OutRunner brushless motors?

[microgoat]

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.

 

[JohnRobHolmes]

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!

 

[DirkDigler]

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.

 

[microgoat]

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.

 

[Ronin8451]

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.

Hey ! I resemble that remark ! LOL ! I have an Axi 2820/20 brushless outrunner that I am gonna try in either a PTI Goliath or a TLT-1 . I should be able to get away with using a Mamba 25 since the thing will be geared. I am a dealer for MEC gearboxes for the airplanes and can get 4mm and 5mm wide faced 48 pitch pinions from them to use on it too. This Axi has a Kv of 1,100 and a no load speed of 8,800 rpm's and weighs 161 grams. All of my brushless motors have almost too much braking force in my cars and the outrunners have a high cogging factor from all of the magnets used ( multiple poles- 14 in the Axi ).

Rick

 

[microgoat]

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.

 

[FritoBandito]

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!

 

[microgoat]

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.

 

[JohnRobHolmes]

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!

 

[microgoat]

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.

 

[Krod_Clod]

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.

 

[FritoBandito]

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.

Castle Creations speed controls are the best period. I use nothing but their gear. Their airplane lineup is unmatched but they need more options for cars.

 

[Bsmooth]

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!

 

[JohnRobHolmes]

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.

 

[kaker123]

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.

 

[microgoat]

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?

 

[JohnRobHolmes]

sounds very promising to me!! makes me want to get out the old outrunners and bolt em up!!

 

[microgoat]

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

 

[Bsmooth]

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!

 

[microgoat]

Mamba's lookin' pretty good right now. just gotta get the funds together.