Mustang Numbers

[Geoffrey Sinclair]

Additional information welcome.

 

[drgondog]

Under tab 'designations'

P-51B-1-NA 43-12102 same as P-51B-1-NA save addition of Cockpit Enclosure, Sliding.
P-51D-NA 42-106539 same as P-51B-1-NA 43-12102 save addition of new six gun wing. Modified from P-51B-1-NA Spare Fuselage.
P-51D-1-NT 42-106540 same as P-51B-1-NA 43-12102 save addition of new six gun wing and 55gal fuselage tank.

All three were modified side by side in Experimental Department between July 1943 and December 1943. The MCR for the Cockpit Enclosure, Sliding in NA-102 Specificaton was C-258-2. The corresponding MCR for NA-106 Specification was C-258-1 and -3.

The serial numbers were assigned on September 11,1943 almost three months before P-51B-10 #1 first flew. Had the AAF accepted the P-51D as suitable with 55gal tank, there would not have been P-51D-10-NA 're-starting' at 42-106541. Would have been P-51D-1-NA #3 & P-51D-1-NT replacing P-51C-5-NT late in the block.

The P-51D-1-NT 42-106540 had an approved ECO (Nov 1943) to move the wing attach 4 " (to the Rear) from FS 104 and FS 143 to pemit 85 gal tank and added rear cg of two extra 50 cal plus 600 rnds more ammo - but flight tests at Eglin for 51B-1 modified with 85 gal fuselage tank showed the aft cg location 'livable' with caveats. Calculations regarding effect of moving wing aft without associated movement of the empennage would have meant an unacceptable production delay.

Moving the wing Forward was impossible. That would have made the aft cg problem even worse.

The P-51D-5 under NA-109 received funding from NA-106 which was closed in December 1943.

 

[drgondog]

I would also contrast the 'official NAA' descriptions from O Contract Report with the 1945 AAF contained in your spreadsheet. Most of the descriptions you have in that section are correct but some data mismatch are glaring.

The A-36 was similar to XP-51 save addition of dive brakes, changed armament to two 50 cal guns in each wing, addition of fuel plumbing for external fuel tanks, racks installed for either 75gal fuel tank or up to 500 pound bombs'.

The P-51A was similar to A-36 save deletion of dive brakes and cowl guns.

For example the description for XP-51F as 'similar to XP-51B except lighter in weight' is probably the worst of the batch. Simply, there was nothing similar to XP-51B. Not a single part, not a common fuselage or empennage or wing datum/dimension. The XP-51F was 'a completely new model only similar in appearance to P-51D, designed to slighly lower design loads to reduce weight'.

The part in the B-5-NA regarding minor changes should be stricken and replaced with "mid block incorporated pressurization for combat tanks, changes to radio bay to accmmodate field installation of 85 gallon tank' - should probably be added.

The P-51D-5-NA incorporated the dorsal fin and reverse rudder boost tab at #651. ALL D-10 were so equipped at Inglewood for delivery. They also were released in first block with 1650-3 engines, same as B-1, B-5 and B-10.

The P-51D as noted was 'similar to P-51B-1-NA save six gun wing, guns installed vertically, sliding canopy and removed roll over structure'. P-51D-1 provided with 55gal fuselage tank. To clarify, they were built with P-51B-1 spare fuselage which had no carb screen.

The P-51H was a new design with greater fuselage length, wing moved further aft of firewall, different canopy extended aft lower cowl, different oil cooling arrangement, larger empennage, greater fuel capacity in left wing and added fuselage tank, six gun wing vs four of XP-51F/G & J".

etc, etc.

That said, you put a lot of work in this spreadsheet.

 

[Geoffrey Sinclair]

Thanks for the information, notes incorporated, the USAAF tends to defer to North American documents about the changes and it seem clear why,

That said, you put a lot of work in this spreadsheet.

The real work is finding the original documents, the rest is straightforward.

 

[drgondog]

Thanks for the information, notes incorporated, the USAAF tends to defer to North American documents about the changes and it seem clear why,


The real work is finding the original documents, the rest is straightforward.

The Weekly Service Bulletins on the topic of features by new model are a treasure trove because they state the production break serial number (AAF). For example on the B-5 it will point out 43-6713 as #1 for combat tank pressurization and IIRC a production vaccum pump installation to feed from thetanks.

