# Remote control lauch system??

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#### Rocketman 13

##### Well-Known Member
I looked around here a bit and I was wondering if there is anybody else who has made a wireless launch.I have made my own that is in a little box and I cut a wire and put it against the servo in the box and then when I pushed up the throttle button it would conect to the other wire and lift off! Rocketman 13

#### Justy

##### Well-Known Member
This is a good idea, with one minor and one major problem.

The minor problem is that the system probably doesn't pass the "safety key" requirement from the model rocketry code. Pfft. Who cares? You know better than to push the button (er, stick) when it's not safe.

The major problem is that such a system is very open to stray signals. If little Jimmy down the street fires up the Radio Shack hovercraft he got from Santa... or if the ham radio operator across town turns on his old tube radio, forgets to hook up his dummy load, and adjusts his radio while it's still connected to the antenna... or if you're anywhere near the house of a computer geek who works with really old Apple III's with chronic cooling problems and found that the computer worked better when I took the lid off so I never bothered to put it back on, but consequently it's not RF shielded anymore... then your launch system may be triggered at a bad time. Like, say, just after you've hooked everything up and you're walking away to a safe distance.

The only way a wireless launch system could be really safe would be if it had to recognize a coded signal. It wouldn't have to be elaborate, just something to minimize the chance that a stray signal would set it off. This wouldn't be easy to hack together, though. Also, not cheap. If I were going to do it, I'd use a pair of "BASIC Stamp" microcontrollers with radio links. When I push a button on the remote, the remote would send "arm it!" (no, really, I'd have it send text through the wireless modem link, a-r-m-_-i-t-!), and when I press the second button, it would send "make rocket go now". The computer at the pad end would trigger the launch once it recieved the first phrase, and the second phrase no more than 20 seconds later. Use the two-way radio modules, and it can even radio back your continuity checks etc. So you're looking at $100 or more for a BASIC Stamp starter set (gives you one Stamp and the stuff you need to program it with),$30 for the second Stamp, $100 to$200 for the radio linkage, plus the relays and stuff to actually make it do real work.

There are pro-grade radio control units for model cars/aircraft/boats etc. that have a digital encoding system to make sure that nobody else can mess with your signal, but last time I looked at those, BASIC Stamps looked cheap by comparison.

On the other hand, a 75' spool of 2-conductor speaker wire costs well under \$10 at Rat Shack, and aside from atomic bombs and other horrible things which would make misfiring rockets the least of your worries, there isn't much in the way of radio interference that will set off your rocket at the wrong time.

#### Rocketman 13

##### Well-Known Member
Hey Justy that sounds very cool I want one were can yuo find them? Thanks Rocketman 13