Spinning (mis)concepts

It appears that you have missed my point - but managed to illustrate it very
nicely!
I rest my case.

Allan

"Pete Zeugma" wrote in message
...
At 02:54 31 January 2004, Adp wrote:

Except it isnt is it! Gliders require you to understand
fully things like adverse yaw, energy management, not
being able to power-on and go around. When you land
a glider, you only get one shot at it, what ever the
conditions happen to be thrown at you. How much time
do you spend thinking of where you are going to land
out when you are at 1500 feet above the ground in
your power plane? It has nothing what ever to do with
irrational prejudice.

This is one of the biggest nonsense myths in the soaring
community. It
amounts to an irrational prejudice towards power pilots
who transition to
gliders.
There is considerably greater difference between, say,
flying a Bonanza and
flying a Boeing 757 than flying any glider.
Gliders are incredibly easy to fly. Simply be aware
of the differences.
It really amounts to attitude. (In both senses of
the word.)
When flying a Bonanza, think Bonanza. When flying
a King Air, think King
Air. When flying a B-757, think 757. When flying
a F18, think F18. When
flying a glider, think glider. When flying a motor
glider, think glider.
It can't be much simpler.

Allan

'Mark James Boyd' wrote in message
news:401acc7c$1@darkstar...
Pete Zeugma wrote:

Ah, power planes, not gliders! Do you not think perhaps
we should be differentiating between rudder usage
in
power plane, and a glider? I started flying originally
in gliders, so I dont have any bad habits from power
flying, and when I fly powered aircraft, i cant help
but fly coordinated all the time. I know that power
pilots who make the transition to gliders quite often
make fundemental errors due to the power mindset when
sat in a glider. What do you think?

Absolutely there are subtle differences that get overlooked.
Primacy is a factor here. Use of spoilers, wheel
brake
not at the feet, no stall horn, can't use throttle
to
descend, actually seeing adverse yaw, etc. All these
were probably much harder to learn (unlearn) than
if
one started as a glider pilot first.

....Snip....

Todd Pattist wrote:

Robert Ehrlich wrote:

One of the ideas behind this integrated terminology is that
neither skid nor slip is an appropriate maneuver in today's
gliders having powerful airbrakes, morever on some of them
the POH prohibits skids and/or slips.

I don't see how a POH could entirely prohibit slips - as you
could never land in a crosswind. :-)


Well, the method taught at present time for crosswind landing
in France is to correct for the crosswind by having the nose
pointed into the wind by just the amount necessary to compensate
for this crosswind so that the flight path remain aligned with
the runway, while the wings are kept level and the string in the
middle, up to just before touchdown, where rudder is used to
re-align the axis of the glider with the axis of the runway.
At this time, stricly speaking, you are effectiveley slipping,
even if the POH prohibits it. For such a short time it does not
really matter.

Todd Pattist wrote:

I don't see how a POH could entirely prohibit slips - as you
could never land in a crosswind. :-)

I don't see how slipping and crosswind correction could be related, as
the only correct way cope with crosswind is crabbing. Oh wait, I just
started another famous winter thread...

Stefan

In article ,
Tom Seim wrote:

The size and importance of this error is another
matter entirely :PPP

Well, the size and importance DOES matter because you are making such
a point of it. I think that I adequately proved that your last point
was, shall we say, pointless. The offset of the yaw string to the
center of the roll axis is much less than its displacement from the
CG, making your "errors" proportionally less.

First of all, I believe the size and importance is worthy of
discussion, I just usually separate noticing an error and
figuring out how important it is into two parts.

I was ALSO hoping someone else would do the
math so I didn't have to :PPPP

In another vein, the forward of CG vs. above CG is totally different,
because the "above CG" is about roll rate (which can be
significant) while the "forward of CG" isn't about yaw rate (which
would be hard to sustain at a high rate for several seconds
without running out of rudder.) So I'm talking about
two completely different possible sources of error.

In the end, however, after SWAG calculations, it looks like at
very high roll rates (90 deg in 4 sec), and yaw string
displaced 2 feet+ from the CG/center of pressure, at very
low speeds (30 knots), the trig indicates 1-2 degrees
of error. Bigger than the forward yaw string error, but
still dwarfed by the asymmetric AOA's caused by
long wings, high bank angles, and aileron AOA.

I think you ought to
pursue a more reasonable hypothesis; like TWA 800 was downed by a
stray Navy missle.

