Guys, lets keep a nice peace-ible debate!
Both tilt-rotor and advancing-blade have their reasons for being, and fascinating history of concept development. To my mind the advantage of ABC is a very compact configuration, and the ability to autorotate from any flight regime without relying on stored hydraulic energy - i'm not sure what the system is in V-22 during transition.
Dave, are you sure about those figures? If you mean HP/lb then it makes sense. Advancing-blade should have a lower disc loading over tilt-rotor.
Both concepts will lose out to a conventional because they must carry extra mass to accomplish cruise speed. Also the blade radius, planform & twist will be suited to a higher cruise speed.
I've no problem with argueing the merits, but let X2 step up to the mark first. Another perfectly good flying machine, Space Shuttle, is being grounded because the Columbia accident review board thought it would be a good idea to force re-certification on a 30 year old design. I'd hate to see a good concept like X2 quashed because the engineers weren't given the opportunity to get everything just so...
