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[Tom Laird]

 Hi,
Does anyone have a feel for what my ballpark max revs should be from a Q80-11S / Spin99 / APC 20.5x14? I am seeing about 5780 (from the Jeti box) which I think is coupled to the lack of power I am seeing. This is over all my battery sets which range from 1 year to 3 years old. My timing is 25 degrees at 8Khz.

I am also getting 6000 from a Biela 21x14 and 6000 from  an APC 21x13WE.

thanks
Tom

[Clive Whitwood]

I'm surprised by the lack of power comment.
Revs sound about right compared with what I am getting on my Q8013Xl with a beila 21 x 14.
I am pulling a max of 70A most flights and have power to spare.
Wonder what you are pulling?

[Tom Laird]

Hi Clive
That is a good data point. Today I am going to fly Fig 9's as a stress test to ascertain the state of the batteries.
cheers
Tom

[Tom Laird]

Hi
4 flights today, 16 fig 9's each. All 7 minutes plus landing. 22 to 25% left in battery. 220 rpm drop between each set of batteries. 660 total between best (6550) and worst (5890). I think it is mostly me getting used to the different characteristics of the Mythos versus the Contrast.

[Tom Laird]

To conclude with an observation: my APC 20.5 x 14 gave 5780 revs on the ground whereas the Biela 20x14* gave 6080 on the ground and 6330 in the air.

On the ground RPM values from the Jeti speed controller, same battery pack with about 10 seconds motor run sequentially:

1st run: APC 20.5 x 14 = 5780
2nd run: Biela 21 x 14 = 6000
3rd run: Biela 20 x 14 = 6080
4th run: APC 21 x 13WE = 6000

* This prop measured 20 1/2 tip to tip when it arrived but a close encounter with our tarmac runway saw it reduce to 20" tip to tip. My latest Biela 21x14 does however measure 21" tip to tip.

[Tom Laird]

Yesterday the snow and rain went off long enough to get some measurements with the Wattmeter. Speedo 1 gave 2300 watts dropping to 1700 after about 5 seconds whereas Speedo 2 gave a constant 2700/2800 watts at 6080 RPM over 3 runs of about 10 seconds each so I think the conclusion is fairly obvious. I will send Speedo 1 away for investigation and hopefully a repair.