Vought F4U Corsair designs and prototypes

[Stargazer]

An F4U was tested with contra props as well.

You're kidding! I've never seen this before! (or maybe I'm getting old?).
I would LOVE to see pics of this, really...

 

[Antonio]

I would LOVE to see pics of this, really...

Here's the beast

Source: Les Avions Vought by Bernard Millot. Docavia Editions Lariviere.


It was an XF4U-4 that received the contrarotating props from Aero Products in June 1945. The evaluation show no increase in performance over the 4-bladed single prop so the later was prefered.

 

[airman]

I would LOVE to see pics of this, really...

Here's the beast

Source: Les Avions Vought by Bernard Millot. Docavia Editions Lariviere.


It was an XF4U-4 that received the contrarotating props from Aero Products in June 1945. The evaluation show no increase in performance over the 4-bladed single prop so the later was prefered.

good, good !

 

[elmayerle]

I caqn see why, if the contra-props offered no performance increase, they stayed with a single four-bladed prop. Going with a single prop would allow a more robust gearbox and at the same time reduce the number of components with potential to fail. That sounds like a win-win to me.

 

[AeroFranz]

The only advantage I would see would be improved carrier landing characteristics (less torque with power application).

 

[Bill S]

F4U-4 with vee tail.
Yes, the drawing says VEE TAIL

I debated which area to put this post in, as I did not find a topic
for the Corsair other than a request concerning the two seater.
Since the drawing is dated 10-3-45 I put it here. Mods can move
if need be.

Enjoy something a little different.

bill

 

[Steve Pace]

Way cool! Do you know what it's V-number is?

 

[Bill S]

Way cool! Do you know what it's V-number is?

No V number on the drawing.
It is referred to as F4U-4 with vee tail

 

[Steve Pace]

Probably V-166 something... V-166B was the XF4U-1.

 

[frank]

I can't believe this could have been seriusly considered, due to the high torque involved during take-off, especially taking into account that the vertical fin had 2 degrees, IIRC, offset built in & also considering the amount of additional rudder that's applied during take-off to counter-act it. Now, if this was shown with the -4 that also tested the c/r prop, I'd feel a bit different..........

 

[saturncanuck]

I would LOVE to see pics of this, really...

Here's the beast

Source: Les Avions Vought by Bernard Millot. Docavia Editions Lariviere.


It was an XF4U-4 that received the contrarotating props from Aero Products in June 1945. The evaluation show no increase in performance over the 4-bladed single prop so the later was prefered.

Wow, what a beast!

 

[Antonio]

Probably V-166 something... V-166B was the XF4U-1.

...or probably something totally different

Some Corsair design numbers:

VS-317 Modifications on XF4U-1
VS-321 Modifications on F4U-1
VS-323 F4U-1 with Wright R-3350 engine
VS-324 Modifications on F4U-1
VS-325 Modifications on F4U-1
VS-331 XF4U-3
V-334 F4U-4 (possible, not sure)
V-336 F4U-1WM (F4U-1 with P&W R-4360 Wasp Major)
V-342 F4U with E engine
V-351 F4U-5
V-354 F4U two seat advanced trainer
V-361 F4U-5 variant
V-376 F4U for Perú

Source: Les Avions Vought. Bernat Millot. Docavia #20

 

[Bill S]

Probably V-166 something... V-166B was the XF4U-1.

Some of the items I have found were just designer general arrangements
and do not look like they progressed far enough to get V or VS numbers.
as their are no detail drawings of parts or further detail.

 

[airman]

from "The Corsair and other Aeroplanes Vought " -
Aviation Heritage Books -1977

 

[Bill S]

XF4U-3

XF4U-3 with a R-2800-16 engine, exhaust driven turbo supercharger and four bladed propeller.
These drawings show inboard profile, induction system and exhaust system.


VAHF archives.


bill

 

[Bill S]

Still have not found a V number for this, pretty sure that it did not
progress far enough to become a fully funded project. I did see
reference in Hosper's notes that the Navy was asking for a VEE tail
to be looked at for the F4U.


bill

Way cool! Do you know what it's V-number is?

No V number on the drawing.
It is referred to as F4U-4 with vee tail

 

[Steve Pace]

Gotta love this! - SP

 

[GTX]

Re: XF4U-3

XF4U-3 with a R-2800-16 engine, exhaust driven turbo supercharger and four bladed propeller.
These drawings show inboard profile, induction system and exhaust system.

More

 

[KJ_Lesnick]

Pometablava

I'm surprised the contrarotating prop did nothing useful: I'd have figured by neutralizing the tangential forces from the prop, you'd add some extra thrust. Still, I suppose the particulars of the propellers and the weight of the new gearing system would play a role too


Bill S

The F4U with a V-tail might not have been such a bad idea. One of the early problems with the plane had to do with spin recovery: The cause was at least partially due to the gull-wing blanking the elevator authority. These surfaces were out of the path of the airflow off the gull wing and would have worked well.

