Spinning (mis)concepts

In article ,
Chris OCallaghan wrote:
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.

Well, the 2-33 manual says in a full slip that something like
45 to 50mph gives the most efficient slip.

I wonder if this means most amount of altitude loss
for distance travelled, or highest sink rate per
minute. I'd believe the first, but have trouble
believing the second.

And if it really is just best altitude loss for
distance of glide, then wind effects could change
the correct speed significantly...

Well, not only have you missed my point but you have confused me with
someone else.
To what theories of flight dynamics are you referring?
I don't have any theories on flight dynamics.
It also seems that your "group" is starved for items of amusement.
My theory on spinning is simple - don't get into one and you won't have to
recover!
My point, to which you took exception, had to do with the thought that power
pilots
are deemed to be inferior to ab initio glider pilots when learning to fly
gliders and that
power training is of little use when transitioning to gliders.
Having run into this perception multiple times, I pointed out that it is
nonsense.
The few differences that define glider flying are small when compared to the
differences
between powered aircraft.
Aerodynamics are aerodynamics. They apply to gliders, powered aircraft,
buzz bombs and flat plates.
You just have to be aware of the differences.

Allan


"Pete Zeugma" wrote in message
...
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!

Pete,

It sounds like you have the axioms down pat, but are having a little
trouble with recognizing that the controls allow pilots to do all
sorts of things that the designer didn't intend. Of course you can
(not should) rudder a glider wings level around a turn. Just like the
rudder on a boat. This is commonly called a skid.

Frankly, I can't tell whether you are trolling or exhibiting genuine
ignorance. Let's hope it is the latter -- there's a cure for what you
don't know. At any rate, I'd stop arguing on this point until you've
had a discussion with a CFI, power or sailplane. Your heart appears to
be in the right place. (It's the wings that turn an aiplane. The
rudder is to counteract adverse yaw.) But you're failing to recognize
how a pilot can abuse the controls to a variety of ends. Slips are
one. Skidding turns another. Stalls still another. Some are useful.
Some less so. Skidding turns fall into the second category.

"Bill Daniels" wrote in message ...
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


When I was more active instructing I used to give students simulated
airbrakes jammed full open and jammed closed (separate flights). I
expected them to demonstrate that they could complete the circuit and
landing. I released the malfunction on short final, or sooner if they
couldn't cope.

Isn't the PTS requirement to demonstate simulated jammed closed?


Andy

"Bill Daniels" wrote in message ...
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

That would have to be "Schweizer specific" at the very least wouldn't
it, Bill? I was once forced by reason of a 2-32's spoilers being
frozen solidly closed to slip from 28,000 ft MSL near Pikes Peak to
land without them at old BFGP. (Not much of an accuracy landing
challenge there, of course, but my feet were pretty cold and I was
grateful for the rate of descent). FAA's aircraft registry lists at
least 1335 Schweizers having spoilers or divebrakes of similar
configuration, of which 2-33's of all varieties number only 375.

I'm embarassed to admit that I've also inadvertently jettisoned the
drag chute on a Salto on the base leg to a much smaller landing site
where I really could have used it, and an agressive slipping turn to
final made the difference between an otherwise certain overshoot and a
merely memorable pattern. Modern sailplanes don't ordinarily present
as much flat plate to the airstream and plummet from altitude quite as
dramatically as the Schweizers, but they all descend a bit more
steeply flying sideways and there are any number of reasons that extra
little increment of drag may be useful.

As training exercise, I'd argue that no-spoiler slipping patterns to
an accuracy landing can be uses to develop advanced levels of both
judgement and command of the aircraft in maneuvering with attention
focused largely outside the cockpit. In that sense, is demonstrating
proficiency in it any less "practical" a test item than some of the
ground reference maneuvers found in the airplane PTS?

"Eric Coleson" wrote in message
om...
"Bill Daniels" wrote in message
...
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

That would have to be "Schweizer specific" at the very least wouldn't
it, Bill? I was once forced by reason of a 2-32's spoilers being
frozen solidly closed to slip from 28,000 ft MSL near Pikes Peak to
land without them at old BFGP. (Not much of an accuracy landing
challenge there, of course, but my feet were pretty cold and I was
grateful for the rate of descent). FAA's aircraft registry lists at
least 1335 Schweizers having spoilers or divebrakes of similar
configuration, of which 2-33's of all varieties number only 375.

I'm embarassed to admit that I've also inadvertently jettisoned the
drag chute on a Salto on the base leg to a much smaller landing site
where I really could have used it, and an agressive slipping turn to
final made the difference between an otherwise certain overshoot and a
merely memorable pattern. Modern sailplanes don't ordinarily present
as much flat plate to the airstream and plummet from altitude quite as
dramatically as the Schweizers, but they all descend a bit more
steeply flying sideways and there are any number of reasons that extra
little increment of drag may be useful.

As training exercise, I'd argue that no-spoiler slipping patterns to
an accuracy landing can be uses to develop advanced levels of both
judgement and command of the aircraft in maneuvering with attention
focused largely outside the cockpit. In that sense, is demonstrating
proficiency in it any less "practical" a test item than some of the
ground reference maneuvers found in the airplane PTS?

I've watched pilot attempt a no-spoiler approach in a Grob 103 and the only
way that a reasonably accurate landing could be done was to fly way too slow
for comfort because the 103 floats so far in ground effect. My Nimbus 2C
(No tail 'chute) floats so far that if the air brakes don't work, I'll need
several kilometers of runway to get stopped.

