What is a P-51M?

[KiwiZac]

Hi all,
Lately this question has been confusing the heck out of me. The Production section of the main Mustang page on Wikipedia says the P-51M is a variant of the D:

Same as P-51D-25-NT and P-51D-30-NT, but with the non-water injected V-1650-9A engine for low-altitude operations and sharing the cuffless Hamilton Standard propeller.[136]​[137]​ It was intended to enter full production at Dallas, but the contract was later cancelled.

On the North American P-51 Mustang variants page on Wiki this appears in the P-51H section (my italics):

The P-51H was designed to complement the P-47N as the primary aircraft for the invasion of Japan, with 2,000 ordered to be manufactured at Inglewood. Production was just gathering speed with 555 delivered when the war ended. Additional orders, already on the books, were canceled. With the cutback in production, the variants of the P-51H with different versions of the Merlin engine were produced in either limited numbers or terminated. These included the P-51L, similar to the P-51H but utilizing the 2,270 hp (1,690 kW) V-1650-11 engine, which was never built; and its Dallas-built version, the P-51M, or NA-124, which used the V-1650-9A engine lacking water injection and therefore rated for lower maximum power, of which one was built out of the original 1629 ordered, serial number 45-11743.

Yet, in the Summary of P-51 variants, we're back to the idea M = D variant:

P-51M (NA-124)
The P-51M-1-NT was based on the P-51D-30-NA/NT, but utilized the V-1650-9A engine lacking water injection and therefore rated for lower maximum power than the -7. One was completed out of the original 1629 ordered, AAF Serial Number 45-11743.[75]​

On the Secret Projects forum writer Steve Pace posted a photo of a Mustang serialled 45-11742 and said it was an M. He later contacted Boeing for info and got this reply:

Steve,
That photo is the last P-51D built at Dallas, according to our NAA records, 45-11742 was the last P-51D - that photo was taken around Aug. 1945.

The P-51M was 45-11743. Have not been able to find any photos or other information on the illusive[sic] P-51M, the only notes we have on the P-51M is that it was used to test the Merlin V-1650-9A – there are unfortunately no records of any flight tests.

I know there are a lot of stories about the P-51M but I have not been able to substantiate any of them.

Michael Lombardi Corporate Historian - The Boeing Company

Steve ended up with more research that suggests the P-51M was indeed a re-engined D and not a variant of the H.

So which is right? Can the M = H concept be put out to pasture?

 

[fubar57]

This according to Joe Bauger's site regarding 45-11742

"11742 (18th FBG, 39th FIS) hit by ground fire and crash landed at liaison strip Oct 18, 1951."

EDIT: Just noticed below 45-11742.
45-11743 North American P-51M Mustang. MSN 124-48496

Time to call in drgondog

 

[drgondog]

This according to Joe Bauger's site regarding 45-11742

"11742 (18th FBG, 39th FIS) hit by ground fire and crash landed at liaison strip Oct 18, 1951."

EDIT: Just noticed below 45-11742.
45-11743 North American P-51M Mustang. MSN 124-48496

Time to call in drgondog

Sharp eyes. The end of the P-51D-30-NT was 45-11742. The P-51M (743 #1 and P-51D-30-N was #1001) and was the last -30 and converted with the different engine from 1650-7, and scrapped), ten re-coded at P-51M-NT. The sole significant difference was the introduction of the 1650-9A engine without Water Injection of the 1650-9 in the P-51H.

 

[wuzak]

I found this quote from the OP interesting:

Same as P-51D-25-NT and P-51D-30-NT, but with the non-water injected V-1650-9A engine for low-altitude operations and sharing the cuffless Hamilton Standard propeller.[136][137] It was intended to enter full production at Dallas, but the contract was later cancelled.

I would have thought the -9A without ADI would be even less of a low altitude engine than the -9 with ADI.

The extra performance from the ADI comes from higher boost (90inHg MAP), which has a lower critical altitude than lower boost levels.

 

[Geoffrey Sinclair]

Army Aircraft Model Designations 12th Edition, 1 June 1946
P-51L-NA, essentially the same as the P-51H except V-1650-11 engine (P-51H V-1650-9)
P-51M-NT (M & M-1) Essentially same as the P-51H except V-1650-9A engine. TP-51M-1 Trainer versions. All cancelled except one P-51M, which was accepted in June 1945 (Dallas ended production in August).

The accompanying line drawings have one set labelled P-51D&K, one labelled P-51H and one labelled M, XP_51F,G,J

 

[drgondog]

I found this quote from the OP interesting:



I would have thought the -9A without ADI would be even less of a low altitude engine than the -9 with ADI.

The extra performance from the ADI comes from higher boost (90inHg MAP), which has a lower critical altitude than lower boost levels.

I haven't loked at 9A power curves (Bench) in awhile - but agree with you. The Ram should be no different, the 9A was slightly heavier than the -3 (and -7) but stronger - basically different pressure carb and no WI when comparing between 9 and 9A.

Army Aircraft Model Designations 12th Edition, 1 June 1946
P-51L-NA, essentially the same as the P-51H except V-1650-11 engine (P-51H V-1650-9)
P-51M-NT (M & M-1) Essentially same as the P-51H except V-1650-9A engine. TP-51M-1 Trainer versions. All cancelled except one P-51M, which was accepted in June 1945 (Dallas ended production in August).

The accompanying line drawings have one set labelled P-51D&K, one labelled P-51H and one labelled M, XP_51F,G,J

From NAA , Airframe Contract Records, General Contract Administration "O" Reports dated 1-7-44, and per revision 8/45, the NA-124 charge number was issued and completed as NAA Factory serial no's 124-4426 to 44845, Customer Serial No. 44-84246 to 849 and 45-11343 to 45-11743 at P-51D-30-NT. Under Description
"(Texas) Same as NA-109. Contract reduced from 2000 to 1001. Last airplane powered by Packard V-1650-9A eng. and designated P-51M."

Otherwise PURE P-51D-30-NT airframe save some mods to Powerplant section forward of FS 99.

Same Record details for O report dated 7-27-56.and revision dated 3-20-57.

Note for your edification.

ALL NA-105 (105A and 105B) for XP-51F/G/J and ALL NA-126 (P-51H) tooling resided at Inglewwod with capacity to meet contract NA-117 then NA-126 as P-51H. Zero P-51H expansion was contemplated to be established at Dallas Plant. Ergo. P-51M, built in Dallas, was last in P-51D-30-NT line (cancelled at Ship no. 1001) and 'one of one' P-51D-30-NT airframe modififed with 1650-9A.

Further, The XP-82 and P-51H replaced the NA-122 P-51D-30-NA as All SUBSEQUENT P-51D airframes were assigned to Dallas in mid 1945.