P-51D and D-1 require digging deep into AAF/NAA telex exchanges and project logs to establish the chronology of the Cockpit Enclosure, Sliding, the P-51B-1 spare fuselagee, etc as well as the Material Change Request numbers for respective model specification (106 for D, D-1) and 102 for B-1.

Ditto the evolving discussion of 85 gal to 55 gal to installing only on D-1, then the cancellation of NA-106 and D, D-1 as production articles #1 and #2 when AAF decreed only 85 gal tanks after Jan 1 for all delivered Mustangs.

 

[drgondog]

As an additional note, to those that believe that the D and D-1 were crafted from NA-104/P-51B-10 based on serial number beginning at 42-106539, they can't expain why neither had a fuse tank after the new bubble canopy was installed - when all prior B-10's back to 7113 delivered from December had all the fuse tank modifications and tank installed two months After 42-106539 was completed in September.

The issue wasn't available volume behind seat - it was a further movement of CG with two extra 50 cal + 600rnds more ammo, even farther back than B/C fully loaded.

That said, after November 1943 testing at Eglin, everybody decided that it was livable with caution until at fuse tank fuel burned down to 40-50 gallons.

 

[Geoffrey Sinclair]

Update, comments incorporated, Australian production added.

 

[drgondog]

Update, comments incorporated, Australian production added.

Nice work. I have a couple of addt'l data points for you.

FF
73X October 26, 1940
NA-73 April 3, 1941
XP-51 May 20, 1941
P-51 May 1942
P-51A Feb 1942
P-51B May 5, 1943
P-51C Aug 1943
P-51D-1 Nov 17, 1943
P-51D-5 Jan 27, 1944

I have to go look for specific dates on the others.. Interesting (to me) that the airframe, sans engine for P-51B-1 #1 was completed one month after the P-51A #1 was completed - but not flyable until Packard started delivery of the 1650-3s. At that moment in time the A-36, P-51A and P-51B were all on the line at Inglewood.

 

[gruad]

IIRC there were 2 simultaneous conversions to Merlin done independently.

Is this correct mustang experts please?

 

[drgondog]

IIRC there were 2 simultaneous conversions to Merlin done independently.

Is this correct mustang experts please?

yes. P-51-NA 41-37352 and 41-37421 converted but not quite simultaneously. 352 was converted 1st, then 421 next.

 

[drgondog]

Update, comments incorporated, Australian production added.

More updates
73X October 26, 1940
NA-73 April 3, 1941
XP-51 May 20, 1941
P-51-NA May 31, 1942
A-36 September 21, 1942
XP-51B#1 Nov 30, 1942
P-51A February 4, 1943
XP_51B#2 March 9, 1943
P-51B May 5, 1943
P-51C Aug 1943
P-51D-1 Nov 17, 1943
P-51D-5 Jan 27, 1944
XP-51F Feb 14, 1944
XP-51G Aug 12, 1944
XP-51J April 23-1945
XP-82 June 16, 1945

 

[ColFord]

IIRC there were 2 simultaneous conversions to Merlin done independently.

Is this correct mustang experts please?

Would you be thinking of the conversion of five Mustang Mk I airframes conducted by Rolls-Royce in the UK to create the Mustang X, which proved the basic performance increase predicted at higher altitudes by fitting a two-stage Merlin into the Mustang airframe? The first flight by one of the R-R modified Mustang Mk I in Mustang X configuration, being AL-975-G was on 13 October 1942.

In the US, NAA was pursuing their own program utilising two P-51 (no suffix) Mustang Mk IA airframes, with the first of their conversions flying on 30 November 1942, pointing the way for the development of the Packard Merlin engined P-51B/C.

So basically the two programs were running in parallel.

 

[drgondog]

Would you be thinking of the conversion of five Mustang Mk I airframes conducted by Rolls-Royce in the UK to create the Mustang X, which proved the basic performance increase predicted at higher altitudes by fitting a two-stage Merlin into the Mustang airframe? The first flight by one of the R-R modified Mustang Mk I in Mustang X configuration, being AL-975-G was on 13 October 1942.

In the US, NAA was pursuing their own program utilising two P-51 (no suffix) Mustang Mk IA airframes, with the first of their conversions flying on 30 November 1942, pointing the way for the development of the Packard Merlin engined P-51B/C.

