lotaloi

Guys,
I don't understand why most 1/18 or 1/10 sizes use inrunner type motor which is horriblly expensive. Why not outrunner? They are more powerful;I think cheaper than inrunner cr*p.[:@] I preffer outrunner as I can fix it,and it's more simple. What u say?

iTz Nicholas

Aren't most outrunner motor open so dirt can easily get inside the motor?

Access

A lot of RC is still based around racing and outrunners are illegal in just about every class. I saw an outrunner once in a rock crawler but that's the only time I've actually seen one in a ground RC. There has been a few threads where people were putting powerful outrunners in monster trucks but that's about it.

lancer123

becasue things get easily into the motor and scratch up the copper wires which shorts the mtor and makes the motor smoke .

it even happened to my ili bros inrunner with the slighest grain on sand

sonicj

My Feedback: (2)

i ran a 3900kv outrunner in my pro-pulse for a few weeks. loads of torque and ran really cool. its wan't nearly as "harsh" as my 20mm inrunner mamba motors. very smooth. as far as dirt, its gonna get in there, but most are easily serviceable. the one i was using opened after removing a single e-clip. bearings are easily replaceable. gotta keep wires / fingers out of it!

flipside7

The medusa in runners claim to be more powerful and efficient than out or inrunners on the market. Just a claim, any feedback??

Access

Same here, when I was talking with Patrick once he mentioned that Steve Neu 'did not believe' in outrunners b'cos of the efficiency problems inherent in the design. It's possible to design a very efficient inrunner (your coils are far apart and your permanent magnets are in the middle) but the outrunner the opposite applies and the coils are closer together, they will tend to bleed magnetic flux more than the inrunner design. With aircraft the outrunner was a big efficiency saver simply b'cos it allowed a direct drive setup. With ground RC there really hasn't been much innovation there. Direct drive has its own downsides, like the inability to adjust gearing.

studysession

An out runner came in my RC18 clone. I got it from Model-Fun RC. Unsure of exact brand of motor - it has a model fun sticker on it. Not sure if they make the motor or just sell them. Got the RC18 clone for real cheap off EBay as a RTR. Came with the brushless setup.

That is first RTR I've seen that came with an out runner brushless.

dacaur

Outrunners are good in planes because they have lots of tourqe. Outrunners are natrualy lower kv in the first place, plus a 2000Kv outrunner has more tourqe than a 2000kv inrunner, and , This is great for plane because you can eliminate the gearbox and still use a big prop. They are also cheap. The downside is, as mentioned, the open design, which isn't a problem in a plane since they way up in the sky. RC cars would have issues though. Also RC cars dont need the tourqe advantage, since you cant eleiminate the gearboxes anyway.

Access

dacaur you could eliminate the gearbox with an outrunner it would just require a radically different design. You'd need something like a motor-axle-wheel drive with the motors bolted to the chassis and the axle dropping down to the wheel. One motor for each drive wheel. Instead of steering by turning the wheels, the motors (preferably sensored) would vary their speeds to make the vehicle turn. Think of a 'virtual differential'. It serves the same purpose as a normal differential, only it varies based on user input (steering).

The same idea with brushless where you went from a mechanical switch in the motor to an electronic switch based on a sensor input coming from the motor. Now you are replacing a mechanical differential with an electronic one based on steering input, possibly also combined with traction control.

Aimlessone

You can take the gearbox-less format even further by having in-wheel motors. Take an outrunner, attach the stator to the suspension arm and the rotor to the wheels. The only moving parts in such a drivetrain would be the wheels, but the increase in unsprung weight might be an issue along with the sheer electronic complexity of it.

dacaur

wow, that would be cool!

sonicj

My Feedback: (2)

imagine the reliability and ease of maintenance of such a setup! 95% of my surface rc downtime is due to drivetrain issues. replacing every bit of the drivetrain with 4 easy to maintain / troubleshoot motors would be godsend!

i don't think it would be as complex as it might seem to contrive such a system... a external convertor similar to a tail mixer for aircraft and the rest could be off the shelf components. im no whizz on the dx7, so idk for sure, but it has a LOT of mixing options onboard and i wouldn't be surprised if its capable of controlling such a critter out of the box!

chilidillo

If you guys could build such a beast, you'd be rich and famous; I sure would buy one just because it's so unique!

dacaur

You wouldnt even need to do any complex mixing, just use a normal steering setup....

Access

I actually did try something like this a few years ago. I built a 3-wheeler with two wheels in front (used for steering) and a single rear drive wheel. The drive wheel was basically a drilled out touring car wheel on a prop mount, with the outrunner right there. No suspension or anything like that since it was just a mockup. Having a single drive wheel you didn't really need any kind of mixing or sync between multiple motors.

What I did find is that a sensored outrunner is a must, sensorless just isn't going to cut it. So I pretty much left it at that. I don't think a sensored outrunner exists, maybe you can canibalize a sensored motor or something like that...

If I ever make a high-speed tracked vehicle I might use this concept. But again, sensored would be the best way, with a custom ESC that controlled both motors to keep them in perfect sync.