Schweizer 1-35 and other flapped sailplanes

Hi All,

I have a 1/5 share in a 1-35 here in Alaska. I find
this glider a delight to
fly and the flaps seem to work just fine for approach
control. Once at 30
degrees I can modulate between 30 degs and full without
much trouble just
as I do with spoilers. The nose needs to be pointed
down when adding flaps
and this is quite normal in any aircraft with flaps
that I have flown.
I am amazed at how small an area this glider will land
in. And again how
far it will float at flaps 30. Seems like it has great
spot landing control.

If one is a first timer with flap use there might be
a learning curve that
could best be handled with some dual time in a Cessna
practicing some
power off landings. (I love the older Cessnas with
the manual flaps)

Jeff Banks
N2JY

At 21:36 19 August 2005, Bob Whelan wrote:

Having flown an HP-14 for 195 hours and a much-weenier-flapped
Zuni for
several thousand, all of it out west, and having in
both been concerned
about getting sucked into strong cloud streets, here's
what I did:

1) immediately slowed down (to some speed below which
full flaps could
easily/safely be put down);
2) put down full flaps;
3) changed course to the nearest cloud edge.
4) gave thanks I was flying a flapped ship!

Low stress, structurally safe. Even if one was so
foolish/bold/situationally-unaware as to go into the
cloud immediately upon
the pull-up to slow down, who among us canNOT simply
provide a stick input
until the stall, prior to losing control in the cloud?
If a pilot can do
that, s/he can put down the flaps after the speed bleeds
down. (Individual
mileage may vary. Not approved by the Insurance Institute
of America or the
American Bar Association.)





It would be a lot easier with airbrakes - just open
them.

I have not encountered a situation where this would be an issue near the
clouds. I would just speed up.
I would not mind having spoilers on occasions, when it is necessary to
insert one self into a pattern after many gliders return at the same time in
a contest setting. Even then when I am finally committed to land after I
have given way because I was not able to quickly get into on opening. The
landings are most civilized even
if some one is worse off then I in terms of squeezing in there is always
enough space for gliders to land. One does not always have to land near the
trailer.
Regards
Udo

"Udo Rumpf" wrote in message
...
I have not encountered a situation where this would be an issue near the
clouds. I would just speed up.
I would not mind having spoilers on occasions, when it is necessary to
insert one self into a pattern after many gliders return at the same time
in
a contest setting. Even then when I am finally committed to land after I
have given way because I was not able to quickly get into on opening. The
landings are most civilized even
if some one is worse off then I in terms of squeezing in there is always
enough space for gliders to land. One does not always have to land near
the
trailer.
Regards
Udo

This whole thread says a lot about glider flight training. Airplane pilots
are trained with flaps so they are comfortable with them. Glider pilots are
trained with spoilers, since there are no flapped trainers, so that's what
they are mostly comfortable with.

In fact, a skilled pilot can handle any situation with either.

If there's a situation where a pilot feels uncomfortable, talking with an
instructor skilled in flapped gliders is advisable. (ASK first whether the
instructor has any time in a flap-only glider.)

I have flown both and, although most of my experience is in spoiler equipped
gliders, I prefer flaps for all the reasons the pro-flap folks have listed.
I'll add another. Spoilers, even when closed, disrupt the upper wing
surface in the most critical area - flap only wings are cleaner.

Bill Daniels

Bill Daniels wrote:
Spoilers, even when closed, disrupt the upper wing
surface in the most critical area - flap only wings are cleaner.

And yet, on a well built glider, you can carefully smooth and seal the
spoilers so there is no leakage or surface unevenness, test the glider,
and it isn't any better. My recollection from Johnson's tests is the
most critical area on the wing is the first few inches of the nose (bug
problems), and that the boundary layer is thick enough at the spoilers
that they do not affect the flow on the typical racing glider.

One might also consider how much "disruption" in air flow a Holighaus or
Waibel would tolerate! Even if I'm right about the airflow disruption,
it doesn't negate the principal advantages of flaps, but I think most
pilots would prefer a combination of the two.

There may also be performance issues related to designing a modern flap
only glider: because modern airfoils use such narrow control surfaces, a
flap only glider might not have enough glide path control. I was
astonished at the difference in glide angle between my ASW 20 and my ASH
26 E, even though they employ the same flap system for landing: the ASW
20 descended much more steeply than does my ASH 26. Even though part of
that is likely due to the higher wing loading on the 26, the flap chord
on the 20 is almost double that on the 26.

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

Eric Greenwell
Washington State
USA

Eric Greenwell wrote:
Bill Daniels wrote:
Spoilers, even when closed, disrupt the upper wing
surface in the most critical area - flap only wings are cleaner.

And yet, on a well built glider, you can carefully smooth and seal the
spoilers so there is no leakage or surface unevenness, test the glider,
and it isn't any better. My recollection from Johnson's tests is the
most critical area on the wing is the first few inches of the nose (bug
problems), and that the boundary layer is thick enough at the spoilers
that they do not affect the flow on the typical racing glider.

