A place for some discussion about how FS models piston aircraft engines. With FSX some degree of modeling of supercharged planes is apparently possible. I haven't seen anyone put together a good working model as yet that mimics how the WWII era aircraft with multistage blowers using this system without extensive gauge work.
FS does a pretty god job of modeling a turbocharged engine with automatic controls. to set this up about all is necessary is to get the sl HP and mp correct and set the critical altitude in the CFG. File. The HP delivered as altitude increases is pretty constant as altitude increases up to the critical altitude. For the real world aircraft the max boost available was determined by such things as turbine speeds and temperatures.
For the supercharged engine, typically there was a basic supercharger stage and an auxiliary blower that could have several gearing speeds to provide additional boost as Tyne aircraft climbed. FS does not model this well. At sl the engines were run with just the primary blower, perhaps up to 5000 ft or so, at which it was advantageous to shift into low blower, which could maintain rated MP up to some altitude, say 12,000 ft for discussion. Above that high blower could keep the max MP to some altitude in the low-mid twenties. The aux stages used power from the engine, soot was best to not shift to a higher and more power robbing stage till necessary.
The supercharged engine produces a power vrs altitude curve which is a zig zag. So far the best compromise for supercharged engines has to been to assign them a turbocharged status and get a best fit for the points of the zig zag, at least anchoring e power/speed points at sl and critical altitudes. This does generally give reasonably accurate speeds for the aircraft. Some have gone with the idea of simply starting out with a huge possible MP value at sl which will diminish to rated HP at critical altitude. This depends on the user to manage the Mp to a reasonable value at lower altitudes. However the engines did not work like this, some FS planes have developed 4-5,000 HP out of a 2000hp engine at sl using this system. It is not how the engines worked.
If someone has figured out how to make the FS system work it is a good place to start the discussion.
T
Bookmarks