Corsair and Hellcat in Europe

P-39 Expert · Jul 23, 2018

DarrenW said:
What is the point that you're trying to make? The cruise speed of the Fort and Lib at bombing altitudes is still far lower than the cruise speeds of the majority of American fighters in service at the time (save for the P-39). I believe the points that SR6 has made thus far are still valid even while using your sources.

SR6 is saying that escort missions over Europe were not flown at normal power all the time. I'm saying that you had to PLAN your mission at normal power. If you could save a little gas here and there then great, you may land with a little spare gas left. Good for you. If not you still had enough fuel to fly your mission and get back to England because you planned for the worst case. This was the most heavily defended airspace in the world in '43-'44, you need ALL the speed and altitude your plane can muster. ALL the time.

P-39 (all models) was faster than either the B-17 or B-24. You honestly think a B-17 was faster than a P-39?

DarrenW · Jul 23, 2018

P-39 Expert said:
163gal available at 190gph normal power = .86hr x 225mph (bomber speed) = 195mi or call it a 100 mile radius. Not quite to the German border.

Are you disputing the escort ranges given here? I see about twice the radius of action from your calculations which would equate to half the fuel burn rate, which equates to cruise engine settings. I'm not even sure if they could make the French coast using your logic....

DarrenW · Jul 23, 2018

P-39 Expert said:
P-39 (all models) was faster than either the B-17 or B-24. You honestly think a B-17 was faster than a P-39?

At 25K feet who really knows? All the operating instructions that I've seen don't give a pilot the option to fly at that altitude while cruising around in an Airacobra.

Greyman · Jul 23, 2018

For what it's worth a British report on 8th Air Force escort tactics notes: "It is usual for the Bomber Force to fly at 18, to 25,000 feet, 150 m.p.h. A.S.I. ..."

P-39 Expert · Jul 23, 2018

DarrenW said:
Are you disputing the escort ranges given here? I see about twice the radius of action from your calculations which would equate to half the fuel burn rate, which equates to cruise engine settings. I'm not even sure if they could make the French coast using your logic....

View attachment 502994

For a P-47 to have a 230mi radius means a 460mi mission. After the reserves deducted in my post #359 that 460mi was on a net 163gal. At 225mph (bomber speed) meant a 2hr endurance which means burning 81gph. The smallest GPH figure listed in the P-47 range charts is 95gph for 200mph indicated or 300mph true. Burning 81gph (if you can stay aloft) would mean cruising at LESS THAN 300mph. Over the most heavily defended airspace in the world. It would be like trolling for sharks, you would be eaten in the first 10 minutes.

So yes, I guess I disagree with your charts.

P-39 Expert · Jul 23, 2018

DarrenW said:
At 25K feet who really knows? All the operating instructions that I've seen don't give a pilot the option to fly at that altitude while cruising around in an Airacobra.

P-39 pilots manual charts show the P-39N cruises at 344mph TAS at 25000'. 360mph for a P-47. A good deal faster than a B-17 at 220mph. Sheesh.

fubar57 · Jul 23, 2018

DarrenW · Jul 23, 2018

P-39 Expert said:
For a P-47 to have a 230mi radius means a 460mi mission. After the reserves deducted in my post #359 that 460mi was on a net 163gal. At 225mph (bomber speed) meant a 2hr endurance which means burning 81gph. The smallest GPH figure listed in the P-47 range charts is 95gph for 200mph indicated or 300mph true. Burning 81gph (if you can stay aloft) would mean cruising at LESS THAN 300mph. Over the most heavily defended airspace in the world. It would be like trolling for sharks, you would be eaten in the first 10 minutes.

So yes, I guess I disagree with your charts.

These escort ranges are well established, have been for years. I'm not saying that every mission profile allowed for these figures but the mission planners must of surely used something similar in order to make smart decisions concerning which units to use when and where. But if you refuse to admit that the P-47 normally flew escort between 280-300 mph TAS and totally refute the charts presented than there's really nothing more that can be said on the subject by yours truly. I'm tapping out....

DarrenW · Jul 23, 2018

P-39 Expert said:
P-39 pilots manual charts show the P-39N cruises at 344mph TAS at 25000'. 360mph for a P-47. A good deal faster than a B-17 at 220mph. Sheesh.

can I see this chart please?

