Planes that are simultaneously both the most over rated and the most under rated.

[Shortround6]

As long as we're comparing ranges, at what altitude and external fuel load will we be using?

How about several conditions?

Say clean at 12,000 or15,000ft at most economical and then with a normal (not ferry) external tank,
then at a higher speed both with and without tank

or pick different altitude.

Or pick 3 different speed/altitude combinations.

 

[Milosh]

Don't know why the image won't show.

anyways, http://zenoswarbirdvideos.com/Images/P-39/P39FOIC.pdf

 

[Shortround6]

In general the P-39s (with 120 US gallons of fuel) were rated at around 600 miles or bit more in those charts at the IAS of just over 200mph at the lower altitudes (Chart for a K/L is incomplete and doesn't show anything over 12,000ft in that column). The Chart at Zenos is for one of the Qs with reduced fuel tankage, add about 50% to the ranges given. 70 gallons becomes 105 gallons and figure about 15 gallons for warm up and take-off,
Chart for the K/L only goes to 9,000ft in that column when carrying a 75 gallon drop tank (170 gallons useable fuel figured for the range) and the range was given as 828 miles at 169 mph IAS at that altitude. Unfortunately the only column in the chart is for max continuous power which was hardly realistic. 2600 rpm and either full boost at the higher altitudes or 37.5in at the lower ones. range was 435 miles with the 75 gallon tank at a speed of about 285-8mph true at 9-15,000ft. without the tank range was 300 miles and speed was 340-348mph true at the same altitudes.

I will note that for some reason unknown to me, the chart for the P-39K/L shows 20 gallons being used for warm and take-off when clean, 25 gallons are used for the same when carrying the drop tank and 16 gallons are used on the P-39Q for the same procedure, adjust as you see fit.

 

[P-39 Expert]

In general the P-39s (with 120 US gallons of fuel) were rated at around 600 miles or bit more in those charts at the IAS of just over 200mph at the lower altitudes (Chart for a K/L is incomplete and doesn't show anything over 12,000ft in that column). The Chart at Zenos is for one of the Qs with reduced fuel tankage, add about 50% to the ranges given. 70 gallons becomes 105 gallons and figure about 15 gallons for warm up and take-off,
Chart for the K/L only goes to 9,000ft in that column when carrying a 75 gallon drop tank (170 gallons useable fuel figured for the range) and the range was given as 828 miles at 169 mph IAS at that altitude. Unfortunately the only column in the chart is for max continuous power which was hardly realistic. 2600 rpm and either full boost at the higher altitudes or 37.5in at the lower ones. range was 435 miles with the 75 gallon tank at a speed of about 285-8mph true at 9-15,000ft. without the tank range was 300 miles and speed was 340-348mph true at the same altitudes.

I will note that for some reason unknown to me, the chart for the P-39K/L shows 20 gallons being used for warm and take-off when clean, 25 gallons are used for the same when carrying the drop tank and 16 gallons are used on the P-39Q for the same procedure, adjust as you see fit.

I believe you are looking at the P-39K/L manual, the Q manual's numbers are a little better.

The following do not include any reserve for combat (15min) or landing (20min).

FERRY:
P-47 At 15000' clean with 260gal internal fuel (305-45 reserve for take off and climb) at 90gallons per hour gave 2.9 hours before deducting any reserves for combat or landing.
P-39 At 15000' clean with 104gal internal (120-16 RTOC) at 41gph gave 2.5hrs before reserves. P-47 had .4hr or 24minutes more.
P-47 At 15000' with 110gal drop tank 370gal total (305+119=414-45reserve=370gal) at 90gph gave 4.1hr.
P-39 At 15000' with 110gal drop tank 210gal total (120+110-20reserve=210gal) at 41gph gave 5.1hr. P-39 had an hour more.

COMBAT:
P-47 At 25000' with 110gal drop tank 370gal total at 190gph max continuous gave 1.9hr. The most economical setting of 105gph gave 3.5hrs.
P-39 At 25000' with 110 gal drop tank 210gal total at 62gph max continuous gave 3.4hrs. About the same as the P-47 most economical setting.

The engine chart for the P-47 shows 210gph max continuous at 29000' but the range charts use 190gph.

Please remember that the P-39N was out of production before the P-47 got into combat in May '43. And the P-47 had absolutely no provision for any drop tank before August '43.

 

[Dimlee]

The top 58 Stuka pilots on the Russian Front eliminated some 3,700 Soviet tanks

They claimed to eliminate some 3,700 tanks, did not they.
And since Ju 87G arrived to the front line in July 1943 and most of the time after that the Germans were in retreat and there were less and less possibilities to check those claims...

