P-38 vs Spit XIV

[pasoleati]

But was the wing design the sole culprit for the low CMN? IIRC the Typhoon has approx. similar wing thickness yet it has much higher CMN (according the Eric Brown´s Testing for Combat the true CMN was 0.81, i.e. very close to that of the Mustang).

[Captain Virgil Hilts]

Originally posted by pasoleati
But was the wing design the sole culprit for the low CMN? IIRC the Typhoon has approx. similar wing thickness yet it has much higher CMN (according the Eric Brown´s Testing for Combat the true CMN was 0.81, i.e. very close to that of the Mustang).

Yes, it was mostly a factor of the wing design. There were other issues that made it worse.

Great care had to be taken with the fit of everything around the windows and the rest of the center nacelle.

[Captain Virgil Hilts]

Originally posted by Captain Virgil Hilts
Yes, it was mostly a factor of the wing design. There were other issues that made it worse.

Great care had to be taken with the fit of everything around the windows and the rest of the center nacelle.

I was interrupted, so I'll quote what I started.

As stated above, the fit in finish in that area was CRITICAL, even the adjustment on the roll up windows and how they fit and sealed could make a huge difference.

There was likely more that could have been done to deal with the compression issues the P-38 had. Early on, they reworked the fillet radius between the inner wing and the center nacelle, and were rewarded with dramatic improvements. Kelly Johnson wanted desperately to work on the problem, but was not allowed to use the wind tunnel that belonged to NACA (the forerunner of NASA), and was forced to do all of his testing at altitude and speed, risking the lives of test pilots and the planes. At least one test pilot was killed during compression dive testing, and the plane was destroyed as well. Without wind tunnel data, they could not SEE what was happening, and had to rely on pilot "feel" and trial and error guesswork.

There is NO QUESTION that compression was a serious issue, it was the single biggest problem that faced the P-38, and even with wind tunnel testing would not have been easily dealt with. However, there is little doubt they could have done MUCH more than they did, given wind tunnel time and a free hand.

Yes, the P-38K could have come close to reaching compression in level flight at critical altitude. HOWEVER, rarely was any fighting done at top speed flying level at that altitude. Remember, no one cruised at 100% throttle like we do in AH, so rarely did anyone even enter combat at the maximum level speed. The only time combat was initiated at top speed was when one opponent was able to dive on another. It takes quite a while to accelerate from the average cruise speed of 260-300 MPH up to speeds in excess of 440 MPH unless you dive.

Taken a step further, even if you DID enter combat at 450MPH, after the first turn you'd lose considerable speed. This is EASILY demonstrated.

Take ANY fighter in AH, and accelerate to its maximum level speed at ANY altitude, and then execute any sort of break turn or other merge move you'd make, and then look at your speed at the end of that maneuver. Unless you dive, it will not even be equal to the speed you had when you merged, never mind faster. Execute a 2-3G merge maneuver level or climbing, and see how much speed you LOSE.

At this point, power to weight ratio (the P-38J and L were pretty decent in that department already) and prop efficiency are CRITICAL to maintaining speed and E, or at least limiting the loss of speed and E. The P-38 Curtiss Electric prop, supplied by the USAAF, just plain SUCKED. It was terribly inefficient, unreliable, and was a huge load on the electrical system. One of the guys here in AH, Earl "Dutch" Miller, flew the P-38, P-39, and P-47 in World War II. He said the Curtiss Electric prop was the biggest piece of crap he ever saw. Given the choice, he avoided planes that had one at all costs.

At this point, it should be noted that the USAAF/USAAC and the War Production Board specified and/or supplied the parts a manufacturer used to build aircraft. Even if the engineers stated it was a poor or even dangerous choice, the manufacturer did NOT have any say.

The P-38K had OVER 400 more horsepower available than the P-38J, and over 200 more than the P-38L, (and we DO NOT get the 200 HP gain from the J to the L in AH). But the P-38K also had a 20% more efficient prop. If you'll look at the difference between a paddle prop (Hamilton Standard High Activity Paddle Prop) P-47, and a P-47 with the Curtiss Electric prop like the P-38, you'll see a DRAMATIC increase in performance including a huge increase in climb rate. There is no reason to expect that the P-38 would have gained ANY less than the P-47 did with the prop change. The gain would have been huge, even without the added power.

