Fri Jan 23, 2015 10:56 am
#1346604
As all you power-pilots know, you run up your engine to full power, yet poxy little glorified go-cart brakes can hold your aircraft stationary...Why, even a push-bike is better braked.
Now, Haven't you ever asked yourself just how these pathetic retarders can hold back an engine capable of propelling the whole caboodle at~100MPH ?
The answer , is the coupling of the propulsion-system to the surrounding air-mass.
ISTR some talk (perhaps it's reality?) of airliners having motorised Gear wheels to allow taxiing without all that expensive and inefficient air-stirring from the Donks which are only efficient with a greater differential between airspeed of engine anhd ambient.
You release your brakes and as the prop/jetblast get a more effective "grip2 on the ambient air, power-transfer becomes more efficient....the process is exponential...the faster you go, the faster you accelerate (until drag becomes a major issue.....
So, why not use a lightweight motorised wheel to save that initial huge gollop of fuel needed to taxi and get to a speed where a conventional engine is starting to get a bit efficient (coincidentally, I see Lift/drag rising to the point where the wheels' traction becomes marginal at about the same speed, so a symbiotic relationship )
I seem to recall a certain Scandinavian Airline pilot who was quite happy to bung a couple of model jet-turbines on his boots and cross the channel in his wing-suit.
My only reservation is the fuel-consumption V thrust usable....I have a gut feeling that a sailplane is not going to make better use of a pound of fuel, as will a propellor.