Effects of converting of all surviving Mustang Is into LR Mustang X?

[tomo pauk]

People are probably aware that British up-engining of the handful of Mustang Is 'produced' high-performance fighters, that were generally named the Mustang X. So let's have British convert all of the surviving Mustang Is and IAs (4-cannon version, very similar to the P-51) into a Mustang X configuration, featuring also the drop-tank installation under the wings (something not being done on the Mk.X historically) for the good measure. Squadron service by April 1943, with 200+- fighters in service by July 1943.

How this changes the WAllied air war and their aircraft of 1943? In 1st half of 1944?
German response?

 

[Peter Gunn]

People are probably aware that British up-engining of the handful of Mustang Is 'produced' high-performance fighters, that were generally named the Mustang X. So let's have British convert all of the surviving Mustang Is and IAs (4-cannon version, very similar to the P-51) into a Mustang X configuration, featuring also the drop-tank installation under the wings (something not being done on the Mk.X historically) for the good measure. Squadron service by April 1943, with 200+- fighters in service by July 1943.

How this changes the WAllied air war and their aircraft of 1943? In 1st half of 1944?
German response?

 

[EwenS]

It is impossible in your timescale.

Idea floated 30 April 1942. Authorised 12 August. Prototypes first flew Oct-Dec 1942. Then it would have needed productionised (there were variations between the various conversions), facilities and resources found to do the conversions etc etc in wartime Britain workingbto the max. It would be lucky if it could even have been started production by mid 1943 when you want 200+ in service. And you have a non standard aircraft type with a mix of US and British parts.

Meanwhile US attache in London advised of possibility in May. 25 July conversion of 2 aircraft by North American authorised by USAAF. Order for 400 placed August based on performance estimates. Prototype P-51B flies 30 Nov. Production starts May 1943 and say usual 4-5 months from factory door to front line. RAF equips its first squadron in Dec 1943 the month after the first US P-51B unit arrives in Britain.

I really don't see it as being worth the effort when the aircwar in the early part of 1944 is over northern France. By late 1944 when Bomber Command begins daylight raids there are enough P-51B/C/D/K available to allow conversion of many RAF squadrons.

Edit N.A. production is on a line that was already up and running and as a follow on to the A-36.

 

[tomo pauk]

It is impossible in your timescale.

Idea floated 30 April 1942. Authorised 12 August. Prototypes first flew Oct-Dec 1942. Then it would have needed productionised (there were variations between the various conversions), facilities and resources found to do the conversions etc etc in wartime Britain workingbto the max. It would be lucky if it could even have been started production by mid 1943 when you want 200+ in service. And you have a non standard aircraft type with a mix of US and British parts.

I haven't suggested production, but conversion. 2-stage Merlins are very standard, so is the Mustang I airframe.

But again, it is probably much better that, for example, Hawker continues making Hurricanes in 1943.

 

[EwenS]

I haven't suggested production, but conversion. 2-stage Merlins are very standard, so is the Mustang I airframe.

But again, it is probably much better that, for example, Hawker continues making Hurricanes in 1943.

I realised you were not talking about production from scratch. For the numbers you envisage in the timescale you proposed some kind of production line needs set up to carry out the conversions. It would be the only efficient way of doing it.

But a productionised and standardised version still needs designed and agreed on, not some hand built prototypes. There is a clue to the effort involved in the 100 early Spitfire IX conversions from Spitfire V. That resulted in variations between those converted by Supermarine and Rolls Royce. Incidentally that exercise involved 168 modifications. And it took 3 months. You are planning a far bigger programme for the Mustang and have the headache of marrying US and British parts.

If you plan on using an existing manufacturer you then have a hiatus while the changeover occurs. Production of some other type is then lost. Or are you planning to do it at an MU somewhere? But these units are not idle.

OK the Hawker Hurricane was out of date by 1943, but it was still fulfilling a useful fighter bomber role in the Far East until the end of the war, and with a couple of squadrons in the Med. What are you proposing to plug those gaps? And what are you going to replace those Tac/R Mustang I/IA in Britain with in 1943/44?

That is the problem with what ifs. No one wants to think of the butterfly effect.

