Myth or fact > F8F

[Angus]

8 mph is not much of a difference - just the little odds like the paint and such will create that much of a measured difference.

[Squire]

The N1K1 did have its share of gear and engine problems, the N1K2 of 1945 got rid of most of the landing gear woes, but the tempermental engine still gave it troubles until war's end. I have also read that its engine was not easy to service.

All that being said, when it was up and running properly, the N1K2 was a formidable fighter, and certainly more so than an A6M5.

It really ran out of time before reaching its full potential, like many of its cousins. Its fair to point out its shortcomings, but one has to remember the context as well.

[Widewing]

Originally posted by F4UDOA
Widewing,

Meyer has always maintained the similarity of performance of the F6F and F4U. However the NAVAIR and TAIC don't really show what he describes. In fact all of the Grumman factory climb results are much higher than the tested results which makes me suspicious of Meyers claim about the speed and climb of the XF6F-6.

Do you know of any published results for the bird that do not come from Grumman? I can't find anything that shows faster than 425MPH and most sources say 417MPH.

There's no doubt that Grumman's performance numbers were always better than Navy data. There was several reasons for this.

The Navy always tested at max gross weight, Grumman usually tested with one hour of fuel, plus reserve. Grumman generally did not add ballast for uninstalled ammunition (although Republic did). Grumman primped and preened the aircraft before testing, whereas the Navy flew them as is/was.

My understanding from what Meyer wrote was that 425 mph was WEP without water injection. F6F's had a seperate switch to turn on the water pump, it was not part of the throttle quadrant rigging. I've seen 417 mph in several sources myself. It is possible that this is max speed at MIL power. It's also a possibility that the 417 mph is uncorrected for pitot error. Once Grumman established that pitot error was the biggest factor in the apparent speed differential between the F4U-1A and the F6F-5, they developed a correction scale to determine actual IAS.

I have not seen any test data beyond that generated by Grumman. I do believe that two Navy test pilots did fly the XF6F-6 planes, but did so at Bethpage (factory).

My regards,

Widewing

[Squire]

This has come up before, but what are the Navys #s on the F6F-5?

Is this "F6F-5 too slow" stuff based around either Grummans #s or the F6F-6?

[ShortyDoowap]

Hi, first time poster, long time lurker.  Saw this conversation and it interested me.

About the XF6F-6:  the 425mph speed was achieved at 2,450 hp.  2,450 hp is a wet WEP rating for the R-2800-18W engine.   Any speed achieved in excess of that figure would have been at wet WEP.  Otherwise, it was achieved at a weight far below anything, or a condition cleaner than anything (or both) that would be used in service.  

The commonly published 417 mph speed for the XF6F-6 is unlikely to be a military power speed.  More than likely it is a wet WEP combat speed – ie, with racks and zero-length launchers.  The 425 speed is likely a wet WEP clean speed.

BuAer/NAVAER routinely published speeds for their planes in "Clean" and "Combat" configurations.  "Clean" was sans bomb-racks or zero-length rocket launchers.  "Combat" was with those accessories.    For instance, the F4U-4 "Combat" speed at wet WEP was 393 knots (452 mph).  "Clean" speed was 403 knots (463 mph).  Both on 115/145 grade fuel.  On 100/130 PN fuel, published speeds are around 446 mph combat, 452 clean (iirc).

With respect to the XF6F-6 outperforming the XF4U-4:  I haven't seen any performance figures to suggest the XF4U-4 performed substantially worse than the production plane.  Given the fact that the XF4U-4 had a better drag coefficient than the XF6F-6, had better power loading, similar wing loading, and the same engine, I find it incredibly difficult to believe that the XF6F-6 outperformed the XF4U-4.   I also believe its inferior performance to the F4U-4 was one of the reasons the Navy chose the F4U-4, and one of the major reasons Grumman terminated development of the XF6F-6 even before testing was complete.

BuAer's published INITIAL climb rate for the F4U-4 in combat configuration at 60" hga MAP was 4,400 fpm.  Yet there is a claim in this thread that the XF6F-6 climbed to 15,000 feet in 3.4 minutes.   That’s an AVERAGE climb rate of over 4,400 fpm.   In other words, somehow the XF6F-6, with worse drag coefficient, worse power loading, similar wing loading, and same engine not only out climbed the F4U-4, but did so by a substantial margin.  I don’t dispute the information provided, but details of that test would be appreciated, along with the configuration of the test plane - because something doesn’t add up.