Further, The Serial no. Blocks assigned to P-51H were 44-64160 through 44-64714. EDIT was 44--64169 (typo) - now 44-64714.

Further, for future reference, I would draw you to Gruenhagen and Wagner and Lowell Ford and myself - all having access to original NAA source documents on this and other matters.

 

[wuzak]

I haven't loked at 9A power curves (Bench) in awhile - but agree with you. The Ram should be no different, the 9A was slightly heavier than the -3 (and -7) but stronger - basically different pressure carb and no WI when comparing between 9 and 9A.

The -9/-9A having higher supercharger gear ratios (same as -3 IIRC) should have higher critical altitudes than the -7 at the same boost levels.

 

[drgondog]

Army Aircraft Model Designations 12th Edition, 1 June 1946
P-51L-NA, essentially the same as the P-51H except V-1650-11 engine (P-51H V-1650-9)
P-51M-NT (M & M-1) Essentially same as the P-51H except V-1650-9A engine. TP-51M-1 Trainer versions. All cancelled except one P-51M, which was accepted in June 1945 (Dallas ended production in August).

The accompanying line drawings have one set labelled P-51D&K, one labelled P-51H and one labelled M, XP_51F,G,J

Nope. P-51M-NT was #1001 (and last) of the NA-124 contract. It was pulled into Dallas Experimental Dept and firewall from FS 99 forward was slightly modified to accept the 1650-9A in lieu of the 1650-7 engine. There were zero NA-126 P-51H built or early assembled at Dallas plant. ALL LW Mustang tooling resided in Inglewood.

Refer to original NAA Contractor Reports for clarity.

 

[Geoffrey Sinclair]

From NAA , Airframe Contract Records, General Contract Administration "O" Reports dated 1-7-44, and per revision 8/45, the NA-124 contract was issued and completed as NAA Factory serial no's 124-4426 to 44845, Customer Serial No. 44-84246 to 849 and 45-11343 to 45-11743 at P-51D-30-NT.

Try the Index of AF Serial Numbers Assigned to Aircraft 1958 and Prior Prepared by: Procurement Division, Programmed Procurement Branch, Reports Section, MCPPSR, AF-WP-O-APR 61 250. Serials 44-84157 to 84389 were cancelled. 44-84390 is the start of Dallas P-51D-25, going to 44-84989 (600 aircraft)

Further, The Serial no. Blocks assigned to P-51H were 44-64169 through 44-64714.

Not quite correct, P-51H-1 44-64160/64179, H-5 44-64180/64459, H-10 44-64460/64714, note the first serial.

The USAAF view of what was going on, it published the monthly RC-301 report, in June 1945 it was 40 pages on what the USAAF thought its aircraft order status was. Wartime programs covered were the A program approved June 1940, B Approved September 1940, C (5th Supplemental) April 1941, D (12,000 modified) June 1941, E (1st Defence Aid) March 1941, F (2nd Defence Aid) October 1941, G (Follow on) January 1942, H (Acceleration) April 1942, I (Fiscal Year 1943) June 1942, J (Fiscal Year 1944) June 1943, K (Fiscal Year 1945) June 1944 and L (Fiscal year 1946) approved June 1945

Also included are the undetermined program, no approval date, covering aircraft like the P-400. Also the Army for Navy program, Experimental program, (XP-51 No cost AC-15471, XP-51F and G FP AC-37857, XP-51J FP AC-37857 Supp 4., XP-82 and XP-82A FP AC-2029), the Glider program, Target program and the Experimental Target and Glider programs. FP = fixed price

J program, status end June 1945 for incomplete P-51/F-6 contracts, plus the first P-82 as it has been mentioned.
P-82B, Inglewood, FP, AC-2384 20 a/c, expected completion January 1946
TP-51D, Dallas, FP, AC-2400, 2 a/c expected completion July 1945 (another 528 P-51D and 70 F-6D already accepted)
P-51D, Inglewood, FP, AC-3487, 4,000 a/c, expected completion July 1945
P-51H, Inglewood, FP, AC-1752, 1,000 a/c, expected completion October 1945

K program
P-51D, Dallas, FP, AC-2400 Supp 2,, 357 P-51D, expected completion August 1945
TP-51D, Dallas, FP, AC-2400 Supp 2, 8 a/c, expected completion July 1945
F-6D, Dallas, FP, AC-2400 Supp 2, 35 a/c, expected completion July 1945
P-51M, Dallas, FP, AC-8387, 629 a/c, expected completion June 1946 (Ordered in June 1945)
P-51H, Inglewood, FP, AC-1752 Supp 1, 1,400 a/c, expected completion February 1946
P-51H, Inglewood, FP, AC-8389, 2,400 a/c, expected completion September 1946
P-51M, Dallas, FP, AC-2400 Supp 2, 695 a/c, expected completion December 1945 (first acceptance in June 1945)
TP-51M, Dallas, FP, AC-2400 Supp 2, 75 a/c, expected completion October 1945
F-6M, Dallas, FP, AC-2400 Supp 2, 230 a/c, expected completion December 1945

Bringing total USAAF orders to, Inglewood
P-82B 20 ordered, none accepted, J program
P-51 148/148, E
P-51A 310/310, I
P-51B 1988/1988, H, I
P-51D 100/100, J (Contract AC-389, complete sets of airframes for Australia)
P-51D 6502/6301, H, J
P-51H 4900/128, J, K

Dallas
P-51C 1750/1750, H, I, J
P-51D 1454/1130, J, K
TP-51D 10/0, K
F-6D 136/101, J, K
P-51K 1337/1337, J
F-6K 163/163, J
P-51M 1324/1, K
TP-51M 75/0, K
F-6M 230/0, K

The figures do not include the various prototype P-51 and 620 Mustang mark I. Inglewood ceased P-51D production in July 1945, H in November. Dallas produced the TP-51D in July and August. The September 1945 RC-301 report has all P-51 contracts cancelled except for another 120 out of an order for 555 P-51H, while the XP-82A are listed as unscheduled.

What North American calls contract NA-124 the USAAF calls AC-2400 on 30 June 1944 for 600 aircraft from Dallas, Serial block 44-84390 to 84989 (528 P-51D-25, 70 F-6D-25, 2 TP-51D-25), and AC-2400 supplement 2 on 21 September 1944 for 1,400 aircraft, as listed above, of which 401 were accepted and the rest cancelled. Supplement 2 uses Serial block 45-11343 to 11743, comprising another 200 D-25, then 200 D-30 and 1 M-1, in serial number order. Serials 45-11744 to 12742, 999 aircraft, listed as cancelled.

