PDA

View Full Version : negative flaps--what speeds?


303pilot
July 24th 03, 07:03 PM
The manual for my 303 Mosquito is silent as to when the use of negative
flaps becomes beneficial during cruise. Any pointers as to what speeds are
associated with -1 and -2 flap positions? Any data on the LD benefits of
negative flaps at higher speeds?

I read Dick Johnson's flight eval (Aug '79) and my take away is that it
makes sense to go to -1 (4.6 degrees) at around 80 kts and that there's
little difference between -1 and -2. I also understood that article to say
that the speed of best LD could be increased by 5 kts by using -1. Is my
understanding on these two points correct? Dick says the weather was poor
and there was a lot of scatter in the data--does anyone have experience that
agrees/disagrees with Johnson's report?

Any help appreciated--specific to the 303 or regarding flap use during
cruise in general. Hey, I'm transitioning from a PW5 to a 15M and it's got
a lot of new thingies to get used to--retractable wheel, flaps, water,
LEGS!!! ;-)

Brent

Udo Rumpf
July 24th 03, 09:31 PM
I would recommend a flap setting for the FX 67 170 of
-4 deg. starting at ~50 kt and changing over to - 8 at 70-75 Kt.
The Airfoil analysis agrees with the R.Johnson statement,
the L/D is better with -4 Flap
Udo

"303pilot" <brentUNDERSCOREsullivanATbmcDOTcom> wrote in message ...
> The manual for my 303 Mosquito is silent as to when the use of negative
> flaps becomes beneficial during cruise. Any pointers as to what speeds are
> associated with -1 and -2 flap positions? Any data on the LD benefits of
> negative flaps at higher speeds?
>
> I read Dick Johnson's flight eval (Aug '79) and my take away is that it
> makes sense to go to -1 (4.6 degrees) at around 80 kts and that there's
> little difference between -1 and -2. I also understood that article to say
> that the speed of best LD could be increased by 5 kts by using -1. Is my
> understanding on these two points correct? Dick says the weather was poor
> and there was a lot of scatter in the data--does anyone have experience that
> agrees/disagrees with Johnson's report?
>
> Any help appreciated--specific to the 303 or regarding flap use during
> cruise in general. Hey, I'm transitioning from a PW5 to a 15M and it's got
> a lot of new thingies to get used to--retractable wheel, flaps, water,
> LEGS!!! ;-)
>
> Brent
>
>

Dave Martin
July 25th 03, 01:04 AM
At 18:36 24 July 2003, 303pilot wrote:
>The manual for my 303 Mosquito is silent as to when
>the use of negative
>Hi Brent

I am a Mosquito owner.
I have found that normal thermalling is best done at
around the 45-50kt range with +1 flap. I have flown
in weak wave where at around 50knots the glider was
sinking and putting the flaps up to 0 enabled the glider
to climb. The drag is obviously less in the higher
(up) flap setting

When cruising I put the flaps in whatever position
feels comfortable with little reference to the ASI,
other than to monitor the chosen cruise speed. The
way to do this is quite simple, once you start to increase
speed move the flap lever into the free position and
without letting go, let it float. You will find that
it adopts a set position which can be felt, for a given
speed, then you can drop it into the closest notch.
After a while this becomes automatic.

Two other simple techniques are

1. When leaving a thermal put the flaps right up
before you accelerate, on some gliders like the ASW20
putting the flaps up causes a quite marked speed increase,
the Mosquito is not quite so marked and need a little
help from the stick. One you have reached your chosen
cruise speed you can then reset the flaps as required.

2. Only put the flaps down when you have slowed after
your pull up into the next thermal.

This means you are accelerating and decelerating with
minimum drag and do not have to worry about the speed
settings as you speed up and slow down.

Landing the Mosquito is a whole new ball game!! The
was a thread running a few months ago on this subject.

