H201 Libelle and wing dropping

JC wrote in message ...
On Fri, 15 Oct 2004 15:59:52 GMT, "Bill Daniels"
wrote:


"ruediger" wrote in message
. com...
Since 3 month I am proud owner of a H201B with 17m wingspan and
"Speizklappen". The glider I owned for 4 years, before i bought the
Libelle was a Astir CS77. I like the handling of the Libelle very
much, the only point I really have problems with, is that the Libelle
loves to drop a wing at the beginning of aero tow. Every take off that
a friend or me made with the glider was close to a aborted take-off.
Other Libelle Pilots said, I should try to open the air breaks for the
first 100m, but none of them owns a 17m version, which has extra
weight on the outer side of the wing because of the wingtip extension.

I am not used to this wing dropping by the ASTIR so I hope I can get
some additionell advice here.

It's an accepted fact that extending the spoilers or selecting negative
flap
will enhance aileron control at low speeds. The magnitude of the effect
differs for various gliders so consultation with pilots experienced with
a
particular glider is advised.

That said, there is another factor that may be involved.

I recall watching the grid depart at a regional contest where each glider
in
turn dropped the upwind wing. There was about a 8 knot crosswind
component.

After watching the show for a while I started to realize that the tugs
prop
blast was drifting with the wind and striking the gliders down wind wing
causing it to rise violently. The onset of the effect occurred when the
glider had rolled about half the length of the tow rope or just after the
wing runner had released the wing tip.

When my turn came, I got ready to stuff in a lot of down wind aileron at
just the point where the glider encountered the tugs prop blast. It
worked
nicely and I didn't drop a wing like those before me. Now I'm always
ready
for the drifting prop blast.

Bill Daniels

In the commercial operation I used to run I saw this same wing drop
due to prop blast in the longer winged planes, specifically the Nimbus
2 and a ASW-22. I kept a 300 ft rope just for towing these guys. The
longer rope solved the problem.

You may wish to make up a 100 foot "weak link" to be used when towed,
(Assuming they are starting with a 200ft.) It would most likely
solve your problem.

I fly a Nimbus 2C and just being alert to the possibility of prop blast
drift has worked for me so far. I like the idea of a longer rope though.

Bill Daniels

To prevent wing drop in Libelles:

Longer tow rope. 250-300 feet works well.

Start with open divebrakes on the 201 during the initial roll. But, be
very careful here. The Libelle's brakes aren't very powerful which makes
a brakes open on tow problem especially insidious. If they are open
after lift off, the tug driver probably won't notice immediately. You
will be way down the runway when you and the tuggy realize that
something is wrong. Take it from one who knows ; )!

Use negative flap on the 301. Works even better than opening the
divebrakes on the 201 and doesn't have the inherent hazard of open
brakes on tow.

Stick full forward from the beginning of the takeoff roll until the tail
comes up. This will get you aileron authority as quickly as possible.

My 301 has Kestrel landing gear which is even taller than the original
301 gear. This makes for an even greater potential for wing drop. Using
the above techniques, I rarely ever have a wing drop, even when being
towed by weak tugs.

--
Take out the airplane for reply

Wallace Berry wrote:
To prevent wing drop in Libelles:

snip


Stick full forward from the beginning of the takeoff roll until the tail
comes up. This will get you aileron authority as quickly as possible.

I suggst that this is not good practice in a cross-wind takeoff, where
you want the tail wheel firmly on the ground to help keep the glider
straight. It is probably not necessary in any case: by the time you are
going fast enough to lift the tail, aren't the ailerons already so
effective you won't drop a wing?


--
Change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

In article ,
Eric Greenwell wrote:

Wallace Berry wrote:
To prevent wing drop in Libelles:

snip


Stick full forward from the beginning of the takeoff roll until the tail
comes up. This will get you aileron authority as quickly as possible.

I suggst that this is not good practice in a cross-wind takeoff, where
you want the tail wheel firmly on the ground to help keep the glider
straight. It is probably not necessary in any case: by the time you are
going fast enough to lift the tail, aren't the ailerons already so
effective you won't drop a wing?

