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Supposedly the BMW P.8028 engine with a two-stage supercharger offered no significant increase in performance over the Fw190A with the standard two-speed BMW 801,
But, what kind of performance could have been expected from a Fw190 with the BMW 8028 engine with the two-stage supercharger providing 1550hp at higher altitude, say, 23,000 ft or 7,000m?
Where have you read that?I read that the reason the BMW P.8028 was not produced and used in the Fw190 was because it "failed to demonstrate a worthwhile increase in performance".
How that helps the fellow member asking the question in the 1st post here?Most fighting over the Eastern Front was under 15,000ft
Response #4 In any event not a primary source.Where have you read that?
Thank you.Response #4 In any event not a primary source.
Problem the Germans had with 2 stage superchargers was the fuel and cooling.
The Germans could not use the same level of boost without detonating. And this is not just the total level of boost but the amount of multiplication over the ambient air.
For some reason the Germans never used it like the Allies did.Fuel used on Fw 190s was as good as the current-best Allied hi-octane fuel.
The BMW P.8028 was supposed to use intercooler between the auxiliary stage and engine-stage compressors.
For some reason the Germans never used it like the Allies did.
They ran higher compression in the cylinders (except for the Jumo engines?) and they may not have run the engines as rich at full power.
How that helps the fellow member asking the question in the 1st post here?
It does not.It explains why the RLM didn't see any milage in an alternative engine to the one already delivering outstanding service.
'What if…' a meaningless question if there isn't a question to be answered.
The R-2800-8 in the F4U-1 was good for 54in for take-off and 52.5-53.0 military.
With water injection it was good for 57.5-59.5 depending on supercharger gear.
Pretty much the same engine in the P-61 used 53in in neutral or high gear and 54 in in low gear for military power.
They used 60in in all gears for WER.
P-47s used 52-53 in until they got water injection.
A lot of radials were cooling limited.
How about all the fighting against P-47 Thunderbolts at 30,000ft?Most fighting over the Eastern Front was under 15,000ft
Fuel and cooling are separate problems.Problem the Germans had with 2 stage superchargers was the fuel and cooling.
The Germans could not use the same level of boost without detonating. And this is not just the total level of boost but the amount of multiplication over the ambient air.
Say you want to use about 15lbs of boost, at sea level you need to compress the air 2.0 times (rounding off a small bit) but at 23,000ft you need to compress the air about 4.95 times. Yes, the 2nd stage comes in handy, but the highly compressed air will be much hotter than the sea level air after compression so we need an inter cooler. and we still won't get down to temps at sea level.
It is also going to require several hundred HP to power the 2 stage so we need to burn more fuel or accept the difference in power, better than not using the 2nd stage but not quite the gain hoped for?
Now granted the air is a bit colder but the air at 23,000ft is about 84% as dense as the air is 18,000ft so we need more air (more drag) just to cool the engine that is making the same amount of heat in the cylinders even though 100-200hp less is making it to the propeller. Assuming the pane is making the same speed at both altitudes.
Wright never made a high altitude R-2600 engine. The R-3350 had a lot of problems. P & W used both intercoolers and water injection (and 100/130 fuel) to get high performance from the R-2800 and then redid the entire engine (new cylinder fins and cylinder heads) to get the engines for the P-47M & N and the engines in the F4U-4.
Liquid cooled engines had an easier time but did have limitations.
The Germans had a lot to juggle trying to 2 stage supercharge the BMW radials. Maybe a better intercooler would have allowed more power, but a better intercooler might require more cooling air creating more drag? Maybe they need more cooling airflow for the engine itself ? maybe they need a crapload more water/alcohol. maybe they need two of those solutions at the same time.
German fuel allowed something like 1.6Atm (48"Hg, 9RAFpsi) boost pressure.
Problem the Germans had with 2 stage superchargers was the fuel and cooling.
The Germans could not use the same level of boost without detonating. And this is not just the total level of boost but the amount of multiplication over the ambient air.
Say you want to use about 15lbs of boost, at sea level you need to compress the air 2.0 times (rounding off a small bit) but at 23,000ft you need to compress the air about 4.95 times. Yes, the 2nd stage comes in handy, but the highly compressed air will be much hotter than the sea level air after compression so we need an inter cooler. and we still won't get down to temps at sea level.
It is also going to require several hundred HP to power the 2 stage so we need to burn more fuel or accept the difference in power, better than not using the 2nd stage but not quite the gain hoped for?
Now granted the air is a bit colder but the air at 23,000ft is about 84% as dense as the air is 18,000ft so we need more air (more drag) just to cool the engine that is making the same amount of heat in the cylinders even though 100-200hp less is making it to the propeller. Assuming the pane is making the same speed at both altitudes.
Wright never made a high altitude R-2600 engine. The R-3350 had a lot of problems. P & W used both intercoolers and water injection (and 100/130 fuel) to get high performance from the R-2800 and then redid the entire engine (new cylinder fins and cylinder heads) to get the engines for the P-47M & N and the engines in the F4U-4.
Liquid cooled engines had an easier time but did have limitations.
The Germans had a lot to juggle trying to 2 stage supercharge the BMW radials. Maybe a better intercooler would have allowed more power, but a better intercooler might require more cooling air creating more drag? Maybe they need more cooling airflow for the engine itself ? maybe they need a crapload more water/alcohol. maybe they need two of those solutions at the same time.
A two-stage supercharged Wright R-2600-10 rated at 1,700 hp for takeoff and 1,380 hp at 21,500 feet powered the Grumman XF6F-1 Hellcat prototype (all subsequent Hellcats employed the P&W R-2800).Wright never made a high altitude R-2600 engine.