Two stagers

[tomo pauk]

In order not to clog the current 'ideal P-47' thread, maybe it would be okay to start a new thread that would cover the most interesting Anglo-American engines and their applications, namely Merlin and R-2800. It can be argued that turbo R-2800 was a two-stage engine, since the turbocharger was also a stage in compressor system.
For starters, here is the table with R-2800-10, the engine used in Hellcat, along with Merlin Mustang's engines. The R-2800-8 was used in Corsair, and was basically the same engine. Some sheets, eg. the one found at William's site, list the military power of the -8 and -10 engines as being 1650 HP at 21000 ft. Any information that might clear the 1500 ft discrepancy is welcomed. The 1800 HP at 18500 ft is a war emergency power value (max WER was at 1950-2000 HP at a bit lower altitude), not military power. Power values are without ram.
Please open the pic separately for high resolution.

 

[Shortround6]

This chart or series of charts while a good resource is rather subject to misprints or copying errors. It is certainly a good start but I would rather not rely on it in the face of other sources (or sometimes just common sense) as sometimes altitudes are off by 10,000ft ( a 2 instead of 1 typed in the wrong spot) too many ditto marks in columns for engines that were not the same or sometimes engine powers copied from one line to another.

 

[tomo pauk]

You are probably right. Even the most celebrated sources can get sometimes wrong. Here is a few tables for the 2-stage R-2800 I have, they don't quite agree about the full throttle altitudes. Please note the feeble gain in conditions of with ram vs. no ram for the -10: only 2000 ft at circa 400+ mph.
BTW, were there any differences between the -8 and -10 worth talking about?

 

[Shortround6]

With the first chart the speed for the "RAM" is not given. You get some RAM even at climbing speeds , just not much, RAM also depends on the intake ducts/system.

See the flight test results for "true" full throttle altitudes.

 

[tomo pauk]

Looking at the aircraft data sheets at Williams' site, the difference between rammed and 'static' full throttle altitudes is circa 2500 ft, no matter whether the military power was used or WEP. Unfortunately, the RAF data sheets give circa 15 mph lower speed than some US data - difference whether rack(s) were installed or not? Test do give circa 22000-23000 ft FTH for mil power and 20000 ft for WER.
Think we can safely assume that table's FTH values with ram are at max speed at setting applied - both for 23000 ft (mil power) and for 20000 ft (WEP).