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-   -   Savage XL outrunner conversion (https://www.rc-monster.com/forum/showthread.php?t=25847)

DanteX 04.02.2010 04:43 PM

*Update*

I received the outrunner today, and it is bigger than i thought.
But it fits pretty good actually.

I started to look for an aluminum motor mount and i finally cut an old rc chassis to fit.
I bent it and drilled the holes (there were holes before too :lol: )
And here are few pics:

Before:
http://www.abload.de/img/dscn16557snc.jpg

Motor comparison: the can-motor used before and the outrunner

http://www.abload.de/img/dscn1654jolr.jpg

Then a picture after my work:

http://www.abload.de/img/dscn1656gsh2.jpg

And some detail-shots:

http://www.abload.de/img/dscn1658mr2z.jpg
http://www.abload.de/img/dscn1657jqlg.jpg
The bending looks way more worse and it really is. :whistle:

Thats all for now!

Regards, Andy :yipi:

Manne 04.03.2010 08:07 AM

Intresting project for sure:). Just a question, I thought the outrunner would be at least as long as the can motor? and doesn´t grass and stuff get stuck in/on the motor?:angel:

Keep up the good work! :whip:

DanteX 04.03.2010 08:32 AM

Yes, indeed i have to think about an appropriate dust protection and cooling solution.

Quote:

at least as long as the can motor
Why did you think so?


Q: Would it be enough if i cut a notch into the shaft of the motor instead of a end-to-end drill-hole?

Thanks
Regards, DanteX

Manne 04.03.2010 08:46 AM

It just felt like with a directdrive system you would be in need of a HUGE amount of torque to get the rig moving without too much cogging, and i was thinking "longer motor, more torq" so I´ve got suprised when I saw how short it was:whip:

DanteX 04.03.2010 10:17 AM

Next week i will see how it performs and then tell you if it worked :)

Happy Easter!

Manne 04.03.2010 10:19 AM

Sounds good. Happy easter on you too:yipi:

suicideneil 04.03.2010 03:14 PM

If by notch you mean a flat spot to attach the drive cups, that'll work fine- maybe add a little dimple too for the setscrew to bite into.

DanteX 04.03.2010 04:07 PM

Thanks, thats what i was talking of.

I will try it like you said!

DanteX 04.08.2010 12:45 PM

WTF?!

Well, a few minutes ago i completed the reassembly of the savage and i did a test drive.

But this thing has no power. It can barely get speed.

If i let the wheels spin freely it balloons that much.

I think there was something wrong with the scriptasylum calculation.
I had to stop the test because the motor got almost too hot.

Any suggestions for improvement?

Semi Pro 04.08.2010 07:33 PM

Quote:

Originally Posted by DanteX (Post 358495)
*Update*



Motor comparison: the can-motor used before and the outrunner

http://www.abload.de/img/dscn1654jolr.jpg

:yipi:

we put that exact same motor in an emaxx, just some advise, take it apart and reshrink the stator leads and then ca them down, or the motor will eat them for lunch

Semi Pro 04.08.2010 07:37 PM

Quote:

Originally Posted by Manne (Post 358590)
It just felt like with a directdrive system you would be in need of a HUGE amount of torque to get the rig moving without too much cogging, and i was thinking "longer motor, more torq" so I´ve got suprised when I saw how short it was:whip:

its going to cogg:lol:

its not the length it the diameter that makes a big diffrence in torque with outrunners, to not cogg you would need an outrunnertwice that size

simplechamp 04.08.2010 08:14 PM

Quote:

Originally Posted by DanteX (Post 359360)
WTF?!

Well, a few minutes ago i completed the reassembly of the savage and i did a test drive.

But this thing has no power. It can barely get speed.

If i let the wheels spin freely it balloons that much.

I think there was something wrong with the scriptasylum calculation.
I had to stop the test because the motor got almost too hot.

Any suggestions for improvement?

The values you used in the calculations are correct, but physics makes the calculated speed impossible with this setup.

Look at your rollout values, they are over 6:1. This means for every 1 turn of the motor the wheel will roll 6 inches, which is WAY too much. Should be closer to between 1:1 and 2:1.

With that high rollout you will have no torque at all, even with a low-kv torque heavy motor, because there just isn't enough gear reduction. That would explain why if you pick it up off the ground and let it freewheel in the air the tires might balloon huge, but once the motor is loaded up with the truck on the ground it can't get up to speed. It would also explain why the motor got so hot.

Semi Pro 04.08.2010 09:20 PM

what kv motor did you get?


we were geared for 40mph and it spun the wheels all the way to 30 on 5cell..........just didnt last long

simplechamp 04.08.2010 09:25 PM

Quote:

Originally Posted by Semi Pro (Post 359449)
what kv motor did you get?


we were geared for 40mph and it spun the wheels all the way to 30 on 5cell..........just didnt last long

Was the E-maxx direct drive though? You probably had a pinion/spur and transmission which all lowered the gearing.

Semi Pro 04.08.2010 09:26 PM

Quote:

Originally Posted by simplechamp (Post 359450)
Was the E-maxx direct drive though? You probably had a pinion/spur and transmission which all lowered the gearing.

no it was direct drive, let me see if i can find pictures for you


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