©2019 Moustache Model Works, LLC
37
20cc DHC
-
2 Beaver Instruction Manual
Control Throws and Programming
Elevator:
1”
(25mm) Up
3/4”
(19mm) Down
Ailerons:
1”
(25mm) Up
3/8”
(10mm) Down
Rudder:
1 1/4”
(32mm) Right and Left
Flaps:
~20° Mid
50°
-
60° Full
Flap
→
Elevator Mixing: Mid = 20%, Full = 30%
Aileron
→
Rudder Mixing: 35% Right and Left
Aileron Differential: 50%
These values are high
-
rate throws, select lower rates to taste. The first prototype is flown with high rates,
which provide a very comfortable level of control without being too sensitive to stick inputs. As of this writ-
ing, about two dozen pilots have flown the Beaver using these rates, and not one of them ever switched to
lower rates.
Aileron
→
Rudder Mixing is of course a matter of taste. You may want more or less depending on how
much rudder you want to input manually during turns.
Aileron differential, which means less downward throw than upward throw, is necessary to combat ad-
verse yaw. Adverse yaw means the airplane yaws the opposite direction of a roll input, even though it
rolls in the right direction. It
’
s caused when the drag of the lowered aileron is much higher than the drag of
the raised aileron. High aspect ratio wings with
“
barn door
”
ailerons traditionally exhibit significant adverse
yaw effects, and this Beaver is no exception. The impact is highly uncoordinated turns. Adverse yaw is
corrected by both aileron differential and aileron
→
rudder mixing, but aileron
→
rudder mixing can impact
aerobatic performance, especially during rolling maneuvers. Using a lot of aileron differential can help re-
duce the amount of mixing required, thus minimizing the impact to aerobatics. For this reason, we have
used both mechanical differential by angling the aileron servo horns forward, and electronic differential
through computer transmitter programming.
Flying
During takeoff, apply throttle slowly and smoothly. Hold a little up elevator from the beginning to keep the
tail wheel on the ground and maintain steering control until the rudder sees enough airspeed to become
effective, especially on pavement. Often this approach results in a three
-
point takeoff, as the Beaver
doesn
’
t need much airspeed to fly. With the Power 60, 400Kv on 6S, most takeoffs happen at 50% throt-
tle. We prefer using mid flaps for takeoff.
In the air, trim the elevator to maintain level flight at 50% throttle. This way she will gain altitude gently
when you increase throttle and lose altitude gently when you decrease throttle. The Beaver is very com-
fortable at that medium speed, which looks quite scale in the air.
Take her up to altitude and perform some stalls to get a feel for how she wants to behave. The first proto-
type is nearly impossible to stall at the forward CG location, while at the aft location, she will drop a wing
about 30%
-
40% of the time. Stall happens at a very low airspeed, and recovery is always fast, so even
the aft CG location has manageable handling qualities. With mid flaps, even at the aft CG location stall is
difficult to achieve.
The flaps are hugely effective, but require significant elevator mixing. When he flew it, Mike McConville
said mid flaps make it
“
buoyant,
”
which seems appropriate. At full flaps, she nearly stops in the air, mak-
ing super
-
slow landing the norm. Deploying full flaps in the middle of a loop or at the beginning of a split
-
S, then going right into a landing or even a crabbed landing is a blast.
For landing, use full flaps most of the time, or mid flaps if there is a lot of wind, especially crosswind. Both
wheel landings and three
-
point landings are appropriate.