P-51M-1 45-11743 is the last/highest serial number allocated to Dallas that was accepted, but the acceptance was in June 1945, as noted D production continued into August, 262 in June, 269 in July and 55 in August, total 586, versus 720 D-25 and 165 D-30, which means the M-1 was accepted before any D-30, and with somewhere between 159 and 421 D-25 to be accepted. F-6D acceptances were 37 in June, 33 in July and 2 in August 1945, of which 35 were D-30

From NAA , Airframe Contract Records, General Contract Administration "O" Reports dated 1-7-44, and per revision 8/45, the NA-124 contract was issued and completed as NAA Factory serial no's 124-4426 to 44845, Customer Serial No. 44-84246 to 849 and 45-11343 to 45-11743 at P-51D-30-NT.

The final 800 from Inglewood were D-30, which means they started appearing in May 1945, Inglewood P-51D production was 368 in May, 336 in June and 201 in July. If NA-124 was all D-30 that means the last 885 P-51D at Dallas, which says 4 in April then all D production from May to August, or D-30 started appearing at Dallas a couple of weeks before those from Inglewood.

Further, The XP-82 and P-51H replaced the NA-122 P-51D-30-NA as All SUBSEQUENT P-51D airframes were assigned to Dallas in mid 1945.

Except there is no shift of D production from Inglewood. Inglewood orders for 6,502 P-51D do not change in 1945. In January 1945 Dallas held orders for 4,600 P-51D, 200 accepted, and 1,500 P-51K, 1,127 accepted (Which is interesting as F-6K production started in November 1944 but no mention of them), end March 1945 the contracts stood at 4,501 P-51D, 99 F-6D, and the just completed 1,337 P-51K and 163 F-6K, April it was 2,501 P-51D and 99 F-6D after the cancellation of 2,000 P-51D on approved letter contracts (versus approved formal contracts), in May it was back up to 2,884 P-51D and 345 F-6D with the addition of 629 P-51D on approved letter contract and 146 P-51D changed to F-6D. And as noted before down to 1,454 P-51D, 10 TP-51D and 136 F-6D in June 1945, plus 1,629 M models of various types, again listed above. So in May there is a provisional order for another 629 aircraft, D models, but they are ordered as M. What does "assigned to Dallas in mid 1945." mean?

Clearly there are differences between what North American is reporting delivering and what the USAAF says it received. However given the response it is clear this forum is not the place to explore and resolve those differences. The P-51 is clearly a sacred object, with the law laid down by someone who knows all, do not contradict that.

 

[SaparotRob]

I thought the Messerschmidt BF-109 was the sacred object here.

 

[pbehn]

I thought the Messerschmidt BF-109 was the sacred object here.

With this talk of sacred objects and orthodoxy I think we are now in the realms of religious belief not aviation, Speer was a false god, whatever he said is proof that the opposite happened, I have been advised.

 

[SaparotRob]

HERETIC!!!!!

 

[special ed]

What difference does it make what NAA says it delivered versus what the USAAF says it got ..........unless, unless some P-51s are in railcars on a forgotten siding somewhere? Does it mean I MAY still have a chance at my P-51?

 

[pbehn]

What difference does it make what NAA says it delivered versus what the USAAF says it got ..........unless, unless some P-51s are in railcars on a forgotten siding somewhere? Does it mean I MAY still have a chance at my P-51?

All neatly stored in a tunnel under a mountain. Along with a hoard of gold and the Arc of the Covenant.

 

[MIflyer]

I read that postwarr, when they overhauled the airplanes and the engines they did not take pains to make sure that a -7 engine always got in a D or K model or -9 in an H model. So it would have been possible to have -9 engines in D's and K's and -7 engines in H's.

 

[drgondog]

Try the Index of AF Serial Numbers Assigned to Aircraft 1958 and Prior Prepared by: Procurement Division, Programmed Procurement Branch, Reports Section, MCPPSR, AF-WP-O-APR 61 250. Serials 44-84157 to 84389 were cancelled. 44-84390 is the start of Dallas P-51D-25, going to 44-84989 (600 aircraft)

The discussion was re: P-51M-NT, not P-51D-25. NAA Charge number NA-124 (AC-2400) resulted in 600 P-51D-25-NT (AC 44-84390 through 44-84989 plus 200 more P-51D-25-NT under NA-124 (AC-2400) (AC 45-11343 through 45-11542). Additionally, under NA-124 (AC-2400) 200 P-51D-30-NT (AC 45-11543 through 45-11742) PLUS one P-51M under NA-124 (AC-2400) serial 45-11743. The P-51M was to be #1 for a new block change for either -35-NT or P-51M with 1650-9A engine, but the rest of the contract extension for NA-124 was to be folded into another AC-2400 supplement - but cancelled and only the single M was completed in the Experimental Dept at Dallas.

Dallas plant was Never considered for future P-51H production, and the P-51M-NT was a P-51D-30 with the new 1650-NA engine. Period.

Also included are the undetermined program, no approval date, covering aircraft like the P-400. Also the Army for Navy program, Experimental program, (XP-51 No cost AC-15471, XP-51F and G FP AC-37857, XP-51J FP AC-37857 Supp 4., XP-82 and XP-82A FP AC-2029), the Glider program, Target program and the Experimental Target and Glider programs. FP = fixed price

Agreed.

J program, status end June 1945 for incomplete P-51/F-6 contracts, plus the first P-82 as it has been mentioned.
P-82B, Inglewood, FP, AC-2384 20 a/c, expected completion January 1946
TP-51D, Dallas, FP, AC-2400, 2 a/c expected completion July 1945 (another 528 P-51D and 70 F-6D already accepted)
P-51D, Inglewood, FP, AC-3487, 4,000 a/c, expected completion July 1945
P-51H, Inglewood, FP, AC-1752, 1,000 a/c, expected completion October 1945

K program
P-51D, Dallas, FP, AC-2400 Supp 2,, 357 P-51D, expected completion August 1945
TP-51D, Dallas, FP, AC-2400 Supp 2, 8 a/c, expected completion July 1945
F-6D, Dallas, FP, AC-2400 Supp 2, 35 a/c, expected completion July 1945
P-51M, Dallas, FP, AC-8387, 629 a/c, expected completion June 1946 (Ordered in June 1945)
P-51H, Inglewood, FP, AC-1752 Supp 1, 1,400 a/c, expected completion February 1946
P-51H, Inglewood, FP, AC-8389, 2,400 a/c, expected completion September 1946
P-51M, Dallas, FP, AC-2400 Supp 2, 695 a/c, expected completion December 1945 (first acceptance in June 1945)
TP-51M, Dallas, FP, AC-2400 Supp 2, 75 a/c, expected completion October 1945
F-6M, Dallas, FP, AC-2400 Supp 2, 230 a/c, expected completion December 1945

Bringing total USAAF orders to, Inglewood
P-82B 20 ordered, none accepted, J program
P-51 148/148, E

P-51-NA/Mustang IA, NA-91 DA-140, 150 delivered, 2 pulled for NA-101 XP-51B for AC-32073, 92 dellivered to RAF as Mustang IA, 56 to AAF as P-51-NA and multiples were converted to F-6.
No mention of A-36-1-NA, NA-97 AC 27396, 500 accepted by AAF, one sent to RAF.

