°
downthrust. Fine tuning of the sidethrust and upthrust is set by using an incidence meter and
adding washers between the plywood firewall and the stand-offs in the usual manner.
If fitting the DA-150, draw a horizontal centerline on ply firewall, using the mould seams on the
sides of the motor dome as guides. Draw a vertical centreline, and offset the engine mounting
holes 40mm either side, and 45mm top and bottom. (the DA-150 has 90mm vertical and 80mm
Composite-ARF Pitts S12
12