I haven't looked too far into the Excalibur's numbers, but does the promised 420 knots top speed (air or ground, anyhow?) account for payload? I read somewhere that it can pack four Hellfires.
IMHO this is a very compromised design. The most obvious problem is the lack of space but this maybe at least manageable. However I think that there are two fields that this is conceptually very compromised.
Firstly the company says that with the electric retractable fans in the wings the main engine can be optimized for cruising in airplane mode. However at least at the prototype stage the main jet engine provides about 70% of the total vertical thrust, so either it is over sized for cruise (with the respective weight and consumption penalties) or the aircraft can barely take off vertically.
The other problem which I think is the most serious one is the transition phase. After the plane take off vertically (just, because as the company said it cannot hover) it has to recline the jet engine, to retract the fans inside the wings and also to roll 180 degrees!. There is a very elaborate maneuver there and the total combined energy of the aircraft (aerodynamic lift from the wings, thrust from the jet engine, thrust from the fans) seems inadequate.
It seems a very complicated concept (maybe unnecessarily).
I'm seeing amazing forward speeds being claimed for this once its developed further, 420kts, can't see it myself.This one is funky enough for Wired ;-)
Comments
Firstly the company says that with the electric retractable fans in the wings the main engine can be optimized for cruising in airplane mode. However at least at the prototype stage the main jet engine provides about 70% of the total vertical thrust, so either it is over sized for cruise (with the respective weight and consumption penalties) or the aircraft can barely take off vertically.
The other problem which I think is the most serious one is the transition phase. After the plane take off vertically (just, because as the company said it cannot hover) it has to recline the jet engine, to retract the fans inside the wings and also to roll 180 degrees!. There is a very elaborate maneuver there and the total combined energy of the aircraft (aerodynamic lift from the wings, thrust from the jet engine, thrust from the fans) seems inadequate.
It seems a very complicated concept (maybe unnecessarily).
Another article from Graham Warwick .