P-38 vs P-51

[CORSNING]

Shall we do a thread P-39 vs P-47?

No need FLYBOY, we just had one.

 

[P-39 Expert]

You were using the wrong numbers. A few of the instructions do not apply, The P-39 had no WEP rating for 5 minutes at high altitude, the supercharger couldn't supply the boost needed to hit or even exceed military power at these altitudes. The P-47 wouldn't get WEP rating until it got water injection. So I used 20min at military power instead of 15min military and 5min WEP. The numbers are absolutely comparable.



As Tomo has explained, it won't go fast enough with the drop tank attached. One reason for the 210IAS requirement was so that the fighters were running closer to high speed if they had to respond to a group of incoming fighters. If you are running too slow in order to get good gas mileage you might as well not be there. It takes a bit of time to drop the tanks an accelerate from 310-315mph true to somewhere near 400mph even if the T-Bolt never got to top speed. If you are starting from 267-270mph when you drop the tank it takes that many seconds longer just to get up to the 310-315 the T-Bolts started with and then get to what speed the P-39 can manage. please note the P-47 has a much better power to weight ratio at 25,000 ft than the P-39 does. I have read a few of those tests and there is no 210IAS requirement. The tests used the actual speed of the test plane. The tank is dropped before combat and at that point altitude is more important than speed.



If you want the climb rate of the 87 gallon planes you have to take the range problems of the 87 gallon planes. You can't have it both ways. No way to know for sure, but that actual plane tested was a P-39K with the N engine/reduction gear/propeller. The K model all had 120gal internal. Not wanting it both ways, just don't compare the N and the Q. Q got heavier and the external guns created drag.

you want to play games with guns and ammo? I wonder How a P-47 does with only six guns and 200 round per gun?

 

[P-39 Expert]

P-39N first entered service with free French in North Africa in April 1943.
P-47C first became operational with the 8th A.F. on 8 April 1943.
I do not have a complete test report on the "C" so for the following
performance comparisons I am using the earliest full test of an Operational
P-47 that I have been able to acquire thanks to www.wwiiaircraftperformanc.org


Quick reference using figures for P-47D-10 42-75035 and (P-39N 42-4400).
Altitude / Speed / Climb
Meters / MPH / FPM
SL.......333/2870 (344/3980)
1000..347/2850 (362/4145)
2000..357/2770 (381/4220)
3000..372/2690 (398/3940)
4000..383/2550 (394/3460)
5000..394/2400 (388/3060)
6000..404/2200 (382/2685)
7000..414/2000 (376/2230)
8000..423/1770 (367/1745)
9000..430/1420 (356/1310)

Range:
Internal fuel: 640 ml. (360 ml./87 gal. - 525 ml./120 gal.)
Max. External: 925-1250 ml. (1075 ml. with 120 gal. internal +175 gal. external)
Note: The P-39N and P-30Q-1 were constructed with the 87 gallon internal tank at
the factory. However there was a kit available to bring the capacity to 120 gallons
if desired. It should also be noted that the above performance of the P-39N would
suffer some with the added fuel.

Take-off weight: 13,234 (7,301) lb.

Minimum turn time: 22.6-26 (19.0) seconds to complete a 360 degree turn.

Maximum roll rate: 85 degrees/sec./250 mph. (75 degrees/sec./235 mph.)
Note: The numbers for roll rate are for P-47D-30 (P-39D-1)

Excellent work. Did you notice the climb numbers were substantially higher for the P-39N at all altitudes up to 8000meters (26400')?

 

[Dan Fahey]

True and agree, but that argument is mute when the Mustang has a catastrophic engine failure after taking flack, double the point if over a vast body of water.

This is a myth.
P38's loss of an engine would not survive any better.
The asymmetry of the remaining engine would flip over the aircraft.
A pilot would have to be lucky and have enough altitude to correct for this.

Another P38 Achilles Heal was combat damage to the rear Elevator.

