How turboprop engine power is rated?
The most basic measure of power — and the one listed in the airplane specifications — is the maximum shaft horsepower (shp) of the engine. So the maximum amount of power — thrust, actually — that a turboprop engine is approved to produce at any time on a specific airplane is stated in shp and is a certified limitation.
How much horsepower does a turboprop have?
Another measure of power in a turboprop is Thermodynamic Horsepower. This a calculated number based on the known amount of energy “contained” in the fuel that can be released by burning that fuel. When this calculation is done on our PT6A-135A the number is a maximum of around 920 HP.
What is SHP in engine?
Shaft horsepower (shp) is the power delivered to a propeller shaft, a turbine shaft, or to an output shaft of an automotive transmission. Shaft horsepower is a common rating for turboshaft and turboprop engines, industrial turbines, and some marine applications.
Do turboprops use jet fuel?
The two kinds of fuel most commonly used in General Aviation are Jet fuel and Avgas. Many modern turboprop planes also run on Jet fuel, as they feature engines with a gas turbine which power their propellers.
Why Are turboprops more efficient at lower altitudes?
Compared to turbofans, turboprops are most efficient at flight speeds below 725 km/h (450 mph; 390 knots) because the jet velocity of the propeller (and exhaust) is relatively low. Modern turboprop airliners operate at nearly the same speed as small regional jet airliners but burn two-thirds of the fuel per passenger.
Why do turboprops use constant-speed propellers?
To maintain propeller efficiency across a wide range of airspeeds, turboprops use constant-speed (variable-pitch) propellers. The blades of a constant-speed propeller increase pitch as aircraft speed increases. Another benefit of this type of propeller is that it can also be used to generate reverse thrust to reduce stopping distance on the runway.
How is the power output of a turboprop engine measured?
The power output of a piston engine is measured in horsepower and is determined primarily by rpm and manifold pressure. The power of a turboprop engine, however, is measured in shaft horsepower (shp). Shaft horsepower is determined by the rpm and the torque (twisting moment) applied to the propeller shaft.
How fuel efficient are turboprop engines?
Turboprop engines are most efficient at speeds between 250 and 400 mph and altitudes between 18,000 and 30,000 feet. They also perform well at the slow speeds required for takeoff and landing and are fuel efficient. The minimum specific fuel consumption of the turboprop engine is normally available in
What is the maximum speed of a prop fan engine?
Propellers lose efficiency as aircraft speed increases, so turboprops are normally not used on high-speed aircraft above Mach 0.6-0.7. However, propfan engines, which are very similar to turboprop engines, can cruise at flight speeds approaching Mach 0.75.