What does this prop combination mean ?

I am having issues with my quadcopter in that it is taking about 70% throttle to hover. it was working fine before on the same weight but different motors and props. After replacing almost all components over the past two months (as i did not know the root cause), I believe the issue may be new motors and props i bought. I bought these motors and these props. Now the motor spec recommends 12X45 as opposed to the 11X50 i bought. Does this explain the significant power loss i am experiencing ?

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  • i'd buy APC only props, not clones, they can lift 50-100gr more then cheap clones.

  • I had a similar problem moving from 11x4.7 slow fly props to carbon fiber 11x5 electric style. There appeared to not be enough lift to take off with the 11x5 electric style. Seems strange I know. I was using 2830 800Kv (300W) NTM crappy motors on 3S.

    Moved up to 12x47 SF props and everything was great again.

    good luck figuring it out.


    • i am having trouble finding 

      12x4.5 Carbon Fiber Propellers with a 4mm adaptor in the uk if anyone has a link, that would be great.

    • Not specifically the UK.... http://flyduino.net/propeller-carbon-fibre-glass  The Gemfan AP props are my favourites, but the HQ are good and Tiger are the bomb (if you an afford it).

  • MR60


    You have practically no differences between your old and new setup,  so you should not experience any throttle difference except if you also changed other things like fc, ESC, battery,...?

    I would not fly anyway with these motors and the 12x45 props, in a 4S config, as you motors will overheat.

    Your issue has probably more to do with your APM parameters throttle config or radio calibration (not using the full PWM range)

    Side note: yes you will get more thrust with higher pitches but you will consume more amps (loose flight time and motors heating more); the optimum ration is pitch=1/3 of prop diameter.

    • so - i haven't changed anything except made it lighter. it must be the props causing the issue?

  • A simple test would be to put a set of the 12x45 props on the new motors and measure the difference. And yes there will be a difference. Not even looking at the difference in the motors so lets assume they are the same output per unit of energy input then you have changed both the size of the prop making it smaller so it would need to spin faster but you have also changed the slant of the props. There are going to be performance changes going between aslant of x45 and an x50 within the same prop size. As a final note: there can be a change in performance with props in the same size and slant but made of different material when the firmness of the prop is effected. 

    By going back to the same 12x45 props you will be able to measure the performance of the engines per unit of energy input. Right now you have to many variables to accurately measure why your thrust is lower. All you can measure is that your thrust is lower and them only by an empirical amount not a measured amount. 

    • yes , i will certainly compare the two. thanks

    • Rob has the right idea..  definitely try the 12x45... worth noting, those graupner style props in high pitch are not well suited to hovering, they are better in fast forward flight such as acrobatic manoeuvres, but you will find for hovering, that lower pitch props are more efficient and 'grip' more..   if you take a look at the way T-Motor is going with their props, they are decreasing pitch rather than increasing, to optimise lift efficiency.

  • Can you provide some more information about your setup? Take off weight (with battery), battery type and size. What was the previous motor/prop combination you had on this craft. 

    Can you outline what troubleshooting steps you have performed? Such as ESC calibration, radio calibration, etc?

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