125cm to 130cm. Is bigger really better, and by how much.

[notch]

I have a 1400mm caged PA125 (very similar to the ROS125), and feel the need for more power.

Yes too many pies (or beers, not sure which).

Anyone know how much extra push you get from a bigger prop? Tossing up between a powerplant transplant (Moster 185 - yeah baby) in the same cage, or a larger prop for the 125.

I'm guessing the larger prop is going to increase the chance of prop strike too.

[norbertflyer]

If you need a significant increase in thrust, swap the engine.

Props are a massive subject and there's loads on the web about prop length/width/pitch to read about before doing anything.

My basic understanding is if the 125 prop's present max revs is at the top of the engines torque curve, then that is at the optimum for max thrust and that is what should be aimed for with a new longer prop. ie the pitch/width must also be changed to suit the extra length. If this can be done with the help of the prop/engine manufacturers, then there will be a slight increase in prop efficiency (therefore thrust) by increasing the prop length. By what amount?, I'm not sure.

If the 125 prop's present max revs is NOT at the top of the engines torque curve, then that needs looking at with the new longer prop design to maximise the thrust.

Be careful though, you could end up with less thrust by increasing prop length without regard to engine peak torque/revs and prop pitch/width.

Richard

[Farmer_Dave]

15 TO 20% more is what I found. But they were different set ups but both at 26 hp. It bumped up the climb rate from 425 ft/min to 565 ft/min. Quite usefull if you need it. Be carefull if you dont