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Old Nov 26, 2012, 07:54 AM
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United Kingdom, Bracknell
Joined Nov 2000
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ESC ratings and Graupner props

We recently had a discussion here on ESC ratings, so I thought I'd share the results of some testing I did today.

I'm flying an F550 with Torxpower 2216 900 Kv motors on 3S 5800 Turnigy 'blue' cells (not Nano-Tech). AUW is 2.1 kg (with gimbal, camera, vtx, landing gear, and dome). Currently I'm using Graupner 10x5 E props, but I've got some 11x5s (with 5mm removed from each blade tip to fit the F550) to try.

I wanted to find out the current prop rpm and amps in the hover, to compare against when I fitted the 11x5s.

So ... hover current shows around 25A. Out of interest I did some full throttle climbs and pullups and the highest reading I could get was 49-50A (of course the Naza restricts power to give a maximum climb rate of 6 metres/second). I know my telemetry over-reads by about 6% on current, so corrected those would be around 24A hover and 48A peak. Max current is therefore 8A per motor ... which confirms the 18A ESCs I have are more than big enough.

On the batteries, the peak current draw works out at 8.3C ... which is pretty comfortable for a 25C continuous / 30C burst pack

Now the really interesting bit

When I tach'd the props to get hover RPM I found that the motors with "L" props (2, 4, and 6 on the Naza) were turning at approx. 5,500 rpm ... but the others were turning at around 6,200 rpm!

Now the torque must be matched or the F550 would have been spinning on the spot, therefore the left and right-rotating versions must have slightly different pitches

Will be interesting to see what the results from the 11x5s are (I still need to balance those before fitting them).
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