RC India

hi guys....
i really want to know if i can make an rc car with dc electric motors(stepper-first prefrence,servo,brushless).
please tell me which one of the above is the best.
plus i want to add some suspensions for better control and some sensors too...
actully i think arduino is the best platform(am i right??) for this project.
please give me any idea.....
.
.
.
my buget is upto 15000rs.

With electric power, I doubt whether you can reach 200 mph...(nearly 360 kmph)
You can try with a nitro on road car...

It's possible to reach speeds you've mentioned with electric power. Nic Case just hit 180 something mph recently.

With your budget, it'll be hard to reach the speeds you want.

Speed run cars use high Kv inrunner motors at high voltage and are set up so that they can run safely for just a few passes. They are geared high.

A lot of aero work goes in at high speed. It'll take a load of experience to know what works and what doesn't.

Tires are also a consideration. Rubber tires deform at high speeds and foam tires are preferred.

How would sensors help the run? A typical RC gyro might help keeping the front pointed straight but anything more seems unnecessary.

Take a look at high speed builds on the forums and you'll get an idea.

hi u ve mentioned stepper motor, n ur also asking us to help for ur project. my suggestion u first help yourself n read some articles n contents over motors, how can u even think of a stepper motor. so the bottom line is we are ready to help provided u should also take some strain. don't misunderstand me but wat I am saying is valid n is to help u.

^+1

Stepper motors are optimised to operate in little steps, with less axial speed. So brushless and brushed motors are the only option. 15k? really? Almost impossible. To achieve high speeds, you need to learn the behaviour of the car at different speeds. High speeds on any platform, is a  different ball game altogether.. play safe.. And welcome to RCI..

tats what I was taking about, stepper motors the name itself suggests that it ll rotate in small steps. plus in order to stop it again we to provide supply. so ritul welcome to rci n all the best for ur project. I really liked the concept very much.

Select a motor or engine that can provide 17083 rpm at ground .
You will touch a speed of 200 miles / hr :-)

^^ You need a specific wheel size for that figure to give you a theoretical speed of 200mph.

When one starts actual speed runs, theoretical calculations can only give a rough estimate about how fast the car can go.

Yaa , I forgot to mention that this calculation is for 5 cm diameter wheels ..

Larger the diameter of wheels , less rpm required and more torque required .
Also this rpm value is at ground . So actual rpm value at motor shaft may be much high .

Like I said earlier, it works on paper but many factors come into play when you start actual runs.

yes lot many factors n with this steep budget its going to be more difficult.

either you have a goal or a budget, not both :-) you can get a high kv motor with a large battery. but then you will need an advanced cooling system. Then the tyres will need to be strong enough. then you will need appropriate aero dynamics to ensure that the car does not fly off.

No goal is impossible...

@ritul
Sir,
200mph is about 300ft/sec.
Or 600ft for a 2 sec run.
Say another 300ft for acceleration, and 300 for braking.
So you'll need a track/runway of some 1200ft/400m!

Have you built/run a less ambitious car yet? Or is this your first attempt?

Perhaps you could consider making a tethered car first, that can be run in a limited space like a basketball or tennis court.

but the question is where is ritul. there is no further update from him.

Team associated official Team has been trying now for years now to hit the 200mph speed but have not succeeded .

I suggest you first research on this .You don't even know about basics of motors.

Best answer awarded :-)

i've done some goofing on google about motors lately.
and it seems that if we increse the steps we can get higher rps.
brushed motors have higher accleration.while brusheless have high torque.(if i'm wrong please correct me.i am just an new ass around.)
secondly we will not need special breaking system as we can make the motor run backwards(obviously this will cause burnout.and who hates the smell of burning tyres??)...

secondly 200 mph is just a figure of speech.
if my car reaches 50mph it will be a greate achivement.
FYI niccase was able to reach 196mph...

and please someone post about electronics and programming platforms.....

