Superchargers?

[rinkol]

Fine points there.
We might see that failure of the IV-1430 was never mentioned in the article, yet Arnold's condemning comments about US engines' manufacturers can be read easily:



In late 1942, both UK and Germany were trying to develop the engines that were neither small, nor light (Sabre, Griffon, Centaurus, DB-603, Jumo 213/222, BMW-802). The USAC/USAF never put much faith before 1942 in two-stage engines either - why all of the sudden accusing the manufacturers for not designing the stuff the main costumer isn't asking for? If there was no USN and P&W cooperation, the P&W 2-stage ('highly supercharged') engines would've likely never existed. Even Wright produced 2-stage variant of the R-2600, though just as prototype (prototypes?).
Contrary to that, USAC/USAF favored turbo, and that does not mean small, and by extension, does not mean light. Insistence for turbo meant that engine-stage compressors were of modest size, too.



That is dated as of "3 November 1941".
The R-2800 was at that time (and any other time) a far better engine than BMW-801. In late 1941, the lack of fuel injection was not a thing holding back the R-2600, but a better layout of exhaust, that was solved mid-war. The 801 was somewhat smaller, but R-2600 was far more reliable, despite some Curtiss muddling.

Here is the reply (dated 11 December 1942) from P&W to the Arnold's accusations of 14 October 1942, a footnote from same web site:

The BMW 801 enjoyed an inflated reputation early in the war due to the reputation of the FW 190. Certainly, the FW 190 engine installation was advanced in some respects and fuel injection did avoid problems being encountered with larger engines, such as mixture uniformity.

It may be that Arnold was well aware of the shortcomings of the US engines, both real and imagined, while being unaware of the growing difficulties the Germans were finding themselves in.

 

[tomo pauk]

I'm not sure how one can be aware of imaginary shortcomings
Why the free world owes plenty to Arnold and NACA, I'll state this again:
Arnold did not, at least not what is reported on the article, said that Army was betting on some of the wrong horses. He does not acknowledge that Navy was right to support 2-stage engines development. He either does not know, or won't admit that R-2800 is better than BMW-801. He does not remeber that Army was pushing for turbocharged engines, that equates with low-capability engine-stage superchargers. Forgets that Allison/GM was blackmailed to forget 900 000 US$ for the development of the V-1710.
The article drums Arnold's accusations and requests without any critical distance. The P&W's rebuttal is posted as a footnote, instead just after Arnold's accusation. It claims that Merlin Mustang was the 1st US high-altitude fighter. It claims that V-1710 have had "the basic flaws in the engine's design", not because that is backed with facts and figures, but because someone says so. When someone says that V-1710 was tested/tried to improve with "water injection and supercharging" - that implies that V-1710, as-is, was devoid of a supercharger. The article is silent about the dead-end engines (Continental, Lycoming, Chrysler) that Army was wery keen of. They also seem unaware (at least going by the article) that R-2800 was better engine than BMW-801, let alone that R-2800 was also available in 2-stage and turbo flavor. Ditto for V-1710 (along with water injection) and R-1830.

 

[Balljoint]

When an agency such as NACA writes its own history there's going to be a good bit of puffery and over claiming. What they say about others and inadvertently is more important. Arnold is probably correct that the commercial engine manufacturers offered essentially commercial engines to the military -that's what they know not some devious plot. Since the DC-3 wasn't pressurized, it's not surprising that supercharging, and particularly turbo charging, wasn't their area of expertise. I expect that the Wright engineers had a good bit of work to do to implement the turbo after NACA's proof of concept. Arnold was a bomber man so he should have been overjoyed with the B-17 engine wise.
The Allison issue strikes me as a bit cryptic. Did Arnold want a supercharged Allison so he could have a USAAF interceptor like the Spit or BF-109, or was he starting to see the need for an escort fighter to save the daylight bombing doctrine? I see nothing to suggest that the promise of the P-51 was at all linked to the Allison supercharger request. But maybe there's a bit of Arnold's metamorphosis from the bombers will get through to calling for a long range escort in the request. It should have been easier to tool up for an Allison supercharger –perhaps with help from R-R- than to respec the Merlin and tool up for the entire engine.

 

[Shortround6]

According to others (who may be equally biased) the Army started the whole "hyper" engine thing back in the very early 30s. They had been fooling with turbo superchargers since the 20s (GE and Dr Moss had been fooling with them since WW I) and there were a number of experimental or small batches (3-5) of aircraft equipped with turbo chargers for service testing. This 'series' ended with the 50 P-30A fighters equipped with turbochargers ONLY (there was NO engine driven supercharger) delivered in the summer of 1936. These were also the last of the Curtiss liquid cooled V-12 Military engines which dated back to the mid 20s. The Turbo 'merely" allowed sea level power to be maintained to much higher altitudes and very little boost in manifold pressure was used.
Army thinking was that air cooled engines would NOT cool properly in the thinner High altitude air, only 1/2-1/3 of the mass of air flowing over the fins so liquid cooled engines were essential to a high altitude bomber force. Of course at this time a bomber wing could be 4-5 feet thick so there was a lot of interest in flat engines that could be 'buried" in the wing for less drag.
Obviously some of these Army requirements/wishes would have lead to engines that were NOT really marketable on the commercial scene.
Wright and P&W both increased the amount of fin area per cylinder by leaps and bounds during the 1930s. Better baffles to force more of the air that entered the cowling to pass close to the cooling fins also helped. They finally figured that air that passed more than 3/16 of inch away form the fins did no good at all.

Army also hoped that the flat engines would fit in the wings of smaller aircraft than "large" bombers but had to give up the idea of buried engine as wings got thinner and thinner. Also the engines were never quite as flat as the Army hoped. Things like intake manifolds and accessories like generators and pumps tended to bulk them up a bit.

The "hyper" engines were going to require both high boost and high rpm to get the desired output. Army was trying for 1 hp per cubic inch of displacement. They were trying for this bench mark (or setting this goal) when production engines were producing 1/2 hp per cubic in even for liquid cooled engines. It is little wonder than the commercial engine builders didn't want to play this game.

 

[gjs238]

NA had some vague ideas but were trying to survive against official obstruction from the USAAF (it's only customer really was the British).

Just to clarify, you mean NA's only customer for the P-51?
In contrast to, say, the B-25.

 

[Koopernic]

"They also seem unaware (at least going by the article) that R-2800 was better engine than BMW-801, let alone that R-2800 was also available in 2-stage and turbo flavor. ".

Why would you say that? The BMW 801 was an R-2560 engine, some 8.1% smaller than the PW-R2800. It's progress in development shows it was yielding 2200 metric horsepower by the end of 1944 while a new version with a stronger crankshaft was yielding 2580hp. The R-2800 relied on either 110/150 octane fuel or 100/130 fuel with ADI (water/ethanol injection) to get 2800hp on the R-2800-57C. The R-2800 was effectively redesigned/re-engineered twice, once in 1940 and again for the C series. What we are seeing is the effect of smaller volume, inferior fuel and perhaps a few months lag in BMW introducing its innovations which is to be expected given the bombing campaign at this stage.

