In article , Keith Willshaw
writes
Its flight tests were succesful and it lifted a respectable load, its
real limitation, as with any helicopter is top speed. Due to the
problems of imbalanced lift between advancing and lagging rotors
it will never match a fixed wing aircraft for speed.

Didn't it carry a load of passengers to the Paris airshow from London,
can't remember but something like 20-30 people?

During development they kept reducing the wing angle as they found the
rotor continued to provide most of the lift. As they did this, speed
increased, I'm not sure if they got as far as finding the optimum
configuration.

--
John