38Q for Widewing

[Tac]

Hello Widewing!


I was wondering if you had any charts for the P-38F


Notably their engine HP rating, their level accel vs alt ; climb rate and top speed.


Cant find much info on the F model . I used to think it was just an H with a slightly better engine and tweaks to some of its components.

[Widewing]

Originally posted by Tac
Hello Widewing!


I was wondering if you had any charts for the P-38F


Notably their engine HP rating, their level accel vs alt ; climb rate and top speed.


Cant find much info on the F model . I used to think it was just an H with a slightly better engine and tweaks to some of its components.

Hi Tac,

I suspect you are thinking of the XP-38K rather than the F model.

Lockheed took a P-38E and modified the airframe, installing V1710-F15 engines and revised the intercooler installation to that which appeared on the P-38J. In addition, they also installed new propellers, switching from the Curtiss-Wright electric props to "high activity" Hamilton Standard paddle blade props with a revised reduction gear ratio (due to an increase in prop diameter). This required a redesign to the engine cowling as the HS prop/F-15 combination had a higher thrust line. The V-1710-F15 engines had a MIL power rating of 1,450 hp.

Actual test data comes from internal Lockheed test reports and those resulting from tests of a second example built on a P-38J airframe, designated the P-38K-1-LO. Bodie mailed me a photocopy of climb and speeds charts. They are buried in my boxes of data. I will set aside some time and dig it out during the coming week. I do have a basic summary of the testing I will share here. Much of this was published in Bodie's P-38 book.

P-38K-1-LO as tested by the USAAF at Eglin Field:

Max speed at critical altitude: 432 mph at 29,600 ft
Max speed at 20,000 feet: 411 mph
Max speed at sea level: 352 mph
Initial rate of climb: 4,800 fpm
Time to 20,000 feet: 5.0 minutes
Service ceiling: 46,800 feet
Rate of acceleration: Based upon Dean's calculations, the P-38L should accelerate at 4.13 ft/sec/sec. Lockheed claimed that the HS props were 5% more efficient than the CW units. Therefore, expect a slight increase in acceleration of about 0.2 ft/sec/sec.

Compared to the typical P-38F:

Max speed at critcal altitude: 399 mph at 25,000 feet
Max speed at 20,000 feet: 385 mph
Max speed at sea level: 328 mph
Initial rate of climb: 3,120 fpm
Time to 20,000 feet: 8.9 minutes
Service ceiling: 39,200 feet
Calculated rate of acceleration: 2.30 ft/sec/sec (per Dean)

Naturally, adding speed and climb is important. However, the issue of compressibility was not addressed until the P-38J-25-LO, so the P-38K may not have arrived in service with the dive recovery flaps. Even with them, a maximum speed of 432 mph at nearly 30,000 feet would mean that the P-38K would be very close to its critical Mach in level flight (440 mph at 30k). So, even dropping the nose a few degrees would result in buffeting. Truly, a realistic combat ceiling for the P-38 (any model) was closer to 25,000 feet, with 20,000 feet being even more comfortable. This has been largely affirmed by actual combat and the post-war comments of P-38 pilots who felt that the P-38 was out of its element at 30k and above, but who swore that it was a marvelous machine at medium altitudes and below.

When I find the P-38K-1-LO chart, I'll scan it and post it.

My regards,

Widewing

[Ack-Ack]

If the K had been approved and mass produced and later incorperated the dive flaps, would it have been better than the L?



ack-ack

[Widewing]

Originally posted by Ack-Ack
If the K had been approved and mass produced and later incorperated the dive flaps, would it have been better than the L?



ack-ack

I imagine that had the war production board authorized the P-38K for production, there probably would not have been an L model. It's also likely that the production K would have used the up-rated V1710-F30 engines as did the L model. With paddle-blade props, I would expect better acceleration, climb and a bit better fuel economy (more efficient props).

Speed would be very similar, but we know that max speed depended upon whether the engines were rigged to factory rated power, or the AAF's derated power (1,725 hp Vs 1,600 hp).