Admittedly the F4U had other problems however owing to asymmetric stalls (occurred at low speed with little warning; fixed with a stall strip), stalls that presented with little warning. and a proclivity to bounce badly on landing

 

[CostasTT]

For carrier duty, the stall characteristics, U/C bounce and prop torque, especially during the takeoff and wave-off phases were serious shortcomings. The first two were eventually fixed, but the last one was never satisfactorily addressed. A contraprop would have solved it, but then again other considerations led to a decision against its adoption.

 

[toura]

Hi all

From the Docavia book "les avions Vought"

F4U-4XB with tanks at the end of the wings

 

[Cy-27]

The F4U-4XB with wing tip tanks photo appears along with the XF4U-4 counter-rotating photo from an earlier post in Barrett Tillman's "Corsair - The F4U in World War II and Korea" (PSL 1979) ISBN 0850594278. This book is probably easier to obtain secondhand than the than the "Les Avions Vought" Docavia title.

Other variants illustrated include the pressurised Vought-Sikorsky Model VS-326, the Goodyear XF2G-1 interceptor and the two-seat F4U-1 trainer.

 

[KJ_Lesnick]

CostasTT

For carrier duty, the stall characteristics, U/C bounce and prop torque, especially during the takeoff and wave-off phases were serious shortcomings.

While I understand why the torque issue was so serious -- it had a huge prop to maximize thrust; to some degree I understand the asymmetry in stall.

I am curious as to how they were able to reduce the spin characteristics and why the undercarriage bounced the aircraft so much on landing? The landing gears didn't look all that unusual (and if anything I'd have though the F6F would have made more trouble).

 

[CostasTT]

https://en.wikipedia.org/wiki/F4U_Corsair#Technical_problems

 

[Jemiba]

In "Wings Of The Navy" by Eric Brown, he mentions the bouncing problems as a result
of overly stiff oleos, but the more serious handicap was the often occuring torque stall
during landing.

 

[Stargazer]

the more serious handicap was the often occuring torque stall during landing.

It can't have happened too often. I guess if it had been such a repeated issue a redesign of the tail might have fixed that.

 

[CostasTT]

Although the stall strip fixed the assymetric stall on wave-off problem, there was still the massive torque of the prop, which could still cause problems in case power was applied suddenly, and that's why Corsairs are seen landing with right rudder applied.

 

[famvburg]

Most, if not all high-powered propeller airplanes have that torque problem. Even a T-6/SNJ with only 600 HP will bite you if power is applied too abruptly at low airspeed.

 

[KJ_Lesnick]

Jemiba

In "Wings Of The Navy" by Eric Brown, he mentions the bouncing problems as a resultof overly stiff oleos

Thank you.


BTW: If I may ask, why were the oleo's designed so stiffly? It may sound like a silly question but other fighters such as the F5F (designed for the same mission actually as the F4U except with twi engines) and the F6F were all carrier based contemporaries (give or take a few years) and they didn't have any problems far as I know.






famvburg


I have a feeling that the issue wasn't so much the torque problem but it's degree. The F4U had a huge prop and powerful engines which would have made things worse

 

[Jemiba]

...why were the oleo's designed so stiffly?

Sorry, there's no reason given for the why . Not a silly question, but one, that may be difficult to answer.
I would expect it to be similar to other problems : A new landing gear needed a new oleo and although not
a new technologyy at all, there was a relatively small kink, that together with other characteristics, like
position of the main gear legs and so on, led to it being prone to bouncing.
Or perhaps the oleos were precisely produced as ordered, but the speciications were wrong ? Things like that
still today result in endless in accusations between companies....

 

[famvburg]

Yes, the Corsair had a huge prop and powerful engine. So did the Hellcat and so did the Bearcat. IIRC, the Hellcat used the same basic prop and did use the same basic engine as well. Regarding the Corsair's struts, the "fix" for the Corsair was to deflate the oleos. That is why the majority of pics show them flat. The majority of plastic models are wrong. The oleos are serviced to enough pressure to assure strut extension after takeoff. That's how the "built-in bounce" was cured. As a sidenote, the Skyraider uses the same main gear as the Corsair.

 

[AeroFranz]

Good account of Hellcat and Corsair pros and cons in Corky Meyer's Flight Journal. at one point both aircraft were evaluated in order to cross-pollinate and improve both. i'll have to dig that out and write a summary.

 

[famvburg]

ISTR the Hellcat was a very docile airplane, a low-experience pilot could fly it with little problem.

