F4U vs. F6F

[Saxman]

Farking hell. Was thinking 1 September and typed 1 December.

Anyway, the problem with kills (both total numbers, and by ratio) to decide the "what plane is better" argument is that as has been said, they'll be skewed by an infinate number of factors. I mean, hell, if you go by what the Finns did, that makes the lowly F2A one of the best fighters of the war PERIOD, nevermind that the Buffalo was pretty much proven to be hopelessly outmatched by about any modern aircraft the Japanese could throw at her and most of the Luftwobble birds (I'll probably be corrected on this, but the success of the Brewster there was primarily against similarly obsolete Russian fighters and bombers, correct?).

Also, I noticed there's been a bit of emphasis on turn radius. Isn't overall cornering ability a bit more important than just what plane has the tightest turning circle? There's any number of ways to trim a few yards off a turn, but at least from my understanding not so many ways of boosting the other.

[Brooke]

Turning radius was just the thing that I had some data for, although I could work it around to give turning rate, too.  Even then, it is somewhat artificial, because it assumes all the aircraft are doing 3 g turns.

It is fun to argue the fine points of various WWII aircraft, so that's what folks are doing, even if it is arguing fine points.  My point of view based on what data I had is that the F4U-1D is probably considered the better plane because, while it doesn't turn as well at low speeds, it does roll better and is faster.

On a separate note, I read once that the Finns liked the Brewster also because it was reliable and would run in harsh winter weather.

[hacksaw1]

If you want to go by gutting the cream of the IJN crop, you really have to give props to the F4F. The Battles of Midway and Guadalcanal are what really bloodied the Japanese best fighter pilots, and it was the Wildcat that did it.

Midway - might want to give credit where credit is due: obsolete TBDs of Torpedo 8 drew down IJN top cover in a massacre, but that allowed SBDs to destroy the four IJN carriers, assisted by subs. The IJN pilots perished with the carriers. Not really a claim-to-fame for the Wildcat. But at Guadalcanal it did prove its worth.

Terminology clarification. The Corsair has inverted gull wings. The B-25 has a slight gull wing configuration.

Best regards,

Cement

[F4UDOA]

Brooke,

The 3G stall numbers come from the 1944 JFC. They do not have weight, power or flap condition listed and they are IAS not CAS and the data was collected by about 40 different pilots over a week not in test conditions. The Clmax numbers are calculated from those 3G stall speeds and that is why they are so far off from the NACA report Widewing keeps waving around (I have had it for about 5 years).

The two charts I posted show you exactly what the flight envelopes ofthe aircraft are without power at 12,000lbs not flap. The charts are from the Navy and they came from the pilots manuals of both aircraft.

Most of the information I posted on my website came from Mr.Dean. He was a great guy and thought nothing of lending me a great deal of original information and having me in his house poking around his library. But he wrote a book and it has some errors. I can't help that, I am just posting some of the authentic documentation.

The manuals I get are from

http://www.esscoaircraft.com/

[Saxman]

As a point of order, many of the Japanese pilots trapped on their carriers when they were hit just abandoned ships to be picked up by the escort ships.

[SkyRock]

Hogs RULE!:D

[Widewing]

Originally posted by F4UDOA
Widewing,

I agree with NACA. Did you actually read the document you referenced? As for my F4U lovefest you might notice the name of this thread is F4U Vrs F6F. The next P-38 lovefest you can do the fawning.

My information comes from when I was standing in Mr.Dean's study a few years ago before he passed and I asked him where he got those Clmax numbers. He got (at least some of them if not all of them) from the 1944 Joint Fighter Conferance test results of 3G stalls. Most of them make no sense what so ever when compared with real life Clmax numbers.

The only one that is accurate is the F4U at 1.48 which may have come from the NACA report burried somewhere but I doubt as it only makes reference to the F4U Clmax of 1.88 with full flaps or 1.17 or 1.26 on page 25 with no flap and no propellor. I know you didn't read the thing or you would have seen that.

