Recent content by rinkol

One thing that struck me was that both Issotta-Fraschini and Piaggio licensed the Gnome Rhone K-14, an engine with limited development potential, partly due to the lack of a center bearing. The former produced very few of these engines and might have done better by licensing the DB engines or...

The Jumo 213e/f had a two stage supercharger with three speeds. I believe theer was also a late model RR Griffon that was similar in this respect.

The practical reality was that the BMW 801 was the most powerful engine suitable for service use from 1941-1944. Both DB and Junkers had serious problems into 1944. The radial engined FW 190 ws also a preferable choice for ground attack than the versions with liquid cooled engines.

The GR-14M wasn't exactly renowned for reliability. There is also the issue of TBO. Some of the wartime engines were extremely maintenance hungry.

I think the muzzle velocity is something that is an issue and makes a difference. If you have a high muzzle velocity, then you can rely on the kinetic energy to result in significant effect at the target. Conversely, with a lower muzzle velocity, it becomes more worthwhile to use explosive...

I suspect a folding wing Spitfire would present problematic structural issues in view of the thinness of the wing.

They were preoccupied with the V-1710. I have some doubts about the V-3420. If it was considered mature at an early stage, the replacement of the problematic R-3350s used in the B-29 would have been a no-brainer.

There is the further issue that elliptical wings have complex 3D curves that would make it very difficult to achieve a sufficiently accurate profile needed to make an effective laminar flow wing.

I recall seeing one of these at a museum in Alberta.

"German fighters were using 87 octane fuel but US, UK using 100/150 octane fuel when they are testing captured Bf109." Not sure this would have made much difference unless the engine were adjusted to use higher boost levels.

Wasn't reliable during the war.

You need ducting for air and exhaust gases and an intercooler in addition to the compressor/turbine combo. You either end up with a cockpit near the tail (XP-37) or run the ducting past the cockpit (Fw 190C and XP-60A). The latter spoils the advantage of the in-line engine in minimizing frontal...

I would add that, for high performance aircraft, one would likely do better going with a clean sheet of paper design using jet engines. With jet engines, one could normally use a shorter undercarriage and it was worth making design choices for operation at high subsonic speeds.

A short crankshaft, all things being equal, will have a much higher resonant frequency for torsional vibrations and generally shouldn't twist as much, as would happen with a long crankshaft. The amount of twisting over the length of the crankshaft can be a significant issue for valve timing...

It seems they would have been better off focusing on their liquid cooled engines. There was a somewhat similar issue in Italy with Isotta-Fraschini licensing the GR 14K - they didn't seem to have much success either.