 

[KJ_Lesnick]

Jemiba

Sorry, there's no reason given for the why .

Worth a shot...

Not a silly question, but one, that may be difficult to answer.

Yeah, I don't know where I'd go to ask

I would expect it to be similar to other problems : A new landing gear needed a new oleo and although not
a new technologyy at all, there was a relatively small kink, that together with other characteristics, like
position of the main gear legs and so on, led to it being prone to bouncing.

Entirely possible, and now that I think about it, as the plane was designed some changes might have been made -- probably loads of them

Or perhaps the oleos were precisely produced as ordered, but the speciications were wrong ?

Or they miscalculated a variable




BTW: Would one of the warbirds forums have a possible answer? They tend to know all sorts of obscure things about aircraft.

 

[Kartek]

Don't know much about the Corsair but since it was to go to the USMC and thier land bases perhaps the stiff suspension was to help deal with field landings.

 

[AeroFranz]

I apologise for not having looked up the answer yet, my copy of Corky Meyer's book is stashed in a box somewhere. My recollection was that Grumman was given a Corsair to try to emulate the excellent aileron response of the Corsair and Vought was given a Hellcat to improve upon the stall and bounce characteristics of the F4U. IIRC, the former was solved by the installation of a stall strip (a paliative, really), and the latter was cured by varying the characteristics of the oleos.

 

[Bill Walker]

Bouncing is a combination of the rebound of the oleo and the effect this has on the flying surfaces. Geometry of the gear determines how the plane bounces: level, or with the nose dropping or with the nose rising during the bounce. Tail wheel aircraft have the main gear ahead of the c.g., so a bounce usually raises the nose. Nose rising can increase lift, just when you are trying to come down. It also will increase drag, which eventually bleeds off speed and decreases lift, after you are 10 feet back in the air. Usually the first bounce is a nuisance, the second or third bounce may kill you.

Most high powered prop airplanes can get into a dead zone after the first bounce. You are 10 feet off the ground, and airspeed has bled off, reducing the effectiveness of the controls. Now rapidly open the throttle (because you realize you are dropping rapidly) and you may not be able to counter the torque and p-stream effects. The result, at best, can be an uncontrolled descent with high bank angle and/or yaw angle. At worst, it could be a power on stall at low very altitude, resulting in a rapid 180 degrees of roll, high rate of sink, and a very unpleasant encounter with the ground.

The proper response to a bounce seems a little counter-intuitive, and takes some training and a steady head. After the first bounce you abandon the landing. Slowly open the throttle, and apply some forward stick to keep the fuselage level and allow speed to build up. When you can determine that the elevator, rudder and ailerons are effective, gradually add more power. Fly away, go around, and try again.

 

[Stargazer]

I apologise for not having looked up the answer yet, my copy of Corky Meyer's book is stashed in a box somewhere. My recollection was that Grumman was given a Corsair to try to emulate the excellent aileron response of the Corsair and Vought was given a Hellcat to improve upon the stall and bounce characteristics of the F4U. IIRC, the former was solved by the installation of a stall strip (a paliative, really), and the latter was cured by varying the characteristics of the oleos.

Fascinating the things that companies are asked to do in times of war... trying to improve the competition's aircraft!

 

[AeroFranz]

Ok, I dug out the Flight Journal.


The evaluations took place between 9 Sept and 8 Nov. 1943. The Navy wanted Grumman to improve the Hellcat's speed by 20kts (supposedly to cure the Hellcat's inferior speed compared to the F4U) and improve aileron controls. Vought was ordered to improve cockpit layout, visibility, stall characteristics and landing gear oleos.


Vought extended the tail-wheel oleo strut by seven inches to improve taxi visibility. The Hellcat copied ailerons made to the same contour as the Corsair, but wasn't able to duplicate its rolling performance until the introduction of NACA spring tab ailerons.
Turns out in formation flights, the Corsair would read 18 mph faster - so the perceived difference in performance was actually just a sensor calibration issue.


The Corsair's new landing gear strut was modified by Grumman who made it comparable to the Hellcat's. As far as I know, F4U stalls remained nastier than the Hellcat's.

 

[CostasTT]

I apologise for not having looked up the answer yet, my copy of Corky Meyer's book is stashed in a box somewhere. My recollection was that Grumman was given a Corsair to try to emulate the excellent aileron response of the Corsair and Vought was given a Hellcat to improve upon the stall and bounce characteristics of the F4U. IIRC, the former was solved by the installation of a stall strip (a paliative, really), and the latter was cured by varying the characteristics of the oleos.

Fascinating the things that companies are asked to do in times of war... trying to improve the competition's aircraft!

Even more, they would give up their secrets to their peacetime competitors, like Boeing did with the B-29 production pool.