I notice on the Sikorsky artist impressions that they show streamlined rotor masts. Presumably to reduce parasite drag.
Yes. It is mentioned that the rotors and masts were 50% of the drag on the earlier XH-59A ABC. The president of Sikorsky has said that this drag on the X2 will be slightly above 25%.
The height between each disc also seems to have been reduced. Is this due to the "rigid rotor" setup mentioned?
Yes. The rotors are very rigid. The
Advancing Blade Concept (ABC) puts the majority of the lift on the advancing blades during forward flight. This causes the lower advancing blade tips to rise toward the upper rotor's retreating blades. The maximum allowable clearance between the blade tips of the XH-59A was 13", as I recall.
"Two rotors are like two women in the kitchen. You might think they would do twice as much work, but the efficiency of each is lower-ed by 35 percent." -- Igor Sikorsky
No. This is not true for the Side-by-side, Interleaving, Intermeshing and Tandem configurations. In fact, it is not even true for the coaxial configuration when the total number of blades is the same on both craft.
Dave