Edit - and one other thing. Do you have the 200+ Merlin 60 series engines available or will you have to sacrifice 200+ Spitfire VIII/IX to get your Mustang X?

 

[tomo pauk]

But a productionised and standardised version still needs designed and agreed on, not some hand built prototypes. There is a clue to the effort involved in the 100 early Spitfire IX conversions from Spitfire V. That resulted in variations between those converted by Supermarine and Rolls Royce. Incidentally that exercise involved 168 modifications. And it took 3 months. You are planning a far bigger programme for the Mustang and have the headache of marrying US and British parts.

If you plan on using an existing manufacturer you then have a hiatus while the changeover occurs. Production of some other type is then lost. Or are you planning to do it at an MU somewhere? But these units are not idle.

OK the Hawker Hurricane was out of date by 1943, but it was still fulfilling a useful fighter bomber role in the Far East until the end of the war, and with a couple of squadrons in the Med. What are you proposing to plug those gaps? And what are you going to replace those Tac/R Mustang I/IA in Britain with in 1943/44?

Winning the ww2 is about beating Germany. No offense to the servicement fighting and dying on other ww2 theaters. Allies in Burma/India will had to make do with Spitfires, P-40s, P-47s, P-51A and later P-51C.
Tac/R in 1943 based in UK has no Army in fight to support. In 1944, there is a much more of Merlin Mustangs to have. And/or use the P-47s, Typhoons or P-47s.

That is the problem with what ifs. No one wants to think of the butterfly effect.

I want. Together with talk about priorities.

Edit - and one other thing. Do you have the 200+ Merlin 60 series engines available or will you have to sacrifice 200+ Spitfire VIII/IX to get your Mustang X?

Sacrifice them.

 

[tomo pauk]

Possible effects to the Allied 'hardware' in 1943 (both in-service and to what is in pipeline), after the 1st combat reports are received:
- a more focused effort to outfit the P-47s with drop tanks
- earlier 'drive' to have Spitfires outfitted with more internal fuel, mostly the Mk. VII, VIII, IX and later the XIV
- Tempest with 180-190 gal of internal fuel from the get-go - no waiting until second half of 1944

Possible Luftwaffe response:
- Jumo 213A and/or DB 603 installed on the Fw 190 by winter of 1943/45 instead of late 1944 (Me 410 meets a quick end, Ju 188 is BMW-only)
- going all-in with jet-powered fighters; granted, this is limited by availability, reliability and fuel consumption of the jet engines
- jet engine in the nose of Bf 109 or Fw 190, a-la Yak-15 (good for performance, bad for fuel consumption)
- greater application of GM-1 if possible
- BMW 801J installed on the Fw-190 instad on the Ju 388

Luftwaffe still fights badly out-numbered.

 

[wuzak]

Maybe make more Spitfire XIIs in place of IXs?

Means fewer Fireflies, or a later introduction of the Firefly.

 

[tomo pauk]

Maybe make more Spitfire XIIs in place of IXs?

Means fewer Fireflies, or a later introduction of the Firefly.

Agreed 100%.

 

[pbehn]

One thing is that the Allison Mustangs used by the RAF were doing a job that few (if any) others could do that was also very important. Converting Mustangs from Allison to Merlin was considered as was producing Mustangs in UK.

 

[MIflyer]

The Merlin Mustangs had the wing leading edge extensions to accomodate the larger wheels associated with the greater weight, and adding that would have been difficult. The 2 stage Merlin weighed quite a bit more than the V-1710 and the radiator had to be larger as well.

 

[tomo pauk]

The Merlin Mustangs had the wing leading edge extensions to accomodate the larger wheels associated with the greater weight, and adding that would have been difficult. The 2 stage Merlin weighed quite a bit more than the V-1710 and the radiator had to be larger as well.

The LE extensions were introduced with the P-51D. It was capable for 2 x 1000 lb bombs, and was with fuselage tank from day one - neither of the features I've suggested for the Mustang X.
P-51B and C were still with 'legacy' wing shape from the A, with smaller 'kink' and wheels.

