Comparing to a Valach 120cc inline twin.
I have a Valach 120cc inline twin.
It is measured to give 5000 rpm with an Engel 28x14 3 blade propeller.
It powers a 23 kg heavy model quite well.
If one look at the factory spec for the Roto 130 FSI, it says
-2 BLADE PROPELLER 28/10-29/10
-3 BLADE PROPELLER 26/10
That doesnt sound too good.......but it would be good to hear from someone that actually measured.
As mentioned, the Valach 120cc inline twin gave 5000 rpm with an Engel 28x14 3 blade propeller.