Tom

Well, a negative result is sometimes useful for someone.
And besides, it's not like I'm writing about
gliding on MARS or something, for goodness sake :PPP

I know there were a few with rudders, but I don't think I've ever seen one.
I did see the Mooney re-hash a few years back. Ugly.
I loved flying it but my wife wouldn't even consider buying one because it
_didn't_ have rudder pedals.
Cheers!

Todd Pattist wrote in article
...
"George William Peter Reinhart" wrote:

Todd,
Ever try to slip an Ercoupe?

With or without the uncoupled rudders mod :-)

(It has its wheels behind the CG - my glider doesn't)

Todd Pattist - "WH" Ventus C
(Remove DONTSPAMME from address to email reply.)

Stefan wrote:

Todd Pattist wrote:

I don't see how a POH could entirely prohibit slips - as you
could never land in a crosswind. :-)

I don't see how slipping and crosswind correction could be related, as
the only correct way cope with crosswind is Oh wait, I just
started another famous winter thread...

Stefan

But crabbing ends by uncrabbing, and this is slipping.

Robert Ehrlich wrote in message ...

One of the ideas behind this integrated terminology is that
neither skid nor slip is an appropriate maneuver in today's
gliders having powerful airbrakes, morever on some of them
the POH prohibits skids and/or slips.

Can you give some examples of glider POH that probibit slips or skids.
I don't think anything I have flown has such a probibition.

I make a point of practicing at least one full airbrake, full rudder,
slipping approach at the start of every season. I get plenty of
opportunity to practice shallow approach angles from contest finishes.

And yes, I have needed to use the technique for a field landing in the
past. I was very glad I was familiar with flying a stable approach
with zero indicated airspeed (ASW 19 with pot pitot).


Andy

I don't have the time right now, but anyone care to hazard a few lines
of discussion on the increase in induced drag during a slip and
compare it with the high speed, high drag descent Cindy described?

It might start something like this:

During a slip, the effective span and aspect ratio of the wing and
elevator decrease substantially. Additionally, total lift required to
maintain a constant airspeed is much increased (without any increase
in g loading) due to the tilting of the lift vector. Therefore, a much
higher angle of attack is required to maintain a given (low) airspeed,
one which might be employed to accomplish a steep approach into a very
short field.

Different circumstances, of course. But it would be interesting to see
someone develop this. Frankly, I don't think I've ever seen an
analysis of a slip that properly weighs the effects of induced drag.

Just out of interest, Cindy, according your data, which creates the
steepest approach (min L/D) (as opposed to greatest sink rate)? Yes,
we're likely to get some discussion on TV airbrakes, but we'll just
have to suffer through that.

Cindy, perhaps you would address that bit of nonsense in the Private Pilot
Practical Test Standards about no-spoiler accuracy landings. (I've always
thought it was there in order to make the PTS 2-33 specific.)

Bill Daniels

"Caracole" wrote in message
om...
Aerodynamics 101.
Parasitic drag as a topic.
If you truly want down fast, a slip is not the most effective tool.
AS-K 21, full spoilers deployed and 90 knots airspeed will descend at
4000 fpm.
You are below both maneuvering and rough air speed.

Slipping turns are a useful tool. They should be understood.
So should parasitic drag. Try it at altitude. Carry a GNSS recorder
(GPS logger for us unruly Americans). Analyze the data later about
how much sink rate you manufacture.

Don't believe it? Come fly with us. Or watch from the ground if you
wish. It works for everything from 1-26s up to Nimbus 3s and all the
standard class stuff inbetween. There are no too-little or
ineffective spoilers, just mild differences in sink rates.
Now, the AS-W 12, that's a different story.....until they fitted a
fitful drogue chute. Or the Carbon Dragon.

Slipping on approach to landing (or anytime), pitch attitude is your
friend for airspeed control.

Cindy B
www.caracolesoaring.com



What speed did you use? Could you have just used full
spoilers and
spiralled down at 90 knots or so (or faster, if air
was smooth), and had
the same descent rate?
--
-----
change 'netto' to 'net' to email me directly

Eric Greenwell
Washington State
USA

80kts in an ASK-21, but who knows the accuracy of
an ASI in a slip? I was turning to the left with full
right rudder and the nose as far down as I dared; the
noise was tremendous.

At 10:00 04 February 2004, Adp wrote:
It appears that you have missed my point - but managed
to illustrate it very
nicely!
I rest my case.

Allan


Hardly, been busy and away from the office. Plus pilotnet
has been down the last couple days. This just fills
in my time between while waiting for software builds
to complie. Mind you, your theories on flight dynamics
have caused intence amusement here. several posts are
currently on our main notice board collecting comments
from within the flight dynamics group!