Flaps and V-Tails of Death

OK, It's winter time and I'm bored, so let me throw my 2 cents in here. The
only flight I ever had in a ship with flaps only was in a PIK-20B. It was a
test flight after a broken fuselage. Things went well until it got time to
land. I rolled in 45 degrees of flaps and everything looked just about right.
Came over the fence at 50 knots and waited for her to settle down. I waited and
waited and waited. By now I had floated down most of the 4000 foot runway and
I'm still floating about 1 foot off the ground. What do I do? Musn't dump the
flaps or she will drop like a stone, right? Finally got the wheel on the ground
and jumped on the brake.
That night I read the flight manual and it said to slowely crank off the flaps
in this situation. I think the flaps only ships are OK, but require a different
set of skills that must be mastered. Probably not for the low time pilot or
those who don't read the flight manual before flight. My real problem was being
about 5 knots too fast. Proper speed control is critical.
JJ Sinclair

Wallace Berry wrote:

As for getting sucked into a cloud, I would have an easier time keeping
that HP-16 out of the cloud than my Libelle with it's relatively
ineffective divebrakes. I have been in the gear down, full divebrakes
and full slip configuration diving for the edge of the cloud at high
speed to keep from getting sucked in.

The 301 definitely has weak spoilers (good wheel brake, though!), which
is one reason I moved to an ASW 20C.

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Eric Greenwell
Washington State
USA

JJ Sinclair wrote:

OK, It's winter time and I'm bored, so let me throw my 2 cents in here. The
only flight I ever had in a ship with flaps only was in a PIK-20B. It was a
test flight after a broken fuselage. Things went well until it got time to
land. I rolled in 45 degrees of flaps and everything looked just about right.
Came over the fence at 50 knots and waited for her to settle down. I waited and
waited and waited. By now I had floated down most of the 4000 foot runway and
I'm still floating about 1 foot off the ground. What do I do? Musn't dump the
flaps or she will drop like a stone, right? Finally got the wheel on the ground
and jumped on the brake.
That night I read the flight manual and it said to slowely crank off the flaps
in this situation. I think the flaps only ships are OK, but require a different
set of skills that must be mastered. Probably not for the low time pilot or
those who don't read the flight manual before flight. My real problem was being
about 5 knots too fast. Proper speed control is critical.

So I'm told. Our club had a member from Long Island, where the club
there had a 1-35. He said they got rid of it after a while because they
got tired of pulling it out of the weeds at the end. Without a landing
flap equipped two seater, they weren't able to train their low time
pilots well enough to land it properly. I think there would be a lot
more acceptance of HP style flaps if we had two seaters to train in.

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Eric Greenwell
Washington State
USA

Wayne Paul wrote:

Here are some pictures of Jim Harper's HP-16:
http://www.soaridaho.com/Schreder/HP...rst_Flight.htm

Wayne
http://www.soaridaho.com/


"Wallace Berry" wrote in message
...

Wayne, what's it like to land an HP in a strong, gusty wind? Do you use
a higher approach speed and only partial flap?
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Eric Greenwell
Washington State
USA

Earlier, JJ wrote:

I rolled in 45 degrees of flaps and
everything looked just about right.
Came over the fence at 50 knots and
waited for her to settle down...

If it's floating down the runway, you just don't have enough flaps
cranked in. Dick Schreder pointed this out when he wrote the
instructions on test flying the HP-11:

http://www.soaridaho.com/Schreder/HP...t_Testing.html

which says:

: If the HP-11 is floating down the
: runway and doesn't want to slow down,
: you just don't have enough flap
: cranked down.

That was in 1963, and I'm pretty sure that it still applies. The same
advice is also repeated in the test flight instructions for the HP-14
and HP-18.

When flying my HP-11 at Air Sailing when the wind favored 21 I
generally stopped right in front of the windmill near the
intersection. Just as I cross the edge of the sage along runway 17 I
would crank on the full 90, flare across 17, and come to a halt within
less than 100 yards of touchdown. And that's landing downhill in a
ship equipped with a go-kart style band-on-tire wheel brake.

The secret to the HP landing technique is to be proactive about
increasing stick forward pressure as you crank on the flaps. If you
try to be reactive, and wait until you see the airspeed change, you've
already gotten too slow. So the technique that works well is to get
the stick moving in the right direction as you crank the flaps on or
off, and worry about refining the speed control later. Control system
engineers call this a "feed forward" system, since there's just not
time to wait for feedback before starting corrective action.