Allied 100/130 fuel was at least 102/130 while German C3 fuel was around 96/125 (they fiddled with it several times, started out around 93/115 at the BoB)

I really don't seem much difference at all.

 

[rinkol]

According to others (who may be equally biased) the Army started the whole "hyper" engine thing back in the very early 30s. They had been fooling with turbo superchargers since the 20s (GE and Dr Moss had been fooling with them since WW I) and there were a number of experimental or small batches (3-5) of aircraft equipped with turbo chargers for service testing. This 'series' ended with the 50 P-30A fighters equipped with turbochargers ONLY (there was NO engine driven supercharger) delivered in the summer of 1936. These were also the last of the Curtiss liquid cooled V-12 Military engines which dated back to the mid 20s. The Turbo 'merely" allowed sea level power to be maintained to much higher altitudes and very little boost in manifold pressure was used.
Army thinking was that air cooled engines would NOT cool properly in the thinner High altitude air, only 1/2-1/3 of the mass of air flowing over the fins so liquid cooled engines were essential to a high altitude bomber force. Of course at this time a bomber wing could be 4-5 feet thick so there was a lot of interest in flat engines that could be 'buried" in the wing for less drag.
Obviously some of these Army requirements/wishes would have lead to engines that were NOT really marketable on the commercial scene.
Wright and P&W both increased the amount of fin area per cylinder by leaps and bounds during the 1930s. Better baffles to force more of the air that entered the cowling to pass close to the cooling fins also helped. They finally figured that air that passed more than 3/16 of inch away form the fins did no good at all.

Army also hoped that the flat engines would fit in the wings of smaller aircraft than "large" bombers but had to give up the idea of buried engine as wings got thinner and thinner. Also the engines were never quite as flat as the Army hoped. Things like intake manifolds and accessories like generators and pumps tended to bulk them up a bit.

The "hyper" engines were going to require both high boost and high rpm to get the desired output. Army was trying for 1 hp per cubic inch of displacement. They were trying for this bench mark (or setting this goal) when production engines were producing 1/2 hp per cubic in even for liquid cooled engines. It is little wonder than the commercial engine builders didn't want to play this game.

It is a valid point that there was considerable logic behind the Army's thinking. Things went wrong with practical details. The idea of burying engines in the wings of bombers to reduce drag sounded good, but in practice led to structural and maintenance problems and complicated the task of finding space for the landing gear and fuel. Furthermore, as conventional engine installations were improved, the aerodynamic benefits turned out to be more apparent than real.

There would seem to have been a chicken and egg situation when aircraft manufacturers must have recognized the risks involved in having to tailor aircraft designs to engines that might or might not be available in the future and engine manufacturers did not want to invest their resources in specialized projects for which the market was uncertain at best.

There are more recent examples where efforts to develop technologies targeted at military requirements that were perceived to be unique went nowhere - the Very High Speed Integrated Circuit (VHSIC) program in the 1980s and ADA programming languages come to mind.

 

[FLYBOYJ]

Thinking about it it would have been much smarter to ship P-51 shells across to the UK and let RR convert them....since NA took soooo long to produce a fast, but fairly average and buggy plane, with rubbish and unreliable guns and crappy vision (and a tendency to lose tails). RR was far better at that sort of thing and as master of mass production could have (given their clout with the UK Govt, not even Portal would dare to cross swords with RR, though he did quite happily do that with Arnold) converted heaps of them to become superb planes long before they actually did.

NA didn't produce the guns and at least on the initial US order had little decision on what type of guns were used, they just installed them per customer request and the guns were probably "GFE."

NA produced 41,900 T-6s, P-51s and B-25s. Masters of production?

I don't think RR "would have" been in a postion to do an "AIRFRAME" mod to support a Merlin installation on an early P-51 when there were other UK airframe manufacturers more than capable of doing this. Come to think of it, RR was an ENGINE manufacturer (and a damned good one) weren't they??? - not an AIRFRAME manufacturer or mod center.

Just to clarify, you mean NA's only customer for the P-51?
In contrast to, say, the B-25.

Don't forget the T-6...

 

[tomo pauk]

Sorry for the late reply

Why would you say that? The BMW 801 was an R-2560 engine, some 8.1% smaller than the PW-R2800.

Agreed with your numbers.
The aircraft didn't 'cared' whether the prop was turned by a 30, 40 or 50L engine, what it mattered were engine's strong points (power, reliability) and weak points (physical size/drag, weight, consumption).

It's progress in development shows it was yielding 2200 metric horsepower by the end of 1944 while a new version with a stronger crankshaft was yielding 2580hp.

The new version was not yielding anything, apart from what it did on the test bench. The R-2800 was making 3500 HP on test bench, during ww2; nobody was using such power in the war, however.
2200 metric horsepower need to be cut by 75-80 PS for the prop, and then converted into HP. That makes 2090-2095 HP. The R-2800 C series was capable for 2100 HP for take off, no ADI, no 150 grade fuel needed. 1st Corsair with C series engine was delivered in December 1944.

The R-2800 relied on either 110/150 octane fuel or 100/130 fuel with ADI (water/ethanol injection) to get 2800hp on the R-2800-57C.

Let's not make a shortcoming from the capability. The R-2800 was suitable for ADI, the BMW-801 was not (apart from prototypes and one-offs).

The R-2800 was effectively redesigned/re-engineered twice, once in 1940 and again for the C series. What we are seeing is the effect of smaller volume, inferior fuel and perhaps a few months lag in BMW introducing its innovations which is to be expected given the bombing campaign at this stage.

The BMW 801 also received substantial modifications. 1st one was from A/C to D, second one was from D to E and S. The 'F' was like 3rd modification. There is no much point in drawing out a bit smaller displacement as an argument, as covered above.
BMW might want to look at the wasted years of 1939-43, when they were trying to design like 5 new engines, instead to concentrate on the 801.

Allied 100/130 fuel was at least 102/130 while German C3 fuel was around 96/125 (they fiddled with it several times, started out around 93/115 at the BoB)

This might be a 'strawman'. The German fuel was tested by Allies and sometimes found to be between 130 and 140 grade (for rich setting). The BMW 801D was capable for 1.42 ata much of the time (less before Oct 1942), on C3 fuel, while the DB-601/605 and Jumo 211 were capable, in most prolific versions, for same boost pressure on just B4 fuel. It took quite some time for the BMW to up the MAP at 1.62 ata, and, still a further year ahead, and with a new version, to achieve 1.82 ata.
The B series of the R-2800 worked just fine at 150 grade fuel, ie. there was no need for new engine version to achieve greater MAP.

I really don't seem much difference at all.

