Malcolm Hood Installations for P-51B/C

[drgondog]

RAF Warton became the primary Air Depot (2) for B-24 and P-51. Each Fighter Group in the 8th and 9th Air Force had an on base Service Squadron/Group capable of implementing tech orders and significant repairs.

I have heard that the Malcolm Hood required between 85 and 135 hours to install and I am unclear where the primary installation took place.. conceivably it could have also been modified at 1AD Burtonwood which had responsibility for B-17 and P-47... RAF Warton or each local Service Group - I suspect tooling required so I suspect centralized process in which the Mustang was flown to a specific location, modified and returned to the combat unit. Ditto the first 250+ 85 gallon fuselage tanks for the P-51B-1, -5-NA and P-51C-1NT that arrived without them.

Can anyone shed light on this subject? BTW, according to The Mustang Story by Ken Delve (pg 35), the NAA engineers in UK in 1942 designed the Hood for the Mustang IA AG618 and Malcolm tweaked it for the blown hood and manufactured the canopies. The RAF modified very few Mustang I and IA but performed the modification on all Mustang III and IIIA at RAF Henlow before inserting them into combat ops, whereas the 8th AF typically received their P-51B/C's with the birdcage canopy - then had them modified.

[Graham Boak]

I find it amazing that NA with no experience in blown canopies are described as the designers, and Malcom with all the experience just a subcontractor. It seems more likely that NA engineers were given the responsibility for the interface parts, making the whole thing a joint design.

[drgondog]

Originally Posted by Graham Boak

I find it amazing that NA with no experience in blown canopies are described as the designers, and Malcom with all the experience just a subcontractor. It seems more likely that NA engineers were given the responsibility for the interface parts, making the whole thing a joint design.

Graham - I concur with your initial reaction - but the AFDU report AFDU/3/20/33 dated 7 December 1942 is explicit. "This Hood has been designed by North American representatives in this country and fitted to this aircraft by RAF Henlow, and is merely an interim measure in order to ascertain the tactical advantages of having a sliding hood on Mustang aircraft."

In fact Malcolm was not even mentioned in the report - implying that they were not even a subcontractor?

Today they are made in the States by having a mold, heating a sheet of plexiglass, then hand forcing the malleable plastic over the Mold until cooling - all in approximately 25 seconds with significant failure rates. Trim and hardware follow the successful process, the with tools/jigs rails are installed for final mounting on the P-51B/C

It is conceivable that RAF technicians and engineers made a mold to conform to the Mustang outer dimensions but I agree your point that Malcolm should have been involved. The first one was on a Mustang IA, and there is no record of any more being made or installed until Mustang III FE120 was installed on January 30, 1944.

[SteveB]

Hi
I think this is a question that is unlikely to generate a definite answer.

Firstly I think the USAAF structure you are referring to is a “Base Air Depot” - Burtonwood was BAD 1 and Warton was BAD 2 (Langford Loch in Ireland was BAD 3). Secondly in British terminology AG618 was a Mustang I; the Mustang IA was the P-51 with 4x20mm cannon. It is perhaps worth making the point that in the RAF Allison Mustangs were fitted with recce cameras that projected through the rear cockpit glazing it seems likely that a sliding hood would not have worked very well in those circumstances although some RAF Tac/R a/c were fitted with the hood later in 1944.

In my view there is no indication of a direct link between the sliding hood that was fitted to AG618 and described in the AFDU report and the modification known as the “Malcolm hood”. The AFDU report describes the modification on AG618 as a “lash up” which suggests it was not something that was intended to go into production. The hood that we see on Mustang IIIs (P-51B/C) was designed by Mr Lobelle at Malcolms and was fitted and tested on Mustang IA FD473 in September 1943.

I can't confirm your figures for the man hours involved in the installation but it is clear that it was a serious undertaking which included cutting into the top longeron in the cockpit area. In the RAF the hoods were initially fitted by civilian working parties from Malcolms during the preparation of Mustangs for squadron use. The first installation for the RAF was made in January 1944 on FZ140 (FE120 is not a Mustang serial). There is no evidence in the RAF that the modification was made at squadron level. Production of hood modification sets was very slow to build and correspondence critical of delays can still be found in files in June 1944. Supplies of modification sets had to be shared between the two airforces.