 

[MIflyer]

A more reasonable scenario would be why not put the V-1650-1 of the P-40F in the Mustang starting with the Mk IA. The two speed supercharger alone would improve the Mustang a great deal and give us a 1000 mile range 400 MPH fighter, unlike the P-40, where it did not do that much good.

 

[tomo pauk]

A more reasonable scenario would be why not put the V-1650-1 of the P-40F in the Mustang starting with the Mk IA. The two speed supercharger alone would improve the Mustang a great deal and give us a 1000 mile range 400 MPH fighter, unlike the P-40, where it did not do that much good.

I'm all for the V-1650-1 in the nose of Mustangs of 1942-43. Even the Merlin 45, 47 or 50 work for the Mustang Is already in the RAF service.
With that said - the wholesale effort wrt. Mustang X is rarely discussed, thus this thread.

 

[drgondog]

It is impossible in your timescale.

Idea floated 30 April 1942. Authorised 12 August. Prototypes first flew Oct-Dec 1942. Then it would have needed productionised (there were variations between the various conversions), facilities and resources found to do the conversions etc etc in wartime Britain workingbto the max. It would be lucky if it could even have been started production by mid 1943 when you want 200+ in service. And you have a non standard aircraft type with a mix of US and British parts.

Agreed but even if the scope were limited to just existing Mustang I and IA airframes, the questions and solutions are too complex to justify that project.
1.) NA-73/83/91 airframe cooling inadequate for Merlin 60 series thermal loads. The R-R conversion retained the existing glycol/oil cooler concept, but deviated from NAA practice of integrating aftercooling and Coolant radiators into a single frame/two matrix design, whereas R-R stuck the aftercooler under the carb and built a P-40 type cowl.
2.) Wings needed replacement with NA-99 (P-51A) wing to incorporate the wing pylon, internal fuel feed. Structural changes to spar and internal routing was probably too difficult time/labor related to be practical.
3.) Delivery projections of late 1943 for factory P-51B/C probably out paced reasonable forecasts for replacement of Mustang X versions.
4.) Only possible replacement parts were from existing Mustang X
5.) only conceivable performance advantage over local Spit IX = range and dive, perhaps a little dash speed. To achieve P-51B/D roll performance more structural mods required for aileron loading at 12/15 degrees over 10 degree wing.

Meanwhile US attache in London advised of possibility in May. 25 July conversion of 2 aircraft by North American authorised by USAAF. Order for 400 placed August based on performance estimates. Prototype P-51B flies 30 Nov. Production starts May 1943 and say usual 4-5 months from factory door to front line. RAF equips its first squadron in Dec 1943 the month after the first US P-51B unit arrives in Britain.

Ewan - the 'keel' for the P-51B-1-NA was set in December and production parts/assemblies were in process in January, 1943. The first P-51B-1-NA 43-12093 was complete last week of March, 1943, save installed 1650-3 which was still being 'fixed' at Packard. Approximately 20 P-51Bs were complete when the first flight of P-51B-1-NA #1 occurred in first week of May.

Materiel Command cleared NAA Dallas in mid 1942 to wind down Dallas B-24 production and green lighted P-51C production in October 1942, along with new P-51D-5-NT contract in April 1943. Point to make - Tooling transfer planning for Dallas began as early as March 1943 but the first P-51C took till August to produce #1 - even with jump start of Inglewood Mustang project engineer Bowen as Dallas Plant Manager - and spares allocations while Dallas began making its own parts .

NAA was solicited by BAM/R-R to license produce P-51B airframes in England and it took approximately a year of study to conclude, a.) impractical to ship tooling of P-51B, build facilities, hire and train engineer/production people and begin production earlier than mid 1944. Using Australia Mustang as a rule of thumb, the estimate was probably optimistic.

I really don't see it as being worth the effort when the aircwar in the early part of 1944 is over northern France. By late 1944 when Bomber Command begins daylight raids there are enough P-51B/C/D/K available to allow conversion of many RAF squadrons.

Edit N.A. production is on a line that was already up and running and as a follow on to the A-36.

NAA was parallel producing A-36, P-51A and P-51B in 1st qtr 1943, into June 1943.

