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OP:
Torque is a measurement of power from the engine, at the gear box of the prop/rotor. The reason for torque indication is the gear box has limitations on how much power it can handle, as it's being resisted on the other side by the prop/rotor, which is being resisted by the drag from the air. Certainly you can measure torque of the engine, torque to the prop, but usually the gear box is the weakest link, as it's translating the power from the engine to the airfoil...so it usually gets the indicator, with your job keeping it out of the red. |
Keith:
As the collective is lowered the aircraft starts to descend and the induced velocity and the induced power both fall to zero. As the aircraft accelerates downwards the direction of the total reaction is tilted in the direction of rotation at some points along the blades and is tilted in the opposite direction at other points. It is only when a certain rate of descent has been achieved that the sum total of the different parts of the total reaction is sufficient to keep the blades rotating in the correct direction and to produce sufficient lift to support the weight of the aircraft. When the sum of lift plus vertical component of drag equals the weight of the aircarft the ROD becomes constant. The actual rate of descent depends upon a number of things include blade pitch angle and aircraft weight. I have known several hundred helicopter pilots over the years, but none of them have flown theoretical discs. They have all flown real helicopters with real rotor mechanisms. You are using the behaviour of real systems to support arguments about theoretical physics, then you are saying that the actual mechanical arrangement of the systems is superfluous. That line of argument is clearly nonsensical because the behaviour of the real systems is determined as much by their physical characteristics as it is by the theoretical physics When an aeroplane is standing still on the ground with wheel brakes applied the THP is equal to Thrust x propwash velocity. |
I thought you might wish to deny one or more of your errors, so I did a search.
1. Propellers continue produce THP when the aircraft velocity is zero. Page 1 post 8 “Not that myth again. It's disappointing to have to point out to one who calls himself an instructor that in your 'brakes on' scenario the aircraft is still producing 200 THP as well as 200 BHP because it is accelerating a mass of air rearwards in a futile attempt to turn the earth and the atmosphere in opposite directions.” 2. When an aeroplane is standing still on the ground with wheel brakes applied the THP is equal to Thrust x propwash velocity. Page 1 post 14 “But that does not mean a stationary aircraft can do no work and therefore produce no THP!!! The work is done by moving the mass of air one way and the mass of the Earth a tiny imperceptible amount the other way. “ 3. If propellers produced no THP when the aeroplane is standing still on the ground, it will be impossible for the aeroplane to accelerate when the brakes are released. Page 6 post 120 “Sure, no power is required if the aircraft is at standstill but that does not mean no power is available. OTOH power is required to accelerate the mass of the vehicle from standstill with or without aerodynamic drag. No power available = no acceleration. THP is the power available. If the aircraft has to move before you get THP then you are in a chicken and egg situation - you can't accelerate the aircraft without power but you can't have power until you move the aircraft.” 4. If THP is Thrust x TAS it will be impossible for aircraft to accelerate in flight. Page 7 post 148 “Aircraft flying straight and level at speed Va, pilot sets new power to accelerate to Vb. Assume constant propeller efficiency between Va and Vb due variable prop. Final THP = thrust x Vb, we agree that much. Using the hypothesis you outlined above we can draw some conclusions: The new power is set, the BHP has gone to the prop but THP doesn’t catch up until the plane reaches Vb?! Thrust horsepower during the acceleration is less than final THP when you get to Vb?! Thrust must have increased, but this didn’t reflect an increase in THP, this was because power was wasted in the propwash?!” If you look at item number 2 above you will see that Page 1 post 14 “But that does not mean a stationary aircraft can do no work and therefore produce no THP!!! The work is done by moving the mass of air one way and the mass of the Earth a tiny imperceptible amount the other way. “ implies that When an aeroplane is standing still on the ground with wheel brakes applied the THP is equal to Thrust x propwash velocity. It really is time for you to face up to the fact that virtually everything that you have written in this thread has been nonsense. |
Keith Williams:
If you look at item number 2 above you will see that: Page 1 post 14 “But that does not mean a stationary aircraft can do no work and therefore produce no THP!!! The work is done by moving the mass of air one way and the mass of the Earth a tiny imperceptible amount the other way. “ implies that When an aeroplane is standing still on the ground with wheel brakes applied the THP is equal to Thrust x propwash velocity. It's pretty well known that at the propeller, the air has accelerated one half of what it will do downstream (VI = 1/2 ΔV). So, at the propeller, the velocity is VA + 1/2 ΔV. |
If you feel the need to hang on to that figleaf ogger then do so.
Life's too short for me to waste any more time conversing with you oggers. I'm sure most of the people who have followed this thread have come to the same conclusion. |
Keith that's the second time you've scurried off. However, since your last reappearance you have spouted plenty of waffle in my direction [including explicitly "inviting" me to comment]. So whether you care to read it or not I will be commenting further on the many spurious points you addressed to me :ok:
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