How good (or bad) was the P-38, really? (1 Viewer)

[Shortround6]

Not sure about fuel pumps, you did need electric power to adjust props. Pilot may have had enough battery to feather the prop on the dead engine and go to cruise pitch, radio's suck power. Some pilots flying on battery turned off cockpit lighting and shut off radio intermittently.

 

[FLYBOYJ]

Not sure about fuel pumps, you did need electric power to adjust props. Pilot may have had enough battery to feather the prop on the dead engine and go to cruise pitch, radio's suck power. Some pilots flying on battery turned off cockpit lighting and shut off radio intermittently.

The boost pumps were normally used during take off and landing IIRC, the "normal" fuel pumps were engine driven again IIRC

 

[XBe02Drvr]

Some hydromatic props with counterweights will definitely go "flat" with pressure loss

It's all semantics, but I was taught that what you're describing above is called a "single acting hydraulic counterweight" propeller, whereas "Hydromatic" is a UA trademark applying exclusively to double acting hydraulic props of their manufacture. According to my instructor, MR. Hamm, in the late 30s and early 40s, United Aircraft guarded their patent jealously (Wright Brothers style) and tried to corner the worldwide market for double acting hydraulic propellers, exhorbitantly charging for access to them and leaving the market wide open to undercutting by Curtiss Electric. You don't think ol' Hambone might have been a little prejudiced, do you? He sure seemed to have had it in for Curtiss. He came to the school from the prop shop at defunct Mohawk Airlines, which was all Hydromatic.

 

[FLYBOYJ]

It's all semantics, but I was taught that what you're describing above is called a "single acting hydraulic counterweight" propeller, whereas "Hydromatic" is a UA trademark applying exclusively to double acting hydraulic props of their manufacture. According to my instructor, MR. Hamm, in the late 30s and early 40s, United Aircraft guarded their patent jealously (Wright Brothers style) and tried to corner the worldwide market for double acting hydraulic propellers, exhorbitantly charging for access to them and leaving the market wide open to undercutting by Curtiss Electric. You don't think ol' Hambone might have been a little prejudiced, do you? He sure seemed to have had it in for Curtiss. He came to the school from the prop shop at defunct Mohawk Airlines, which was all Hydromatic.

Kind of funny - over 40 years ago I now remember a teacher saying the same thing about UA

 

[warbird51]

Bullseye! I can't find the story at the moment but that's the issue, he couldn't control his electric

It's all semantics, but I was taught that what you're describing above is called a "single acting hydraulic counterweight" propeller, whereas "Hydromatic" is a UA trademark applying exclusively to double acting hydraulic props of their manufacture. According to my instructor, MR. Hamm, in the late 30s and early 40s, United Aircraft guarded their patent jealously (Wright Brothers style) and tried to corner the worldwide market for double acting hydraulic propellers, exhorbitantly charging for access to them and leaving the market wide open to undercutting by Curtiss Electric. You don't think ol' Hambone might have been a little prejudiced, do you? He sure seemed to have had it in for Curtiss. He came to the school from the prop shop at defunct Mohawk Airlines, which was all Hydromatic.

If the Curtiss Electric propeller loses electrical power, the prop will stay in the pitch setting it was when the power failed. It will not change pitch.

 

[FLYBOYJ]

If the Curtiss Electric propeller loses electrical power, the prop will stay in the pitch setting it was when the power failed. It will not change pitch.

Thanks for the clarification, I'll stand to be corrected. I went through several old text books and manuals and couldn't find this, do you have a reference?

 

[warbird51]

Thanks for the clarification, I'll stand to be corrected. I went through several old text books and manuals and couldn't find this, do you have a reference?

I have worked on P-40's and was crew chief on a FM2 Wildcat with Curtiss Electric props. The manuals went with the Wildcat when the owner sold it 3 years ago

 

[Peter Gunn]

If the Curtiss Electric propeller loses electrical power, the prop will stay in the pitch setting it was when the power failed. It will not change pitch.

I'll take your words as fact no problem, it remains that he blamed the generator failing for the loss of the aircraft and I thought I remembered it as the prop controls.

What else could it have caused for him to have to bale? Really wish I could hunt down the story, it was on one of those old first gen type websites with lot's of text.

 

[Greg Boeser]

Explain then the rash of runaway propellers experienced by the Martin B-26? The official explanation was that low battery power caused the prop controls to malfunction.
One pilot offered up a counter explanation, suggesting that the prop controls somehow got shorted when the throttle was firewalled. He survived such an overspeed on takeoff by easing the throttles back until proper prop response returned.

 

[FLYBOYJ]

Explain then the rash of runaway propellers experienced by the Martin B-26? The official explanation was that low battery power caused the prop controls to malfunction.
One pilot offered up a counter explanation, suggesting that the prop controls somehow got shorted when the throttle was firewalled. He survived such an overspeed on takeoff by easing the throttles back until proper prop response returned.

That's why I'm remembering for some reason these electric props going into flat pitch during a power failure but it would make more sense for the propeller to remain at the last setting prior to electrical failure (as mentioned by Warbird51)

 

[warbird51]

Explain then the rash of runaway propellers experienced by the Martin B-26? The official explanation was that low battery power caused the prop controls to malfunction.
One pilot offered up a counter explanation, suggesting that the prop controls somehow got shorted when the throttle was firewalled. He survived such an overspeed on takeoff by easing the throttles back until proper prop response returned.

If there is a

Explain then the rash of runaway propellers experienced by the Martin B-26? The official explanation was that low battery power caused the prop controls to malfunction.
One pilot offered up a counter explanation, suggesting that the prop controls somehow got shorted when the throttle was firewalled. He survived such an overspeed on takeoff by easing the throttles back until proper prop response returned.

