Slats and Fowler Flaps On Light Plane

Steve Wittman had leading edge FLAPS (not slats) on his Buttercup.
Buttercup is a predecessor to the Wittman Tailwind.
That was back in the early '50s?

Anyway, the idea is to have a thin wing for high speed cruise and
recontour it into an undercambered thin wing to slow down for landing.

Thin airfoils tend to have low CLmax while recurred thin airfoils
can have amazingly high CLmax.

Taken to an extreme, the "sail" type single surfaced ultralight wings
show a CLmax of over 4(!)

Leading edge flaps are always(?) deployed in conjunction with trailing
edge flaps of some kind. Even if it is a simple split flap.

Otherwise, the CP would move way forward, and the chord line suddenly
goes the wrong way.

Earl Luce built the first replica Buttercup (and sells plans fo it too).

Earl said Buttercup lands in the low 40s with the flaps down.
Or over 70 (with a lot of skipping and skating) without them.

I did a little browsing at the NACA server and found a lot of info on
leading edge flaps. But it all seemed more applicable to supersonic and
high subsonic heavies.

To date, Buttercup is the only light plane I know of that has leading
edge flaps.

Richard


Peter Dohm wrote:

Brock wrote:

I feel there is a real advantage to the use of slats and flaps in
order to have things happen slowly during landing and yet still have a
good cruise speed. Of course the problem is in the complexity and the
extra weight. For rails I was thinking about something like standard
kitchen drawer rails or perhaps a tube within a tube design. I
wouldn't think their would be a lot of force on the slat at low
takeoff speeds so the structure wouldn't have to be bullet proof,
their would probably be a lot more force on the flaps though. I
haven't been able to find information if the necessary airplane
hardware is available commercially, perhaps it would have to be custom
made. Any ideas on how to go about building something like this?

Brock

Whereas the Helio Courier and Morane Rallye (among others), and their
slats, are discussed elsewhere in the thread; I'll just mention that all
of the high wing Cessna aircraft with which I am familiar have single
slotted Fowler flaps. I have no idea how much performance you would
gain with double slotted Fowler flaps, and doubt that they would add
much weight; but believe that they would be a real pain in the neck to
build s the dimensions would need to be held closely in order for the
slots to have the correct proportions and the additional surfaces would
need to be finished.

Peter

Many excellent points.

I started to write that I don't know of anything written regarding
leading edge flaps, either. Then decided to try a search on
http://www.dogpile.com/ and I found a reference when I tried flap
(singular) as part of the search argument in leading+edge+flap and got
"Aerodynamic loads on a leading-edge flap and a leading-edge slat on
the NACA 64A101 airfoil section" John A Kelly & George B McCullough
http://naca.larc.gov/reports/1954/na...ca-tn-3220.pdf

Unfortunately, I think you may need to know more about aerodynamics,
and some other things, to design anything really useful from it.
However, it appears intended to compare the characteristics of flaps
vs slats in in great detail; including graphs, sketched, and
tabulations of pressure distribution. And you and print it out.

Peter

By the way, the old Dover Edition of "Theory of Wing Sections" is
still available from various sources, and includes material on both
fixed and moveable slats alone and in combination with trailing
edge flaps. I don't recall whether leading edge flaps are also
discussed, and my copy seems to have hidden behind another book :-(

Richard Lamb wrote:

Steve Wittman had leading edge FLAPS (not slats) on his Buttercup.
Buttercup is a predecessor to the Wittman Tailwind.
That was back in the early '50s?

Anyway, the idea is to have a thin wing for high speed cruise and
recontour it into an undercambered thin wing to slow down for landing.

Thin airfoils tend to have low CLmax while recurred thin airfoils
can have amazingly high CLmax.

Taken to an extreme, the "sail" type single surfaced ultralight wings
show a CLmax of over 4(!)

Leading edge flaps are always(?) deployed in conjunction with trailing
edge flaps of some kind. Even if it is a simple split flap.

Otherwise, the CP would move way forward, and the chord line suddenly
goes the wrong way.

Earl Luce built the first replica Buttercup (and sells plans fo it too).