What you state is exactly what I would expect. But, for whatever reason,
holding forward stick on my 301 seems to help significantly with
avoiding a wing drop. Even with the stick forward, the rudder is
effective before the tail comes up. So far, no problems with cross wind
take offs, which they nearly all are at our site. One thing I forgot to
mention, my Libelle only has the CG hook, the nose hook having been
glassed over by a previous owner. Because of this, the tail on my 301
tends to stay down a bit longer than one being towed by the nose hook.
With a long rope, negative flap and the stick forward, I've done
unassisted takeoffs with no trouble. Haven't tried that with a strong
crosswind.

--
Take out the airplane for reply

Wallace Berry wrote:
In article ,
Eric Greenwell wrote:


Wallace Berry wrote:

To prevent wing drop in Libelles:

snip


Stick full forward from the beginning of the takeoff roll until the tail
comes up. This will get you aileron authority as quickly as possible.

I suggst that this is not good practice in a cross-wind takeoff, where
you want the tail wheel firmly on the ground to help keep the glider
straight. It is probably not necessary in any case: by the time you are
going fast enough to lift the tail, aren't the ailerons already so
effective you won't drop a wing?


What you state is exactly what I would expect. But, for whatever reason,
holding forward stick on my 301 seems to help significantly with
avoiding a wing drop. Even with the stick forward, the rudder is
effective before the tail comes up. So far, no problems with cross wind
take offs, which they nearly all are at our site. One thing I forgot to
mention, my Libelle only has the CG hook, the nose hook having been
glassed over by a previous owner. Because of this, the tail on my 301
tends to stay down a bit longer than one being towed by the nose hook.
With a long rope, negative flap and the stick forward, I've done
unassisted takeoffs with no trouble. Haven't tried that with a strong
crosswind.

I got confused about who was flying what, and my comments were intended
for a 201. My 301 didn't drop a wing as long as I started in full
negative flap. It's been 20 years, but I think I used some back stick at
the start. Mine did have the nose hook.


--
Change "netto" to "net" to email me directly

Eric Greenwell
Washington State
USA

"Wallace Berry" wrote in message

One thing I forgot to
mention, my Libelle only has the CG hook, the nose hook having been
glassed over by a previous owner. Because of this, the tail on my 301
tends to stay down a bit longer than one being towed by the nose hook.
With a long rope, negative flap and the stick forward, I've done
unassisted takeoffs with no trouble. Haven't tried that with a strong
crosswind.

Using the nose hook will reduce the tendancy for wing drops.

Bob Salvo

"Bob Salvo" wrote in message
...

Using the nose hook will reduce the tendancy for wing drops.

Bob Salvo

Really? Why?

Bill Daniels

Bill,

Not sure, but when I sealed over my nose hook on the H301 and used the CG
hook for aertow, I had more trouble keeping a wing from dropping. I think
when the CG hook is used and there is a wind gust from the side at the start
of launch, there is more tendancy for the tail to swing, which usually
produces some roll. Using the nose hook, which is well in front of the
wheel, reduces the tendancy for a swinging tail. Another interesting thing
I found about using the nose hook is that if the ship happens to vere
towards, say the left, and the left wing starts to drop, the pull force of
the tow rope will try to roll the ship, lifting the wing. I believe this is
because of the larger moment arm (height) between the nose hook and the
pavement. On the other hand, the CG hook is a very close to the pavement,
so there is very little moment force to assist in rolling the ship back to
level. Of course, this could be a disadvantage if the roll force caused by
the tow is holding the wing down. But there are some cases when a wing
drops that releasing is the best thing to do. BTW when using the CG hook
(when there is little rolling force from the tow), I have found that the use
of rudder to pick up a wing works very well if I rudder (turn) towards the
wing that drops. When the ship is forced to turn in the direction of the
dropping wing, the ship will roll to bring the wing back up. Its like
riding a bicycle: if you happen to start falling to the left, you should
steer to the left, otherwise you will fall over. I'm sure that there are a
lot of pilots out there that don't believe this, but that's OK; this method
works for me.

Bob Salvo

"Bill Daniels" wrote in message
news:MBefd.247116$wV.107530@attbi_s54...

"Bob Salvo" wrote in message
...

Using the nose hook will reduce the tendancy for wing drops.

Bob Salvo

Really? Why?

Bill Daniels