Hope this helps

Dave Martin
>
>

iPilot
July 25th 03, 08:48 AM
Someone (I do not remember the name) wrote in last years Soaring magazine about quite contrary
approach (not related to specific glider). The idea was that one has to put flaps down WHILE slowing
down, not after. And the reasoning was that flap position is not that much depending on the speed of
the glider, but on angle of attack. So if one attacks thermals aggressively making serious pull-ups,
the increased AOA means one has to advance in flap settings beforehand the lowering speeds. Same
applies to leaving the thermal cause then the AOA decreases. It was told to be making huge
differences.


Regards,
Kaido, who doesn't fly flapped gliders currently.


>
> 2. Only put the flaps down when you have slowed after
> your pull up into the next thermal.
>
> This means you are accelerating and decelerating with
> minimum drag and do not have to worry about the speed
> settings as you speed up and slow down.
>

iPilot
July 25th 03, 08:53 AM
Sorry, It was in 2001, but I still don't remember the specific article and the writer.


"iPilot" > wrote in message ...
> Someone (I do not remember the name) wrote in last years Soaring magazine about quite contrary
> approach (not related to specific glider). The idea was that one has to put flaps down WHILE
slowing
> down, not after. And the reasoning was that flap position is not that much depending on the speed
of
> the glider, but on angle of attack. So if one attacks thermals aggressively making serious
pull-ups,
> the increased AOA means one has to advance in flap settings beforehand the lowering speeds. Same
> applies to leaving the thermal cause then the AOA decreases. It was told to be making huge
> differences.
>
>
> Regards,
> Kaido, who doesn't fly flapped gliders currently.
>
>
> >
> > 2. Only put the flaps down when you have slowed after
> > your pull up into the next thermal.
> >
> > This means you are accelerating and decelerating with
> > minimum drag and do not have to worry about the speed
> > settings as you speed up and slow down.
> >
>
>

Dave Martin
July 25th 03, 10:23 AM
Kaido

Read, 'Advance Cross Country Soaring' by John Delafield.
Pages 81 Flaps

John gives a detailed account of the use of flaps,
which agrees with what I said, or more to the point,
there were few articles written on the correct use
of flaps in 1983 and the information from John helped
me learn how to use the flaps.

In summary he says, 'Flaps should be not be regarded
as anything other than an auxilary control to enable
the pilot to operate the wing efficiently throughout
the speed range. The are straight forward in use and
will become instinctive after only a few hours' practice.'

The method described is simple and reduces the movements
to a minimum and saves the pilot worrying what the
next setting should be.

Flaps UP to slow down. Flaps UP to accelerate, then
once the
required speed has been achieved set them to support
flight at that speed.

The only word of caution is that in large pull ups
and push overs with reduced G at the top and increased
stall speed because of the negative flap setting the
pilot may be in serious danger of spinning.



At 08:24 25 July 2003, Ipilot wrote:
>Someone (I do not remember the name) wrote in last
>years Soaring magazine about quite contrary
>approach (not related to specific glider). The idea
>was that one has to put flaps down WHILE slowing
>down, not after. And the reasoning was that flap position
>is not that much depending on the speed of
>the glider, but on angle of attack. So if one attacks
>thermals aggressively making serious pull-ups,
>the increased AOA means one has to advance in flap
>settings beforehand the lowering speeds. Same
>applies to leaving the thermal cause then the AOA decreases.
>It was told to be making huge
>differences.
>
>
>Regards,
>Kaido, who doesn't fly flapped gliders currently.
>
>
>>
>> 2. Only put the flaps down when you have slowed after
>> your pull up into the next thermal.
>>
>> This means you are accelerating and decelerating with
>> minimum drag and do not have to worry about the speed
>> settings as you speed up and slow down.
>>
>
>
>

303pilot
July 25th 03, 04:43 PM
Thanks all and I'm interested in any other opinions/data.

"Robert Ehrlich" > wrote in message
...
> justification. The appropriate setting should be derived
> from the various polars corresponding to the various settings.
This is what I was trying to do with the three polars in Dick Johnson's
flight eval--the problem is that the weather wasn't optimal, producing a lot
of scatter in the polar curves.

