P-38 performance numbers I found

[Captain Virgil Hilts]

I found some interesting P-38 performance numbers while doing so searching for replies to another thread. As I said in the other thread, part of this ,and maybe all of it, comes from an old thread in another online discussion group, and was posted by Widewing, under another name. I have talked to Warren Bodie, and he says this information is available to the public, in the USAF archives, and possibly at Lockheed Martin, if you want to do the research.

Take a look.

Time to height:
P-38F from sea level to 10,000 ft at 48 in. Hg. MAP, 2,900 rpm: 3.56 min.
P-38F from brake release to 10,000 ft.: 4 min, 35 sec.
P-38J sea level to 23,800 ft, 60 in. Hg. MAP, 3,000 rpm: 6.19 min., still
maintaining 2,900 fpm at that altitude.
P-38L sea level to 20,000 ft. 60 in. Hg. MAP, 3,000 rpm: 4.91min, still
maintaining 3,450 fpm at that altitude.

P-38G  345 mph @ 5,000 ft. / 402 mph @ 25,000 ft.(METO) / Climb: 2,885 fpm.avg.
P-38H  352 mph @ 5,000 ft. / 409 mph @ 22,000 ft.(METO) / Climb: 3,070 fpm.avg.
P-38J   360 mph @ 5,000 ft. / 421 mph @ 22,500 ft.(METO) / Climb: 3,585 fpm.avg.
P-38L   365 mph @ 5,000 ft. / 442 mph @ 22,500 ft. (WEP) / Climb: 3,750 fpm.avg.

Allison spent a great deal of time and money on the "dash thirty" program.
They produced volumes of dynometer data for Lockheed and the AAF.
Lockheed did their own testing and confirmed the Allison numbers. Hence,
the installation of the -30 in the L model.

The following are the CORRECT stats for the Allison V-1710F-30.

Ratings [minutes]          Power    RPM  Manifold [in.Hg]  Altitude [ft]
Normal (no limit)          1,100    2,600        44                 30,000
Take Off (5)               1,475    3,000        54                    SL
Military (15)              1,475    3,000        54                 30,000
WEP (5)                    1,725    3,000        60                 28,700

Max speed at sea level: 352 mph
Max speed at 5,500 ft : 369 mph
Max speed at 23,500 ft. 440 mph (WEP) 5 minutes max.
Max speed at critical alt: 444 mph @ 25,800 (WEP) 5 minutes max.

Max climb rate at sea level: 4,225 fpm (50% fuel, normal ammo)
Max climb rate at 23,400 ft: 3,940 fpm
Time to 23,400 ft: 5.94 minutes
Time to 30,000 ft: 8.86 minutes
Service Ceiling: 44,000 ft.


The most commonly printed max speed numbers for the P-38L state
414 mph. How interesting. Consider that the L was fitted with the -30
Allisons, as opposed to the -17 on the J. There is a big difference, and
I'll go into that a little later.

The typical numbers presented for the J are 421 mph IN WEP.
The typical numbers presented for the L are 414 mph IN METO.
This is one of the pitfalls of using commercially available data. It
usually isn't researched very well. The difference between METO and
WEP is 600 hp. The -30 produced a minimum of 1,725 hp in WEP.
As opposed to 1,425 hp in METO.

The -17 installed in the P-38J had the same METO rating as the -30
at 1,425 hp. However, the -17 only made 1,600 hp in WEP. The
additional power could push the L to speeds over 440 mph. Warren
Bodie concludes the maximum speed in WEP as 443 mph at altitudes
between 20,000 and 23,500 ft. Bodie obtained his data directly from
Lockheed, where he was employed as an engineer on the U-2 and
F-117 programs. Therefore, I tend to except Bodie as a more credible
source than Green and Swanborough et al.

[worr]

Originally posted by Captain Virgil Hilts



The following are the CORRECT stats for the Allison V-1710F-30.

Ratings [minutes]          Power    RPM  Manifold [in.Hg]  Altitude [ft]
Normal (no limit)          1,100    2,600        44                 30,000
Take Off (5)               1,475    3,000        54                    SL
Military (15)              1,475    3,000        54                 30,000
WEP (5)                    1,725    3,000        60                 28,700

Why is Bodie the only source on this reported 1725 HP at full boost? I've never been so frustrated as reading all reports being at 1,600 or lower.

Bodie is the Bible on the P-38. But there must have been numbers that were circulated before his book was published to have it so wrong.

Worr, out

[Captain Virgil Hilts]

I don't really know why that is, but Allison was spending massive amounts of money not only on that project, but also on the G series which was used in the P-82 twin Mustang. In fact, the G series hit 2000 horsepower without turbochargers, although it could not maintain that level at high altitudes. Had the G series been put into the P-38, and equipped with turbochargers, the P-38 would have had 2000 horsepower at altitudes in excess of 25,000 feet.

