Spinning (mis)concepts

At 01:42 30 January 2004, Mark James Boyd wrote:
In article ,
Todd Pattist wrote:

As a matter of interest, how did you handle the request
to
demonstrate a 'no airbrakes' landing where you needed
a
forward slip on both base and final? Did you bring
the
rudder fully through to the opposite side (inside of
the
turn) to intersperse a coordinated turn between your
forward
slips?

Yep. Exactly. I've used slips in taildraggers extensively,
during no-flap demonstrations, and on lots of checkrides.
Always interspersed a coordinated turn. Kinda funny
to write it here now that I think about it. Just something
I haven't done before, I can't really explain why...



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?

At 07:00 30 January 2004, Marc Ramsey wrote:
Pete Zeugma wrote:
We discovered that there was some packaging that prevented
the full travel of the airbrake.

What do you mean by 'some packaging'?


cant remeber the exact details, but it was either packing
or a spacer in the control rods at the wing root or
in the rods for the airbrake handle. Give val at our
club an email (london gliding club) and ask her to
get the workshop to give you further detail. After
this was removed from our duo it was much better and
we no longer have to do side slipping finals. Before
this I always thought that the blades did not appear
to be fully clear of the wing slot.

"Marc Ramsey" wrote in message
...
Eric Greenwell wrote:
If I understand this right:

1) you are coming down more steeply at 70 knots than you did at 60
knots, but it's still not steep enough;
2) and that's because at Truckee, you want to come in _very_ steeply
over/near the threshold to avoid the downwash off the end;
3) and at 80 knots, the descent would be steep enough, but you'd be
stopping wwaaayyy at the other end.

You've got it. The spoilers don't provide a lot of drag, so it takes a
bit of distance to burn off the extra 10 to 20 knots before making a
normal touchdown. You can fly it on and hit the fine hydraulic brake,
but then it will slam down on the nosewheel, making your partners
nervous...

I've only made a couple of landings at Truckee, so I'm trying to picture
the situation.

For those who don't know, gliders at Truckee (near Lake Tahoe, elevation
5900 feet) normally use runway 19, which features a cliff-like drop off
at the threshold. In the afternoons, the winds are often between 15 and
30 knots right down the runway, which sets up an interesting rotor-like
condition just before the threshold, resulting in big sink and a
significant wind gradient. We normally try to arrange things on windy
days so the turn from base to final is over the numbers. But sometimes,
circumstances prevent that, like a Skyhawk put-putting along on final,
in which case you want lots of extra energy. Let me just say, if you
ever find yourself below the threshold of 19, *push*, then pull at the
last moment, and if you're lucky, you'll end up making a very low energy
landing right on the numbers...

Marc

You might mention there are three turnouts (or at least there were). My
first landing there, I radioed I'd take the first, but ended up taking the
third due to high altitude energy and poor wheel brake;^)

Furthermore, there's been more than one incident there. It is better to be
high and hot than the alternative. Rocks is hard.

Still, a lovely place to fly.

Frank Whiteley
Colorado

"Pete Zeugma" wrote in message
...
At 04:30 30 January 2004, Marc Ramsey wrote:

For those who don't know, gliders at Truckee (near
Lake Tahoe, elevation
5900 feet) normally use runway 19, which features a
cliff-like drop off
at the threshold.

How long is your runway? Club I fly fairly often at
in Scotland, Deeside GC (Aboyne), has quite wonderful
rotor/curlover/wind shear right down to the deck in
strong southerlies. It has two thin (5m and 7m ish)
parallel runways about 500m long (all figs approx)
situated between two ridgelines. There are two windsocks
either side of the runways, and in these strong southerlies
the socks are generally pointing in opposite directions.
I've had many a fast landing there in these conditions,
80-90knots is quite typical. It is common practice
to run on all the way to the end of the runway, to
keep it clear at all times. Of course, what you forget
to mention is that these are airspeeds, not ground
speeds. Landing a glider at 90knots ground speed is
very exciting!


When I flew at Aboyne, there was only one runway, a gravel pit at one end,
and stone fence at the other. Landing with rotor over the airfield was
_really_ interesting as the ASI didn't settle until about 5 feet off the
deck, swinging 30-70kts all the way downwind, base, and final. Radios were
important. The one sod with the broken radio flew a right hand circuit when
all others were flying left. He ( Open Diamant ) landed behind RAF L-13
(land long!) and in front of K-8(land short!). All three touched down at
the same moment and only just behind me. However, four wave flights in a
week and Gold altitude (4000ft cloud climb included). What a treat,
including the low-levels by the Buccaneers and Jaguars!