Figure of speech, eh?
And here we were thinking you were really serious!
Teaches us to henceforth take topic headings with a pinch of salt.

Remember i had asked you if you had built/run a less ambitious car yet, or was this your first attempt?

Now we know.

You weren't very clear with your "figure of speech".

Forget about using stepper motors for this. Go brushless. 50mph is not hard to achieve with the right combo.

Braking on motors (BL) is achieved by alternately shorting the windings. Running the motor backwards while running forward will cause major mechanical damage. You'll have much more to worry about than a "burnout".

Well Bro with all due respect, will you tell about yourself, I mean what you do and about your professional background. Even if you are a student please tell us about your domain. BTW The increase in steps here doesn't refers to stepper motor. So if you tell us about your domain then someone will surely point you in the right direction.

i am currently doing second year mechanical engg.

okay so now u need to look into dc motors. u ve already study basic electrical so it ll easier to understand motors. there are different types of motors. u go through it. n forget about stepper motor as of now. there are some basic formulas or relationship for motors n there capacity. KK sir has recently started a technical topic, u ll get a lot of info, just go through it. and my suggestion is follow KK sirs advice, first build a normal car don't worry about the speed, this ll make you understand the practical aspects as well as the behaviour of the vehicle. Keep a high goal but start from scratch. build a simple car first. here there is no need of programming, u can just run your car without any programming. regarding the wireless control, browse over youtube u ll get lot of videos on how to configure it.so go on start the process n then if u find any difficulties the forum is always ready to help.

I like the momentum of the thread.. just to know the feel of how even sub-200kmph, have a look at this video. http://www.facebook.com/video.php?v=456556661150705 (http://www.facebook.com/video.php?v=456556661150705)

Handling is the issue, when speed catches up, the controls become more and more responsive/sensitive. so difficult to control the handling of the car. the center of gravity has to be perfect, the weight transfer in an event of acceleration, braking, cornering has to be spot on. As Iyer sir said, you will need a special test/run surface without any imperfections and most importantly, no traffic [human or vehicle] to have a safe run. Keep the thread alive with the progress of your project, and you will definitely get the necessary pointers for it. all the best!!

As suggested earlier, try a tethered car, which can be run on a basketball or tennis court.
It will postpone steering related issues for later, after you get the car running!

Followers of this thread may like to see AnjanBabu sir's thread:
http://www.rcindia.org/cars/(build-log)-3-wheeled-rc-car-sweepstakes-2014/msg186345/#msg186345 (http://www.rcindia.org/cars/(build-log)-3-wheeled-rc-car-sweepstakes-2014/msg186345/#msg186345)

all right...
i've found some top rc hobby sites viz. hobbyking,bananahobbies,rcplanet,hobbytron and many more....
which one is the best to start from scratch???
(i feel like they are too expensive).
 btw i hate online shopping....
are there any shops in mumbai or thane where i can get the parts at lower cost??

there are in mumbai but all are online. but I doubt there is any car related thing in mumbai, I am not sure. but u ll get the motors n escs in mumbai.

Hobbyking cheapest option for beginners.

Testing is a very important part... I got myself a thunder tiger go kart, and put a 2200 3s on it... Was trying to see how fast I could go and I hit a small stone. A stone. 😐
The car just took off. It went spinning into the air and rolled across the road.. Broke the servo control horn so now can't drive for sometime 😕
And this wasn't too fast, but even something like a small stone can be dangerous for a small car going at 100+ kmph...

+1 to that. What you might consider smooth tarmac will be a crater field for your small rc car. Check out the Traxxas XO1 videos. Look where they do their speed runs :D

High gearing will work. You may need a bigger motor.

 Brakes can be applied using brushless motors. No need to run the motor back wards, the speed controller will take care of it.

Torque and other characteristics of brushed and brushless are somewhat same for the application you are plannig just that brushless is less maintainence since there is no contact brush to clean. You may actually be better off using a brushed motor since the esc is much simpler. You just have to control the voltage to the motor.