Hi,
Hope I can help,
Your rossi is a great engine.
If we take a (any) fan and calculate the pitch / diameter / rpm.
and then check tailpipe velosity we will know how heavy and wing loading to build the jet.
So if we take the (for instance the Dynamax) if it flys a jet at 21000 rpm then any engine that will turn it at 21000 rpm will work.
I have spent a good part of my life testing (i love jets) An os .91 will do this without to much messing around.
However a Rossi .65 will also do this but it does take a bit of setting up to get it to Idle. I have found that once you get the Rossi to perform it just might out rev the OS.
The only downside is that it takes a .65 longer to reach RPM's than a .91.
However off grass this does not matter because the jet will sit there and not move untill the rpm hit about 18000 then off it goes.
On pavement it will take longer runway because it is rolling whil it is reving up.
If you have a normal mowed grass strip and a regal eagal does not take off in 50 - 70' then please call me. www.rcjets.com
Bob Parkinson