Why are (some) delta wings stable without a horizontal tail?

"Dudley Henriques" wrote in message
k.net...

"xerj" wrote in message
...
Thanks Dudley.

Make sense now.
No sweat. Darrell hit on some of the operational issues for you. Also in
fighters like the 106 and the Mirage, you could grab a yard of stick above
corner, rotate the lift vector, and bleed the Ps down with the drag curve
so fast that overshoot became a real issue for a shooter sitting on a
tracking solution.
It was Lippitsch I think who pioneered the delta without a tail. The idea
was popular for a while, but the extremely high landing speeds made
handling the airplane a real challenge. The whole deal centered around the
trailing edge design. Putting the horizontal stab back on the airplane
(Mig 21/blown flaps etc) helped the low speed/angle of attack situation on
landings, but the delta remains even today as a huge induced drag machine
into the left side of the envelope.
Power control and front side/back side power curve issues on final are
still major areas of concern for the deltas.
Darrell knows......that arrowhead of an airplane he flew was one hell of a
piece of equipment :-))
Dudley Henriques

Yeah, Dudley, I was an instructor in the TB-58 towards the end and we
demonstrated high sink to the new pilots. We'd slow well below approach
speed in level flight and raise the nose to stay level. We'd slowly add
power up to 100% but stay out of afterburners. Pretty soon we'd hit high
drag/high sink and I'd have the student note his vertical speed. We
"looked" level but were descending at nearly 4,000 FPM. He could still
change the pitch and roll with apparently normal response but he couldn't
stop sinking until he could increase the speed. We practiced at medium
altitudes where you could lower the nose, accelerate and fly out of the
danger area. The main point of the exercise was to show how important it
was during approach to landing to keep the speed within normal boundaries.
On final approach there's not enough altitude to lower the nose and fly out
of it. If you ever got into high sink on final you'd have to light all
four afterburners and hope they all lit off. If one didn't light at that
very low speed you'd not have enough control to handle it. Especially if
it was an outboard engine that didn't light off.