Originally Posted by NickLappos
The 2 rotor speed strategy for the ABC was a product of the fact that the rotor is a big vibration machine, and its stability, as well as the response of the fuselage to its forcing function are very hard to understand and control over a broad continuous speed range. Settling on two Nr settings, and allowing only transient operations between vastly simplifies the problem.
Nick, I can definately understand why for what was already an innovative machine the 2 speed option was chosen as carrying the fewest risks. FEA techniques will have moved on since the S-69 was designed, with the possibility of coupled models using aerodynamics and forced modal response. With accelerometer and gyro feedback allowing vibration reduction of rotor dynamics, i would be interested to see how the X2 control system evolves.
Originally Posted by DaveJackson
Aircraft operate within an aerodynamic medium. Vibration and weight, plus the resulting structural problems, are nothing more than undesired byproducts of imperfect aerodynamics.
Dave, if it flies like a dream for 10 hours then suffers fatigue failure by wing/pylon torsional modes it is no good. I agree with the concept of perfect aerodynamics, but it has to work. In truth i don't understand why many of your concepts are so much technically better than anything else. The rotorcraft is a collection of compromises, and can never be the "perfect flying machine". Many specialists from various disciplines coming together solve the problems to improve the resulting compromise, but compromise it must always remain.
Why not prove Independant Root and Tip Control, then demonstrate some test results applied to various symetrical rotorcraft. This will push the envelope, and lead to the next set of compromises to overcome.
Originally Posted by DaveJackson
What have the financially endowed done to significantly improve VTOL craft?
When X2 does fly, it will be a significant contribution to manned flight. I dare say there are all sorts of difficulties to overcome - first flight by Nov was ambitious. In the interim SAS and FBW will significantly contribute to the reduction of accidents in marginal conditions.
Besides are you seriously telling me that the ultimate VTOL the Grumman LM didn't inspire a generation?
Mart