Dave Martin
July 25th 03, 04:53 PM
Whilst all this theory makes sense ---- to some, my
glider manual only has the single polar curve which
itself is a guestimate from a comparison flight with
a 16 metre Standard Cirrus B

I like to keep my flying simple, John Delafields method
works it is simple and in flight uncomplicated. I
suspect the savings on drag produced by speeding up
or slowing down with flaps in a negative, up, position
is relatively small.

Whereas putting flaps down at speed to slow down appears
very inefficient.

Still if you are happy with this loss of energy then
fine.

Dave Martin

Bob Kuykendall
July 25th 03, 06:01 PM
Robert raises some good points about interpolating between the
different polars, and it points towards a question that I've been
wondering for a while:

Why have none of the established manufacturers come out with an
auto-flap system that uses a computer to assess several parameters
(speed, angle of attack, G loading, air density, etc), and an actuator
to adjust the flaps to an appropriate setting?

I suspect that the answer might be, because it really doesn't matter
all that much. Look at the difference between the LS6 and the LS8 -
you can barely tell them apart until you get to about 85 knots.

However, that autoflap arrangement has a lot of whiz-bang appeal, and
I'd like to see someone give it a try.

Thanks, and best regards

Bob K.
http://www.hpaircraft.com

Bruce Hoult
July 25th 03, 09:43 PM
In article >,
Robert Ehrlich > wrote:

> If you consider
> two polars, e.g. for zero setting and the first negative setting,
> they intersect each other at some point. At speed above the
> speed of this point, clearly the negative setting is better,
> at speed below this point, the zero setting is better. But it
> is not optimal to switch the setting juste when you cross this
> speed. Above the intersection, the two polars have a common
> tangent which meets each polar at some point, corresponding
> to some speed, a low one for zero setting and a high one
> for negative setting. You should never fly a speed between these
> both speed

Another alternative is to use a flap setting between the detents while
in that speed range.

The performance difference is likely to be minor in any case.

When I fly the Janus -- the only flapped ship I fly, and which (as you
note) gives individual polars in the manual -- I tend to choose between
the lower and higher flap setting based on what I and the air are likely
to be doing. For example, when flying in the 50 - 60 knot range, if the
air is smooth (e.g. in wave) I'll fly in zero flap. If the air is bumpy
and I'm turning from side to side looking for a thermal then I'll use +6
becasue I figure that the better response and performance at the higher
AOA in a gust will outweigh the little extra drag the rest of the time.

At the other end, it was I think the Dick Johnson report that claimed
that there was no speed range in which -4 was better than both 0 and -7,
so don't use it.

-- Bruce

Mike Borgelt
July 26th 03, 02:59 AM
On 25 Jul 2003 10:01:38 -0700, (Bob Kuykendall)
wrote:

>Robert raises some good points about interpolating between the
>different polars, and it points towards a question that I've been
>wondering for a while:
>
>Why have none of the established manufacturers come out with an
>auto-flap system that uses a computer to assess several parameters
>(speed, angle of attack, G loading, air density, etc), and an actuator
>to adjust the flaps to an appropriate setting?
>
>I suspect that the answer might be, because it really doesn't matter
>all that much. Look at the difference between the LS6 and the LS8 -
>you can barely tell them apart until you get to about 85 knots.
>
>However, that autoflap arrangement has a lot of whiz-bang appeal, and
>I'd like to see someone give it a try.
>
>Thanks, and best regards
>
>Bob K.
>http://www.hpaircraft.com


Bob,
You don't need a computer. About 20 years ago the Akaflieg
Braunschweig had an auto flap sustem in an LS3. Essentially a weight
on an arm - more g more flapdown. Less g and the faster you go the
airloads push the flap up more. Do this correctly and it all works
nicely I'm told. You do need a damper as you are un mass balancing the
flaps and might be prone to flutter.

The flaps on the LS6 barely work according to the DLR polar I have
which is of course why the LS8 works so well.