I guess the fundamental questions (for me) are:
1. Why re-invent a lesser version of Merlin Mustang already in production just months after first flight of AL-975G?
2. Why invest in a Mustang version with no discernable performance advantage, other than range, over the Spit IX with same engine?
3. For Army Co-op role, is Mustang X range potential (Mission footprint) with Merlin and modified wing (labor/time) enough to justify half of the existing Mustang I fleet non-operational?
4. The 1650-1 equipped Mustang I makes even less sense, than 1650-3. The performance envelope versus Spit IX is truncated at 18-20K, requires nearly the same effort to re-design cooling and powerplant installations, loses much commonality in spare parts -

IMO - Except for high altitude escort, the P-51A/Mustang II would be a superior performer (vs Mustang X) for RAF doctrine bomber escort (light, medium or heavy)/tactical mission profiles. with further advantage that it was production airplane in potential quantities greater than Mustang I/X fleet and did Not draw on Merlin 61 production anywhere.

 

[tomo pauk]

I guess the fundamental questions (for me) are:
1. Why re-invent a lesser version of Merlin Mustang already in production just months after first flight of AL-975G?
2. Why invest in a Mustang version with no discernable performance advantage, other than range, over the Spit IX with same engine?
3. For Army Co-op role, is Mustang X range potential (Mission footprint) with Merlin and modified wing (labor/time) enough to justify half of the existing Mustang I fleet non-operational?
4. The 1650-1 equipped Mustang I makes even less sense, than 1650-3. The performance envelope versus Spit IX is truncated at 18-20K, requires nearly the same effort to re-design cooling and powerplant installations, loses much commonality in spare parts -

I'll take a stab:
1. Could you reformulate?
2. Range is not just a nice-to-have thing, but the key feature, and was lacking from WAllied fighters in the ETO in 1943. Thus Mustang.
3. Defeating Germany requires defeating Luftwaffe. Army co-op assets can't do it, not in 1943. My goall is that all surviving Mustang RAF has is turned into Mustang X.
4. V-1650-1 is second best choice (together with other 1-stage Merlins). Advantage is that there is far more of V-1650-1s available, than the 2-stage Merlins.

 

[drgondog]

I'll take a stab:
1. Could you reformulate?
2. Range is not just a nice-to-have thing, but the key feature, and was lacking from WAllied fighters in the ETO in 1943. Thus Mustang.
3. Defeating Germany requires defeating Luftwaffe. Army co-op assets can't do it, not in 1943. My goall is that all surviving Mustang RAF has is turned into Mustang X.
4. V-1650-1 is second best choice (together with other 1-stage Merlins). Advantage is that there is far more of V-1650-1s available, than the 2-stage Merlins.

My take:
Mustang I and Lightning were ready to go in quantity for 1943. One was superior under 15K, the other to 40K. But, before May 1942 the AAF had ACCEPTED only the two XP-51 and had just finally contracted for A-36 and just started the experimental XP-51B. There were no more orders for Mustang I and IA so the logistics pipeline for spares and parts had a very finite life.
Through mid 1943, the Mustang (A-36, P-51A and P-51B) was Not contemplated by any senior AAF officer for anything but tactical recon and fast low level attack.
The P-51A, B and A-36 were in serial production March 1943.
Defeating LW requires high performance and bomber range at bomber altitudes - of US 8th AF, or RAF switches back to daylight bombing as bait for available escorts. The only escort fighters with combat radius > 150 mi is Mustang I and P-38 G/H in early 1943. Mustang could extend existing escort/PR range w 2x50 cal and use of 27gal wing auxiliary tanks delivered as kits.
Mustang I could have delivered in escort role for many light/medium bomber attacks but rarely used. A-36 and P-51A were used because of much more range combined with firepower.

The proposed problem to be solved by RAF/R-R conversion of Mustang I/IA by converting to Merlin 61 would be to achieve same high altitude performance of Spit IX but with greater range - but why? There was no pressing RAF mission in late 1942 to propel a decision to rotate portions of the Mustang I fleet out of combat ops and draw on Merlin 61s at the expense of Spit IX which was very important 'solution' to Fw 190.
Next is question of 'time to combat' for new "Mustang XI". Assuming decision made at end of 1942 to start conversion. Knowing that first P-51B is also starting in production, and P-51A with built in combat tank/pylon and better engine is also in serial production, isn't a better approach to contract for either or both (which RAF did)? Suspect that RAF squadron level deployment of achieved wing and powerplant modified Mustang XI was about that of P-51B-1.

