Originally Posted by
Chu Chu
Energy transfer doesn't seem like the whole explanation.
I would say that energy transfer is the whole story, but not the only story
What I mean is that many phenomena have more than one explanation, from different aspects,
simultaneously, of what's going on. For example, rocket propulsion can be explained either by conservation of momentum (mass times velocity of the expelled propellants must equal the mass times velocity of the vehicle going the other way)
or unbalanced force (pressure of the hot propellants at the nozzle times its). Both ways account for the phenomenon 100%, but looking at it different ways. Another example (not to derail this on a tangent) is the multitude of explanations for the lift of a wing. People who champion one of them, but understanding (at least somewhat) some of the others, get bent into pretzels in considering how much each one contributes to lift, where they all actually contribute 100%. Or, what makes a car go? Is it he combustion of fuel and oxidizer in the cylinders, or the compressive force on the connecting rods, or the torque on the driveshaft, or the friction of the tires, etc.? Which camp do you fall into?
Anyway here, we have the energy transfer view, and also the the particular forces (as a result of the flow vectors and AOA on the blades that you detailed, and with which I agree completely).
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As for the seized jet rotor drag. Now two separate guys are grasping at muddy memories of ETOPS data saying overall drag may be greater on a seized rotor, so I'm prepared to change my position. Dave Therhino brought up the notion of airflow spilling over the inlet inside-to-outside making its own drag, and I suppose it's possible that in the sized case that drag contribution could outweigh the savings of the reduce drag on the rotor itself.