Mike Borgelt

Andreas Maurer
July 26th 03, 02:30 PM
On Fri, 25 Jul 2003 14:31:35 +0200, "Bert Willing"
> wrote:

>Flaps are just a pitch control which is more direct than the stick. I do
>accelerate by pushing the flaps to negativ, and I deccelerate by pulling
>them to positive settings. Works very nicely (but still using the stick :-)
>I don't see why I should use negativ flaps to pull up.

Yup. Always keep the AoA constant by using the flaps.
I think the procedure that is described in the ASW-20's manual
describes the physics very well.

Bye
Andreas

Dave Martin
July 26th 03, 06:50 PM
Andreas,

Without wanting to prolong the argument
There appear to be two ways of achieving the same objective,
pilots should just chose the one they are happy with.
I trust the John Delafield theory and find it works,
others prefer yours and Berts

Dave
14:06 26 July 2003, Andreas Maurer wrote:
>On Fri, 25 Jul 2003 14:31:35 +0200, 'Bert Willing'
> wrote:
>
>>Flaps are just a pitch control which is more direct
>>than the stick. I do
>>accelerate by pushing the flaps to negativ, and I deccelerate
>>by pulling
>>them to positive settings. Works very nicely (but still
>>using the stick :-)
>>I don't see why I should use negativ flaps to pull
>>up.
>
>Yup. Always keep the AoA constant by using the flaps.
>I think the procedure that is described in the ASW-20's
>manual
>describes the physics very well.
>
>Bye
>Andreas
>

Kirk Stant
July 26th 03, 07:14 PM
Dave Martin > wrote in message >
> Kirk invited comments -- obviously an aerotow man.

A man of all tastes - I have winch launched (in Germany) and would do
it if available out here, but in the US aerotow is more common. I'm
also a tow pilot, so have seen it from both ends.

>
> Kirk try this in your machine at height I suggest several
> thousand feet.
>
> Fly at 60 knots and then pull hard back to about 45
> degrees climb attitude, as the speed decays push hard
> forwards, as you attain straight and level flight turn
> quickly left or right . If you do it correctly you
> can enter a spin nicely, IN any machine!!!!!!!

Interesting maneuver. Sounds like a rolling departure - which would
take some real mishandling of the glider to do! I also so some
aerobatics (Grobs, Swifts, Pilatus etc) so I'm a bit familiar with
what a glider will do in unusual attitudes.
>
> It is the classic spin off a winch launch failure.
> Pulling up hard into thermals and pushing hard over
> is no different. As an instructor it requires a
> little practice to make it work every time. Somehow
> students do it with ease

Sounds like you are forcing a negative AOA stall then rolling, causing
an inverted spin from right side up.
>
> If your description of how you pull up is true then
> I will steer clear of you in the sky! May be you were
> just taking the p***
>

Well, In my description I never lose control of my glider, despite a
badly misjudged pullup to well below stall speed - in yours you depart
into a spin! I think I will steer clear of you, too!

> Dave Martin

Cheers,

Kirk

Dave Martin
July 26th 03, 11:56 PM
At 18:48 26 July 2003, Kirk Stant wrote:
>Dave Martin wrote in message >

Kirk

The exercise I described is one of the BGA stall reinforcement
exercises. The common cause following a winch launch
failure, pushing hard forward, then as the attitude
looks correct and as the glider is in a reduced G situation
starting a turn. (Without getting the books out that
is as simple as I can describe it) This has caused
several accidents in the UK some of them fatal.

The danger also exists when pulling up sharply in to
a thermal and pushing over hard at the top of the pull
up then starting a turn in reduced G.

Fingers crossed as yet I have never entered a spin
pulling up into thermals. But as an instructor at
a winch launch site, it something you need to be able
to demonstrate.

But we are getting away from the thread...........

Regards


Dave

Eric Greenwell
July 27th 03, 05:08 AM
In article >,
says...

> The danger also exists when pulling up sharply in to
> a thermal and pushing over hard at the top of the pull
> up then starting a turn in reduced G.

