1265 miles with a 90 imp gal drop tank: link
I didn not see any range figures for the 170 gal drop tank.
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Maybe you can answer a question for me on this - I had read that the Spit VIII etc. was a "long range" version of the Spit, but in googling it recently i saw range figures of ~650 miles which sounds like 'medium' range at best. A little less than most US fighters except the Wildcat. Is that the right number? What is the actual range of the Spit VIII?
S
Maybe you can answer a question for me on this - I had read that the Spit VIII etc. was a "long range" version of the Spit, but in googling it recently i saw range figures of ~650 miles which sounds like 'medium' range at best. A little less than most US fighters except the Wildcat. Is that the right number? What is the actual range of the Spit VIII?
Not that fast, the P-40 with 1700 HP, since that power was availabe at low level where the air is thick = plenty of air resistance. Though the climb would've been excellent.
Any military matter, no matter how well spread, will be deemed as secret in official docs in a time of war.
As for the over-boosting their respective engines, one needs hi-oct fuel to help out. Allies were in better position there, Axis forces not so much. So we can see many late-war German and Japanese engines outfitted with ADI systems instead, so over-boost can be achieved, and with it the engine power. The BMW 801D and S, as well as Jumo 213 were taking advantage of ever-higher rich rating of the German hi-octane C3 fuel in later part of the war.
Granted, people can use the hi-oct fuel and ADI in the same time for the best result.
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Speed increase would be limited but not negligible, probably at least ~20 mph or so. Climb rate would almost double temporarily and acceleration would jump up too. With takeoff rated settings a fully loaded p-40K has a hp/lb ratio of a fairly sedate 0.16. But at say, 1,600 hp its a more respectable 0.19 and at 1,700 hp it's at 0.20. If you assume they used ~500 lbs of fuel by the time they got engaged, change that to .20 for 1,600 and .21. Roughly equivalent to a Spit VB. This would make a P-40 much more dangerous at low altitudes for the LW.
If they were using 60" at a standard power setting then presumably that means for 15 minutes.
I think this should be mentioned on the P-40 Wikipedia page.
Very interesting. So Allied engines could really boost way over the takeoff power rating (assuming the good fuel is available) but German fighters not necessarily so.
S
No, anything over 42-45in on an Allison was WEP power
see. http://zenoswarbirdvideos.com/Images/P-39/P39SEFC.pdf
For limits on a P-39Q.
ANY use of WEP called for a notation in the log book. Now as time went on it may have taken more notations or notations of longer periods of use before the engineering officer decided to change the plugs or check for metal particles in the oil or take 10-20 hours off the life of the engine before pulling for overhaul.
This is also subject to operational requirements and the availability of spare spark plugs and spare engines. Engineering officer is using his best judgement to balance extra wear and tear on the engines with need to keep planes in the air with his manpower (mechanics) and spare parts.
Pilots did not use anything over military power no matter how briefly and NOT tell crew chief/engineering officer.
and again, if you had an engine with 9.60 supercharger gears, 66in was forbidden, ever, upon penalty of holing a piston or putting a rod through the side of the block. Maybe the Russians did it but a forced landing on Russian soil was a lot different than a forced landing in the Pacific Ocean.
From what I read, when they landed the crew chiefs could immediately tell if they had been 'pushing the engine' because you would usually see scorch marks and oil coming out of them.
Certainly the case in WW2 Hawker Tempests with a similar arrangement for breaking wiresI don't know about the entire war but for period the crew chief could tell by looking at the throttle in the cockpit. Before takeoff there was a thin wire fastened across the throttle gate with a seal. If the plane came back with the wire intact then the pilot hadn't used the the WEP, if it came back broken or missing then he had.
any chance of some evidence for these assertions?It is interesting that WW2 planes engines did not have oil or air filters.
So contaminates also were a cause for early wearing out of the engines.
Peace time operations also ran engines at lower HP levels!
Combat pushed the engines to their limits as it was a life death situation.
Maximum performance and how to get it became a game.
Germans standardized on 96 octane fuel and used ADI or NOS to improve performance.
Allies had 100, 130, and 150 octane, Radial engines adding ADI for more performance.
German engines were 37 liters to our 28 liters and rarely ran them above 2800 rpm.
The Allison was pushed to 3600 rpm, mostly limited to 3200 and the Merlin 3000.
Some of the later British Sleave Valve engines went to 4000 rpm
To get more power the Germans would bore out their engines and port and polish the runners.
Always wondered what a Reno Racer air speed would be at best altitude?
When comparing engines you have to look at a lot of things.
And once a country starts on a few engine designs they tend to get stuck with them, you cannot retool factories on a whim.
The DB 601 and Jumo 211 were much larger displacement engines than the Merlin and Allison. But the aircraft designers don't give a hoot about displacement.
This isn't auto racing, Planes are not divided up into classes depending on the displacement of their engines.
The Merlin III, the Allison C-15, The early DB 601s and the early Jumo 211s weighed within about 100lbs of each other, they were within a few inches in width and in hight and they made similar power at similar altitudes. Merlin bit ahead.
The Germans had traded displacement for RPM. Since everybody started with 87 octane fuel (mid 30s) nobody could use much more boost than anybody else.
Germans went with a large displacement but lightly stressed engine (low rpm) rather than a high rpm engine.
And BTW, Rpm can very misleading, it depends on what you are trying to compare. For comparing pistons, rods, crankshafts and bearings a much more useful figure in piston speed. An even better figure is the corrected piston speed which is the mean speed divided by the square root of the stroke to bore ratio.
This gives a much better indicator of the bearing loads.
And please note that bearing loads, like many other things (like friction) go up with the square of the speed.
I would also note that once you get to high powered aircraft engines everybody was polishing the ports/runners. Nobody was going to leave rough cast surfaces and then have to put more HP into a supercharger to get the desired airflow.
Once the Germans (or the British) were tooled up to make certain engines they had to stick with what could be made on prtty much the same tooling machinery.
I read recently that Rolls Royce considered the limit for internal combustion engines was 6" bore and stroke. Above that
I don't know about the entire war but for period the crew chief could tell by looking at the throttle in the cockpit. Before takeoff there was a thin wire fastened across the throttle gate with a seal. If the plane came back with the wire intact then the pilot hadn't used the the WEP, if it came back broken or missing then he had.
Yes go readany chance of some evidence for these assertions?
Yes go read