following was submitted by Frank Baldwin (N70FB):
"I will discuss the basic normal upright, as opposed
to inverted, spin for your interest. The Boredom Fighter when operated in the normal
CG limits has very pleasant positive entry and recovery spin characteristics. I
speak of N70FB and in regard to my aircraft I have made a slight modification to the
rudder. Last year I built a new rudder for esthetics, slightly increasing the area and
decreasing the gap by 1/4 inch. The spin entry and recovery has been improved. This
slight change improved the rudder effectiveness just enough to notice.
Since we are exploring an unknown
area be sure the CG is at the forward limit for more positive recovery. A climb to
an altitude at least 3000 to 5000 AGL is recommended.
The basic stall, spin technique is
to slow about one knot per second with the power at idle and carburetor heat on. As
the aircraft stalls, gently but firmly apply full rudder in the direction you wish to spin
and gently but firmly apply full aft stick keeping the ailerons neutral. Since the
biplane has high drag this will cause a more rapid speed reduction. Be sure to have
the pitch attitude 12 to 15 degrees nose up and you will find with the proper control
inputs this aircraft will gently enter the spin with the nose well down. Since we
are testing for unknown spin characteristics start the spin recovery at the half turn
incipient spin phase. Many aircraft can recover from this incipient spin phase, but may
not be able to recover from a steady state spin. Since I am not a professional test
pilot, I have limited my spins to one turn.
Normal spin recovery technique is
to apply full rudder opposite to the direction of yaw. Next move the control stick
smoothly but firmly forward until the rotation stops. Quickly centralize the rudder
and ease out of the dive. Do not pull up too rapidly, as you may exceed the
structural limits of your aircraft and stall again. My B. Fighter recovers positively in
less than 1/4 turn. Recover from the first deliberate spin after half a turn.
Proceed with spin tests by extending the spin 1/4 turn until you have reached one
full turn. If your aircraft is not built for aerobatics, no further spin testing is
required or recommended. My B. Fighter recovers from a one turn spin in 400 feet and
checking the recording G-Meter after a recent series shows a moderate 2.7 G reading.
Application of power increases the
difficulty of spin recovery. In case you spin and power is inadvertently applied
observe the first basic rule for spin recovery: "CUT THE THROTTLE."
Designer Don Wolf said of the
prototype "it will not always spin" and I found that also true with my aircraft
and its original rudder. With the new rudder, it will spin nicely on demand. I
would advise that the rudder to fin gap be kept to a minimum and do not decrease the
rudder size. Since this is not primarily an aerobatic aircraft the rudder
effectiveness as designed is more than adequate.
After all the cautions above you
wish to solve the problem as some manufactures have. You may prefer to simply
placard your aircraft , "SPINS PROHIBITED."