 

[Dimlee]

Some over/under rated names from the Eastern Front which come to mind immediately.

Il-2 - probably the most famous VVS aircraft of WWII, continuously hyped in the Soviet literature until the archives became available to independent researchers in 1990s... Since then many questions were raised about real (not imaginative) ruggedness, weapons effectiveness, easiness to handle, reliability, etc. But old myths still persist and in modern Russian language aviation sources one can find absolutely contradictory opinions, sometimes in the same article or book chapter.

P-39 - somewhat underrated in the "West" and mildly overrated in the "East". Its strong and weak sides have been discussed extensively on this forum, so no need to go into details now. Just to note that the Soviet "overrating" was done in very specific way, when the aircraft type was rarely mentioned (for political reasons) but names of pilots publicised widely and their tactical methods and combat results glorified.

Su-2 - underrated to the level of condemnation and disdain in the Soviet period. Later researches have cleared many misconceptions and have shown very interesting aircraft which was instrumental in various roles and was phased out not because it was "bad" (as repeatedly said earlier) but due to production troubles and (possibly) political reasons. New information brought many "what if" ideas into life and caused not only delayed positive appraisal but also claims about Su-2 as potentially the best CAS aircraft of VVS - if only...

 

[pinehilljoe]

Some over/under rated names from the Eastern Front which come to mind immediately.

Il-2 - probably the most famous VVS aircraft of WWII, continuously hyped in the Soviet literature until the archives became available to independent researchers in 1990s... Since then many questions were raised about real (not imaginative) ruggedness, weapons effectiveness, easiness to handle, reliability, etc. But old myths still persist and in modern Russian language aviation sources one can find absolutely contradictory opinions, sometimes in the same article or book chapter.

P-39 - somewhat underrated in the "West" and mildly overrated in the "East". Its strong and weak sides have been discussed extensively on this forum, so no need to go into details now. Just to note that the Soviet "overrating" was done in very specific way, when the aircraft type was rarely mentioned (for political reasons) but names of pilots publicised widely and their tactical methods and combat results glorified.

Su-2 - underrated to the level of condemnation and disdain in the Soviet period. Later researches have cleared many misconceptions and have shown very interesting aircraft which was instrumental in various roles and was phased out not because it was "bad" (as repeatedly said earlier) but due to production troubles and (possibly) political reasons. New information brought many "what if" ideas into life and caused not only delayed positive appraisal but also claims about Su-2 as potentially the best CAS aircraft of VVS - if only...

I'm very skeptical of all the figures from the Soviet era, aircraft production, tank production, air to ground kills.

 

[Shortround6]

Endurance is not necessarily range.

The P-47 at 200mph IAS at 12,000ft burns 65 gals of fuel an hour and has a range of 880 miles no reserve for combat (15min) or landing (20min).
The P-39K at 193mph IAS at 12,000ft burns 33 gph and has a range of 640 miles. no reserve for combat (15min) or landing (20min).
The P-39Q at 207mph IAS at 12,000ft burns 37gph and would have a range of 645 miles on 105 gallons of internal fuel.

I am not seeing the superiority of the P-39 in range at these low speeds?

I really love the way you left out the speeds a which you made the comparisons. One might think that would be an important consideration?

Like an early clean P-47 can cruise at about 225mph IAS at 25,000ft burning 145 gph? and 225mph IAS is about 337mph true depending on the conversion you use. later charts agree pretty well, a P-47D-25 using 143gph to go 324mph true at 25,000ft without tanks, I don't know if the loss of speed from the early aircraft is due to a different conversion factor, more flight testing, drag from the bubble canopy or drag from the underwing bomb/tank racks.

P-39 trying to cruise at 25,000ft is like trying to cruise a canoe by paddling upstream, The P-39's engine is struggling to maintain desired cruising speed and has little power left in reserve.
Why is the plane only burning 62 gph at 25,000ft when it burned 104gph at 15,000ft at the same rpm and throttle setting? because the supercharger simply won't provide enough air to burn any more fuel at 2600rpm and a wide open throttle. engine is making under 600hp in this situation. off course the engine only makes around 775hp at full throttle at 25,000ft so pilots options are a bit limited.

 

[Greg Boeser]

Another (oft-forgot) issue with the Buffalo is that its manuevering characteristics changed a lot based on version. The Finns got the first, spritely version (F2A-1 equivalent). The Dutch and the British got the F2A-2, with more guns but no more horsepower. It was used in the Far East and did not fare well vs Japanese A6M2s. The US had ordered a few of each of these, but ordered the F2A-3 with heavier guns, armor, and carrier landing equipment was even less maneuverable, and did not do well against the agile - nor did it stack up well against a new contender from Grumman - F4F Wildcat, which began to replace it as quickly as it could be produced.

unkated

Hey, fancy meeting you here!

