RAF P-51 MK1a's, preferably RCAF

[fubar57]

Good stuff. I was always curious as to why a front line squadron would have yellow codes

 

[Dan Fahey]

The P-51A's single stage single speed supercharger was set up for best performance at higher altitude than the earlier versions, which varied from about 5000 ft for max speed to about 15,000 ft for the Mk1 and Mk1A. The result was that the P-51A had about the same top speed at 20,000 ft as the Spitfire IX, but above that performance would have dropped off, like it did with the FW-190A .

But of course while its top speed may have dropped off, the Spit IX's Merlin 60 series was producing plenty of power all the way up to 30,000 ft.

A two speed single stage supercharger would have been dead easy to do for the V-1710. Installation of the V-1650-1 with its two speed sngle speed supercharger, would have produced really sparkling performance and would have done the Mustang a hell of a lot more good than it did the P-40F. Neither would have been able to touch a two speed Merlin equipped P-51B, especially at high altitudes, but they still would have beat the hell out of anything else the USAAF had and could have been in production no later than around Sep 1942 - the same month where they found out what the XP-51B could do.

What I find interesting was the Allison was the better stronger more reliable engine. Less expensive . Easier to build. Easier too Rebuild. When the engines sorted out the P38 later Turbo Engines they were getting 2000hp. The engineers never did build a good 2 stage 2 speed supercharger. Not sure if it was arrogance but still stiff armed British advice for good fixes on what they had.

 

[MIflyer]

The V-1710 was lighter than the V-1650 and was considered to be more reliable, even by the RAF. It also had far fewer parts and was easier to repair, in part since the accessory case and gearcase could be separated from the block, unlike the Merlin where it was all one piece. To change the direction of prop rotation on the Allison required changing only one gear; the Merlin required a whole different engine to do that. The V-1710 had a Bendix pressure carb that injected fuel into the supercharger; that prevented the Lean Cut/Rich Cut problem of the Merlin with the float type carb.

And they not only did not develop a two speed two stage supercharger that fit right on the case like the Merlin 60 series, they also never even built a two speed single stage supercharger, That meant that at the time of Pearl Harbor the V-1710 was behind the times; everybody else was already doing that or planning to in the immediate future.

 

[pbehn]

The V-1710 was lighter than the V-1650 and was considered to be more reliable, even by the RAF. It also had far fewer parts and was easier to repair, in part since the accessory case and gearcase could be separated from the block, unlike the Merlin where it was all one piece. To change the direction of prop rotation on the Allison required changing only one gear; the Merlin required a whole different engine to do that. The V-1710 had a Bendix pressure carb that injected fuel into the supercharger; that prevented the Lean Cut/Rich Cut problem of the Merlin with the float type carb.

And they not only did not develop a two speed two stage supercharger that fit right on the case like the Merlin 60 series, they also never even built a two speed single stage supercharger, That meant that at the time of Pearl Harbor the V-1710 was behind the times; everybody else was already doing that or planning to in the immediate future.

That is just plain silly, are you saying the engines on the Hornet were "completely different"? Can you explain why anyone had the silly idea of putting a Merlin in a P-51?

 

[MIflyer]

The Merlin engines used in the P-82 were different engines and were not interchangeable by slight modification; no doubt they had many common parts. They were lucky to find one for the restored XP-82. In contrast it took changing only a single gear in the V-1710 to switch between a right or left rotation engine

And I thought everyone knew that the reason for putting the Merlin in the P-51 was that it was the only suitable engine around with a two stage two speed supercharger that would fit in a P-51.

 

[pbehn]

The Merlin engines used in the P-82 were different engines and were not interchangeable by slight modification; no doubt they had many common parts. They were lucky to find one for the restored XP-82. In contrast it took changing only a single gear in the V-1710 to switch between a right or left rotation engine

And I thought everyone knew that the reason for putting the Merlin in the P-51 was that it was the only suitable engine around with a two stage two speed supercharger that would fit in a P-51.

The P -82 used Allison engines didn't it? Since the war was over the USA looked more favourably on a home made engine as far as I am aware. The de Havilland Hornet used contra rotating Merlins, and seems to have done rather well in the performance department. I don't think Wiki is the bees knees in accuracy but here for your perusal.... Like most versions of the P-51 Mustang, the first two prototype XP-82s as well as the next 20 P-82B models were powered by British-designed Rolls-Royce Merlin engines, re-engineered for increased durability and mass-production, and built under license by Packard. These provided the fighter with excellent range and performance; however, the Army had always wanted to give the Twin Mustang a purely American and stronger engine than the foreign-designed P-51's V-1650 (built at Packard plants, dismantled after the war). In addition, the licensing costs paid to Rolls-Royce for each V-1650 were being increased by Britain after the war. It therefore negotiated in August 1945 with the Allison Division of the General Motors Corporation for a new version of the Allison V-1710-100 engine.[1] This forced North American to switch subsequent production P-82C and later models to the lower-powered engines. It was found that Allison-powered P-82 models demonstrated a lower top speed and poorer high-altitude performance than the earlier Merlin-powered versions.

