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.

Hi Darrell;
Don't know if you got to the T38 or went through in the T-Bird, but what you
are describing isn't all that far off from what can happen to you in the 38.
Of course the Talon is a trapezoidal low aspect wing, but on final, if you
weren't careful, you could set up a sink that was unrecoverable. I've seen
6000 FPM on the VSI in the 38.
The Hustler must have come down like a brick with all that hardware hanging
under the wing :-)
Getting one of these high performance birds way back in the coffin corner
killed many an otherwise descent pilot.
I'm sure you remember that kid out at Edwards in the 100 who got into the
backside so deep he ended up in the corner and couldn't power out without
reducing the angle of attack and didn't have the room to generate any nose
rate in pitch at all. I'll bet I've seen that film clip a thousand times.
It's still the best lesson for keeping the final approach speed where it
belongs that I've ever seen.
I guess in the Hustler you went backside and into the left corner mighty
fast
:-))
Dudley


"Darrell S" wrote in message
news:Cqz_f.186$Oe2.34@fed1read07...

"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.

Getting one of these high performance birds way back in the coffin corner
killed many an otherwise descent pilot.

Doesn't a high sink rate sort of =define= a descent pilot?

Jose
--
The price of freedom is... well... freedom.
for Email, make the obvious change in the address.

"Jose" wrote in message
m...
Getting one of these high performance birds way back in the coffin corner
killed many an otherwise descent pilot.

Doesn't a high sink rate sort of =define= a descent pilot?

Jose

You know Jose, when you make a post like this to someone, you can go one of
two ways. You can stick a smilie on the end of it demonstrating the good
nature intended and make a friend, or you can just be a pedantic bore and
lose one. :-)
Dudley Henriques

You know Jose, when you make a post like this to someone, you can go one of
two ways. You can stick a smilie on the end of it demonstrating the good
nature intended and make a friend, or you can just be a pedantic bore and
lose one. :-)

Smilie intended.

Jose
--
The price of freedom is... well... freedom.
for Email, make the obvious change in the address.

"Jose" wrote in message
m...
You know Jose, when you make a post like this to someone, you can go one
of two ways. You can stick a smilie on the end of it demonstrating the
good nature intended and make a friend, or you can just be a pedantic
bore and lose one. :-)

Smilie intended.

Jose

Fair enough. Take care

DH

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

"Jose" wrote in message m...
You know Jose, when you make a post like this to someone, you can go one of two ways. You can stick a smilie on the
end of it demonstrating the good nature intended and make a friend, or you can just be a pedantic bore and lose one.
:-)

Smilie intended.

Jose

Fair enough. Take care

DH


I think Sean Tucker was a descent pilot last week... ;-)