My UAP2 Y6

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My UAP2 Y6

Postby SuperSharpShooter » Fri Apr 26, 2013 11:14 am

I've finally got this built into the final configuration it will have. I previously had the ESCs in between the main frame plates and the 3 wires from the ESCs to the motors inside the arms, but the heat they generated collected in the dome, and heated it up to ~50+ deg c, so I just rewired to have the ESCs on the arms. The excess wire I removed weighed over 100g so there was a good saving made.

Motors are sunnysky 2814-11
Props APC 12x3.8 top, 12x6E bottom with the rear pair of motors turning the opposite directions to the front, and the rear pair are also tilted about 2 degrees anticlockwise.

The brushless gimbal is running an Alexmos board, with rctimer 5010 motors, and the gimbal is handmade from 15mm wide aluminium bar.

I should probably redo the dynamic calibration since there have been a lot of changes since it was first done. I'm having trouble getting position hold to hold accurately, there is a small amount of wandering laterally, and in altitude, so hopefully redoing this will help.

Image
-Glenn
SuperSharpShooter
 
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Re: My UAP2 Y6

Postby Max » Fri Apr 26, 2013 11:43 am

Very nice Glenn! Interesting prop combo... I know about running different pitch props top/bottom in coax setups, but never considered/heard of using different types too (SF vs. E). How do you like it, and have you compared to running all same props?

The tilt is to compensate for yaw imbalance because of the different props?

Thanks,
-Max
Max
 
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Re: My UAP2 Y6

Postby SuperSharpShooter » Fri Apr 26, 2013 12:28 pm

Thanks, yeah from what I found, the bottom prop would normally be 15-20% inefficient, and this combo had been recommended. The E props have a reduced profile compared to the SFs, and are a lot stiffer so I figured it might work out well to get both motors doing a closer to equal equal amount of work. I haven't tried with 12x3.8s all round. It would be interesting to try with a 12x6 SF on the bottom. Do you know if yaw is relative to the thrust produced by the prop, or the mass x rpm of the prop and motor?

The tilt compensates the yaw imbalance. Currently I think the front two top (clockwise) motors must be contributing most to yaw. Without the tilt, my LOG_MOT_YAW sits at around 100, and some motors work much harder than others, and get much hotter. With the tilt they all end up being around the same temp after a flight and the LOG_MOT_YAW is around 0. I wonder how this tilt affects the general handling of roll & pitch movements though...

I think there would be more of a yaw imbalance running all the same prop due to the inefficiency of the lowers?
-Glenn
SuperSharpShooter
 
Posts: 276
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Re: My UAP2 Y6

Postby SuperSharpShooter » Mon Apr 29, 2013 12:19 pm

After reading the new motor mix table doc, it's made me wonder if I should try and tune the yaw imbalance out through the yaw parameter in the mixing table rather than with the tilted motor pair... Might try it.
-Glenn
SuperSharpShooter
 
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