Thanx guys for taking time to answer
Some remarks
The rules do not alow use of constant speed props
At the moment we are doing 33000 rpm with air speeds up to 330 kph (telemetry) on 180 mm props so mach 1 is reached.
I think I will go for reduction of the diameter with wider blades and reduce the alpha at the tips and hope for better results
I hope the reduced efficiency due to smaler diameter will be made up for by the increased performance of the tip profiles.
Will see what happens.
Robbert
[This message has been edited by robbert (edited 11 January 2001).]