Difference was most pronounced in 1941, when the A series of the R-2800 makes more power and it is a relaible engine, unlike the 801C. The 801A was further derated, just the 1600 PS take off power was same as the 801C. Once the B series of the R-2800 is available (about Pearl Harbor), the difference is even more pronunced. The restricted 801D is about capable as the 801C. Only after the 801D was cleared for 2700 rpm and 1.42 ata, the power at altitude is in the ballpark, the R-2800 has more power under 16-17000 ft; some 20% more for TO.

The 2-stage R-2800 has no peer in the 801 stable, and that is the main difference. The turbo 801 is a mere footnote in 801 history, unlike the turbo R-2800. Lack of available high-altitude BMWs was keenly felt in 1944, when the Allied fighters powered by 2-stage or turbo engines were unleashed upon the LW in the ETO.

 

[tomo pauk]

Okay, since I have no popcorn handy:

Thank god for Roll Royce then. It was powerful enough and tough enough (under the great Hives) to ignore that nonsense from idiots.

RR saved the day back in BoB era, when thing were far more sticky than in 1944. For the USAF, thank god for Allison and P&W delivering useful engines to power US fighters. Thank god for Dr. Moss and GE for having turbo systems ready by the time US went to war. We might also thank to the USAF, for pushing for turbo R-2800 and licence production of Merlins.

People, especially Americans (who have a talent for reinventing history), underestimate how important RR was to creating the Merlin Mustangs. The USAAF didn't want it, NA had some vague ideas but were trying to survive against official obstruction from the USAAF (it's only customer really was the British). The Air Ministry didn't want it (especially Portal) , MAP didn't want it, there were official instructions from those to RR to NOT DO IT, Hives ignored them and told it team to go ahead... hence the Merlin Mustang X... which was a god send to Arnald trying to get some, against endless US and UK opposition, a decent LR fighter.

RR was indeed very important for the creation of Merlin Mustang. They issued their study in June 1942 about the project involving Merlin 61 in Mustang air-frame. However, you are as wide from the mark as possible about USAFs opposition to it, as well as NAA ideas. USAF gave a contract to the NAA for two XP-78s (= future XP-51B) already in June 1942. Hopefully that is fast enough? NAA received the contract for 400 P-51B-1NA at Aug 26th. Same question.
NAA flew the XP-51B for the 1st time at Nov. 30th 1942; engine overheating cuts the 1st flight short, the radiator and cooling air scoop must be redesigned. Just slap the Merlin on the Mustang I and go your merry way? Don't think so. The 1st conversion in UK flies earlier, in October, and that fight is aborted when a piece of cowling leaves the aircraft.
USAF was ignoring the Allison Mustang, and they can look guilty for that today (NAA successful bidding for A-36 basically saved the program). Contrary to that, Merlin Mustang was made possible much due to USAF and NAA (and RR and some other people in the UK) enthusiasm about it.

To be fair I think NA then stuffed up because it took nearly another year to produce the P-51B... it would have been much better to just slap Merlins into P-51As and get them out of the door fast (like a Spit V to Spit IX thing). So instead of P-51Bs arriving in late '43 in very small numbers could have been lots of P-51x's in say March/April 43... but hey Govt/corporate politics....heck the Merlin X was superior to the (much) later P-51B....at least it had guns that fired....

Again a shot that is loud, but hits away from the target.
It was not fault of NAA that Packard was somewhat late with 2-stage Merlins. By July 1943, the NAA received only 173 Merlins, against 534 air-frames the NAA completed. Slapping the 2-stage Merlin on Mustang I airframe will take time. RR took 3 months for a fastest conversion of the previous Mustang, and how much for the slowest of 5 completed? Things can happen in case radiators are not properly engineered and installed, as seen above. From where the British 2-stage Merlins would come from, and what aircraft won't have them - Spit VII, XI, up-engined Mossie? What was wrong with Govt/corporate politics in case of P-51B? Mustang X (I take it you mean that, not Merlin X) was not superior to the P-51B in any way. You want to go with .30s against Luftwaffe in 1944, if the .50s were that bad? Who managed to kill plenty of LW hardware and pilots in 1st half of 1944? The Mustang I never had fuselage tank installed.

Thinking about it it would have been much smarter to ship P-51 shells across to the UK and let RR convert them....since NA took soooo long to produce a fast, but fairly average and buggy plane, with rubbish and unreliable guns and crappy vision (and a tendency to lose tails). RR was far better at that sort of thing and as master of mass production could have (given their clout with the UK Govt, not even Portal would dare to cross swords with RR, though he did quite happily do that with Arnold) converted heaps of them to become superb planes long before they actually did.

Okay. Let's continue with production of Spitfire Vs, because we're short with 2-stage Merlins. Maybe forget the Mosquito with 2-stage engines? NAA was not guilty a single bit about how much it took to produce P-51B.
Your mud throwing at the Mustang is not worth a reply. Ditto for it's guns. RR was never in airframe business, a conversion of handful of airframes does not equate with major airframe modification company.

added: the Mustang X, as a modification of the Mustang I, was not outfitted to carry drop tanks. So we can forget long range from that one.
The racks, once hopefully installed, will cut 12 mph from 422 mph at 22500 ft (the Merlin 61 was not as powerful as Merlin 63/66, or V-1630-3/-7; how much of the drag was induced by slapped-on intercolers?), so our nifty Mustang X is now as fast as Fw-190A-5 and Bf-109G-2. It is slower than P-47 above 25000 ft.

 

[OldSkeptic]

Okay, since I have no popcorn handy:



RR saved the day back in BoB era, when thing were far more sticky than in 1944. For the USAF, thank god for Allison and P&W delivering useful engines to power US fighters. Thank god for Dr. Moss and GE for having turbo systems ready by the time US went to war. We might also thank to the USAF, for pushing for turbo R-2800 and licence production of Merlins.



RR was indeed very important for the creation of Merlin Mustang. They issued their study in June 1942 about the project involving Merlin 61 in Mustang air-frame. However, you are as wide from the mark as possible about USAFs opposition to it, as well as NAA ideas. USAF gave a contract to the NAA for two XP-78s (= future XP-51B) already in June 1942. Hopefully that is fast enough? NAA received the contract for 400 P-51B-1NA at Aug 26th. Same question.
NAA flew the XP-51B for the 1st time at Nov. 30th 1942; engine overheating cuts the 1st flight short, the radiator and cooling air scoop must be redesigned. Just slap the Merlin on the Mustang I and go your merry way? Don't think so. The 1st conversion in UK flies earlier, in October, and that fight is aborted when a piece of cowling leaves the aircraft.
USAF was ignoring the Allison Mustang, and they can look guilty for that today (NAA successful bidding for A-36 basically saved the program). Contrary to that, Merlin Mustang was made possible much due to USAF and NAA (and RR and some other people in the UK) enthusiasm about it.