I was referring to loss of electrical power. If you have a short in the circuit then the short can cause the prop to move in either direction. Heck we washed the Wildcat once and water got into the contacts where the motor mates to the hub and when we started the engine to dry the engine off, the prop moved to high pitch (low rpm). Dried off the contacts, prop worked fine

 

[XBe02Drvr]

Explain then the rash of runaway propellers experienced by the Martin B-26? The official explanation was that low battery power caused the prop controls to malfunction.

Think about how a constant speed propeller behaves when it's working properly. Ready for takeoff, brakes set, throttles coming up, prop (at full increase) is on its low pitch stops. As RPM approaches redline, governor increases pitch slightly to provide enough rotational drag to stop the RPM rise at redline.
Now, cleared for takeoff, brakes released, plane rolls forward, and with increasing forward relative wind, rotational drag decreases slightly and engine torque tries to spin the prop faster. How do you suppose the governor prevents this? You got it, it increases prop pitch to increase rotational drag back to the value that matches engine torque. As aircraft accelerates and forward relative wind increases, prop pitch has to keep increasing to keep RPM in check.
Now what happens if the prop stops responding to the governor as the aircraft accelerates through forty knots? Once again, you got it. Runaway! The faster the aircraft goes the faster the engine will spin. The only way to prevent engine disintegration is to reduce throttle, which quite likely will not support flight.
Another possible scenario, not related to electrical failure, is failure of a slipring or brush that transfers electrical power to the prop from the engine. If the "increase pitch" contact fails, the prop can only move in the "decrease pitch" direction, meaning that the constant "increase"-"decrease" commands that go on all the time become a ratcheting "decrease"-"decrease" series of responses, allowing engine torque to overwhelm propeller rotational drag and run wild.
Hope this has helped.

 

[SaparotRob]

It helped me.

 

[pbehn]

D denny some good info on this thread.

 

[IdahoRenegade]

My understanding is that the engines had trouble with the high cold air in ETO, whereas in SWPac, with fights lower in the atmosphere, the issue wasn't nearly so problematic. Mach issues were reduced as a result.

The plane itself, as noted above, was a burner and not a turner (at least until the flaps were added to later models). BnZ worked well against Japanese planes and doctrine, not so much against LW planes and doctrine. Hard to dive out of trouble against LW bounces.

It's one of my favorite WWII airplanes precisely because it was so outré. It's both beautiful and ridiculous in appearance, but was formidably fast, formidably armed, and just plain weird.

In Europe, much of the engine problems came from poor training/operation, as directed by early "on-site" commanders, the opposite of the direction of Lockheed and Allision. Specifically operating the engines at low-boost and high-rpm in cruise conditions. This does a couple of things-both bad. First, by virtue of being in low-boost, you aren't seeing much compression heating of the intake air. This means the engines are ingesting very cold air (50 below zero IIRC at upwards of 30k feet). The high-rpm condition means that you are sucking in LOTS of super-cold air. Both lead to a cold engine, cold, very thick, viscous oil that doesn't circulate properly, leading to engine failures. These same issues also lead to a cold intake manifold track, increasing the problem of fuel droplets dropping out of the intake mixture and condensing on the intake manifold. Think of taking your car, throwing it in 1st gear, and driving down the highway on a really, really cold winter morning.

"until flaps were added on later models". I think you mean boosted ailerons, which came about on the J-25-LO and all L models. These gave the P-38 one of the highest (perhaps the highest) roll rates of any WWII fighter AT HIGH SPEEDS (350mph or above). Without boost, most ailerons could not be fully deflected at high speed by the pilot. Now, you might be talking about the dive recovery flaps-these did not help turn rate from what I understand, but rather shifted the center of lift allowing for recovery from a "compressibility dive". The "standard" fowler flaps also had a "maneuver" setting on most models (IIRC starting with the F, someone correct me if I'm wrong). The flaps could be partially extended for extra lift and a tighter turn radius. I might be wrong about this, but I think the '38 actually had one of the tightest turning radii of allied or European fighters of the war (again, correct me if wrong). Where it lacked was a slow initial roll rate (lots of moment of inertia in the roll axis). But in pitch, it was always very good, from what I've read, and in a sustained turn.

Part of the problem in the ETO was that the '38 was introduced there in late-ish '43. Well, actually it was introduced in early-mid '42, then every one was shipped to N. Africa, leaving none in the ETO. It was then thrown into the long-range escort mission very shortly thereafter. With raw pilots with little training or experience. Add to that, we had a crapload of '47s (let alone Spits) available, but few '38s-and once past the range of the others-the ONLY plane in the fight was the '38. Meaning that, early on anyway, they often fought heavily outnumbered. With inexperienced pilots. Bad operating doctrine (tied to close escort with the bombers). Improper engine operating doctrine as mentioned above. With ground crews with limited experience with the type. And with questionable commanders. In comparison, the '47 was introduced much more gradually, with far more time for pilots to gain experience, and against a far less prepared, defended Europe. And in much higher numbers.

Not to say the aircraft didn't have some deficiencies (what aircraft didn't?). The "mach limit" (compressibility) issue was identified early (like 1940-41 time frame). Johnson and others at Lockheed begged to get the plane into a high-speed wind tunnel to identify the problem and formulate a solution. But the operators of those tunnels were supposedly afraid of breaking them...after a long delay it took an order from Hap Arnold to make it happen. But by then orders were flowing in, the plane was badly needed (remember, until December of '43, it was our ONLY long range, high performance, high altitude fighter) and there was resistance to making design changes and delaying deliveries. IMO one of the biggest mistakes of the war was not setting up other plants to build the '38. That would have made cutting in design changes much easier.