P-51A 310/310, I
P-51B 1988/1988, H, I

The NA-102 AC-33823 was for 400 P-51B-1-NA. One was pulled to install Bubble canopy (Cockpit Enclosure, Sliding). Two spare NA-91 fuselages were sent to experimental hanger and also had the bubble canopy installed but also the six gun wing for the P-51D-NA and P-51D-1-NT - under NA 106 charge number and AC-30479 contract extension which began with P-51A. The NA-102 charge number delivered 400 P-51B-1

The NA-104 delivered 800 B-5-NA, 398 B-10-NA, 390 B-15-NA.
No mention of NA-106 (AC -30479) under which P-51D-NA and P-51D-1-NT serial number 42-106539/540 were built with first bubble canopy conversion, along with P-51B-1-NA 43-12102 - and flown in Q4 1943. No recitation of AC-30479 which was the contract vehicle for NA-99 P-51A-NA (-1, -5 -10), NA-104 for P-51B-5-NA, and -10-NA and -15-NA and P-51D-1-NA and P-51D-1-NT (but built in Inglewood with mixed Experimntal Department team as prototype for Dallas production)

P-51D 100/100, J (Contract AC-389, complete sets of airframes for Australia)

Plus One fully assembled P-51D-5-NA. Believe (have to check) that it was 44-13287 delivered to Australia intact in April 1945 - more than a year after it was actually delivered to AAF (first), then to RAAF by ship.

The figures do not include the various prototype P-51 and 620 Mustang mark I. Inglewood ceased P-51D production in July 1945, H in November. Dallas produced the TP-51D in July and August. The September 1945 RC-301 report has all P-51 contracts cancelled except for another 120 out of an order for 555 P-51H, while the XP-82A are listed as unscheduled.

What North American calls contract NA-124 the USAAF calls AC-2400 on 30 June 1944 for 600 aircraft from Dallas, Serial block 44-84390 to 84989 (528 P-51D-25, 70 F-6D-25, 2 TP-51D-25), and AC-2400 supplement 2 on 21 September 1944 for 1,400 aircraft, as listed above, of which 401 were accepted and the rest cancelled. Supplement 2 uses Serial block 45-11343 to 11743, comprising another 200 D-25, then 200 D-30 and 1 M-1, in serial number order. Serials 45-11744 to 12742, 999 aircraft, listed as cancelled.

As I noted - with more precision. Not to mention the fact that the figures apparently do not include various prototype 'P-51'. If not included, how can it be complete? I just cited two above that were pre-production but only prototype in context of first modification to P-51D configuration - but the Army paid for it and accepted them.

P-51M-1 45-11743 is the last/highest serial number allocated to Dallas that was accepted, but the acceptance was in June 1945, as noted D production continued into August, 262 in June, 269 in July and 55 in August, total 586, versus 720 D-25 and 165 D-30, which means the M-1 was accepted before any D-30, and with somewhere between 159 and 421 D-25 to be accepted. F-6D acceptances were 37 in June, 33 in July and 2 in August 1945, of which 35 were D-30

The final 800 from Inglewood were D-30, which means they started appearing in May 1945, Inglewood P-51D production was 368 in May, 336 in June and 201 in July. If NA-124 was all D-30 that means the last 885 P-51D at Dallas, which says 4 in April then all D production from May to August, or D-30 started appearing at Dallas a couple of weeks before those from Inglewood.

Except there is no shift of D production from Inglewood. Inglewood orders for 6,502 P-51D do not change in 1945. In January 1945 Dallas held orders for 4,600 P-51D, 200 accepted, and 1,500 P-51K, 1,127 accepted (Which is interesting as F-6K production started in November 1944 but no mention of them), end March 1945 the contracts stood at 4,501 P-51D, 99 F-6D, and the just completed 1,337 P-51K and 163 F-6K, April it was 2,501 P-51D and 99 F-6D after the cancellation of 2,000 P-51D on approved letter contracts (versus approved formal contracts), in May it was back up to 2,884 P-51D and 345 F-6D with the addition of 629 P-51D on approved letter contract and 146 P-51D changed to F-6D. And as noted before down to 1,454 P-51D, 10 TP-51D and 136 F-6D in June 1945, plus 1,629 M models of various types, again listed above. So in May there is a provisional order for another 629 aircraft, D models, but they are ordered as M. What does "assigned to Dallas in mid 1945." mean?

You use P-51D indiscriminantly. There is a protocol for Dallas -NT and for Inglewood -NA. It confuses your message. P-51D-30-NA and P-51D-30-NT can coexist as "-30", but built as NT or NA. Until you learn this you will forever confuse what you are reading.

The M was an extension of the P-51D-30-NT, which was 100% produced in DALLAS. I don't understand your confusion regarding "Assigned to Dallas in mid 1945". If the "P-51M" had been assigned to Inglewood, probably as an extension of NA-122 (AC-2378), it would have succeeded P-51D-30-NA last delivered as 44-75026. I doubt that 44-75027 and Subsequent were available, but it would not have been a problem for M (45-11743 and Subsequent for 629 ships) to have both the NA Factory Serial No to change site of production if planned early enough to re-route material.

An example of sequential serial number block switching from one plant to another is that the AC Serial No block following the the last P-51D-20-NT (44-13252 (NA-111 AC-40063) delivered in March 1945, was NA-109 (AC 40064) P-51D-5-NA 44-13253 delivered in February 1944.

Clearly there are differences between what North American is reporting delivering and what the USAAF says it received. However given the response it is clear this forum is not the place to explore and resolve those differences. The P-51 is clearly a sacred object, with the law laid down by someone who knows all, do not contradict that.

No, sir. There are differences between what You report via Army reports and what NAA production and NAA Financial/Contracts report seem to be somewhat out of snch but both of the latter agree with the Individual Aircraft Records for each aircraft delivered to and accepted by the Army (USAAF) contract officer residing at Inglewood and Dallas (for P-51 examples).

You clearly are experiencing some distress regarding 'sacred objects and laid down law'. How can I help?

