PVC Rocketry???

[Jared Haehnel]

Thanks for the tip. I never imagine this thread would carry this long you guys have been awe some (and girls if there are any 8) )

[koolaidman]

ive fired rockets out of pvc before. I think they were B's maybe they fit into 3/4' pvc i epoxied fins onto them. The fins were the plastic inside of a keyboard, they fit into the tube, but retained their shape after they exited the barrel. This will save you from building a heavy projectile or a sabot. I did this twice once was in the dark, so i dunno where it went. The other one did not leave the barrel, its thrust shot out of the back for a good ten seconds till i remembered that i had filled the nosecone with flour and it blew up all over me.
Anyways i say keep the ignition simple i agree with the idea of combining the solenoid circuit with the ignition coil. Rc would be expensive, you would have to hit a button, my guess would be that the rocket would already be long gone, and you would probably only get one shot at it. a switch would be ok but it would be heavy as well and you would have to arm it after the rocket was in the tube and the switch was pressed. a cannon fuse might work, for a combustion you mean?

[SNDM]

So how will this be lit?
While its in the barrel?

As you say, your fuse burns at around 1000 degrees, Im not sure PVC is solid at those temperatures.
Either that or you fire, quickly drop your spudgun, and run after your rocket with a lighter trying to light it.
Interesting, madmittedly, but unrealistic.

You would have to construct your barrel with iron, steel (I dont know the melting point of copper)

Although the fuse will only burn for a few seconds, and probaly wont have a huge effect on the overall temperature of the barrel, its worth having the safety.

Another thing is wether the fuse will be blown out by:

A: The compressed air pushing it.
B The wind as it travels at high speed through the air.

A faulty design could make the air eddy around the back of the rocket and put out your fuse.

Another (yup, better believe it) thing is how your rocket will look like when its smacked into a wall.

I recommend a cardboard rocket, with foam willing it, and in that foam you could put your electrics.
(If anyone has some aerogel lying around, that would probably work fine.)

There you go, some pointers, I too have all the equipment needed to do this, loadsa rocket motors, rocket supplies etc, so I may think about this if given a foolproof design.

[ammosmoke]

Well like I said, a RC car receiver is about $20 on ebay WITH a remote. But I did consider the possibility of the fuse going out. I don't think it is likely. It is used all the time for artillery shells, which shoot out of the mortars at a fairly high velocity. And, the silly fuse flies at least 150fps all by itself. The fuse would only be in direct contact with the pvc for about 1/4 of a second. I have actually put this fuse through pvc, and it did melt it a little, although you could probably solve this mostly by wrapping the fuse in tinfoil where it went through. Or, using steel or copper pipe. BTW, Mapp gas torches burn at 1500 plus degrees Farenheight, so I doubt this will melt it lol.

EDIT: However, there is a chance that it will blow out, so testing is in order. I say, try it with a string of firecrackers in the pvc body. Place a rimmed endplug on the bottom, and a cone on top. (The rim so it doesn't get shoved into the rocket. Have a hole through the endplug, and well you can figure out the rest. Oh yeah, and DON'T glue the endplug. You want to hear those crackers..

EDITEDIT: Oh yeah, and you would light, then fire when the fuse went in, as I already said. Read my above post more closely.

[grumpy]

why not just use a clothes pin? i will try to explain, take a wooden clothes pin and in the end that closes together you drill a small hole in each side that you will put two small bolts into, these are your contac points that when you atach the wires from the batteries and they make contac will fire the rocket. then make up the battery pack with wires atached to the clothes pin. you will then need to mark and drill a small hole in the side of your rocket this will be for a pin to slide into and push the clothes pin open so it does not make a connection, the pin will be held in by the launcher untill it is fired. once fired the pin pops out as the rocket leaves the barrel ignighting the rocket. everything should fit into the rocket, hope i explained it right, but maybe you get the basic idea.

[SNDM]

not quite, can you rustle up something in paint?

I think that best option for in-barrel ignition is a metal barrel, or high temp plastic, with, if you want, a PVC pipe over that to insulate it.

And as for wrapping fuses in tinfoil, dont bother.
Remember match rockets?
http://www.matchrockets.com/fire/mr.html
#You do now.

Anyway, the match igniting would often burn right through aluminium foil easily. I dont think the tinfoil would prove anything near a match for the fuse, especially if its artillery grade fuse, which is pretty furious apparently.

Maybe to ease loacting of the rocket, you could have a tiny balloon fuill of paintball paint on the front of the rocket, so it goes splat.

[Jared Haehnel]

I would preffer the rocket to ignite out side of the barrel... A long fuse would accomplish that very nicely I don't believe that the heat produced by the fuse will be sufficient to endanger the barrel even if it is PVC.

How ever if the rocket ignited inside the barrel then we could have a problem...

I've played with matches before... and aluminum would not work but a small diameter brass pipe or even a strip of tin where the fuse might come in contact with the barrel would probably solve that problem.

If you could post a picture of what you have in mind Grumpy that would be great...its a bit hard to visualize.

I also wondered if the blast of air would put the fuse out probably could enclose it into some thing to make sure.

How'd the rockets look at night?

[ammosmoke]

I have lit it inside aluminum foil before, and it did contain it, however it turned into a sort of ash.

They do look pretty cool at night, have a nice trail of sparks. I have lit several skyrockets inside pvc tubes, its really no problem, aside from the ash buildup. Its simply too brief to do anything harmful.

EDIT: I would imagine that it is pretty hard to put the fuse out, as it can survive the firing blast from a mortar. But the possibility is still there. It is 1/8" fuse, not 1/4" which is simply gigantic, and 1/4" probably would melt the side of the barrel.

[Jared Haehnel]

Then there is no worries... 8)

[dewey-1]

--

[Jared Haehnel]

Now that is awesome, well drawn, and well thought out... and very feasible... any one guess how far that might go if luanched at 600fps from a two inch barrel?

I'm predicting that should way around a pound for the first rocket and closer to a pound and half for the nerf vortex one... agian I could be off by alot so correct me if I'm wrong...

Any one know the stats on a C6 series engine?Burn time, thrust (in pounds) wieght...

I am assuming the previous engine ignites the second one...

[dewey-1]

--

[Jared Haehnel]

I stand corrected... I knew the engines would wieght a few ounces however the body them selves I was figuring on a bit more... mianly becuase I wasn't sure your typical estes rocket body, balsa and cardboard, as you mention could stand up to much abuse.

I figure my spud guns on DDGT to luanch 400gr projectiles thats where the one pound came from... with the reduction in wieght I can get a higher fps... longer distance.

Total of 75 grams of thrust...doesn't leave much to fiddle around with...if my rocket wieghed a pound I doubt it would even get off the ground

I'm going to have to check out my local hobby shop and see if I can't pick up a kit and biuld one of these suckers just to play around with it some more before I attempt it... I'll be using my new cannon for it once I get everything biult and tested

Thanks

[ammosmoke]

At that fast of a speed you may want to test fire with something that evidences it is working. Something cheaper than a rocket motor.

EDIT: You could always get an E motor instead of a C. WAAAAAY more thrust. Would push a rocket that is a pound probably 400 feet.

[jackssmirkingrevenge]

Nice designs dewey, that's pretty much how I had pictured them