Glider vs. Power Pattern Bank Angle?

In article ,
Jim wrote:

I have experienced stall buffet at 60 degrees of bank in a thermal
in a DG-505, and I fly with a forward CG. Granted, stall buffet is
not yet a stall, and the DG's stall characteristics may be pretty
benign, but I no longer trust that a glider will be hard to stall in
steep turns.

I haven't flown a 505, but I've tried a DG-1000, and it has a *lot* of
available elevator power compared to most recent training gliders. The
thing can not only be held so deep into a stall that it will virtually
always drop one wing or the other, it can be flick rolled! (and the POH
permits that, with the 18m tips on)

But it gave so much notice that you were dicing with the stall that I
wouldn't be at all worried thermalling it slow.

-- Bruce

"Vaughn" wrote
that's what they teach their
students because they don't know anything else.

Actually there are many reasons, some of them may be found in the SEL PTS.

True. I oversimplified. Far be it from me to suggest that the FAA
isn't a big part of the problem - it is. Some of the stuff in the PTS
is garbage. It's getting better again, though. Real slow flight is
back - for several years, slow flight was redefined as 1.2 Vso. Steep
turns were redefined to 45 degrees and I see no hope of change there.
The 180 to a landing is back in the commercial PTS though, and that's
a plus.

Another is that airports with lots of light aircraft training end up
with huge "follow the leader" patterns.

Ah, yes - the "everybody is doing it" argument. Actually, I do
understand - sometimes the safest thing to do is just grit your teeth
and do it the same way everyone else does it. Only when I learned to
fly I was taught that when the pattern is strung out that way, you
hold your altitude until you reach power-off gliding distance of the
field, then reduce to idle and glide in.

Come to think of it, the FAA has changed landings since our trainers were
designed. Vaguely 20 years ago, there was a sea change in the way landing
technique was taught because someone in the FAA decided that normal landings
would be accomplished with full flaps.

Well, that makes sense to me. As far as I'm concerned, the normal
landing is made with full flaps. Anything less is a special case - a
reduced-workload training exercise for an early presolo student,
strong crosswind in an airplane where flaps reduce rudder/elevator
authority, that kind of deal. Otherwise, why accept the higher
touchdown speed with its attendant risks, extra wear on tires and
brakes, etc?

The normal technique that is taught
these days (at least in a Cezzna) is the first notch on downwind, second notch
on base and full flaps on final.

And there's the problem. What's wrong with a clean downwind, two
notches on base to adjust the glide, and then the rest on final when
it looks right? I was taught to land that way. In fact, I was taught
to land a Cessna by bringing the power to idle abeam the numbers and
adding flaps as necessary to control glideslope. Might have had
something to do with the fact that my primary instructor flew gliders
too...

This adds so much drag that you either do a
high (and or tight) pattern or you must drag the thing around the pattern with
power. Guess which one they usually teach?

Right - because that's all they know. They really don't know enough
about flying a tight high pattern to teach it.

In a multiengine turbine airplane, what they teach is actually the
right thing to do. Those engines take time to spool up, so you dirty
the plane up, keep the engines spooled up, and for a go-around you
clean up the plane - this way you can get a climb going before the
engines are fully spooled up.

The problem is, we're flying light piston airplanes.

Michael

Because in a turn the inside wing is flying at a higher
AOA than the outside wing, the inside wing will likely stall, and
drop, before the outside wing. I understand that in some gliders
without the newer wing designs this inside wing stall may well be
followed an eye-blink later with an out-the-bottom spin entry.
Actually, this is a common misconception, but there is no such thing as an
inside wing stall on any turn, unless it is a very shallow turn in a
pre-stall configuration, and the pilot suddenly applies aileron opposite the
turn, in which case the inside wing will stall first.

This is the common situation when pilots are trying to prolong the glide by
holding the nose high and doing skidding turns.
The opposite aileron is the only way to prevent the wings from banking more
(which is what the pilot is erroneously trying to prevent).
That is why, it is repeated so many times, by so many people, so many books,
that you can't spin from a steep turn, only from a shallow turn.

The "Pooch" may be such a glider.

I don't know where you got this from. The Puchacz has absolutely marvelous
characteristics.
I spun and instructed in them for years.

"Gldcomp" wrote in message
om...

That is why, it is repeated so many times, by so many people, so many
books,
that you can't spin from a steep turn, only from a shallow turn.

This is an overstatement. While it is certainly more difficult to spin from
a steep turn, spins are possible from any attitude depending mostly on the
CG position and the general susceptibility of the glider in question to
spins.

I have flown several gliders which would spin from an accelerated stall in a
near 90 digree bank. Whether these gliders spin "over the top" or out the
bottom" depends on the rudder input at the moment of the stall. It's an "E"
ticket ride to be sure.

Bill Daniels

(Brian Case) wrote in message . com...