As far as getting sucked into a cloud, the only time it happened to me
it was scary, but other than that rather tame. I cranked on about 75
degrees of flaps, put out the wheel to silence the warning buzzer, and
trundled out the bottom in a 45-degree dive at about 50 knots. The
important thing is to get the flaps out before you exceed the Vfe
speeds.

On another branch of this thread, Eric observes that one reason that
flaps are an issue is that there are so few two-seaters with 90-degree
flaps. I agree; this is one of the primary reasons that the next HP
kit will not be developed with 90-degree flaps. If anybody really
wants one, I can set the wings up for it, but the primary
configuration will have airbrakes. Personally, I really do prefer the
flaps over airbrakes. However, I do not have the resources to
prosecute an ideological battle on their behalf. If anybody wants to
know the depth to which I've sold out in pursuit of a successful
career as a sailplane developer, feel free to let this be the measure
of it.

Thanks, and best regards to all

Bob K.
http://www.hpaircraft.com/hp-24

Eric Greenwell wrote:

JJ Sinclair wrote:

OK, It's winter time and I'm bored, so let me throw my 2 cents in here. The
only flight I ever had in a ship with flaps only was in a PIK-20B. It was a
test flight after a broken fuselage. Things went well until it got time to
land. I rolled in 45 degrees of flaps and everything looked just about right.
Came over the fence at 50 knots and waited for her to settle down. I waited and
waited and waited. By now I had floated down most of the 4000 foot runway and
I'm still floating about 1 foot off the ground. What do I do? Musn't dump the
flaps or she will drop like a stone, right? Finally got the wheel on the ground
and jumped on the brake.
That night I read the flight manual and it said to slowely crank off the flaps
in this situation. I think the flaps only ships are OK, but require a different
set of skills that must be mastered. Probably not for the low time pilot or
those who don't read the flight manual before flight. My real problem was being
about 5 knots too fast. Proper speed control is critical.

So I'm told. Our club had a member from Long Island, where the club
there had a 1-35. He said they got rid of it after a while because they
got tired of pulling it out of the weeds at the end. Without a landing
flap equipped two seater, they weren't able to train their low time
pilots well enough to land it properly. I think there would be a lot
more acceptance of HP style flaps if we had two seaters to train in.


Flaps only ships are very rare in France and kowledge about their handling
is probably even more rare. I wonder how one can handle in such a ship what
is described in our flight Bible, the "blue book" (Manuel du pilote Vol a Voile,
i.e. glider pilot's manual) as the 3 most common mistakes when landing:
1) flare to high; 2) flare with excessive back stick action; 3) bounce.
In this 3 cases the glider comes a few feet above the ground at a speed
just marginally above stall speed and quickly decaying due to the drag of
open airbrakes. The immediate action to avoid that the glider falls on
the ground like a stone in the following seconds is to retract the air-brakes,
so that the drag stops killing your speed and you regain some lift, then
try to land better ahead. But what can you do with no air-brakes?

Bob Kuykendall wrote:

On another branch of this thread, Eric observes that one reason that
flaps are an issue is that there are so few two-seaters with 90-degree
flaps. I agree; this is one of the primary reasons that the next HP
kit will not be developed with 90-degree flaps. If anybody really
wants one, I can set the wings up for it, but the primary
configuration will have airbrakes. Personally, I really do prefer the
flaps over airbrakes. However, I do not have the resources to
prosecute an ideological battle on their behalf. If anybody wants to
know the depth to which I've sold out in pursuit of a successful
career as a sailplane developer, feel free to let this be the measure
of it.

Are there engineering or manufacturing issues that make spoilers a more
desirable choice these days? For example, a fiberglass wing might be
more flexible than a metal one, which would make a 90 degree flap harder
to implement. The early ASW 20 had problems this way with it's 60 degree
flap setting.

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Eric Greenwell
Washington State
USA

"Robert Ehrlich" wrote in message
...
Eric Greenwell wrote:

JJ Sinclair wrote:

OK, It's winter time and I'm bored, so let me throw my 2 cents in
here. The
only flight I ever had in a ship with flaps only was in a PIK-20B. It
was a
test flight after a broken fuselage. Things went well until it got
time to
land. I rolled in 45 degrees of flaps and everything looked just about
right.
Came over the fence at 50 knots and waited for her to settle down. I
waited and
waited and waited. By now I had floated down most of the 4000 foot
runway and
I'm still floating about 1 foot off the ground. What do I do? Musn't
dump the
flaps or she will drop like a stone, right? Finally got the wheel on
the ground
and jumped on the brake.
That night I read the flight manual and it said to slowely crank off
the flaps
in this situation. I think the flaps only ships are OK, but require a
different
set of skills that must be mastered. Probably not for the low time
pilot or
those who don't read the flight manual before flight. My real problem
was being
about 5 knots too fast. Proper speed control is critical.