So basically the two programs were running in parallel.

Better answer, Colin. I had a little myopia re:NAA

NAA was 15-30 days behind R-R depending upon how one defines 'start'.

 

[gruad]

Would you be thinking of the conversion of five Mustang Mk I airframes conducted by Rolls-Royce in the UK to create the Mustang X, which proved the basic performance increase predicted at higher altitudes by fitting a two-stage Merlin into the Mustang airframe? The first flight by one of the R-R modified Mustang Mk I in Mustang X configuration, being AL-975-G was on 13 October 1942.

In the US, NAA was pursuing their own program utilising two P-51 (no suffix) Mustang Mk IA airframes, with the first of their conversions flying on 30 November 1942, pointing the way for the development of the Packard Merlin engined P-51B/C.

So basically the two programs were running in parallel.

It's a shame the UK never realized that the mustang was a much superior airplane than the spitfire with regards to the requirement of the war at that point which was to go on the offensive

Could that have been mustangs built in the UK under license?

Eventually the spitfire was applied against the axis but that required the invasion to happen first and for them to operate from makeshift airfields

 

[GregP]

If the British had the capacity to build more airplanes, they would have built more Spitfires or other British-designed aircraft. The only reason they flew any U.S. aircraft at all was lack of sufficient production capacity to support the war. So, asking for them to built a new type would be a bit out of the park. They already couldn't produce enough of what they actually wanted to fight with the number of aircraft required.

In peacetime, I'm SURE they could have built the P-51. The only question in my mind is, would they have wanted to do so? I doubt the answer would be yes.

 

[gruad]

The spitfire was great at what it did ie an interceptor.

It always seemed a shame to me that the bombers went on the offensive and the fighters seemed to stay at home defending much less contested airspace.

I suppose eventually bomber command got the escorts in that at night. Intruder mosquitoes accompanied the bomber stream and during the day I believe the Americans gave cover.

Does anyone have an idea of how the late RAF daylight raids were organized. I'm pretty sure they were escorted but by who and how I don't know. And in addition I don't know whether they were formation bombing or not.

Any responses would be appreciated

 

[ColFord]

The UK/RAF certainly wanted more Mustangs, both varieties, Allison engined for low level Tactical Reconnaissance and low to medium level work; and Merlin engined for the medium to high altitude work including bomber escort and long range interdiction. UK looked at proposals for NAA to send Mustang airframes without engines, with R-R Merlins to be fitted after arrival in the UK. That however was not feasible as what R-R Merlin production capacity there already was in the UK was committed to powering other types already in production and in demand by the RAF. To free up UK made R-R Merlins for Mustangs meant some other type would miss out. There was also just the simple fact that the support and supply services in the UK were overstretched with lots of competing priorities for manpower, resources and materials coming in from other Allied nations.

RAF had been using its Allison engined Mustangs for long range interdiction - 'Rangers' and 'Rhubarbs' conducted at low lever over occupied France, Belgium and the Netherlands, extending into western Germany in late October 1942. They had also experimented with Allison engined Mustangs providing escort to low level bombers of 2 Group from September 1942 into early 1943. Allison engined Mustangs were also conducting intruder operations against Luftwaffe airfields in the Netherlands, Belgium and northern France, as far west as Paris up until November 1943. A number of those operations were conducted in the late afternoon or approaching dusk, with the aim of catching Luftwaffe night fighters doing their flight tests for that night's operations against RAF bombers, or as they were taking off to position themselves for that nights work.

When the RAF commenced its daylight raids in mid 1944, the early ones were primarily around the Normandy beachhead, so could call on RAF and USAAF escort fighters based in the UK and also on the ALGs in Normandy. When the RAF commenced their daylight raids against targets further afield in late 1944 onwards, the RAF used a 'shuttle' escort arrangement, with Spitfires based in the UK with long range tanks covering the bombers part of the way, then RAF Mustangs taking over the escort on the more distant part of the raid. Sometimes, they would stage Spitfires based in the UK either out or back through ALGs on the continent to further extend their range. RAF also provided UK based Spitfires as escorts for some of the USAAF daylight raids, providing escort for the initial section out to the 'enemy coast', and then meeting them again as they exited the 'enemy coast' and made their way back to the UK.