America's Hundred Thousand list the F6F-5 Clmax as 2.27. NACA shows it on page 25 with no flap and no propellor as 1.40 approx and approx 1.9 with prop idling.

So no NACA is not wrong but it also has nothing to do with the Clamx numbers in AHT.

What is the Clmax of the F4U and F6F? That is easy on most A/C such as the F4U, P-51 etc. Except the pitot tube error is so bad on the F6F that the CAS chart still makes it subjective. The IAS stall is roughly 73Knots and the pitot error says add 4Knots so that puts the stall at roughly 90MPH at 12,000lbs.

Both from the Pilots Handbooks

12,000 * 391 / 90^2 * 334
4692000 / 2705400
Clmax = 1.73 Which I have to say is higher than I thought it would be.

The F4U-1

11,300lbs * 391 / 97^2 * 314
4418300 / 2954426
1.49 On the money

Now recalculate AHT performance index with the right Clmax. Also take a look at the 1944 JFC and notcie the Mr.Dean is the publisher of the minutes through Shiffer Books.

Now look at the real EM diagram for the F6F and F4U. Which one has the better turning ability?

Ah... Operational Strength Limits charts are not Energy Maneuverability Diagrams.... That should be obvious. Moreover, notice the backside of the curves. The maximum speed @ 7g below 10k for the F4U is 340 knots. However, the F6F-5 is allowed 370 knots when loaded to 7g at the same height. This difference prevails over the entire speed and altitude ranges of the charts. Why is this? Apparently, the F6F is allowed much higher speeds over the g loading range at all altitudes. Now, look to the far right side of the chart. Notice that the F6F-5 is allowed 480 knots @ 3 g, but the F4U is restricted to 410 knots when loaded to 3 g..

I'm not an aeronautical engineer, I'm a mechanical engineer. That said, it seems to me that the F6F-5 has a considerably stronger airframe (or at least rated that way by the Navy) than the F4U, at least the way I'm reading these charts.

Back to NACA 829.... I only had time to read a portion of it. However, it appears that the CLmax for both aircraft drops dramatically if an actual service aircraft is tested, more so for the F4U. I suspect that recalculating turn index should be based upon the far lower CLmax of service aircraft, not those aircraft specifically prepared to test the "perfect" airplane.



I suspect that "real world" turn performance will be more accurately modeled on service aircraft.

My regards,

Widewing

[parin]

Hellcat:aok

[Widewing]

Originally posted by Widewing
Notice that the F6F-5 is allowed 480 knots @ 3 g, but the F4U is restricted to 410 knots when loaded to 3 g.

Actually, the F6F-5 is permitted 440 knots, not 480 knots. I plotted the F4U onto the F6F graph so you can better see the differences at various g loadings/speeds below 10,000 feet.



Can any of our aeronautical whizz-kids tell me why the F6F is permitted substantially higher speeds relative to g loading?

My regards,

Widewing

[F4UDOA]

So do you concede that Dean's Clmax's are all off?

The NACA data and Dean's data don't match at all.

Also the charts I posted from the manuals are in IAS not CAS.

At 300Knots IAS the F4U requires you to add 8 knots.

At 300Knots IAS the F6F-5 with the later pitot tube configration requires that you subtract 2.5 knots.

Also the bounder layers established at lower speeds are stall limitations of the airframe, not limitations for tearing your wings off. The Grumman will not loose his wings if he exceeds 3G's at 150knots but he will enter the buffet boundery and begin to stall. That is obvious.

This fact can be supported by the SETP (Socioty of Experamental Test) when they tested the two aircraft in both 3G stall, high speed stalls and max performance 180 degree turns.

The Grumman was well underweight at 10,681LBS and the F4U was at 11,055lbs putting the Grumman well underweight by 500+lbs compared to the F4U. The P-51D weighed 8,900LBS and the P-47D40 weighed 11,535lbs.

