Gas R/C Car

[Iceman_Chris]

Hi,

Me and my friend are designing a Remote Control Car with a steel frame, 4hp 2-stroke engine, and RF control. My friend is doing the mechanics as I'm not great with engines myself but I am doing the electronics. I plan to use some PICs I sampled from microchip.com. I would have the PIC take the input from the controller and send serial data to a RF module (I'm not sure which to buy... trying to save money...). The module on the car would receive the data and decode it with the PIC and have the PIC output PWM to the throttle servo. What I'm not sure about is the steering. I can't change the amount of power going into the wheels separately (We're using a centrifugal clutch attached via belt to the axle) and I don't want to have to buy an expensive servo to move the front wheels. Any help would be appreciated...

Thanks, Chris

 

[moody07747]

WOW :shock: 4 HP
now thats the type of power i like to see in an RC car

sounds like a great project
cant wait for those pics

how are you assembling the metal frame, (Welds, bolts...) :?:

 

[audioguru]

Hi Chris,
Very cheap steering methods as used on kids' toys:
1) Straight when forward, turn one direction by braking one wheel when in reverse.
2) On micro RC cars, a solenoid applied full left or right steering. A spring centered the steering. They were really difficult to steer.
Your choice. 8)

 

[Iceman_Chris]

Hi,

We're planning on welding the whole thing together and if later on we find other stuff we want to mount on it (such as a 12 gauge lol :wink we can bolt it on. Steering is going to be difficult... I even considered using an electromagnet to pull the wheels left and right since I'd have abundant electricity for the magnet from the alternator (he found one in his backyard ). Thanks for the suggestions, any more ideas would be greatly appreciated.

Also, please note that I'm 15 and don't have unlimited cash lol...

Thanks, Chris

 

[pike]

LOL your just like me ( and maybe zachtheterible) cocky.

Believe me when i say it will be expensive. You will be emptying your wallet for the electronics. Do you have field experience with PICs?? are you good with radio equipment??

https://www.electro-tech-online.com/threads/wordgenerator-in-electronicsworkbenchmultisimv7.13188/

this thing cost me about $300 us to make, useless and serves no purpose.
now i'm still emtpying my wallet to pull togetehr a 5hp remote controlled mower. already cost me $200

edit : i'm 15 , i'm not exactly rolling in cash, but i pulled it off

 

[Iceman_Chris]

lol, thats good to know there are other people out there interested in the same stuff. It's even nicer to know that there's also teenagers as opposed to adults out there too. Anyways pike, I do have experience with PICs and I have a programmer and tons of samples from microchip.com. As for RF, there are so many different modules out there I'm not really sure which to get. I was thinking of making my own with just a simple crystal colpitts osciallator with a keyed power amplifier. Any tips would be nice.

Thanks, Chris

 

[Nigel Goodwin]

lol, thats good to know there are other people out there interested in the same stuff. It's even nicer to know that there's also teenagers as opposed to adults out there too. Anyways pike, I do have experience with PICs and I have a programmer and tons of samples from microchip.com. As for RF, there are so many different modules out there I'm not really sure which to get. I was thinking of making my own with just a simple crystal colpitts osciallator with a keyed power amplifier. Any tips would be nice.

I would suggest you stick to licence free radio modules, these are legal to use, any you make yourself will most probably be illegal!. I would also suggest you get modules with built-in Manchester encoding, they cost a little more, but are FAR easier to use - and more reliable as well.

As for your steering, you really need 'proper' steering, controlled by a servo, just like driving a radio controlled car!. As your machine is somewhat larger, a standard servo won't be anywhere near big enough, but how about building your own like this site **broken link removed**?.

 

[Klaus]

It would also pay to have a good look at the steering geometry of real cars or go carts, since your 4Hp steel frame remote model is not exactly a 'miniature'.
The pic on top of the page of the site that Nigel suggested for the servo, is NOT a good example of the steering linkage.
The short levers at each wheel, where the linkage rods attach, should angle slightly inwards. This produces an uneven angle for each wheel while steering around a curve. As each front wheel travels around a different radius curve when cornering this feature is recommended.

Getting this bit right will make the steering servo's work much easier.
For self centering you can experiment with a little toe in of the wheels.

This project sounds like some serious fun :wink:

Klaus

 

[jclaudii]

I have some Ideas.

Since you have such a big motor mount a power steering pump to the engine. One much like on a import car. Use its hydralic pressure and a small lightweight hydralic ram and a control valve. attach a servo to the control valve. Since this car can probally pull some g's when it is cornering, the solid stiff push of the hydralic ram will prove very strong.

design your own servo. I believe all it is, is a pentometer that measuers the resistance. You can then program your pic to accept a certain resistance as dead center and then negative that be left and positive that be right. You could use any high torque motor, such as drill motor or even a ATV starter.

Now for radio....If you do build whatever or buy whatever I would highly suggest a failsafe. I have a 1/10 r/c...this failsafe applies brakes and idles the engine down in case of radio loss or loss of power. This would almost be a must given th size of your machine. I would hate to see you neighbors fence get mutilated because of a dead transmitter battery LOL.

As far as radios go shouldt a control for flight control be adequate to control your onboard systems, they operate on fm frequencys and they can have I think up to six channels or so. This would allow for data to be sent and recieved from the controller.

