Mike,

There are not a whole lot of 3/4 blade props out there that I am aware of for E (not that you couldn't use a glow 3/4 blade).

With glow, the practical options for increasing downline braking are limited, and extra blades can be quite effective at increasing downline braking - but - it comes at the expense of efficiency. For a given amount of input power, less speed and thrust will be generated (assuming all other design parameters of the prop are equal) - quite simply, 1 big wing is more efficient that 2 or more smaller ones. Some of the speed/pylon guys use a counterbalanced 1 blade prop seeking maximum efficiency and speed, but for most applications, the small increase in efficiency is not worth the hassles (ground clearance, balance, lack of 1 bladed hubs, props, etc).

With glow, less efficiency at the prop generally means running higher throttle more often, and consuming a little more fuel (no big deal, assuming top speed and thrust were more than needed with the 2 blade setup).

With electric, less efficiency means using more amps......generating more heat....and increasing the load on the whole system - not a problem if accounted for in the setup, but it will still be less efficient (which generally translates to more weight and/or shorter lifecycle on the batteries). With electric, there is the option of using the brake on the ESC to control downline speeds, and this does not compromise the choice of prop for best speed / thrust. If the downline speed can not be slowed enough with the ESC brake, then revisiting the propeller is in order, but I've yet to see an electric that responded better with a 3 blade higher pitch prop than a flatter 2 blade prop. Granted I've done very little running of 3 blades on the electrics, but I don't plan to until I think electric is at the point where adding load to the system will have negligible effect on the longevity of the batteries.

Regards,

Dave