If you want a good book about the development of the North American Mustang including its operational use up until around June 1944, I can commend:

drgondog/bill who responded to you earlier in this thread is the author and he is working on a follow on volume that will cover P-51 development from June 1944 onwards.

 

[gruad]

RAF had been using its Allison engined Mustangs for long range interdiction - 'Rangers' and 'Rhubarbs' conducted at low lever over occupied France, Belgium and the Netherlands, extending into western Germany in late October 1942. They had also experimented with Allison engined Mustangs providing escort to low level bombers of 2 Group from September 1942 into early 1943. Allison engined Mustangs were also conducting intruder operations against Luftwaffe airfields in the Netherlands, Belgium and northern France, as far west as Paris up until November 1943. A number of those operations were conducted in the late afternoon or approaching dusk, with the aim of catching Luftwaffe night fighters doing their flight tests for that night's operations against RAF bombers, or as they were taking off to position themselves for that nights work.

Thanks ColFord. Didn't know about this.Just assumed Alison engine planes were used against troop emplacements.

Interestingly IIRC a Mustang takes out the Tiger tank at the end of Saving Private Ryan so that's maybe where I got the idea from....

 

[Geoffrey Sinclair]

There were differences in standards between the US and British manufacturing systems at the most fundamental levels, like screw threads and alloy compositions, there are probably Australian and Canadian documents about how they coped when building both US and British designs, like what items they ended up importing. As noted the RAF tried to obtain Mustang airframes, there is also an Australian document noting the 100 Mustang kits on order were being held up because of a British request for 2,000 kits. License production would be a big project and would need something to go out of UK production, in addition the P-51 was built to a higher standard of finish to maximise the wing laminar flow.

The divergence between the USAAF and USN equipment was addressed by the AN (Army Navy) standards during the war and there were attempts to come up with common standards across allied production.

It's a shame the UK never realized that the mustang was a much superior airplane than the spitfire with regards to the requirement of the war at that point which was to go on the offensive

What is the definition of "of the war at that point"?

In July and August 1943 the Luftwaffe received a series of significant wake up calls, in date order,

1) On 5 July the Kursk offensive begins, for the first time in the east the Luftwaffe is unable to secure air superiority where it wants it, the Red Air Force is able to intervene effectively. The air force needs to become bigger, given the Red Air Force largely ignores its opposite number the Luftwaffe can still usually operate.

2) 10 July the allied invasion of Sicily, in the air fighting before and during the invasion the Luftwaffe discovers the more aircraft it commits the higher the casualties without changing the overall situation. The air force needs to become much bigger or leave.

3) 27 July the firestorm at Hamburg.

4) 17 August the strikes on Schweinfurt and Peenemunde.

The next day the Luftwaffe chief of staff committed suicide. Starting in July, after the failures of the Kursk and Sicily operations and with such pressure on the home defences the Luftwaffe focus shifted to defending Germany which in the west translated to fewer Luftwaffe day fighters near the front lines. That still left the requirement for fighter defences of allied areas, giving the long range efforts the benefit of secure bases, plus eventual front line support of Operation Overlord.

Suddenly, overnight, things had changed, way faster than the weapons production system could cope, think of all those allied fighter bombers in the 2nd TAF and 9th AF carrying superchargers and even oxygen systems they rarely to never used given their normal operating altitudes. For the war the 9th AF reports 114 fighter sorties non effective due to oxygen problems, out of 5,331 aborts due to mechanical problems, while crew illness etc. caused 402 aborts. The ratio of long range bomber to fighter units and their equipment in 1943/44 had been set by decisions taken in 1941/42. It was not until sometime in 1944 the allies considered they had the world wide front line fighter force they needed, quality and quantity.

As predicted there were major air fights around the Normandy Bridgehead, for RAF Fighter command June and July 1944 are in the top 5 months for kill claims but the major drop in Luftwaffe quality (fighters) and quality and numbers (bombers) in the first months of 1944 plus the size of the allied air forces ensured the Luftwaffe had little impact.