Second, unfortunatly some of the procedures for making large patterns
with Power have trickled down from the Military and Airlines and have
started to be taught as standard for small single engine aircraft.

Please leave the military out of this argument - all military training
I've been through teaches nice appropriately steep turns in the
pattern. In fighter-type jets (which includes most trainers, such as
T-37s and T-38s) an overhead break will start with a nice steep
(60degree) break turn to downwind, and the continuous 180 degree turn
from downwind to final (which I still love to do in my LS6, from a
nice tight pattern following a low pass) is commonly flown at 30-45
degrees of bank, as required to keep it tight and roll out on final.

On the other hand, civilian light plane training (in the big schools)
is seemingly all geared towards IFR and airline prep - so the emphasis
on low bank angle, stabilized power-on approaches, etc.

Hideous airmanship in a Cezzna or Piper, IMHO! But my at least my
coffee doesn't get spilled when I'm travelling (it no longer counts as
flying) in a Boeing or Airbus tubular extrusion.

Kirk

And as a general statement, it is completely bull****.

There are a lot of gliders which don't have the elevator authority to stall
from a steep bank angle. However, there ARE gliders which can do that. Long
wings help on that, and flying in turblent air like rotors (where you
usually circle with decent bank angles) does help very well.

--
Bert Willing

ASW20 "TW"


"Gldcomp" a écrit dans le message de
om...
That is why, it is repeated so many times, by so many people, so many
books,
that you can't spin from a steep turn, only from a shallow turn.

On Mon, 14 Jun 2004 22:57:59 GMT, "Gldcomp"
wrote:

Because in a turn the inside wing is flying at a higher
AOA than the outside wing, the inside wing will likely stall, and
drop, before the outside wing. I understand that in some gliders
without the newer wing designs this inside wing stall may well be
followed an eye-blink later with an out-the-bottom spin entry.
Actually, this is a common misconception, but there is no such thing as an
inside wing stall on any turn, unless it is a very shallow turn in a
pre-stall configuration, and the pilot suddenly applies aileron opposite the
turn, in which case the inside wing will stall first.

Wow. "... there is no such thing as an inside wing stall on any turn,
unless it is a very shallow turn ...". Maybe it's just me, but I
think I'll just continue to consider this sort of stall something to
be alert to. YMMV.


This is the common situation when pilots are trying to prolong the glide by
holding the nose high and doing skidding turns.
The opposite aileron is the only way to prevent the wings from banking more
(which is what the pilot is erroneously trying to prevent).
That is why, it is repeated so many times, by so many people, so many books,
that you can't spin from a steep turn, only from a shallow turn.

The "Pooch" may be such a glider.

I don't know where you got this from. The Puchacz has absolutely marvelous
characteristics.
I spun and instructed in them for years.

Actually, this is a common misconception, but there is no such thing as an
inside wing stall on any turn, unless it is a very shallow turn in a
pre-stall configuration, and the pilot suddenly applies aileron opposite the
turn, in which case the inside wing will stall first.


I had to think about this for a while. My thought process when
something like this:

If the AOA is the same on the inside and outside wing there will be no
tendency for the wing to stall one way or the other.

In a coordinated turn the AOA should be the same on the inside and
outside wing. This is obviously true in level flight and in 90degree
bank turn.

However in a 45 degree bank turn it is obvious that the inside wing
travels less distance than the outside wing in 360 degree turn, thus
it must be flying at a lower relative airspeed than the outside wing.

It turns out that this is what causes overbanking tendency. To
compensate for overbanking tendancy the aircraft must have short wings
and/or a lot of dihedral. Dihedrall effectivaly increases the wing
area of the inside wing so and increase in AOA is not required. If
there is not enought dihedral for the turn then the overbanking
tendancy must be compensated for by the ailerons which increase the
angle of attack of the inside wing. Thus you get an inside wing stall.
A 2-33 should demostrate this very will as it has a very large
overbanking tendancy.

Actually, this is a common misconception, but there is no such thing as an
inside wing stall on any turn, unless it is a very shallow turn in a
pre-stall configuration, and the pilot suddenly applies aileron opposite the
turn, in which case the inside wing will stall first.


Expanding on my previous thought process. Execesive Overbanking
tendancy may be the reason that some aircraft won't (or at least are
difficult to) stall the inside wing. The 2-33 for example the
overbanking tendancy is so bad that it may run out of aileron to hold
it in a constant bank turn at low speed. This requires the pilot
either lower the nose or apply opposite rudder to prevent the turn
from getting any steeper, both of which will lower the AOA on the
inside wing. If the pilot allows the bank to get steeper the airplane
runs out of elevator authority and the nose drops on its own
increasing the airspeed and also lowering the angle of attack.

As is almost always the case moveing the CG back will give the
airplane more elevator authority and a better change of being able to
stall the inside wing.