Earl said Buttercup lands in the low 40s with the flaps down.
Or over 70 (with a lot of skipping and skating) without them.

I did a little browsing at the NACA server and found a lot of info on
leading edge flaps. But it all seemed more applicable to supersonic and
high subsonic heavies.

To date, Buttercup is the only light plane I know of that has leading
edge flaps.

Richard

Peter Dohm wrote:

Brock wrote:

I feel there is a real advantage to the use of slats and flaps in
order to have things happen slowly during landing and yet still have a
good cruise speed. Of course the problem is in the complexity and the
extra weight. For rails I was thinking about something like standard
kitchen drawer rails or perhaps a tube within a tube design. I
wouldn't think their would be a lot of force on the slat at low
takeoff speeds so the structure wouldn't have to be bullet proof,
their would probably be a lot more force on the flaps though. I
haven't been able to find information if the necessary airplane
hardware is available commercially, perhaps it would have to be custom
made. Any ideas on how to go about building something like this?

Brock

Whereas the Helio Courier and Morane Rallye (among others), and their
slats, are discussed elsewhere in the thread; I'll just mention that all
of the high wing Cessna aircraft with which I am familiar have single
slotted Fowler flaps. I have no idea how much performance you would
gain with double slotted Fowler flaps, and doubt that they would add
much weight; but believe that they would be a real pain in the neck to
build s the dimensions would need to be held closely in order for the
slots to have the correct proportions and the additional surfaces would
need to be finished.

Peter

Oooops! I left NASA out of that URL and then forgot to test the
link in the message before I pressed send. The corrected version is:
"Aerodynamic loads on a leading-edge flap and a leading-edge slat on
the NACA 64A101 airfoil section" John A Kelly & George B McCullough
http://naca.larc.nasa.gov/reports/19...ca-tn-3220.pdf

Sorry about that.

Peter

The F-104 had both leading and trailing edge flaps and wing was
'blown'.

Big John
Mach 1+


On Sat, 26 Jul 2003 02:51:21 GMT, Richard Lamb
wrote:

Steve Wittman had leading edge FLAPS (not slats) on his Buttercup.
Buttercup is a predecessor to the Wittman Tailwind.
That was back in the early '50s?

Anyway, the idea is to have a thin wing for high speed cruise and
recontour it into an undercambered thin wing to slow down for landing.

Thin airfoils tend to have low CLmax while recurred thin airfoils
can have amazingly high CLmax.

Taken to an extreme, the "sail" type single surfaced ultralight wings
show a CLmax of over 4(!)

Leading edge flaps are always(?) deployed in conjunction with trailing
edge flaps of some kind. Even if it is a simple split flap.

Otherwise, the CP would move way forward, and the chord line suddenly
goes the wrong way.

Earl Luce built the first replica Buttercup (and sells plans fo it too).

Earl said Buttercup lands in the low 40s with the flaps down.
Or over 70 (with a lot of skipping and skating) without them.

I did a little browsing at the NACA server and found a lot of info on
leading edge flaps. But it all seemed more applicable to supersonic and
high subsonic heavies.

To date, Buttercup is the only light plane I know of that has leading
edge flaps.

Richard


Peter Dohm wrote:

Brock wrote:

I feel there is a real advantage to the use of slats and flaps in
order to have things happen slowly during landing and yet still have a
good cruise speed. Of course the problem is in the complexity and the
extra weight. For rails I was thinking about something like standard
kitchen drawer rails or perhaps a tube within a tube design. I
wouldn't think their would be a lot of force on the slat at low
takeoff speeds so the structure wouldn't have to be bullet proof,
their would probably be a lot more force on the flaps though. I
haven't been able to find information if the necessary airplane
hardware is available commercially, perhaps it would have to be custom
made. Any ideas on how to go about building something like this?

Brock

Whereas the Helio Courier and Morane Rallye (among others), and their
slats, are discussed elsewhere in the thread; I'll just mention that all
of the high wing Cessna aircraft with which I am familiar have single
slotted Fowler flaps. I have no idea how much performance you would
gain with double slotted Fowler flaps, and doubt that they would add
much weight; but believe that they would be a real pain in the neck to
build s the dimensions would need to be held closely in order for the
slots to have the correct proportions and the additional surfaces would
need to be finished.