Again a shot that is loud, but hits away from the target.
It was not fault of NAA that Packard was somewhat late with 2-stage Merlins. By July 1943, the NAA received only 173 Merlins, against 534 air-frames the NAA completed. Slapping the 2-stage Merlin on Mustang I airframe will take time. RR took 3 months for a fastest conversion of the previous Mustang, and how much for the slowest of 5 completed? Things can happen in case radiators are not properly engineered and installed, as seen above. From where the British 2-stage Merlins would come from, and what aircraft won't have them - Spit VII, XI, up-engined Mossie? What was wrong with Govt/corporate politics in case of P-51B? Mustang X (I take it you mean that, not Merlin X) was not superior to the P-51B in any way. You want to go with .30s against Luftwaffe in 1944, if the .50s were that bad? Who managed to kill plenty of LW hardware and pilots in 1st half of 1944? The Mustang I never had fuselage tank installed.



Okay. Let's continue with production of Spitfire Vs, because we're short with 2-stage Merlins. Maybe forget the Mosquito with 2-stage engines? NAA was not guilty a single bit about how much it took to produce P-51B.
Your mud throwing at the Mustang is not worth a reply. Ditto for it's guns. RR was never in airframe business, a conversion of handful of airframes does not equate with major airframe modification company.

added: the Mustang X, as a modification of the Mustang I, was not outfitted to carry drop tanks. So we can forget long range from that one.
The racks, once hopefully installed, will cut 12 mph from 422 mph at 22500 ft (the Merlin 61 was not as powerful as Merlin 63/66, or V-1630-3/-7; how much of the drag was induced by slapped-on intercolers?), so our nifty Mustang X is now as fast as Fw-190A-5 and Bf-109G-2. It is slower than P-47 above 25000 ft.

Few things.
The P-51A was equipped for drop tanks with options of the 75 or (ferry) 150 US gals ones.
They used the Merlin 65 for the Mustang X since it was similar in performance as the 66 (as used in the LF Mk IX).

Merlins (either XX series or 60 series) had been explored by RR in early 42, but there was no US interest. RR put forward a XX series engined Mustang as an 'interim' model.
Wright field (the US testing area) had very little interest (in fact antipathy) to the Mustang, one that got sent there early on was just left sitting there, while they tested everything else around, it was given the lowest priority.
The other manufacturers naturally pushed their own stuff as the 'solution'.

Within the USAAF there was also considerable opposition to a LR escort fighter, firstly because there was a large school of thought that felt it was unnecessary, secondly because it was thought to be impossible. Arnold swung a bit both ways, though he agreed, at the beginning, that the US bombers would get through all right, he did leave the door open (unlike Portal) for an escort fighter and he had been briefed early on on the prospects for a RR engined one with superior performance (we are talking about mid 42)
So he was primed and far sighted enough, in a sense, for when it all went pear shaped in '43* and RR and NA had done enough background work to prove the viability and production was starting up.

*the 'unescorted bomber' myth was proven to be that ... a myth. And the shortcomings of the P047 and P-38 had by then become apparent.

In a more rational world, without all the opposition, you would have seen Mustang development going something like this:
P-51A - Allison.
P-51B - March/April 42. P-51A with a Packard Merlin XX series, huge improvement in mid altitude performance and easily a match for the 109s and 190s of the time (excepting maybe the 109s at very high altitude), with little or no structural changes. Rear tank optional.
P-51C - Sept-Dec 42. Modified P-51A for fitting with RR Merlins in the UK (since Packard was not up speed on them at that time). Moderate structural modifications, like tail and engine mounts, an interim type. Rear tank fitted. Roughly 420mph class, because of the intercooler drag (still faster than anything else at the time).
P-51D - Early '43. Very similar to the actual P-51B with Packard Merlins (now in full production), probably with better/more guns. Rear tank fitted. 440mph class
P-51E - Early '44, same as the original P-51D, the delay was because of the time needed to develop the technology to make the canopies.

Going by that timeline the USAAF could have had a fair number of Mustang escorts (mostly XX series with some 60 series engined) by late '42, with more 60 series coming on-stream as time went on, at least to the (roughly) 350 mile combat radius (500+ with the rear tank).

 

[tomo pauk]

Few things.
The P-51A was equipped for drop tanks with options of the 75 or (ferry) 150 US gals ones.

RAF's name for the P-51A was Mustang II. The 1st P-51A was accepted in March 1943, 1st combat taking place in Summer of that year. RR was converting the Mustang I, ie. the version without racks.
Compared with Mustang I, the Mk.II have had also a different engine ( a bit more power above 14000 ft, a bit less under ~7000) and different weapon layout. The Mustang Ia was cannon armed, the US designation being P-51.

They used the Merlin 65 for the Mustang X since it was similar in performance as the 66 (as used in the LF Mk IX).

Thanks, I stand corrected.

Merlins (either XX series or 60 series) had been explored by RR in early 42, but there was no US interest. RR put forward a XX series engined Mustang as an 'interim' model.

Part of the problem with USAF and Mustang/XX was of subjective nature, part was of objective nature. Mustang was nobody's 'child', nobody from the USAF brass invested any personal prestige on it, so there were no personal gains in case the project succeeds; that would count under 'subjective'. Objectively, the production of the P-47 was to start in three factories, while P-38 was already in service. The Mustang I, for all of it's qualities, was ill suited for intercepting and killing the perceived bomber threat flying above 20000 ft, and that was the role of USAF's fighter force in 1941/early 1942, at least under the current doctrine. The USAF just started tests of the XP-51 in March 1942 - how realistic is that USAF will agree to the RR's proposal for the Merlin XX before the flight tests of the XP-51 are done?
In the other hand, USAF lost no time in giving their support for the P-51 with 2-stage Merlin, after RR's study of July 1942.

Wright field (the US testing area) had very little interest (in fact antipathy) to the Mustang, one that got sent there early on was just left sitting there, while they tested everything else around, it was given the lowest priority.
The other manufacturers naturally pushed their own stuff as the 'solution'.

Solution means that there is problem. What USAF's problem did you have in mind, for the time between XP-51 arrival at Wright Field and the time the tests were done (ie. between Aug. 24th 1941 and March/April 1942)?
On the other hand, I agree that it was a rather big mistake not to start flight tests as early as Aug 25th 1941.

Within the USAAF there was also considerable opposition to a LR escort fighter, firstly because there was a large school of thought that felt it was unnecessary, secondly because it was thought to be impossible. Arnold swung a bit both ways, though he agreed, at the beginning, that the US bombers would get through all right, he did leave the door open (unlike Portal) for an escort fighter and he had been briefed early on on the prospects for a RR engined one with superior performance (we are talking about mid 42)

Yep, USAF was very much favoring the 'self-defending, high-flying bomber' doctrine by the time they got involved in the ETO.

So he was primed and far sighted enough, in a sense, for when it all went pear shaped in '43* and RR and NA had done enough background work to prove the viability and production was starting up.

I'd again give credit to the USAF, too - their contracts with NAA in second half of 1942 pushed Merlin Mustang on the forefront.