 

[drgondog]

Try the Index of AF Serial Numbers Assigned to Aircraft 1958 and Prior Prepared by: Procurement Division, Programmed Procurement Branch, Reports Section, MCPPSR, AF-WP-O-APR 61 250. Serials 44-84157 to 84389 were cancelled. 44-84390 is the start of Dallas P-51D-25, going to 44-84989 (600 aircraft)

Cursory examination of your presented data from '1958' displays many errors - the most agregious related to P-51H-NA and XP/P/F-82 production and acceptance delivery numbers.
Totally absent are the NA-106 P-51D-NA and P-51D-1-NT, 42-106539/540 as #1 and #2 of original P-51D contract which was stopped at #2. All funding for NA-106 was folded into NA-109 beginning with P-51D-5-NA #1 44-13253 delivered in Feb 1944.

Note for your consideration - There were quite a few All Weather Interceptor F-82 flying, which according to you, 'not accepted' category but somehow made into USAAF/USAF inventory (272 incl 2 XP-82 and 18 P-82B w/Packard 1650 engines).

No discussion of the various supplements to AC-30479, or AC-33923 (P-51B-1) or AC-33940 (P-51C-NT) or AC-40063 (combined P-51C-10 third block and P51D-5-NT) which then was supplemented for all extensions of P-51D-NT and P-51K-NT blocks.

K program
P-51D, Dallas, FP, AC-2400 Supp 2,, 357 P-51D, expected completion August 1945
TP-51D, Dallas, FP, AC-2400 Supp 2, 8 a/c, expected completion July 1945
F-6D, Dallas, FP, AC-2400 Supp 2, 35 a/c, expected completion July 1945
P-51M, Dallas, FP, AC-8387, 629 a/c, expected completion June 1946 (Ordered in June 1945)
P-51H, Inglewood, FP, AC-1752 Supp 1, 1,400 a/c, expected completion February 1946
P-51H, Inglewood, FP, AC-8389, 2,400 a/c, expected completion September 1946
P-51M, Dallas, FP, AC-2400 Supp 2, 695 a/c, expected completion December 1945 (first acceptance in June 1945)
TP-51M, Dallas, FP, AC-2400 Supp 2, 75 a/c, expected completion October 1945
F-6M, Dallas, FP, AC-2400 Supp 2, 230 a/c, expected completion December 1945

Bringing total USAAF orders to, Inglewood
P-82B 20 ordered, none accepted, J program

20 produced, 20 accepted, 2 converted to P-82C and D respectively according to NAA and IARCs

P-51 148/148, E

150 produced, 150 accepted, 56 retained for AAF Training and Tactical purposes as P-51-NA and F6, 2 retained as airframe to be modified later as XP-51B, 92 shipped to RAF as Mustang IA via Lend Lease.

P-51A 310/310, I
P-51B 1988/1988, H, I
P-51D 100/100, J (Contract AC-389, complete sets of airframes for Australia)
P-51D 6502/6301, H, J

6500 P-51D-NA from -5 through -30 unders AC-40064 NA-109 and NA-122. Two converted pre-production P-51D-1-NA and D-1NT converted from P-51B-1-NA Spare fuselage/new P-51D canopy. 6502 delivered. From those delivered and accepted, 282 went to RAF under Lend Lease and 163 went to RAAF post war

P-51H 4900/128, J, K

2500 P-51H first ordered under AC-1752 NA-117 but converted to NA-126 and reuced to 555 ordered and delivered. P-51H-10 44-64714 was #555 produced and accepted November 1945 according to the IARC.

Dallas
P-51C 1750/1750, H, I, J

Correct, under two seprate contracts and NA Charge numbers.

P-51D 1454/1130, J, K

2100 P-51D-NT (incl D-5, D-20, D-25, K-1, -5, -10, -15) under NA-111 AC-40063. so, 600 D-NT and 1500 K-NT in your format ordered and delivered.
1001 P-51D-NT (including D-20, -25, and M) produced after orders reduced to 1001 under NA-122 AC 2400
SO 1601 P-51D-NT ordered and delivered and 1500 P-51K-NT ordered and delivered.
All verified by both NAA Contractor Report (s) through 1957. Verified by IARCs of AAF acceptance by serial number and dates.

TP-51D 10/0, K

These are NOT new a/c ordered but as modifications of 10 already delivered airframes at NAA Dallas (P-51D-25-NT). 15 more converted in 1951 at Temco, Greenville TX

F-6D 136/101, J, K

136, 136

P-51K 1337/1337, J

P-51K 1500/1500 as noted above.

F-6K 163/163, J
P-51M 1324/1, K
TP-51M 75/0, K
F-6M 230/0, K

The figures do not include the various prototype P-51 and 620 Mustang mark I. Inglewood ceased P-51D production in July 1945, H in November. Dallas produced the TP-51D in July and August. The September 1945 RC-301 report has all P-51 contracts cancelled except for another 120 out of an order for 555 P-51H, while the XP-82A are listed as unscheduled.

Clearly there are differences between what North American is reporting delivering and what the USAAF says it received. However given the response it is clear this forum is not the place to explore and resolve those differences. The P-51 is clearly a sacred object, with the law laid down by someone who knows all, do not contradict that.

You are quoting USAF records which seem to be a compilation from AAC/AAF records from Materiel Command at Wright Field and HQ-AAF both during and post VJ Day. True/Not True? Dated reports enclosed would support source docs, otherwise - copy and paste with what QA process to check for errors.

After all this, do you see any possibility that your sources are seriously flawed re:NAA production and delivery numbers? Did you even make a cursory check with Bob Gruenhagen and Ray Wagner publications? Do you have access to the source documents (NAA/IARC) for 2nd check?

 

[Geoffrey Sinclair]

The discussion was re: P-51M-NT, not P-51D-25. NAA Charge number NA-124 (AC-2400) resulted in 600 P-51D-25-NT (AC 44-84390 through 44-84989 plus 200 more P-51D-25-NT under NA-124 (AC-2400) (AC 45-11343 through 45-11542).

Actually the discussion was expanded to the final order(s) from Dallas, the NA-124 contract, which had the claim "Customer Serial No. 44-84246 to 849 and 45-11343 to 45-11743 at P-51D-30-NT", which contradicts the USAAF reports showing plenty of D-25, furthermore North American keep saying all P-51 while the USAAF says P-51, TP-51 and F-6. I do note the new starting serial number. And how the P-51M rule is relaxed when adding details to earlier orders.

Dallas plant was Never considered for future P-51H production, and the P-51M-NT was a P-51D-30 with the new 1650-NA engine. Period.

So even though it was accepted before D-30 production began at Dallas, it was made up to D-30 standard, then fitted with a different engine is what North American report.

Next we have additional detail added to the list of orders, you know for P-51B etc. "The discussion was re: P-51M-NT" I did not put the boring detail in for earlier orders, so time for experts to add the never boring pertinent details.

Plus One fully assembled P-51D-5-NA. Believe (have to check) that it was 44-13287 delivered to Australia intact in April 1945 - more than a year after it was actually delivered to AAF (first), then to RAAF by ship.

