Alternate Approach to the P-38 Compressibility Problem (1 Viewer)

[tyrodtom]

Go do a search on Youtube is the best thing I can tell you.

Within the video they cited specific units, dates and pilot names as well as the release of directives by 8th AF, but where else you'd find them I do not know. I am surprised that Warren Bodie's monumental work on the P-38 did not mention this, that I can recall.

On the other hand I saw a video a little while back on Youtube about the P-38 that I am at least 90% sure is fabricated bunk, but I have not yet done the research to find out definitely.

Did you check the specific units, dates, and names and see if they actually can help confirm the information.
I seen a lot of recent videos on U-tube that try to flood you with information, that on investigation, turns out to be just flat out fabrications.

 

[ssnider]

Another Eric Brown dive performance that does not lineup with other testing.

View: https://www.youtube.com/watch?v=SqG_UO2bJbQ

British test pilot Roland Beamont comments on FW 190 dive performance:
At its Vne (dive limit) of approximately 500mph IAS the controls were noticeably heavy and rate of roll slowing, whereas the Tempest V was unaffected and retained high-rate roll at its Vne of 545mph — the highest dive speed of any fighter of the period. This was significant, as the Spitfires IX and XIV were limited to 450 and 465mph respectively and only the P-51D (and Mustang III) had a higher limit at 485mph;

Attached a typical test report

 

[Dimlee]

MIflyer was likely referring to this video:

View: https://www.youtube.com/watch?v=tqT6LUz8GME

A more elaborate video about this:

View: https://www.youtube.com/watch?v=dsxTh8Lgdc8&t=559s

I like those pictures. Secret aircraft projects of the USAAF? Extra scenes from the Sky Captain and the World of Tomorrow?

 

[Shortround6]

A "how many different aircraft parts can you spot" game?

 

[MIflyer]

It is certainly possible that Brown made a mistake.

As is shown by his marvelous 'Wings Of" books he kept detailed notes of his flights and impressions of aircraft as well. Wings of the Luftwaffe is his best, and it is available on ebay for $9 or less, but his Wings of the Navy is as well.

 

[emu27]

His father was a WW1 pilot who got to know a number of the German pilots

Browns Father was not a pilot, "Wings on my Sleeve" contains a lot of trash and is not a biography. Best have a read of "Winkle" by Paul Beaver for the truth.

 

[Writer]

The BF-109 and FW-190 had heavy elevators, especially at high speed, so much so that it imposed limitations from pulling out of dives. So maybe they were disinclined to go fast enough to encounter compressibility.

I had read of the Bf-109 having heavy elevator controls but never the FW-190 and I have read a lot of books about both...

 

[Engineman]

Another Eric Brown dive performance that does not lineup with other testing.

View: https://www.youtube.com/watch?v=SqG_UO2bJbQ

British test pilot Roland Beamont comments on FW 190 dive performance:
At its Vne (dive limit) of approximately 500mph IAS the controls were noticeably heavy and rate of roll slowing, whereas the Tempest V was unaffected and retained high-rate roll at its Vne of 545mph — the highest dive speed of any fighter of the period. This was significant, as the Spitfires IX and XIV were limited to 450 and 465mph respectively and only the P-51D (and Mustang III) had a higher limit at 485mph;

Attached a typical test report

Interesting,
Mustang limit 485mph? I have a copy of a combat report from November 1944 with a P-51D reporting 550mph in combat with Me 262.

Eng

 

[GregP]

Logically, I do not see how shutting down one engine would solve the problem. The P-47 had the same problem with compressibility. It is with air flow starting to go supersonic over the wings. Then again, I am no expert and could be wrong.
Question for the experts here. Did either the Me-109s or the Fw-190s have similar problems with compressibility?

Logically, there is no reason why having the P-38's engine turn inwards would cause the aircraft to be unable to lift off, but thath happened. So, tey changed the engines to outward-turning, and the issue "went away." Doesn't seem to be a logivcal explanation for that one, either, but the solution is real and well-documented.

Perhaps this is just another really odd thing about the P-38.

Stranger things have happened ...

 

[Thumpalumpacus]

Logically, I do not see how shutting down one engine would solve the problem. The P-47 had the same problem with compressibility. It is with air flow starting to go supersonic over the wings. Then again, I am no expert and could be wrong.
Question for the experts here. Did either the Me-109s or the Fw-190s have similar problems with compressibility?

My understanding is that with the P-38 the compressibility issue was more about the speeded airflow over the wing blanking or locking the horizontal stab control? Or am I just saying the same thing a different way? I thought that the way the wave of air from the wing hit the hori stab, it either lost effectiveness, or induced destructive vibration.

I'm not clear on the P-47's similar issues. If you or someone else can help me get that, I'd be appreciative.

 

[KLS&C 85]

My understanding is that with the P-38 the compressibility issue was more about the speeded airflow over the wing blanking or locking the horizontal stab control? Or am I just saying the same thing a different way? I thought that the way the wave of air from the wing hit the hori stab, it either lost effectiveness, or induced destructive vibration.

I'm not clear on the P-47's similar issues. If you or someone else can help me get that, I'd be appreciative.

From my reading with the P-47, compressibility would cause the stick to feel like it was in concrete. It was unmovable until the airplane got into thicker air causing the Mach number to decrease. Then the pilot could regain control.
WWII was a time when some of the aircraft outran our knowledge of aerodynamics!

 

[emu27]

there is no reason why having the P-38's engine turn inwards would cause the aircraft to be unable to lift off, but thath happened. So, tey changed the engines to outward-turning, and the issue "went away." Doesn't seem to be a logivcal explanation for that one, either, but the solution is real and well-documented

The reason the production P-38 turn in the direction they do is all to do with the pitching moment, makes for a steadier gun platform with power changes.

The P-38 never had difficulties in taking off irrespective of prop rotation direction that I'm aware.

The aircraft that was unable to take off was the F-82 where the props rotated towards the centre line at the six o'clock position, that kept the centre section in a stalled condition because of the prop wash rotation. Fix was to swap engines so that rotation at the top of the prop (12 o'clock) was towards the centre line.

 

[Thumpalumpacus]

From my reading with the P-47, compressibility would cause the stick to feel like it was in concrete. It was unmovable until the airplane got into thicker air causing the Mach number to decrease. Then the pilot could regain control.

Was it related to the wave-propagation problems of the P-38, or was this caused by something else?