Published performance figures for the XF6F-6 and the F4U-4 at clean, loaded and maximum weights and power ratings speak for themselves.  The F4U-4 was the superior plane – no question about it.  

---


With respect to the claim that the F8F copied the Fw-190 landing gear/spar configuration:  the F8F used the same construction method as the F6F.  The construction was web and cap strip construction, with a fore and aft spar, the fore being larger and stronger.  Both spars extended the entire length of the center wing section.   As with the F6F, the gear was hinged ahead of the main spar, the difference being that the F8F gear retracted towards the center, while the F6F’s gear retracted backwards.  To suggest the Bearcat copied this from the Fw-190 ignores the fact that such construction existed in the F6F.

[ShortyDoowap]

Originally posted by Widewing
There's no doubt that Grumman's performance numbers were always better than Navy data. There was several reasons for this.

The Navy always tested at max gross weight...

Hmmmm, they certainly didn't publish their performance figures that way.

NAVAER "Standard Aircraft Characteristic" data sheets for Navy fighter aircraft listed perfomance in several different configurations such as
fighter-clean, fighter-combat, fighter-extra fuel tank, rocket, escort, etc. Testing only at max gross weight would have left a huge void of knowlwedge as to how an aircraft would perfom under other conditions.

[Crumpp]

Both spars extended the entire length of the center wing section.

The main wing spar on the FW-190 extends throughout 3/4's of the entire wing, not just the center section.

Here is a picture of Black 3's wing.  The main spar runs from outboard the gun bays thru the center.  It is one solid piece and not bolted together.

http://www.white1foundation.org/photos/Black3/21.jpg

The F6F main spar comes in 3 sections and is bolted together in the wing.  With the exception of the portion that folds up to allow storage.

All the best,

Crumpp

[ShortyDoowap]

Originally posted by HoHun
The F8F was a copy of the Fw 190 adapted to a US-built engine, US armament and the requirement for carrier capability.

This seems absurb, and baseless.  There was nothing special about the construction or design of the F8F that can be traced directly to the Fw-190.  Similarities are superficial.  

The F8F was designed in accordance with Roy Grumman's desire to produce a small, lightweight, high performance fighter that could operate from small carriers - small carriers that were becoming ever-more common.  R. Grumman expressed concern to his chief engineer, Bill Schwendler, in July 1943 that Grumman was over-relying on twin engined aircraft in the belief that's what BuAer wanted.   R. Grumman wanted a small plane he could market to BuAer as a "converted carrier fighter."  His specifications were for a plane that:  1) had the same dimensions as the Wildcat, 2) had a gross weight of 8,500 lbs, 3) has a 2 speed R-2800 engine, 4) 170 gallon internal fuel capacity, 5) bubble canopy, 6) wide track undercarriage providing adequate propeller clearance, 7) superior perfomance to the Hellcat, 8) power loading of 4 hp/lb and wing loading of 33 lbs/sq ft.   It took examination of an Fw-190 to come up with that?  Had the Fw-190 truly inspired the Bearcat, the Bearcat would have performed worse than it did.

Just look at the placement of the landing gear in front of the fore spar which leaves the main part of the wing a full-monocoque torsion box, a unique feature of the Fw 190 and the "secret" of its strong wing construction.

Regards,

Henning (HoHun) [/B]

See my last post.  Nothing "unique" about that.  Of course while the Bearcat and Hellcat had folding wings, the center sections were built of two spars extending the entire length of the center section.  Thh gears on both the Hellcat and Bearcat hinged ahead of the main spar.  R. Gumman and company didn't need to examine a Fw-190 to come up with something they already knew.

[ShortyDoowap]

Originally posted by Crumpp
The main wing spar on the FW-190 extends throughout 3/4's of the entire wing, not just the center section.

Crumpp

The Beatcat had folding wings, the Fw didn't. The Fw didn't have a "center section" in the manner the Bearcat did.  It would have been impossible to have folding wings if the spars extended beyond the center section.  

[F4UDOA]

The thing about the F6F-5 is the TAIC and NAVAIR results that always make me question how Grumman conducted their test.