Even if NOTHING else had been done to cure the compression problem, the drawback for the P-38 would have been a top speed limit of 450-460MPH, give or take 5-10MPH. The rest of the gains in acceleration, climb rate, speed and E retention, and sustained turn rate would have been more than enough to compensate.

[Squire]

My understanding is the USAAF had decided to go with the P-51 Mustang as its premier escort type, and thats why the P-38s were gradually phased out.  The remaining P-38Js and P-38Ls in the IXth Tac AF were employed in various roles untill the end of the ETO campaign.

By the summer of 1945 the war with Germany was over, and they were looking for a long range escort for B-29 groups, and were still envisioning the P-47 as the USAAFs main ground attack fighter in case of an invasion of Japan, and P-51s as escort/air superiority fighter.

Strategic interests often decided the fate of certian a/c types, either by deployment or a change in strategic fortunes on all sides in the war.

My point being that ordering a P-38K varient would seem redundant given those facts, despite its promise as a type.

[Urchin]

Captain, the P-38L in AH should have 200 more HP than the P-38J does?  

I thought we had a late model P-38J that was for all intents and purposes identical to the L.

Explain, please.  Thanks in advance.

[Ack-Ack]

We have an early model J without the dive flaps and boosted ailerons.



ack-ack

[Captain Virgil Hilts]

Originally posted by Urchin
Captain, the P-38L in AH should have 200 more HP than the P-38J does?  

I thought we had a late model P-38J that was for all intents and purposes identical to the L.

Explain, please.  Thanks in advance.

Okay. This is a subject of great debate. Let me first post a data chart, it's the chart Warren Bodie gave me as well as Widewing. It is taken directly from the Lockheed and Allison tests on the -30 Allison engines installed in the P-38L.

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



Now, the USAAF did not release these specs, choosing instead to retain the earlier specs for the J model. However, Lockheed reps went into the field and showed the pilots and crews the true settings. Not all pilots and crews knew about it.
Captain Art Heiden regularly refers to the P-38L as having significantly more power than the P-38J, and the ONLY explanation I can find for this would be the use of the real settings by Art and his crew.

Now, Warren Bodie was a Lockheed engineer for 30 years or so, and worked in the legendary Skunk Works with Kelly Johnson and crew. Here is the Lockheed test data for the P-38L, Warren provided from the Lockheed test logs.

(from Lockheed factory test logbooks):
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.

Now, in this passage we have an explanation of the factual data for the P-38L compared to the P-38J, as found in the Lockheed test logs, again according to Bodie. I'm going to use a quote from Widewing that I have saved, because it is easy to access and paste here, but it is verified DIRECTLY by Warren Bodie himself, I have seen the actual copies of the log books.

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.

Again, note I specifically state this is pasted from a post by Widewing, but that I verified with Bodie, I did see the logs.

Now, the reason HTC did not model the P-38L with the more powerful engines and the faster speeds is that the USAAF/USAAC never accepted the ratings, at least officially, this we ALL agree on. The settings WERE used by combat units, there is NO DOUBT of this. But without official acceptance, there are too many arguements against it, so HTC did not model it.


Recently, Pyro clearly stated in a post on the boards when the recently added P-38's were being coded, that he had verified reports that the 8th AF was actually allowing P-38's to be run at higher than accepted power settings. He did not elaborate. However, everyone agreed it was probably best not to model them that way.
 

Now regarding "our" P-38J. It is either a P-38J-5-Lo, a P-38J-10-Lo, or a P-38J-15-Lo. All of those models were originally shipped WITHOUT the boosted ailerons and the electric dive FLAPS. Some were retrofitted later in the field. But most of the parts for retrofits were lost when a Spitfire shot down a U.S. cargo plane and the plane crashed into the sea (at least that is the report).

When the "new" P-38's were being coded, we actually campaigned to have an earlier J model, rather than the P-38J-25-Lo, because it would be completely redundant.

So, AKAK is correct in his post.