Frank Whiteley
Colorado

F.L. Whiteley wrote:
You might mention there are three turnouts (or at least there were). My
first landing there, I radioed I'd take the first, but ended up taking the
third due to high altitude energy and poor wheel brake;^)

Use of the first turnout by gliders is now actively discouraged, due to
the potential for taking out a towplane or glider in the tie-down area.
The second one has been expanded, which is quite helpful. The third
one is there, and I use it when necessary, but it is not possible to
clear the runway without getting out and pushing.

Furthermore, there's been more than one incident there. It is better to be
high and hot than the alternative. Rocks is hard.

Indeed.

Still, a lovely place to fly.

That it is.

Marc

At 14:48 30 January 2004, Todd Pattist wrote:
Pete Zeugma wrote:

Before
this I always thought that the blades did not appear
to be fully clear of the wing slot.

When blades are fully clear of the wing slot, you have
to be
certain that air loads will not flex them sufficiently
to
prevent them from re-entering the wing slot.

Thats probably why there is a placarded max rough air
speed!

Personally I dont touch them above this, unless I am
flying in known icing conditions where i crack them
open every now and then to make sure they have not
frozen (at a speed less than max rough air)

I presume the
modification you made (if that's what it was) was in
accordance with factory recommendations.

The problem here was that there was something left
in by the manufacturer that prevented full travel.
The offending item (which I cant remember exactly)
was removed in consultation with Schempp-Hirth by our
workshop.

I know some Grobs
had this problem, and the fix was to limit airbrake
throw
specifically to prevent the blades from clearing their
slots, thereby ensuring they could not lock the brakes
open.

The problem here was about inefectual power in the
brakes as they did not open sufficeintly enough (i
think ours only open half their designed throw) hence
Marc saying he has to side-slip to get a good decent
rate with full brake open.

Todd Pattist wrote:
...
A skidding turn, as you described is the opposite of a
slipping turn. The student needs to be taught the
difference. If he is doing a slipping turn, the yaw string
will be out of the turn, if he's skidding it will be inside
the turn.
...

This terminology is or was source of a lot of discussions and
misconceptions also in France where 2 equivalent terms exists,
"glissade" for slip, "dérapage" for skid. So the team responsible
for deciding the method and terminology that should be used
by all glider instructors decided, after some discussion, that only
one term should be used, "dérapage" was the choosed one.
During a turn, a slip should be called "dérapage intérieur"
(inside skid), a skid "dérapage extérieur" (outside skid).
In straight line we speak of "dérapage à gauche" (skid toward
left side) or "dérapage à droite" (skid toward right side).
This has the advantage of uniformity, any case where the string
is not in the middle is called by the same name and the further
qualification (inside, outside, left, right) always indicate the
side from which the relative wind is coming and the string is going
away.

At 14:48 30 January 2004, Todd Pattist wrote:
Pete Zeugma wrote:

Before
this I always thought that the blades did not appear
to be fully clear of the wing slot.

When blades are fully clear of the wing slot, you have
to be
certain that air loads will not flex them sufficiently
to
prevent them from re-entering the wing slot.

Dug out a photo i took on decent in the discus I fly
so you can see the extent of full travel of a schempp-hirth
airbrake. The blades are clear of the slot, as designed
to be.

http://uk.f2.pg.photos.yahoo.com/ph/...l?.dir=/glidin
g&.dnm=Save0018.jpg

link should work, hopefully!


I presume the
modification you made (if that's what it was) was in
accordance with factory recommendations. I know some
Grobs
had this problem, and the fix was to limit airbrake
throw
specifically to prevent the blades from clearing their
slots, thereby ensuring they could not lock the brakes
open.
Todd Pattist - 'WH' Ventus C
(Remove DONTSPAMME from address to email reply.)

Judy Ruprecht wrote:

See the US Private & Commercial Glider Practical Test
Standards, Area of Operation IV on landings, Task R,
Slips to Landings. See also the Soaring Flight Manual
and its new FAA-published successor (whose name escapes
me).

Judy

Can't you just reduce the throttle and then desc...

Hey WAIT A MINUTE!?!?

....there it is, big as can be, "TURNING SLIPS TO A LANDING"!

right there in the PTS. I coulda read it 200 times and never
actually seen it. This ain't in that darned airplane PTS.
And it wasn't in my training, and it wasn't on any of my
checkrides.

But now I'll practice and teach it. This is one more tool
in my toolbox.

Thanks!

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.

And the whole idea of energy management for rollout and
taxi was completely new, and the one wheel thing
and possibility of groundloop, etc. etc. etc.

Absolutely there are bad habits from transition.
And catching all of them is unlikely without additional
study by the student or new pilot. Instruction and
experience only go so far...study and discussion for me
seem to take it that extra step...

Cheers!

Mark