For instance the F6F-5 climb is rated as higher than that of the F4U-1A/D in most sources including here in AH. However this is only if you use Grumman performance numbers. When you look at the TAIC test done in two individual test vrs the FW190 and A6M5 the F4U-1D outclimbs the F6F-3 and then the F6F-5 (by as much as 500FPM). This F6F acheived 409MPH at 22K so it was performimg very well. This results also supported by the NAVAIR test of both A/C which has a 1 minute climb adavantage for the F4U.

In anycase it would surprise me if the XF6F-6 could outclimb the F4U-4 considering the history of their predecessors.

[Crumpp]

The Beatcat had folding wings, the Fw didn't.

Your completely misunderstanding what I posted.  I know the Bearcat has folding wings.  However, it's main wingspar runs almost the same length as the Focke Wulfs:

http://www.shanaberger.com/images/F8F_3.htm

And folds completely differently from the F6F:
 

Notice the difference?

All the best,

Crumpp

[ShortyDoowap]

Comparing climb rates is very difficult.  What appears to be a simple comparison may be an exercise in "apples and oranges."  I've seen varying climb rates for the F6F-3/5 and F4U-1/A/D.  It's important to compare planes in similar configurations.  Are you comparing a clean F6F to a F4U with racks and rails?  Often times, test summaries don't tell you that.   I'm not attempting to answer any question, simply making an observation you probably already understand.  

My interest was specifically the F4U-4 and F6F-6.  Given differences in drag coefficients, weight, power and wing loading, its not hard to guess which plane would perform better even had no tests been available.   If the XF6F-6 outperformed the XF4U-4, then there was something unusual about one of the planes that allowed the Hellcat to overcome the advantages of the Corsair.   Comparing the planes side-by-side in similar configurations, the -4 Corsair outperforms the -6 Hellcat.  Obviously, Grumman and the Navy recognized that, too.

[Crumpp]

Had the Fw-190 truly inspired the Bearcat, the Bearcat would have performed worse than it did.

That's funny....

The FW-190A9 is around 300lbs lighter empty than the F8F-1.  Of course it is not surprising when the FW-190A9 is faster than the F8F-1.

Again, contact the NASM Garber Facility.  They have practical experience with both aircraft and get the word from them.  I did.

All the best,

Crumpp

[ShortyDoowap]

Originally posted by Crumpp
Your completely misunderstanding what I posted.  I know the Bearcat has folding wings.  However, it's main wingspar runs almost the same length as the Focke Wulfs:

http://www.shanaberger.com/images/F8F_3.htm

And folds completely differently from the F6F:
 

Notice the difference?

All the best,

Crumpp

No, I haven't misunderstood what you said.   You may wish to reread my post in the context it was intended, and that was in response to this:

The F8F was a copy of the Fw 190 adapted to a US-built engine, US armament and the requirement for carrier capability.

Just look at the placement of the landing gear in front of the fore spar which leaves the main part of the wing a full-monocoque torsion box, a unique feature of the Fw 190 and the "secret" of its strong wing construction.

"Just look at it?"  OK, I've looked at it.

The Bearcat gear hinges ahead of the main spar.  So did the Hellcat gear, though they retracted differently.  If Grumman had experience hinging a gear ahead of the main spar, why does HoHun attribute that feature to the examination of the Fw-190?   Doesn't make any sense.

And if the spar construction was different than that of the Fw-190, that sort of detracts from the argument that they were similar, and therefore inspired by the Fw-190.

Two different planes, two different designs, with superficial similarities.  

The Bearcat was not a "copy" of the Fw-190.  The arguments presented thusfar to support that theory fail.

[ShortyDoowap]

Originally posted by Crumpp
That's funny....

The FW-190A9 is around 300lbs lighter empty than the F8F-1.  Of course it is not surprising when the FW-190A9 is faster than the F8F-1.

Again, contact the NASM Garber Facility.  They have practical experience with both aircraft and get the word from them.  I did.

All the best,

Crumpp

Garber isn't the official respository for Grumman '40s and 50's era documents, the Grumman Historical Center at Bethpage, New York is.   If you want good Grumman technical drawings of the Bearcat or other documents, contact the the GHC.  It's from there that I received mine.

BTW, planes don't fly at empty weight.   At a loaded 9,200-9,300 lb weight, the F8F-1 had a top speed of 434 mph at 19,800 feet.   It also had a military power (NOT combat power) initial climb rate of 5,000 feet per minute.   How does that compare to the Fw-190A-9?