In a more rational world, without all the opposition, you would have seen Mustang development going something like this:
P-51A - Allison.
P-51B - March/April 42. P-51A with a Packard Merlin XX series, huge improvement in mid altitude performance and easily a match for the 109s and 190s of the time (excepting maybe the 109s at very high altitude), with little or no structural changes. Rear tank optional.
P-51C - Sept-Dec 42. Modified P-51A for fitting with RR Merlins in the UK (since Packard was not up speed on them at that time). Moderate structural modifications, like tail and engine mounts, an interim type. Rear tank fitted. Roughly 420mph class, because of the intercooler drag (still faster than anything else at the time).
P-51D - Early '43. Very similar to the actual P-51B with Packard Merlins (now in full production), probably with better/more guns. Rear tank fitted. 440mph class
P-51E - Early '44, same as the original P-51D, the delay was because of the time needed to develop the technology to make the canopies.

Going by that timeline the USAAF could have had a fair number of Mustang escorts (mostly XX series with some 60 series engined) by late '42, with more 60 series coming on-stream as time went on, at least to the (roughly) 350 mile combat radius (500+ with the rear tank).

I'd opt for a more aggressive time line:
- once the deal is struck with Packard, ship a couple of the Merlin XXs from UK and give them to the NAA to incorporate it to the NA-73X (another Merlin is a reserve)
- change the contract, so the Mustang will use Packard Merlins (from British part of Packard contract).
- the first 30 engines will be shipped from the UK
- the 1st dozen of Mustang Is arrive in the UK in late 1941
- the 1st service use is at May 1942
- USAF tests the fighter, and buys 1000 of them
- the version with drop tanks is in production from Autum 1942 on
- in the mean time, the 2-stage version is in the works; RR provides 50 engines in winter of 1942/43

 

[Koopernic]

When talking about aircraft engine performance one has to put dates and altitudes to claims about power. No point claiming that a R-2800 of 1944 was better than a 1942 BMW801.

The basic 1730 hp (metric horsepower) BMW801D one sees mentioned so often is an 1942 engine. The engine produced less prior to that time and more thereafter.

Around that time BMW had worked out that the 'welding' together of the exhaust's of cylinders of 9 + 10 and 5 + 6 into a single was costing 80hp, causing vibration, rough running, damaging spark plugs and injectors. Fixing this by the time the Fw 190A6 came into service one can say:

Power at Sea Level at 1.42 ata, 2700 rpm = 1800hp
Power at 5.8km , 2700 rpm = 1490hp (5.8km = 20000ft)

This is in not inferior to the contemporary R-2800 which has 9.5% higher volume as well as a better fuel, German green dyed fuel C3=96/125 versus allied 100/130 which was 102/130.

The Fw 190A with this engine was faster at all altitudes to 22500ft ft and climbed much better than the P-47.

Between 1942 and 1943 BMW, Focke-Wulf conducted experiments using Fw 190A-4 to improve engine power.

a/ Injection of water methanol into the supercharger, MW-50 to cool intake air so that it contracted and more 'oxygen' was available. T
b/ Simply increasing the pressure going into the engine, from 1.42 ata to 1.68 ata in 2nd gear and 1.57 ata in 1st. Advances in spark plugs, fuels, lubricants
made this possible. This was known as Ladedruckerhöhung. (supercharger pressure increase)
c/ C3 injection into the supercharger of C3 to precool and contract the air in the manner of MW50. The correct term was C3 - Zusatzeinspritzung which means C3 supplementary injection.

C3 injection produced more power than MW50 injection, furthermore it didn't require any additional tankage and the center of gravity issues that would create. There was some minor damage found to the engines pistons from MW50 testing but this was over 30 hours of accumulated running.

It's just not right to claim that the BMW 801 was not suitable for water injection, C3 injection was just better and fewer issues eg adding extra tanks, plumbing, C of G adjustments.

The result of this work meant that in 1944 the Luftwaffe introduced not one but two different boosting systems.

Simple boost pressure increases initially went to the Fw 190A8 series fighters, the approval being in Jan 1944 though it doesn't seem to be coming out of production till june 1944.

C3 injection went to the Fw 190F and G series bombers. C3 injection was more powerful and boosted the speed of the Fw 190G 45km/h when it was carrying 3 x SC250kg bombs. They were essentially uncatachable by soviet aircraft till the LaGG 5 came out.

The two system were also combined. This is still the BMW 801D2 we are referring to here, the engine having incorporated advances from the advanced BMW 801E and BMW 801F programs.

BMW 801D2 1.42 ata 2700rpm
power at sea level 1800 ps metric horse power
Power at 5.8km 1490 ps metric horse power

BMW 801D2 1.57 ata 2700rpm
power at sea level 2060 ps metric horse power
power at 5.9km 1695 ps metric horse power

Allied intelligence completely missed detecting these boost systems for 8 months, the first note being March 1945.
http://www.deutscheluftwaffe.de/arc...steigerung/BMW 801 D Leistungssteigerung.html

Using these systems all the A/F/G variants of the BMW engined Focke Wulf 190 increase climb rates by 27% at 8000m.

Speed of the Fw 190A-8 was 22km/h faster at sea level and 25km/h faster at altitude. When carrying bombs the speed increase was 45km/h.

For C3 injection, when released from 1km limit in Jan 1944.
Before
Fw 190 A-8 644 km/h at 6.3 km and 548 km/h Sea Level.
After
Fw 190 A-8 667 km/h at 6.3 km and 570 km/h Sea Level.

In Imperial
Before
Fw 190 A-8 399.5 mph at 21500 ft and 340 mph Sea Level.
After boost increase
Fw 190 A-8 414.0 mph at 21500 ft and 353 mph Sea Level, in fact you'll find tests showing a 360mph speed at sea level and 414 at altitude.

It's worth looking at What the P-47 was doing at the time. ADI did not make it into service till early 1944. P-47DE04 and P-47RE05 were equipped with tanks and plumbing to inject water but couldn't actually do so. First production were the P47DE10 and P47RE11, the earlier versions had to be retrofitted in the field.

P-47 Performance Tests

P-47D10 with ADI (water injection), cooling cuffs, boosted to 2300hp 56 inches of mercury.
P-47D10 406mph at 20000ft and 333mph at sea level. (This is 10 mph slower than the A8 without boost and 20mph with the A8 with boost)

From this data its clear that the Fw 190A-8 with or without C3 injection boost has a significant speed advantage over the P-47D10 with ADI at altitude up to 22500ft-25000ft.

Furthermore while a Fw 190 might take 14 minutes to get to 30000ft the P-47 would take 20 minutes (Me 109 12 minutes).

P-47 pilots were told not to fight at low altitude. See what non other than Hubert Zemke has to say.

P-47 Thunderbolt Vs. Bf 109G/K: Europe 1943-45 - Martin Bowman - Google Books

Lets look at the introduction of the 2800hp in the late 1944 C series engine using higher levels of ADI boost.

As you can see a Fw 190A-8 with either 1800ps or 2060ps is not disadvantaged in speed to the 2800hp P-47 below 20000ft. Same for climb. The P-47M (which saw service in small numbers) and the P-47N (which never saw service in Europe) don't outclass the Fw 190 till 20000ft.


