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Old May 11, 2012, 10:16 PM
USA, CA, Mountain View
Joined Dec 2008
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Question
Prop Type - Any Effect On Gain? UPDATE: RESULTS

If you've tried this, would going from 12 x 3.8 to 12 x 4.7 have any effect on gain or stability? This is for a heavy lift 26" hex. Thanks! Earl
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Last edited by Earl E Adobtr; May 18, 2012 at 07:19 PM.
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Old May 11, 2012, 11:09 PM
The END.....ha!
KCV6's Avatar
Australia, SA, Edinburgh
Joined Aug 2009
5,878 Posts
Earl, I have swapped between props on the quad and the octo (both 4S 3548 size 800Wish per motor) and on both occasions the gain did vary but not by a lot and that was going between 14x4.7 and 12x4.5 so at a guess going same size to a bit more or less pitch may not have a huge effect. Stability didn't change a great deal other than on 14's both of mine have to be loaded up fairly heavy or they get real "floaty" in the breeze. I was thinking of useing the 12's with no load just for back yard practice as they are cheap compared to the APC 14SF's.

From my mucking around I think just changing pitch won't have a great effect on stability. Will be interested to hear how it goes for you if you try it.

Mark
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Old May 12, 2012, 01:28 AM
USA, CA, Mountain View
Joined Dec 2008
615 Posts
Thanks Mark. Appreciate the response. I haven't experimented with props on a hex so your experience with the octo is telling. Turns out a smaller hex I have with 10x4.7 props flies extremely well so I was trying to scale that success up to a heavy lifter. So far it's not panning out and I'm rooting around for the answer.
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Old May 18, 2012, 08:15 PM
USA, CA, Mountain View
Joined Dec 2008
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Results

Awhile back i posed the question whether increasing prop pitch had any effect on gain settings for the HFP board.

It turns out not much. But I learned a few things swapping props, esc's and motors that I'll pass on, for what it's worth.

First, this is a 26" XHex with 2814 Avroto motors and Turnigy Plush 30A esc's. This was not what I started with when I originally asked the question but this is what I ended up with to make it run right.

As far as props go, I started with the old standby APC 12x3.8. Turns out I lost about 4 clicks of gain with these but gained 2 amps of headroom per motor compared to the Gemfan 12x4.5 carbon blades. Switching to Gemfan 11x4.7 and sliding the motors in 2cm on the booms decreased stability dramatically.

Now the real surprise: I was originally running RC Timer 3536/11 motors with RC Timer 50 amp esc's. Swapping these out for the Avroto's and Plush's allowed me to triple my gain setting but I had to switch to 4S batteries to compensate for the slight decrease in power. I just happened to have Avrotos already soldered to the Plush esc's so I swapped them all out as a set. The RC Timer 3535/11's are a well known and well liked motor. I think the RC Timer ESC's were the issue causing the low gain problem.

So, after a full day, the bottom line is the hex is finally running at a decent 74 (setup client) gain @ 4160 grams. Whew!
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Old May 18, 2012, 08:28 PM
The END.....ha!
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Australia, SA, Edinburgh
Joined Aug 2009
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Great info Earl. Good to see you have got things up and running well.

Mark
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Old May 19, 2012, 12:12 PM
USA, CA, Mountain View
Joined Dec 2008
615 Posts
Yeah, you were right on. Now I see why everyone is still using APC. There must be a fair amount of engineering behind them to give me the same throttle position and 2 amps less draw per motor.
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