 

[P-39 Expert]

Endurance is not necessarily range.

The P-47 at 200mph IAS at 12,000ft burns 65 gals of fuel an hour and has a range of 880 miles no reserve for combat (15min) or landing (20min).
The P-39K at 193mph IAS at 12,000ft burns 33 gph and has a range of 640 miles. no reserve for combat (15min) or landing (20min).
The P-39Q at 207mph IAS at 12,000ft burns 37gph and would have a range of 645 miles on 105 gallons of internal fuel.

I am not seeing the superiority of the P-39 in range at these low speeds?

I really love the way you left out the speeds a which you made the comparisons. One might think that would be an important consideration?

Like an early clean P-47 can cruise at about 225mph IAS at 25,000ft burning 145 gph? and 225mph IAS is about 337mph true depending on the conversion you use. later charts agree pretty well, a P-47D-25 using 143gph to go 324mph true at 25,000ft without tanks, I don't know if the loss of speed from the early aircraft is due to a different conversion factor, more flight testing, drag from the bubble canopy or drag from the underwing bomb/tank racks.

P-39 trying to cruise at 25,000ft is like trying to cruise a canoe by paddling upstream, The P-39's engine is struggling to maintain desired cruising speed and has little power left in reserve.
Why is the plane only burning 62 gph at 25,000ft when it burned 104gph at 15,000ft at the same rpm and throttle setting? because the supercharger simply won't provide enough air to burn any more fuel at 2600rpm and a wide open throttle. engine is making under 600hp in this situation. off course the engine only makes around 775hp at full throttle at 25,000ft so pilots options are a bit limited.

Endurance is not necessarily range.

The P-47 at 200mph IAS at 12,000ft burns 65 gals of fuel an hour and has a range of 880 miles no reserve for combat (15min) or landing (20min).
The P-39K at 193mph IAS at 12,000ft burns 33 gph and has a range of 640 miles. no reserve for combat (15min) or landing (20min).
The P-39Q at 207mph IAS at 12,000ft burns 37gph and would have a range of 645 miles on 105 gallons of internal fuel.

I am not seeing the superiority of the P-39 in range at these low speeds?

I really love the way you left out the speeds a which you made the comparisons. One might think that would be an important consideration?

Like an early clean P-47 can cruise at about 225mph IAS at 25,000ft burning 145 gph? and 225mph IAS is about 337mph true depending on the conversion you use. later charts agree pretty well, a P-47D-25 using 143gph to go 324mph true at 25,000ft without tanks, I don't know if the loss of speed from the early aircraft is due to a different conversion factor, more flight testing, drag from the bubble canopy or drag from the underwing bomb/tank racks.

P-39 trying to cruise at 25,000ft is like trying to cruise a canoe by paddling upstream, The P-39's engine is struggling to maintain desired cruising speed and has little power left in reserve.
Why is the plane only burning 62 gph at 25,000ft when it burned 104gph at 15,000ft at the same rpm and throttle setting? because the supercharger simply won't provide enough air to burn any more fuel at 2600rpm and a wide open throttle. engine is making under 600hp in this situation. off course the engine only makes around 775hp at full throttle at 25,000ft so pilots options are a bit limited.

I said the P-39 range was similar to the P-47, not superior. The comparison was ferrying at 15000' and combat at 25000'. Use 12000' if you want.

Speeds were similar. Ferrying clean showed the P-47 at 215 (IAS) and the P-39 at 204, with drop tank the P-47 at 191 and the P-39 at 170.
Combat at 25000' showed the P-47 at 215 at less than normal power and 190 at most economical, with the P-39 at 187.

P-39N cruised just fine at 25000' with a drop tank. Cruising speed was 187 IAS with minimum cruising speed of 170 so an even lower power setting (more endurance) could have been used if needed. Drop the tank for combat and power was still adequate to climb at almost 2000fpm at 25000' which was still better than the clean P-47. P-47 was faster, P-39 had better climb, endurance was about the same.

 

[AlfaKiloSierra]

As long as we're comparing ranges, at what altitude and external fuel load will we be using?