Do people really enter thermals this way? I've never seen anyone do
this. I might pull up at as much as 1.5 g momentarily, but just let it
bleed down to 1 g and start a turn. What is the value in pushing hard
at the top, instead of just entering a turn?
--
!Replace DECIMAL.POINT in my e-mail address with just a . to reply
directly

Eric Greenwell
Richland, WA (USA)

Bill Daniels
July 27th 03, 05:37 AM
"Dave Martin" > wrote in message
...

> The exercise I described is one of the BGA stall reinforcement
> exercises. The common cause following a winch launch
> failure, pushing hard forward, then as the attitude
> looks correct and as the glider is in a reduced G situation
> starting a turn. (Without getting the books out that
> is as simple as I can describe it) This has caused
> several accidents in the UK some of them fatal.
>
> The danger also exists when pulling up sharply in to
> a thermal and pushing over hard at the top of the pull
> up then starting a turn in reduced G.
>
> Fingers crossed as yet I have never entered a spin
> pulling up into thermals. But as an instructor at
> a winch launch site, it something you need to be able
> to demonstrate.
>
> But we are getting away from the thread...........
>
> Regards
>
>
> Dave
>
These are fun maneuvers. I find a Blanik L-23 to be a prefect trainer for
them - it spins easily, recovers easily with little altitude loss or
airspeed gain.

My winch stall maneuver is done at a safe altitude (of course). First, I
ask the student to dive then zoom up at 45 - 50 degrees, then when the
airspeed drops to about 55Kts, I yell "wire break" and expect the student to
push over smartly in a simulated wire break recovery. (This gets the
student used to the attitude and feel of a wire break and the control inputs
needed for a recovery before trying it for real on the winch.)

If the student doesn't screw it up on his own, I will demonstrate a botched
recovery by doing nothing until the nose falls on its own then stopping the
pitch-down at the normal gliding attitude. This results in the airspeed at
about 15 knots with the glider held level with near full-up elevator. The
L-23 will usually oblige with a quick flip into a spin even if no turn is
attempted - try a turn and it will spin for sure. No student observing this
has failed to appreciate that the wings should be level and the nose needs
to be well below the normal glide attitude and held there until a safe
airspeed is achieved.

The thermal entry stall/spin only requires that the pilot hold into-the-turn
rudder a second or two longer than needed while trying to reduce airspeed
still further. In most cases, this is a full cross-controlled accelerated
stall from a 45 degree bank - wheee! (I've caught some high time pilots
with this one.)

Bill Daniels

Bill Daniels
July 27th 03, 05:40 AM
"Eric Greenwell" > wrote in message
.. .
> In article >,
> says...
>
> > The danger also exists when pulling up sharply in to
> > a thermal and pushing over hard at the top of the pull
> > up then starting a turn in reduced G.
>
> Do people really enter thermals this way? I've never seen anyone do
> this. I might pull up at as much as 1.5 g momentarily, but just let it
> bleed down to 1 g and start a turn. What is the value in pushing hard
> at the top, instead of just entering a turn?
> --
> !Replace DECIMAL.POINT in my e-mail address with just a . to reply
> directly
>
> Eric Greenwell
> Richland, WA (USA)

Depends on how long you hold the 1.5G. Hold it long enough and you might
get a steep pitch up that requires forward stick to get the nose down for
the turn. Rush it and things get interesting.

Bill Daniels

Kirk Stant
July 27th 03, 09:47 AM
"Bill Daniels" > wrote in message

> The thermal entry stall/spin only requires that the pilot hold into-the-turn
> rudder a second or two longer than needed while trying to reduce airspeed
> still further. In most cases, this is a full cross-controlled accelerated
> stall from a 45 degree bank - wheee! (I've caught some high time pilots
> with this one.)
>
> Bill Daniels

Interesting exercise. Also sounds like a good way to teach
low-G/low-AOA affects on stall speeds. I can see how it would work
well in something like a Blanik, with a huge elevator. How do
competition ships with small elevators react? I'll have to try with
my LS6, but I have the feeling that the elevator is not powerful
enough to keep the nose from falling through and causing a stall/spin.

