Caterpillar/Wright 1820 into a diesel, could it be used in aircraft such as B17?

[gumbyk]

You don't really need huge amounts of torque for an aircraft engine (especially a bomber where most of your time is spent at cruise power settings, and there aren't throttle changes being made). Gas turbine engines don't have a lot of torque (comparatively speaking) but put out plenty of horsepower.

 

[wuzak]

You don't really need huge amounts of torque for an aircraft engine (especially a bomber where most of your time is spent at cruise power settings, and there aren't throttle changes being made). Gas turbine engines don't have a lot of torque (comparatively speaking) but put out plenty of horsepower.

No, but they run at higher speeds, so that the engine output has to go through a reduction gearbox to the prop.

If you have x hp at y propellor rpm then the torque is the same at the prop regardless of what is happening in the engine.

 

[pinsog]

You don't really need huge amounts of torque for an aircraft engine (especially a bomber where most of your time is spent at cruise power settings, and there aren't throttle changes being made). Gas turbine engines don't have a lot of torque (comparatively speaking) but put out plenty of horsepower.

Horsepower in merely a mathmatical equation that shows what torque can do over time. hp=torque x rpm/5252

 

[rinkol]

Two points:

1. In comparison with gasoline engines, diesels run very lean (i.e., the combusion process does not consume all of the available oxygen). Consequently, for all other factors being equal, you will get less power.

2. The higher compression ratio increases stresses and requires components to be strengthened, otherwise reliability will suffer - back in the late 1970s, efforts to convert gasoline auto engines to diesel operation mostly turned out badly.

For a while in the early 1930s, it looked like diesel engines could be competitive. However, the development of high octane fuels, coupled with improvements in supercharging and cooling enabled gasoline engines to provide greatly increased power, at least on a short term basis. This turned out to be important for modern high performance aircraft. These tend to have relatively high wing loadings and rely on a combination of high power levels at takeoff in combination with flaps and other high lift devices to keep take-off distances manageable. Note that the high lift devices increase drag even more than they increase lift, so takeoff power is critical.