F6F Hellcat vs. P-47 Thunderbolt

[drgondog]

P-80...the jet???? That never saw combat in ww2, did it?? I know it flew but i think it was still being developed, for the most part, before the war ended.

Yes and no. It was deployed to Europe for operational testing in Dec 1944 - several months before the P-47N entered combat. The first crash of the p-80 occurred in England that same month, IIRC due to a faulty exhaust system

i think Republic wanted people to know they could still make legendary airplanes, if needed.

The P-80 was fully operational in the US before the war ended. Had the US wished to suffer losses due to teething problems I suppose the P-80 could have been in combat ops before VE Day - but why bother?

 

[davparlr]

My source gives the climb rate of the P47N at combat power as worse than the early P47s which was not good and at military power was barely over 1700 FPM up to 20000 feet.

You kind of have to watch the weights. The chart for the M is flown at a weight of 14700 lbs and the N is 16700 lbs, 2000 lbs more but the N has a basic weigh of only 500 lbs more than the M. It doesn't show the weight on the charts for the earlier P-47 so comparisons are difficult. I suspect that it is a significant difference in test weight even though the basic weight of the N is only 800 lbs more than the D-25.

Other test and company predictions show the N as capable of 3600-3750 ft per min in WEP at a lessor weight, around 14k lbs. Dean shows about 2600 at 16k lbs.

 

[renrich]

Dav, I am pretty sure we are preaching from the same hymnal, Dean. He states that at full load the N was toting about 3000 pounds more than earlier models which made it a slow climber. Of course it was designed as a long range escort fighter so presumerably a lot of that extra weight of fuel would be gone by the time it got into a fight. As you know and have stated, the tricky thing about performance data which we see online or in print is that we often see Vmax, max rate of climb, max range and max combat load quoted as if they all happen at the same time and at the same altitude. Taint true. Those max performance figures usually only happen at the airplane's best altitude, combat power(which can't be sustained for long) and at lighter weights. Of course, I am not telling you anything new. One thing I learned while rereading Dean about the P47 answered a question I have had for a while about why the Corsair did not utilise the paddle blade prop to increase it's rate of climb, like the later Jugs did. That higher activity prop on the P47 caused some lateral stability problems which the Corsair definitely did not need, especially during a wave off. I suspect that is why Vought stayed with the toothpick blades.

 

[davparlr]

Dav, I am pretty sure we are preaching from the same hymnal, Dean.

Dean is a great book. I wish we had such a book on the British and German and others. It would make it much easier to compare.

He states that at full load the N was toting about 3000 pounds more than earlier models which made it a slow climber. Of course it was designed as a long range escort fighter so presumerably a lot of that extra weight of fuel would be gone by the time it got into a fight.

Yes, I have always wanted to standardize some kind of weight comparison, but available data often prohibits it, allowing only analysis, which HoHun seems to be good at.

As you know and have stated, the tricky thing about performance data which we see online or in print is that we often see Vmax, max rate of climb, max range and max combat load quoted as if they all happen at the same time and at the same altitude. Taint true. Those max performance figures usually only happen at the airplane's best altitude, combat power(which can't be sustained for long) and at lighter weights.

All True.

One thing I learned while rereading Dean about the P47 answered a question I have had for a while about why the Corsair did not utilise the paddle blade prop to increase it's rate of climb, like the later Jugs did. That higher activity prop on the P47 caused some lateral stability problems which the Corsair definitely did not need, especially during a wave off. I suspect that is why Vought stayed with the toothpick blades.

Interesting. I hadn't read that.

 

[davebender]

Had the US wished to suffer losses due to teething problems

After the P-38 and B-29 experience I don't think anyone in the U.S. Army Air Corps will recommend this solution.

 

[Magister]

Renrich, I did not know about the paddle prop instability issues with the corsair. I was wondering why the higher thrust prop wasn't employed for the Corsair.

I believe that some of those impressive F4U-1 performance tests on the Spitfire Performance site were with the paddle prop. A non-production experimental prop in any event.

 

[renrich]

Page 302 and 303 in Dean describes some of the issues which were at least partially remedied by the dorsal fin on the P47M. These issues were most revelant at low speeds. I do believe I also read that some of those same issues cropped up with the F2G with the bubble canopy and they also occurred in the early P51Ds with the bubble but were rectified with the dorsal fin. I believe the F4U1 tests referred to were using a prop which was slightly different in diameter but still not the paddle blade but the F4U1 might have been a "cleaned up" version. I saw that test on Mike Williams site and the performance numbers were startling. It would be really fun if a Dean book existed for all British, German and Japanese fighters. Then I could be even more confused than I already am.