 

[CORSNING]

you want to play games with guns and ammo? I wonder How a P-47 does with only six guns and 200 round per gun?[/QUOTE]

My Bad guys. The figures I used for the P-47-10 came from a report dated 11 Oct. '43.
In the A. Purpose section it states:
"1. To report results of flight tests on P-47D-10 airplane, AAF No. 43-75035 run at the
manufacturer's plant. Airplane equipped with Pratt & Whitney R-2800-63 engine with
water injection; standard Curtiss 714-1C2-12 propeller; type A-17 turbo regulator. Airplane
ballasted to simulate the following conditions: Six .50 caliber guns; 300 rounds per gun;
305 gallons gasoline; 15 gallons water; 14 pounds pyrotechnics. In this condition the gross
weight was 13,234 pounds with a C.G. wheels up, of 29.63 percent M.A.C. Mixture auto-
rich; throttle wide open on all tests. Horsepower data obtained with torquemeter."

I was actually shooting for an earlier version without the water injection and 8 guns.

 

[DerAdlerIstGelandet]

This is a myth.
P38's loss of an engine would not survive any better.
The asymmetry of the remaining engine would flip over the aircraft.
A pilot would have to be lucky and have enough altitude to correct for this.

Another P38 Achilles Heal was combat damage to the rear Elevator.

Well this is going to get interesting...

 

[Shortround6]

This is a myth.
P38's loss of an engine would not survive any better.
The asymmetry of the remaining engine would flip over the aircraft.
A pilot would have to be lucky and have enough altitude to correct for this.

MIght be interesting trying to explain to some pilots in the CBI theater who made it back up to 600 miles on one engine why the couldn't have done it.
Maybe they were hit at high altitude?

 

[Shortround6]

you want to play games with guns and ammo? I wonder How a P-47 does with only six guns and 200 round per gun?

My Bad guys. The figures I used for the P-47-10 came from a report dated 11 Oct. '43.
In the A. Purpose section it states:
"1. To report results of flight tests on P-47D-10 airplane, AAF No. 43-75035 run at the
manufacturer's plant. Airplane equipped with Pratt & Whitney R-2800-63 engine with
water injection; standard Curtiss 714-1C2-12 propeller; type A-17 turbo regulator. Airplane
ballasted to simulate the following conditions: Six .50 caliber guns; 300 rounds per gun;
305 gallons gasoline; 15 gallons water; 14 pounds pyrotechnics. In this condition the gross
weight was 13,234 pounds with a C.G. wheels up, of 29.63 percent M.A.C. Mixture auto-
rich; throttle wide open on all tests. Horsepower data obtained with torquemeter."

I was actually shooting for an earlier version without the water injection and 8 guns.[/QUOTE]


Good middle of war P-47 information seems hard to find, it is either from the B-47B & C when they were going into service and a lot of things were either marked "provisional" or estimates or just plain weird (same fuel burn with and without the 200 gallon ferry tank????) or it is for the P-47M &N with different engines and different turbos and different fuel tanks on the N.
Thanks for trying.

 

[CORSNING]

Dammit guys, I need to change the information in my post #134. I need
to substitute the water-injected P-47D-10's performance with the P-47D-6's.
That would make an even greate...........Ah crap, forget it. Someday I will
post it all somewhere. 'Till then have at it.

 

[Ivan1GFP]

This is a myth.
P38's loss of an engine would not survive any better.
The asymmetry of the remaining engine would flip over the aircraft.
A pilot would have to be lucky and have enough altitude to correct for this.

Another P38 Achilles Heal was combat damage to the rear Elevator.

Hello Dan Fahey,
The situation you describe would only be true at very low airspeeds and high power settings along with an instant loss of power: Below minimum control speed for single engine operation.
Above that speed, generally things are not so bad.

Combat damage to the "rear Elevator" for just about ANY aircraft would bring it down.

Hello Corsning,
Which are the faulty figures?
From AHT, the gross weight of an early P47D was 12,740 pounds and for a P-47D-23 would be 13,582 pounds.
From what I can find, the default ammunition load tended to vary a bit, but for the gross weights I just listed was 8 guns with 275 rounds per gun. Later models went down as low as 200 rounds per gun.

- Ivan.

 

[soulezoo]

This is a myth.
P38's loss of an engine would not survive any better.
The asymmetry of the remaining engine would flip over the aircraft.
A pilot would have to be lucky and have enough altitude to correct for this.

Another P38 Achilles Heal was combat damage to the rear Elevator.

