automated flap setting

A prototype automated flap system was mentioned in the recent Duckhawk
discussion.

My question: Given that our manual flap settings cannot be optimal, how
much real-world improvement in climb and cruise could be gained with an
automated flap system that always has the flaps at their optimal
position ( a hypothetical "perfect" flap setter)?

--- news://freenews.netfront.net/ - complaints: ---

I think the idea is to use auto flap for dynamic soaring. The work load of
flying in a sine wave pattern, and high g forces, is already going to be
intense. Adding the work load of continually changing flap settings
manually might just be too hard to do.


Cookie


At 15:23 11 November 2013, Wallace Berry wrote:
A prototype automated flap system was mentioned in the recent Duckhawk
discussion.

My question: Given that our manual flap settings cannot be optimal, how
much real-world improvement in climb and cruise could be gained with an
automated flap system that always has the flaps at their optimal
position ( a hypothetical "perfect" flap setter)?

--- news://freenews.netfront.net/ - complaints: ---

In article ,
Bob Cook wrote:

I think the idea is to use auto flap for dynamic soaring. The work load of
flying in a sine wave pattern, and high g forces, is already going to be
intense. Adding the work load of continually changing flap settings
manually might just be too hard to do.


Cookie


Yes, much too hard. Even in regular soaring flight it would be too much
if one were to try to manually keep the flaps in the exact best position
for all speeds and angles of attack. The flaps would never stop moving.

My 301 Libelle got no stinkin' modern airfoil. It gots lots of little
detents for the flap handle, but I think only a few matter. Whatever, I
just like a day when I can push all the little levers forward...

--- news://freenews.netfront.net/ - complaints: ---

On Monday, November 11, 2013 10:23:46 AM UTC-5, WB wrote:
A prototype automated flap system was mentioned in the recent Duckhawk discussion. My question: Given that our manual flap settings cannot be optimal, how much real-world improvement in climb and cruise could be gained with an automated flap system that always has the flaps at their optimal position ( a hypothetical "perfect" flap setter)? --- news://freenews.netfront.net/ - complaints: ---

Most current flapped gliders are fairly tolerant of errors in flap setting.
The challange with automating flap settings, other than the relatively simple glide portion of the flight, is that the flap change quite likely needs to lead the change in lift coefficient. It also would need to have some serious filtering to take out gust effects. Add to this a need to not overdo changes to avoid running the power source down.
Sounds like a very complex project with a marginal benefit, especially when applied to gliders with tolerant airfoils.
Then again, thinking back to my PIK-20, it would have been useful. I wore myself out keeping the flaps in the optimum position for the required lift coefficient.
Thank goodness for modern airfoils.
Musing
UH

Didn't Will Scheumann do this in the 70s? I remember a soaring cover photo with a weird sort of mortocycle grip on the stick. As I remember, the basic idea was that the pilot pretty much flew by flaps, changing flap setting to induce changes in CL, with the tail functioning as trimmer.

Now if the windward guys really want to get fancy... you can in principle extract a lot of energy from the air by dynamic soaring the small bits of positive and negative g we run in to all the time. Humans are too slow, and we don't have the feedback we need, which is knowing when the lift vector has a component in the direction of motion to pull, and a component in the opposite direction when you push. This could be automated, lots of little fast pitch motions. Purists laugh, but if you get 60:1 glides out of 15 meter with high speed automated pitch motions, they'll laugh all the way to the back of the scoresheet. Or, I guess, to the annual rules poll to get it banned...

John Cochrane

On Monday, November 11, 2013 12:36:33 PM UTC-8, wrote:
Didn't Will Scheumann do this in the 70s? I remember a soaring cover photo with a weird sort of mortocycle grip on the stick. As I remember, the basic idea was that the pilot pretty much flew by flaps, changing flap setting to induce changes in CL, with the tail functioning as trimmer.