It was 44-13293 which became A68-1001, first flight in Australia 23 April 1945, the RAAF received its first lend Lease P-51 on 16 April.

As I noted - with more precision. Not to mention the fact that the figures apparently do not include various prototype 'P-51'. If not included, how can it be complete? I just cited two above that were pre-production but only prototype in context of first modification to P-51D configuration - but the Army paid for it and accepted them.

Try less precision and with errors. Yet another invent something, assign it to the other person, and add dazzling expertise. Where is the claim the list is complete, more so as I explicitly state the prototypes are excluded?

The M was an extension of the P-51D-30-NT, which was 100% produced in DALLAS. I don't understand your confusion regarding "Assigned to Dallas in mid 1945". If the "P-51M" had been assigned to Inglewood, probably as an extension of NA-122 (AC-2378), it would have succeeded P-51D-30-NA last delivered as 44-75026. I doubt that 44-75027 and Subsequent were available, but it would not have been a problem for M (45-11743 and Subsequent for 629 ships) to have both the NA Factory Serial No to change site of production if planned early enough to re-route material.

Maybe it is because the assigned claim was for P-51D? Which is not reflected in the USAAF reports given Inglewood D orders did not change? While Dallas
started 1945 producing K, with the fulfilled intention to switch back to D but the D numbers being revised at times before being finalised and the switch to M planned. The single M had the highest serial issued, but it was far from the last P-51 accepted from Dallas. What "All SUBSEQUENT P-51D airframes were assigned to Dallas in mid 1945" actually means given the USAAF documents, which show if anything D airframes on order from Dallas in early 1945 were cancelled/replaced with M airframes. Not some switched from Inglewood.

You use P-51D indiscriminantly. There is a protocol for Dallas -NT and for Inglewood -NA. It confuses your message. P-51D-30-NA and P-51D-30-NT can coexist as "-30", but built as NT or NA. Until you learn this you will forever confuse what you are reading.

Actually I have been quite clear with allocations by factory, but since I did not bore people with the designation time to tell that experts use it.

No, sir. There are differences between what You report via Army reports and what NAA production and NAA Financial/Contracts report seem to be somewhat out of snch but both of the latter agree with the Individual Aircraft Records for each aircraft delivered to and accepted by the Army (USAAF) contract officer residing at Inglewood and Dallas (for P-51 examples).

Go reread your message " NAA Factory serial no's 124-4426 to 44845, Customer Serial No. 44-84246 to 849 and 45-11343 to 45-11743 at P-51D-30-NT. " which is not what the USAAF reports, both serials and versions and even your later corrections.

Cursory examination of your presented data from '1958' displays many errors - the most agregious related to P-51H-NA and XP/P/F-82 production and acceptance delivery numbers. Totally absent are the NA-106 P-51D-NA and P-51D-1-NT, 42-106539/540 as #1 and #2 of original P-51D contract which was stopped at #2. All funding for NA-106 was folded into NA-109 beginning with P-51D-5-NA #1 44-13253 delivered in Feb 1944.

Note for your consideration - There were quite a few All Weather Interceptor F-82 flying, which according to you, 'not accepted' category but somehow made into USAAF/USAF inventory (272 incl 2 XP-82 and 18 P-82B w/Packard 1650 engines).

Now onto the second message. Of course if my message had been read correctly it would be noted the production numbers were as of end June 1945, not all time. The 1958 document is a list of serial numbers by type/order, the RC-301 reports have the production numbers.

Of course if my message had been read correctly it would be noted contract details only covered orders still outstanding as of end June 1945, however since the earlier ones were not put in they are added, if I put them in it would be boring, or dismissed under "The discussion was re: P-51M-NT"

The main contents of message 17 are based in a total misread of the June 1945 figures with bonus errors. Note the expected completion date of the P-82 order for example in my message.

150 produced, 150 accepted, 56 retained for AAF Training and Tactical purposes as P-51-NA and F6, 2 retained as airframe to be modified later as XP-51B, 92 shipped to RAF as Mustang IA via Lend Lease.

Talking about P-51, 150 ordered, 2 accepted as XP-51B in August 1942, 148 accepted as P-51.

6500 P-51D-NA from -5 through -30 unders AC-40064 NA-109 and NA-122. Two converted pre-production P-51D-1-NA and D-1NT converted from P-51B-1-NA Spare fuselage/new P-51D canopy. 6502 delivered. From those delivered and accepted, 282 went to RAF under Lend Lease and 163 went to RAAF post war

Australia imported 262 P-51 16 April to 12 August 1945, that is wartime, for the RAAF, the original order of 285 was reduced to 284 when 1 was lost in a transit
flight from the factory, then increased to 499 of which ultimately 298 were delivered, as the 36 on the way when Japan surrendered were not turned around, all were in the country by the end of the second week of September 1945. 84 K models, 214 D models, total 298, plus A68-1001 the pattern, total 299.

By the way the ADF serials website Mustang page says all the D models received except A68-1001 were NT. I have not checked the RAF totals.

20 produced, 20 accepted, 2 converted to P-82C and D respectively according to NAA and IARCs

The RC-301 reports note 18 P-82B, 1 C and 1 D accepted.

These are NOT new a/c ordered but as modifications of 10 already delivered airframes at NAA Dallas (P-51D-25-NT). 15 more converted in 1951 at Temco, Greenville TX

The US recorded aircraft production at acceptance, after which the aircraft were delivered. USAAF reports it accepted 10 TP-51D, 6 in July and 4 in August 1945, not had 10 P-51D delivered and then converted.

P-51K 1500/1500 as noted above.

So where did the F-6K come from?

You are quoting USAF records which seem to be a compilation from AAC/AAF records from Materiel Command at Wright Field and HQ-AAF both during and post VJ Day. True/Not True?

As already noted the monthly USAAF RC-301, being a monthly it was published in the days after the month in question. The full title for the September 1945 report is
RC-301 A.A.F. Aircraft Procurement Programs Fiscal Year Funds 1941-1946.
Number of Aircraft - On Program - On approved formal contract - on A.F.P. or unapproved letter contract - on C.T.I releases, no procurement action.
And number accepted to date.
Prepared by Air Technical Service Command, TSBPA2C, WF-4-10-45-143.
There follows a half page introduction and general definitions section.

Dated reports enclosed would support source docs, otherwise - copy and paste with what QA process to check for errors.

You mean like someone looking at the total acceptances to end June 1945 then saying they are all wrong, and putting in the total all time acceptances instead?

After all this, do you see any possibility that your sources are seriously flawed re:NAA production and delivery numbers?

