P-38 vs P-51

[P-39 Expert]

"Figures used were for a P-47 with drop tank at "ferry" climb. Doubt escort missions used "combat" climb figures. All figures comparable for both planes. "



But it is not how the figures were computed is it?

I would note also that the figures for the P-47 from that manual were preliminary, the manual even in updated form is from one month after the first P-47s arrive in England and the 200 gallon ferry tank cannot be used as described. It doesn't feed fuel properly at altitudes much above 12,000ft.

It is also a little suspect in that there are only two flight operation charts. One with the 200 gallon tank full and one that says it is for BOTH a clean aircraft or one with an empty 200 gallon tank attached.

I don't know about you but I think that cruise settings/speeds would be a bit different with and without the 200 gallon ferry tank even if it is empty.

View attachment 523119

I don't believe that 200gal ferry tank was used in combat. In fact, the Thunderbolt was flying combat missions out of England with the 8th AF without drop tanks between April 30 and July 30 in 1943. No attachment points or any provision at all for external fuel on the new main escort fighter of the 8th AF bombing Germany from England. Then in August they got one 75 gallon belly tank and after that 108 gallon belly tanks became available.

 

[Shortround6]

The 200 gallon tank was not used in "combat" but it was used operationally on some missions. They were partially filled and used for some of initial climb and forming up. The feed system due to tanks not being pressurized would not work at high altitudes. In a few cases squadrons fitted auxiliary fuel pumps that would work at higher altitudes but I don't believe the tanks were ever completely filled or carried to point were German aircraft were spotted.

 

[XBe02Drvr]

This conversation has gone well enough without a smartass comment...I would hope it continues that way.

It was a simple observation, not intended as a "smartass comment", and my apologies if it was seen as offensive.
Your perspective and mine here kind of echo the controversy that has thrived in the fighter community ever since the days of Bristol F2Bs and Fokker D7s: which is more valuable, an extra crewman, or an extra bag of fuel? My take on it is that properly trained as an integrated crew, the second crewman can backstop the pilot on situational awareness with regard to aft hemisphere traffic, checklists, altitude and airspeed callouts when the pilot is "eyes out", as in a bombing run or an ACM maneuver, etc. Back in my day, the Navy was losing single seaters to target fixation at twice the rate of the F4 and the A6 .
In any case, this whole 1 vs 2 crew digression is just a sideshow to the main topic, which IIRC, was the P38 training issues in its early days. I suggest that what happened was typical of what can happen when you introduce a twin into a hardcore single engine community. "It's just a bigger pursuit ship with two of everything. Otherwise, just another pursuit". NOT! For most FTU instructors it was their first twin, their first trigear, and their first turbo, and they couldn't even climb in the back seat and show Dilbert how it's done. I remember watching A7 initial training up at NAS Cecil, where all flights were solo, and instructors flew chase on their students in another A7 while coaching them around the bounce pattern. Close calls were the order of the day. The service life of the A7 was half over before the two seat trainer showed up.
Cheers,
Wes

 

[CORSNING]

Wes,
I am 76.5" tall and have just one question for you.
How the hell did you fit into the F-102 even semi-comfortably with gear on????

 

[XBe02Drvr]

Wes,
I am 76.5" tall and have just one question for you.
How the hell did you fit into the F-102????

I am 77" tall, and the answer is: scrunched up into a near fetal position. It was only a primitive analog flight simulator, no flight gear except a "poopie suit" over my street clothes, and I didn't have to strap into a G-tolerant, ejection-capable position, but getting my feet on the rudders, my legs under the panel, and around the scope was an exercise in contortion.
Cheers,
Wes

 

[CORSNING]

No $h!+!!!!!!!!!!!!!!!!! You had mentioned your height once before.
I was just curious of the magic that you used to accomplish that feat.
I salute your magnificent efforts.

I am not a fighter pilot. Good thing because I couldn't stand the
crampness of most cockpits. Although I liked the looks of the P-47's.
In there you always had a choice if being shot at I remember reading.
1. Hunch down and let the tank like armor of the seat take the punishment.
2. Get up and run around the cabin dodging bullets.

 

[P-39 Expert]

Are we seriously trying to compare a P-39 with a P-47?

...even if it is in an off way?

Just making an example of the Thunderbolt's short range.

