Corsair and Hellcat in Europe

[Shortround6]

You're not missing anything. These early P-39s cruised at 25000' burning 54gph at normal/max continuous 2600rpm, although this chart shows it burning 71gph (120gal divided by 1.7hr). Remember this chart says "ALL PERFORMANCE ESTIMATED". Not a performance test, just guidelines.

It's only burning 54gph, want it to burn less at lower power?

Also remember the N model will be out in December with much better performance.

The engine was only burning 54 gallons an hour because that is all the air the supercharger could supply at 25,000ft at 2600rpm.

A test of a "D" showed 585hp at 25,000ft when climbing using 2600rpm. In level flight with more RAM and using 3000rpm the test plane showed 740hp at best power, 710 hp at auto lean and 695hp at auto rich. This is backwards from most aircraft and may show that the P-39s (at least on this test aircraft) carb was running too rich at high altitude.

The P-39 with 8.80 gears was simply running out of breath at these altitudes.

of course once the magic P-39N shows up in Dec after teleporting itself from Buffalo NY to Port Moresby (8,800 miles) the Japanese are doomed

 

[wuzak]

Spitfire V with 4 x 20mm cannon climbed to 20,000ft nearly 2 minutes faster than the P-39D. Standard Spitfire V was nearly 3 minutes faster.

 

[wuzak]

Why wasn't the pilot of the Airacobra given the option to operate at 25,000 feet at any power setting less than max continuous? Looks like he wasn't given the option to carry a drop tank or bomb at that height either. What am I missing here?

Hard to see in the chart, but looks like max cruise power was not available at 25,000ft, or at 10,000ft at or near maximum weight.

Would suggest there was not enough power to sustain level flight at max cruise power at 25,000ft. Even at max continuous power it seems to be only possible at 7,650lb.

Also note that at that weight the climb rate is only given for military power, and not for maximum continuous.

25,000ft is well above the critical altitude for the engine in Military Power, and probably for maximum continuous and maximum cruise as well.

The difference between the power levels is mostly due to rpm, which gives a slight increase to boost, due to increased supercharger rpm, as well. Can't recall the exact differences, but the Military power would be at 3,000rpm, max continuous at ~2,800rpm and max cruise at ~2,600rpm.

 

[parsifal]

Not meaningless. Just that on a mission where they had plenty of time to react, with aircraft operating at a known attack altitude, the P-39s were unable to reach that altitude. Your claim that there was no radar until august is disproven. Your claim that only radar could provide early warning, is disproven. Your claim that Milne Bay solved the detection issues over Moresby is patently incorrect, though not disproven .

It only takes one exception to disprove a theory expressed in absolutes. Your claims are completely busted by this one exception

But we can find plenty of other similar example for this dud of an aircraft if you want.

Something I forgot to correct earlier. the claim that the US forces were heavily outnumbered in the air in May 1942.

25th flotilla came under the command of 11 Air fleet, which from17 april was based on Tinian. At around that time,25th flotilla was reinforced with the elements of the Motoyama air gp (a special detachment that was originally to be attached to the 22 flotillain the SW command area, but wound up being attached to the Sth Seas detachment, less its fighter components. other commands under the 11AF included 24th 25th and 26th flotillas that were responsible for both the central and south pacific areas, the Carolines, the marianas and home islands defences.

As of 17 april there were 25 Zeroes in this TO, this was increased to 40 just before the end of the month.

Opposing them were the two fighter groups of the USAAC that tended to rotate the units as required. There were initially 60 a/c, give or take in the US FGs deployed, plus one RAAF fighter sqn . Nominally that amounted to about 80 fighters in front line, but at least as many again held in reserve. That is hardly "heavily outnumbered".

 

[Shortround6]

Can't recall the exact differences, but the Military power would be at 3,000rpm, max continuous at ~2,800rpm and max cruise at ~2,600rpm.

Military was 3000rpm, Max continuous was 2600rpm. max economical cruise was 2300rpm.
This is pretty much the same for P-39s, P-40s and P-38s with a few minor exceptions.

 

[wuzak]

Military was 3000rpm, Max continuous was 2600rpm. max economical cruise was 2300rpm.
This is pretty much the same for P-39s, P-40s and P-38s with a few minor exceptions.

Thanks.

