Re: [Paddlewise] Energy, force and work

Nels,
As a former helicopter flight engineer, let me inject a bit here. The 
source energy that moves those air particles downward resulting in the 
helicopter hovering comes from the fuel that powers the engines that turns 
the driveshafts, that turns the rotor blades, that pushes those same air 
particles downward with the opposite effect of causing the helicopter to 
hover. Hovering, flying up, down, forward, backward or sideways makes 
absolutely no difference except in the "amount" of energy required to 
perform the desired maneuver.

If the fuel (the source of the energy) runs out, that baby is going down.
Dave G. <who remembers wondering if we were gonna stay in one piece when 
the torque indicators showed 110% (military) power with heavy load at hover 
in hot and high altitude conditions>

At 06:06 PM 12/12/2002 -0800, Niels Blaauw wrote:
>According to Matt it takes a constant supply of energy to keep a boat
>lifted. According to Peter is does not. Actually, they are both right.
>It depends on the circumstances. The main problem is their choice of
>examples: Airplains and musclepower are clearly too complicated to bring
>their views together.
>
>Let's consider a new example: A helicopter, flying, but not moving.
>According to Peter, the helicopter does not use energy to stay in its
>place. Correct! However, when the engine stops, the helicopter will fall
>like a brick. Why? Because the helicopter may not be using energy to
>stay in place, it DOES use energy to move air particles downward. The
>force used to accelerate these particles keeps the helicopter in place.
<snip a bunch>

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