HellTriX

iTrader: (1)

First I will state that I'm a physics student working my way to a goal of PH.D in theoretical, quantum, and atomic physics, with minors in mathematics, electrical engineering (already have most of this done), and some engineering.

I've always done things that people say I'm reinventing the wheel when in fact I'm just bored and do things for the sake of building for my own enjoyment.

Now that that's out of the way. As a very first step I'd like to just throw out a question before I dig too much to see what would be the rules if I decided to do my own carbon fiber chassis of a 1:10 scale. I would design most of the stuff myself using my CAD, CNC, lathe, etc. For the more complicated parts I could maybe order hopups of things like differentials, and belt pulleys/shafts. Maybe even borrow A-arms (though I think I want to make my own). So by the end I'd have my own custom 1:10 with 50-80% all my own custom parts and the rest off the shelf hopup parts.

Would a car fitting my design goals be eligible for races where I won't find it extremely difficult finding others in my same class?

Ok I will leave it at this for now and see what kind of responses I get before I look any further. Studying for finals anyway.

Thanks.

niznai

That is very nice. I wish you success.

What exactly is the proposed topic of your PhD dissertation?

Reinventing the wheel is the key to progress.

About R/C cars.
There are various rules but nothing precludes specifically you racing your own design. If you look it up on the web you will see the various regulations.

I assume you want to build a touring car. If not, then don't read below.

Most rules specify that you need to have a 4wd car (there are 2wd cars as well). There are rules that define size pretty accurately (with narrow limits for length, wheelbase, width). For reasons of practicality I suggest you try to keep as close as possible to the standard wheelbase. Width is pretty much set as standard at 190mm so there's no wiggle room there (assuming you want to stick to electric touring cars. There are nitro TC and they are limited at 200mm). For wheelbase, there is a little bit. Sticking with the norm will also have the benefit that you can use comercially available bodyshells in case you don't want to make your own.

Again for practicality reasons you might want to look at some of the most popular touring car kits on the market just so you take on board the developments of modern technology. Chassis thickness for instance seems to revolve around 2.5mm thick lower chassis for more flex or 3mm for stiffer chassies. This has important implications for the handling characteristics of your car. Top chassis plate seems to be either 2 or 2.5 mm in most cases, so again that gives you an idea where to start.

Moving on to drivetrain type there two at the moment with their own applications. Belt drive and shat drive. Shaft drive cars seem to have issues with torque steering (just like real cars) when you motor's power goes above certain values. Stock racing is about as competitive as you can get with a shaft drive car. There are though classes where you can race them quite successfully below that level of power.

Belt cars can have one, two or three belts and again experience shows the more belts you have, the more friction you add, so you lose some efficiency. Single belt cars limit your choice of transmission types in that that you can not have a center one way pulley (some rules state that you have to have four wheel brakes so then you can't have any one way device). The most popular choice then becomes the two belt arrangement and if you look around you'll see this is what 99.99% of belt driven cars have.

There is a discussion of drivetrain efficiency compariosn between belt drive and shaft drive, or between various types of belt drive, but I won't go there yet.

Suspension and steering are pretty much limited as options but onemention here is the inboard suspension used on some cars mainly to allow lower profile bodies to be used.

I had my own ideas about car design too but rather than go out and start rom scratch (no time) I prefer to build my cars using readily available parts to create the best car I can starting from a certain platform. There's a large number to choose from and money is the limiting factor. Search long enough and you will find a lot of compatibility between various platforms, sometimes rather unexpectedly.

Good luck and keep us posted.

joe of loath

iTrader: (1)

If you're interested, I built my own. The build thread is here

If that's what a 16 year old and some free plastic can build, what might a PHD student be able to do?

