RC India

I am a 3rd year BE Mech student and I want to participate in a RC Car race event held in our college.

We are supposed to design the chassis and steering mechanism of the RC, the rest of the parts can be bought from the market. Right now, I have absolutely zero knowledge about RC cars and also how I will be able to design its chassis and steering mechanism. So, I will be very thankful if u can guide me through the basics of an RC car and what makes it tick on the race track.

Sorry if there is already an existing thread which explains these details. I searched the forum and failed to obtain info regarding this. If there is such a thread plz post the link to the thread and I will be very much happy to go through it.

Thank you.

Hey
Welcome to the forum! :)

Most off-road cars have a tub style chassis or a flat plate aluminium chassis.
Like this: http://www.gshobby.com/images/Traxxas/TRA5822-450.jpg

Lot of bigger off-road vehicles are using this: http://www.snrgraphite.com/images/SNRA3000.jpg

The picture here is of a Carbon Fibre chassis, but you get aluminium chassis as well.

Steering:

Upto my knowledge, most cars use a bell crank steering.
Like this (http://www.google.co.in/imgres?q=bell+crank+steering&um=1&hl=en&client=firefox-a&sa=N&rls=org.mozilla:en-US:official&biw=1920&bih=978&tbm=isch&tbnid=fSySkgdTRpOvfM:&imgrefurl=http://www.traxxas.ru/products/electric/emaxx3905/trx_emaxx3905.htm&docid=242miKVgGK_ByM&w=800&h=472&ei=two-TpW0GcmqrAe8v8GGBA&zoom=1)

Divyam has it spot on.Few off-road vars use a CF chassis.On a nitro,you want a flat plate aluminium chassis with kick up for better performance.

The Losi 22 uses a slider style steering.I would suggest you stick to the traditional bellcrank style.

Might sound foolish, but u cant make a bell crank steering yourself...if it would have been so easy.,every toy must come with one.
I would rather suggest you to pick some idea from a toy grade vehicle,since it has a relatively simpler design to mould/build.

Sashi..its too easy to make a steering mechanism,for your car, may be big or small..first of all find 4 wheels for you, and make two holding mechanism,for the front wheel set..make two identical base, to hold the wheel holders with slight castor,and by adding two drive arms, on the holder, you can steer it with a micro servo, for a mini one,  and 5 kg servo for a big one.if you have a slider servo,it will be more easier to do..and if you are with independent toy or a 30 rpm gear box, it will be even more easier..with this type you can split it in to two, so you can add independent suspensions on it..while talking you may feel it as a big thing in going..but once you see the mechanism,it will clear... :thumbsup:

one of the other option is finding a big scraped toy..some toys are equipped with good quality steering system, and differentials..you can make a simple steering mechanism, by using two identical servos. the only thing that you have to remember that, in some cases, you have to change the polarity of the servo motor once, to attain same directional rotation. with this setup, you can individual fix two wheels over a suspension mechanism, as it need not a drive rod...as all servos are designed for a same criteria, it works nicely..i always use this type on my amphibian vehicles..

another mode of steering mechanism, is made out of a lens driving mechanism of a DVD player..by adding a sliding volume control to the same lens base you can get a good proportional ratio...

another simple option is the teethed belt. after making the wheel holders, you can extent it's shaft to upper level, then can fix two teethed pulleys, can drive with teethed belt. such pulleys and 10, to 40 rpm gear boxes can be purchased from many companies all over India. it took only 250/- :Rs: for the gear boxes..

after making the steering mechanism, you can add dampers, the dampers made out of injection syringes..but you must fill the syringes with hydraulic viscous fluids to damp any action...


i will post some of my works here so you will get some idea the how simple it is... :thumbsup:

you can make chassis from styroflex sheets, for lighter applications,(on roader), with wooden reapers for off roads, and for extreme, can make from square or T shaped aluminum channels. this alum chassis is capable to withstand jumping forces and extreme crashes..

you can make the chassis aluminum chassis in to split, from center, so your craft will be an articulated one..by adding two simple springs in both sides, your craft will be far versatile on a rough ground.

you can choose type of the suspension, as compression, or expansion..for compression type, you can fix springs and struts,(motor cycle spoke), top of the chassis, while, can add these at the bottom, of the craft, with a simple PRO arm.so the arm will pull the strut in reverse of the compression, and in my experience, this type gave me more versatile performance at beaches and sand..

if you haven't a bipolar ESC and brushless, you can use your 4 channel radio, in to twin stick mode, by removing the spring from the second stick.so, you can select the forward, and reverse by the right hand stick, while the left hand, acts as the throttle.you can also, use the right hand stick, as a gear shifter, if you add a comparator circuit in your configuration.this will give you a traction control while cruise. a comparation between front and rear wheel set is also possible,in the case of 4WD mechanism.