DarrenW · Jul 23, 2018

....and obviously those are not under cruise settings (remember when I said "cruising around"?). In order for the Airacobra to fly at 25,000 feet it had to be in max continuous power all the time which ain't cruise!!!! Maybe that's why you are so determined to convince us that ALL fighters in the escort role flew at max continuous power, to level the playing field so to speak.

P-39 Expert · Jul 23, 2018

When did I say that?

P-39 Expert · Jul 23, 2018

DarrenW said:
....and obviously those are not under cruise settings (remember when I said "cruising around"?). In order for the Airacobra to fly at 25,000 feet it had to be in max continuous power all the time which ain't cruise!!!! Maybe that's why you are so determined to convince us that ALL fighters in the escort role flew at max continuous power, to level the playing field so to speak.

Max continuous/normal power (same thing) IS a cruise setting. It is 2550rpm for a Thunderbolt with 2700rpm for military/combat/TO power. You certainly could cruise at max continuous power, that is what it was for especially in the combat zone.

P-39/Allison max continuous/normal was 2600rpm with military/combat/TO power at 3000rpm. Max continuous/normal power IS CRUISE POWER. You can certainly cruise at lower power settings for increased fuel economy unless you want to get killed.

DarrenW · Jul 23, 2018

P-39 Expert said:
Max continuous/normal power (same thing) IS a cruise setting. It is 2550rpm for a Thunderbolt with 2700rpm for military/combat/TO power. You certainly could cruise at max continuous power, that is what it was for especially in the combat zone.

P-39/Allison max continuous/normal was 2600rpm with military/combat/TO power at 3000rpm. Max continuous/normal power IS CRUISE POWER. You can certainly cruise at lower power settings for increased fuel economy unless you want to get killed.

No hard feelings there P-39 guy. I hope you enjoy the fantasies you are creating concerning the sleek little fighter from Bell. I would be the last to take away any satisfaction you might derive from the experience.

DarrenW · Jul 23, 2018

And just so this thread doesn't get black balled, I will accept the idea that max continuous power can be construed as "cruise" by some and still be correct. Maybe you could tell me then why in other cruise "conditions" (lower power settings) there is no data for the P-39 above 20k feet in the operational charts?

I'm serious here, I want to learn something new.

Shortround6 · Jul 23, 2018

P-39 Expert said:
Janes listed the B-17 cruising speed at 220mph and B-24 at 237mph. That's about 150mph indicated. They were slow.

163gal available at 190gph normal power = .86hr x 225mph (bomber speed) = 195mi or call it a 100 mile radius. Not quite to the German border.

Jane's is good but it is not a pilot's manual. They are on this site, look them up. Milosh posted a link to one in post #357
ANd again, individual cruise speed is not formation cruise speed.

100 mile radius is far from the German border. It is 137 air miles from Harwich to Rotterdam. And yes that is about what they were rated for in WW II (if not 10-15 miles shorter) but then you forgot the fuel needed to get from 5000ft to 25,000ft. which was roughly another 50 gallons.

I think you are getting confused by the term "Normal power".

"Normal" and "max continuous" are the same. It was supposed to be the maximum power that could be used without a time limit, Not a cruise power.

I would note it was not all roses and chocolate for the defending Germans, after climbing to 25,000 ft or above they were at best climb speed and not anywhere near max level speed or even max level cruise speed and they would need around 2 minutes (4-6 miles?) to accelerate from best climb speed to a high level speed. The American escort fighters were cruising at around 1/2 between best climb speed and full speed.

wuzak · Jul 23, 2018

I would expect that the use of normal/max continuous power would give the aircraft its maximum cruise speed.

But on a mission requiring range it would not be the best to use, except for areas with a very high chance of enemy contact.

They would use a cruise setting which is a compromise between range and cruise speed.

Greyman · Jul 23, 2018

British data sheets for P39 N1 to N5 (Allison V1710-85 [E19]) have:

Cruising Speed (most economical) 15,000 feet: 215 mph
Cruising Speed (max weak mix) 15,000 feet: 296 mph

Shortround6 · Jul 23, 2018

The American "Normal" or max continuous was similar to the British max cruise. The Americans never used a 30 minute climb rating, although early in the war a few of the engines were only supposed to use the Normal or max continuous for 1 hour.

wuzak · Jul 23, 2018

Greyman said:
British data sheets for P39 N1 to N5 (Allison V1710-85 [E19]) have:

Cruising Speed (most economical) 15,000 feet: 215 mph
Cruising Speed (max weak mix) 15,000 feet: 296 mph

For an escort mission over Europe, they would use maximum weak mixture most of the time.

