P-47M question

[MiloMorai]

I saw it stated on another board that when the P-47M arrived in GB it did 2-3 months of operational service trials before being cleared to operational combat status.

Has anyone come across USAAF or other documentation or seen this before. I find it strange as have not seen this for any other a/c type when the unit upgraded to a newer model of the a/c they were currently flying. I can see it for an altogether new type of a/c.

[TUXC]

I think they had some issues with the new engine/turbocharger setup.

[Widewing]

Those P-47Ms suffered a loss of power at altitude, and suffered from over-cooling as well.

Technical Services at Bovington suspected that the R-2800-57 engines were suffering the same issues as the earlier R-2800-21 engines delivered in the first P-47Cs to arrive in England.

Inspection revealed that they were generally correct. These problems included;

Cracked insulation on ignition leads.
Improperly sealed magnetos.
Improper cylinder baffling.
Improperly adjusted cam setting on the throttle-turbo linkage.

Note that the P-47Ms flew over 300 individual sorties before the 56th became so frustrated that the planes were grounded until the problems were resolved. By late March of 1945, all of the P-47s were repaired/re-rigged and the 56th began test flying every one of them. Within two weeks they were back in combat again.

My regards,

Widewing

[Entr0py]

Widewing beat me to it, The Mighty Eighth War Manual has all that info and more concerning the principal aircraft used by the Eighth Air Force. It's a valuable resource for anyone. Copies can be had for dirt cheap, I got mine for like 2 bux. It's well worth picking up.

[Wolfala]

Originally posted by Widewing
Those P-47Ms suffered a loss of power at altitude, and suffered from over-cooling as well.

Technical Services at Bovington suspected that the R-2800-57 engines were suffering the same issues as the earlier R-2800-21 engines delivered in the first P-47Cs to arrive in England.

Inspection revealed that they were generally correct. These problems included;

Cracked insulation on ignition leads.
Improperly sealed magnetos.
Improper cylinder baffling.
Improperly adjusted cam setting on the throttle-turbo linkage.

Note that the P-47Ms flew over 300 individual sorties before the 56th became so frustrated that the planes were grounded until the problems were resolved. By late March of 1945, all of the P-47s were repaired/re-rigged and the 56th began test flying every one of them. Within two weeks they were back in combat again.

My regards,

Widewing

I thought the M's used the 2800-C? What was different about the ignition setup in the M then the N?

[Widewing]

Originally posted by Wolfala
I thought the M's used the 2800-C? What was different about the ignition setup in the M then the N?

The R-2800-57 is a C series engine. It was installed in the XP-47J, YP-47Ms, P-47M-1, XP-47N and the P-47N-1 block.

Also cited as a contributor to the P-47M troubles was the fact that the engines were not properly preserved for trans-Atlantic shipment. This resulted in engine failures due to internal fretting type corrosion. The problems with the cam setting on the throttle-turbo linkage was due to improper rigging when the aircraft were assembled and rigged in Britain. The cam settings were different on the P-47M (CH-5 turbo) than that of the late P-47D series with C-23 turbos. Col. Cass Hough reported that they were rigged for the C-23, which caused a substantial loss of power above 20,000 feet.

Republic flight tested every P-47M to 35,000 feet prior to delivery and acceptance by the USAAF. They left Farmingdale correctly rigged and without ignition or engine problems. The AAF disassembled and prepped them for shipment.

My regards,

Widewing

[Wolfala]

Wouldn't it have been easier to ferry them rather then **** them up by taking them apart and having to re-rig when they got to Europe? Just using 300 gal ferry's via Novascotia, Greenland, Iceland, Ireland, etc.

[Mike Williams]

I’ve not studied the operational history of the P-47M in any depth, however, here are a few documents relating to the P-47M’s engine difficulties that I found interesting and informative:

P-47M Engine Failures in the United Kingdom, 20 March 1945

P-47M Difficulties, 10 April 1945

Air Technical Service Command, May 9 1945

Mike

[Captain Virgil Hilts]

Originally posted by Wolfala
Wouldn't it have been easier to ferry them rather then **** them up by taking them apart and having to re-rig when they got to Europe? Just using 300 gal ferry's via Novascotia, Greenland, Iceland, Ireland, etc.

Not a good idea. It was called "Operation Bolero". All that has to happen is a little bad weather, a minor navigational error, or any mechanical problems, and you have a good chance of a major disaster. The ferry mission that "Glacier Girl" was in is a prime example. They lost six P-38's and two B-17's in one mission. And easily could have lost every man in them.

[skaltura]

Widewing wrote "...suffered from over-cooling as well." Do you have info on the CHTs encountered which were considered "overcooled"? From various accounts it is quite clear that many pilots considered CHT values well above manual limits (120 deg C) as "overcooling", let alone compared to CHT figs P&W considered safe and unharmful (see P&W rep statement in the JFC report).

[Widewing]

Originally posted by skaltura
Widewing wrote "...suffered from over-cooling as well." Do you have info on the CHTs encountered which were considered "overcooled"? From various accounts it is quite clear that many pilots considered CHT values well above manual limits (120 deg C) as "overcooling", let alone compared to CHT figs P&W considered safe and unharmful (see P&W rep statement in the JFC report).

I haven't seen anything that defines the specific CHT, but the problem occurred during cruise settings. The issue was resolved by adding a baffle at the cowling outlets to reduce airflow when cowl flaps were fully closed. This also was reported to have created a more uniform air flow across the cylinder heads.

My experience with the R-2800 was that over-cooling could become an issue in a protracted, power-off descent. We kept a close eye on CHT during descents in our C-131s.

My regards,

Widewing

[skaltura]

What were the CHTs you encountered during those descents? When testing the XF8B-1, the lowest CHT the test pilots encountered was 130 deg C and that was described as "overcooling" despite being above manual minimum recommended of 120 deg C and over 100 deg C more than the temperature given as one giving satisfactory operation by the factory rep mr. Debruyn during the JFC in response to claims of F7F overcooling, based on arctic tests.

[Widewing]

Originally posted by Wolfala
Wouldn't it have been easier to ferry them rather then **** them up by taking them apart and having to re-rig when they got to Europe? Just using 300 gal ferry's via Novascotia, Greenland, Iceland, Ireland, etc.

Most P-47s arrived in Britain like this.



My regards,

Widewing

[Stoney74]

Did I read that the 318th FG ferried the P-47N's to Ie Shima?