At this point, October 1944, the Luftwaffe has the Fw 190A9 in service with the more capable BMW801TS engine. The BMW 801D2 used on the A8 has reached its limit and would need new components. There "Q" engine entering service at this time in the form of the TU Power egg but it has the same performance as the D2. The designations are about such things as gun mounts, replacement of electrical controls with hydraulic etc.

The BMW 801TS is also a 2000ps engine but it does not need to use short term emergency boost to achieve that. I is well within its detonation limits without either water injection, c3 injection or rich mixtures. (boost on the D2 was limited to 3 x 10 minute bursts per mission with 10 minutes military power in between). Emergency boost is only added a few months latter and they use MW50 because C3 injection wastes fuel.

The Fw 190A9 without boost is 3mph slower than the A8 with boost at sea level due to its greater weight (due to the engine armoring going from 6mm to 10mm) it is however faster at 22500ft being able to do 414mph.

The BMW 801TS is made out of 801E and 801F components. The 801F was supposed to be in production in early 1944 but the Germans are having factory and tooling problems.

The 801TS does not have C3 injection. In fact it will receive the MW50 injection first tested in 1942 in Luftwaffe service in December/January 1944. I have had documents cited that this produced 2400hp, this 20% increase being made up of a combination of the higher charge pressure of 1.82 ata and the charge cooling/contracting effect of the MW50 but I am reluctant to accept more than 2200hp since I have not seen them.

Either way the 2600hp 801F, whose development was complete was to enter production in early 1945. So the 801F bar a few months would have ended up producing 2600ps while the larger R-2800 produced 2800hp.

I do not accept your statement about German C3 fuel achieving 140 PN. If you can provide a citation I would be overjoyed. I have poured over the allied intelligence files at fischer-trospch.org and there is no evidence that C3 ever reached 140. C3 was continuously tested by the allies. C3 was 96/125 around 1943 and a little more, 97/130 somewhat later in the war. Either way this fuel was never available to the BMW801.

The R-2800 was in some ways inferior to the BMW801. For one the poor speed of the P-47 at low altitude was due to its inferior installation. Kurt Tank didn't put a cooling fan and a tight streamline cowl on for aesthetic reasons.

The fact that low altitude speed of the P-47 with 2800hp was so mediocre points to the inferiority of P-47 aerodynamics since with only 2000hp Fw 190 could keep up with it. The Fw 190 itself was aerodynamically inferior to aircraft such as the P-51, Tempest V, Seafury etc with their laminar flow wings which could delay compressibility drag. Both the Fw 190 and the P-47D/M/N are out of date.

The Fw 190 could use cryogenic GM-1 (nitrous oxide) to match the P-47 engine at altitude and the 115L multipurpose tanks usefulness was improved by C of G changes made possible by the increased weight of the engine. It was a moot given that GM-1 was more likely to be used in the Me 109 and that The Fw 190D13 was promising the same kind of 390-400mph sea level speeds as the Mustang by using brute force of the Jumo 213EB while retaining high altitude ability, a speed likely well beyond the P-47 and its 2800hp R2800. GM-1 was inconvenient given the need to develop a cryogenic handling system, having said that it awkwardness is overstated because the oxygen used in the Fw 190 was also cryogenic. In reality it was too difficult to deploy given the breakdown of the Reich's manufacturing capacity.

There never was a 3500hp C series R-2800 engine in an airframe, that only worked in a test rig force blown by an external supercharger.

 

[Denniss]

Both 1800 and 2050 PS given on that page/document is the pure engine power, not the engine system power. 70 PS for the fan have to be substracted.
The BMW 801 retained the dual-exhaust for cylinders 9/10 in the D-2/Q-2, dunno with the S.

 

[Aozora]

When talking about aircraft engine performance one has to put dates and altitudes to claims about power. No point claiming that a R-2800 of 1944 was better than a 1942 BMW801.

The basic 1730 hp (metric horsepower) BMW801D one sees mentioned so often is an 1942 engine.

Who mentions the 1942 1,730 hp BMW801D so often?

Around that time BMW had worked out that the 'welding' together of the exhaust's of cylinders of 9 + 10 and 5 + 6 into a single was costing 80hp, causing vibration, rough running, damaging spark plugs and injectors. Fixing this by the time the Fw 190A6 came into service one can say:

Power at Sea Level at 1.42 ata, 2700 rpm = 1800hp
Power at 5.8km , 2700 rpm = 1490hp (5.8km = 20000ft)

This is in not inferior to the contemporary R-2800 which has 9.5% higher volume as well as a better fuel, German green dyed fuel C3=96/125 versus allied 100/130 which was 102/130.

What "contemporary" R-2800 are we discussing here? There were several variants, but if we are discussing the R-2800-21 fitted to the P-47D-10-RE it was producing 2,000 hp at all altitudes up to 23,800 ft, after which power started dropping off:

from http://www.wwiiaircraftperformance.org/p-47/P-47D_42-74616_Eng-47-1649-A.pdf

Considerably more than 1,490 hp at 20,000 ft. The reason Tank started designing the Fw 190 B, C D series with alternative engines was because the 801 started running out of puff at 20,000 feet, a considerable disadvantage for a fighter that was supposed to be intercepting high altitude American bombers.

Further down you say the BMW 801D-2 produced 1800 PS which actually = 1,775 hp 1,490 PS = 1,469 hp, so which figures do we go with?

The Fw 190A with this engine was faster at all altitudes to 22500ft ft and climbed much better than the P-47.

The P-47 and the R-2800-21 was designed to fly and fight at high altitudes, at exactly those altitudes at which the BMW 801's power dropped off so rapidly. To claim the R-2800 was somehow inferior to the BMW 801 because the much bigger, heavier P-47 had inferior performance to the Fw 190 below 22,500 feet is a nonsense. These were aircraft designed for different purposes and to different specifications. How did the Fw 190 perform against the P-47 - and P-51B/C/D - above its rated altitude?

Did BMW ever successfully design and build in quantity a BMW 801 with a decent high-altitude rated supercharger or turbo-charger? It was a decent enough engine once the bugs had been worked out?

The R-2800 was in some ways inferior to the BMW801. For one the poor speed of the P-47 at low altitude was due to its inferior installation. Kurt Tank didn't put a cooling fan and a tight streamline cowl on for aesthetic reasons.

The fact that low altitude speed of the P-47 with 2800hp was so mediocre points to the inferiority of P-47 aerodynamics since with only 2000hp Fw 190 could keep up with it. The Fw 190 itself was aerodynamically inferior to aircraft such as the P-51, Tempest V, Seafury etc with their laminar flow wings which could delay compressibility drag. Both the Fw 190 and the P-47D/M/N are out of date.