 

[P-39 Expert]

The P-38 had lots of problems, but it did have range. The P-47 had fewer problems, but not much range. Neither plane was the solution.

 

[Geoffrey Sinclair]

To note the P-38 cockpit heating was a problem.

Is there any information the P-38 consistently fought heavily outnumbered in the late 1943/early 1944 period, since that would mean a significant percentage towards a majority of the Luftwaffe's fighter sorties were consistently hitting the P-38 formations instead of the bombers or other fighters. Interceptors including the twin engined Me410 etc. which were part of the force in the time period. Luftflotte Reich held 814 single and 198 twin engined day fighters in late May 1944, numbers that had been largely going up since 1943 even as pilot quality went down.

P-38 strength in 8th Air Force Fighter Groups, various dates in 1944.

4-Jan-44 124
11-Jan-44 130
17-Jan-44 164
25-Jan-44 212
1-Feb-44 239
8-Feb-44 180
15-Feb-44 129
29-Feb-44 170
6-Mar-44 229
14-Mar-44 268
21-Mar-44 258
28-Mar-44 262
4-Apr-44 276
11-Apr-44 269
18-Apr-44 257
25-Apr-44 256
2-May-44 255
9-May-44 245
16-May-44 283
30-May-44 276
6-Jun-44 288
13-Jun-44 318
20-Jun-44 302
27-Jun-44 290
4-Jul-44 283
11-Jul-44 269
18-Jul-44 237
1-Aug-44 109
8-Aug-44 85
15-Aug-44 77
22-Aug-44 74
12-Sep-44 50
19-Sep-44 50
10-Oct-44 21
25-Oct-44 5
7-Nov-44 1

Using Joe Baugher's web site, data is model, first month of series production.

J-1 Jan-43 (3 built then, the other 7 in June)
J-5 Aug-43 (restart of J production)
J-10 Oct-43
J-15 Dec-43 (wing leading edge fuel tanks as standard)
J-20 May-44
J-25 Jun-44 (last 210 J production, dive flaps, boosted ailerons)
L-1 Jun-44
L-5 Oct-44 (final L block number)

The US fighter evaluation in 1944, turning, best was the FM-2 at 100 units, the P-51D-15 was 5th at 179, the P-38L 205, the P-47D-30 206. 1G, no flaps.

Quote,

The -25 mainly fixed Lockheed's flight control issues. Allegedly the intake problem overstressed Allison's small engineering team. The behavior of liquid / gas mixtures under extreme conditions is the core of "rocket science" and it was very rare knowledge back then, before computers enabled Computational Fluid Dynamics.

The P-38 Lightning

"To be more specific, the foremost problem was the temperature of the compressed air from the turbosupercharger entering the carburetor. High carburetor air temperature (CAT for short) can cause all kinds of engine problems including detonation, which can lead to catastrophic engine failure. Allison recommended a CAT of no more than 45 degrees C."

"As it turned out high CAT was one of the major problems limiting P-38 performance through the P-38H. The root cause was, of course, the limited cooling ability of the wing leading edge intercoolers found in all early P-38s. They were a very clever design, inducing almost no aerodynamic drag, but they were designed for the 1000 hp Allisons of the late 1930s. By 1943 Military power was up to 1425 bhp and War Emergency Power was 1600 bhp. The increased power required higher induction pressure, which through compression by the superchargers heated the air by several hundred degrees. There is no way that the simple intercoolers could keep CAT below 45 degrees C. when operating at high power at altitude."

CAT wasn't the only problem though. The centrifuge effect of the compressor and the temperature variations in the plumbing could separate out the heavier octane enhancing additives and worsen the destructive detonation. The scientists who really understood this stuff were elsewhere separating Uranium.

The planes performed better in the warmer Med and Pacific so that's where they went. Doolittle and Spaatz made the decision to use the available and very suitable Mustang instead of waiting past D-Day for large numbers of a better P-38 in a paper that I haven't been able to find online. This gives an excerpt:

http://www.amazon.com/forum/military%20history?cdForum=Fx5TS2W4P5EMS6&cdPage=2&cdSort=oldest&cdThread=TxZW9V919NXLHM

" A lot of this had to do with its poor intake manifold design, something that Gen. Jimmy Doolittle, who had a PhD in aviation science from MIT, pointed out in a report on the P-38's problems, written to Carl Spaatz in the spring of 1944."

"Doolittle specifically singled out the intake system of the V-1710 as a problem - the tetraethyl lead was somehow separating out with the uneven distribution which caused repeated problems with detonation in certain cylinders in the V-1710s (i.e., they would blow up and catch fire in flight - kinda nasty for the pilots, eh?)."

***"Doolittle's letter to Spaatz is about as clear cut of an explanation of the problems of the V-1710 - turbosupercharger combo at high altitude in Europe as any I've ever found. It's the smoking gun that answers the question of why the P-38 was pulled from almost all combat duty in Europe, remaining only as a photo-reconnaissance plane."***

The dive brake modification shows how long it could take to field a fix on that plane.

Fred Colvin's writing on war production illuminates the difficulty of finding the proper curvature for efficient turbocharger and jet engine compressor blades. Unable to calculate it, the scientists were demanding that the shop produce a variety of exotic and difficult-to-machine mathematical spirals to determine by experiment what was best.

http://people.math.umass.edu/~tevelev/475_2014/beittel.pdf

"However the Archimedean spiral is used in a variety of applications. One such interesting application is in scroll compressors."