For comparison:
Mustang Mk III with V-1650-3:
Cruising Speed (most economical) 20,000 feet: 253 mph
Cruising Speed (max weak mix) 20,000 feet: 395 mph
http://www.wwiiaircraftperformance.org/mustang/mustang-III-ads-3.jpg

Mustang Mk III with V-1650-7:
Cruising Speed (most economical) 20,000 feet: 253 mph
Cruising Speed (max weak mix) 20,000 feet: 405 mph
http://www.wwiiaircraftperformance.org/mustang/mustang-III-ads-7.jpg

F4U-1:
Cruising Speed (most economical) 20,000 feet: 251 mph
Cruising Speed (max weak mix) 20,000 feet: 281 mph
http://www.wwiiaircraftperformance.org/f4u/f4u-1-ads.jpg

F4U-1a:
Cruising Speed (most economical) 20,000 feet: 248 mph
Cruising Speed (max weak mix) 20,000 feet: 278 mph
http://www.wwiiaircraftperformance.org/f4u/f4u-1a-ads.jpg

Corsair IV:
Cruising Speed (most economical) 20,000 feet: 261 mph
Cruising Speed (max weak mix) 20,000 feet: 300 mph
http://www.wwiiaircraftperformance.org/f4u/corsair-IV-ads.jpg

Hellcat I:
Cruising Speed (most economical) 20,000 feet: 232 mph
Cruising Speed (max weak mix) 20,000 feet: 282 mph
http://www.wwiiaircraftperformance.org/f6f/hellcat-I-ads-a.jpg

Hellcat II:
Cruising Speed (most economical) 20,000 feet: 237 mph
Cruising Speed (max weak mix) 20,000 feet: 293 mph
http://www.wwiiaircraftperformance.org/f6f/hellcat-II-ads-a.jpg

Mosquito Mk IV with Merlin 21:
Cruising Speed (most economical) 15,000 feet: 265 mph
Cruising Speed (max weak mix) 15,000 feet: 320 mph
http://www.wwiiaircraftperformance.org/mosquito/Mosquito_MkIV-merlin21_ads.jpg

Mosquito Mk IV with Merlin 23:
Cruising Speed (most economical) 15,000 feet: 265 mph
Cruising Speed (max weak mix) 15,000 feet: 327 mph
http://www.wwiiaircraftperformance.org/mosquito/Mosquito_MkIV_ads.jpg

Mosquito Mk XVI with Merlin 72/73:
Cruising Speed (most economical) 15,000 feet: 245 mph
Cruising Speed (max weak mix) 15,000 feet: 311 mph (321mph after dropping wing bombs)
http://www.wwiiaircraftperformance.org/mosquito/Mosquito_MkXVI_ads.jpg

DarrenW · Jul 23, 2018

Greyman said:
British data sheets for P39 N1 to N5 (Allison V1710-85 [E19]) have:

Cruising Speed (most economical) 15,000 feet: 215 mph
Cruising Speed (max weak mix) 15,000 feet: 296 mph

Shortround6 said:
The American "Normal" or max continuous was similar to the British max cruise. The Americans never used a 30 minute climb rating, although early in the war a few of the engines were only supposed to use the Normal or max continuous for 1 hour.

wuzak said:
I would expect that the use of normal/max continuous power would give the aircraft its maximum cruise speed.

But on a mission requiring range it would not be the best to use, except for areas with a very high chance of enemy contact.

They would use a cruise setting which is a compromise between range and cruise speed.

I'm starting to get the impression that "max continuous" power as well as the lowest cruise settings possible are not the most ideal of choices, except under extreme circumstances.

How much time would a P-47D need to accelerate from let's say 300mph up to it's maximum speed at full military power? And I think SR6 made a good point. Why is it always assumed by some people that the Luftwaffe was that good at vectoring interceptors in order to catch the escort fighters with their proverbial pants down around their ankles? They had their own laundry list of obstacles to overcome just to make it to altitude and show up in the same piece of sky at the same time as the bombers they were bent on destroying.

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