rudderrudderrat:
I'm feeling an acceleration whist standing on the earth (force on my feet) and I'm perfectly balanced.
You are perfectly balanced and that means that there is no net acceleration. Imagine the earth to be stopped (not rotating). It would still have this gravity force as it's related to mass. To really give you a good answer you need to take some general relativity courses. General relativity deals with the theory of gravitation. I will try to explain a little bit about what's going on below.
We're analyzing these problems with reference to the earth and not a point in space so when you're standing on the earth, you are stationary. If we did analyzing the earth as 'it truely is', we would have to triple to quadruple the amount of work so that we compensate for the earth's rotating reference frame.
So, standing on the earth we consider that to be an inertial reference frame. When you are accelerating you're in a non-inertial reference frame.
Inertial frame of reference - Wikipedia, the free encyclopedia
What you feel when turning in the airplane is the centrifugal force which is a pseudo force. It is only there because YOU are in an accelerating reference frame. You don't actually feel the net increase in the lift force. If you were standing on the earth and saw a plane overhead in a turn, based on where it was going you would have to conclude that there is a net force imbalance that is pulling it into the inside of the turn. That's called centripetal force and it is the horizontal component of lift. There are essentially TWO forces at play when a plane is in a turn. Lift and Weight. At an angle, lift is broken up into its x and y components. The y component essentially needs to offset the weight so that the plane remains at the same altitude and the x component is the centripetal force in this case. There is no other force that is opposing it.
Banked turn - Wikipedia, the free encyclopedia
http://selair.selkirk.ca/Training/Ae...es/lf-turn.gif
oggers:
But it seems you are in denial when it is pointed out that work is being done on the downwash (as CYHeli stated).
You truly are a piece of work!
Here are a couple quotes from myself:
Regarding your parcel of air explanation: as discussed, yes, it requires power to move air. That power comes from the engine. That power is called BHP or SHP. It is not called THP.
Of course you're doing 'work' on the air because you're moving it backwards. And I'd like to add emphasis to the part where I said: "doing 'work' on the air".
That emphasis obviously wasn't enough!
...and now back to a quote from you:
Your argument is a purely semantic one in which you insist on defining THP as that which moves the aircraft.
No, it's not semantics. All the resources I've provided have depicted THP as such. That is what THP is. I have a feeling you REALLY don't like being wrong and are going to continue to fight this point no matter how much I explain that you are in fact not correct on this subject.
Because a helicopter can hover there is an alternative way of determining the efficiency of the rotor system that does not require airspeed of the vehicle.
I highlighted 'alternative' because it is just that. I could analyze efficiency with regard to heat as well... that's called thermal efficiency! But as I've stated quite a number of times - I'm talking about propulsive efficiency.
Markdem:
Are you saying that a wind tunnel (helicopter on it side) does no work when YOU are "MOVED" by standing behind it?
Agreed that the aircraft may not move therefore not doing much work ON IT SELF but still moving a hell lot of air behind it.
Please, read the thread, Markdem. I've stated a few times already, including just above in this post, that you are doing work on the air. But with regard to
aircraft performance, moving air is not what is being analyzed!
rudderrudderrat:
p.e. is not zero.
So even if the aircraft is stationary or the helicopter is hovering, there is definitely THP being produced if you are making SHP.
THP has its own equation - if you want to see if there is THP in a situation, you need to use it. As stated numerous times, if the flight velocity is zero, there is zero THP - that is what the equation says, not me.
This is an expanded form of the p.e. equation -
http://i.imgur.com/NXLV3.png