We know that Lockheed tech reps provided crew chiefs with instructions on how to rig the F30s for full rated power. What we don't know is how common this field mod was. I know several instances where pilots insisted on the re-rigging. I also know of two cases where the pilots preferred the increased reliability of the lower power setting. Virtually all references are to the 15th AF in Italy with the exception of one reference to the 9th AF in the ETO.

So, the answer to your question is yes, the K should have offered better performance than the L. However, the differences would generally be seen in climb and acceleration.

My regards,

Widewing

[Blixen]

38K

[Raptor]

If that's the case, why was the K not approved?

[Widewing]

Originally posted by Raptor01
If that's the case, why was the K not approved?

It was not built because the War Production Board denied Lockheed's request to shut down production for 3 weeks while they retooled the production line and retrained assemblers. Good enough is good enough for the guys flying desks.

Meanwhile, planes that had already proven to be dogs, like the Fisher P-75 and Curtiss P-60 were allocated huge amounts of manpower and money. What the WPB didn't do until it no longer mattered was set up a second assembly line for the P-38. P-47s were built in two plants, as was the P-51. F4Us were assembled in three different factories (Vought, Goodyear and Brewster). Eventually, Vultee was contracted to build P-38s, but it took them almost two years to get underway and they produced barely two weeks worth of production before the war ended.

My regards,

Widewing

[Blixen]

i was reading they didnt produce it because
they fear they could not supply enough of the engs in time

[F4UDOA]

TAC,

I have the P-38F AFDU by our British friends which includes some interesting comparisons to other contemporary Aircraft (Especially the Spit IX). I will post it as well as the P-47B AFDU which has some P-38F Comparisons.

[Tac]

Thanks u 2.

I do mean the 38F . Im just curious in its performance vs the 109E and F. I can get the charts for the E and F from the AH plane info section but none on the 38F

[Angus]

F4UDOA: Will you post on this thread?
Very interesting stuff there M8!!!

[batdog]

TAC..you old dog. Good to see you. You in game any?

[GtoRA2]

Widewing
 Awsome stuff.


 Was it in one of Bodies books that he claimed the war production board was not so much concerned with getting the best planes but keeping the profits going to some companies?


Or am I remebering wrong.

[Widewing]

Originally posted by GtoRA2
Widewing
 Awsome stuff.


 Was it in one of Bodies books that he claimed the war production board was not so much concerned with getting the best planes but keeping the profits going to some companies?


Or am I remebering wrong.

Bodie correctly pointed out that the WPB was partly populated with officers of major corporations, such as General Motors. These gentlemen had obvious conflicts of interest that in retrospect cannot be overlooked. Captains of industry were on the board due to political connections, and also because they had the ability to facilitate changes quickly. In hindsight it becomes obvious that some decisions were based solely upon business and not the needs of the services.

However, much of Lockheed's problems were created by Lockheed. Failure to expedite P-38 development was Lockheed's doing. They preferred to push commerical designs in the two years prior to Pearl Harbor. They were also slow to address known weaknesses in the P-38 design. It wasn't until middle 1942 that Lockheed's management realigned corporate priorities and allocated the resources required to move P-38 development up to the same speed as Republic and North American. The only reason a fully developed P-38 (such as the L series) wasn't ready in 1943 was because Lockheed was simply slow. This had the effect of causing the WPB to doubt Lockheed's promises and directly influenced their decision not to build the P-38K, despite the fact that Lockheed had shown significant improvement in rapidly getting changes into production. Add to this; the WPB was extremely conservative, preferring an adequate design currently being produced at acceptable rates to a new design that may have delays and teething issues. Again, good enough was good enough from their vantage point. However, they were flying desks and not facing the cream of the Luftwaffe at 25,000 feet over Europe.

There were many boneheaded decisions made by the WPB, the Department of War and brass hats within the Army. How else could anyone explain why the P-40 was still in production well into 1944, or why front line USAAF units were still flying P-39s when P-63s were were being stockpiled for delivery to the Soviets? You can attribute the P-51 being rapidly produced to the demands of the combat commands and not the decision making ability of those in high places.

My regards,

Widewing