Rotodyne Noise

Something I have been meaning to let fly over for some time.
The BBC, is sometimes claimed to be the source of good pronunciation and technical accuracy. They talk of a company called AWgustaWestland and RAf! Culrose but one of their favourite statements concerns the Rotodyne.

On several occasions This incredible step forward in rotorcraft technology, has been described as ‘Deafening’ at two miles. Good tabloid stuff!
Now nobody is going to claim that the Rotodyne noise was acceptable, and those of us who worked in close proximity or were privileged to fly with it, were well aware that we had a major problem on our hands. And a great deal of serious effort was made to assess it and understand it, and hopefully improve it.

Rotodyne was a compound helicopter, it had two regimes of flight:
• The helicopter mode: With all tip-jets burning, and this was indeed noisy.
• Gyroplane mode: Tip-jets OFF, when it became a twin engine turboprop airliner with a rotor in autorotation,

This is no place to go into the extensive work done by Fairey, its all in the National Archive.
Summarized it goes as follows:

• Rotodyne light-up over central London 95phons
• London Traffic on Westminster Bridge 95phons
• London Underground on-board train. 100phons
• London Underground Station platform 103phons
• Cinema, at full blast (Lord of the Rings?) 110phons

During some noise measurements taken during the programme with Rotodyne lighting up at 1000ft, the microphone recorded a bird chirping in the background. Perhaps the BBC should let David Attenborough know about this noisy little devil.

Yes the Rotodyne was noisy, but surely the BBC can find something more substantial to decry British achievements, without resorting to fantasy, or simply get their facts right!