On the other hand, in the same nose high/close to stall speed
situation, the LS6 (and any other glider, I'm sure) reacts perfectly
well to an unloaded (low-G) roll in the direction of the intended
turn, followed by an easy nose down acceleration to a safe speed
before pulling on the G necessary for the turn. Not a recommended
normal thermal entry by any means, but a way to recover from a
botched, overenthusiastic zoom-in.

The obvious key is the G (or AOA) versus airspeed relationship.
Trying to turn when the airspeed is down in the teens would show that
the pilot has a certain lack of situational awareness!

Kirk
66

Bill Daniels
July 27th 03, 02:34 PM
"Kirk Stant" > wrote in message
om...
> "Bill Daniels" > wrote in message
>
> > The thermal entry stall/spin only requires that the pilot hold
into-the-turn
> > rudder a second or two longer than needed while trying to reduce
airspeed
> > still further. In most cases, this is a full cross-controlled
accelerated
> > stall from a 45 degree bank - wheee! (I've caught some high time pilots
> > with this one.)
> >
> > Bill Daniels
>
> Interesting exercise. Also sounds like a good way to teach
> low-G/low-AOA affects on stall speeds. I can see how it would work
> well in something like a Blanik, with a huge elevator. How do
> competition ships with small elevators react? I'll have to try with
> my LS6, but I have the feeling that the elevator is not powerful
> enough to keep the nose from falling through and causing a stall/spin.
>
> On the other hand, in the same nose high/close to stall speed
> situation, the LS6 (and any other glider, I'm sure) reacts perfectly
> well to an unloaded (low-G) roll in the direction of the intended
> turn, followed by an easy nose down acceleration to a safe speed
> before pulling on the G necessary for the turn. Not a recommended
> normal thermal entry by any means, but a way to recover from a
> botched, overenthusiastic zoom-in.
>
> The obvious key is the G (or AOA) versus airspeed relationship.
> Trying to turn when the airspeed is down in the teens would show that
> the pilot has a certain lack of situational awareness!
>
> Kirk
> 66

A stall occurs only when the AOA exceeds about 16 degrees for most airfoils.
Low G, by itself, isn't dangerous and, in fact, reduces the stall speed
since the wing isn't loaded. The stalling AOA comes in at the transition
from low G to > one G.

Most competition ships fly with the CG well aft so, even with small
elevators, they have plenty of elevator authority for some interesting
stalls. I do worry that many competition pilots get very close to a
stall/spin departure without realizing it during an aggressive thermal
entry. This is particularly dangerous when down low (I've GOT to center
this thermal or land out.) Desperately and aggressively trying to center a
small core when under the stress of a pending outlanding is a bad
combination - there have been a more than a few bad outcomes to this
situation.

Bill Daniels

Bert Willing
July 28th 03, 08:58 AM
It's been the Akaflieg Munich, and the glider was/is the Mü 28 (single
seater aerobatics).

Bert

"Mike Borgelt" > a écrit dans le message de
...
> On 25 Jul 2003 10:01:38 -0700, (Bob Kuykendall)
> wrote:
>
> >Robert raises some good points about interpolating between the
> >different polars, and it points towards a question that I've been
> >wondering for a while:
> >
> >Why have none of the established manufacturers come out with an
> >auto-flap system that uses a computer to assess several parameters
> >(speed, angle of attack, G loading, air density, etc), and an actuator
> >to adjust the flaps to an appropriate setting?
> >
> >I suspect that the answer might be, because it really doesn't matter
> >all that much. Look at the difference between the LS6 and the LS8 -
> >you can barely tell them apart until you get to about 85 knots.
> >
> >However, that autoflap arrangement has a lot of whiz-bang appeal, and
> >I'd like to see someone give it a try.
> >
> >Thanks, and best regards
> >
> >Bob K.
> >http://www.hpaircraft.com
>
>
> Bob,
> You don't need a computer. About 20 years ago the Akaflieg
> Braunschweig had an auto flap sustem in an LS3. Essentially a weight
> on an arm - more g more flapdown. Less g and the faster you go the
> airloads push the flap up more. Do this correctly and it all works
> nicely I'm told. You do need a damper as you are un mass balancing the
> flaps and might be prone to flutter.
>
> The flaps on the LS6 barely work according to the DLR polar I have
> which is of course why the LS8 works so well.
>
> Mike Borgelt