So the P-39 models contemporary to the P-47 weren't comparable?

 

[CORSNING]

Just making an example of the Thunderbolt's short range.

So the P-39 models contemporary to the P-47 weren't comparable?

Not as a bomber escort at 20,000 ft.


Please give me a little time now and I will put a side-by-side performance comparison together.

 

[Shortround6]

So the P-39 models contemporary to the P-47 weren't comparable?

Only if you believe the P-39 could get 3 1/2 times the gas mileage of a P-47.

It will get a lot more miles per gallon but not 3 1/3 times (87 gallons vs 305) so the P-47, short legged as it is, still beats the P-39.

Then you add drop tanks, 75 gallons for the P-39 but the added drag is high and performance takes a real hit.

Adding 75 gallons to a P-47 doesn't change the total fuel all that much but since the P-47 is so much bigger the addition of a single drop tank (unless really poor design) doesn't change the total drag by as big a percentage as adding a drop tank to the P-39. P-39 is catching up but doesn't make it.

The P-47 can cruise at the desired altitude and speed with one or more drop tanks attached.
The P-39 cannot.

 

[DerAdlerIstGelandet]

This conversation has gone well enough without a smartass comment...I would hope it continues that way.

My great Uncle flew the P-38 in the PTO and I was taught to fly (yes, fly) by family friends who were: USAAF, USMC, Luftwaffe and USN combat pilots.

So allow me to rise out of my armchair and suggest you and Ivan go back to the first several posts of this thread and get up to speed about the conversation.

And while we're on the subject of "crew-served" twins. Please explain in detail how the RO/Gunner assisted the pilot in his operations, again?
Did the RO reach over and switch the fuel selectors? Did the RO lean down and adjust the fuel-mixture?
And how did the "crew-served" Defiant fare...did the gunner climb out of the turret and help the pilot at some point?
Being an extra pair of eyes to the rear was one thing, but that's not alot of help up in the office when things are getting hairy.

In multiple crew ("crew served") aircraft any extra set of eyes, or ability to assist in non flying duties is extremely helpful.

1. The eyes to the rear, are not glued to the rear. I assure you (from experience) that all heads on board, are on a swivel, and scanning, especially when the shit hits the fan.

Direct communication from these non flying crew members can directly influence and impact decisions made by the pilot on the controls.

2. Being able to assist in non flying tasks such as radio calls, navigation, fuel checks, checklists, etc., all relieves the pilot on the controls of those tasks, freeing up his attention, and reducing stress levels.

Don't underestimate the "non rated" or "non flying" crew members, and their ability to influence, and assist in the operation of an aircraft. It is an essential part of what we call CRM today. One of the most important aspects of it is 1+1>2, and that despite the PIC having all final say over everything, crew members communicate and act as a team.

 

[P-39 Expert]

Only if you believe the P-39 could get 3 1/2 times the gas mileage of a P-47.

It will get a lot more miles per gallon but not 3 1/3 times (87 gallons vs 305) so the P-47, short legged as it is, still beats the P-39.

Then you add drop tanks, 75 gallons for the P-39 but the added drag is high and performance takes a real hit.

Adding 75 gallons to a P-47 doesn't change the total fuel all that much but since the P-47 is so much bigger the addition of a single drop tank (unless really poor design) doesn't change the total drag by as big a percentage as adding a drop tank to the P-39. P-39 is catching up but doesn't make it.

The P-47 can cruise at the desired altitude and speed with one or more drop tanks attached.
The P-39 cannot.

We computed the escort range out of the pilot's manual for both. We figured the combat radius with your formula for both. The P-47 even at a lower cruise power setting than normal HP has extremely short range even with a 110gal drop tank.

The P-39 would cruise with a drop tank at 25000' and would outclimb the P-47 even at that altitude. Why couldn't it escort bombers?

And please stop with the 87 gallons. It held 120gal internal and would hold more internal if the peashooter wing guns were removed.

 

[tomo pauk]

We computed the escort range out of the pilot's manual for both. We figured the combat radius with your formula for both. The P-47 even at a lower cruise power setting than normal HP has extremely short range even with a 110gal drop tank.

The P-39 would cruise with a drop tank at 25000' and would outclimb the P-47 even at that altitude. Why couldn't it escort bombers?
...