Go back and read the text, the list of acceptances is as of end June 1945, not all time. As a marker note how the mentioned XP-82A were not built. Or perhaps all those "expected completion" dates. Once again when stuck invent a claim and hand it to another person then show dazzling expertise by refuting the claim.

Did you even make a cursory check with Bob Gruenhagen and Ray Wagner publications? Do you have access to the source documents (NAA/IARC) for 2nd check?

Beyond checking the figures against the USAAF Statistical Digest, War Production Board, CAA production reports, some US Archives files plus in other archives as the allies were sharing the information. (Some good Canadian figures are on the Australian Archives web site, no need to visit, but note the USAAF, USN and CAA and I believe the WPB co-ordinated to come up with one set of official figures)

One of the reasons for putting the figures onto the forum was a quality check, but as noted at the end of the message "given the response it is clear this forum is not the place to explore and resolve those differences".

Perhaps take a step back and note my comments on the M total here is what the USAAF says it was, this is when it was accepted and despite being the last serial number it was accepted a couple of months before end of production.

The documents needed are the USAAF ones giving the specification of the P-51M and the trail to explain as of June 1946, a year after the P-51M was accepted, why the USAAF says the M used the H fuselage.

Then, if the major production of the M was going to be the D with a new engine, comes understanding what was the advantage of complicating supply by having 2 different P-51 airframes in service, why the advantages of the H airframe were not considered worth it, why a more powerful engine, therefore more heat, could still use the existing radiator, why a more powerful engine, therefore more torque, could still use the existing tail.

You clearly are experiencing some distress regarding 'sacred objects and laid down law'. How can I help?

Notes about sacred, 2 replies to the first message about 30 minutes apart then 2 replies to the second one, 18 hours apart. I had no distress, noting the level of the reaction. After all I made a 5 line post, quoting the reference, and instead of a reply along the lines of the North American documentation disagrees, it was one of for your edification with the jarring sideline the serial number blocks were wrong, plus the implication the entire order was P-51D-30, that was real good edification, hence the laying down of the law comment. Plus a follow up, with NAA Contractor reports mentioned but of course no information on how to access them. Since the serials were wrong and they were not all D-30 I spent a few minutes and pulled the data on the relevant contracts and that produced another pair of replies, filling in any detail I chose to omit while proclaiming how it was all about the M and misreading what I had wrote.

You are aware the way you project ideas onto other people and how the above reactions indicate a significant amount of ego and/or emotional investment in the topic? Whether that is distress or not is another matter.

There is little you could help since given the attitude displayed, all claimed help would need to be double checked, so doing it unaided will be about the same effort, help could be provided to the general readership by the admission of the original errors in serials and order composition, followed by the misreading of the to end June 1945 acceptance figures to become all time acceptances clarified. After all you have set people up to be recorded endorsing an error riddled message based on a failure to accurately read the supplied data.

Otherwise how about settling for becoming a better human being, on this topic anyway?

Three of the main voices in this corner of the internet are comfortable making even self contradicting claims while ignoring any problems and most errors, making it a sort of intellectual retirement playpen area where as so many mothers have said to daughters, remember dear, men will be boys.

 

[drgondog]

Hi all,
Lately this question has been confusing the heck out of me. The Production section of the main Mustang page on Wikipedia says the P-51M is a variant of the D:

On the North American P-51 Mustang variants page on Wiki this appears in the P-51H section (my italics):

Yet, in the Summary of P-51 variants, we're back to the idea M = D variant:

On the Secret Projects forum writer Steve Pace posted a photo of a Mustang serialled 45-11742 and said it was an M. He later contacted Boeing for info and got this reply:

Steve ended up with more research that suggests the P-51M was indeed a re-engined D and not a variant of the H.

So which is right? Can the M = H concept be put out to pasture?

M= P-51D-30-NT #1001, modified with V-1650-9A. Similar to P-51D-30-NT save the engine. It had Zero common parts with P-51H except for gunsight and a couple of phenolic parts (ejection chutes) plus a couple others which I can't remember offhand. The H and P-82 had significant commonality.

Steve was wrong initially, and had posed the question on p51sig.com - was steered correctly, but it failed to make it into print. Ditto his discussions of geneology of the P-51D

The easiest way to keep this straight is that P-51H-NA tooling, parts and factory set up were all in Inglewood and nothing related to P-51H was ever dulicated at Dallas.

Much of 'internet lore' is cut and paste from prior authors instead of sourcing original docs.

 

[drgondog]

Actually the discussion was expanded to the final order(s) from Dallas, the NA-124 contract, which had the claim "Customer Serial No. 44-84246 to 849 and 45-11343 to 45-11743 at P-51D-30-NT", which contradicts the USAAF reports showing plenty of D-25, furthermore North American keep saying all P-51 while the USAAF says P-51, TP-51 and F-6. I do note the new starting serial number. And how the P-51M rule is relaxed when adding details to earlier orders.

So even though it was accepted before D-30 production began at Dallas, it was made up to D-30 standard, then fitted with a different engine is what North American report.

Are you are laboring under an impression (or even the Air Force preparers of documents understood) that the actual shipset order of production line is 100% consistent with serial number order on the production line? Please don't. Many contrary examples.

Specials were fabricated or modified from a ship in the line (or after acceptance, per a new MCR) and moved to another location for the work (like Exp.Dept./Adv.Prod) where all the drawings and Engineering orders, special GFE like Packard 1650 for XP-51B) were sent to the fabrication team.

In the case of the P-51M-NT #1, it could have been the first P-51D-30-NA (blank), moved to experimental shop before the D-30 line proceeded. Additionally, P-51M could have been built from -25 Spares prior to end of P-51D-25-NT line. Without seeing the actual project notes and ECO's associated with P-51M, I would speculate that it immediately followed last -25-NT and before D-30-NT #1, with forecast serial number for #1001 reserved for P-51M #1.

As an illustration, the P-51D-NA was modified in the Experimental Production Department and began life as NA-102 fuselage spare in July 1943, was modified in accordance with MCR-258 and NA-106 design and Specifications, accepted the first six gun NA-106 wing and second NA-106 Cockpit Enclosure - Sliding. The original NA-106 contract had the production insert point for All future P-51Ds at the end of projected P-51B-10 line at 42-106538. Follow closely here - P-51D-NA #1 was completed two months before the first P-51B-10-NA was completed, and was assigned 42-106539 in November 1943. NA-106 production plans were scrapped (for P-51D-NA 42-106541 & Subsequent)when only 55gal fuselage tank could be installed in P-51D-1-NT (#2) 42-106540 and all useful parts storage was released to NA-104 for future P-51B-10-NA production.