DIFFERENTIALS...are costlier if you buy from a reputed company..most of them may by brass or magnesium alloys..but you can find some good heavy duty differentials on good toys..the gear teeths are heavy and good in quality..i always wander all over the junkyards and scrapyards to collect the differentials, from toys, and can make a good one from the wiper motors assy of a car, or an autorikshaw..for engined one..

and for lighter applications you can choose toy differentials..

one of the easiest method to make a differential is electronic. with infrared led sensing system, it will give you a better performance especially in a sudden cornering. in this setup, you can fix two of the drive wheels, or 4, independently..as 100%..but must be in a same line, (AXIS), if not, the electronic circuit will not respond properly..i use this system on my high performance crafts..by adding some more additional electronic circuits, you can get a nice traction control and instant braking..

motors..you can choose any motor, appropriate to you, but you must rework on it...by rewinding up to our specs it will works nicely...or can go for any motor that you can...
 :thumbsup: :thumbsup: :hatsoff:
so options are many...and i hope, as a engineering student, you have some good idea to follow...nothing is complicated if you have a will and interest..nowadays all motors, radios, esc s, batteries are getting inexpensive...so options are many...

another exciting option is customizing your TX in to a good unit with a steering.you can collect thrown, or used steering when consoles from a computer shop, then make a wooden base, with plywood, and can fix the potentiometer, of your TX under the steering wheel, and throttle, potentiometer in to the leafs under the steering, and FWD + REV on the selector switches..will be more realistic and exciting..you can also add a vibration sensor, in to your steering console, so i will give some vibration feel while cornering...wrooommmm.... :thumbsup: :hatsoff:

i will post many of my simple steering mechanisms and platforms here, but not now, because i have to photograph it all once again...then you will get the idea how simple it is..and also post some videos of the same crafts, so you can get a clear idea how nice it performs...have a nice drive.. :salute:

here i am posting two more photographs, of my new creation..all it made out of scratch, steering mechanism is made out of handy things, include aluminum sheet, derived from a kitchen vessel lid, and the differential is from an old scraped toy. i replaced its counter gear and laygear,  by a brass gear set, from an old clock.but this altered the final torque to even higher. it also eliminates the convenience of hi and low gear selection..she is 2 feet long one..powered by a rewoked toy motor, she is too fast, and drifts even on tarmac..i will add all lights and fittings later..so you can see how simple is to make a RC vehicle...now she is powered by a toy RC...

sorry for the repeated postings..my server is too slow...ohh...
here is..she is almost finished... (:|~

and if you are using an IC engine, you can make a clutch simply from a brass dowel, in to 2 inches, as turning out from a lathe, in to a bowl shape, X 2 nos, with thread in ones outer periphery. then make two turbines that must within the bowl, and can fix it facing each other, inside the bowl chamber..the chamber must be filled with high viscous hydraulic fluid. so, you can transfer the power from engine, to the drive train, in a smooth way..

another simple mode of clutch is centrifugal, means can make from metal dowel, in to 2 inches, with an inner plate that holds 6 or 8 bicycle balls, in a ramp. when engine starts to rotate, the balls will thrown to the outer  and grabs the inner wall of the clutch bell made out of metal dowel..

but nowadays motors, especially brush less motors are entering in to an extremely powerful mode, so i hope you can use a good brush less setup, instead of a IC engine. because it will make easy your efforts..but result will be same...

I might sound like a moderator,but please avoid making multiple posts, u can use the edit  option to  further add info in your previous post. It will look more neat.
No offense

Thank u very much for all the replies....

I will look into everyone of them and decide on the best alternative...

Since all I am is really a beginner, I am getting confused regarding what actually constitutes an RC car, so that I can go step by step.

So, I will be very grateful if u  can list all the items I need to make an RC car.

The car must be propelled by an IC engine(4.5cc max) only and I should design my own chassis and steering mechanism, the electric voltage anywhr in the machine should not exceed 12 V. These are the main criteria.

And this car is intended for purely racing purposes.

Keeping these factors in mind, if u can list the things I need to get to build the car form scratch, I will be very grateful.

You need to start looking at nitro cars.Listing out the components will be really hard. You can buy a used nitro buggy and make your own chassis and steering assembly.

traxxrc1..i am too sorry for the inconvenience, about the multiple posting..that's because i have a very limited connectivity with me..i am using a modem from Idea's net setter, and its too slow..and i already mentioned about that..and further option is not possible..sorry..and i am posting some of my idea, not for any business purpose, but only to share..i hope by spending lots of time in front of the computer, some of my friends get some idea from my works..again i apologize for the inconvenience..

1 doubt guys . should you break in a nitro car engine each and everytime you run the car or just once when u first buy the car

Please take the effort to see what thread you are posting in. A "break- in" is done only once.

for the entire lifetime of the car only once huh

can't we use 4 dc motor for 4 wheels  of 200 rmp  ?