Mike Borgelt
July 28th 03, 09:58 AM
On Mon, 28 Jul 2003 09:58:51 +0200, "Bert Willing"
> wrote:

>It's been the Akaflieg Munich, and the glider was/is the Mü 28 (single
>seater aerobatics).
>
>Bert
>
You are right it was Munich but they did have an LS3 as well with the
auto flap.

Mike Borgelt

Steve Pawling
July 29th 03, 04:01 AM
The method Dave described is what I normally do in my LS-3a. Yesterday
I was trying some different settings and noticed that at 100 knots,
the flaps could be moved between 0 and -7 with no issues. At 120 knots
the flaps wanted to stay at about -3 and when I moved them to -7,
which required some pressure, it created a humming noise. Seems that
-7 should be better at higher speeds but the noise and pressure on the
flap handle tells me otherwise.

Also, the LS-3a Flight Manual has the following instructions:

Up to 103 knots - Flaps should be between 0 and -7, depending on
desired speed. Once the aircraft is trimmed for thermaling, no
additional trim adjustment is required for high speed flight. Any
stick forces can be removed by adjusting the flap position. This
results in the correct flap position for all speeds.

103 ~ 146 knots - Flap position -7. Stick forces should be reduced to
zero through trim adjustment.

All the best,
Steve

Dave Martin > wrote in message >...

snip
>
> When cruising I put the flaps in whatever position
> feels comfortable with little reference to the ASI,
> other than to monitor the chosen cruise speed. The
> way to do this is quite simple, once you start to increase
> speed move the flap lever into the free position and
> without letting go, let it float. You will find that
> it adopts a set position which can be felt, for a given
> speed, then you can drop it into the closest notch.
> After a while this becomes automatic.
>
snip
>
> Dave Martin
> >
> >

Robert Ehrlich
July 29th 03, 01:23 PM
Andreas Maurer wrote:
> ...
> Yup. Always keep the AoA constant by using the flaps.
> I think the procedure that is described in the ASW-20's manual
> describes the physics very well.

Isn't the attitude rather than the AoA you are keeping constant?
As far as I can say from experience on LS6, it flies with nearly
the same attitude at high speed with negative flaps and at low speeds
with zero or positive flaps, which means that the Aoa (defined as the
angle between the direction of the airflow and the wing chord, i.e.
the line frm leading to (moving) trailing edge) varies.

Robert Ehrlich
July 29th 03, 01:31 PM
Bob Kuykendall wrote:
>
> Robert raises some good points about interpolating between the
> different polars, and it points towards a question that I've been
> wondering for a while:
>
> Why have none of the established manufacturers come out with an
> auto-flap system that uses a computer to assess several parameters
> (speed, angle of attack, G loading, air density, etc), and an actuator
> to adjust the flaps to an appropriate setting?
>

I think one of the reason for not doing that is that it would make the
use of some (probably eletrical) power supply mandatory. I don't know
if it is a part of the certification requirements, but the fact is that
in all gliders, the basic operation is always possible without any such
power. E.g. in France at least only the basic pneumatic instruments are
mandatory, and they must be pneumatic.

Shaber CJ
August 5th 03, 09:26 PM
>The flaps on the LS6 barely work according to the DLR polar I have
>which is of course why the LS8 works so well.
>
>Mike Borgelt

Mike any idea where I can get polar data on the V2C?

Shaber CJ
August 5th 03, 09:32 PM
I have seen a mirror with a level type of device attached to the panel to help
set flap positions, Sean Franke's Ventus has this. I I do not know how it
works but was hoping someone has used sucha device and could comment.

Craig

Google