After years of everyone wants the Spitfire, from maybe as early as 1939, and particular the latest versions, which meant decisions that reduced production were a big issue, it changed to everyone wants the Mustang which remained in short supply through 1944. With something as big as an air force you can usually find the early champion and the die hard opponent, so what the Air Force thought is a sort of average along with the ideas of key people, the USAAF thinking into 1943 had the P-47 as the main fighter, the P-51 going to the 9th AF for example. While US allies were receiving plenty of P-39, P-40 and P-51 all through 1943, the US only allocated 3 P-47 to the USSR in September and 2 to the UK in December. It was in January 1944 regular P-47 deliveries began for non US users.

Into 1943 the RAF was expecting to receive a very large proportion of P-51 production, something that changed during 1943 to early 1944. One end 1943 document has 2,269 US to 600 RAF P-51 allocations for the year, and I believe the allocation ratio was higher as of mid 1943, the slippage in production schedules meant 1,216 US and 439 RAF deliveries. In January 1943 North American had an order for 310 P-51A to be followed by a planned 3,340 Merlin versions, Republic was finishing off the P-47C order and was starting on the planned 8,593 P-47D. Using the contract dates another 500 P-51 were added in February, and as of mid 1943 9,719 P-47 of all types had been ordered to 7,687 P-51, plus 620 Mustang on British orders. Shows the shift in USAAF thinking.

As many, many discussions have shown the Spitfire VIII had similar range to the mid 1943 P-47 and if it had been fitted with a rear fuselage fuel tank it would have matched the early 1944 P-47 range, the 8th AF P-47 units saw plenty of combat into the first half of 1944. Starting mid 1943 the Luftwaffe largely pulled out of Spitfire range, the mark VII had just been introduced, with a percentage increase of internal fuel from the earlier versions similar to that done when the P-51 was fitted with the fuselage fuel tank but the requirement to find the Luftwaffe became just about double the original tankage and take the production hit to change the main factory over to the new version, or use the P-51.

Bomber Command day raids on Germany 1944/45 were mostly confined to the Ruhr and other targets near the border, they were not deep penetration, partly as the haze over the Ruhr made it hard for the 8th AF bombers to hit targets there and partly due to the available fighter escorts. As noted Spitfires based in Britain did a lot of the escorting, helped by France and Belgium being friendly territory. Formations were loose, way loose by US standards, permitting individual visual bombing and while non visual bombing was done by formation the formation sizes tended to be smaller than the US ones. Given the amount and accuracy of Ruhr flak and the availability and accuracy of aides like GH the RAF seems to have preferred cloudy days for those raids.

 

[EwenS]

The spitfire was great at what it did ie an interceptor.

It always seemed a shame to me that the bombers went on the offensive and the fighters seemed to stay at home defending much less contested airspace.

I suppose eventually bomber command got the escorts in that at night. Intruder mosquitoes accompanied the bomber stream and during the day I believe the Americans gave cover.

Does anyone have an idea of how the late RAF daylight raids were organized. I'm pretty sure they were escorted but by who and how I don't know. And in addition I don't know whether they were formation bombing or not.

Any responses would be appreciated

The attached article sets out details of the RAF Bomber Command daylight bombing campaign from the end of Aug 1944 to the end of the war.

In terms of RAF Packard Merlin Mustang squadrons, there were 7 by the end of April 1944 of which 6 were in 2nd TAF supporting the Normandy invasion. At the beginning of July, 3 squadrons were transferred to ADGB to combat the V1 with the other 3 following at the end of Sept, at which point all were moved to East Anglia as bomber escorts. From Sept onwards more squadrons began to convert to the Mustang III/IV or form on the type, at a rate of about 1 per month all the way to the end of the war in Europe as more aircraft became available. The number of operational squadrons peaked at 16 in April 1945 with a further unit in the process of converting during May.

Mustang III (P-51B/C) formed the main equipment with Mustang IV/IVa (P-51D/K) arriving on at least some of the squadrons from Jan 1945.

At the beginning of Nov 1944 1 squadron (2 from Feb 1945 following the losses suffered by the Dallachy Strike Wing on 9 Feb 'Black Friday') were sent north to Peterhead in Scotland to cover the activities of the Coastal Command Dallachy & Banff Strike Wings operating off the Norwegian Coast which were meeting increasing aerial opposition from the Luftwaffe.

Remaining Spitfire squadrons in ADGB/Fighter Command continued their bomber escort activities for the RAF as they had been doing for the USAAF 8th AF.