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Old Jul 12, 2012, 02:09 PM
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Pop wing won't stay up ?


I just finished the large pop wing 35. I"m having a problem deciphering the electric motor sizes. It calls for a motor T2208 KV 1370. Esc 15-20 amp. Prop 7050E or 6050E. So I break that down and get a BL2210/30 motor. 30 amp esc. And the prop says EP 8040. When I launch it there's seems to be not enough power. I can hover it about 5 ft off the ground and it flys about 5 mph at full throttle. How far off am I and is that why this won't fly. Thanks.
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Old Jul 12, 2012, 02:44 PM
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Originally Posted by John S. View Post
I just finished the large pop wing 35. I"m having a problem deciphering the electric motor sizes. It calls for a motor T2208 KV 1370. Esc 15-20 amp. Prop 7050E or 6050E. So I break that down and get a BL2210/30 motor. 30 amp esc. And the prop says EP 8040. When I launch it there's seems to be not enough power. I can hover it about 5 ft off the ground and it flys about 5 mph at full throttle. How far off am I and is that why this won't fly. Thanks.
Are you using a 2 cell or 3 cell battery ? And where the prop says EP 8040 , is that writing facing the front of the plane or the back ? When it flies at 5 mph is the nose up a lot ?
Old Jul 12, 2012, 03:32 PM
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3 cell 850 mah 25-50 discharge rate. The number in the prop is facing away from the plane and yes it's definitely nosing up big time.
Old Jul 12, 2012, 06:35 PM
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3 cell 850 mah 25-50 discharge rate. The number in the prop is facing away from the plane and yes it's definitely nosing up big time.
The numbers/letters on the prop need to face forward or the prop is not working efficiently . And if it's nosing up a lot ( I'm assuming the elevons are trimmed just a couple of degrees above neutral for reflex ) try moving the battery forward until it flies level . If the battery is as far forward as it will go and it STILL flies nose up you might have to get a bigger ( heavier ) battery . It sounds like the motor you put on it is a little bit heavier than the recommended motor , causing the plane to be a little tail heavy .
Last edited by balsa or carbon; Jul 12, 2012 at 06:40 PM.
Old Jul 12, 2012, 08:39 PM
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Did any of that work ?
Old Jul 13, 2012, 04:25 AM
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I'm gonna find out in the next day or two. Thanks for the advice. I think you right about it being tail heavy. The only problem is there is no adjustment for the battery to be moved and the battery fits perfectly into the cut out in the wing. I would have to modify the compartment to change the battery size which means cutting out foam from the front of the wing which would make it even more tail heavy.
Old Jul 13, 2012, 08:04 AM
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You'll be cutting foam out, but will be adding a heavier batt. 1000 to 1300 ma.

Gord.
Old Jul 13, 2012, 01:16 PM
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I'm gonna find out in the next day or two. Thanks for the advice. I think you right about it being tail heavy. The only problem is there is no adjustment for the battery to be moved and the battery fits perfectly into the cut out in the wing. I would have to modify the compartment to change the battery size which means cutting out foam from the front of the wing which would make it even more tail heavy.
You could go with a lighter motor/ESC and save the heavier one for your next plane ( there's ALWAYS a next plane ! ) or add some stick-on lead weights ( from your local hobby shop ) to the nose . That would make the overall weight of the plane heavier , and it will have to fly faster as a result .
Old Jul 13, 2012, 04:05 PM
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my guess is your problem is a combination of pitch speed and battery. Your plane is calling for a 7x5 or 6x5 , but you are using an 8x4 . The first number in the prop is the diameter, the second is the pitch speed, which is how far the prop would travel in one revolution (if you pretend its going through a sold) the 7x5 or 6x5 will travel 5 inches per revolution, while your 8x4 travels 4 inches per revolution. Add to that the increased diameter is going to slow it down a bit too....

Even assuming a 2 cell you should still get a 35mph pitch speed according to what I can see about that motor, unless your battery isnt up to the task, which would slow it down even more.....
Old Jul 13, 2012, 04:54 PM
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You could go with a lighter motor/ESC and save the heavier one for your next plane ( there's ALWAYS a next plane !

There's 25 planes in the hanger now. I have a sickness with buying planes. I'm going to try a larger battery and a smaller prop. If thats no good then Ill go with a smaller motor I guess. I'm also going to turn the original prop I tried around and see if that was it. One way or another I'm getting this thing off the ground and flying.
Old Jul 13, 2012, 10:01 PM
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with 99% of props, you want to make sure the numbers face the front of the plane.
With many props, one side will be rough/matt and the other smooth/shiny, in that case the smooth/shiny side would face the back of the plane.
In ALL cases if one side is "scooped" or concave looking, that side will face the back of the plane.
Old Jul 15, 2012, 10:55 AM
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Update. Turned the prop around so it actually faced the right way and added an 3s 2200 mah battery, much heavier than the previous one, to counter the cg issue and the wing flys very nicely. Its no speed burner but 1/2 throttle on low rates was fine for me. Thanks everyone for the helpful info.
Old Jul 15, 2012, 11:51 AM
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I didn't see anywhere that you said what the KV rating of your motor was. This is also part of the equation. You stated that specs called for 1370 (I believe), and if you put a 1000 KV motor on it, the prop will be turning quite a bit slower than if you had the recommended KV rating. The KV rating is basically rpm's the motor will run x volts. So if you put a lower pitch prop than recommended, then put a lower kv motor you really slow things down.
Old Jul 15, 2012, 01:43 PM
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Update. Turned the prop around so it actually faced the right way and added an 3s 2200 mah battery, much heavier than the previous one, to counter the cg issue and the wing flys very nicely. Its no speed burner but 1/2 throttle on low rates was fine for me. Thanks everyone for the helpful info.
Glad it worked out for you!


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