So cruise power at 25,000ft must have been woeful if the power at max continuous was only 585hp.

The chart posted by eagledad suggests that the aircraft (P-39D) could not fly at 25,000ft in an overload condition (with bombs or external fuel tanks), meaning it had to make do with its 120USG internal fuel. Not great for range either.

 

[GregP]

I'm having a hard time seeing what a P-39 has to do with Hellcats and Corsairs in Europe. But I also didn't follow more than the last several pages.

 

[wuzak]

I'm having a hard time seeing what a P-39 has to do with Hellcats and Corsairs in Europe. But I also didn't follow more than the last several pages.

Particularly the performance of P-39s in the PTO!

 

[parsifal]

Particularly the performance of P-39s in the PTO!

The argument was raised by one member that he couldn't understand why the P-39 was not used as an escort in the ETO, and how well it flew against the Japanese opposition in the PTO.

 

[P-39 Expert]

My mistake. Got the interception and sighting times back the front. Airstrike was detected over Ioma (see map below) about 110 miles from target. There was an immediate scramble (AFAIK), which means the strike was intercepted somewhere over the owne Stanleys Despite all this early warning the p-39s were still not up to the correct altitude at the time of interception.


View attachment 503858

Am I ever getting to read your source myself? Can I get this from you?

If the Bettys were called in by coastwatchers (notoriously unreliable) at 110mi out and they cruised at 250mph then they would be at PM in .44hr or 26 min. Figure 15 minutes to take off, climb to altitude etc the 8th had 11 minutes to find two different groups of bombers at two different altitudes best case. Not including defending themselves against Zero escort. Harder than it looks.

Really would like to read your source.

 

[P-39 Expert]

The argument was raised by one member that he couldn't understand why the P-39 was not used as an escort in the ETO, and how well it flew against the Japanese opposition in the PTO.

Just said (and proved) that it could have been used as escort. Never said it was a P-51B.

 

[P-39 Expert]

Not meaningless. Just that on a mission where they had plenty of time to react, with aircraft operating at a known attack altitude, the P-39s were unable to reach that altitude. Your claim that there was no radar until august is disproven. Your claim that only radar could provide early warning, is disproven. Your claim that Milne Bay solved the detection issues over Moresby is patently incorrect, though not disproven .

It only takes one exception to disprove a theory expressed in absolutes. Your claims are completely busted by this one exception

But we can find plenty of other similar example for this dud of an aircraft if you want.

Something I forgot to correct earlier. the claim that the US forces were heavily outnumbered in the air in May 1942.

25th flotilla came under the command of 11 Air fleet, which from17 april was based on Tinian. At around that time,25th flotilla was reinforced with the elements of the Motoyama air gp (a special detachment that was originally to be attached to the 22 flotillain the SW command area, but wound up being attached to the Sth Seas detachment, less its fighter components. other commands under the 11AF included 24th 25th and 26th flotillas that were responsible for both the central and south pacific areas, the Carolines, the marianas and home islands defences.

As of 17 april there were 25 Zeroes in this TO, this was increased to 40 just before the end of the month.

Opposing them were the two fighter groups of the USAAC that tended to rotate the units as required. There were initially 60 a/c, give or take in the US FGs deployed, plus one RAAF fighter sqn . Nominally that amounted to about 80 fighters in front line, but at least as many again held in reserve. That is hardly "heavily outnumbered".

One group at the time, they were being rotated. 8th only had two squadrons until the 80th was added later.

A squadron was 16 planes per mission if no aborts. Total planes per squadron was about 24, crew chiefs had to keep 16 of those operational. So at any given time 32 planes were available for combat.

8th almost never sent up all 32 at once since a bad mission (bad weather etc) could see them all lost. Two flights (8 planes) on the runway with the rest in reserve.

Against as you say 40 Zeros and how many bombers? I would say that was outnumbered.

 

[P-39 Expert]

Hard to see in the chart, but looks like max cruise power was not available at 25,000ft, or at 10,000ft at or near maximum weight.

Would suggest there was not enough power to sustain level flight at max cruise power at 25,000ft. Even at max continuous power it seems to be only possible at 7,650lb.

Also note that at that weight the climb rate is only given for military power, and not for maximum continuous.