 

[Magister]

"Page 302 and 303 in Dean describes some of the issues which were at least partially remedied by the dorsal fin on the P47M."

Didn't the retrofitting of the dorsal fin predate the introduction of the paddle blade? My understanding was that the dorsal fin was installed as a result of instability caused by the loss of keel surface on the bubble canopy variants and that it was that modification that brought about the small dorsal fin.

I have never read anything that even hinted that the paddle blade had a role in the use of the dorsal fin.

I need to get a hold of a copy of that book. It has some great information.

 

[HoHun]

Hi Clay,

>The P-47 killed more planes (I think) than the P-51 but was overshadowed by it. The F6F was similarly overshadowed by the F4U Corsair though it definitely killed far more enemy aircraft

Here some graphs comparing the F6F-5, F4U-1 and the P-47D.

(The P-47D is a "quick" analysis based on the assumption that the engine really produces constant power from sea level to critical altitude, which according to its rating it did, but in practice not quite.)

Clmax for the P-47D is assumed as 1.2, which appears a realistic value in the absene of actual measured data.

Weight, power and top speed data is from the F4U-4 comparison report. It has been suggested that the P-47D in question is a razorback with "small" fuel tank if I remember correctly, so it's a relatively fast and light representative of the P-47D.

I'd take the P-47.

Regards,

Henning (HoHun)

 

[renrich]

Fitting of the paddle blade props(Curtis 836 design in place of the 714) began in December, 1943, one squadron at a time. I believe this predated the bubble cockpit P47. The Dean book is highly recommended if you like airplanes. As I have mentioned before, and this has nothing to do with the Hellcat, my uncle who was an IP on P47s said they were regularly waxed by F4Us in mock dogfights.

 

[Magister]

Don't think those charts are correct.

 

[renrich]

I believe those charts are self generated. I wonder how they can be accurate.

 

[mikamee14]

P-47 bar none

 

[JoeB]

Don't think those charts are correct.

Don't know, but don't see a reason to take them as firm facts. They look nice though.

Joe

 

[davparlr]

Don't think those charts are correct.

Some random checks with my data base, based on mostly flight test data, shows the charts to not be very far off, although there was some optimism on climb for the P-47 but all are probably in the margin of error. I dont have data on turn rate, but the trend shown does not look unreasonable.

 

[Magister]

optimism on climb for the P-47

Optimism? At over 3,500fpm, (the way it looks to me) it looks optimistic indeed.

 

[Demetrious]

optimism on climb for the P-47

Optimism? At over 3,500fpm, (the way it looks to me) it looks optimistic indeed.

I must agree, gentlemen. The late-war Spitfire IX, one of the best climbers of the war bar none, only managed 4,500 fpm. 3,500 fpm for an aircraft that drew cries of "where's the other engine!?" when it was first introduced seems a bit excessive.

That said, an "average" climb rate was all the P-47 needed, with it's excellent performance in most other areas. As long as climb performance was not cripplingly poor, it could prevent better-climbing 109's from dominating the P-47 in the vertical.

 

[davparlr]

optimism on climb for the P-47

Optimism? At over 3,500fpm, (the way it looks to me) it looks optimistic indeed.

AF test run Oct 6, 1944, show SL rate of climb as 3180 ft/min. Max climb on another test, 44-1 fuel, shows 3260 ft/min at 10k ft.

 

[Demetrious]

AF test run Oct 6, 1944, show SL rate of climb as 3180 ft/min. Max climb on another test, 44-1 fuel, shows 3260 ft/min at 10k ft.

Indeed. Perhaps I spoke too soon:

P-47-D test at ww2aircraftperformance.net:

C. Climbs

1. The service ceiling for 2700 RPM was 38,000 feet. The maximum rate of climb for 2700 RPM, 65.0" Hg., water injection was 3260 ft/min. at 10,000 feet. Without water at 65.0" Hg. the maximum rate of climb was 420 ft/min. less.

2. The rate of climb at 56.0" Hg., 2700 RPM, was 2330 ft/min. at 12,000 ft. and at 52.0" Hg., 2700 RPM, 2030 ft/min. at 12,000 ft.

 

[USS Enterprise CV-6]

Talk about a slug fest though, two brutes, heavy weights, with tremendous firepower and the ability to take a pounding.

I agree