Because it didn't have the combination of range (as required by geography and abilities of the A/C) and escort speed (as required by end user, that was based on realities of ETO as predominant war theater for that user). End user specified 210 mpg IAS at 25000 ft (~ 310 mph TAS) cruise - the P-39Q (I don't have data for P-39N) with 75 gal tank cruised at 25000 ft at 267 mph TAS using 62 gph (@2600 rpm) = disqualified by end user due to not fulfilling a requirement.

The 'extremely short range' of P-47 didn't prevented it's use as escort, even if it was some 375 miles of radius. This is before we start talking about the bubble-top P-47s with 370+300 gals of fuel = 600 mile radius per USAF, 800 miles per RAF: link.

edited for typos

 

[Ivan1GFP]

And while we're on the subject of "crew-served" twins. Please explain in detail how the RO/Gunner assisted the pilot in his operations, again?
Did the RO reach over and switch the fuel selectors? Did the RO lean down and adjust the fuel-mixture?
And how did the "crew-served" Defiant fare...did the gunner climb out of the turret and help the pilot at some point?
Being an extra pair of eyes to the rear was one thing, but that's not alot of help up in the office when things are getting hairy.

Hello GrauGeist,
I believe we have explained how additional crew members assist in the operation of the aircraft as a weapons system but for some reason you keep getting hung up on just flying the aeroplane.
As XBe02Drvr mentioned, having a rear gunner or WSO to keep an enemy in the rear hemisphere in sight even if they are not an immediate threat offload the pilot and increases situational awareness. The pilot can engage one threat while the WSO watches for others.

Your example of the Boulton-Paul Defiant is a great illustration of how splitting the workload can be beneficial.
In a defensive situation, especially at low altitude, the probably should know approximately where an attacker is, but doesn't need to keep the enemy in sight. The pilot can fly closer to the ground or other obstacles to try to shake the pursuer. The gunner doesn't' need to keep an eye out to avoid collision with terrain and concentrate completely on putting bullets into the enemy.

- Ivan.

 

[CORSNING]

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)

 

[Shortround6]

We computed the escort range out of the pilot's manual for both. We figured the combat radius with your formula for both. The P-47 even at a lower cruise power setting than normal HP has extremely short range even with a 110gal drop tank.

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.

The P-39 would cruise with a drop tank at 25000' and would outclimb the P-47 even at that altitude. Why couldn't it escort bombers?

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.

And please stop with the 87 gallons. It held 120gal internal and would hold more internal if the peashooter wing guns were removed.

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.

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?

 

[FLYBOYJ]

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

 

[XBe02Drvr]

I am not a fighter pilot. Good thing because I couldn't stand the crampness of most cockpits.

There's nothing wrong with a tight fitting cockpit as long as all the variables such as seat, armrests, headrest, rudder pedals, etc, have the necessary range of adjustment to fit your proportions, and the canopy rails don't chafe your shoulders.
In fact if you plan to chase the shouting wind along and hurl your eager craft through footless halls of air, you want to wear that eager craft like a parachute harness cinched up tight. Relative motion between you and your mount is a bad idea. You're not sitting in it and driving it; is an extension of your body and your nervous system. You are its brain and it is your body as you dance the sunsplit sky on laughter silvered wings.
A compact ergonomically laid out cockpit allows you to reach everything without unlocking your inertia reel, and feels comfortable like an old, but warm pair of long johns.
Cheers,
Wes

 

[XBe02Drvr]

Don't underestimate the "non rated" or "non flying" crew members, and their ability to influence, and assist in the operation of an aircraft. It is an essential part of what we call CRM today. One of the most important aspects of it is 1+1>2, and that despite the PIC having all final say over everything, but crew members communicate and act as a team.

Chris, sometimes you run into a pilot with a hardcore "single engine, single seat" mentality who just isn't convincible, and you have to agree to disagree. I met a few of them in the Nav. They didn't last long in the F4 community. Fortunately there were still a few F8 squadrons around.
Each time I went up in the jet, I was expected to participate in running the checklists, even though I didn't know where half the back seat circuit breakers were. They take the teamwork thing seriously.
Cheers,
Wes

 

[wuzak]

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

Yes, I think that will be a good thread. Right up thee with the P-40F vs Typhoon thread.

 

[XBe02Drvr]

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

Do you think minds will be changed or new truths revealed? Feels like deja vu.