So I'm told. Our club had a member from Long Island, where the club
there had a 1-35. He said they got rid of it after a while because they
got tired of pulling it out of the weeds at the end. Without a landing
flap equipped two seater, they weren't able to train their low time
pilots well enough to land it properly. I think there would be a lot
more acceptance of HP style flaps if we had two seaters to train in.


Flaps only ships are very rare in France and kowledge about their handling
is probably even more rare. I wonder how one can handle in such a ship
what
is described in our flight Bible, the "blue book" (Manuel du pilote Vol a
Voile,
i.e. glider pilot's manual) as the 3 most common mistakes when landing:
1) flare to high; 2) flare with excessive back stick action; 3) bounce.
In this 3 cases the glider comes a few feet above the ground at a speed
just marginally above stall speed and quickly decaying due to the drag of
open airbrakes. The immediate action to avoid that the glider falls on
the ground like a stone in the following seconds is to retract the
air-brakes,
so that the drag stops killing your speed and you regain some lift, then
try to land better ahead. But what can you do with no air-brakes?

The landing is executed in a way as not to use full 90 degree flap in the
final stages of the final. Rather manage the final approach in a way that
allows the use of less flap. You will have some flap action in reserve to
arrest any excessive sink, similar to using only partial spoiler.

In Fact, when looking at my flying style with the flap only glider,
I use the flap, like you would use the spoiler. I constantly make use of
them
during the pattern to place my self at any point I would like to be.
When making misjudgements it is no different to correct them, as with
spoilered gliders.

It is best for a newcomer to place the glider relative high on final
crank in full flaps and aim for the beginning of the run way.
That way you will have enough speed for corrections if you make a
misjudgement and if you are on glide path you burn of all the energy very
quickly. It really does not matter if you use and extra 200 feet.
In the end it the touch down speed that counts.

As for out landings into small fields with high obstacle, it requires
different approaches and only practice at your home field will make you
proficient.

Udo

"Robert Ehrlich" wrote in message
...
Eric Greenwell wrote:

JJ Sinclair wrote:

OK, It's winter time and I'm bored, so let me throw my 2 cents in
here. The
only flight I ever had in a ship with flaps only was in a PIK-20B. It
was a
test flight after a broken fuselage. Things went well until it got
time to
land. I rolled in 45 degrees of flaps and everything looked just about
right.
Came over the fence at 50 knots and waited for her to settle down. I
waited and
waited and waited. By now I had floated down most of the 4000 foot
runway and
I'm still floating about 1 foot off the ground. What do I do? Musn't
dump the
flaps or she will drop like a stone, right? Finally got the wheel on
the ground
and jumped on the brake.
That night I read the flight manual and it said to slowely crank off
the flaps
in this situation. I think the flaps only ships are OK, but require a
different
set of skills that must be mastered. Probably not for the low time
pilot or
those who don't read the flight manual before flight. My real problem
was being
about 5 knots too fast. Proper speed control is critical.

So I'm told. Our club had a member from Long Island, where the club
there had a 1-35. He said they got rid of it after a while because they
got tired of pulling it out of the weeds at the end. Without a landing
flap equipped two seater, they weren't able to train their low time
pilots well enough to land it properly. I think there would be a lot
more acceptance of HP style flaps if we had two seaters to train in.


Flaps only ships are very rare in France and kowledge about their handling
is probably even more rare. I wonder how one can handle in such a ship
what
is described in our flight Bible, the "blue book" (Manuel du pilote Vol a
Voile,
i.e. glider pilot's manual) as the 3 most common mistakes when landing:
1) flare to high; 2) flare with excessive back stick action; 3) bounce.
In this 3 cases the glider comes a few feet above the ground at a speed
just marginally above stall speed and quickly decaying due to the drag of
open airbrakes. The immediate action to avoid that the glider falls on
the ground like a stone in the following seconds is to retract the
air-brakes,
so that the drag stops killing your speed and you regain some lift, then
try to land better ahead. But what can you do with no air-brakes?

Flaps, once deflected beyond about 10 degrees, produce mainly drag. In
steady-state glides, drag is drag whether produced by flaps or spoilers.
For a given amount of drag, a flapped glider will have the nose much further
down than a glider with spoilers, however. This gives a much better view of
the runway.