Steve

[Graham Boak]

There's an implication there that the original design had the same external lines as the original, with a small allowance for sliding, in which case there'd be no need to involve Malcolm above any other canopy manufacturer. Whereas Malcolm was responsible for the production "blown hood".

It is best to be a little careful here, as Edgar Brooks has pointed out with regards to the Spitfire that the so-called "blown hood" on that fighter was not actually expanded by air pressure along modern lines but was moulded over a fixed bulged mould and removed vertically. Was this also true of the Mustang? I presume that your description above does apply the bulged variety. In which case the question is whether the current shapes match the wartime ones, or are they just "near enough"?

[drgondog]

First - than you both for your thoughtful replies. So far my current best source is Ken Delve's Mustang Story and is the source for the AFDU report, from which I posed the above quote referencing sliding hood and a/c number.

Steve - I was also confused regarding the reference of AG618 as a Mustang IA as my primary source (Gruenhagen) says AG345 to AG664 as Mustang I (NA-73), but reproduced the quote 'as is'.. There is no numerical range for the IA which encompasses "618' for the series FD. You are correct and the AFDU report as written can not properly identify the first sliding hood to a P-51-1/IA with "AG618". Having said that I have zero reliable reference to RAF a/c codes to NAA serial numbers so the process of sure identification is tenuous.

I did misread the memo from 3501 Servicing Unit regarding the installation on "FZ 120" (mistaking a blurry Z as an E) but it is equally not "FZ140". The memo clearly states that a four person civilian subcontract crew from Malcolm Ltd performed the work.

To your point that no work was performed at the squadron level (for RAF), I concur that so far I have seen only reference to RAF Granfield and RAF Henlow in connection with the Mustang III installation. There are vague references, but so far I have found no written documentation from either AAF Service Group or Squadron at each Mustang base to cite the Malcolm being installed at the airfield Service Group.

As to the phrase Blown Hood versus sliding hood. My terminology as you deduced Graham, refers to the shape, not the process. Having said that there is no way to deduce from the AFDU memo whether it was formed by the methods employed for "Drape Moulding" as described by Edgar Brooks, at Maidenhead/on White Waltham or by another as yet unknow method. For certain it was not a modified Spitfire or Typhoon canopy as their respective dimensional widths are too small for a Mustang.

The primary source for Warbird community is Aerotraders and apparently they build them the same way - i.e Plexiglass sheet in a frame, heat to point of melt, remove (quickly) the frame and six people drape it over the mold.

Steve - I believe the short supply was more critical to RAF than AAF as the US combat units performed the mod only when both kits and operational rhythm permitted the P-51 to be sent (either to BAD or on-base SG) whereas my sources cite the RAF installation as mandatory and preliminary to dispatching to operational squadrons.

I will solcit some insight from Aldon Freguson to see if he can shed some light on this subject.

Thank you both

Bill

[Graham Boak]

FD473 is listed in Air Britain' serial book as having been the Malcolm Hood trials aircraft, but seeing no other service.
AG618 is recorded as having two spells with the AFDU, sandwiching 1483 (Bombing Gunnery Flt, but went on to serve as a combat aircraft. This suggests it did not have a non-standard canopy - or perhaps it was just retrofitted later?

[drgondog]

Originally Posted by Graham Boak

FD473 is listed in Air Britain' serial book as having been the Malcolm Hood trials aircraft, but seeing no other service.
AG618 is recorded as having two spells with the AFDU, sandwiching 1483 (Bombing Gunnery Flt, but went on to serve as a combat aircraft. This suggests it did not have a non-standard canopy - or perhaps it was just retrofitted later?

Hard to say Graham but given that the AFDU report was dated 7 December 1942 it could have also been restored to factory configuration or left "as is".