Last, but not least - after conversion at great expense and share of critical engine resources (Spit IX Merlins), is RAF giving US the resulting product? Equally questionable, is AAF going to replace P-47C/D with the new ship (now Hybrid NAA/Brit) with questionable logistics for training and replacement and engineering to respond to change requests?

 

[tomo pauk]

Mustang I and Lightning were ready to go in quantity for 1943. One was superior under 15K, the other to 40K. But, before May 1942 the AAF had ACCEPTED only the two XP-51 and had just finally contracted for A-36 and just started the experimental XP-51B. There were no more orders for Mustang I and IA so the logistics pipeline for spares and parts had a very finite life.
Through mid 1943, the Mustang (A-36, P-51A and P-51B) was Not contemplated by any senior AAF officer for anything but tactical recon and fast low level attack.
The P-51A, B and A-36 were in serial production March 1943.

All fair, I was trying to have RAF being the primary Mustang X's user.
AAF will soon change their mind.

Next is question of 'time to combat' for new "Mustang XI". Assuming decision made at end of 1942 to start conversion. Knowing that first P-51B is also starting in production, and P-51A with built in combat tank/pylon and better engine is also in serial production, isn't a better approach to contract for either or both (which RAF did)? Suspect that RAF squadron level deployment of achieved wing and powerplant modified Mustang XI was about that of P-51B-1.

Having a better engine than it was the V-1710-39 does not solve the problems of fighting above 20000 ft. The P-51A is also very late, 1st combat being in September of 1943.
P-51A's engine is 3rd best Allied V12, after the 2-stage Merlin and 1-stage Merlin (disregarding the turboed V-1710).
P-51B is not starting production by late 1942, not even the P-51A is in production yet. There are no 2-stage Merlins in series production at Packard yet, grand total of 9 V-1650-3s was produced before May of 1943.
I'd suspect the RAF deploying the 1st squadron of Mustang X by Spring of 1943 for the RAF.

The proposed problem to be solved by RAF/R-R conversion of Mustang I/IA by converting to Merlin 61 would be to achieve same high altitude performance of Spit IX but with greater range - but why? There was no pressing RAF mission in late 1942 to propel a decision to rotate portions of the Mustang I fleet out of combat ops and draw on Merlin 61s at the expense of Spit IX which was very important 'solution' to Fw 190.

Better high-altitude performance than the Spitfire XI, not the same. 20-30 mph extra is not a small thing back in 1943.
Granted, RAF has no doctrine of really long-range escort in 1942, even if they will be aware of usability of having long-range fighters now that N. Africa and SE Asia are in a major war.

Last, but not least - after conversion at great expense and share of critical engine resources (Spit IX Merlins), is RAF giving US the resulting product? Equally questionable, is AAF going to replace P-47C/D with the new ship (now Hybrid NAA/Brit) with questionable logistics for training and replacement and engineering to respond to change requests?

No, RAF does not give the AAF the resulting product.
The product is used to escort the US bombers to the much greater distances than it was the case with Spitfire XIs in 1943.

 

[drgondog]

Having a better engine than it was the V-1710-39 does not solve the problems of fighting above 20000 ft.

Agreed - which is why I made the distinction between high altitude escort not feasible - but everything else on the table for Brit and US medium to low altitude long range strikes.

The P-51A is also very late, 1st combat being in September of 1943.

Yes, in CBI along with A-36. A-36 in ops July but less desirable as ecort (still used as such in CBI). I question the combination of basically hand fitting changes to Mustang I to Mustang X, then combine to retrofit with kits or obtain P-51A spares for wings to deliver combat pylons - to deliver capable but substandard (vs P-51B) high altitude ops in ETO by winter 1943/44. If the judgment is that four squadrons of Mustang XI is tactically suitable for ops by RAF in support of 8th AF, is there a higher value mission for it? The crucial window for 8th AF fortunes was between July and October - then a re-start in January 1944.

