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Old Aug 18, 2012, 08:54 AM
c131frdave is offline
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Too many numbers
United States, IL, Lake in the Hills
Joined Oct 2010
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Check me please

Hello. I'm trying to figure out my setup for a new Sbach airplane. It is designed for a 30cc gas or equivilent.

I'm trying to make sure it will be a decent 3D airplane.

Airframe: 4500g
Motor: 1150g
10S batt: 1283g
Servos: 300g
ESC: 165g
Prop: 77g
Spinner: 130g
Misc: 200g

Total: 7800g (approx)

That would be about 17 pounds. Somewhere I read that a good 3D airplane has 150 watts/pound, or in this case, 2550 watts (3.4 hp).

The motor I chose is a 2960 watt motor that is supposed to emulate a standard 3.9hp gas engine, so I think I have a good setup here.

What am I missing? Any suggestions?

Thanks.
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Old Aug 18, 2012, 09:57 AM
racin06 is offline
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United States, IN, Indianapolis
Joined Dec 2006
2,417 Posts
So, what is the airplane? What is the wingspan? Typically, a 30cc sized airplane has a wingspan in the 72-75" range. 17 lbs is very heavy for these airplanes...usually in the 11 - 11.5 lb range. 17 lbs would normally be a 50cc sized airplane...85" - 90" wingspan. Also, 150 watts/lb is the bare minimum for 3D. IMO, you need 200+ watts/lb..225+ watts/lb for extreme 3D.
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Old Aug 18, 2012, 12:55 PM
c131frdave is offline
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Too many numbers
United States, IL, Lake in the Hills
Joined Oct 2010
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Actually, I think I misread the weight. I think the 4500G (it says 4200 actually) is supposed to be flying weight with a 30CC gas and fuel. I assume electric weighs about the same, so that would be about 10 pounds...

You tell me. This is the kit in question though there are a few very similiar I am looking at.
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Old Aug 18, 2012, 01:06 PM
racin06 is offline
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United States, IN, Indianapolis
Joined Dec 2006
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Ok, yes, that's a 73" airplane. You will be good to go with a 2900 watt motor on a 10 lb airplane. Actually, the electrics weigh a little more than the gasoline setups.
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Old Aug 18, 2012, 01:16 PM
c131frdave is offline
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Too many numbers
United States, IL, Lake in the Hills
Joined Oct 2010
1,895 Posts
If you add up my list minus the airframe, you come up with about 3300 grams. So the airframe only weighs 900 grams (less than the lipos by 1/3)??
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Old Aug 19, 2012, 02:16 PM
dirtyballs is offline
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Bart
Netherlands
Joined Oct 2010
298 Posts
your setup is more for a 88" aircraft not for a 73
my engine on a 2meter sebart SU 29s is 430 gram on 6s

don't recommended it it is real on the edge. so go for a 600 gram on 8s
Look and you will find, keep it light you won't regret it , it flies a lot better.

Sebart SU29S monster 3D 3.9 kg on 6s (5 min 47 sec)



DB
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