On the one hand you say the R-2800 was in some ways inferior to the 801, yet you then go on to blame the inferior installation in the P-47, plus the P-47's "inferior" aerodynamics, ignoring the fact that the P-47 could fly and fight at altitudes where the 190 struggled. With only 2,000 hp the 190 could not keep up with the 2,800 hp P-47M's 473 mph maximum speed, nor the P-47D's 432 mph

The Fw 190 could use cryogenic GM-1 (nitrous oxide) to match the P-47 engine at altitude and the 115L multipurpose tanks usefulness was improved by C of G changes made possible by the increased weight of the engine. It was a moot given that GM-1 was more likely to be used in the Me 109 and that The Fw 190D13 was promising the same kind of 390-400mph sea level speeds as the Mustang by using brute force of the Jumo 213EB while retaining high altitude ability, a speed likely well beyond the P-47 and its 2800hp R2800. GM-1 was inconvenient given the need to develop a cryogenic handling system, having said that it awkwardness is overstated because the oxygen used in the Fw 190 was also cryogenic. In reality it was too difficult to deploy given the breakdown of the Reich's manufacturing capacity

You are contradicting yourself by stating that the 190 could use GM-1 to match the P-47 at altitude, but didn't use it because the 109 was more likely to use it and anyway the 190D-13 (built AFAIK in very small numbers) could likely outperform the P-47M/N - the latter statement with no evidence. Both statements show that the BMW powered 190 could not match the P-47's performance at altitude because a) it didn't use GM-1 and b) because the Fw 190D-13 used the Jumo 213 specifically because the BMW 801 was not great at higher altitudes.

 

[ohogain]

For what it's worth;

Supercharger Development in the U.S. During the Inter-War Period

Another set of articles from same site: Superchargers

 

[Shortround6]

Many of us focus a bit too much on the displacement of various engines when arguing over which was better. In reality war had no displacement classes.
Best fighter with engine of 36.1-42 liters?
best fighter with engine of 42.1-46 liters?
best fighter with engine of 33.1-36 liters?

What mattered was weight and drag. How much power for how much weight and how much drag for the installation.

What is also often left out is the service life as that was always a trade off between acceptable power levels and acceptable service life. Russians in particular sacrificed engine life for higher power. How much the Germans did it vs not having certain alloys I don't know but the R-2800 was generally a longer lived engine than the BMW 801. Had the Allies been willing to accept the service life of the BMW 801 one wonders what the power level might have been?

 

[tomo pauk]

When talking about aircraft engine performance one has to put dates and altitudes to claims about power. No point claiming that a R-2800 of 1944 was better than a 1942 BMW801.
The basic 1730 hp (metric horsepower) BMW801D one sees mentioned so often is an 1942 engine. The engine produced less prior to that time and more thereafter.

Nobody was claiming that about the 1944 R-2800s. By the Pearl Harbor attack, the P&W has in production not just the B series of R-2800 with single stage supercharger, but also the two-stage B series (2000 HP for TO, but also 1650 HP at 21-22000 ft, and 1800 HP up to 15500 ft; no ram). link (pdf, ww2 engine production in USA)
The BMW 801D entered service some time in early 1942, but was restricted to 1.35 ata and 2450 rpm, in both supercharger speeds. Ie. it was about as good as the BMW-801C. Following the work to debug the issues, the restrictions were lifted in October 1942.

Around that time BMW had worked out that the 'welding' together of the exhaust's of cylinders of 9 + 10 and 5 + 6 into a single was costing 80hp, causing vibration, rough running, damaging spark plugs and injectors. Fixing this by the time the Fw 190A6 came into service one can say:
Power at Sea Level at 1.42 ata, 2700 rpm = 1800hp
Power at 5.8km , 2700 rpm = 1490hp (5.8km = 20000ft)

Covered by Dennis - the power for the fan need to be deduced from those 1490 PS, meaning 1440 PS was available for the prop at 5.7 km. Similar goes for supposed 1800 PS for power at 0.6 km; the take off power (ie. at SL) was at ~1700 PS. The engines were using 'regular' settings already with later examples of Fw-190A-3. Data from flight manual for the 190A-5: pic.
Table for different power settings and speed values; please note the interesting inscription saying 'an Luftshraube PS', or, roughly, 'power (in PS) available for propeller':

This is in not inferior to the contemporary R-2800 which has 9.5% higher volume as well as a better fuel, German green dyed fuel C3=96/125 versus allied 100/130 which was 102/130.

Covered above, re. 1st part. The German C3 fuel could use a dedicated thread; it took quite some time for the BMW-801 to fully use even the 125 PN rich rating anyway.

The Fw 190A with this engine was faster at all altitudes to 22500ft ft and climbed much better than the P-47.

Not sure why out of sudden the P-47 here - should we compare a tiny Fw-190 with it?

Between 1942 and 1943 BMW, Focke-Wulf conducted experiments using Fw 190A-4 to improve engine power.
<snip>
C3 injection produced more power than MW50 injection, furthermore it didn't require any additional tankage and the center of gravity issues that would create. There was some minor damage found to the engines pistons from MW50 testing but this was over 30 hours of accumulated running.
It's just not right to claim that the BMW 801 was not suitable for water injection, C3 injection was just better and fewer issues eg adding extra tanks, plumbing, C of G adjustments.

The extra fuel tankage also an extra tank, plumbing, CoG adjustments - not sure what is the point? The article you've provided the link says flatly: "Schlechte Ergebnisse mit MW 50", ie. "Bad results with MW 50". The article mentions burned pistons in case MW was used. It also says that duration of the tests with MW 50 was only 4.43 flying hours: " Erprobt wurde diese Anlage mit der Fw 190, Werknummer 231, und dem SKZ SB + IK über einen Zeitraum von insgesamt 4,43 Flugstunden."

The result of this work meant that in 1944 the Luftwaffe introduced not one but two different boosting systems.
Simple boost pressure increases initially went to the Fw 190A8 series fighters, the approval being in Jan 1944 though it doesn't seem to be coming out of production till june 1944.
C3 injection went to the Fw 190F and G series bombers. C3 injection was more powerful and boosted the speed of the Fw 190G 45km/h when it was carrying 3 x SC250kg bombs. They were essentially uncatachable by soviet aircraft till the LaGG 5 came out.
The two system were also combined. This is still the BMW 801D2 we are referring to here, the engine having incorporated advances from the advanced BMW 801E and BMW 801F programs.

So the two boosting systems were combined??? Source, please. You do know that LaGG-5 entered combat in late 1942?
C3 injection was used only in low gear, ie. under 1 km of altitude (no ram). The 'Erhoehte Notleistung' was applicable both in second gear.

BMW 801D2 1.42 ata 2700rpm
power at sea level 1800 ps metric horse power
Power at 5.8km 1490 ps metric horse power

BMW 801D2 1.57 ata 2700rpm
power at sea level 2060 ps metric horse power
power at 5.9km 1695 ps metric horse power

Unfortunately, here the renown Dietmar Hermann makes some mistakes. 1st, he does not deduce the power requred for the fan. 2nd (a bgger mistake) he gives a higher FTH for the over-boost (used in 'Erhoehte Notleistung') than for 'normal' boost (used in 'Notleistung'). Going by this chart (link), we can easily see that FTH for over-boost at second gear (for 1.65 ata) is about 1.2 km lower than for 1.42 ata.

