Sd.Kfz.250 R/C?

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dankovich

Sd.Kfz.250 R/C?

Post by dankovich » Tue Jul 26, 2005 9:44 pm

Hi everyone
Have just acquired an Armorhobbies Sd.Kfz. 250 Alte, and was wondering if anyone has any thoughts or suggestions on how to R/C one of these babies up, so the boys of FJR6 dont need to walk anymore.

thanks danko

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Re: Sd.Kfz.250 R/C?

Post by FUNKER » Mon Jul 31, 2006 4:43 pm

Yes, that would be very useful!
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Re: Sd.Kfz.250 R/C?

Post by plastic scouser » Mon Jul 31, 2006 6:38 pm

Look down the page at newbie with a question it is explained on this also check this linkhttp://www.sixtharmygroup.com/portal/viewtopic.php?t=6119

Cheers Ian

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Re: Sd.Kfz.250 R/C?

Post by 007Kiwi » Tue Aug 01, 2006 10:43 pm

Was wondering on this project if the possibility of using Tamiya 1/16th tank Gearboxes would work just as well? I have 2 spare now.

Anyone thought about this?

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Re: Sd.Kfz.250 R/C?

Post by FUNKER » Wed Aug 02, 2006 10:10 am

Yes I have been thinking about just that, but we need the internal dimensions of the 251 and Tamiya exterior dimensions plus something else that we do not know about.
Patrick

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Re: Sd.Kfz.250 R/C?

Post by 007Kiwi » Thu Aug 03, 2006 6:03 am

whys that? we can put the 2 x (left and right) gearboxs where ever u want.

the 250 is wider than my tamiya. and you wouldnt need a diff in this case, just a splitter for the ESC
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Re: Sd.Kfz.250 R/C?

Post by Humpy » Thu Aug 03, 2006 9:17 am

Chaps,

Noel Dollimore (Endee on the Forum) has done this already. If memory serves me right he used a Tamiya truck (King Hauler?) motor, gearbox and diff and modified the floor a little so that the motor and gearbox sits under the bonnet and the diff under the transmission hump. With the plastic tracks it's obviously got to be treated with care but does make a usefull little RC model. Over to you Noel.....

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Re: Sd.Kfz.250 R/C?

Post by 007Kiwi » Thu Aug 03, 2006 9:30 am

Thanks Humpy, Saw endee's post a super idea of his to do that.

But I was wondering (out loud) if Tamiya Tiger gearbox's would sort of do the same thing. I have'nt worked out how to attach the drive wheels yet

I'll cry if I have to use my Merc as a Donor :cry: :cry: :cry: :cry:
(even though it aint finished)

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Re: Sd.Kfz.250 R/C?

Post by endee » Thu Aug 03, 2006 10:24 pm

Hi Guys.

Yes I used a Tamiya King Hauler Motor and Gearbox and an HPI diff which all came from good old Ebay, you can often find them lurking around there.
I've had some experience of splitting drive across esc's and whilst the theory is good but in practice the drive can become unbalanced, i.e. when going in a straight line all may be ok, but when you start to steer, unless you are very careful with the throttle, as one track slows down the other experiences more drag and therefore has to be driven harder, which can result in the turn becoming much tighter than was planned or faster than required due to overcoming the drag losses. This method can take a lot of getting used to, ask Funker as he was experiencing a similar effect with his 251, which we discussed at Duxford.
My reason for using a diff is that the drive stays constant for the speed of the motor and when a turn is made, as with a wheeled vehicle, as one track slows the other automatically speeds up to maintain the current speed without having to increase power to compensate. There is no appreciable drag on any track so no added stresses and a smooth turn results.
If you want to replicate the original, use a diff and fit brakes on each drive sprocket shaft operated via the steering system so that for a slight turn it relies just on the front wheel angle whereas for a tighter turn the relevant brake is operated which will slow one track and therefore induce a tighter turn via the tracks. Now theres a challenge !!!!!!!!

Hope this helps.

Noel.
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Re: Sd.Kfz.250 R/C?

Post by 007Kiwi » Thu Aug 03, 2006 11:43 pm

Heh Endee I bow to your wisdom in this one... Not on your Nelly springs to mind on the brake idea.... :roll:

My poor Merc's gonna have to cough up its 3-1 gearing reduced 3spd box and diff.... *sigh*

(The 3-1 unit gives it a heap of low down torque) I might leave that onthe box as well!

Thanks Endee for clearing that up for us.

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Re: Sd.Kfz.250 R/C?

Post by plastic scouser » Fri Aug 04, 2006 7:53 pm

Hey Endee any chance of some pics on how you attatched your steering servo :?

Cheers Ian

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Re: Sd.Kfz.250 R/C?

Post by endee » Fri Aug 04, 2006 10:37 pm

Hi Ian.
Hopefully here's a couple of pics regarding steering servo placement and connections.
Servo is mounted directly beneath motor and servo horn projects downwards through slot in floor where plastic steering column should come through.
I made a new track rod from square brass tubing as I did'nt consider the plastic one to be robust enough.
The steering servo horn is connected to the track rod via a small steel rod with ball joint sockets at each end and the respective ball ends fitted to the horn and track rod.
Last edited by endee on Fri Aug 04, 2006 10:54 pm, edited 1 time in total.
Knowledge is of no value unless it's shared, if you can remember it !!!!

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Re: Sd.Kfz.250 R/C?

Post by endee » Fri Aug 04, 2006 10:51 pm

OOpps pictures did'nt work, sorry, I'll have to try to work out how to get them on here.
If anyones got any ideas I'd be grateful, Iv'e got a Photobucket account but am still trying to learn how to use it.
It's not so easy for us oldun's to grasp this wizardry you know.
Cheers, Noel.
Knowledge is of no value unless it's shared, if you can remember it !!!!

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Re: Sd.Kfz.250 R/C?

Post by endee » Fri Aug 04, 2006 11:14 pm

Image
Steering servo location under motor.


Image

New track rod and servo connection.


Yippeee !!!!! 'Cracked it'. Well hows about that then, this olduns not so dumb after all.

No comments on that subject thank you.


Here's an extra pic which may help anyone having a go at R/C ing one of these.
It's the drive train installation.

Image

Good luck with your projects, Noel.
Knowledge is of no value unless it's shared, if you can remember it !!!!

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Re: Sd.Kfz.250 R/C?

Post by 007Kiwi » Sun Aug 06, 2006 2:14 am

Thanks Noel, Thats really helpful of you 8)

Cheers

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