Now, I personally would like to have had a P-38H-10-Lo as opposed to the P-38G, because it was the H that the 20th and 55th went operational with in late 1943. The J arrived in December 1943 in very small numbers, and the late J did not arrive until early 1944. The L arrived in mid 1944, just as the 8th was transitioning to the P-51D.

[Captain Virgil Hilts]

Originally posted by Squire
My understanding is the USAAF had decided to go with the P-51 Mustang as its premier escort type, and thats why the P-38s were gradually phased out.  The remaining P-38Js and P-38Ls in the IXth Tac AF were employed in various roles untill the end of the ETO campaign.

By the summer of 1945 the war with Germany was over, and they were looking for a long range escort for B-29 groups, and were still envisioning the P-47 as the USAAFs main ground attack fighter in case of an invasion of Japan, and P-51s as escort/air superiority fighter.

Strategic interests often decided the fate of certian a/c types, either by deployment or a change in strategic fortunes on all sides in the war.

My point being that ordering a P-38K varient would seem redundant given those facts, despite its promise as a type.

The problem with that theory is that the P-38K was built and tested around March/April 1943. BEFORE the J or the L.

At that point, no decision had been made about replacing the P-38 with either the P-51 OR the P-47. In fact, at the time the P-38K was being tested, there were no operational P-51 groups in the 8th at all, and they had decided the P-47 was not acceptable as a long range escort (ANOTHER mistake on the part of the 8th AF).

The P-47 was only escorting the bombers to the German frontier, they were going it alone after that. AND at that time the P-47 was the ONLY fighter escort, and was doing as good a job as possible, considering that they could not go into Germany due to lack of range. The first P-38 group had not even gone operational with the 8th AF at that point, ALL of the P-38's originally intended for the escort duty with the 8th AF had been sent to the Med theatre or North Africa. Since the first of the P-38J's arrived in December 43/January 44, that is when they'd have had the P-38K with the improved performance.


Even in LATE 1943, LONG after the P-38K was rejected, the P-51 STILL had not been chosen to replace the P-38.

And again, remember that the K was developed and tested BEFORE the J and L. So they got the J and L, but not the K. If the K would have been redundant, then the J and L certainly would have.

[Squire]

I was thinking more along the lines of if say they had "revisited" the P-38K option as an ETO/PTO fighter. Perhaps they did, but by that time the P-51B/D was flagged as the premier US type.

[Captain Virgil Hilts]

Originally posted by Squire
I was thinking more along the lines of if say they had "revisited" the P-38K option as an ETO/PTO fighter. Perhaps they did, but by that time the P-51B/D was flagged as the premier US type.

To my knowledge, once the P-38K was rejected in early 1943, it was never reconsidered or resubmitted.

The MAIN reason the USAAF/USAAC and War Production Board gave for the rejection was that Lockheed asked for two weeks production shutdown in order to change the cowl and spinner area, because the new prop and gearbox required the centerline of the prop shaft to be raised. This request was denied, because P-38 production was deemed so critical that any interruption was too terrible a burden, evidently they felt they needed the P-38 that bad. The 5th AF and the 9th AF in particular constantly lobbied, begged, and pleaded for more P-38's, and would actually take even War Wearies from other Air Forces just to have the P-38 because it was what they wanted and needed.

The Lockheed plant that built the P-38 actually devoted more space and man power to the B-17 than to the P-38, considerably more. Consolidated Vultee in Nashville Tennessee was contracted to be the second source for the P-38, I have family that worked there. Unfortunately, Consolidated was actually a company devoted to bomber and transport aircraft, and did not possess ANY of the staff in production, engineering, or management that was experienced with and capable of dealing with the precision manufacturing process needed to produce the P-38. As a result, after at least two years of trying, they barely built 113 P-38's, where I seem to recall the contract called for around 2500 or so (possibly 3000-3500, I do not have the reference for that handy).

P-38 production was actually done outside the plant under camo nets for a long time, while the B-17 production occupied precious indoor production space.

Consolidated would have been a far better choice to build the B-17's Lockheed was tasked with producing, they would have done at least as well as Lockheed at building B-17's, and surely doubling plant capacity for P-38 production at Lockheed's plant would have resulted in a wealth of P-38's, and the ability to shut down only one line at a time, thereby not interrupting the only source for the precious P-38's that were so desperately needed.

