F4U inverted gull wings

"DJFawcett26" wrote in message
...

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.


The F6F had the same engine and similar propeller but didn't go chop chop
without the inverted gull wing.

In article ,
(DJFawcett26) writes:
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.

Sorry, but the evidence points in the other direction. There was
nothing particularly outstanfing wrt teh Corsair's propeller diamter -
13'1" for the 3-blade prop, and 13'2" for teh 4-blade - the F6F
Hellcat - no inverted gull wing - low mid-wing, in fact, had no
problems operating in the same environment. - in fact, around the
boat, it was a much better airplane than the Corsair.

The Vought TBU Seawolf, intended to be the successor of the TBF/TBM
Torpedo Bomber, had a mid-wing, and a 13'3" diameter prop.
The low-winged Martin AM-1 attack airplane had a 14'8" diameter
propeller.

The mid-wing P-47 had a 13'2" prop. (And in fact, was flown off of,
but not landed on, carriers in the Pacific, during several of teh
Island-hopping invasions.)

The low-wing Hawker Typhoon & Tempest had a 14' diameter propeller.

The fact is, given the expected speed range of the airplanes, and the
propeller RPM (_Not_ Engine RPM - these are geared engines, all with
a of between 1200 - 1500, a 13' propeller diameter gives the best
advance ratio range for efficiency.

As demonstrated by the small selection of examples above, it was
certainly possible to design an airplane to fit the Corsair's
requirements without resorting to in inverted gull wing to make it
work.

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.

And in fact, it was, on larger aircraft (The TBU, which, interestingly
emough, was the Vought project that followed the Corsair), without any
problems. Stbility wasn't a problem for the Corsair - the objective
numbers Cnalpa, Cnbeta - the Stability deriviatices show that it was
in the middle range for contemprary fighters. Teh stall behavior was
worse than that of the Wildcat & Hellcat, but better than the SBD
Dauntless, the Fw 190, or the P-51. Much of the of Corsair's Torque
Roll tencency at low speeds was corrected by a cuff on the leading
edge of the inboard right wing.

I am not saying that ultimately it was not good, but even then the spins and
the recoveries were an occurence to behold.

From contemporary reports, and objectively obtained data by the NACA,
not any more so than otehr WW 2 fighters, and much less than some.
(You do _not_ want to spin a P-51 with a full fuselage tank, for
example, or a Spitfire with the drop tank in place.)

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

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.?

Corsair propeller diameter 13 feet 4 inches, ground clearance
9.1 inches, engine R-2800-8.

Hellcat propeller diameter 13 feet 1 inch, ground clearance
7.3 inches, engine R-2800-10.

The gull wing was one solution to the trade offs between wing
placement relative to the fuselage, propeller diameter and landing
gear size.

I would suggest looking at cut away drawings to see the differences
between the two types. The Corsair went for a smaller fuselage
size, putting the fuel in front of the cockpit and putting the air intakes
in the wing roots. The Hellcat had the fuel located effectively under
the cockpit, with the bonus that the deeper fuselage raised the cockpit
giving better forward view, very useful for carrier operations, it also had
the air intakes mounted under the engine, hence a larger frontal area
than the Corsair with the inevitable performance penalties but mounting
the engine higher in the fuselage to help propeller clearance. It looks
like the Hellcat's wing was slightly broader than the Cosairs, so more
room for the landing gear and the Hellcat had a smaller landing gear
tread 11 feet versus 12 feet 1 inch so the gear was mounted closer
to the fuselage where the wing was broadest.

Geoffrey Sinclair
Remove the nb for email.

--

In article ,
"Geoffrey Sinclair" wrote:

Corsair propeller diameter 13 feet 4 inches, ground clearance
9.1 inches, engine R-2800-8.



The corsair used a 3-blade prop. Why didn't they use a smaller 4-blade
prop if ground clearance was such an issue?
--

In article , hobo
wrote:

The corsair used a 3-blade prop. Why didn't they use a smaller 4-blade
prop if ground clearance was such an issue?

They wanted to keep the main landing gear as short as possible, to
simplify structural loads. The Hellcat had a relatively long main gear
leg.
--

From: Orval Fairbairn
Date: 7/2/2004 10:30 AM Central Daylight Time
Message-id:

In article , hobo
wrote:

The corsair used a 3-blade prop. Why didn't they use a smaller 4-blade
prop if ground clearance was such an issue?

They wanted to keep the main landing gear as short as possible, to
simplify structural loads. The Hellcat had a relatively long main gear
leg.
--

Corsair had a 4 bladed prop. A 3 bladed prop may have been big enough to
irritate the Seabees who had no sense of humour when it came to prop blades
chewing up their runways.

Dan, U.S. Air Force, retired

"B2431" wrote in message
...

Corsair had a 4 bladed prop.


It also had a 3 bladed prop. It all depends on the specific model.

In article ,
(B2431) wrote:



Corsair had a 4 bladed prop. A 3 bladed prop may have been big enough to
irritate the Seabees who had no sense of humour when it came to prop blades
chewing up their runways.


The early Corsairs used a 3-blade prop, later versions had a 4-blade
prop.

--
Dale L. Falk

There is nothing - absolutely nothing - half so much worth doing
as simply messing around with airplanes.

http://home.gci.net/~sncdfalk/flying.html

In article ,
(B2431) wrote:

Corsair had a 4 bladed prop. A 3 bladed prop may have been big enough to
irritate the Seabees who had no sense of humour when it came to prop blades
chewing up their runways.

The F4U had a three-blade prop from the XF4U-1. The F4U-4 introduced the
four-blade prop on production Corsairs. (The XF4U-3 had a four-blade
prop, but didn't go into production, and the prototypes were returned to
their F4U-1 initial state.)

"Orval Fairbairn" wrote in message
...

The corsair used a 3-blade prop. Why didn't they use a smaller 4-blade
prop if ground clearance was such an issue?

They wanted to keep the main landing gear as short as possible, to
simplify structural loads. The Hellcat had a relatively long main gear
leg.


You appear to be answering a question other than the one asked.
--