Mart said;
"Let's face it no one else has even tried to push a helicopter to 250kts."
Leishman holds the Minta Martin Chair of Engineering and is a Professor of Aerospace Engineering at the University of Maryland. His new book is showing that he is not an enthusiastic proponent of the tiltwing.
Here is one unflattering statement. ~
"at its maximum gross weight, the V-22 cruises at a true airspeeds closer to 220-250 kts (not 300 kts as superciliously claimed in various sources, including the manufacturer's own publicity materials) at altitudes of above 4,000 feet," ~
Source THTF - page 21