A diesel engine developed in Germany and installed in Austrian airframes could change all our notions about designing piston-powered aircraft.
What is in this article?:
- Throw out the textbooks, diesel airplanes are here
- Dynamic Diesel performance
- The beauty of diesels and variable-pitch props
The beauty of diesels and variable-pitch props
Aircraft engines are more heavily loaded than auto engines, but they tend to run at constant speeds, which reduces wear. Automobile engines suffer immense wear by running at a wide variety of speeds as they constantly accelerate and decelerate.
The Centurion 1.7, for example, has only three power levels: takeoff, cruise, and idle. Thus, mechanical components, as well as engine management and prop operation, can be optimized for these three regimes. This lets airplanes get more usable power from their engines, which tend to be more durable than automotive engines.
Although rated at only 135 hp, the Centurion 1.7 can replace more powerful gasoline engines because it provides more static thrust. Static thrust is what you feel when you push the throttle forward. It is a function of engine torque, gear reduction to the propeller, and pitch of the blades. The Centurion static thrust, for example, is greater than that of a Lycoming O320 and equal to that of the more powerful Lycoming 0360.
With a fixed-pitch prop aircraft, takeoff rolls are much like trying to speed off in a stationary car that's in high gear. The variable pitch (i.e, constant-speed) prop of the Centurion provides somewhat of an aerodynamic "gear reduction" and is more efficient than fixed-pitch props used with Lycoming engines. This leads to the Centurion 1.7's better takeoff performance as compared to a PA-28 or Cessna 172.
Under so-called standard conditions, the Centurion's climb rate will be slightly less than that of the Cessna or Piper, but it still meets FAA standards. And with turbocharging, the Centurion can be expected to perform well in hot weather and from high-altitude airports, both of which degrade engine performance.