When the propulsion
force is applied at the rear of a vehicle, it is destabilizing. The
slower the forward speed, and the higher the thrust-to-weight ratio, the
more problematic this effect is. A high powered model jet during the
early stages of taking off is exemplary of this phenomena.
The Proper Technique
A narrow, paved runway
that has obstructions on the sides requires the best techniques. The
first flights should be made in light wind conditions and preferably little
or no crosswind. With good piloting techniques, most jets will handle
a 10-15mph crosswind, but save that for later.
Set the wing flaps to
the take-off position and taxi into the take-off position on the centerline
and nose into the wind. Apply about 1/2 up elevator, release the
brakes and slowly advance the throttle to about the 1/2 position.
Direction control is primary, first with nose gear steering, and then as the
speed increases, the primary control is with the rudder. Once the
rudder authority is dominate and the model is headed straight down
the runway, advance the throttle to full power. The model will lift
off when it has sufficient airspeed.
Retract the gear and
climb to a safe altitude and then retract the flaps.
For the first flight,
keep the airspeed at a medium level and concentrate on trimming the model
and deciding whether or not the center of gravity is optimum.
The published C.G.'s
for BVMJets is on the conservative side - a place to start. You may
want to ease it back on subsequent flights.