My First E-Dune Runner

[Deluge]

Figure you could take the one from your old dryer... but Im not sure how you would keep the extension cord plugged in ha ha ha

Lmao! Yeah, that would be a problem.

 

[mulepic]

I remember that build! He's a member here, too. Pretty awesome setup.

Maybe he'll come on and give some advice and/or sell me his motor. I noticed how my gearbox is much beefier than what he had several years ago. Redcat did a nice job beefing this thing up.

45.. Too fast!? No way, unless you plan on just running really tight tracks. 35 is about stock speed for the gasser you just yanked out.

There's a big difference in gearing between 35 and 45 i.e. 10:1 vs. 13.1:1, that 30% equates to much cooler components and significantly longer run times. To to be honest, the track I was at didn't require pushing 45 mph. Being conservative on gearing is much easier to work with then starting out of the gate over geared.

As much as I want to see this thing be lightening fast, I won't be too happy having to send my esc/motor back b/c I calculated wrong.

I'm still trying to solve this one and as I get more concerned about how to mate up the motor to the gears I keep thinking about a dual motor set up.

 

[mulepic]

I have been reading about e-bikes and the motors and controllers to run them: [ame]

[/ame]Interestingly enough some (not the above video) were talking about using RC motors and controllers for a rear wheel friction type set up. They'd use an outrunner a spinning drum up against the rear wheel to power it. Here is a motor that was mentioned: http://www.leaderhobby.com/product.asp?ID=9394001224730#4

The difference with e-bikes is there power profile is opposite of ours. They use very high voltage and low amps to keep everything cool. Since I'm running such a low (mechanically high) FDR this is something to look into. The issue w/ using HV ESC's meant for boats and planes is that they don't deal w/ the startup or brake current RC's need to tear around the track. At least we have the brake part figured out by using mechanical brakes. The startup is the other challenge.

Here is what I'm thinking so far. If I use an outrunner (well protected from the dirt) I can attach the stock pinion to one side of it and a startup gear to the other. The startup gear will have a one way bearing on it. This startup gear will be powered by a sensored 1/8-sized brushless motor w/ a very low gearing. This sensored motor will get the larger outrunner moving to prevent the large startup current needed to overcome the inertia.

Here is an image I found that sort of gets what I'm thinking about. You can see how the outrunner has a shaft the extends out both ends.



I just found this video of a guy using an outrunner on his e-bike. He's not using the friction setup but rather a clutch engagement which allows the motor to spin up first before engagement. This too prevents the startup current issue.

 

[Guest]

There's a big difference in gearing between 35 and 45 i.e. 10:1 vs. 13.1:1, that 30% equates to much cooler components and significantly longer run times. To to be honest, the track I was at didn't require pushing 45 mph. Being conservative on gearing is much easier to work with then starting out of the gate over geared.

If your building it for the track the run times are more important than top speed.

 

[Guest]

Those e-bikes are pretty cool.

 

[Guest]

As much as I want to see this thing be lightening fast, I won't be too happy having to send my esc/motor back b/c I calculated wrong.

You could always just change gearing to do some speed runs.

 

[mulepic]

You could always just change gearing to do some speed runs.

Very true.

The more I look into the clutch approach as shown in the pusher bike video the more I like it. It should act just like a gas motor but w/ much better low end acceleration b/c I could imagine the brushless motor spinning up faster than the gas engine but I'm just speculating based off of what I see in videos.

 

[mulepic]

Here is a good example of how a clutch works w/ an outrunner. This also exemplifies why the the startup current is such an issue:

[ame]

[/ame]

 

[mulepic]

Here's is roughly the motor I'm considering. I needs to handle 12s and be around 400kv. I'll run it on 10s though. I just wish I could find something comparable in the US for faster shipping and/or a store I've purchased from before. Does anyone have any experience w/ leaderhobby.com?

https://www.leaderhobby.com/product.asp?ID=9394001226071&Location=HK

A question about selling the gas engine. Can I keep the clutch when I sell it? I'm thinking that clutch and bell housing is specific to redcat, right?