End quote

Early 8th AF escort operations,

P-38 operations with the 8th AF started on 15 October 1943. The P-51 started escort operations in December 1943.

First escort mission, 20 October, 39 P-38, no kill claims, 321 P-47, 6 kill claims. No USAAF fighters MIA.

table is date / number of P-38 / P-38 kill claims / P-38 MIA // number of P-47 / number of P-47 kill claims / P-47 MIA. Bomber escort missions only

3 November / 45 / 3 / 0 // 333 / 11 / 2
5 November / 47 / 5 / 0 // 336 / 13 / 4
7 November / 0 / 0 / 0 // 283 / 1 / 0
11 November / 59 / 0 / 0 // 342 / 8 / 2
13 November / 45 / 7 / 7 // 345 / 3 / 3
19 November / 0 / 0 /0 // 288 / 0 / 0
26 November / 28 / 0 / 0 // 353 / 36 / 4
29 November / 38 / 2 / 7 // 314 / 13 / 9
30 November / 20 / 0 / 1 // 327 / 0 / 5
1 December / 42 / 0 / 5 // 374 / 20 / 2

The third set of figures is for P-51

5 December / 34 / 0 / 0 // 266 / 0 / 1 // 36 / 0 / 0
11 December / 31 / 0 / 0 // 313 / 20 / 3 // 44 / 0 / 1
13 December / 31 / 1 / 0 // 322 / 0 / 1 // 41 / 0 / 1
16 December / 31 / 0 / 0 // 131 / 1 / 1 // 39 / 1 / 0
20 December / 26 / 0 / 0 // 418 / 16 / 2 // 47 / 3 / 4
22 December / 40 / 0 / 2 // 448 / 9 / 2 // 28 / 6 / 0
24 December / 40 / 0 / 0 // 459 / 0 / 0 // 42 / 0 / 0
30 December / 79 / 0 / 0 // 463 / 8 / 11 // 41 / 0 / 2
31 December / 74 / 3 / 1 // 441 / 4 / 2 // 33 / 2 / 1

Totals, P-38 749 sorties, 21 kill claims, 23 MIA, P-47 6,877 sorties, 169 kill claims, 54 MIA, P-51 351 sorties, 12 kill claims, 9 MIA.

The first 8th Air Force mission using P-38J models of any type seems to have been on 28 December 1943. The 8th AF loss lists note H-5 losses to November 1943 to early January 1944, J-5 losses early January to September 1944, J-10 losses early January to June, J-15 mid April to September. No J-25. The ETO first P-38 group to have J-25 or L model was the 479th in August 1944, they were given 2 and found the dive flap system unreliable and so had the aircraft replaced with non dive flapped models. In October 1943 the USAAF in Britain had 105 P-38 and 159 P-51, in November it was 188 to 231, in December 380 to 266. In January 1944 it was 637 P-38 to 543 P-51, in February 669 to 699 and the P-51 stayed ahead for the rest of the war. These figures includes reserves

The following time line is 1943 to 1944, mainly from Air War Europa by Eric Hammel.

20th December The first freelance fighter mission is flown when the bombers turn up 30 minutes late and the 55th fighter group "puts into action a plan much discussed by fighter pilots - ranging ahead of the bombers as they converge on the bomber path. The 55th fighter group scores no victories on this day, but its new tactic gets the attention of VIII fighter command and there ensures a healthy debate that, in the end, will free the fighters from the outmoded close-escort doctrine of the day." Window is first used on this day as well. Some 491 fighters were used as escorts for 546 bombers, 12 of which were pathfinders.

6th January Doolittle gained command

7th January Phased escort tactics used, fighters fly to rendezvous points to relieve other fighters rather than a formation of fighters stays with a formation of bombers for the entire mission, 571 fighters for 502 bombers.

11th January the first officially sanctioned test of freelance fighter tactics, where fighter formations range ahead and to the side of the bomber formation hoping to catch Luftwaffe fighters as they are forming up, 592 fighters for 663 bombers. The USAAF mounts 2 raids that day, the one with the freelance experiment, to Oschersleben and Halberstadt, has the Oschersleben bomber formation hit hard by fighters and flak, losing 34 from 177 bombers despatched, the Halberstadt formation loses 8 from 114 despatched. The 221 escorting fighters for these two formations claim 29 kills for 3 fighters lost, 11 of the kills by the freelance fighters. Only the 56th fighter group freelances, with two formations of 36 and 48 fighters respectively. All the bombers were B-17s.

The second raid that day, to Brunswick, was largely reduced to targets of opportunity and lost 16 B-17s and 2 B-24s.

Of the 58 to 62 B-17s lost that day (sources vary again), including write offs, some 44 were lost to enemy fighters, 8 to flak, 2 to "battle damage" and 5 "operational" losses, according to my counts.

So the initial experiment would have a mixed report, the freelance fighters did above average but the bombers were clearly exposed to significant fighter attack.

21st January 56th fighter group turn in the first strafing kill claims, it is not until late March that strafing becomes a significant source of kill claims. In April according to the USAAF statistical digest fighters will lodge 418 kills in the air and 527 on the ground, versus 469 in the air and 76 on the ground in March.

24th January the first attempt at having fighters patrol an area for a time, not stick with a particular bomber formation, abandoned due to weather problems.

Ignoring 1942, when the first 8th Air Force P-38 group flew its first mission mid October 1943, there were 7 P-47 groups flying missions. The second P-38 group flew it first mission at the end of December. The third group flew its first mission in early March 1944, by which stage the 8th had 2 operational P-51 groups and was borrowing the 9th AF ones. In late May it was 4 P-38 to 7 P-51, by end July it was 1 P-38 to 10 P-51 groups flying missions.