P-39 at 10100ft has a range of 430mi with 70 US gal of fuel [1], but that is not the full fuel capacity. P-39 has an internal fuel of 150 US gal [2], but 16 US gal unusable [1], which by estimation gives it at most 823mi of range*. With droptanks the P-39 cannot compare to the P-47 that has droptanks.
[1] http://www.wwiiaircraftperformance.org/P-39/P-39_Aircraft_Performance_Characteristics.jpg Pg. 24 of document, Pg. 30 of pdf file
[2] Bell P-39 Airacobra - The Big Omnipedia

P-47D-25 at 10100ft with 370 US gal has range of 1030mi, using optimal cruise power [3]. This is the maximum internal fuel of P-47D-25 [4].
[3] http://www.wwiiaircraftperformance.org/p-47/p-47-tactical-chart.jpg
[4] The Republic P-47 Thunderbolt

*The P-39 at 70 US gal usable fuel has a range of 430mi, for 6.14 mi/gal. At 60 US gal usable fuel, it has a range of 370mi, for 6.17 mi/gal. Implying that the range/fuel ratio may slightly decrease as fuel increases.

 

[AlfaKiloSierra]

I said the P-39 range was similar to the P-47, not superior. The comparison was ferrying at 15000' and combat at 25000'. Use 12000' if you want.

Speeds were similar. Ferrying clean showed the P-47 at 215 (IAS) and the P-39 at 204, with drop tank the P-47 at 191 and the P-39 at 170.
Combat at 25000' showed the P-47 at 215 at less than normal power and 190 at most economical, with the P-39 at 187.

P-39N cruised just fine at 25000' with a drop tank. Cruising speed was 187 IAS with minimum cruising speed of 170 so an even lower power setting (more endurance) could have been used if needed. Drop the tank for combat and power was still adequate to climb at almost 2000fpm at 25000' which was still better than the clean P-47. P-47 was faster, P-39 had better climb, endurance was about the same.

P-47D climb rate stays above 2000ft/min until 27500ft, and at 25000ft the P-47D has a climb rate of almost 2400ft/min [1].
http://www.wwiiaircraftperformance.org/p-47/p47d-44-1-climb.jpg

P.S. There are certainly altitudes at which the P-39 climbs much better, but that's not 25000ft.

 

[P-39 Expert]

P-47D climb rate stays above 2000ft/min until 27500ft, and at 25000ft the P-47D has a climb rate of almost 2400ft/min [1].
http://www.wwiiaircraftperformance.org/p-47/p47d-44-1-climb.jpg

P.S. There are certainly altitudes at which the P-39 climbs much better, but that's not 25000ft.

You are comparing a P-39N from late '42 to a P-47D from July '44 (after air superiority had been won) using an experimental fuel that was not even in service yet. The P-39N outclimbed all production P-47s at all altitudes in '43 and early '44. Pretty good for a little single stage Allison.

 

[P-39 Expert]

P-39 at 10100ft has a range of 430mi with 70 US gal of fuel [1], but that is not the full fuel capacity. P-39 has an internal fuel of 150 US gal [2], but 16 US gal unusable [1], which by estimation gives it at most 823mi of range*. With droptanks the P-39 cannot compare to the P-47 that has droptanks.
[1] http://www.wwiiaircraftperformance.org/P-39/P-39_Aircraft_Performance_Characteristics.jpg Pg. 24 of document, Pg. 30 of pdf file
[2] Bell P-39 Airacobra - The Big Omnipedia

P-47D-25 at 10100ft with 370 US gal has range of 1030mi, using optimal cruise power [3]. This is the maximum internal fuel of P-47D-25 [4].
[3] http://www.wwiiaircraftperformance.org/p-47/p-47-tactical-chart.jpg
[4] The Republic P-47 Thunderbolt

*The P-39 at 70 US gal usable fuel has a range of 430mi, for 6.14 mi/gal. At 60 US gal usable fuel, it has a range of 370mi, for 6.17 mi/gal. Implying that the range/fuel ratio may slightly decrease as fuel increases.

My information is from the pilot manuals for both the P-39Q (adjusted to P-39N figures) and the P-47B/C/D. P-39 fuel capacity 120 gal internal and a 110gal drop tank.

 

[michael rauls]

You are comparing a P-39N from late '42 to a P-47D from July '44 (after air superiority had been won) using an experimental fuel that was not even in service yet. The P-39N outclimbed all production P-47s at all altitudes in '43 and early '44. Pretty good for a little single stage Allison.

Does all altitudes include abouve 30,000 feet. I was under the impression the p47 outperforms pretty much everything abouve 30,000 feet, the turbo charger and all.

 

[Shortround6]

You are comparing a P-39N from late '42 to a P-47D from July '44 (after air superiority had been won) using an experimental fuel that was not even in service yet. The P-39N outclimbed all production P-47s at all altitudes in '43 and early '44. Pretty good for a little single stage Allison.