One might also consider how much "disruption" in air flow a Holighaus or
Waibel would tolerate! Even if I'm right about the airflow disruption,
it doesn't negate the principal advantages of flaps, but I think most
pilots would prefer a combination of the two.

There may also be performance issues related to designing a modern flap
only glider: because modern airfoils use such narrow control surfaces, a
flap only glider might not have enough glide path control. I was
astonished at the difference in glide angle between my ASW 20 and my ASH
26 E, even though they employ the same flap system for landing: the ASW
20 descended much more steeply than does my ASH 26. Even though part of
that is likely due to the higher wing loading on the 26, the flap chord
on the 20 is almost double that on the 26.

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

Eric Greenwell
Washington State
USA

True,
I am building a new wing and I was hoping to include landing flaps
only.
The airfoil was not given me the results I desired with the larger
flaps. I had to reduce the flap size to 16% and install spoilers. The
flap/aileron arrangement will similar to the DG800,
May real preference would be the ASW20/26/27 set-up but I decided to
keep it simple
As for surface aerodynamics the spoilers are always past the laminar
transition. Smooth and sealed spoiler boxes have no ill effect.
In my case the max transition on the top surface will be at 66% and
that is where the box will be installed.
Regards
Udo

Udo wrote:

Eric Greenwell wrote:
There may also be performance issues related to designing a modern flap
only glider: because modern airfoils use such narrow control surfaces, a
flap only glider might not have enough glide path control. I was
astonished at the difference in glide angle between my ASW 20 and my ASH
26 E, even though they employ the same flap system for landing: the ASW
20 descended much more steeply than does my ASH 26. Even though part of
that is likely due to the higher wing loading on the 26, the flap chord
on the 20 is almost double that on the 26.


True,
I am building a new wing and I was hoping to include landing flaps
only.
The airfoil was not given me the results I desired with the larger
flaps. I had to reduce the flap size to 16% and install spoilers. The
flap/aileron arrangement will similar to the DG800,
May real preference would be the ASW20/26/27 set-up but I decided to
keep it simple
As for surface aerodynamics the spoilers are always past the laminar
transition. Smooth and sealed spoiler boxes have no ill effect.
In my case the max transition on the top surface will be at 66% and
that is where the box will be installed.

Interesting! On my ASH 26 E, the flap chord is 15.5% at the root (root
chord 33 inches), and the leading edge of the spoiler cap is at 48%.


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

Eric Greenwell
Washington State
USA

One question for 'flaps only' glider drivers:

On a cross country aero tow, do you ever feel a need
for some type of draggy things to help keep you in
tow position?

If you need a tow speed fast enough to get you home
before the sun sets but that makes it too fast to deploy
flaps, what procedure do you use, if and when necessary,
to keep the towrope tight? Yea, yea, yea, I know:
Fly it properly and you won't need to worry. But
what about when the tuggie snoozes a little and starts
a slight descent and gains speed. (Hey, I'm not even
sure spoilers could help out here.)

Popping spoilers out sure works nicely and easily.

And by the way, I don't like cross-country aerotows.
Sometimes, I think I would rather have the trailer
instead of the towplane.

Ray Lovinggood
Carrboro, North Carolina, USA
LS1-d (No flaps. Spoilers only)

Ray Lovinggood wrote:
One question for 'flaps only' glider drivers:

On a cross country aero tow, do you ever feel a need
for some type of draggy things to help keep you in
tow position?

If you need a tow speed fast enough to get you home
before the sun sets but that makes it too fast to deploy
flaps, what procedure do you use, if and when necessary,
to keep the towrope tight?

"Too fast to deploy flaps" might be an overly-simplified statement of
the situation. How fast are we talking and how much flap are we
deploying? It doesn't take much flap to create significant drag. In
other words, it is likely OK to deploy a little bit of flap at high
speeds. Or perhaps just return them to neutral if you had them
reflexed.


Another nice "trick" is the ability to make the towplane more visible.
Cranking in a little flap such that the glider assumes a slightly nose
down attitude works nicely and easily.

Regards,

-Doug

Unfortunately, I just had the opportunity for an aero retrieve in my PIK-20.
8 deg. positive flap made for a comfortable tow at 70 - 75 knots and held
good tension during the occasional "snooze".


"Doug Hoffman" wrote in message
ups.com...

Ray Lovinggood wrote:
One question for 'flaps only' glider drivers:

On a cross country aero tow, do you ever feel a need
for some type of draggy things to help keep you in
tow position?

If you need a tow speed fast enough to get you home
before the sun sets but that makes it too fast to deploy
flaps, what procedure do you use, if and when necessary,
to keep the towrope tight?

"Too fast to deploy flaps" might be an overly-simplified statement of
the situation. How fast are we talking and how much flap are we
deploying? It doesn't take much flap to create significant drag. In
other words, it is likely OK to deploy a little bit of flap at high
speeds. Or perhaps just return them to neutral if you had them
reflexed.


Another nice "trick" is the ability to make the towplane more visible.
Cranking in a little flap such that the glider assumes a slightly nose
down attitude works nicely and easily.

Regards,

-Doug