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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:
NA had some vague ideas but were trying to survive against official obstruction from the USAAF (it's only customer really was the British).
"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. ".
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.
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.
Just to clarify, you mean NA's only customer for the P-51?
In contrast to, say, the B-25.
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.
Thank god for Roll Royce then. It was powerful enough and tough enough (under the great Hives) to ignore that nonsense from idiots.
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.
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....
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, 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.
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).
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.
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.
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
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.
<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 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.
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.
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. <snip>
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 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.
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.
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.
Power at 5.8km , 2700 rpm = 1490hp (5.8km = 20000ft)