Originally Posted By: Drew99GT
Originally Posted By: Pelican
Amazing Draco, but are all those HP really necessary? Fuel consumption must be enormous, a real killer for a bush-plane.
He says in the vid that because he can fly like 50 knots faster and higher altitude, he actually gets better fuel mileage with the turboprop.
Hahahahaha, I find it exceptionally hard to believe that a turboprop will use less fuel block to block, or even exhibit any real efficiency. There is a reason the piston engine persists. And it's not cost. It's fuel economy. Thrust, and therefore speed, takes HP. And HP takes fuel.
https://en.wikipedia.org/wiki/Brake_specific_fuel_consumption
3/4 the way down the page is a great chart of turboprop efficiency
Bottom line 6.6% efficient at idle, 16.8% on approach and 27% in cruise, 29% at takeoff.
The best piston engines available today are pushing 40% efficient. The 1960's Lycoming's are at least 35% efficient.
Yes, turbines can be reasonably efficient in takeoff and cruise, and the larger the more efficient. But they suffer in all other modes, including ground operations, where lots of fuel is consumed, doing no work at all, idle is 50% after all.
In our turboprop, it's not unusual to see 30 gallons per hour on the ground, 100 gallons per hour on takeoff and 60 gallons per hour in cruise flight.
Contrast that with piston engines that use near nil on the ground and near nil in descent and are more efficient in cruise.