8th AF P-38 units,
The 20th FG claimed 76 kills November 1943 to June 1944,
the 55th FG claimed 79 kills November 1943 to June 1944,
the 364th 35.5 kills March to June 1944,
the 479th 70 kills June to October 1944.

So around 260 kill claims. USAAF ETO fighters made 2,706 kill claims November 1943 to June 1944.

In terms of failed to return the 8th lost something like 257 P-38 November 1943 to October 1944.

Using the USAAF unit history and the USAAF kill claims lists I make the P-38 groups in the ETO as

20th sent 8/43 1st kill claims 11/43 converted to P-51 7/44 scored 90 out of wartime total of 209.5 kill claims in P-38s.
55th sent 8/43, 1st kill 11/43 P-51 7/44 106 of 303.5 kills in P-38s.
364th sent 1/44 1st kill 3/44 P-51 7/44 35.5 of 263 kills in P-38s.
367th sent 3/44 1st kill 6/44 P-51 3/45 74 of 85 kills in P-38s
370th sent 1/44 1st kill 5/44 P-51 2/45 37 of 38 kills in P-38s
474th sent 2/44 1st kill 7/44, 95 kill claims, only ETO P-38 group in May 1945.
479th sent 4/44 1st kill 6/44 P-51 11/44 75 of 154 kills in P-38s.

Note the kill claim breakdowns are based on everything up to and including the month of conversion counted as P-38 kills. Of the 7 groups 4 scored more kills after conversion to P-51. The P-38 arrived in the 8th Air Force around 7 weeks before the P-51 (or 9 bomber escort missions) and like the early P-51 had less internal fuel than later models. While until the second P-38 group flew combat at the end of the month there were more P-51 on escort than P-38 in December.

The 8th Air Force P-38 immediately hit a series of mechanical problems that had not been obvious in other theatres, the combat performance was also a problem. Even so as can be seen the P-38 strength in the 8th Air Force stayed high until July 1944. It was 2 groups at the end of 1943, 3 in early March 1944, 4 end May 1944, down to 1 by end July, to zero mid September, all moving to the P-51. Meantime it should be noted the 8th transitioned some P-47 groups earlier, it had 9 P-47 groups end January 1944, and that was down to 4 by mid May, 3 more P-47 groups converted in the final quarter of 1944. So it was not a case of the P-38 were removed first, rather it was 5 P-47, 4 P-38 then 3 P-47. A brake on the transition speed was the lack of P-51 which caused one 9th Air Force P-51 group to switch to P-47 for a while.

 

[Thumpalumpacus]

In Europe, much of the engine problems came from poor training/operation, as directed by early "on-site" commanders, the opposite of the direction of Lockheed and Allision. Specifically operating the engines at low-boost and high-rpm in cruise conditions. This does a couple of things-both bad. First, by virtue of being in low-boost, you aren't seeing much compression heating of the intake air. This means the engines are ingesting very cold air (50 below zero IIRC at upwards of 30k feet). The high-rpm condition means that you are sucking in LOTS of super-cold air. Both lead to a cold engine, cold, very thick, viscous oil that doesn't circulate properly, leading to engine failures. These same issues also lead to a cold intake manifold track, increasing the problem of fuel droplets dropping out of the intake mixture and condensing on the intake manifold. Think of taking your car, throwing it in 1st gear, and driving down the highway on a really, really cold winter morning.

"until flaps were added on later models". I think you mean boosted ailerons, which came about on the J-25-LO and all L models. These gave the P-38 one of the highest (perhaps the highest) roll rates of any WWII fighter AT HIGH SPEEDS (350mph or above). Without boost, most ailerons could not be fully deflected at high speed by the pilot. Now, you might be talking about the dive recovery flaps-these did not help turn rate from what I understand, but rather shifted the center of lift allowing for recovery from a "compressibility dive". The "standard" fowler flaps also had a "maneuver" setting on most models (IIRC starting with the F, someone correct me if I'm wrong). The flaps could be partially extended for extra lift and a tighter turn radius. I might be wrong about this, but I think the '38 actually had one of the tightest turning radii of allied or European fighters of the war (again, correct me if wrong). Where it lacked was a slow initial roll rate (lots of moment of inertia in the roll axis). But in pitch, it was always very good, from what I've read, and in a sustained turn.

Part of the problem in the ETO was that the '38 was introduced there in late-ish '43. Well, actually it was introduced in early-mid '42, then every one was shipped to N. Africa, leaving none in the ETO. It was then thrown into the long-range escort mission very shortly thereafter. With raw pilots with little training or experience. Add to that, we had a crapload of '47s (let alone Spits) available, but few '38s-and once past the range of the others-the ONLY plane in the fight was the '38. Meaning that, early on anyway, they often fought heavily outnumbered. With inexperienced pilots. Bad operating doctrine (tied to close escort with the bombers). Improper engine operating doctrine as mentioned above. With ground crews with limited experience with the type. And with questionable commanders. In comparison, the '47 was introduced much more gradually, with far more time for pilots to gain experience, and against a far less prepared, defended Europe. And in much higher numbers.

Not to say the aircraft didn't have some deficiencies (what aircraft didn't?). The "mach limit" (compressibility) issue was identified early (like 1940-41 time frame). Johnson and others at Lockheed begged to get the plane into a high-speed wind tunnel to identify the problem and formulate a solution. But the operators of those tunnels were supposedly afraid of breaking them...after a long delay it took an order from Hap Arnold to make it happen. But by then orders were flowing in, the plane was badly needed (remember, until December of '43, it was our ONLY long range, high performance, high altitude fighter) and there was resistance to making design changes and delaying deliveries. IMO one of the biggest mistakes of the war was not setting up other plants to build the '38. That would have made cutting in design changes much easier.