Peter

One of the NACA Research Memorandum covers what could be the F-104
wing design. Check out "The Effects of Leading Edge Flap Upon
the Lift, Drag, and pitching moment of and airplane employing a
thin, Unswept wing".

It doesn't mention "blowing" the wing, tho.

Richard

Big John wrote:

The F-104 had both leading and trailing edge flaps and wing was
'blown'.

Big John
Mach 1+

On Sat, 26 Jul 2003 02:51:21 GMT, Richard Lamb
wrote:

Steve Wittman had leading edge FLAPS (not slats) on his Buttercup.
Buttercup is a predecessor to the Wittman Tailwind.
That was back in the early '50s?

Anyway, the idea is to have a thin wing for high speed cruise and
recontour it into an undercambered thin wing to slow down for landing.

Thin airfoils tend to have low CLmax while recurred thin airfoils
can have amazingly high CLmax.

Taken to an extreme, the "sail" type single surfaced ultralight wings
show a CLmax of over 4(!)

Leading edge flaps are always(?) deployed in conjunction with trailing
edge flaps of some kind. Even if it is a simple split flap.

Otherwise, the CP would move way forward, and the chord line suddenly
goes the wrong way.

Earl Luce built the first replica Buttercup (and sells plans fo it too).

Earl said Buttercup lands in the low 40s with the flaps down.
Or over 70 (with a lot of skipping and skating) without them.

I did a little browsing at the NACA server and found a lot of info on
leading edge flaps. But it all seemed more applicable to supersonic and
high subsonic heavies.

To date, Buttercup is the only light plane I know of that has leading
edge flaps.

Richard


Peter Dohm wrote:

Brock wrote:

I feel there is a real advantage to the use of slats and flaps in
order to have things happen slowly during landing and yet still have a
good cruise speed. Of course the problem is in the complexity and the
extra weight. For rails I was thinking about something like standard
kitchen drawer rails or perhaps a tube within a tube design. I
wouldn't think their would be a lot of force on the slat at low
takeoff speeds so the structure wouldn't have to be bullet proof,
their would probably be a lot more force on the flaps though. I
haven't been able to find information if the necessary airplane
hardware is available commercially, perhaps it would have to be custom
made. Any ideas on how to go about building something like this?

Brock

Whereas the Helio Courier and Morane Rallye (among others), and their
slats, are discussed elsewhere in the thread; I'll just mention that all
of the high wing Cessna aircraft with which I am familiar have single
slotted Fowler flaps. I have no idea how much performance you would
gain with double slotted Fowler flaps, and doubt that they would add
much weight; but believe that they would be a real pain in the neck to
build s the dimensions would need to be held closely in order for the
slots to have the correct proportions and the additional surfaces would
need to be finished.

Peter

Richard

Bird landed with some power on engine to provide bleed air to wing. We
had some check outs that flared and pulled the throttle to idle while
still in the air and the bird dropped in. Some of these caused damage
to bird.

Go to Google and search for "F-104 blown wing" and see the details.

Big John

On Sat, 26 Jul 2003 20:09:07 GMT, Richard Lamb
wrote:

One of the NACA Research Memorandum covers what could be the F-104
wing design. Check out "The Effects of Leading Edge Flap Upon
the Lift, Drag, and pitching moment of and airplane employing a
thin, Unswept wing".

It doesn't mention "blowing" the wing, tho.

Richard

Big John wrote:

The F-104 had both leading and trailing edge flaps and wing was
'blown'.

Big John
Mach 1+

On Sat, 26 Jul 2003 02:51:21 GMT, Richard Lamb
wrote:

Steve Wittman had leading edge FLAPS (not slats) on his Buttercup.
Buttercup is a predecessor to the Wittman Tailwind.
That was back in the early '50s?

Anyway, the idea is to have a thin wing for high speed cruise and
recontour it into an undercambered thin wing to slow down for landing.

Thin airfoils tend to have low CLmax while recurred thin airfoils
can have amazingly high CLmax.