The main difference is in the transients as the drag devices are extended or
retracted. The trick with flaps is to manage the transients. Yanking on
flaps from the retracted position will produce a upward transient before the
drag steepens the glide path. Yanking on spoilers will produce a downward
transient before the glider settles into a steeper glide. This generally
means that the pilot should not make large, sudden changes in flap settings
near the ground - but this is good advice for spoilers as well.

Large flap deflections change the relationship between pitch and airspeed.
Large changes in pitch result in small changes in airspeed so that the nose
can be steeply down and the airspeed will not increase much. This invites
the technique popular with HP glider pilots of just aiming the glider
steeply down at the flair point with 90 degrees of flap deployed. If the
glide appears to be overshooting the aim point, pushing the nose further
down steepens the glide without much increase in airspeed. If it appears
that you are undershooting, just raise the nose a little and shallow the
glide. Extremely accurate landings are possible with no changes made in the
flap setting.

The height to start the flare is a bit tricky to judge at first and the
flare is greatly exaggerated compared to spoiler only gliders. If you flare
too high, the recovery is to just relax some of the back stick and let the
glider settle before completing the flare. "Leave 'em where they are" is
good advice when landing with flaps.

I really like flaps. They eliminate the discontinuity in the upper wing
surface created by the spoiler box. Once mastered, they permit much lower
energy landings than with spoilers.

A for as a trainer, the IS28b2 Lark can be landed with flaps only although
the glide is quite shallow. I looked at the flap drive geometry on my Lark
with the thought that it might be modified to allow 45 degrees or more of
positive flap just for training scenarios. It would be possible but the
paperwork would be a nightmare.

Bill Daniels

"Robert Ehrlich" wrote...
Flaps only ships are very rare in France and kowledge about their handling
is probably even more rare. I wonder how one can handle in such a ship
what
is described in our flight Bible, the "blue book" (Manuel du pilote Vol a
Voile,
i.e. glider pilot's manual) as the 3 most common mistakes when landing:
1) flare to high; 2) flare with excessive back stick action; 3) bounce.
In this 3 cases the glider comes a few feet above the ground at a speed
just marginally above stall speed and quickly decaying due to the drag of
open airbrakes. The immediate action to avoid that the glider falls on
the ground like a stone in the following seconds is to retract the
air-brakes,
so that the drag stops killing your speed and you regain some lift, then
try to land better ahead. But what can you do with no air-brakes?

Speed control is important in gracefully landing flaps-only gliders
(spoilers-only too, of course). What I've found - and often seen - is that
gliders' large-deflection flaps essentially 'quit working' as drag producing
devices if landed 'too fast.' True even for HP-16's. Come in too fast and
you _will_ float a long ways in flapped gliders...unless you slowly ease off
on the flaps, in which case the ship will gently settle...sort of the
flaps-only equivalent of easing on more spoilers if running out of field.
Certainly not a Big Deal if understood beforehand.

BTW, the most common mistake I've seen in flapped ships IS landing too
fast...probably fallout from: 1) (U.S. centric) training in Schweizer 2-33's
in which being too fast doesn't generally lead to landing alarm/excitement;
and 2) (worldwide?) training in reasonably benign (in the touchdown sense)
spoilers-only, nose-dragging trainers lacking a springy nosewheel. G-103's
in the U.S. often tell the tale of what bad can happen when trying to force
one of them on the ground at too fast a speed (PIO/fuselage damage/etc.).

Regarding your specific questions, in the event someone DOES manage to flare
too high (whether from doing a good flare but too high, or from
over-aggressive aft-stick motion/'ballooning', or simply bounces the
touchdown) in a flaps-only ship, the only proper recourse is to wait. If
you're savvy enough and have time, you can re-establish the proper pitch
angle for touchdown _then_ wait...but wait. Don't churn the stick and don't
adjust the flap position. The bad news is drag IS high and ground-effect
DOES hugely lessen as speed decays. The good news is there is usually a LOT
of downwash, even on a truly botched flare with full flaps, and it's not the
easiest thing to do to drop a flapped ship in from 3 feet. Certainly no
more difficult IMHO than doing so in a spoilers-only ship. Dropping in
either configuration is possible, of course.

IMHO, about the only situation I can envision where a flaps-only ship IS
worse than a spoilers-only one is that of getting low and slow on the
approach. Is there a spoilers-only driver alive who doesn't take some
comfort in the thought s/he can slam the spoilers shut in that situation and
not distinctly improve things in the near-term future? Get yourself in that
situation in a flaps-only ship and you're essentially out of options. The
GOOD news is that you're much more likely to get low and slow in a ship
having weak landing aids...generally not a problem in gliders having _only_
large deflection flaps as landing aids.

Regards,
Bob W.


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