Flaps and V-Tails of Death

Earlier, JJ wrote:

I rolled in 45 degrees of flaps and
everything looked just about right.
Came over the fence at 50 knots and
waited for her to settle down...

If it's floating down the runway, you just don't have enough flaps
cranked in. Dick Schreder pointed this out when he wrote the
instructions on test flying the HP-11:

http://www.soaridaho.com/Schreder/HP...t_Testing.html

which says:

: If the HP-11 is floating down the
: runway and doesn't want to slow down,
: you just don't have enough flap
: cranked down.

That was in 1963, and I'm pretty sure that it still applies. The same
advice is also repeated in the test flight instructions for the HP-14
and HP-18.

When flying my HP-11 at Air Sailing when the wind favored 21 I
generally stopped right in front of the windmill near the
intersection. Just as I cross the edge of the sage along runway 17 I
would crank on the full 90, flare across 17, and come to a halt within
less than 100 yards of touchdown. And that's landing downhill in a
ship equipped with a go-kart style band-on-tire wheel brake.

The secret to the HP landing technique is to be proactive about
increasing stick forward pressure as you crank on the flaps. If you
try to be reactive, and wait until you see the airspeed change, you've
already gotten too slow. So the technique that works well is to get
the stick moving in the right direction as you crank the flaps on or
off, and worry about refining the speed control later. Control system
engineers call this a "feed forward" system, since there's just not
time to wait for feedback before starting corrective action.

As far as getting sucked into a cloud, the only time it happened to me
it was scary, but other than that rather tame. I cranked on about 75
degrees of flaps, put out the wheel to silence the warning buzzer, and
trundled out the bottom in a 45-degree dive at about 50 knots. The
important thing is to get the flaps out before you exceed the Vfe
speeds.

On another branch of this thread, Eric observes that one reason that
flaps are an issue is that there are so few two-seaters with 90-degree
flaps. I agree; this is one of the primary reasons that the next HP
kit will not be developed with 90-degree flaps. If anybody really
wants one, I can set the wings up for it, but the primary
configuration will have airbrakes. Personally, I really do prefer the
flaps over airbrakes. However, I do not have the resources to
prosecute an ideological battle on their behalf. If anybody wants to
know the depth to which I've sold out in pursuit of a successful
career as a sailplane developer, feel free to let this be the measure
of it.

Thanks, and best regards to all

Bob K.
http://www.hpaircraft.com/hp-24