Originally Posted by
noneofyourbusiness
The Army has now started looking into what they want as a future heavy lift helicopter. Defiant could only lift half what the Valor lifted, and Sikorsky's president said X2 technology would not make a good heavy lift helicopter. So the Army has three choices. An upgraded Chinook, but the Army has seemed lukewarm to this idea. A Sikorsky CH-53K, but the CH53 series has never been able to displace the Boeing Chinook. Or a tiltrotor, if the Army wants speed and range. All of the big three will propose a tiltrotor if the Army requirement is for higher speed.
I don't think it's true that Defiant could only lift half of what Valor can. They have similar installed power and gross weight, but Defiant has lower disk loading (counting the coaxial system as a single disk of 8 blades). It will fundamentally be more efficient at turning engine power into lift in a hover than a tilt rotor with higher disk loading and increased download due to the wing. There are lots of things to criticize X-2 aircraft on, but hover capability isn't one of them. Smoothly flying forward from a hover or yaw authority in a hover, certainly, lol.
In any case, X-2 technology doesn't scale to the heavy lift class because of the rotor loads, structure, and vibrations problems scale faster than the aircraft does. Since Bell's winged Invictus was selected, perhaps the Army is taking another look at lift compounded helicopters. BV-347 tested out lift compounding on the CH-47 platform (along with 4 bladed rotors and increased rotor separation). Combined with the drag clean up work on the BV-360, it's possible that a modern winged tandem could be attractive to the Army. Less top speed than a tilt rotor, but more longitudinal CG control for external lift operations. Still, if the Army wants a heavy lifter to match the range and speed of their V-280's, the tilt rotor configuration will be the baseline to compare to.