Hi Everyone

My name is Keith Lawes. I'm technical director RCV

Simple answer to your question is that the 120 could swing a much larger multi blade prop but at the time we specified them there didnt seem to be anything readily availble. If there is anything available now then we would be interested to hear about it.

Also in general if you can fit a two blader it will be significantly more efficient.

You can put the same prop on both 90 and 120SP engines, but the 120 will give you more RPM for a given prop and therefore more power. The rev range figures are a little misleading as in general the 90 will be towards the lower and the 120 the upper.

Prop RPM v power is a cube law, i.e. to double your RPM needs 2x2x2 = 8x the power. So you dont need a very big increase in RPM between the two engines to give you significantly more power and performance:- If the 90SP swings a prop at 5000RPM and the 120 swings it at 5500RPM, its giving roungly 30% more power ((5500/5000) cubed!).

Hope this helps

Keith