Hi guys,
Has anyone compared a stiff prop (wood or CF) to the slightly flexible APC or MAS as it relates to amp draw? I know for glow very stiff props are preferred but for electric we use thinner blade designs mostly from APC or MAS. There are some wood (Bad Ass) but not sure if they offer very thin blades that are as stiff as the normal glow prop. My first thought is that the thin blade electric's with undercamber may pull more out of a corner that may make up for the flex in the blade but I have not done back-to-back test flights. Anyone try this and see any difference in amp draw and performance?

Best, DennisT

Amp draw is a result of prop efficiency, which is mostly a function of prop shape. The electric APCs I used were very efficient, but so flexible that they made noise in corners.

My guess is that good electric stunt props have maximum efficiency at a speed less than level-flight cruising speed and drop off in efficiency as speed increases, yet have sufficiently high maximum efficiency that they don't require immense batteries. Although anybody can make a crummy prop that uses a lot of electricity, the very best electric stunt prop (so I've heard) is notorious for using a lot of electricity.

As for stiffness, most folks use stiff carbon props. Andrey Yatsenko uses aeroelastically tailored wood props, which he says are better. Good luck finding such props at your local hobby shop.

It was not apples/oranges (I wonder why we would use a fruit to power a plane?) but I have one non-scientific observation.  A friend lent me one of Igor's three blade props to replace the 12-6 BadAss I was using.  I changed from a MAS three blade 11-6 to the BA two blade 12-6.  Everything was better including battery usage and cornering.  When I put on Igor's prop I was amazed at how much better corners and overhead maneuvers were BUT, and this is a big but - it drew 400ma more and ran a Li-Ion battery to where it took 2850 ma to recharge a 2800 battery.  It did this on two batteries.  Both recharged and appear undamaged but Wow, is that even possible?  For now, I am sticking with the two blade props.  The APC props I have are the easiest on the battery and the wallet.  They do sing a bit in the corners, but it doesn't bother me or apparently the plane either.   

Ken

What I am wondering is if the prop flexes I am told it de-pitches some till they flex back. On glow that would allow a pop in rpm, for electric what it might do is ease the load but might slow a little? Maybe the stiff wood prop with some under camber sanded in could help reduce this?

Best,   DennisT

Quote from: Howard Rush on December 14, 2025, 11:19:26 PM
My guess is that good electric stunt props have maximum efficiency at a speed less than level-flight cruising speed and drop off in efficiency as speed increases, yet have sufficiently high maximum efficiency that they don't require immense batteries.

Does this person mean thrust, rather than efficiency?  I suspect he doesn't know what he's talking about.

I'm sold on APC-E series props for all electric applications. The airfoil and blade cord distribution is optimized for E-power. The limitation is a size you want may not exist in a left hand application (or right hand for that matter). I was looking for a bit more speed and "headroom" for the governor using an APC 11 X 5.5 EP so I tried a Badass 11 X 6 (Left Hand). It broke on the first landing which was fine as it was a total dud. I got less, a lot less. Less current, less speed, less line tension... Ended up with shorter lines to get the speed up and back down the RPM for Climb/Dive Headroom.

Cheers,

Steve M.

Steve,
What plane/motor are you running and what rpm? I have been testing a BA 2815 980Kv turning a MAS 10x7 at 10K and it is just about perfect on my 33oz Ringmaster, using only 1150mah out of 4S 1800mah pack. I want to try a MAS 10x8 de-pitched to 7 (match the original 10x7) to get a little wider blade and see if it gives a little more up top. The MAS 10x8 has about 1/16" wider blade than the 10x7 and when I flew it (at the factory 8" pitch), it was like a JATO bottle went off, a little too much (speed jumped from 55 to 66mph). The BA 2815  980Kv with the MAS10x7 setup is like a Fox 35 on super fuel with a Top Flite 10x6 prop. With the wider blade I hope it will be like running an OS FP40 on a Rev-up10x6EW, more pull through and line tension without to wind up in the wind.

Best,   DennisT

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