06-21-2005, 11:13 AM | #1 |
I wanna be Dave Join Date: Feb 2005 Location: Cleveland, OH
Posts: 8,009
| OutRunner brushless motors?
i've seen some of these little OutRunner brushless motors the airplane guys use, about as big around as a half-dollar and maybe 3/4 inch thick. supposed to be as powerful as a brushed 600. the cool thing about em, they turn super slow, like 1000 rpm/volt, and the ESCs have 3A BECs. that'd be the t!ts for weight reduction, but how are they on torque? has anyone tried one yet? or do i have to be the first? just think, lose the heavy 540 motor, the big speedo and the sub-C's, run one of these with a 2/3A pack, you'd chop half a pound or better off your rig. i'll see if i can borrow one from one of me airplane buddies. this could be good. |
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06-21-2005, 11:45 AM | #2 |
owner, Holmes Hobbies LLC Join Date: Nov 2004 Location: Volt up! Gear down!
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do it! do it! i have yet to try brushless. i have wanted to try one in a crawler since before i had one. i think a high speed outrunner geared low would be the ticket. give one of your buddies motors a shot. i would love to hear how it goes! i think my tlt would be the first to get a brushless. the more powerful motors needed for bigger rigs would crush most drivetrains. i wouldnt want to wedge a tire and then have my lehner xl5000 cog a few times. da da da snap! |
06-21-2005, 12:26 PM | #3 |
I wanna be Dave Join Date: Jan 2004
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Just remember that there is little cogging associated with brushless. The motors spin very freely. This reduces the "engine breaking" affect. So, when you crawler is traversing downhill, it will roll pretty quickly without you tapping reverse.
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06-21-2005, 12:35 PM | #4 |
I wanna be Dave Join Date: Feb 2005 Location: Cleveland, OH
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the outrunners cog almost as much as a brushed motor, and the brake on a BL ESC is very efficient. so i'll try it. trouble is, there's never an airplane weenie around when you need one. |
06-21-2005, 01:03 PM | #5 | |
Newbie Join Date: Jun 2005 Location: Weatherford
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06-21-2005, 02:43 PM | #6 |
I wanna be Dave Join Date: Feb 2005 Location: Cleveland, OH
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i've got a loaner lined up for Thursday. then we'll see if this thing will, er, fly, or not. another idea would be to gut a 540, just use the can and endbell, slide that heli main gear (the one from "oh the possibilities") into it with a pinion on the other end, and use a small Mamba-type BL to drive that big gear. too many ideas and not enough money. Last edited by microgoat; 06-21-2005 at 02:46 PM. Reason: more ideas |
06-21-2005, 03:09 PM | #7 |
Pebble Pounder Join Date: Apr 2005 Location: Torrance, CA
Posts: 177
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Considering the low speeds and high run times we're already getting, I don't really see any advantage to running a brushless motor. Maybe longevity of the motor itself but that's it. Not to say I have anything against brushless motors. In fact I have a pile of them (including outrunners) in my planes and cars. The only thing I use a brushed motor for is crawling. I just don't see any motors that fit our application as well as the Integy lathe motor does. Of course it's always fun to try new stuff so go for it! |
06-21-2005, 03:30 PM | #8 |
I wanna be Dave Join Date: Feb 2005 Location: Cleveland, OH
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the major advantage i'm thinking of is weight reduction and lower cog. dropping the Titan in favor of a small outrunner will shave 6-7 ounces off the top of the rig. losing the EVX for a little circuit board will drop another couple ounces, and swapping the sub-Cs for 2/3A cells will save even more weight. and all the weight saved is in the chassis, 3-4 inches off the ground. that's gotta help. we'll find out on Thusday. |
06-21-2005, 05:24 PM | #9 |
owner, Holmes Hobbies LLC Join Date: Nov 2004 Location: Volt up! Gear down!
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i cant wait to hear how it goes! which esc are you gonna use, the mamba 25? make sure your firmware (software?) is up to date, and keep a really close eye on the temp!
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06-21-2005, 07:23 PM | #10 |
I wanna be Dave Join Date: Feb 2005 Location: Cleveland, OH
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the esc for testing will be whatever is attached to the motor i'm borrowing. probably a Phoenix-25. i know, no reverse and probably not set up for braking, as it came off a recently-crashed airplane. once i know whether or not it will move the truck, i'll probably use a Mamba esc, as 25 amps should be more than enough. that way i can have brakes and reverse. tomorrow i'm hooking up a bud's Whatt Meter to it, to see how much juice it takes to move this pig as-is. then i'll know for sure about current requirements. |
06-21-2005, 07:44 PM | #11 |
Pebble Pounder Join Date: Feb 2004 Location: Pittsburgh PA
Posts: 127
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the phoenix can be programmed to have brake as well as a "soft start". I use a PHx-10 in my heli. VERY reliable little unit, and CC has the BEST support around.
