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In the US the oil was not "as good," and the oil industry had to invest heavily in various expensive boosting systems. This turned out to have benefits: the US industry started delivering fuels of increasing octane ratings by adding more of the boosting agents, and the infrastructure was in place for a post-war octane-agents additive industry. Good crude oil was no longer a factor during wartime, and by war's end, American aviation fuel was commonly 130 to 150 octane. This high octane could easily be used in existing engines to deliver much more power by increasing the pressure delivered by the superchargers. The Germans, relying entirely on "good" gasoline, had no such industry, and instead had to rely on ever-larger engines to deliver more power.
However, German aviation engines were of the direct-fuel-injection type, and could use methanol-water injection and nitrous oxide injection, which gave 50% more engine power for five minutes of dogfight. This could be done only five times or after 40 hours run-time, and then the engine would have to be rebuilt.
Most German aero engines used 87 octane fuel (called B4), while some high-powered engines used 100 octane (C2/C3) fuel.
This takes honours. Even the German aces have said this. There exists an argument it is a retospective benefit rather than design goals. But the original design was the BF-108 with an inverted V-8. I'd say definitely the design goals of that layout then was pilot view and low CG (as a civilian sports and military liason type), and probably ease of maintenance under field conditions.The Inverted V-engine, gives the airframe a larger angle to the usually low mounted wing. This reduced interferense drag and this was also the reason why the pilot head space was rather small. Nevertheless it was one reason why the 109 had a surpisingly high diving speed, what saved also their lives quite often.
My best guess is this created an engine with a lower center of gravity, putting most of the weight at the "bottom" of the engine instead of the top. It also made servicing the engine somewhat easier, as most of the "complicated" stuff (fuel lines, spark plugs, ignition wires, valve covers, etc.) was at the bottom of the engine, not the top, where it would be easier to get to.
The bad news is this required a "dry sump" lubricatiing system, which is more complicated than a "wet sump" lubricating system.
One further reason: the gyroscope effect. Remember that most of the a/c with propellers uses this advantage in maneuver. The increased weight of rotational parts, in the attempt to obtain bigger engines, read more HP, deemed designers to put the crank as close as possible to longitudinal center line, in the attempt to reduce negative gyroscope effects, and increase maneuvering capability.
Of course, if the engine is too big, the heads would be in front of pilot's sight. In order to maintain pilots view, and the body as narrow as possible, the germans decided to invert the engine and put the pilot behind it. The americans invested on new wing's profile to reduce drag. Check out how much higher is the P-51 fuselage compared to the ME 109.
The problem with the 109's landing gear wasn't the hight: it was just too narrow. Germans made this way because the wings spar were too light, and would not hold the landing loads. Further more, the hydraulics were simple too.
Best Regads
Beto Aero
I didn't mention earlier. I've been told the inverted V gives better visibility over the nose from the pilots perspective.
I know some of the late Spanish built 109's had merlins in them. Was the Merlin converted to run in an upside-down configuration in this setup? anyone with Pics or knowledge of how this was accomplished?
KB
Didn't the prototype 109 fly with a RR Kestrel which must have been fitted uninverted. So the engineers would have had to redesign the engine installation for the RR 109s and the DB 109s. No easy fit.
I have read nothing saying the original 109 was ever intended for night fighters so not sure about the exhaust configuration.