Anyway, only the 8th AF actually stopped requesting P-38's, everyone else begged for them. The P-38 production was not reduced or phased out until the war ended, it ran wide open from the beginning of the war until after hostilities ceased.

On a side note, the USAAF/USAAC also wasted considerable Lockheed engineering resources on projects like the "Chain Lightning" and other bizarre versions of the P-38, and they (the USAAF/USAAC) continually screwed up those projects and changed the design specifications so that little real progress was ever made. The engineering time and resources would have been far better devoted to either the REAL P-38 program, or the P-80 program, both of which would likely have progressed far more rapidly with far better results.

[Urchin]

Interesting information Captain, thanks.  I've heard similar stories of the P-47 running at settings that weren't "offically" allowed without much trouble.  

Probably be something cool to throw in TOD anyway.  No idea how the bonuses will work, but maybe one of them will be a '1337' crew chief that can overboost your engines safely .

[Captain Virgil Hilts]

Originally posted by Urchin
Interesting information Captain, thanks.  I've heard similar stories of the P-47 running at settings that weren't "offically" allowed without much trouble.  

Probably be something cool to throw in TOD anyway.  No idea how the bonuses will work, but maybe one of them will be a '1337' crew chief that can overboost your engines safely .

Yeah, Republic took a P-47 engine and ran it for about 24 hours at 80" of MAP. The P-47 was regularly run well above the factory boost ratings. That's a little different than the -30 Allisons in the P-38, those being run BELOW the FACTORY ratings.

The -30 Allisons in the P-38L were about the only engines that were not accepted to run at the factory ratings for both the plane and the engine, from both manufacturers.

[Crumpp]

Interesting.

It appears that the BMW801D was also overboosted by some pilots.

I have a report from BMW investigating the practice of overriding the Kommandgerät limiter and increasing the manifold pressure in 1944.  The report concludes that the practice should cease immediately as it is dangerous to both the aircraft and the pilot.

Several months later the boost pressure was officially raised by BMW.

All the best,

Crumpp

[Captain Virgil Hilts]

Yeah, I'm pretty sure there was a lot of overboosting going on just about everywhere. Mechanics will always be mechanics, and about 90% of the GOOD ones are dyed in the wool hot rodders. Any good hot rodder will push the engine as hard as he thinks he can get away with.

Since there's no way to model how soon an engine will fail when it is pushed past the factory limit, and HTC made a decision (and probably a wise one) not to model random engine failures (or even deal with quality control issues known to exist at certain times in certain planes) there's no way to deal with boosting an engine past the factory limits.

Much as I'd LIKE to see the P-38L get the properly modeled -30 Allisons at their correct factory rated output, I understand the position of HTC, even though I know that the higher rating was approved by GM/Allison and Lockheed, and I know pilots who used it.

[bolillo_loco]

Over the years I have read quite a bit of P-38 vs the Luftwaffe and how the P-38 was not up to the task. To back up these claims the performance of the P-38 in the long range escort role during service in the 8th airforce is frequently used. It is frequently stated how well 8th airforce units did once they switched to the P-51. Nobody will ever know how well the P-38 would have done had the P-51 never showed up. It is not a fair compairson to compair 2 P-38 fighter groups performance during late 1943 to early 1944 when there were very few long range escorts. The P-38 units were greatly out numbered and the escort tactics that the 8th airforce were not as effective as they could have been. I think the only way to truely judge how the P-38 performed vs the P-51 is to look at how the 4 fighter groups that used P-38s performed the month prior to recieving P-51s the month they operated both P-38s and P-51s and the month after P-38 ceased operations. The reason for this is simple. during the 3 month period the fighter units faced similar opposition and the americans had a similar number of fighters on hand.

the data I have compiled represents how the 20th fighter group, 55th fighter group, 364th fighter group, and 479th fighter group of the 8th airforce performed during a specific time frame.

