Quote:
Originally Posted by RedDevil
It is frustrating to see how you miss it. I really did not expect that.
You're so convinced it cannot work that you can't bring yourself to studying it in detail.
If you set the blades of the propeller flat, so the wheels make it spin but it does not push the air forward or backward compared to the car, do you agree that the wind will push the car forward, albeit not as fast as the wind?
Now if you alter the angle of the blades so that it pushes slightly against the wind, do you agree that would only increase the pressure on the blades leading to an even greater forward force, although a part of that is needed to overcome the resistance of moving the blades against the wind?
A sailboat cannot sail straight against the wind because its mast does not move relative to the boat. But propeller blades do move and that has the same effect as a sail boat tacking back and forth to end up in a position that is straight against the wind from the starting point.
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1) In # 37 ( permalink ), some other dave states that it is the 'triangular
sails- propeller blades' that are responsible for Blackbird's motion.
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2) The wheels cannot power the propeller if the propeller is the sole source of power for the wheels.
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3) If you examine turbine blades and propeller blades, you may find that their airfoil geometries are 'reversed.'
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4) In a bonafide powerplant failure during flight, in a variable-pitch propeller aircraft, the aircraft checklist instructs the pilot to 'de-pitch' the prop, in order
to reduce prop-drag, thereby increasing glide radius for a dead-stick landing.
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5) The 'Blackbird' propeller analogy implies that, in a flight emergency, the pilot would merely 'reverse' the propeller ( like a Lockheed C-130 Hercules ), and the free-wheeling reversed propeller would now be capable of maintaining enough thrust for level flight.
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6) The 'masts' which hold the aircraft propeller are free to move in relation to the aircraft fuselage.