WattFlyer RC Electric Flight Forums - Discuss radio control eflight - View Single Post - Newbie; power system for H9 Funtana X 50?
Old 11-01-2008, 07:40 PM
  #34  
HugoW
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Join Date: Oct 2008
Location: the Netherlands
Posts: 169
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Well, I've just taken another step in the process. The motor in the previous pictures is on the shelf for a less weight-sensitive project, this is it:



This is the new one, it's a Turnigy SK motor:



This motor should be more powerfull, and more efficient in turning amps into thrust. Good combination, since it weighs a lot less, too. So with all parts in the shop, I fitted and wired the lot today:



The clampy thingies (English?) are srewed to the little wood piece, and hold the wires for soldering.



Then the moment of truth, power-up. Everything beeped the way it should (yes, I read the manuals...) so ready for the first try. Damn, prop turns the wrong way. Disconnect everything, power up solder iron again. Then it's time for the second test, and everything works like a charm.

OK, now for some measuring. I bought a Watt's Up meter, since I only need to now upper values, and this meter remembers them. I took of the casing and heat shrink wrapped it, saves a few grams. I migh get an Eagle Tree later, but this Watt's set me back the same amount as the screen of the Eagle Tree alone would, and I prefer to have a screen.

OK, test! Well, this thing has power. I ran a 16x10 prop op, and power peaked at 1.734,7Watt. Yep, that's 1,7kW! Maximum amps was 89,91A, the pack voltage bottomed out at 18,91V. It's a 6S pack, so 3,15V/cell. That's very close to the border of 3,0V. The ESC should be able to cope with 90A peaks for 10 seconds, it's mighty close to that value. The motor is spec'd at 1450W, so I'm way over that. It got warm, too, but I could put my hand on it, but I only ran full power for 3 seconds. The plane weight should be 2600 grams fly-ready, with this power thats 667W/kg. About one and a half times the recommandation for serious 3D. All this was tested static, by the way. I thing I should put on a 15x8 prop and do some more static tests, and use the 15x8 for the first flights.

It was a bit nerveracking, I must say, doing this test with the fuse up side down on the dining table, tail held between two chairs... The dog went berserk, and I held on to the plane thoroughly, despite the fact that is was securely anchored.

I'll post again when I get a hold of a 15x8 prop, but so far, it looks promissing, right?
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