My information is from the pilot manuals for both the P-39Q (adjusted to P-39N figures) and the P-47B/C/D. P-39 fuel capacity 120 gal internal and a 110gal drop tank.

We are back to the magic P-39N that could outclimb (by hundreds of feet per minute) any other P-39 of any model.

Of course it did this (in part) by flying hundreds of pounds lighter than any other P-39 model.

You can't have it both ways, you either have the good climb of a light P-39 and not enough fuel to get home or you have enough fuel and the less than steller climb.

A P-39Q-5 using the same engine as the P-39N was climbing at 1570fpm at 25,000ft. The early P-47s with tooth pick props and no water injection could climb around 1800fpm.

 

[AlfaKiloSierra]

My information is from the pilot manuals for both the P-39Q (adjusted to P-39N figures) and the P-47B/C/D. P-39 fuel capacity 120 gal internal and a 110gal drop tank.

The P-39 has two 60 US gal tanks in each wing, and a 30 US gal reserve tank in the left wing according to some sources. The P-47 range varies on variants, the earlier P-47s may have range similar to the P-39 or even inferior, but the P-47D-25 is definitely superior, especially with droptanks.

 

[AlfaKiloSierra]

You are comparing a P-39N from late '42 to a P-47D from July '44 (after air superiority had been won) using an experimental fuel that was not even in service yet. The P-39N outclimbed all production P-47s at all altitudes in '43 and early '44. Pretty good for a little single stage Allison.

What about a 56" P-47 instead of that 70" one I used
http://www.wwiiaircraftperformance.org/p-47/p47d-44-1-climb.jpg
Slightly over 2000ft/min at 25000ft.

Again, the P-39 significantly out-climbs the P-47 at low altitude, but stop saying it outclimbs P-47 at an altitude the P-39 is suffering from its single-stage supercharger.

 

[Shortround6]

The P-39 has two 60 US gal tanks in each wing, and a 30 US gal reserve tank in the left wing according to some sources. The P-47 range varies on variants, the earlier P-47s may have range similar to the P-39 or even inferior, but the P-47D-25 is definitely superior, especially with droptanks.

Sources are screwed up.

There is a 60 gallon tank in each wing (actually 6 interconnected tanks/fuel cells ) of 60 gallons total in each wing (unless you have one of the stripper models with 86-87 gallons total.

The confusion comes in with "reserve". most American planes (and some others) had one fuel tank with two outlets, the other tank/s had one outlet. On the tank with two outlets the fuel was taken at different heights in the tank. On the P-39 the usual reserve was 16-20 gallons, when the fuel selector was set to the left tank the 60 gallons went down to about 16-20 gallons left in the tank below the pick up point. On the right tank all of the fuel was useable (except for 1-2 gallons?) then pilot switched to "reserve" which used the lower pick up point in the left tank and used that 16-20 gallons.

There was no separate tank and "reserve" fuel was part of the total. This was true of the P-51 and the P-40 and most other US fighters. P-47 were supposed to operate this way but didn't, a pilot who read the manual kept a few gallons (10 or more) in each fuselage tank just in case.

At similar speeds and altitudes a clean P-47 always had more range than a clean P-39. Clean P-47 vs P-39 with drop tank is a different story but then a P-47 with drop tank/s gets a sizable boost in range/radius too, obviously depending on the size of the tank/s.

 

[AlfaKiloSierra]

Sources are screwed up.

There is a 60 gallon tank in each wing (actually 6 interconnected tanks/fuel cells ) of 60 gallons total in each wing (unless you have one of the stripper models with 86-87 gallons total.

The confusion comes in with "reserve". most American planes (and some others) had one fuel tank with two outlets, the other tank/s had one outlet. On the tank with two outlets the fuel was taken at different heights in the tank. On the P-39 the usual reserve was 16-20 gallons, when the fuel selector was set to the left tank the 60 gallons went down to about 16-20 gallons left in the tank below the pick up point. On the right tank all of the fuel was useable (except for 1-2 gallons?) then pilot switched to "reserve" which used the lower pick up point in the left tank and used that 16-20 gallons.

There was no separate tank and "reserve" fuel was part of the total. This was true of the P-51 and the P-40 and most other US fighters. P-47 were supposed to operate this way but didn't, a pilot who read the manual kept a few gallons (10 or more) in each fuselage tank just in case.

At similar speeds and altitudes a clean P-47 always had more range than a clean P-39. Clean P-47 vs P-39 with drop tank is a different story but then a P-47 with drop tank/s gets a sizable boost in range/radius too, obviously depending on the size of the tank/s.

Thank you for the explanation