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Old Mar 04, 2005, 09:28 PM
mrX
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Easystar and BP 12

After about 12 or so flights, my stock motor is making its groans. I run it pretty hard on an 8 cell KAN 1050. So am in the market for a motor for it. Thought a cheap brushless might be the trick and came across the BP12:

http://www.clayshobbies.com/Motors%2...lessmotors.htm

If my measurements are right, I could mount that on the Easystar, possibly attaching its motor mount to a piece of pipe that could slide in the existing motor mount. Put the ESC in the pipe and be good to go. With a small groove, could even run an 8" prop (I think).

According to online information I can find, with an 8" prop it would draw 4 less amps at WOT than my current setup, and put out about 4 more ounces of thrust.

My thoughts are that a brushless would be less expensive in the long run than having to replace motors every 15-20 flights. I like the idea of less amp draw and longer flights, the thrust increase isn't that big of a deal, as it flies well as it is.

Anyway, if someone's done this and has some pics, it'd be appreciated.
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Last edited by mrX; Mar 20, 2005 at 10:54 PM.
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Old Mar 04, 2005, 09:30 PM
mrX
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Oh, I guess the other thing I should ask:

Can you turn these types of motors around to face backward and still run them?
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Old Mar 04, 2005, 10:42 PM
mrX
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Laid it out on paper a bit. The current motor turns a 6x3 AP prop without striking the fuselage. So I'd need an additional inch to have clearance for an 8" prop. Drawing the profile, it seems an 8" isn't going to be a problem. 3/4" is already there in the difference b/w where the shaft is. The other 1/4" will likely be made up by the angle of the shaft out from the mount.
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Old Mar 19, 2005, 10:52 PM
mrX
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Got around to picking up a BP12 today. I'm impressed for $27. Got it at http://clayshobbies.com/ a local place (friendly staff btw). This thing is dead quiet.

Anyway, in my pic above, I may have underestimated how it would mount, and could possibly use a 9" prop. I like to think thru things, so haven't mounted anything yet. But I'm thinking of changing the thrust line a bit to more forward than down, which would put me back to an 8".

Now to figure out a mount that doesn't require cutting the foam.
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Old Mar 20, 2005, 05:27 AM
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I see the motor is a brushless. How much did the speed control cost? You can't use a brushed speed control on a brushless motor.
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Old Mar 20, 2005, 06:54 AM
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Super happy with my $69 brushless and controller from Dymond Modelsports. See my post about mounting at
http://www.rcgroups.com/forums/showthread.php?t=342661

RonJ
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Old Mar 20, 2005, 09:56 AM
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I'll be interested in seeing how this goes, Mr X. Supposedly those little CDrom motors work best in quicker, smaller models. However, they are such a deal that folks have put them in all sorts of planes (BP brushless motor/esc thread).

Joe
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Old Mar 20, 2005, 12:44 PM
mrX
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Quote:
Originally Posted by aeajr
I see the motor is a brushless. How much did the speed control cost? You can't use a brushed speed control on a brushless motor.
Got the speed control at the same place for $30 (18A one, dunno name brand). I have a phoenix 25 that I was using on my SS brushless project. So didn't really need this one, but the price seemed right.

Got some 8x4.3 GWS black props. They sure are flimsy. Doesn't seem to put out much. Might have to try to get ahold of some APC varieties for this.
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Old Mar 20, 2005, 01:02 PM
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Thrust rating on that motor is only about 10 ounces, if I read the mfg specs right. Similar to a speed 400 brushed motor.
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Old Mar 20, 2005, 10:39 PM
mrX
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Got it mounted. That's an 8x4.3 prop shown in the pic. Gonna pic up some different pitch 8" props tomorrow. Sometime this week I'll get a flight report.

I was thinking that the stock motor was giving me about 12 oz. of thrust on the 6x3 prop. The chart on this motor shows pretty good numbers.

Quote:
Configuration: Propeller: Volts: Amps: Thrust:
Direct Drive 8040 7.4V 5.4A 10.0 oz / 286 grams
Direct Drive 8040 8.4V 7.2A 13.1 oz / 374 grams
Direct Drive 8040 9.6V 8.5A 16.3 oz / 466 grams
Direct Drive 8040 11.1V 9.6A 19.6 oz / 560 grams
Direct Drive 8043 7.4V 6.1A 11.1 oz / 317 grams
Direct Drive 8043 8.4V 7.0A 12.9 oz / 369 grams
Direct Drive 8043 9.6V 8.8A 16.6 oz / 474 grams
Direct Drive 8043 11.1V 10.3A 20.6 oz / 589 grams
So, 16 oz.+ of thrust with the batteries I have. We'll see tho.
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Old Mar 20, 2005, 10:51 PM
mrX
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Btw, made some measurements on the BP12. The bell is 30mm OD. The magnets are 4x2x10mm. The stator is the 12 pole variety (25mm'ish). There are 14 magnets around the bell.

For whatever reason, it is no longer "dead quiet". Don't think I changed anything. Sounds like my Himax 2012-850 now, which isn't loud, but does make a noise.
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Old Mar 20, 2005, 11:16 PM
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I think I'd take some chunks of foam and glue them back to the board, shape them to be more aerodynamic, blending in with the fuse, and probably covering the ESC on the back with a rounded cover of some sort... providing for cooling as well. I have no idea what the net gain of the thrust to drag ratio is, but that looks like a large speed brake to me... Just my $0.01. It does look cool to be able to swing that 8" prop though!
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Old Mar 21, 2005, 01:06 PM
mrX
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Got to fly it today at lunch. Found a more reliable way of measuring AUW, and found out my Easystar is right at 25.0 ounces with this motor.

I changed to an 8x6 APC prop. Using the 8 cell KAN 1050s, I throttled up and threw it. I'd guess it climbed about 2-3 times as fast as stock. It got to altitude pretty quick. There was none of the trying-to-climb-too-fast stalls. As far as speed, it might have been a bit faster, but nothing to write home about. The difference I noticed was when flying into the wind. It was about 5 mph winds, with some gusts, and it would power right into it with less throttle. Flew very nicely at 2 clicks below half throttle.

Don't really know how long the battery would last. Was out there for 1/2 hour and never changed the battery. That's without pushing it very hard. And gliding down for 4 landings. Never hit the LVC by the time I put it in the car. Battery is measuring 10.27 volts as I sit here, if that means anything.

Wasn't all peachy tho. I've never had trouble landing this thing until today. Seemed it would get 10 feet or so off the ground on approach, and then it was anyone's guess what it would do. Mostly the left wing dropped and it would pinwheel. Dunno if this is something to do with the "speed brake" or not. Gonna build that up to make it more aerodynamic.
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Old Mar 21, 2005, 02:27 PM
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Quote:
Originally Posted by mrX
Dunno if this is something to do with the "speed brake" or not.
Very cool, congrats on the success! With the off axis drag of mount and prop you may have increased the stall speed. Streamlining should help as would a folding prop. In the meantime try bringing it in a little hotter (not just floating it in like the stock version will do) until you are just off the grass.

Joe
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Old Mar 21, 2005, 06:15 PM
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Your CG may be off a little bit. Did you rebalance the plane after all the changes?
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