The 20th, 55th, and 364th fighter groups operated the P-38 during the month of June 1944, a mixed group of P-38s and P-51s during the month of July 1944, and the P-51 during the month of August 1944. The 479th fighter group operated P-38s during august 1944, a mixed group of P-38s and P-51s during September 1944, and the P-51 during October 1944.

during the above mentioned time the 4 fighter groups claimed the below mentioned figures. Figures which were revised from the original war time claims by a study done well after the war ended. many claims were disallowed, confirmed, or left stand after a close examanation of german and american records.

P-38 destroyed 214, probably destroyed 6, damaged 102, 60 P-38s were lost to all causes.

P-51 destroyed 91, probably destroyed 1, damaged 23, 68 P-51s were lost to all causes.

air to air only

P-38 destroyed 112, probably destroyed 6, damaged 35, 10 P-38s were lost to enemy aircraft.

P-51 destroyed 91, probably destroyed 1, damaged 23, 3 P-51s were lost to enemy fighters.

*Note the 55th fighter group lost 8 of the 10 P-38s lost to enemy aircraft.

I also found it interested that mechanical failure is always mentioned for P-38 losses in many books. during this period of time more P-51s were lost due to mechanical failure than P-38s.

P-38s lost due to mechanical failure - 5
P-51s lost due to mechanical failure - 13

Hub Zemke is often quoted in forums as staying that one the P-51s replaced the P-38s the 479th did much better. He is also quoted in many forums as stating P-38s had a very high abort rate and mechanical failure was the cause. Lets take a look at Hub Zemke's time spent with the 479th. Zemke arrived about a month before the 479th began their transition into the P-51. August 12th 1944 I believe. On September 12th 1944 the 479th began their first missions with P-51s and they flew a mixed bag of P-38s and P-51s until October 2nd 1944. Zemke was lost during October 1944. I do not understand how Zemke came to his conclusions in light of the 479th statistical record for this time period, or his is often misquoted in forums.

P-38 August 12th 1944 thru September 11th 1944: 1,143 sorties 114 aborts, abort rate .10%
P-38 September 12th 1944 thru October 3rd 1944: 355 sorties 26 aborts, abort rate .07%
P-51 September 12th 1944 thru October 3rd 1944: 262 sorties 30 aborts, abort rate .11%
P-51 October 5th 1944 thru November 5th 1944: 780 sorties 67 aborts, abort rate .09%


total for both aircraft during this period

P-38 1,508 sorties 140 aborts, abort rate .09%
P-51 1042 sorties 107 aborts, abort rate .10%

479th scoring for the above mentioned time.

P-38 destroyed 150, probably destroyed 1, damaged 78, 16 P-38s lost to all causes

P-51 destroyed 14, probably destroyed 0, damaged 3, 12 P-51s lost to all causes.


air to air only

P-38 destroyed 49, probably destroyed 1, damaged 14, 1 P-38 lost to enemy aircraft

air to ground only

the P-38 destroyed 101 and damaged 64

P-51 destroyed 14, probably destroyed 0, damaged 3, no P-51s lost to enemy aircraft.

air to ground only

the P-51 had no claims for this period

the 16 P-38s the 479th lost during this period:

1 to enemy aircraft
11 to enemy flak
2 crashed/accidents
1 due to mechanical failure
1 no explanation other than KIA

the 12 P-51s the 479th lost during this period:

0 to enemy aircraft
2 to flak
4 crashed/accidents
3 due to mechanical failure
3 no explanation other than KIA

I am not certain why the MTO is frequently over looked. in the MTO the P-38 performed high altitude fighter escort for heavy bombers to targets including germany itself as well as nearly ever country germany occupied during the war. Just as in the 8th and 9th airforce the P-38s were greatly out numberd by P-51 and P-47 units.

air to air claims

1,431 - P-38
1,063 - P-51
203 - P-47

look at how the 15th airforce (MTO P-38 unit) performed against the germans.

44,296 sorties
3,814 early returns due to all causes
.086 abort rate due to all causes
608 enemy aircraft destroyed in the air
131 lightings were lost (not sure if it was to all causes)

the 15th airforce compairs favorably to P-51 and P-47 units in the ETO. the 12th fighter group (P-38 unit) also did fairly well.