 

[Dan Fahey]

The V-1710 was lighter than the V-1650 and was considered to be more reliable, even by the RAF. It also had far fewer parts and was easier to repair, in part since the accessory case and gearcase could be separated from the block, unlike the Merlin where it was all one piece. To change the direction of prop rotation on the Allison required changing only one gear; the Merlin required a whole different engine to do that. The V-1710 had a Bendix pressure carb that injected fuel into the supercharger; that prevented the Lean Cut/Rich Cut problem of the Merlin with the float type carb.

And they not only did not develop a two speed two stage supercharger that fit right on the case like the Merlin 60 series, they also never even built a two speed single stage supercharger, That meant that at the time of Pearl Harbor the V-1710 was behind the times; everybody else was already doing that or planning to in the immediate future.

The Bendix Pressurized Carb is what today is called a FI Throttle Body. It was used on the Merlin and Allison. It did not require special very high pressure fuel pumps like the German Direct Mechanical Injection. It was also more forgiving to tune with the highly Leaded Fuels. The GM FI engines from 50s and 60s had a lead crystallization issue on the injector tips making tuning maintenance a pain. Unless you use the Amoco White 100 octane gas.

Not sure the Mechanics worried too much about the tuning issues as the planes probably did not survive more than 200 hours in a hot combat area.

 

[Bernhart]

Richard Rohmer - Wikipedia Flew the recon mustangs on D-day for the RCAF

 

[nsmekanik]

First off I'd like to thank Mr.Ford for his efforts and taking the time to share his insights with us here and elsewhere on the net. I really do appreciate the input from everyone, what all of this adds up to for me is that it sure would be nice if somebody would do up a state of the art kit of this subject, but given the obscurity of the subject matter it's probably not on anyone's radar in the immediate future. The Accurate Miniatures kit is a nice enough kit, but, as has been pointed out else where, would need a number of corrections. so I've decided to go with a "museum quality" build, by which I mean "will give the viewing public a general idea of what something may have looked like". The one area I find a bit off putting though is the camera mount, aside from the picture that's already been posted, are there any other pics and or drawings of that area?

 

[ColFord]

If you go to the Imperial War Museum collections, photographs page as per the link given at the end of this post, and enter individually the following photo collection reference numbers, it will bring up a number of photos of the camera mounts and cameras used in RAF Mustangs covering the period 1943-1944. The RAF mount as eventually standardised, was fairly simple.
CH17415
CH13455
CH20403
H28781
H28782
FRE14828
FRE14825

Photographs

 

[P-39 Expert]

The V-1710 was lighter than the V-1650 and was considered to be more reliable, even by the RAF. It also had far fewer parts and was easier to repair, in part since the accessory case and gearcase could be separated from the block, unlike the Merlin where it was all one piece. To change the direction of prop rotation on the Allison required changing only one gear; the Merlin required a whole different engine to do that. The V-1710 had a Bendix pressure carb that injected fuel into the supercharger; that prevented the Lean Cut/Rich Cut problem of the Merlin with the float type carb.

And they not only did not develop a two speed two stage supercharger that fit right on the case like the Merlin 60 series, they also never even built a two speed single stage supercharger, That meant that at the time of Pearl Harbor the V-1710 was behind the times; everybody else was already doing that or planning to in the immediate future.

The two stage mechanical Allison V-1710-93 was in production from April 1943. The hydraulic clutch in the auxiliary stage made impeller speeds infinitely variable automatically limiting manifold pressure making a two speed supercharger unnecessary. This engine could have been used in P-39s, P-40s and P-51s. Studies also included it's use in the P-38. However none of these planes received this engine.

Having a single speed in the V-1710 did not impede it's performance. The single speed was high gear, overboosting at takeoff and low altitudes was eliminated by throttling in the earlier engines and by the automatic manifold pressure regulator (autoboost) in later models after mid-'42.

 

[MIflyer]

Well, by overboosting as a result of optimizing the supercharger speed for the higher altitudes, that limited the engine's power at lower altitudes. It would have been a trivial engineering effort to put a two speed supercharger in the single stage supercharged V-1710's, and enabled both a lower altitude optimum point and a higher altitude one as well.

The automatic manifold regulator interfered with the turbo control and was removed in the field on the F-5 recon aircraft, which needed smoooottthhh operation in order to get good pictures.