25,000ft is well above the critical altitude for the engine in Military Power, and probably for maximum continuous and maximum cruise as well.

The difference between the power levels is mostly due to rpm, which gives a slight increase to boost, due to increased supercharger rpm, as well. Can't recall the exact differences, but the Military power would be at 3,000rpm, max continuous at ~2,800rpm and max cruise at ~2,600rpm.

Maximum cruise power was 2600rpm and was available at all altitudes. May not have been much, but was available.

Military (combat) power was 3000rpm (740hp at 25000'), max continuous/normal was 2600rpm (585hp at 25000'). Using military power in climb greatly increased the climb rate over normal power.

 

[Shortround6]

If the Bettys were called in by coastwatchers (notoriously unreliable) at 110mi out and they cruised at 250mph then they would be at PM in .44hr or 26 min. Figure 15 minutes to take off, climb to altitude etc the 8th had 11 minutes to find two different groups of bombers at two different altitudes best case. Not including defending themselves against Zero escort. Harder than it looks.

Really would like to read your source.

I would really like to see the source that says the G4M Betty could cruise at 250mph??

 

[Dawncaster]

The Chance-Cought (actually Vought-Sikorsky ... all the drawings start with "VS" anyway) F4U Corsair gave the Japanese a nasty surprise. I was a very good fighter and, in its later versions, was simply outstanding by any measure of success of fighter prowess.

What do you think might have happened if it had been used in the ETO versus the Luftwaffe, combined with the all-time best kill ratio fighter of WWII, the F6F Hellcat? If the two of them had been deployed to Europe when they historically could have been, what might the result be?

It's OK to speculate the Pacific would not have gone as well without the two deployed in the same numbers as they were in real life, but remember the P-38 was there, too, and was not mach limited versus the Japanese in most cases.

Grumman's chief test pilot, Corky Meyer, has said in print (Flight Journal) that the Hellcat and Corsair flew side by side when at the same power levels when HE tested it except in the main stage (where it was 5 - 6 mph slower since the Hellcat didn't use ram air to avoid carburetor icing, and the same speed in low or high blower stages), and surmised the difference in airspeed was pitot tube placement on the Corsair since they verified the speed of the Hellcat with rigorous means. He says the Corsair was "optimistic" on airspeed and the Hellcat wasn't. Read the article ... but I can't remember the exact issue description. About 10 years ago or more, maybe 15 years ... can't remember.

I can't really say since our pilots at the Planes of Fame have never raced the two, but they fly side by side at the same power level when we DO fly them side by side (same rpm and MP). Same engine (basically, different dash number) and same prop in the early versions (same prop part number and diameter). Our Corsair is the oldest one in flying condition (tail number 799) and HAS the same prop as a Hellcat (F6F-3) ... and IT flies the same speed as a Hellcat at the same power levels in the same blower stages ± a few mph. Both gain or lose slightly, and not the same plane every time.

Corky seems to be right. What do you think?

Disagree, some founded facts were as follows.

The different IAS reads are not confined between F4U and F6F. It's common. Spitfire and Tempest also have different IAS reading tables, as were the P-47 and P-51, Yaks and MiGs, etc.... As he wrote at the end, he seems to have a little baised. Because he was a test pilot for Grumman, it seems he did not know about F4U as much as F6F. He called the tested F4U the latest version - F4U-1D, but it was late 1943, so it's different from the truth. BuNo 17781 was just F4U-1(F4U-1A) with old propeller blades. He said that both fighters 'SHOULD' have the same performance because they have the same engine, propeller, wing span, and gross weight. But In fact, the F4U had lighter gross weight and shorter wing span, the propeller blades and engine's altitude performances were also different. Well, If the F4U-1 was at a supercharger shift altitude and it had old propeller blades with early troublesome supercharged engine, it's not unusual for the F6F to be that fast - Especially If the F6F was less loaded and it's weight was light as F4U-1. However, most of the problems in F4U's engine were almost solved when F6F arrived on the solomon, and most of the flight tests were done with same load condition(ex. overload fighter), So F6F was generally slower than F4U in practical condition.

After the pitot tube error was resolved, the F6F-5 was became faster - it's true over 400mph class fighter, but still slower than the F4U-1A/D at all altitudes. Several comparison flights and mock dogfights, F4Us showed faster speed and higher climb rate. It's combat speed and combat climb with in actual ACM situation - no IAS reading influence.