 

[Guest]

Very true.The more I look into the clutch approach as shown in the pusher bike video the more I like it. It should act just like a gas motor but w/ much better low end acceleration b/c I could imagine the brushless motor spinning up faster than the gas engine but I'm just speculating based off of what I see in videos.

You are correct on the acceleration. An electric motor has the same power output through the rpm range. The gas engine increases power output as you get close to the top of the rpm range. The torque is amazing on electric.

 

[Guest]

A question about selling the gas engine. Can I keep the clutch when I sell it? I'm thinking that clutch and bell housing is specific to redcat, right?

Most engines don't come with the clutch bell. It is a Redcat specific part.

 

[mulepic]

Most engines don't come with the clutch bell. It is a Redcat specific part.

Thanks. Can I keep the clutch i.e. the shoes and the thing they mount to? So the only thing sticking out of the engine is the crankshaft. I guess I'll have to take a picture of it.

The reason being is b/c it's looking promising to simply mount the clutch assembly to the electric motor. And leave the pinion mounted to the clutch bell.

 

[Guest]

The clutch shoes and shoe mount are not Redcat specific. They are inexpensive parts so you could sell it with or without.

 

[mulepic]

I found a usa warehouse for leaderhobby and purchased a motor that isn't exactly what I wanted but for half the price and shipped from LA, it'll get the ball rolling on the design.

This one is only 270kv vs. 400kv and is 54mm long vs 61mm. I can run this off of an esc I have w/ 6s just to test and get to speeds of 15mph. Very slow but should test the design. If all works then I'll get an HV esc and hook it up to 10s which will get me to 25mph. If that holds up then I'll get the 400kv motor and hit 35mph.

Here is the motor that should ship soon: https://www.leaderhobby.com/product.asp?ID=9394001224340&Location=LA

While that is shipping we can talk about how to mount the clutch assembly to an 10mm motor shaft.

 

[mulepic]

I just took some measurements to see how the motor will mount in the buggy. I should have done that before I pressed the 'buy now' button. I turns out the motor might interfere w/ the rear driveshaft. There's maybe .005" overlap. I can probably mill a small groove in the motor can circumference to make it fit.

Of course I won't know till it's all together. That's just the way these things go.

 

[Deluge]

Here's is roughly the motor I'm considering. I needs to handle 12s and be around 400kv. I'll run it on 10s though. I just wish I could find something comparable in the US for faster shipping and/or a store I've purchased from before. Does anyone have any experience w/ leaderhobby.com?https://www.leaderhobby.com/product.asp?ID=9394001226071&Location=HK

A question about selling the gas engine. Can I keep the clutch when I sell it? I'm thinking that clutch and bell housing is specific to redcat, right?

You can keep the clutch. The clutch bell is specific to Redcat.

 

[Deluge]

Thanks. Can I keep the clutch i.e. the shoes and the thing they mount to? So the only thing sticking out of the engine is the crankshaft. I guess I'll have to take a picture of it.The reason being is b/c it's looking promising to simply mount the clutch assembly to the electric motor. And leave the pinion mounted to the clutch bell.

You can keep the clutch plate, as well.

 

[Guest]

I look forward to seeing a motor mounted.

 

[mulepic]

Me too. I'm thinking I might be able to rotate the rear driveshaft down by .050" at the center spool to give me .025" breathing room between the shaft and motor.

But before that I'm figuring out what to do w/ the clutch plate. It normally sits on a tapered shaft that goes from .390-.465". The clutch plate screws into the shaft. I don't have a way to duplicate the tapered fit w/ my 10mm (i.e. .393") motor shaft. What I'm thinking is boring out the clutch plate hole to .465" and sleeving the motor shaft. A set screw will hold the clutch plate on the shaft but then I'll need a key/slot to keep it from spinning on the shaft. I'm still learning about this as I go. If anyone has any good ideas I'm all ears.

 

[Deluge]

That's a tricky one, dude.