In message , RichH wrote:
Sounds like a prop that has too little pitch/dia. or that the
transmission is slipping badly.

I thought it is a "fixed" transmission, switch a toothweel on or off.

And about the pitch and dia you are right but I notized that there isn't much
speed difference between 2000 and 4000 RPM, thats why I suspect there is a part
missing.

Whats the transmission make? .... Paragon?
There is written " Castoloi " and idrogetti italy, I just found something on
the net about idrogetti, but not this jet.( jet)

Edmund wrote: