The original 'Type Y' Rotodyne was indeed very noisy when in helicopter mode with the tip jets lit. But when fitted with the 'Type 8c' tip jet silencers, noise was substantially reduced in this mode, such that the trials into Battersea heliport received not a single noise complaint. When cruising in gyroplane mode, the tip jets were not lit and the noise level was no worse than turboprop aircraft of the day.
By the time of cancellation, even greater progress had been made with noise reduction; one promising development for the production 'Type Z' version used 9 small jets embedded in the tip end of each blade. It was tested on the White Waltham rig with excellent results......but then the programme was cancelled.
BEA had originally specified a 40 passenger version; by the time of cancellation this had increased to 57 (or 70 in high density seating) for the 'Type Z', which would have had Rolls-Royce engines rather than the inadequate Napier Eland.
Another ground-breaking British aircraft which should have been a great success, but was never allowed to show its real potential.