Bodie was an engineer for Lockheed, and had full access to all the records, and all the engineers and test pilots, including Kelly Johnson.


The Allison is a very under rated engine. I've worked on them, and I've compared them to the Merlin, and the Merlin simply just is not as good an engine.

[worr]

Originally posted by Captain Virgil Hilts
Bodie was an engineer for Lockheed, and had full access to all the records, and all the engineers and test pilots, including Kelly Johnson.  

But I think that's why the data hasn't made its way out.

Ever read what Piper Corporation used to put our for their cruise speeds. Nose pitched down, maybe.

I'd still like to see an outside source for these top speeds, and HP ratings, before it becomes mainstream. Unfortunately, that has yet to happen.

Worr, out

[gripen]

Well, this data has been under discussion several times here. So far no one has come out with actual data and there appears to be several versions of the F30 WEP ratings.  1725hp at 60" and 3000rpm is quite questionable because F17 did about 1600hp at same rpm and MAP.

gripen

[wells]

The Air Force never purchased any G model engines until after the war.  Sure, a P-38 was probably used as a testbed in it's development, but almost guaranteed no P-38 in service had that engine.  That 1725 hp figure was achieved at 3200 rpm, not 3000, unless 64" was used, which I've also seen reference to.  A good book to check out is "Vees for Victory".

[whgates3]

http://home.att.net/~ww2aviation/P-38-3.html by Carlo Kopp (an Austrailian), duscussing the P-38L says:

"The two Allison V-1710F-30 V-12s had a 5.5 in. bore and 6.0 in stroke, providing a compression ratio of 6.5. These drove Curtiss Electric constant speed props via a 2:1 reduction gear, delivering 1,475 HP military and takeoff ratings at 3,000 RPM, or 1,612 HP maximum rating at 3,000 RPM and 60 in. of manifold pressure. Some later engines are described as delivering up to 1,725 HP WEP rating. The engines required 100 octane or higher rated fuel, and had 13 USG oil capacity. The oil was cooled in two outboard chin core radiators, vented via automatically controlled flaps on either side of the nacelle. Fuel consumption was 0.65 lb/HP./hr at 1,100 HP normal rating, at 2,600 RPM"

here is a picture of Dr. Kopp


here he is in an F-18

whatta guy!

[Captain Virgil Hilts]

Originally posted by wells
The Air Force never purchased any G model engines until after the war.  Sure, a P-38 was probably used as a testbed in it's development, but almost guaranteed no P-38 in service had that engine.  That 1725 hp figure was achieved at 3200 rpm, not 3000, unless 64" was used, which I've also seen reference to.  A good book to check out is "Vees for Victory".

I never said that the G series was ever used in the P-38, I said it wasn't, but SHOULD have been. The G series had more than 1725 horsepower in WEP, and was not turbocharged, and all P-38 engine were turbocharged, except those which were built for export. It was the F-30, that had 1725 horsepower in WEP, at 3000 RPM, and 60" of manifold pressure, and it WAS installed in the P-38L-5-Lo.

[gripen]

Main differences between the F-17 and F-30 were crankshaft and carburator, there is no physical reason why the F-30 should perform different than the F-17 at same rpm and MAP. Allison rated the F-30 for 1725hp at 3200rpm (and at 60" according to "Aircraft engines of the World) and the manual of the P-38L claims that 1600hp at 3000rpm and 60". I wonder which source I should believe?

The problem with the P-38 is that lot of nonsense is written about it and people just want believe that nonsense.

gripen

[Captain Virgil Hilts]

Originally posted by gripen
Main differences between the F-17 and F-30 were crankshaft and carburator, there is no physical reason why the F-30 should perform different than the F-17 at same rpm and MAP. Allison rated the F-30 for 1725hp at 3200rpm (and at 60" according to "Aircraft engines of the World) and the manual of the P-38L claims that 1600hp at 3000rpm and 60". I wonder which source I should believe?

The problem with the P-38 is that lot of nonsense is written about it and people just want believe that nonsense.

gripen

As a race engine builder and mechanic, with some first hand Allison experience, I can tell you that even subtle and small changes in a carb can make a big difference. I recently changed carbs on a 406 and on my dyno, I picked up 50 horsepower on a baseline of 700 horsepower. The carb was the same brand, same model, with the same cfm rating, just a different guy modified it. Actually, changing the counterweights (what was done to the later model Allison cranks) will make a performance difference.

[gripen]

Well. I'm really interested to see (verifyable) data which supports your claim that 12-counterweight crankshaft alone will make a performance difference. Allison's own rating is quite clear; 1725hp at 3200rpm (not 3000rpm).

gripen

[senna]

The idear gripen sure sounds ok.

[gripen]

I'd really like to see hard data rather than (questionable) ideas. The source used by Virgil has claimed several different ratings for the F-30, currently there is 64" claimed in the site. Suprisingly critical altitudes for 60" and 64" are same? Who is right?

gripen