On 22 April 1944, The Naval Air Forces Pacific Command received an F6F-5 and an F4U-1D for the purpose of fleet evalution. At the end of that time the board was generally agreed on most findings.

- F4U-1D is undoubtedly faster than F6F-5.
- F6F-5 has better maneuverability than F6F-3, but not better than F4U-1D.
- F4U-1D has better climb, especially zoom-climb characteristics than Grumman.
- F4U-1D is steadier gun platform and better dive bomber.
- F6F-5 is conceded easier to land aboard ship, owing to better foward visibility.

So, On 16 May 1944, a Navy evaluation board had concluded.

"It is the opinion of the board that generally the F4U is a better fighter, a better bomber and equally suitable carrier aircraft compared with the F6F. It is strongly recommended that the carrier fighter and or bomber complements be shifted to the F4U type."

It's clear why the Navy put the F4U on aircraft carrier. That's because the F4U-1D had the performance to meet the requirements of the Navy, not the limit of production capacity of Grumman - as someone often claims. Apart from the circumstances of the Grumman, the F4Us would have been on the aircraft carrier.

And present survival WWII fighters have different conditions so have to take that into account when making comparisons. For example, SETP's 1989 evalution, the FG-1D showed slower speed than F6F-5 until more than 130 seconds from start acceleration, due to F6F-5 had advantage in weight and drag condition. take off weight for F6F-5 was approx 2000 lbs lighter than military gross weight and clean wing without pylons, but FG-1D had only 1000 lbs lighter than military gross weight(Equivalent weight for military condition with 50% fuel and 50% ammunition - practical weight for combat) and fitted two stub pylons. Nevertheless, Corsair chosen for best in maneuverability, but under those conditions, Corsair could be said to be slower than Hellcat. It's the result of the difference in conditions.

References
1. Hellcat Versus the Corsair - 9 september to 8 November 1943 from 'Convair Advanced Designs: Secret Projects from San Diego, 1923-1962 '
2. Navy Taste Test: Hellcat vs Corsair from 'WW II Fighters From the Cockpit '
3. 'Whistling Death: The Test Pilot's Story of the F4U Corsair' by Boone T. Guyton
4. 'Vought F4U Corsair ' by Martin W. Bowman
5. 'Corsair: The F4U in World War II and Korea ' by Barrett Tillman
6. 'Flight Test Comparison: Ending the Argument ' by John M. Ellis III

 

[DarrenW]

I'm as bewildered as everyone else how this thread got so far off topic....

When I resurrected this thread I was curious about the performance gains that could be realized with the Corsair and Hellcat if 150 octane fuel was used in place of 130 (which was common practice in Europe by the summer of '44). After reading everyone's input and looking at performance charts I now see that for the most part it would only lower the critical altitude and have zero effect at the heights where strategic bombing was being performed.

I assumed wrongly that they would see the same gains as the Thunderbolt, forgetting that it's turbocharging unit had the ability to maintain constant sea-level horsepower well beyond normal escort fighter operating heights. However, the two navy fighters would obviously benefit from use of the fuel at low and medium altitudes.

So basically a 10-15 mph increase in speeds below FTH would occur but not much more (overall top speed obtained would not be very different). Climb rates would surely improve as well.

 

[Shortround6]

So basically a 10-15 mph increase in speeds below FTH would occur but not much more (overall top speed obtained would not be very different). Climb rates would surely improve as well.

The improved fuel would only affect the climb rates at altitudes below the Full Throttle Height (FTH) where the superchargers were not maxed out on airflow.
Once you are over the FTH the superchargers are maxed out, no more air available so no more boost and thus no more power regardless of fuel.

 

[DarrenW]

The improved fuel would only affect the climb rates at altitudes below the Full Throttle Height (FTH) where the superchargers were not maxed out on airflow.
Once you are over the FTH the superchargers are maxed out, no more air available so no more boost and thus no more power regardless of fuel.

Understood. Thanks.

 

[P-39 Expert]

I would really like to see the source that says the G4M Betty could cruise at 250mph??

What cruise speed would you prefer?

 

[stona]

What cruise speed would you prefer?

At least 50 mph lower.

Cheers

Steve