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Remote Controlled Car frame design

  1. Jan 6, 2008 #1
    I am an engineering student and am participating in a RC Car raacing comp in my college. The comp requires us to contsruct a RC car using either DC motors or miniature IC engines (4cc-6cc). The track will have many obstacles like sand pits, oil spills etc. The objective is to complete the track in the shortst possible time.
    I want to know what kind of a frame/chassis should I opt for while building the car. I am not really sure of the importance of the frame in such a small car...will just a simple ladder frame suffice? Also, given the nature of the track, I am thinking of going for indpnt suspensons for each of the wheels. Is it possible to do it?
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  3. Jan 6, 2008 #2


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    Have a look at the Kyosho website for inspiration. You probably want to be making a little IC powered buggy, but I don't know what your constraints are. Fully independent suspension sounds like a given, you'll also want to consider suspension geometry and damping rates for optimum performance. Oh, and the lighter the better.


    If the other competitors are RC car enthusiasts, I'd suggest you go for something a bit more sophisticated thana ladder frame.
  4. Jan 7, 2008 #3


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    I've never had any exposure whatsoever to R/C racing (other than buying a cheap Radio Shack thing to scavenge the servos from). I'm estimating that if a 4-6cc motor is indicated, this thing can't be more than a foot long or so. After all, my weed-whacker has 30ccs. I do know a fair bit about how real 4 x 4's work, though, and for the serious stuff it's all about articulation and tread. Power is secondary, since that can be made up for with gearing.
    I have a thought about the articulation angle, but I would definitely defer to Brewnog's expertise in the matter if I'm off base. There are all kinds of long-throw suspension gadgets available for toy cars, and they seem to work really well. What I'm thinking of is using those kinds of parts, but making a semi-box or ladder frame out of flexible plastic such as polyethylene with metal mounting plates. My logic is telling me that it should provide a far more adaptable suspension, and there isn't enough weight to warrant a rigid frame.
    Last edited: Jan 8, 2008
  5. Jan 8, 2008 #4


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    The biggest question is: how much of this car has to be custom designed and fabricated, and how much of it can be off the shelf components? There are without a doubt very advanced OTS R/C cars out there that could navigate the course VERY quickly, so you'll want to look at those designs for inspiration. I would go to your local R/C store and look at what exists out there, and navigate to www.towerhobbies.com as they have almost everything R/C there.

    Are you going to want to go 2wd or 4wd? Nitro or Electric? I would say you design would be simpler if you used electric, but if you're in it to win it nitro will be lighter and more powerful. You can get a LOT of power out of a nitro IC engine. In off-road nitro engines, 4-6cc is a BIG engine; take for example the HPI K4.6 High Output Hellfire Engine, it's a 4.6cc engine (which is considered a big block in RC land) and puts down 2.95hp at 38,000 rpms. Problem is, it will require a transmission and centrifugal clutch to make it work, can you use existing components for that?

    For chassis and suspension, I would definitely go to a local hobby store and look at what already exists before you begin reinventing the wheel. Depending on the obstacles you'll have to navigate, you will probably be most interested in a buggy or stadium truck approach, keeping things as small (and as light) as you can. Depending on what kind of parts you need to design, and what you can use off the shelf, a hobby store will be you best friend.
  6. Jan 8, 2008 #5

    They make the highest quality RC car parts.
  7. Jan 8, 2008 #6


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  8. Jan 12, 2008 #7
    @ Mech Engineer:
    i was thinking of using an IC engine...but as u said the clutching n tansmission assembly is a problem. i can use readymade components for them...but here availability is a problem. can manage it tho. the other thing was the steering assembly...are readymade assemblies available?
  9. Jan 14, 2008 #8


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    You will be able to find complete transmissions and clutches that can be bought as replacement parts from either hobby stores or www.towerhobbies.com, for example:


    This is a full replacement transmission for a Traxxas T-Maxx. It is compatible with 2wd or 4wd applications, and includes a disc brake for servo-actuated brakes. If you look at how the transmission is used in a fully assembled T-maxx, you will see one servo is used to control throttle and brakes, using a simple lever system. I'm sure you can find similar products from other manufacturers.

    As for steering, that should be an easy application after looking at existing designs. All you will need is two steering knuckles with bearings, a servo, and some links to tie it all together. it's difficult to explain, you will need to go to a hobby store and see for yourself.
  10. Sep 2, 2011 #9
    If the track consists of sand and oil, it seems to me one of the major problems will be spinning wheels. The more powerful the car, the worse the problem. With electric 2WD, the undriven wheels could serve as a reference and limit how much faster the driven wheels can turn. With electric 4WD, if all motors are supplied the same voltage, one wheel could spin faster than the others only with the loss of a proportionate amount of torque.
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