Slats and Fowler Flaps On Light Plane

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

Brock wrote:
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,

If there isn't a lot of force on them then they aren't doing you any good.


--
----Because I can----
http://www.ernest.isa-geek.org/
------------------------

Ernest Christley wrote:

Brock wrote:
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,

If there isn't a lot of force on them then they aren't doing you any good.

--
----Because I can----
http://www.ernest.isa-geek.org/
------------------------

When the slats pop out on the Helio Courier based here,
it sounds like a shotgun. Loud BOOM!

There is indeed a lot of force here...

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

"Brock" a écrit dans le message news:
...
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

I fear that if flaps has some aerodynamic effect, they HAVE to be bullet
proof.
Just imagine what could happen in cas of disymetrical openning. Or one side
flap locked in landing configuration, the other side retracting. I dont
think aileron whould have enought authority to overcome the roll.

And for fowler flaps, I unterstand it is the ones that go aft before
rotating.

What about ordinary rotating flaps, but with a very low rotation points. Say
rotation point one feet below the wing. at 45° extention, the leading edge
of the flap would be (sin (45°)) aft. No need for rails. A bunch of slotted
flaps on certified planes just act like this.

Other point to consider a
-Tail should have enough authority to compensate the pitching moment.
-your plane should have enough power to have a positive climb rate, at full
load with flaps, fowlers, landing gear fully extented.