Taken to an extreme, the "sail" type single surfaced ultralight wings
show a CLmax of over 4(!)

Leading edge flaps are always(?) deployed in conjunction with trailing
edge flaps of some kind. Even if it is a simple split flap.

Otherwise, the CP would move way forward, and the chord line suddenly
goes the wrong way.

Earl Luce built the first replica Buttercup (and sells plans fo it too).

Earl said Buttercup lands in the low 40s with the flaps down.
Or over 70 (with a lot of skipping and skating) without them.

I did a little browsing at the NACA server and found a lot of info on
leading edge flaps. But it all seemed more applicable to supersonic and
high subsonic heavies.

To date, Buttercup is the only light plane I know of that has leading
edge flaps.

Richard


Peter Dohm wrote:

Brock wrote:

I feel there is a real advantage to the use of slats and flaps in
order to have things happen slowly during landing and yet still have a
good cruise speed. Of course the problem is in the complexity and the
extra weight. For rails I was thinking about something like standard
kitchen drawer rails or perhaps a tube within a tube design. I
wouldn't think their would be a lot of force on the slat at low
takeoff speeds so the structure wouldn't have to be bullet proof,
their would probably be a lot more force on the flaps though. I
haven't been able to find information if the necessary airplane
hardware is available commercially, perhaps it would have to be custom
made. Any ideas on how to go about building something like this?

Brock

Whereas the Helio Courier and Morane Rallye (among others), and their
slats, are discussed elsewhere in the thread; I'll just mention that all
of the high wing Cessna aircraft with which I am familiar have single
slotted Fowler flaps. I have no idea how much performance you would
gain with double slotted Fowler flaps, and doubt that they would add
much weight; but believe that they would be a real pain in the neck to
build s the dimensions would need to be held closely in order for the
slots to have the correct proportions and the additional surfaces would
need to be finished.

Peter

The F4-E's originally blown leading edge flaps (drooping leading edge),
in early to mid 1970's they were refitted with leading edge slats. Which
were controlled by a black box and interconnected so you didn't have one
out and one in, like the DC-10 that crashed in Chicago did.
Bill Higdon
Big John wrote:
Richard

Bird landed with some power on engine to provide bleed air to wing. We
had some check outs that flared and pulled the throttle to idle while
still in the air and the bird dropped in. Some of these caused damage
to bird.

Go to Google and search for "F-104 blown wing" and see the details.

Big John

On Sat, 26 Jul 2003 20:09:07 GMT, Richard Lamb
wrote:


One of the NACA Research Memorandum covers what could be the F-104
wing design. Check out "The Effects of Leading Edge Flap Upon
the Lift, Drag, and pitching moment of and airplane employing a
thin, Unswept wing".

It doesn't mention "blowing" the wing, tho.

Richard

Big John wrote:

The F-104 had both leading and trailing edge flaps and wing was
'blown'.

Big John
Mach 1+

On Sat, 26 Jul 2003 02:51:21 GMT, Richard Lamb
wrote:


Steve Wittman had leading edge FLAPS (not slats) on his Buttercup.
Buttercup is a predecessor to the Wittman Tailwind.
That was back in the early '50s?

Anyway, the idea is to have a thin wing for high speed cruise and
recontour it into an undercambered thin wing to slow down for landing.

Thin airfoils tend to have low CLmax while recurred thin airfoils
can have amazingly high CLmax.

Taken to an extreme, the "sail" type single surfaced ultralight wings
show a CLmax of over 4(!)

Leading edge flaps are always(?) deployed in conjunction with trailing
edge flaps of some kind. Even if it is a simple split flap.

Otherwise, the CP would move way forward, and the chord line suddenly
goes the wrong way.

Earl Luce built the first replica Buttercup (and sells plans fo it too).

Earl said Buttercup lands in the low 40s with the flaps down.
Or over 70 (with a lot of skipping and skating) without them.

I did a little browsing at the NACA server and found a lot of info on
leading edge flaps. But it all seemed more applicable to supersonic and
high subsonic heavies.

To date, Buttercup is the only light plane I know of that has leading
edge flaps.