Now if the windward guys really want to get fancy... you can in principle extract a lot of energy from the air by dynamic soaring the small bits of positive and negative g we run in to all the time. Humans are too slow, and we don't have the feedback we need, which is knowing when the lift vector has a component in the direction of motion to pull, and a component in the opposite direction when you push. This could be automated, lots of little fast pitch motions. Purists laugh, but if you get 60:1 glides out of 15 meter with high speed automated pitch motions, they'll laugh all the way to the back of the scoresheet. Or, I guess, to the annual rules poll to get it banned...



John Cochrane

It all needs to be balanced. We learned a couple of decades ago that doing a lot of hard maneuvering generates more induced and separation drag that it gains in energy extracted from the atmosphere which is why no one does big, sharp zoomies into lift anymore - or if they do they pay a heavy price in glide performance. I suspect it is also why you need a pretty sharp gradient for dynamic soaring to work so you don't lose more energy than you gain pulling all those Gs.

In terms of optimal flap setting, I suspect the gains are small unless you are prone to go long distances with the flaps set wrong (I admit occasionally set off on cruise in thermalling flap - oops!). I don't think setting them dynamically would make a ton of difference since you are ill-advised to make that sharp a change in attitude in the first place. If I were designing an automated flap system I'd put a low-pass filter on the inputs with a big (several seconds) time constant.

If I remember correctly, Wil had an ASW-12 that somehow used the flap handle to set pitch attitude at cruise. It was a different era so I don't know that the lessons would apply to today's designs.

9B

wrote, On 11/11/2013 1:21 PM:
It all needs to be balanced. We learned a couple of decades ago that
doing a lot of hard maneuvering generates more induced and separation
drag that it gains in energy extracted from the atmosphere which is
why no one does big, sharp zoomies into lift anymore - or if they do
they pay a heavy price in glide performance. I suspect it is also why
you need a pretty sharp gradient for dynamic soaring to work so you
don't lose more energy than you gain pulling all those Gs.

Even back then (late 80s), some gliders were noticeably less affected
than others; eg, the ASW 20 B/C versus the Ventus. Modern airfoils are
even more tolerant than those of the ASW 20.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)

In article ,
wrote:

Didn't Will Scheumann do this in the 70s? I remember a soaring cover photo
with a weird sort of mortocycle grip on the stick. As I remember, the basic
idea was that the pilot pretty much flew by flaps, changing flap setting to
induce changes in CL, with the tail functioning as trimmer.

Now if the windward guys really want to get fancy... you can in principle
extract a lot of energy from the air by dynamic soaring the small bits of
positive and negative g we run in to all the time. Humans are too slow, and
we don't have the feedback we need, which is knowing when the lift vector has
a component in the direction of motion to pull, and a component in the
opposite direction when you push. This could be automated, lots of little
fast pitch motions. Purists laugh, but if you get 60:1 glides out of 15 meter
with high speed automated pitch motions, they'll laugh all the way to the
back of the scoresheet. Or, I guess, to the annual rules poll to get it
banned...

John Cochrane


Kinda makes me queasy to think about "...lots of little fast pitch
motions."!

The mind boggles at what could be done with continually variable span,
sweep and airfoil with appropriate air data (including remote sensing of
air movement) and enough computing power/software to make sense of it.

I seem to remember a scifi story about a plane that could extract thrust
and lift from all the small scale motion of the air. The engine was shut
down in cruise and the airplane just flew along leaving the air slightly
cooler behind it.

--- news://freenews.netfront.net/ - complaints: ---

Hey Dr. WB: That article about leaving the air cooler was in an April issue of "Flying" magazine, written, I think, by their technical editor, Peter Garrison. Key here is the "April" edition. That article could be related to the "inventions" we see coming out of Ridge Soaring in early April of each year...

:-)

Ray Lovinggood
Carrboro

Wouldn't powered flaps that could respond fast enough to extract energy from gusts fit in the same category as powered boundary layer suction and be illegal per FAI racing rules?

Kirk
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