Hi Branwell,

Reading your 3-D page I noticed the article on stationary spins. I have three
very different types of planes which can execute this maneuver, but the
required methods, are varying widely. I'm outside the size envelope for GSAL,
but from a technique point of view, it's in parity with the big birds. The
motivation for the three case studies is, that they, in addition to the one
you wrote, cover a great spectrum of techniques required to fly the maneuver.

1. Profiles (Morris Hobbies' Giant and 40-size Su-Do-Khoi) require full left
(or right depending on rotational preferences) rudder and aileron at the point
of stall. Full up elevator and, when rotation is established, feed full
power, and slowly, opposite aileron -- and we have a climbing flat spin. In
order to make the spin stationary, or control ascend and descend, just feed
less or more opposite aileron. Inverted spin is established in an identical
manner, with the given exception of stall inverted, feed down elevator, rudder
of choice, and opposite aileron. When rotation is established, cross the
aileron stick over after full power is applied. Thrust to weight is around
1.5:1 (Rossi 45. and 4.2 LB overall weight)

The profiles are climbing better and more controlled, by modifying the wing
vortex. Simply adding a tri-stock of balsa a several inches out from the
fuse, attached to the front of the leading edge covering slightly less than
half the wing span, provides a truer climbing spin.

2. My 3-D modified MW Extra 300S (thanks for the lightening tips by the way)
can only climb inverted, I assume due to the rudder being in cleaner air than
upright for improved yaw control. The spin is established by an inverted
stall, rudder of choice, opposite aileron and down elevator. Then, feed
ailerons (move in the same direction as rudder) until full, feed power and
slowly release the rudder stick until 1/4 only (approximately 10 degrees
throw) -- and the spin is climbing! To control ascend / descend just feed
less! rudder for climbs and more! rudder for descend. Thrust to weight is
around 1.5:1 (Moki 1.8 and 12 LB overall weight). Wing vortex modifications
were tried on the Extra, but no improved flight characteristics were
experience.

3. Goldberg Ultimate - power by Moki 1.8, having endured several 3-D
modifications: 1) the moving portions of the horizontal and vertical
stabilizers are enlarged with control throws at around +/- 45 degrees, and 2)
enlarged "cheater struts" between the wings. To conform to IMAA, I extended
also the wing to 62". The Ultimate is probably the most difficult of the
three planes to fly stationary spins, but here she goes: Establish flat spin
upright as previously described, by stall, rudder, aileron and up elevator,
slowly release! elevator to a third up only, and feed in up to 1/2 power. The
difficulty is to use sufficient -- but not too much -- power and elevator
since too much will cause an immediate tumble or waterfall with rotation.

On a side note, the Ultimate has by far the best transition characteristics
between flying on the wing to flying on the prop. It allows superior control
while driving in hover. I cannot drive my Extra, and the profiles have a
tendency to fall out at too low of an angle of attack. Thanks to the swept
wing, the elevators are very clean and stable, so waterfalls require no
adjustments in yaw or roll, even at full power. Thrust to weight is around
2:1 (Moki 1.8 and 9 lb.)


Best Regards,

Happy, safe, tumbling flying


Anders Hoberg