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Old Feb 24, 2015, 09:31 PM
like freakin' NASA in there.
Jmel's Avatar
United States, NC, Winterville
Joined Jul 2014
220 Posts
I agree on the grass field part. I use a GPS Logger. Bought off eBay for 30 - works well enough. Miller convinced me on the Waco motor and prop. His flies great with it. I've not installed yet, it's all ready to go after I do a speed reading on the original stock setup. Then I'm going to do another after the install.
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Old Feb 24, 2015, 10:51 PM
Yes it was Abby Normal
Joined May 2012
2,601 Posts
Quote:
Originally Posted by Jmel View Post
I agree on the grass field part. I use a GPS Logger. Bought off eBay for 30 - works well enough. Miller convinced me on the Waco motor and prop. His flies great with it. I've not installed yet, it's all ready to go after I do a speed reading on the original stock setup. Then I'm going to do another after the install.
Aye very good Jmel....so we may have a first here with some good data comparisons. Very interested in your results both on 4s power.

So you are hopping up to the Kv650 motor and the XOAR 13x6.5 prop?

I need to look into a GPS logger for myself and see what the stock Kv900 motor is delivering!!

TwistedGrin
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Old Feb 25, 2015, 09:55 AM
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gooniac33's Avatar
Sunnyvale
Joined Feb 2009
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Lower kv and larger prop would do this plane some good. So I am sure that the Waco set up would work pretty good. There are some rocket motors that I am tempted to try out that would drop right into this plane. If I had decided to get nutty with it then that is the route that I would go! However I am loving it as it is now! I don't see a need to change it! Especially when there are 4 or 5 flying together like it usually is at my field. It is cool to see us all thottle up and stay there with eachother in a big pack instead of one or 2 shooting off into the distance. It makes it more competitive and fun!
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Old Feb 25, 2015, 11:45 AM
like freakin' NASA in there.
Jmel's Avatar
United States, NC, Winterville
Joined Jul 2014
220 Posts
Yeah I am having to put the waco motor and 13x6.5 prop in to keep up with Miller

I flew same as he did the other day with him, and I was at full throttle the whole time. He landed at 3.8v or so, I was way past danger zone at 2.8! This was with mine completely stock and his with Waco and 13x6.5
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Old Feb 25, 2015, 01:49 PM
Must not buy more planes!
mclarkson's Avatar
USA, KS, Wichita
Joined Jul 2010
2,494 Posts
Alright, first I want to be clear that I'm not arguing with anyone, or denying Miller's results, because I haven't tried them. But ...

I just don't see how it's possible that the plane is faster on a 650kV motor with a 6.5" pitch than on a 900kV motor with a 6" pitch. The math says it should be about 20% slower. I know that's not the whole story but still ...

What's going on here?
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Old Feb 25, 2015, 02:03 PM
teaching to learn
millerr74's Avatar
United States, NC, Greenville
Joined Oct 2013
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Mclarkson, my hypothesis is that due to the waco motor being a bigger can, it has more power and thus spins the prop at full capacity. The stock 900kv motor is a smaller can and most likely doesn't actually turn the prop at the rated rpms. So the math as you calculated it would indicate that the 900kv would spin the prop faster than the 650kv motor, but the real world application seems to result in an actual faster prop with the lower kv because it has more power and therefore is more efficient / effective at spinning the prop.
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Old Feb 25, 2015, 02:05 PM
Must not buy more planes!
mclarkson's Avatar
USA, KS, Wichita
Joined Jul 2010
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Alright. As I said, I wasn't doubting you. The results just seemed .... odd.
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Old Feb 25, 2015, 02:10 PM
teaching to learn
millerr74's Avatar
United States, NC, Greenville
Joined Oct 2013
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Originally Posted by mclarkson View Post
Alright. As I said, I wasn't doubting you. The results just seemed .... odd.
Yes, we're investigating a mystery here. Does my proposed explanation make sense in this application?
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Old Feb 25, 2015, 03:04 PM
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gooniac33's Avatar
Sunnyvale
Joined Feb 2009
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Originally Posted by millerr74 View Post
Mclarkson, my hypothesis is that due to the waco motor being a bigger can, it has more power and thus spins the prop at full capacity. The stock 900kv motor is a smaller can and most likely doesn't actually turn the prop at the rated rpms. So the math as you calculated it would indicate that the 900kv would spin the prop faster than the 650kv motor, but the real world application seems to result in an actual faster prop with the lower kv because it has more power and therefore is more efficient / effective at spinning the prop.
It makes sense but also makes me think that a higher pitch prop may actually work better on that motor. I was actually thinking of getting a motor that will spin a 12x12 on 3s....
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Old Feb 25, 2015, 03:44 PM
teaching to learn
millerr74's Avatar
United States, NC, Greenville
Joined Oct 2013
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Wow! 12x12 sure would be a sight to see before the whole power plant explodes into a pyrotechnic masterpiece . Make sure you get it on video goon.

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Old Feb 25, 2015, 04:05 PM
like freakin' NASA in there.
Jmel's Avatar
United States, NC, Winterville
Joined Jul 2014
220 Posts
I think there should be a little room to grow in the 12 inch prop arena, since the 6 pitch is only chomping at 27a. Isn't the stock ESC a 40a?

Also, I went with lucky 13, since Miller had lucky 7.

Einstein is quite comfortable in the pilot seat.

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Old Feb 26, 2015, 01:11 PM
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Sunnyvale
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Originally Posted by millerr74 View Post
Wow! 12x12 sure would be a sight to see before the whole power plant explodes into a pyrotechnic masterpiece . Make sure you get it on video goon.

There are quite a few motors capable of doing that. But I need to see if they will work on this model. I had that set up on a Parkzone Trojan back in the days. on 3s it was a beast and on 4s insane!!! the rate of climb was like a hotliner! I wouldn't run 4s on the Gee Bee with that set up but 3s would be perfect.
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Old Feb 26, 2015, 01:38 PM
teaching to learn
millerr74's Avatar
United States, NC, Greenville
Joined Oct 2013
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I got you on that gooniac. I missed the part you said about using a different motor with your 12x12. I thought that you were going to just pop it on the stock motor and have at it.
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