If you have a glider that exhibits a pronounced float in ground effect, I'd
advise against a no-spoiler approaches. I think this may be where accidents
due to training will be greater than those due to a real spoiler failure.

Bill Daniels

At 18:30 04 February 2004, Adp wrote:
My theory on spinning is simple - don't get into one
and you
won't have to recover!

strangly, thats basically what ive been saying all
along, and objecting to the 'experts' who insist its
ok to turn a glider using rudder alone!

My point, to which you took exception, had to do with
the
thought that power pilots are deemed to be inferior
to ab initio
glider pilots when learning to fly gliders

didnt mention ab initio at all, neither did i say they
were inferior.

and that power training is of little use when transitioning
to
gliders.

actually i said that there was a degree of unlearning
and bad habits that typically show up, in this particularly
instance the general theme was in the misuse of the
rudder pedals and the misguided belief that because
you can do something in a powered aircraft the same
must apply to gliders.

Having run into this perception multiple times, I pointed
out
that it is nonsense.

you may well think so in your own experiences, however
it still remains true. old habits are hard to break,
especially when they become instinctive.

The few differences that define glider flying are small
when
compared to the differences between powered aircraft.

and it is those small differences which when wrongly
applied to glider flight can rapidly end life!

Aerodynamics are aerodynamics. They apply to gliders,

powered aircraft, buzz bombs and flat plates.
You just have to be aware of the differences.

no argument there.

"Bill Daniels" wrote in message

If you have a glider that exhibits a pronounced float in ground effect, I'd
advise against a no-spoiler approaches. I think this may be where accidents
due to training will be greater than those due to a real spoiler failure.

Bill Daniels


I think the distinction should be made between no spoiler
patterns/circuit/approaches and no spoiler landings.

I think a simulated jammed closed, or jammed open, situation is useful
training but, as I said earlier, I always released the malfunction on
short final. The landing float was not an issue as spoiler/airbrake
could be used for the landing.

When doing simulated engine fails with airplane pilots I always make
it clear that the engine is available on short final. No point in
busting the airplane with a hard landing.


Andy

Pete Zeugma wrote in message ...
strangly, thats basically what ive been saying all
along, and objecting to the 'experts' who insist its
ok to turn a glider using rudder alone!


Pete,

No one in this group has suggested it is "OK to turn a glider using
rudder alone." In an earlier post you stated in no uncertain terms
that turning a glider with rudder only was an aerodynamic
impossiblity. You then "proved" your point by stating that unbalanced
movement of the rudder produces a forward slip. Is it surprising that
several of the group's readers, ones who lay hands on the controls
occasionally, took exception?

Your absolutism isn't uncommon. It is a tool used by good students to
learn and apply their lessons. It is especially common in flight
training, where instuctors must daily grapple with the fact that they
are giving their students access to an environment that capitalizes on
any lack of experience and exacts a brutal cost when it finds pilots
wanting. An axiomatic approach is warranted -- a short cut, proven to
be a fair trade between rapid progress to certification and safety in
the air. A pilot can even afford to arrest his development at this
point, but if you are going to engage in discussions on the philosophy
of flight, you'll need to start looking behind the short cuts your
flight instructor proffered to keep you safe in the air.

I assume your need for a strawman is a first step in overcoming
denial. That's a good thing. Get past this.

At 13:42 05 February 2004, Chris Ocallaghan wrote:
Your absolutism isn't uncommon. It is a tool used by
good students to learn and apply their lessons.

its also an approach used as an instructor, for good
reasons.

It is especially
common in flight training, where instuctors must daily
grapple
with the fact that they are giving their students access
to an
environment that capitalizes on any lack of experience
and
exacts a brutal cost when it finds pilots wanting.


quite right. so does it not make you rather disturbed
when you read posts the suggest that its you can turn
a glider with rudder alone? what brutal cost will that
exact on the poor sod who reads some of todds posts
and puts it into practice when flying low and slow,
'oh, todd said i can make a flat turn using my rudder'

An axiomatic approach is warranted -- a short cut,
proven to
be a fair trade between rapid progress to certification
and
safety in the air.

actually, there is no warrented approach or short cut
between progress and safety in the air. basic understanding
of the correct use of controls and why it is so important
to engrain into a student the necessity to fly coordinated
in turns at all times.

A pilot can even afford to arrest his development at
this
point, but if you are going to engage in discussions
on the
philosophy of flight, you'll need to start looking
behind the
short cuts your flight instructor proffered to keep
you safe
in the air.

my instructor, some 28 years ago now, taught me well.
he drilled into me why you fly turns correctly, why
you dont over rudder in turns. the gliders flown way
back then had a habit of killing those who did not.
i dont know of any instructor who looks for short cuts.


go read the BGA instructors manual. it explains quite
nicely why right from the first moment it should be
drummed into a trainees head 'that the rudder does
not turn a glider like a boat' and if you disagree,
email the BGA and give them your little gems of wisdom.

I assume your need for a strawman is a first step in

overcoming denial. That's a good thing. Get past this.

if being in denial is to confront and challenge techniques
used by power pilots being encouraged or suggested
to be used with gliders then so be it. If challenging
claims that a glider will turn wings level just with
the rudder alone, due to the fuselage generating lift,
then so be it.

or do you not think you have a duty of responsibility
to prevent accidents and death..... if you have not
noticed, there is already one low-time pilot who has
picked up on some of the ideas stated here, and is
thinking of trying them out..........