Test 1
3G stalls at power degrading airspeed less than 1 knot per second.
F6F-5= 95Knots
F4U-1D= 98 Knots
P-47D-40= 109Knots
P-51D= 122knots

Test 2
Max G turns from V-Max at 10,000FT
F6F-5 reached light buffet at 6G while at lowest top speed of any aircraft tested.
P-47 reached light buffet at 4.8G and moderate buffet at 5.2G
P-51 and F4U had no buffet up to 6G max tested.

Test 3
Level 180 degree turn around at METO power (normal) 220Knots 10,000FT

P-51D= 10 seconds
F6F-5= 9.9 Seconds <== Worse than the P-47!!
P-47D= 9.7 Seconds
F4U= 8.5 seconds

None of these results show the F6F to be a super plane in the turning regime even when at a significantly reduced weight compared to it's competitors.

[Brooke]

There is really only one way to settle all of this.  It is for someone to buy me one F6F-5 and one F4U-1D.  I will then test them both.  I'll let F4UDOA and Widewing fly them, too.

[Widewing]

Originally posted by F4UDOA
So do you concede that Dean's Clmax's are all off?

The NACA data and Dean's data don't match at all.

Also the charts I posted from the manuals are in IAS not CAS.

At 300Knots IAS the F4U requires you to add 8 knots.

At 300Knots IAS the F6F-5 with the later pitot tube configration requires that you subtract 2.5 knots.

Also the bounder layers established at lower speeds are stall limitations of the airframe, not limitations for tearing your wings off. The Grumman will not loose his wings if he exceeds 3G's at 150knots but he will enter the buffet boundery and begin to stall. That is obvious.

This fact can be supported by the SETP (Socioty of Experamental Test) when they tested the two aircraft in both 3G stall, high speed stalls and max performance 180 degree turns.

The Grumman was well underweight at 10,681LBS and the F4U was at 11,055lbs putting the Grumman well underweight by 500+lbs compared to the F4U. The P-51D weighed 8,900LBS and the P-47D40 weighed 11,535lbs.

Test 1
3G stalls at power degrading airspeed less than 1 knot per second.
F6F-5= 95Knots
F4U-1D= 98 Knots
P-47D-40= 109Knots
P-51D= 122knots

Test 2
Max G turns from V-Max at 10,000FT
F6F-5 reached light buffet at 6G while at lowest top speed of any aircraft tested.
P-47 reached light buffet at 4.8G and moderate buffet at 5.2G
P-51 and F4U had no buffet up to 6G max tested.

Test 3
Level 180 degree turn around at METO power (normal) 220Knots 10,000FT

P-51D= 10 seconds
F6F-5= 9.9 Seconds <== Worse than the P-47!!
P-47D= 9.7 Seconds
F4U= 8.5 seconds

None of these results show the F6F to be a super plane in the turning regime even when at a significantly reduced weight compared to it's competitors.

How about recalulating for NACA's 1.17 CLmax for the service F4U? Which, by the way, is a heck of a lot lower than Dean's or yours.

I'm also aware that the front side of the curve is not about structural limits, but the back side most certainly is. The back side says that the F4U was rated for lower speeds than the F6F for any given G loading on the airframe.

As to the SoETP symposium, I read their book several years ago, having borrowed it from Grumman test pilot Tom Gwynne. However, I don't have it now, so until I can compare it to what you've posted, I'm gonna view your comments in the same light as I did your previous comment about F4Us scoring better than the F6F in 1943, while evading the context that F6Fs only saw combat during the last 1/3rd of the year. Besides, if the P-47 is turning 180 degrees faster than the F6F and P-51, clearly there's something amiss in the test method or the aircraft or even the piloting. You know as well as I do that personal preferences and preconceived opinion will skew test results, and any test not managed by test engineers is little more than an exercise. Besides, you may be cherry-picking data, sort of a Crumppster in Blue.

