F4U inverted gull wings

I recently visited the Udvar-Hazy facility and received the usual
story about how the Corsair got its inverted gull wings, i.e. to
accomodate the 13 ft. prop which, in turn, was necesitated by the
engines power. However, the Hellcat used essentially the same engine,
and IIRC also used a 13 ft. prop. Yet it did not need those wings.
In fact it was mid winged, not low winged. So what is the true story?
Were the gull wings just one solution. How did the Hellcat
accomodate the prop? Longer landing gear? Or am I wrong? Was the
Hellcat prop 13 ft.?
--

From: (Bob M.)

wroteThe Hellcat) was mid winged, not low winged.

The Hellcat was actually low wing.
Otherwise good historical question.
VL

"Bob M." wrote in message
...

I recently visited the Udvar-Hazy facility and received the usual
story about how the Corsair got its inverted gull wings, i.e. to
accomodate the 13 ft. prop which, in turn, was necesitated by the
engines power. However, the Hellcat used essentially the same engine,
and IIRC also used a 13 ft. prop. Yet it did not need those wings.
In fact it was mid winged, not low winged. So what is the true story?
Were the gull wings just one solution. How did the Hellcat
accomodate the prop? Longer landing gear? Or am I wrong? Was the
Hellcat prop 13 ft.?


Propeller diameter on the F6F-5 was 13' 1".
--

On Wed, 30 Jun 2004 15:38:25 +0000 (UTC), (Bob M.)
wrote:

I recently visited the Udvar-Hazy facility and received the usual
story about how the Corsair got its inverted gull wings, i.e. to
accomodate the 13 ft. prop which, in turn, was necesitated by the
engines power. However, the Hellcat used essentially the same engine,
and IIRC also used a 13 ft. prop. Yet it did not need those wings.
In fact it was mid winged, not low winged. So what is the true story?
Were the gull wings just one solution. How did the Hellcat
accomodate the prop? Longer landing gear? Or am I wrong? Was the
Hellcat prop 13 ft.?

First off, the F6F was a low wing aircraft...

Roscoe
--

Air Force Jayhawk wrote:

First off, the F6F was a low wing aircraft...

Okay...

1) Shorter rear fuselage and tail landing gear struts, so the nose points higher
when the plane is parked,

2) engine is set higher, with the air ducting set under the engine rather than
the wings; the fuselage, while the about the same thickness side-to-side, was
thicker top-to-bottom.

Stephen "FPilot" Bierce/IPMS #35922
{Sig Quotes Removed on Request}
--

Bob M. wrote:
I recently visited the Udvar-Hazy facility and received the usual
story about how the Corsair got its inverted gull wings, i.e. to
accomodate the 13 ft. prop which, in turn, was necesitated by the
engines power. However, the Hellcat used essentially the same engine,
and IIRC also used a 13 ft. prop. Yet it did not need those wings.
In fact it was mid winged, not low winged. So what is the true story?
Were the gull wings just one solution. How did the Hellcat
accomodate the prop? Longer landing gear? Or am I wrong? Was the
Hellcat prop 13 ft.?

I'm not sure if it is the answer - but fitting gull wings (whether
inverted or not) means that the wing root joins the fuselage at approx
90 deg - therebye eliminating the need for a large, drag-producing
wing-to-fuselage fillet.

Having said that, the F4F Wildcat had mid-wings without any fillets.

You only need fillets on high or low-winged a/c

Is the Hellcat mid-winged - I can't remember ?

ken

"Ken Duffey" wrote in message
...
I'm not sure if it is the answer - but fitting gull wings (whether
inverted or not) means that the wing root joins the fuselage at approx
90 deg - therebye eliminating the need for a large, drag-producing
wing-to-fuselage fillet.

Having said that, the F4F Wildcat had mid-wings without any fillets.

You only need fillets on high or low-winged a/c

Is the Hellcat mid-winged - I can't remember ?

Take a look at the picture.....looks like a low wing to me.

http://www.warbirdalley.com/f6f.htm

George Z.

--

I'm not sure if it is the answer - but fitting gull wings (whether
inverted or not) means that the wing root joins the fuselage at approx
90 deg - therebye eliminating the need for a large, drag-producing
wing-to-fuselage fillet.

Uhhh no. The fillets were there to DECREASE drag.

You only need fillets on high or low-winged a/c

Fillets are used to smooth out airflow and thus decrease drag. The air
over a wing is moving at a higher velocity than the air over the
fuselage, and when the streams mix you get turbulence and drag. The
fillets work to counteract this interaction and the drag it causes.

In article ,
(Tracy White) writes:

I'm not sure if it is the answer - but fitting gull wings (whether
inverted or not) means that the wing root joins the fuselage at approx
90 deg - therebye eliminating the need for a large, drag-producing
wing-to-fuselage fillet.

Uhhh no. The fillets were there to DECREASE drag.

That's only true up to a point - A wing/fuselage joint that isn't at
right angles produces quite a bit of Interference Drag, as the
differing airflows try to sort themselves out. Filleting can ease
that transition.

You only need fillets on high or low-winged a/c

Fillets are used to smooth out airflow and thus decrease drag. The air
over a wing is moving at a higher velocity than the air over the
fuselage, and when the streams mix you get turbulence and drag. The
fillets work to counteract this interaction and the drag it causes.

True as far as it goes, but fillets also add wetted area, and increase
Parasite Drag. They're only drag reduction tools when they are
required, and only if used in moderation. It's all a balancing act,
after all - the designer is balancing out the drag increase casued by
the fillet itself, vs. the reduction in interference drag. The
decision made with the Corsair was to reduce the Interference Drag by
acheiving, as much as possible, a wing-fuselage joint perpendicular to
the fuselage, (The inverted gull wing) with a minimum of filleting,
thus reducing Parasite Drag.

--
Pete Stickney
A strong conviction that something must be done is the parent of many
bad measures. -- Daniel Webster

The
decision made with the Corsair was to reduce the Interference Drag by
acheiving, as much as possible, a wing-fuselage joint perpendicular to
the fuselage, (The inverted gull wing) with a minimum of filleting,
thus reducing Parasite Drag.

Actually, the major driver for the inverted gull was finding a way to make
clearance for the HUGE prop so runways and carrier decks didn't get chopped up.
All the drag reduction trades and benefits were a natural fall out of the
design.

Keep in mind, the wings could have been put have been put at the 90 and 270
position and achieved the same benefit. But the prop would have went chop,
chop. Also, the inverted gull was not the best actor in stability and control.
I am not saying that ultimately it was not good, but even then the spins and
the recoveries were an occurence to behold.