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Old Aug 13, 2009, 08:29 AM
mt_100 is online now
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Another Maiden Flight - Good but just off


Seems my motor selections are off lately, little on the small side so I need the opinions of an expert, or group of them

The plane is a House of Balsa Laser Stick 10 (Chea Pass) and is flying with a KDA 22-20L from Hobby City with a 9x5 prop and 3S 2200 pack.

Takes off out of grass in about 25' and flies wonderfully. Club trainer even liked how stable it was compared to a 40 trainer. It flies so well I almost don't want to ruin it. Honestly took my hands off the Tx for a minute while it went one side of the field to the other in a 10mph wind and watched it stay straight and level.

It's a smidgen slow and cruise is at 3/4 throttle and that doesn't leave a lot of extra for fun. I have the ability to go bigger and would like to but don't want to break the bank.

So considering the prop is about maxed when it comes to ground clearance on takeoff should I try a 9x7.5 prop and see if that kicks things up a bit or just put the motor somewhere better suited and look for something a little bigger?

I have this motor on the shelves http://www.headsuprc.com/servlet/the...lectric/Detail but also think it may be a smidge small for the plane.

Thoughts and opinions?
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Old Aug 13, 2009, 12:27 PM
whitecrest is offline
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For the House of Balsa Laser Stick 10:
Wingspan 45.5"
Wing area 318 sq. in.
AUW 30 oz.

For excellent performance, you are probably looking for a 1200 Kv outrunner that can handle about 28 amps of continuous current while swinging a 9x6 on your 3S 2200 mAh lipos. Your batteries could easily provide this current level which is just a bit more than a 10C draw. Your motor should weigh around 3 oz. I have attached a WeboCalc projection using the data listed for your ship.

I would say that the motor you are considering as a replacement is in the ballpark, but would agree that it may be a bit small for the level of performance you are looking for. You need just a bit more Kv for extra pitch speed and a little more power-handling capability.

P.S. I am definitely not an expert but think Flieslikeabeagle (author of Webocalc) is. Thanks for providing the example. It's a lot of fun running numbers on WeboCalc. Good luck with your new setup!
Last edited by whitecrest; Aug 13, 2009 at 01:00 PM.
Old Aug 13, 2009, 12:50 PM
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Yup, I agree. 1200 Kv would be about right. A Suppo A2814-08, Dualsky XM3530CA-12T, Electrifly Rimfire 28-30-1250, and plenty more would fill the bill.
Old Aug 13, 2009, 01:08 PM
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You didn't mention your current draw. If you're within the current specs, just try the 9 x 7.5, it's a cheap $3 upgrade and the pitch speed will increase significantly compared to the 9 x 5. If that doesn't do what you want then upgrade the motor.

Azarr
Old Aug 13, 2009, 01:14 PM
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I may play with the gear too. Moving it forward 1/2" will give me a lot more prop clearance and a bigger prop.

Current amp draw is around 14 amps at peak on a 3S 2200 so it is well within it's capability.
Old Aug 13, 2009, 01:20 PM
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I was thinking in the 1200 - 1400 kv range so that sounds about right. Where is a good place to pick up the Suppo motors in the US that is reasonably priced?

Hate waiting two weeks for stuff from China.
Old Aug 13, 2009, 01:25 PM
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What about slapping a 3 blade prop on it like a GWS 9x5 or 10x6?

Anyone think that would produce better results?
Old Aug 13, 2009, 01:50 PM
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LightFlightRC carries them, I don't know how the pricing compares:

http://www.lightflightrc.com/

They have one of those silly frames web pages that does not let you copy off links to individual frames of info so you'll have to pick your way to the motor pages.

Jack
Old Aug 13, 2009, 01:50 PM
Ken Myers is offline
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Quote:
Originally Posted by mt_100
Where is a good place to pick up the Suppo motors in the US that is reasonably priced?

Hate waiting two weeks for stuff from China.
Select Products and Motors & ESC, then scroll down the page aways
http://www.lightflightrc.com/
Old Aug 13, 2009, 01:56 PM
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Quote:
Originally Posted by mt_100
I was thinking in the 1200 - 1400 kv range so that sounds about right. Where is a good place to pick up the Suppo motors in the US that is reasonably priced?

Hate waiting two weeks for stuff from China.
Try Light Flight RC They also provide excellent motor data. There are probably others.
Old Aug 13, 2009, 02:00 PM
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I think I will take Azarr's advice and tinker with the prop a little. It is just to darn nice flying to remotor it right now.

Thinking of picking up a few 3 blade props too.
Old Aug 13, 2009, 02:21 PM
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Quote:
Originally Posted by mt_100
I was thinking in the 1200 - 1400 kv range so that sounds about right. Where is a good place to pick up the Suppo motors in the US that is reasonably priced?

Hate waiting two weeks for stuff from China.
Here are 3 good retailers I have bought from.

http://www.lightflightrc.com/
http://www.headsuprc.com/servlet/StoreFront
http://www.bphobbies.com/view.asp?id=V815101

Wow, 3 people beat me to it with Lightflight RC!!
Old Aug 13, 2009, 02:47 PM
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Quote:
Originally Posted by mt_100
I think I will take Azarr's advice and tinker with the prop a little. It is just to darn nice flying to remotor it right now.

Thinking of picking up a few 3 blade props too.
If you can lengthen the landing gear to accommodate a larger prop, a 10x7 using your present 1000 Kv motor on 21 amps should provide excellent performance. The revised projection is attached below.
Old Aug 13, 2009, 04:33 PM
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I use the GWS 10x6HD prop on all my A20-20L motors.

If you need more power, my suggestion is the SUPPO 2814-8 with a GWS10x6HD or GWS11x7HD for outrageous performance. Max draw will be up to 28A with the 11x7.

2 Sources for the Suppo's - LightflightRC and slickzero. These motors are also sold under the Welgard name and probably others.
http://www.slickzero.com/index.html
and you already have LFRC
http://www.graysonhobby.com/catalog/...php?cPath=9_36

I like LFRC but they are out I see.

Point of reference. My 24oz biplane without battery will take off in about 10' or less with the Suppo 2814-8 and a 11x7GWSHD prop and has unlimited vertical with a well worn old 3s2500 polyquest pack.
Last edited by hoppy; Aug 13, 2009 at 04:40 PM.
Old Aug 15, 2009, 11:01 PM
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Quote:
Originally Posted by hoppy
I use the GWS 10x6HD prop on all my A20-20L motors.

BINGO! Think I may have found the issue. I replaced the landing gear with some new gear for more ground clearance and checked the prop. Turns out I had a 9x5 on it!

Put a 10x6 on, and checked amp draw and it is 18.5 static so very nice.

Plane weighs 30.5 ready to fly so I think it will be a great sport model.

I'll report back as soon as I can get out to fly.


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