This may be a silly question - but why does the V22 not have it's engines horizontally mounted over or under the wing roots driving the rotors by shafts and gearboxes that I presume it already has for cross coupling?
This would avoid having to tilt the engines and make FOD ingestion easier to handle, reduce the weight slung a long way outboard and probably ease maintenance.
I await the incoming flak for not seeing the obvious.............
bast0n,
That's actually quite a good question, so you'll get no flak here. And there have been some recent tilt-rotor designs proposed with just such a drivetrain configuration. The primary advantage of this arrangement is that the engine (and its lube system) would not be required to operate at various attitudes. The disadvantages are that this configuration is a bit more complex (requiring an additional set of bevel gearboxes), and the interconnect driveshafts would be required to handle 100% of single rotor torque for the life of the drivetrain, thus these parts would be much heavier. The current V-22 interconnect system is only required to handle something like 55% of single engine OEI power for a brief period. For the large majority of its life, the V-22 interconnect system is only required to transmit a very small amount power, likely less than 5% of single engine MRP.
While designing a tilt rotor drivetrain like you propose is quite possible, getting the interconnect driveshaft system design safe and reliable would take some work.
Regards,
riff_raff