Allied intelligence completely missed detecting these boost systems for 8 months, the first note being March 1945.
BMW 801 D Leistungssteigerung
Using these systems all the A/F/G variants of the BMW engined Focke Wulf 190 increase climb rates by 27% at 8000m.
Speed of the Fw 190A-8 was 22km/h faster at sea level and 25km/h faster at altitude. When carrying bombs the speed increase was 45km/h.

The boosted A-8 have had no adverse effect on allied operations in 1944 in the ETO - 1st, the overboost affected the speed and RoC mostly under 6 km, and that is way too low to matter, 2nd, the heavy A-8 needed any help to push it above 650 km/h, even if that's at 6 km. We can wonder how much the LW intelligence needed time to recognize a wide use of 100, 130 and finally 150 PN fuel , along with water injection for P-47. Stuff for another thread?

For C3 injection, when released from 1km limit in Jan 1944.
Before
Fw 190 A-8 644 km/h at 6.3 km and 548 km/h Sea Level.
After
Fw 190 A-8 667 km/h at 6.3 km and 570 km/h Sea Level.
In Imperial
Before
Fw 190 A-8 399.5 mph at 21500 ft and 340 mph Sea Level.
After boost increase
Fw 190 A-8 414.0 mph at 21500 ft and 353 mph Sea Level, in fact you'll find tests showing a 360mph speed at sea level and 414 at altitude.

I'm not sure from where do you pull those figures for overboosted A-8. This chart (link) gives speed of 652 km/h at 5.5 km for the A-8 using 1.65 ata. This chart shows the same, plus it shows that both A-8 and A-9 don't have MW-50 aboard, but the rear tank instead.

It's worth looking at What the P-47 was doing at the time. <snip>

Same as above - comparison with 2 distinctively different aircraft.

The BMW 801TS is also a 2000ps engine but it does not need to use short term emergency boost to achieve that. I is well within its detonation limits without either water injection, c3 injection or rich mixtures. (boost on the D2 was limited to 3 x 10 minute bursts per mission with 10 minutes military power in between). Emergency boost is only added a few months latter and they use MW50 because C3 injection wastes fuel.

Wrong re. MW-50.

The Fw 190A9 without boost is 3mph slower than the A8 with boost at sea level due to its greater weight (due to the engine armoring going from 6mm to 10mm) it is however faster at 22500ft being able to do 414mph.

Nope - the A-9 was faster also at the SL, it's engine making 1.65 ata vs. A-8 making 1.58 ata. Per chart posted just above; grante, just a few km/h.

The 801TS does not have C3 injection. In fact it will receive the MW50 injection first tested in 1942 in Luftwaffe service in December/January 1944. I have had documents cited that this produced 2400hp, this 20% increase being made up of a combination of the higher charge pressure of 1.82 ata and the charge cooling/contracting effect of the MW50 but I am reluctant to accept more than 2200hp since I have not seen them.

The 801TS does not need C3 injection. It will happily do 2000 PS at SL (minus 70 PS for the fan) at 1.65 ata. With 1.82 overboost, that would be some 2200 PS (again, minus power for the fan).
BTW - you have had documents cited, mentoning 2400 PS, but you did not see the documents?

I do not accept your statement about German C3 fuel achieving 140 PN. If you can provide a citation I would be overjoyed. I have poured over the allied intelligence files at fischer-trospch.org and there is no evidence that C3 ever reached 140. C3 was continuously tested by the allies. C3 was 96/125 around 1943 and a little more, 97/130 somewhat later in the war. Either way this fuel was never available to the BMW801.

I'd start the thread about the C3 fuel asap.

 

[tomo pauk]

part 2:

The R-2800 was in some ways inferior to the BMW801. For one the poor speed of the P-47 at low altitude was due to its inferior installation. Kurt Tank didn't put a cooling fan and a tight streamline cowl on for aesthetic reasons.

The fact that low altitude speed of the P-47 with 2800hp was so mediocre points to the inferiority of P-47 aerodynamics since with only 2000hp Fw 190 could keep up with it. The Fw 190 itself was aerodynamically inferior to aircraft such as the P-51, Tempest V, Seafury etc with their laminar flow wings which could delay compressibility drag. Both the Fw 190 and the P-47D/M/N are out of date.

Oh dear. Comparing the huge P-47 with tiny Fw-190, in order to prove the Fw-190 have had a 'better' engine.

The Fw 190 could use cryogenic GM-1 (nitrous oxide) to match the P-47 engine at altitude and the 115L multipurpose tanks usefulness was improved by C of G changes made possible by the increased weight of the engine. It was a moot given that GM-1 was more likely to be used in the Me 109 and that The Fw 190D13 was promising the same kind of 390-400mph sea level speeds as the Mustang by using brute force of the Jumo 213EB while retaining high altitude ability, a speed likely well beyond the P-47 and its 2800hp R2800. GM-1 was inconvenient given the need to develop a cryogenic handling system, having said that it awkwardness is overstated because the oxygen used in the Fw 190 was also cryogenic. In reality it was too difficult to deploy given the breakdown of the Reich's manufacturing capacity.

?? Let's start lumping in the one-offs in this thread.

Either way the 2600hp 801F, whose development was complete was to enter production in early 1945. So the 801F bar a few months would have ended up producing 2600ps while the larger R-2800 produced 2800hp.
There never was a 3500hp C series R-2800 engine in an airframe, that only worked in a test rig force blown by an external supercharger.

The 801F is rated in the book 'Flugmotoren und Strahltriebwerke' as having 2400 PS power for TO, while 2600 PS was made on the test bench.

edit: this one slipped through:

Power at 5.8km , 2700 rpm = 1490hp (5.8km = 20000ft)

Make it 5.7 km, the altitude where 1440 PS was obtained (no ram). That would be 18700 ft; 20000 ft = ~6100 m.

 

[ohogain]

I'd like to switch topics slightly. I've read often that the French Hispano-Suiza engines were criticized for their lack of a two speed or two stage supercharger. Since France fell in mid-1940, is this criticism fair?

I only joined this forum yesterday as a result of a discussion I read that took place on this forum back in 2008 that I found while researching superchargers. To quote one of the comments from that thread:

Shortround6
I think people get confused as to what was low altitude and high altitude in the late 30s. in 1939 ANYTHING and EVERYTHING that did not have a turbo charger was "low altitude". There were NO workable 2 stage mechanical blowers in any country and the 2 speed single stage super charger was only 6-7 years old and the ONLY production engines with 2 speed superchargers were the British Armstrong Siddeley Tiger, Bristol Pegasus and Merlin X, The American Wright Cyclone (since 1937) and the P &W Twin Wasp (after the Cyclone), and the German inverted V-12s.

While behind the English and the Germans in the deployment of 2-speed superchargers, the French were beginning to use the Szydlowsky-Planiol supercharger on their 12Y-45 and had mounted a 3-speed compressor in 1938 on their 12Y-5.