• I have a new Y6 build with 880Kv motors. Based on some reading I've done, the higher Kv motors are better with smaller props. Would 10s all around be suitable for this, or could I potentially go even smaller on top or bottom for a performance boost?

    • Long-winded information dump on props:

      In very generalized terms, smaller props tend to be used for higher speeds.  At a given speed (ii.e. a given KV motor at a given battery voltage), the smaller prop will consume fewer amps than a larger prop.  It is important to keep the amperage draw low enough that you don't exceed the capability of the Electronic Speed Control (ESC) controlling that motor.  The faster spin of the prop may allow greater maximum airspeed; typically at a lower thrust.  So, you typically end up with a faster top speed, but not as much thrust for things like rapid changes of direction.  

      Additional caveats include:  You can also start talking about varying prop pitch (the second number, like 4.7), too, which has even more to do with top speed and only a little to do with thrust.  Larger diameter props are expected to be more efficient than smaller diameter ones in the same way a long wingspan wing is expected to be more efficient than a short one.  

      Larger diameter props will give more of a torque reaction as they accelerate or decelerate.  That torque reaction is what the Y6  uses for yaw control.  

      So, if you are looking to maximize top speed, you could try to find the correct pitch in a 9" prop.  To be honest, I don't think I've ever flown mine at its true top speed.  I do enjoy rapid acceleration from time to time (i.e. thrust), but these things are just stupid fast already for what I use mine for.  

      If the machine is new to you, you will likely scrape up or destroy a good number of props with tip-overs on landing. You will be replacing the first set or two within days (unless that's just me being a crappy pilot).

      Props are cheap and you will be replacing them often anyway.  I've probably ruined 20 props in the first three months. I buy them in packs of 6 (6 for the top motors and 6 for the bottom rotors).  There are few things more comforting than a box full of spare props.  :)

      The testing done with the 10/11 combo vs. 10/10 suggests little benefit to staggered sizes.  As noted above, I'd prefer the smaller size of the machine overall; mostly for packing and transport.  So, I wouldn't bother staggering the prop sizes.  If 9's work, use all 9's.  I would then drill additional holes for the landing gear so I could scoot them half an inch out for use with 10's or 1" out for 9's.  Wider is better for landing gear, for sure, just marginally.  

      So, there are the vague facts.  I'd set it up with 10's initially.  If you want to experiment with 9's, you need an amp meter to check the power coming into the ESC. You can rig a test stand to a spare motor and spare ESC to measure the motor amp draw with various props.  Flitetest had a demonstration on this for which they used a lever arm resting on a scale to measure thrust at the same time.  At 3 minutes into this video, you will see them use it:  Flitetest has great info in their beginner series.  

      Of course we would all like to know the results.  

    • Thank you Haygood. That's lots of good info for me.

      I have had the same experience as you with respect to props - my prop consumption rate over the first two weeks of flight is about 1 every 15 minutes of flying. :) I'm actually flying with 2 10s and 1 11 on top right now, as I ran out of spare 10" SFPs. It doesn't seem to have an observable impact.

      I have 30A ESCs, and had assumed I'd have lots of head room with those, but I'll keep an eye on the current draw as I change things up.

      It seems intuitive to me that a steeper pitch on the bottom would make sense, since those props are in the downwash of the ones above. One already needs to go with different props on top and bottom on a Y6B due to SFP vs. SF, so maybe I'll try all 10s with a steeper pitch on the bottom and see how that works.

      Of course, much of this stuff is counter-intuitive to me, so experimenting will be necessary, and fun.

  • I do appreciate the machine being every bit as small as it can be using the tens.
  • I did a lot of reading on here as well as RCG on this matter since I'm building a Y6 at the moment.  Conclusion in general:  Nice thought but the lack of meaningful improvements is outweighed by the simplicity of the same size all around.

    • to add, the 11" props stress to the bottom motors & esc's more than the top. specially on the 850 motors. I'm running 800kv t-motors on my 3dr y6, with 11" props all around. 20-22 amp hover.

  • If you dig around the Y6 Group in DIY Drones and the APM forums you will find at least two discussions on this. From what I've read posted by people who have tested and based on my own experiences...Here what I have gathered...

    its to my understanding that originally the idea of having 10s on top and 11s on the bottom, is that the 11s could get "cleaner" air as it pulled it down around the outside of the upper 10s. After actual testing it was determined that there wasnt much of a benefit and that using 10s all around was adopted out of convenience. I used 10s/11s when I first built mine had a crash and have used 10s all around since then.  

    In regards to battery, I can tell you my 3DR Y6 flies alot better on a 4s 6000 then on 3s. 

    Hope this helps

  • I don't think propeller size is related to motor number assignment.  As long as you have pusher props on the bottom and normal props on the top, the size shouldn't matter.  I think the use of 10's all around might be related to the use of 4s batteries on the typical 2014 build more than the configuration/assignment of which motor goes by which number/name.  I didn't look into testing done on 3s's because I use 4s batteries.  I see Jaime referencing Robert's testing below, which should inform you on prop choice.  But, to answer the question, Y6B shouldn't care which size you use any more than Y6A did.

    I use 10's all around on my 2014.  A fringe benefit was I was able to move the landing gear outboard 1/2".  In theory this makes the craft 8% more stable on the ground, so I might bend 8% fewer props?!?!?  Ha.  We'll see.  I just drilled a third set of holes in each arm and scooted the landing gear over half an inch.  This also puts the landing gear slightly further from the GoPro, so I'm less likely to see a foot dangling in the picture.

    • SFP are pusher props right? I put those on the top per 3DR assembly instructions, SF on bottom.

      I've had my Y6 going for about a month and also buy in sets of 6 props each from Ebay (APC 10 x 4.7). I'm getting better though, and am very good a balancing props now.

  • I have been flying Y6B with 11x4.7 at the bottom without issue. But I think there was some testing done on the propeller sizes a few months ago and the conclusion was that 10s on both motors is the recommendation. I think Robert Lefebvre did the testing.

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