You are hanging your hat on a mighty sharp hook. I have never heard any pilot, who flew both the F6F and F4U, state that the F4U was better around the boat, or could out-turn the F6F. Not one. I spent more than a few years in Naval Aviation and have 332 traps to my credit. So, I know a few things about carrier aviation and the men who fly from them. I've chatted with many WWII vets. I've chatted with test pilots, in particular test pilots who worked for Grumman.

Universally, Japanese pilots feared the F6F more than the F4U. They have stated that the F6F could dogfight with them, while also stating that the F4U could not hope to.

The fact remains that the F6F, with not a great deal of help from the F4U, destroyed Japanese Naval aviation. Where the F6F encountered Japanese Army fighters, it was just as dominating. There's no doubt that the Hellcat was the most important fighter of the Pacific war. Anyone arguing otherwise is either misinformed, or being deliberately obtuse.

Does that make the F4U inferior? Not at all. Possessing somewhat different attributes, the F4U was a terrific fighter. Fast, excellent high-speed handling, decent turning and very rugged. But it was not better than the F6F at what both were designed to do; defend the fleet, escort the bombers and control the sky anywhere they flew.

My regards,

Widewing

[Brooke]

Originally posted by Brooke
If you scale things to "index units" so that 139 m is 12.0 index units, the radius for the F4U-1D comes out to 18.5 (not the 25.4 listed in the book).

So, the F4U-1D has a much larger turning radius than the F6F-5, but not as much larger as listed by the "index units" measurement in the book.

Oops.  The book has the F6F at 16.5 "index units" (not 12.0, which is what it listed for the FM-2).  In that case, the F4U-1D by the above (not using CLmax, but just using the 3g stall speeds) does come out to be 25.4.

So, the book's numbers are correct if the 3 g stall speeds are correct, regardless of the CLmax's listed -- but not correct if the 3 g stall speeds are wrong, as pointed out by F4UDOA.

[F4UDOA]

Thank you Brooke,

I am only asking that you consider the source.

Widewing,

It is funny you should Crummp me as you did because I was going to do the same with you.

When some facts fit your needs like the 3G stall speeds of the JFC you stick with it until the death but when I say that 60% to 30% of the pilots at that conferance chose the F4U as the best Navy fighter you say the conferance was a boonedogle and has no value. You wave the NACA report in my face as proof of your point without ever reading the report that confirms my opinion in the first place.

I know you have a long service career and I am also aware from my 4 years of service as an Avionics Tech that on ships and aircraft they like to say things like "God is in the Details". But you are not a detail guy. Detail is noticing IAS vrs CAS and Clmax numbers that are way out of line or bothering to read the report you are waving like a flagCrummp!!. Also you choose selected Japanese pilot annecdotes that are turely worthless to proove a point about detailed aircraft engineering.

No matter what my opinion or your opinion this arguement was settled by the Navy in 1945 when the F4U took over as the primary carrier fighter.

I truely enjoy this discussion because it has some great points of debate. But you have got to recognize that every independant body that has ever accomplished this test has settled in one direction and not the other.

[bozon]

lets not get low with name calling. I like both your postings and I'd hate to see you muted.

I think it is quite a wide spread opinion that from pure performance point of view the F4U had the edge over the F6F. Even if we neat pick the data we get the conclusion that at best, the F6F was equal to the F4U and not better.

In AH the F4U wins the contest hands down. Again, not that the F6F is bad, but the F4U is a little better.

However, the F6F had some advantages over the F4U in areas entirely un-related to fighting performance. Mentioned above were stall behaviour, deck operation, reliability, etc. Also, wasn't the F6F featuring a unique way of wing folding that saved a lot of storage space?

Since some of you are well versed in the navy history, can you please tell when was it decided and why the navy ordered so many more hellcats. Did they prefered it over the F4U because of these "little" things or was Grumann just able to produce and deliver what Vought couldn't? was it cheaper? Or was there some corruption and favoritism, a few bribes maybe... you know, juicy gossip

Bozon