P
Polux
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Every day is looking much better!!
You have nearly finished
You have nearly finished
Not yet Polux, not yet ...\ said:Every day is looking much better!! You have nearly finished
\ said:Looks great Francesco.Increasing the number of blades on a propeller is one way of improving power absorption through propeller solidity (the solidity of the spinning disc). When you consider that the Griffon 65 as seen in the Spitfire Mk.XIX could put out almost 2,000HP, that is nearly twice what the early war Merlins could produce. That is why you see an increase in blades as the type developed with more powerful engines. Later, contra-rotating propellers did the same thing, but also reduced torque effects as they turned in opposite directions. An interesting fact is that many pilots struggled to control the later aircraft on take off due to the massive torque produced from these enormous engines. More than one experienced Spitfire pilot came to grief because the Griffon actually turned the propeller the opposite direction to the Merlin (anti-clockwise as viewed by the pilot). Wrong pedal and full power = significant loss of ground control.
I came across the principle of reverse torque (could that be the correct technical name?) last year in single-engined planes. On a rapid opening of the throttle while taking off, the whole plane (fuselage) could roll violently. This presumably is due to the sudden high torque applied by the engine to the spinner. Because of Newton's third law "When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction on the first body", the spinner exerts a huge torque on the fuselage in the opposite direction. The pilot must counter this quickly.\ said:Looks great Francesco.Increasing the number of blades on a propeller is one way of improving power absorption through propeller solidity (the solidity of the spinning disc). When you consider that the Griffon 65 as seen in the Spitfire Mk.XIX could put out almost 2,000HP, that is nearly twice what the early war Merlins could produce. That is why you see an increase in blades as the type developed with more powerful engines. Later, contra-rotating propellers did the same thing, but also reduced torque effects as they turned in opposite directions. An interesting fact is that many pilots struggled to control the later aircraft on take off due to the massive torque produced from these enormous engines. More than one experienced Spitfire pilot came to grief because the Griffon actually turned the propeller the opposite direction to the Merlin (anti-clockwise as viewed by the pilot). Wrong pedal and full power = significant loss of ground control.
Hi Steve.\ said:I came across the principle of reverse torque (could that be the correct technical name?) last year in single-engined planes. On a rapid opening of the throttle while taking off, the whole plane (fuselage) could roll violently. This presumably is due to the sudden high torque applied by the engine to the spinner. Because of Newton's third law "When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction on the first body", the spinner exerts a huge torque on the fuselage in the opposite direction. The pilot must counter this quickly.But during normal especially high constant speed flight at full throttle, why doesn't the fuselage permanently spin (roll) in the opposite direction to the spinner? Could the answer be that the pilot has to keep the ailerons always adjusted in a position to counteract that roll? If so, the added air drag must slow the plane down considerably.
Added:
Also, I would think that despite counter-rotating props, the torque applied by the engine to the spinner (and the reverse reaction torque by the spinner) would still be there unchanged.
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