This was back in the mid 80's and I saw Lefty Gardner shut down an engine at Reno and land safely in his P-38. I have no info on why he had to shut down the engine, but I witnessed this and he definitely did not flip over.

 

[CORSNING]

Ivan,
I apologize sir. I have run out of time tonight. This is family time now
and I have to be up at 3:50 a.m.
I was going to post (and should have to begin with) the P-47D-6-RE
No. 42-74616 report dated 28 September 1943.
It can be seen at www.wwiiaircraftperformance.org that was put together
by Mike Williams and Neil Stirling.

 

[DerAdlerIstGelandet]

This was back in the mid 80's and I saw Lefty Gardner shut down an engine at Reno and land safely in his P-38. I have no info on why he had to shut down the engine, but I witnessed this and he definitely did not flip over.

Any dual engined aircraft can fly on a single engine.

Engine Failure After TakeOff - Light Twin Engine Aircraft - SKYbrary Aviation Safety

 

[pbehn]

Any dual engined aircraft can fly on a single engine.

Engine Failure After TakeOff - Light Twin Engine Aircraft - SKYbrary Aviation Safety

I don't know about the P-38 but not all WW2 twins had complete redundancy on engines, so only had generators/compressors on one.

 

[DerAdlerIstGelandet]

I don't know about the P-38 but not all WW2 twins had complete redundancy on engines, so only had generators/compressors on one.

You still could fly it on a single engine...

 

[Shortround6]

Early P-38s only had one set of accessories (pumps, generator, etc) later ones got two generators but I am not sure about a full duplicate set of pumps. I believe P-38s used electric propellers, having the battery go dead means some pretty tricky work to adjust the pitch on props and you better get it right the first time.

 

[pbehn]

You still could fly it on a single engine...

As per S/Rs post, they could fly on one engine but not both engines could be that one engine.

 

[FLYBOYJ]

This is a myth.
P38's loss of an engine would not survive any better.
The asymmetry of the remaining engine would flip over the aircraft.
A pilot would have to be lucky and have enough altitude to correct for this.

Another P38 Achilles Heal was combat damage to the rear Elevator.

Dan - do you know that a CRITICAL ENGINE is? Do you know what ENGINE OUT PROCEDURES are? Go do some homework and come back because once again and as always you speak from deep bovine fecal cavities.

Oh - and do show us statistics about aircraft losses due to rear elevator damage during combat.

 

[FLYBOYJ]

Early P-38s only had one set of accessories (pumps, generator, etc) later ones got two generators but I am not sure about a full duplicate set of pumps. I believe P-38s used electric propellers, having the battery go dead means some pretty tricky work to adjust the pitch on props and you better get it right the first time.

As per S/Rs post, they could fly on one engine but not both engines could be that one engine.

The P-38 could easily fly on one engine (to include the early ones) and it did fly well. The P-38 did not have a CRITICAL engine so ENGINE OUT procedures were the same whether the left or right engine failed. Yes - early P-38s had the issue with one generator but in the end each engine had 2 magnetos which meant the aircraft kept flying. (DAN ARE YOU READING THIS)

The P-38 is one of the only twins I know of where you had to REDUCE power on the good engine if you had an engine failure during take off. (Wes, if you read this chime in on other GA or Corp twins with the same characteristics.)

"Another issue with the P-38 arose from its unique design feature of outwardly rotating counter-rotating propellers. Losing one of two engines in any twin engine non-centerline thrust aircraft on takeoff creates sudden drag, yawing the nose toward the dead engine and rolling the wingtip down on the side of the dead engine. Normal training in flying twin-engine aircraft when losing an engine on takeoff would be to push the remaining engine to full throttle; if a pilot did that in the P-38, regardless of which engine had failed, the resulting engine torque and p-factor force produced a sudden uncontrollable yawing roll and the aircraft would flip over and slam into the ground. Eventually, procedures were taught to allow a pilot to deal with the situation by reducing power on the running engine, feathering the prop on the dead engine, and then increasing power gradually until the aircraft was in stable flight. Single-engine takeoffs were possible, though not with a maximum combat load."

Lockheed P-38 Lightning Airplane Videos and Airplane Pictures

 

[FLYBOYJ]

Go to 30:01 in this clip. Actually the whole thing is quite entertaining!