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Posted: Sat May 26, 2007 12:24 am
by GinsuGuy585
Well first of all it would be launched from a pneumatic gun.

The whole idea is that instead of wasting a lot of energy moving the rocket from 0-45mph or so, the engine kicks in then and further accelerates the rocket. This could get it going fairly quickly.

I was thinking the same thing for an accelerometer switch, but it might not engage long enough for the motor to ignite. A photoresistor could do this. I am fairly experienced with electronics, and should be able to fine tune the ignition using a 555 and some J/K flip-flops. A photoresistor is also a lot easier to bench test than an accelerometer. To get the ignition to occur asap I could even put an LED into the side of the barrel (make it flush with the inner wall.)


The Reason for all this: I also think it would be the most awesome thing in the world to have a 'replica' stinger that launches, and is legal/non damaging. In the same way that I like watching air shows with $12+million death machines. All the looks with no danger. 8)

Posted: Sat May 26, 2007 6:51 am
by jrrdw
1 problem with ignition inside the launch tube is to much back pressure on the rocket motor causeing it to explode. I seen that happen once while liting my rockets up. Some dude brung his rocket to where i was useing mine and he built his motor mount above the fins about 4"s up into the rocket body, he used my launch pad and 3 seconds tops it exploded, rite at eye level. 1st time i've seen a grown man cry over a toy, funny. Any kind of added device to the rocket will throw the balance off causeing unstable flight, rocket gone wild! Talk to the guys over at www.SkyHighRockets.com , or go to the links page at www.cannonfuse.com and there is a rocket link to a guy who does water launches, he has good onboard ignition. Hope this helps. Here i dug this up for you, it's all about ignition systems for rockets.

Posted: Sat May 26, 2007 6:56 am
by Redcoat
i dont know alot about electronics but how about if you put a sought of flammable or electric conducting thin wire coming from the back of the rocket and have a second button/switch/trigger which sets it off after its left the barrel.It would be a quick press like a bam(2 secs) bam.

Posted: Sat May 26, 2007 8:05 am
by thrasmussen
GinsuGuy585 wrote:Well first of all it would be launched from a pneumatic gun.

The whole idea is that instead of wasting a lot of energy moving the rocket from 0-45mph or so, the engine kicks in then and further accelerates the rocket. This could get it going fairly quickly.

I was thinking the same thing for an accelerometer switch, but it might not engage long enough for the motor to ignite. A photoresistor could do this. I am fairly experienced with electronics, and should be able to fine tune the ignition using a 555 and some J/K flip-flops. A photoresistor is also a lot easier to bench test than an accelerometer. To get the ignition to occur asap I could even put an LED into the side of the barrel (make it flush with the inner wall.)


The Reason for all this: I also think it would be the most awesome thing in the world to have a 'replica' stinger that launches, and is legal/non damaging. In the same way that I like watching air shows with $12+million death machines. All the looks with no danger. 8)
You must think about the fact that it takes a pretty large capacity battery to set off a rocket. How are you going to fit that into a rocket body?

Posted: Sat May 26, 2007 8:25 am
by BC Pneumatics
Guys, why think so complex? Pull sting ignition is the way. Just make it light enough (and the cannon powerful enough) so it doesn't severely hinder the flight path :)

Posted: Sat May 26, 2007 8:34 am
by jrrdw
Maby a pull string hooked to a disposable camra flash set up attached to the firing end of the rocket motor. It would burn off fast, thus not interfearing with stabilty of flight. I think trying to push a second button wont work because of the speed it's going to have leaving the launcher??? You would need a new ignition evertime but i can picture it working well.

Posted: Sat May 26, 2007 10:15 am
by BC Pneumatics
I meant abandon electrical ignition all together.

Posted: Sat May 26, 2007 8:04 pm
by jrrdw
You mean like a stricker and match with a string fastened to the stricker? The motor would blow the burnt match head rite out, i've made match head fuse for launching rockets before. It worked about 90% of the time. Thats good thinking! Simple and sounds like it will work.

Posted: Sat May 26, 2007 8:30 pm
by iPaintball
I think he means something like this:

http://youtube.com/watch?v=aUFYwTY4DBk

Use a pull pin ignitor. I use them for my smoke bombs all the time. Just put some blackpowder primer in the rocket engine, stick a piece of quickmatch or a very short piece of Visco in the nozzle, and attach a match to your fuse with wire. Wrap a strip of a match striker pad around the mactch head and wrap wire around it. When the rocket is launched out, the striker pad will ignite the match which will then ignite the fuze.

Posted: Sat May 26, 2007 8:50 pm
by VH_man
just use double-stage rocket motors made by estes. the ejection charge is fitted not only with fast burning powder but also little flaming chunks that get up into the nozzle of the motor above it, igniting that motor....... it works for me............

Posted: Sat May 26, 2007 9:00 pm
by BC Pneumatics
VH, that ain't no fun.

Posted: Sat May 26, 2007 9:13 pm
by VH_man
yeah, i guess, but it works. i guess you could have a timed fuse or something from the end of the fuel (so it starts burning when the engines fuel runs out) and then when it burns up to a certain point it detonates an explosive charge that seperates the other part of the rocket and ignites the other engine......

you have to tell me youre firign this out of a shoulder mounted tube........

Posted: Sun May 27, 2007 8:08 am
by jrrdw
That is a awsome rocket launcher! I noticed something becureyour(sp) about it. 1st this question, Would the weight of the rocket motor make a visibly difference in speed?