For your benefit, the NAA production docs and AAF IARC show that mid block P-51B-10 42-106538 was accepted 2-7-44 (15 weeks after P-51D-NA). The first of 200 P-51B-10-NA 43-7113 on 12-6-43. The first P-51D-NA was accepted 10-25-1943.

The lesson is that at NAA ships were not all assigned their final actual delivery serial number for data block and tail number, and internal data plate until just before moving to paint shop.

Next we have additional detail added to the list of orders, you know for P-51B etc. "The discussion was re: P-51M-NT" I did not put the boring detail in for earlier orders, so time for experts to add the never boring pertinent details.

It was 44-13293 which became A68-1001, first flight in Australia 23 April 1945, the RAAF received its first lend Lease P-51 on 16 April.

Correct, I stated that I would check the IARC. It was accepted by AAF on 4-20-1944 as #41 P-51D-5-NA. Transport by sea April 1945, accepted by RAAF on dates you noted and assigned A68-1001. The original Australian contract with NAA pointed to NA-107 projected for P-51D-1-NT production, but changed to specify NA-109 with 6x50 cal guns. That parallel discussion points to Dallas for supply of 100 Parts Kits.

Maybe it is because the assigned claim was for P-51D? Which is not reflected in the USAAF reports given Inglewood D orders did not change? While Dallas
started 1945 producing K, with the fulfilled intention to switch back to D but the D numbers being revised at times before being finalised and the switch to M planned.

You are flailing. The 'K' was uninterrupted P-51D-5-NT line save replacement of prop/spinner for AeroProducts propeller. If you look at NAA records you will see P-51K-1-NT #1 begins immediately following D-5-NT #200, for K #1 in serial number sequence' and continues in sequence through K-15-NT #1600 44-12852, where Hamilton Standard propellers were once again installed in the P-51D-NT line beginning with P-51D-20-NT 44-12853. The P-51K line began in September 1944 and completed as F6K 44-12852 and accepted by AAF on 3-14-1945.

Talking about P-51, 150 ordered, 2 accepted as XP-51B in August 1942, 148 accepted as P-51.

P-51-NA, 150 ordered, 150 accepted, XP-51B contract called for set aside of two P-51-NA completed airframes from AAF inventory to be retained for the Packard modification (#33 and #99) under different contract AC-32073 and charge number NA-101. I'll have to check IARC, but first flight of XP-51B 41-37352 was not until November 30, 1942 - doubt that AAF accepted the Modified Airframe per the implied NA-101 MCR until Spring 1943.

Australia imported 262 P-51 16 April to 12 August 1945, that is wartime, for the RAAF, the original order of 285 was reduced to 284 when 1 was lost in a transit
flight from the factory, then increased to 499 of which ultimately 298 were delivered, as the 36 on the way when Japan surrendered were not turned around, all were in the country by the end of the second week of September 1945. 84 K models, 214 D models, total 298, plus A68-1001 the pattern, total 299.

By the way the ADF serials website Mustang page says all the D models received except A68-1001 were NT. I have not checked the RAF totals.

The 100 kits were K, hence NT but unknown whether the order (at NAA) to prepare kits were drawn from a special Spares run or from staging bins for which an extra run were subcontracted, but Dallas was the source. P-51D-5-NA 44-13293 was a completed (obviously) NA-109 'standard' which RAAF specified with mod to accept the AeroProduct K version.

The RC-301 reports note 18 P-82B, 1 C and 1 D accepted.

The US recorded aircraft production at acceptance, after which the aircraft were delivered. USAAF reports it accepted 10 TP-51D, 6 in July and 4 in August 1945, not had 10 P-51D delivered and then converted.

Well, there ya go. There was no special and unique NAA charge number for 'TF-51D'. Very similar to addition of 85 gallon fuel tank, modification for bubble canopy, installation of cameras - in which a Material Change Request for 2 seat/control mod, was made by NAA to AAF spec, funded, added to the Model Specifiction (in this case original P-51D-5-NT Specification) as MCR-xxx, engineering and production work performed under AC-2400 contract. NAA Charge number NA-124. It was modified from a basic P-51D-25-NT airframe. I would have to look at the IARC for date and travel records to see if it was a.) accepted but delivered with gap of dates for delivery, or b.) accepted and delivered within a day or two. Payment for a complete ship, pre agreed modification/pre acceptance would have been a point of negotiation. If the latter, then they were delivered per the MCR and then accepted based on meeting the MCR spec..

The IARC will control the facts.

Introduce yourself to a brave new world and Look them up?

To the point of USAAF definition of accepted vs delivered then accepted, vs accepted but retained at NAA I can point to several examples in which the Mod was performed after delivery, after acceptance. Do you suppose AAF Materiel Command cared for the finer distinctions?

,
So where did the F-6K come from?

F6K were modified at Dallas in Advanced Production and part of the P-51K-NT run. Prior F-6, F-6A, B/C/D were largely Depot mods post acceptance by AAF

Go back and read the text, the list of acceptances is as of end June 1945, not all time. As a marker note how the mentioned XP-82A were not built. Or perhaps all those "expected completion" dates. Once again when stuck invent a claim and hand it to another person then show dazzling expertise by refuting the claim.

The original contract AC-2029 NA-120 for XP-82 called for four, Reduced to two. Two delivered. There is no 'XP-82A" or XP-82B in NAA Charge Number, nor is the use of A or B for a prototype a NAA practice for a wholly new Type. Whether typo or simply brain freeze, there was no XP-82A.

Recall that the two pulled P-51-NA forPackard installation were originally XP-78, and changed to XP-51B - after P-51A was in production. The NA-102 P-51B-1-NA contract was executed before the P-51A contract was converted to P-51B-5-NA production under NA-104. While there was a P-51D and P-51E,there was never an XP-51D.

Beyond checking the figures against the USAAF Statistical Digest, War Production Board, CAA production reports, some US Archives files plus in other archives as the allies were sharing the information. (Some good Canadian figures are on the Australian Archives web site, no need to visit, but note the USAAF, USN and CAA and I believe the WPB co-ordinated to come up with one set of official figures)

Did you research the AAF IARC's ? Kinda fundamental as they refected day by day aircraft deliveries by date, mfr, contract, serial number, type and model - as well as the movements of each aircraft through loss or salvage? Did you research the NAA Contractor and O Reports, listing every aircraft built by NAA, every Customer/contract, NAA Charge number, NA production number, AAC/AAF serial number, important descriptions?

But you merrily baffle the rapt readers with a blizzard of bullshit, hoping that volume=quality in everyone's mind. I can 'baffle' with most, but for sheer blind acceptance of other person's/agencies top level reporting as indisputable fact - you are Da King.

I draw your attention (as you have) to the basic debate; P-51M 'equal P-51H-NA w/different engine' or 'equal P-51D-30-NT w/different engine'.

Your conclusion Da King?