Thank you very much for such a detailed and informative post. And you're dead-right, I brain-farted in conflating the boosted ailerons and dive-flaps. I knew the difference, but my fingers were typing in fourth gear while my brain was in second. At any rate, your correction and distinction between the two systems is much appreciated.

 

[GrauGeist]

While Luftflotte Reich had a considerable number of single and double engined fighters, the Allies had to cross through Luftflotte 3's territory to reach German proper and depending on Allied targets in southern Germany, may have also been within Luftflotte 2's reach as well.

 

[drgondog]

To note the P-38 cockpit heating was a problem.

Is there any information the P-38 consistently fought heavily outnumbered in the late 1943/early 1944 period, since that would mean a significant percentage towards a majority of the Luftwaffe's fighter sorties were consistently hitting the P-38 formations instead of the bombers or other fighters. Interceptors including the twin engined Me410 etc. which were part of the force in the time period. Luftflotte Reich held 814 single and 198 twin engined day fighters in late May 1944, numbers that had been largely going up since 1943 even as pilot quality went down.

P-38 strength in 8th Air Force Fighter Groups, various dates in 1944.

4-Jan-44 124
11-Jan-44 130
17-Jan-44 164
25-Jan-44 212
1-Feb-44 239
8-Feb-44 180
15-Feb-44 129
29-Feb-44 170
6-Mar-44 229
14-Mar-44 268
21-Mar-44 258
28-Mar-44 262
4-Apr-44 276
11-Apr-44 269
18-Apr-44 257
25-Apr-44 256
2-May-44 255
9-May-44 245
16-May-44 283
30-May-44 276
6-Jun-44 288
13-Jun-44 318
20-Jun-44 302
27-Jun-44 290
4-Jul-44 283
11-Jul-44 269
18-Jul-44 237
1-Aug-44 109
8-Aug-44 85
15-Aug-44 77
22-Aug-44 74
12-Sep-44 50
19-Sep-44 50
10-Oct-44 21
25-Oct-44 5
7-Nov-44 1

Using Joe Baugher's web site, data is model, first month of series production.

J-1 Jan-43 (3 built then, the other 7 in June)
J-5 Aug-43 (restart of J production)
J-10 Oct-43
J-15 Dec-43 (wing leading edge fuel tanks as standard)
J-20 May-44
J-25 Jun-44 (last 210 J production, dive flaps, boosted ailerons)
L-1 Jun-44
L-5 Oct-44 (final L block number)

The US fighter evaluation in 1944, turning, best was the FM-2 at 100 units, the P-51D-15 was 5th at 179, the P-38L 205, the P-47D-30 206. 1G, no flaps.

Quote,

The -25 mainly fixed Lockheed's flight control issues. Allegedly the intake problem overstressed Allison's small engineering team. The behavior of liquid / gas mixtures under extreme conditions is the core of "rocket science" and it was very rare knowledge back then, before computers enabled Computational Fluid Dynamics.

The P-38 Lightning

"To be more specific, the foremost problem was the temperature of the compressed air from the turbosupercharger entering the carburetor. High carburetor air temperature (CAT for short) can cause all kinds of engine problems including detonation, which can lead to catastrophic engine failure. Allison recommended a CAT of no more than 45 degrees C."

"As it turned out high CAT was one of the major problems limiting P-38 performance through the P-38H. The root cause was, of course, the limited cooling ability of the wing leading edge intercoolers found in all early P-38s. They were a very clever design, inducing almost no aerodynamic drag, but they were designed for the 1000 hp Allisons of the late 1930s. By 1943 Military power was up to 1425 bhp and War Emergency Power was 1600 bhp. The increased power required higher induction pressure, which through compression by the superchargers heated the air by several hundred degrees. There is no way that the simple intercoolers could keep CAT below 45 degrees C. when operating at high power at altitude."

CAT wasn't the only problem though. The centrifuge effect of the compressor and the temperature variations in the plumbing could separate out the heavier octane enhancing additives and worsen the destructive detonation. The scientists who really understood this stuff were elsewhere separating Uranium.

The planes performed better in the warmer Med and Pacific so that's where they went. Doolittle and Spaatz made the decision to use the available and very suitable Mustang instead of waiting past D-Day for large numbers of a better P-38 in a paper that I haven't been able to find online. This gives an excerpt:

http://www.amazon.com/forum/military%20history?cdForum=Fx5TS2W4P5EMS6&cdPage=2&cdSort=oldest&cdThread=TxZW9V919NXLHM

" A lot of this had to do with its poor intake manifold design, something that Gen. Jimmy Doolittle, who had a PhD in aviation science from MIT, pointed out in a report on the P-38's problems, written to Carl Spaatz in the spring of 1944."

"Doolittle specifically singled out the intake system of the V-1710 as a problem - the tetraethyl lead was somehow separating out with the uneven distribution which caused repeated problems with detonation in certain cylinders in the V-1710s (i.e., they would blow up and catch fire in flight - kinda nasty for the pilots, eh?)."

***"Doolittle's letter to Spaatz is about as clear cut of an explanation of the problems of the V-1710 - turbosupercharger combo at high altitude in Europe as any I've ever found. It's the smoking gun that answers the question of why the P-38 was pulled from almost all combat duty in Europe, remaining only as a photo-reconnaissance plane."***

The dive brake modification shows how long it could take to field a fix on that plane.

