Quote:
Originally Posted by basjoos
Even though the Cub's nose is pointed up at 45 degrees, the wing's 10 to 20 degree angle of attack means the aircraft's flightpath isn't anywhere near a 45 degree angle.
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You are right about the old J3C Cub, but there are plenty of aircraft that can make a 45 degree angle of climb.
Quote:
Originally Posted by basjoos
But propulsion via ground friction allows you to use a "granny gear" to climb up a steep road on very low horsepower. According to my owner's manual, 1st gear allows the 54hp engine in a 67 VW Beetle to propel the 1900 lbs car up a 45% incline (VW beetles are known for their extremely high 1st gears that redline at about 12mph). Show me a 54hp, 1900lbs airplane that can climb out with a flightpath anywhere near that angle.
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Again, if the propeller makes enough thrust you go up.
45% grade is 24.2 degrees - about what that Cub (by the way, last built in 1947) is doing with 65 hp. In any case I don't plan to fly up a steep driveway, but a pusher prop would do the job just as well as a "granny gear"
But what the OP suggests is really having a small engine and pusher prop to provide thrust during those cruise conditions where the SUV's engine is way over sized. Assuming use only during cruise conditions, the prop is 85% efficient and the small engine can be designed for 33% efficiency at that power (combined about 28% efficient) compared to the SUV engine at 22% efficiency and drive train about 95% efficient (combined 21% efficient). A tire - prop hybrid could makes sense - in a unicorny way.
-mort