Hi guys. I have a question. I am interested in learning how to create a radio activated ignition system for a rocket powered radio controlled car. I had a plan to do this by purchasing two radio controlled cars and using the circuit board on the second car as an ignition system for the rocket mounted on the first car. However, it was going to be costly to buy two radio controlled cars ( approximately 35- 40 dollars). I asked my friends to chip in some cash and I would build it, but they don't think I can do it. They are also cheapskates, every time we go out to eat they tip less than I do. I don't want to spend $40 on this, but I also don't want my friends to get away with thinking that I can't do this. So I am willing to spend no more than $20 on this. The radio controlled car plus the rockets will cost about $15. So this leaves $5 to spend on the ignition system. I figured it would be cheaper to build the ignition system myself, so that is why I am here. It is very important that I stay under budget so that after I successfully build this thing I can rub it in their faces how it only cost $20 and they are cheapskates who won't get to play with my new toy. I was reading your site and it is going along pretty well. I also downloaded a book (it was $100 and thus over budget, so I stole it). However, it is a LOT of reading. That book has 1,000 pages and even this web site takes a long time to get through. Also, I can not tell from what I've been reading whether I will be able to build this circuit after I finish all this reading.

So my question to you guys is:

What is the suggested reading for this AND will I be able to do this under budget (budget = $5)?

I am willing to cut corners to make this happen. For example, I don't own a soldering iron but it is OK because I do own a stove. Oh, also I am a graduate student in mathematics and have some background in physics. So I can skip all that stuff.

 

I strongly recommend against a radio controlled ignition for your rocket car.

Firstly, there is a high degree of probability that RF transmissions from other sources could inadvertently trigger your igniter, possibly causing personal injury.

Secondly, placing a rocket engine in even a small car represents an object that could cause significant injuries or property damage via kinetic energy once accelerated by the engine. With a sufficiently powerful engine, the car could become airborne, and then you would have absolutely no control over it. Since it would be aerodynamically unstable, it would loop around wildly until it ran out of fuel, or hit something.

If you absolutely MUST try it anyway despite the above dire warnings, then attach the car to a long stretched cable via a couple of screw-eyes, and use something soft and non-flammable to cushion the car to a stop at the far end of the run. A bunch of Ziplock bags filled 2/3 with water should make an effective brake.

Use a hard-wired igniter system that has a safety interlock (removeable pin). Estes sells a decent one, or you could build one yourself.

 

You sound like you have tried something like this before.

 

Wookie, I am not sure if your warnings, although valid, will be heard by the OP.

benimus,

I think the easiest way is to use a string, about 50ft or more, can be used to ignite the rocket. Maybe have the string pull a switch or an insulator out of two contacts, the contacts will short your battery to the igniter.

DIY electronics isn't cheap. I have spent 1000s on projects in the past and I am spending 1000s on my current hobby project. If there is a commercial way, 9 times out of 10, it's less expensive.

Steve

 

You sound like you have tried something like this before.

I blew up Mom's stove making rocket fuel as a young teenager.

I probably would've done it again if my Dad hadn't done some research and found Estes model rockets out of Penrose, CO.

I learned a lot while building, testing and launching those rockets. At one point I had a pretty good collection. No more accidents, though at one point I had a close call with a rocket that wasn't properly balanced for CG.

The car with the screw-eyes in the bottom on a cable came from my Dad - he did that in his fraternity house. He made a race car that was hollow in the tail. He powered it with a CO2 cartridge. He'd insert a CO2 cartridge, and run the car backwards into an ice pick that punctured the CO2 cartridge's seal, and the car would zip down the hallway with a loud woosh, smacking into a pillow at the far end of the hall. But he wasn't using anything flammable.

During my tour in the Marines, I was a radar systems and missile systems technician on F-4 Phantoms. So, I've spent a good bit of time with fast moving things that make plenty of noise.

It was not my goal to completely discourage you; but simply to warn you that what you were planning had some very nasty implications.

If you want to have a lot of fun with rockets in a safe sport, and learn a good bit at the same time, check out some of Estes' kits.
http://www.estesrockets.com/
They even have a rocket with a digital movie camera in it.

 

HI am interested in learning how to create a radio activated ignition system for a rocket powered radio controlled car.

Sgt Wookie offers sound advice: "Don't. Or at least put it on a real good leash."

it was $100 and thus over budget, so I stole it

Please know the official stance of the All About Circuits website is opposed to this action. We do not endorse or condone theft. Obviously, we can't report you, since we don't have your identity. But we are opposed to such criminal action.

will I be able to do this under budget (budget = $5)?

I see no way of making this happen by radio for less than an additional $15. Of course, if you run wire-guided, you won't need a second transmitter or receiver.

 

I suggest you not to build something just to prove your friends wrong. Do the things out of curiosity and you will be better of.
You can check to www.allelectronics.com they have a lot of cheap surplus parts.
I saw on AAC a similar thread to this one for a rockets remote controlled helicopter it was dated 2004. A moderator deleted it on the assumption that it could be use by Iraquis to target US trops. While it may sound silly there is no way to know for certain. Even I donot support US trops invasion of Iraq. I think it is always wrong to work or do something designed to kill people. We should start by ourselfs and the rest will follow.

 

use something soft and non-flammable to cushion the car to a stop at the far end of the run. A bunch of Ziplock bags filled 2/3 with water should make an effective brake

A net with fishing line/reel to brake the "flying" object works too