Fred Colvin's writing on war production illuminates the difficulty of finding the proper curvature for efficient turbocharger and jet engine compressor blades. Unable to calculate it, the scientists were demanding that the shop produce a variety of exotic and difficult-to-machine mathematical spirals to determine by experiment what was best.

http://people.math.umass.edu/~tevelev/475_2014/beittel.pdf

"However the Archimedean spiral is used in a variety of applications. One such interesting application is in scroll compressors."

End quote

Early 8th AF escort operations,

P-38 operations with the 8th AF started on 15 October 1943. The P-51 started escort operations in December 1943.

First escort mission, 20 October, 39 P-38, no kill claims, 321 P-47, 6 kill claims. No USAAF fighters MIA.

table is date / number of P-38 / P-38 kill claims / P-38 MIA // number of P-47 / number of P-47 kill claims / P-47 MIA. Bomber escort missions only

3 November / 45 / 3 / 0 // 333 / 11 / 2
5 November / 47 / 5 / 0 // 336 / 13 / 4
7 November / 0 / 0 / 0 // 283 / 1 / 0
11 November / 59 / 0 / 0 // 342 / 8 / 2
13 November / 45 / 7 / 7 // 345 / 3 / 3
19 November / 0 / 0 /0 // 288 / 0 / 0
26 November / 28 / 0 / 0 // 353 / 36 / 4
29 November / 38 / 2 / 7 // 314 / 13 / 9
30 November / 20 / 0 / 1 // 327 / 0 / 5
1 December / 42 / 0 / 5 // 374 / 20 / 2

The third set of figures is for P-51

5 December / 34 / 0 / 0 // 266 / 0 / 1 // 36 / 0 / 0
11 December / 31 / 0 / 0 // 313 / 20 / 3 // 44 / 0 / 1
13 December / 31 / 1 / 0 // 322 / 0 / 1 // 41 / 0 / 1
16 December / 31 / 0 / 0 // 131 / 1 / 1 // 39 / 1 / 0
20 December / 26 / 0 / 0 // 418 / 16 / 2 // 47 / 3 / 4
22 December / 40 / 0 / 2 // 448 / 9 / 2 // 28 / 6 / 0
24 December / 40 / 0 / 0 // 459 / 0 / 0 // 42 / 0 / 0
30 December / 79 / 0 / 0 // 463 / 8 / 11 // 41 / 0 / 2
31 December / 74 / 3 / 1 // 441 / 4 / 2 // 33 / 2 / 1

Totals, P-38 749 sorties, 21 kill claims, 23 MIA, P-47 6,877 sorties, 169 kill claims, 54 MIA, P-51 351 sorties, 12 kill claims, 9 MIA.

The first 8th Air Force mission using P-38J models of any type seems to have been on 28 December 1943. The 8th AF loss lists note H-5 losses to November 1943 to early January 1944, J-5 losses early January to September 1944, J-10 losses early January to June, J-15 mid April to September. No J-25. The ETO first P-38 group to have J-25 or L model was the 479th in August 1944, they were given 2 and found the dive flap system unreliable and so had the aircraft replaced with non dive flapped models. In October 1943 the USAAF in Britain had 105 P-38 and 159 P-51, in November it was 188 to 231, in December 380 to 266. In January 1944 it was 637 P-38 to 543 P-51, in February 669 to 699 and the P-51 stayed ahead for the rest of the war. These figures includes reserves

The following time line is 1943 to 1944, mainly from Air War Europa by Eric Hammel.

20th December The first freelance fighter mission is flown when the bombers turn up 30 minutes late and the 55th fighter group "puts into action a plan much discussed by fighter pilots - ranging ahead of the bombers as they converge on the bomber path. The 55th fighter group scores no victories on this day, but its new tactic gets the attention of VIII fighter command and there ensures a healthy debate that, in the end, will free the fighters from the outmoded close-escort doctrine of the day." Window is first used on this day as well. Some 491 fighters were used as escorts for 546 bombers, 12 of which were pathfinders.

6th January Doolittle gained command

7th January Phased escort tactics used, fighters fly to rendezvous points to relieve other fighters rather than a formation of fighters stays with a formation of bombers for the entire mission, 571 fighters for 502 bombers.

11th January the first officially sanctioned test of freelance fighter tactics, where fighter formations range ahead and to the side of the bomber formation hoping to catch Luftwaffe fighters as they are forming up, 592 fighters for 663 bombers. The USAAF mounts 2 raids that day, the one with the freelance experiment, to Oschersleben and Halberstadt, has the Oschersleben bomber formation hit hard by fighters and flak, losing 34 from 177 bombers despatched, the Halberstadt formation loses 8 from 114 despatched. The 221 escorting fighters for these two formations claim 29 kills for 3 fighters lost, 11 of the kills by the freelance fighters. Only the 56th fighter group freelances, with two formations of 36 and 48 fighters respectively. All the bombers were B-17s.

The second raid that day, to Brunswick, was largely reduced to targets of opportunity and lost 16 B-17s and 2 B-24s.

Of the 58 to 62 B-17s lost that day (sources vary again), including write offs, some 44 were lost to enemy fighters, 8 to flak, 2 to "battle damage" and 5 "operational" losses, according to my counts.

So the initial experiment would have a mixed report, the freelance fighters did above average but the bombers were clearly exposed to significant fighter attack.

21st January 56th fighter group turn in the first strafing kill claims, it is not until late March that strafing becomes a significant source of kill claims. In April according to the USAAF statistical digest fighters will lodge 418 kills in the air and 527 on the ground, versus 469 in the air and 76 on the ground in March.