Richard


Peter Dohm wrote:

Brock wrote:

I feel there is a real advantage to the use of slats and flaps in
order to have things happen slowly during landing and yet still have a
good cruise speed. Of course the problem is in the complexity and the
extra weight. For rails I was thinking about something like standard
kitchen drawer rails or perhaps a tube within a tube design. I
wouldn't think their would be a lot of force on the slat at low
takeoff speeds so the structure wouldn't have to be bullet proof,
their would probably be a lot more force on the flaps though. I
haven't been able to find information if the necessary airplane
hardware is available commercially, perhaps it would have to be custom
made. Any ideas on how to go about building something like this?

Brock

Whereas the Helio Courier and Morane Rallye (among others), and their
slats, are discussed elsewhere in the thread; I'll just mention that all
of the high wing Cessna aircraft with which I am familiar have single
slotted Fowler flaps. I have no idea how much performance you would
gain with double slotted Fowler flaps, and doubt that they would add
much weight; but believe that they would be a real pain in the neck to
build s the dimensions would need to be held closely in order for the
slots to have the correct proportions and the additional surfaces would
need to be finished.

Peter

"Bill Higdon" wrote ...
The F4-E's originally blown leading edge flaps (drooping leading edge),
in early to mid 1970's they were refitted with leading edge slats. Which
were controlled by a black box and interconnected so you didn't have one
out and one in, like the DC-10 that crashed in Chicago did.

The last F4 that I saw was at a local military airshow four or five years
ago. It had fixed leading edge slats bolted on to the outboard wing panels.
The pilot said it was a Wild Weasel airplane and one of the last F4s left in
the inventory. I'm sure it's been retired by now.

Rich

On 25 Jul 2003 06:51:08 -0700, (Brock) wrote:

I feel there is a real advantage to the use of slats and flaps in

Slats can work great, but they are a double edged sword. They have to
come out together...Not even one a second earlier than the other. The
Germans had a devil of a time with them on their early attempts.

Then those suckers come out, they come out *now* with plenty of force.

As to fowler flaps, I'm going to have them on the G-III. The factory
makes a kit to replace the standard flaps and they do shave a few
knots off the landing speed.

order to have things happen slowly during landing and yet still have a
good cruise speed. Of course the problem is in the complexity and the
extra weight. For rails I was thinking about something like standard
kitchen drawer rails or perhaps a tube within a tube design. I
wouldn't think their would be a lot of force on the slat at low

When they hit the end of their travel they are really moving. They
"snap" out. Going back in is no biggie from the force standpoint, but
like extension they have to go back in together.

takeoff speeds so the structure wouldn't have to be bullet proof,
their would probably be a lot more force on the flaps though. I

Typically the only ones I've seen were on a curved track and
counterbalanced. If there is an F-84 in your neighborhood, see if
they will let you take a look at how the slats work.

It's one of those simple concepts that works great and can be
difficult to implement.

Roger Halstead (K8RI EN73 & ARRL Life Member)
www.rogerhalstead.com
N833R World's oldest Debonair? (S# CD-2)

haven't been able to find information if the necessary airplane
hardware is available commercially, perhaps it would have to be custom
made. Any ideas on how to go about building something like this?

Brock

Big John wrote:

Only some series of the F-86 had slats. They found in Korea a problem
with them (may have not come out together and threw aim off or
something when pulling 'G's'). They changed in the "F" model to a
solid wing without any slats.

As I always like to point out when aero-deployed slats come
up in the newsgroup, A-4's had 'em too. The Blue Angels
wired 'em retracted to prevent 'bobbles' when maneuvering
in close formation. Aggressors, IIRC, wired them up too.
SOP for most any flight was a slat ops check before maneuvering.
I've written here before about asymmetric slat departures, and know
at least on person who jumped out of an otherwise perfectly good
jet after having one stick in and cause a departure at the top
of a loop. I didn't know they got rid of them on the F-86,
that's interesting.

I'm not a big fan of them and have fought to keep them out of
designs where I've had input. I still can't see a reason for
not having an interconnect that outweighs safety of flight.

Dave 'thunk *crack*' Hyde