CarbonJoe

If you want to race in any National level events that are ROAR sanctioned, you can't use *any* prototype parts in Stock classes. You would have to run Modified class. At the local level, I don't think that anyone would care.

joe of loath

iTrader: (1)

I think there's an exception for one off home built parts isn't there? I'm sure there is in the BRCA rules.

razzor

so long as the specifications listed in teh rules are met i dont see a hassle with it.
There is no restriction to what make of chassis only the min and max dimensions of certain parts etc..
Download teh ROAR or IFMAR rules and take note of technical specs and go for it

HzR

I'm currently in the process of designing a 1:10th scale touring car in a pretty similar way to what you want to do. I'm still working on the lay-out and packaging of the main parts.

When done, I'm planning on releasing all CAD-models and drawings for anyone to download to (hopefully) get more people started in designing their own cars.

I might even be able to give you a small head start : I just made a 3D-model of a touring car wheel and tire available for download.
Just go to drop.io/opensourcerc

I'm also trying to publish the whole designing process on OpenSourceRC.com, but haven't been able to update a lot lately, but I'm working on it.

I think you should definately go racing with it! It's the only way to see how well your ideas hold up in competition on the track. Just look at the Durango buggies to see what might come out of it. The guy who designed them just started it as a hobby project.

As some people said before, just make sure you follow the IFMAR rule book and you should be fine to enter races with the chassis. It's available for download at their site.

Good luck, and let us know how things are going!

jiml

iTrader: (3)

Unfortuantely, no.

Although this is a great exercise for you, and for us to see what you would come up with, the rules are written to prevent a "one off" car to be eligible. It would be far too easy for one company to break the bank to make one car to win one race. The cost of such a car would be so prohibitive that no one else would be able to compete, and people would drop out of racing in droves.

On the local level, you may be able to race if they allow it. While you may not be eligble to win, at least you would get an idea of how your design measures up with what is commerically available. And you should get some idea of vehicle dynamincs, and material weight versus strength.

You may want to consider model aircraft. There is much more room for engineering experimentation there, since the basic competition there is to take off, fly, and land without too much damage.

Good luck on your quest to be a rocket scientist!

Cpt.America

iTrader: (52)

Wow, one huge thread full of conflicting information

niznai

Would you care to elaborate on the rules you are referring to?

timmay70

iTrader: (5)

Jim is referring to the rules set out by ROAR that you cannnot race a prototype in anything but the modified classes. However, you should visit your own local track to find out what they allow. Most local tracks could care less, and are just looking for warm bodies. The ones that want to stagnate growth within the hobby, or want to rain on someone's parade can go eff themselves.

mac853

I think is acceptable, since the design is not so much radical and matches among other chassis.
Look, Kyosho isn't putting a prototype TF5 chassis in the race?
Don't you remember there is prototype made by DME from Switzerland in their TC nationals and European champs at 2 years ago, then until now there's no production version in the market, then so much more instead this 1, go here to see:http://www.overrc.com/index2.htm

Scott B

iTrader: (47)

Ya I would like to see these rules too. I believe you can run a "prototype" or one-off car in any modified or superstock class at a ROAR event, just not stock class's. And I'm sure you would be able to run any class at a club level.

seaball

iTrader: (9)

you won't believe where i found them ...

http://www.roarracing.com/downloads/..._Rule_Book.pdf

(page 86)

12.4.3 Vehicles, parts, and accessories used in Stock electric classes must be readily available through retail outlets at least 14 days prior to the event

i agree with timmay70. who cares. the spirit of the rule applies more to manufacturers than it does to the one-off designer/hobbiest. just go at it. make a car that fits within the confines of the equipment specs for whatever class you're intending to compete in, and cross the legality bridge if/and when you ever decide to run it in stock at a roar event. if your design presents that much of an advantage, it will likely be copied by &#^$, and will then become legal a few months later.

summary = totally useless to worry about right now.

Scott B

iTrader: (47)

Thanks, but I'm aware that "prototype" stuff is not allowed in "stock", I have read the ROAR rule book. The way jiml worded his post made it sound like "prototypes" are not allowed in ANY class.