I have the RD1-c gearbox so bar rpm will be 2456 if and only if I can get there with my non-tuned intake & exhaust.

1350mm x 90mm is 53.15”x3.542”

72" and 75” is way too long, according to the spreadsheet I’d be lucky to get 1300 prop rpm. the biggest I would attempt with the Renesis is 1500x100mm or 59.055”x3.937”, I apologise for the earlier confusion, I’m Australian and work best with metrics.

the calculation is over my head also, I just copied it from the spreadsheet. it lost formatting in the copy paste, the 3 & 5 are power of. X section = width.

Longer, thicker bars would only be useful if you wanted to plot hp at lower rpm or could produce more Hp than I’m expecting. I just need a load on the engine to run it, thought I may as well have something that gives a result, whether it is accurate or not is immaterial, if changes to the engine result in higher rpm= progress, lower rpm = regression.

Andrew martin