Good luck

 

[Nigel Goodwin]

I have some Ideas.

Since you have such a big motor mount a power steering pump to the engine. One much like on a import car. Use its hydralic pressure and a small lightweight hydralic ram and a control valve. attach a servo to the control valve. Since this car can probally pull some g's when it is cornering, the solid stiff push of the hydralic ram will prove very strong.

My Fiat Punto has electrical power steering, I've no idea what it looks like?, but presumably it could be used as a servo? (or at least the basis of one?).

As far as radios go shouldt a control for flight control be adequate to control your onboard systems, they operate on fm frequencys and they can have I think up to six channels or so. This would allow for data to be sent and recieved from the controller.

It's illegal to use an aircraft R/C system for a ground based model, and quite rightly so! - you can get multichannel ground based R/C just as you can aircraft ones!.

 

[Iceman_Chris]

Hey,

Thanks for the ideas, I think I will put a failsafe on (I wouldn't mind the neighbours fence being mutilated but I would mind my $500 car being destroyed in the process ). I'm probably gunna end up making my own servo if I can't find another alternative. As for the radio module, if you guys know any sites (I have been to alot of them but I am interested in the ones based in Canada that sell SIP radio modules)then please suggest them.

Thanks alot, Chris

 

[chiba]

There are some inexpensive servo ideas on this RC Lawnmower page:

http://www.webcom.com/sknkwrks/mowers.htm

 

[mstechca]

Hi,

Me and my friend are designing a Remote Control Car with a steel frame, 4hp 2-stroke engine, and RF control. My friend is doing the mechanics as I'm not great with engines myself but I am doing the electronics. I plan to use some PICs I sampled from microchip.com. I would have the PIC take the input from the controller and send serial data to a RF module (I'm not sure which to buy... trying to save money...). The module on the car would receive the data and decode it with the PIC and have the PIC output PWM to the throttle servo. What I'm not sure about is the steering. I can't change the amount of power going into the wheels separately (We're using a centrifugal clutch attached via belt to the axle) and I don't want to have to buy an expensive servo to move the front wheels. Any help would be appreciated...

Thanks, Chris

CLEAN THE AIR! :!: :!: :!:
and here in canada, GAS IS EXPENSIVE!!!

Why not operate it on solar power? It is far cheaper doing that a year than gas. For example, if your solar panel car costed $500 and your gas powered car costed $100 a year, then 6 years later, your solar panel car will win, because it was only $500.

How about using 4 separate motors for each wheel, and when you turn the car, have the motors on one side go forward, and the motors on the other side go backward. for forward operation, all motors go forward. Then you will get good 360 degree turns with some wear and tear.

 

[audioguru]

Solar power for cars is a lot more expensive than gasoline. The solar cells cost a fortune as seen on the universities' cars that were endurance-raced and costed hundreds of thousands to millions of dollars each.

The solar cells are so inefficient that the car must weigh less than the driver. Cruising speed is low to save power. Etc.

 

[Iceman_Chris]

You can also get what I think is called 'purple gas' here in Canada which is just regular gas with about 15% off the regular price if it is not used for on-road driving (I think it is mean't for farmers and ATV's etc.) and that would save me money on gas. I'd love to make a solar panel car but each solar panel would probably cost about $300 and I am not planning to just keep this one car for 6 years. Thanks for the ideas though.

Chris

 

[Nigel Goodwin]

You can also get what I think is called 'purple gas' here in Canada which is just regular gas with about 15% off the regular price if it is not used for on-road driving (I think it is mean't for farmers and ATV's etc.) and that would save me money on gas. I'd love to make a solar panel car but each solar panel would probably cost about $300 and I am not planning to just keep this one car for 6 years. Thanks for the ideas though.

No, a solar powered version would be far too expensive, and far to large in order to carry enough cells.

As for special price fuel, we have it in the UK as well, it's called "red diesel", it's for use by farmers and quarry vehicles - it's only about 15% of the cost of regular fuel (which is FAR more expensive here - I currently pay £0.889 per litre for petrol). But if you're caught using it in a road car it's a VERY serious offence - it includes a special red dye to distinguish it, and a very small quantity of red diesel mixed with normal diesal turns the whole lot red!.

 

[ASKANA]

nice to hear about steerin techniques tht can be employed and abt the info about red diesel in UK

 

[audioguru]

Hi Nigel,
Do you drive a "stinkin' diesel"?

 

[Nigel Goodwin]

Hi Nigel,
Do you drive a "stinkin' diesel"?

No, I drive a 1.2L petrol Fiat Punto :lol: small and cheap to run!.

Although I do sometimes drive diesel vans at work, Citroen Berlingo's, which are pretty good diesels!.

 

[DragonMaster0121]

or you could use propane with a jet engine!!

the plans are here:
**broken link removed**

they are under construction right now but they will have 3 sizes available!!

Small: about 2' long and produces 20lbs of thrust.

Medium: about 3' long and produces 130lbs of thrust.

Large: not sure how long, produces 300lbs of thrust.

The engine is made of welded sheet metal and has no moving parts, so it can't wear out.

The fuel is propane and is fairly cheap to fill up.