Originally Posted by
The Sultan
SD
... You of all should know that when battling excessive drag adding more power is a losing proposition relative to fuel consumption/range and in this case significantly higher vibratory levels/loads.
True, but adding more power to Raider-X will increase the top end speed and that appears to be what Sikorsky is selling, and they’re right in a way. With additional installed power, Raider-X can achieve speeds that the Model 360 cannot because the wing/rotor combination will cease to become an effective source of forward thrust long before the prop does. Of course, at the Army’s target cruise speed of 180 knots, this isn’t true, and a well designed single main rotor is sufficient.
The mass and cost penalty of a lift sharing wing and SPU is likely far less than an entire additional main rotor and controls, a high power clutched propellor, and the additional structure/systems required to sustain and mitigate the loads from the rigid rotors. In other words, the empty weight of Raider-X is bound to be higher than Model 360. Since the Army has requested a max gross weight and limited the rotor diameter, Sikorsky’s ship likely has less payload/fuel than the Model 360 at the customer requested max gross weight. To carry the full payload at the desired range, they’ll have to fly Raider-X at higher gross weights and disk loading which then incurs additional structural penalties unless they choose to have lower maneuver margins at those gross weights. Adding more power just compounds those issues.
Seems like a lot of downside for a little more speed.