24th January the first attempt at having fighters patrol an area for a time, not stick with a particular bomber formation, abandoned due to weather problems.

Ignoring 1942, when the first 8th Air Force P-38 group flew its first mission mid October 1943, there were 7 P-47 groups flying missions. The second P-38 group flew it first mission at the end of December. The third group flew its first mission in early March 1944, by which stage the 8th had 2 operational P-51 groups and was borrowing the 9th AF ones. In late May it was 4 P-38 to 7 P-51, by end July it was 1 P-38 to 10 P-51 groups flying missions.

8th AF P-38 units,
The 20th FG claimed 76 kills November 1943 to June 1944,
the 55th FG claimed 79 kills November 1943 to June 1944,
the 364th 35.5 kills March to June 1944,
the 479th 70 kills June to October 1944.

So around 260 kill claims. USAAF ETO fighters made 2,706 kill claims November 1943 to June 1944.

In terms of failed to return the 8th lost something like 257 P-38 November 1943 to October 1944.

Using the USAAF unit history and the USAAF kill claims lists I make the P-38 groups in the ETO as

20th sent 8/43 1st kill claims 11/43 converted to P-51 7/44 scored 90 out of wartime total of 209.5 kill claims in P-38s.
55th sent 8/43, 1st kill 11/43 P-51 7/44 106 of 303.5 kills in P-38s.
364th sent 1/44 1st kill 3/44 P-51 7/44 35.5 of 263 kills in P-38s.
367th sent 3/44 1st kill 6/44 P-51 3/45 74 of 85 kills in P-38s
370th sent 1/44 1st kill 5/44 P-51 2/45 37 of 38 kills in P-38s
474th sent 2/44 1st kill 7/44, 95 kill claims, only ETO P-38 group in May 1945.
479th sent 4/44 1st kill 6/44 P-51 11/44 75 of 154 kills in P-38s.

Note the kill claim breakdowns are based on everything up to and including the month of conversion counted as P-38 kills. Of the 7 groups 4 scored more kills after conversion to P-51. The P-38 arrived in the 8th Air Force around 7 weeks before the P-51 (or 9 bomber escort missions) and like the early P-51 had less internal fuel than later models. While until the second P-38 group flew combat at the end of the month there were more P-51 on escort than P-38 in December.

The 8th Air Force P-38 immediately hit a series of mechanical problems that had not been obvious in other theatres, the combat performance was also a problem. Even so as can be seen the P-38 strength in the 8th Air Force stayed high until July 1944. It was 2 groups at the end of 1943, 3 in early March 1944, 4 end May 1944, down to 1 by end July, to zero mid September, all moving to the P-51. Meantime it should be noted the 8th transitioned some P-47 groups earlier, it had 9 P-47 groups end January 1944, and that was down to 4 by mid May, 3 more P-47 groups converted in the final quarter of 1944. So it was not a case of the P-38 were removed first, rather it was 5 P-47, 4 P-38 then 3 P-47. A brake on the transition speed was the lack of P-51 which caused one 9th Air Force P-51 group to switch to P-47 for a while.

A lot of compiled and presented data, but left me wondering what your primary message is?

A few notes occurred to me as I agreed with most data you presented.
1. The 'relay' system per se began in June 1943, when VIII FC differentiated Ramrod (Escort) to target and introduced Penetration, Target and Withdrawal to further refine the 'relay' leg as the VIII began build up of P-47C and early D equipped Fighter Groups. Target support was a dream for east Netherlands and Belgium and France and west Germany - until the introduction of the 200 gal ferry tank on the C/L bomb rack in late July.
2. The quantity of 8th AF fighter types was an interesting disclosure, but like many similar statistical presentations framing discussions of Escort and Combat, only the operational numbers dispatched, effectives and MIA and Damaged enable clarity at the point of the spear on a monthly basis. For example, the 55th FG went operational as a complete FG. In early November one squadron of 20th FG (77th) went operational attached to the 55th FG until 20th went operational. The 55th and 79th also flew in early December until the complete 20FG made its first mission on 28 December, 1943.

To this point, there were approximately 70-80 (average) P-38s each at 20th and 55th FG, plus 7 Recon, plus 495 FTG through December into January 1944, plus more P-38s arriving for the 364th FG training - but only 70 were available for operations out of the 124 you cited for Jan 4. 70 dispatched, not including aborts for two complete operational P-38 Fighter Groups. So, the tabular strength of VIII AF on a daily basis was roughly 50% more than could actually be sent into combat.

The dive flap kits began installation in June/July for the P-38-10 and J-15. The P-38J-25 at 479th FG was indeed there for familiarization in late August, but the J-10/J-15s had the dive flap mods applied, as well as installed 2nd generators to augment cockpit heating. The 479th had a very capable P-38J-10/-J-15 in combat operations in September 1944.

Your comment that 'while there were 2 P-38 FG in December 1943 an only one P-51 FG, the P-51 had more on escort' is true - but only because the P-51B had fewer aborts than the 55th FG through the first 20th FG op on 28 December.

While I respect Eric Hammel, I never extract a statement as accepted truth without other sources. The comment that the first use of chaff/window on Dec 20th kinda overlooks the Hamburg strikes in Blitz Week July 1943? His comments on first use of Relay System I addressed above.

The use of the noun "Freelance' is overused in the Hammel renditions. Assigned Sweeps in front of a Task Force became a common tactic when enough fighters were available to assign at least 1 escort FG tethered to a BD and free up other P-51/P-38 FG to Sweep Target ahead of the Bomb Groups.