The necessary wing changes give me pause. It took initiation of prototype wing pylons being tested in NA-83 starting (after wing mods for 500 pound bomb) as AM118 served as prototype test vehicle. The good news is that NAA could share the results and detail design changes to proceed on both A-36 and P-51A wing for production incorporation into A-36 (Oct) and P-51A (Feb) first flights. There were changes including skin thickness, doublers, etc on AM-118 to generate the production P-51A wing plus spares beginning in December 1942. R-R and RAF were deep into flight testing and trouble shooting Mustang X after P-51A first flew as a production article. And yes, the P-51B was absolutely limited by availability of Packard 1650-3, a I noted. But the airframe was complete, save engine installation, instrument hook ups and test runs at the end of March 1943.

P-51A's engine is 3rd best Allied V12, after the 2-stage Merlin and 1-stage Merlin (disregarding the turboed V-1710).
P-51B is not starting production by late 1942, not even the P-51A is in production yet. There are no 2-stage Merlins in series production at Packard yet, grand total of 9 V-1650-3s was produced before May of 1943.
I'd suspect the RAF deploying the 1st squadron of Mustang X by Spring of 1943 for the RAF.

I would marginally hold out hope for a squadron of Mustang X by May/June, but a.) absent field trials and inevitable changes and mods, and b.) absent wing pylon/fuel plumbing modifications to every wing intended for medium range escort. The plus for this approach is engine availability which caused a Minimum of 2-3mo delay on P-51B operations

Better high-altitude performance than the Spitfire XI, not the same. 20-30 mph extra is not a small thing back in 1943.
Granted, RAF has no doctrine of really long-range escort in 1942, even if they will be aware of usability of having long-range fighters now that N. Africa and SE Asia are in a major war.

Agreed, but absent a national commitment for long range daylight support of 8th AF, why devote precious resources and talents to parallel develop a substandard version of the production P-51B-1 scheduled for ops only a couple of months after earliest possible Mustang "XI".

No, RAF does not give the AAF the resulting product.
The product is used to escort the US bombers to the much greater distances than it was the case with Spitfire XIs in 1943.

I have the same question.

That said, it seems intuitive that a.) RAF very much liked its bastard stepchild, and b.) wished to build them in England, and c.) went to the trouble of formally requesting from NAA a plan to build the Merlin Mustang in England - where presumably engine supply would not be an issue.

It seems equally intuitive that the final solution selected was the best - let NAA produce high quality/hi-volume/high performance models and buy them?

 

[tomo pauk]

Yes, in CBI along with A-36. A-36 in ops July but less desirable as ecort (still used as such in CBI). I question the combination of basically hand fitting changes to Mustang I to Mustang X, then combine to retrofit with kits or obtain P-51A spares for wings to deliver combat pylons - to deliver capable but substandard (vs P-51B) high altitude ops in ETO by winter 1943/44. If the judgment is that four squadrons of Mustang XI is tactically suitable for ops by RAF in support of 8th AF, is there a higher value mission for it? The crucial window for 8th AF fortunes was between July and October - then a re-start in January 1944.

IIRC the A-36s were used as escort for B-25s in MTO, too.
The higher-value missions might be providing the long-range escort for the heavies in second half of 1943.

Agreed, but absent a national commitment for long range daylight support of 8th AF, why devote precious resources and talents to parallel develop a substandard version of the production P-51B-1 scheduled for ops only a couple of months after earliest possible Mustang "XI".

Resources and talent will be devoted by the British companies, not by NAA. British already have prototypes flying in Autumn of 1942, unfortunately, there was no follow-up by them.

That said, it seems intuitive that a.) RAF very much liked its bastard stepchild, and b.) wished to build them in England, and c.) went to the trouble of formally requesting from NAA a plan to build the Merlin Mustang in England - where presumably engine supply would not be an issue.

It seems equally intuitive that the final solution selected was the best - let NAA produce high quality/hi-volume/high performance models and buy them?

P-51B - excellent as it was - was not a solution for 1943. Thus it does not check the box for question #1 asked to a weapon of war: 'is it actually available?'.
A non-ideal Mustang X is still a far better asset than the Spitfire XI for the needs of ETO in 1943, at it can be had for operations in that year.