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06-21-2005, 07:52 PM | #12 | |
Pebble Pounder Join Date: Apr 2005 Location: Torrance, CA
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06-21-2005, 08:34 PM | #13 |
Quarry Creeper Join Date: Mar 2004 Location: 18" from computer screen
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What is nice about the out runners is that the have much more torque than the standard can style so when driving a prop, no gearbox is needed. Get a higher voltage motor and run it on half the voltage rating to keep speeds low and the torque reasonable. Also with the mamba controller, you can run lithium cells to further reduce weight!
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06-21-2005, 08:49 PM | #14 |
owner, Holmes Hobbies LLC Join Date: Nov 2004 Location: Volt up! Gear down!
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the start up programming is totally different for the airplane and car ecs's. i wouldnt doubt if it coggs like a mother and doesnt want to start reliably. again, watch your heat on the esc and motor- this motor is gonna be stalling a lot. if it doesnt work try a mamba before calling it done. |
06-21-2005, 09:25 PM | #15 |
Newbie Join Date: Jan 2005 Location: cabot
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just from my expe3rience with airplanes and helicopters with brushless motors, i would suggest at least a 10a speedo for a crawler, i have burnt up a couple of the 3s's in my helo, just a suggestion.
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06-23-2005, 04:39 PM | #16 |
I wanna be Dave Join Date: Feb 2005 Location: Cleveland, OH
Posts: 8,009
| un-fawkin'-believable
i bolted up the AXI outrunner and took it for a test spin. first i discovered my XR3i doesn't speak airplane language, so i couldn't change the settings on the ESC, and had to reverse the throttle in order for anything to work at all. this of course will be remedied with a car ESC if i go ahead with the project. the settings i had were, 4.0 cutoff voltage (which never cut in), very sensitive current limiting, which shut down the motor in stall situations to avoid blowing my borrowed ESC (not a bad thing considering), soft, delayed brake (still very effective), auto calibrating throttle (whatever that is, it was still backwards), high advance timing for more power, less efficiency, hard cutoff at low voltage or over-current, and very soft start (for use with fragile gearboxes, which the E-Maxx box ain't). less than ideal settings, but with no way to change them, i set out anyway. first test, extended grass bash: tooling along in second gear over the grass and weeds, no problems whatsoever. motor barely warm, ESC a little warmer. grade: A second test: climbing plywood. this was an attempt to stall the motor so i left it in second. plywood at a 45 degree angle. the "very soft start" hampered me here. starting on level ground, it would go right up, never slowing down. starting on an incline, the motor would struggle til it got a couple revs in, then went right up. in first gear, no problem. right on up. motor a little warm but not oncomfortable to touch, esc a bit hotter. grade: B+ (allowing for soft start troubles) third test: actual rocks. again hampered by the soft start, but if the truck slid backwards and got the wheels turning, the motor kicked in and blasted away. lack of reverse and a backwards throttle didn't help, and the body was off so i could check temps, so this wasn't a great crawl. however, the motor did well, except for stalling due to the damned soft start. motor warm but not hot, esc kinda hot. grade: B fourth test: flat out torture. hold the truck down and give it throttle. the diff chattered before the motor stalled so i will have to say grade A speed was similar to the EVX/Titan combo. a bit faster than walking in 2nd gear, slow as hell in first. since all the issues i had were with the programming, and not the motor, i think i will go ahead with this, using a Mamba-25 ESC and a similar motor to the one tested. i was flat-out stunned at how well this dinky-azz motor performed. i'm looking forward to doing the upgrade permanently. anyone want to buy a modded EVX and a Titan? |
06-23-2005, 05:04 PM | #17 |
owner, Holmes Hobbies LLC Join Date: Nov 2004 Location: Volt up! Gear down!
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sounds very promising to me!! makes me want to get out the old outrunners and bolt em up!!
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06-23-2005, 05:15 PM | #18 |
I wanna be Dave Join Date: Feb 2005 Location: Cleveland, OH
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motor specs: AXI model 2212-26. 7.1 amps max draw on 6 cells, 4950 max rpm. no specs given on torque. runtime was a little under an hour. there's still a bit of juice left in the battery. http://www.hobby-lobby.com/brushless-axi2212.htm Last edited by microgoat; 06-23-2005 at 05:19 PM. Reason: more info |
06-23-2005, 05:40 PM | #19 |
Quarry Creeper Join Date: Mar 2004 Location: 18" from computer screen
Posts: 213
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so what ESC are you gonna run? The mamba esc? it is 25 amp rated and has reverse. Also a programable voltage cutoff to run lipolies!
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06-23-2005, 05:51 PM | #20 |
I wanna be Dave Join Date: Feb 2005 Location: Cleveland, OH
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Mamba's lookin' pretty good right now. just gotta get the funds together.
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