I'm interested in how CR props work! On a mechanical level I can visualise some sort of planetary gear lash-up to effect reverse rotation off the crankshaft; but I am stumped by the thought of the 2nd prop (ie the one nearest the engine) taking bites out of an airflow disturbed by the 1st prop which bites into "clean" air! Doesn't this result in a real mess of an airflow? perhaps this aerodynamic conflict explains the racket which the "Bear" created? Perhaps not. Also, I find Bernoulli counter-intuitive, in that I think of lift being created when a control surface projects into the airflow and the pressure of that airflow pushes against it, forcing the wing up (eg in the case of an aileron). I also think of a propellor in the old sense, ie an "air-screw", biting its way through the air like a boat's screw through water. On reflection, when I see a boat's prop spinning, there appears to be an area of air behind it, so is this the vaunted area of lower pressure which is the source of propulsion? can hydrodynamics be akin to aerodynamics? are air and water different as a matter of density only or by a lot more? Why do we have NOTAR and not CR rotors a la Kamov? why does the BAE 146 have 4 engines and the 777 get away with 2? Finally, when the Pakistan earthquake hit and they were crying out for helos, where were the Mi-8's etc from India, Russia and China? Am I being naive (yes) but wouldn't a multi-national helo task force for disasters be great? What could be better, challenging flying but not in combat, but to save lives!! Ah well, dream on.
