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Egg-O-Naut C

Posted: June 24th, 2008, 1:40 pm
by andrewwski
Looking at the draft rules, I really hope they increase the time from 5 minutes to 10 minutes or so. 5 minutes is not enough to launch two rockets, especially counting the time it takes to pressurize the rocket and the time aloft, plus the fact that they expect you to retrieve it immediately. With winds, I'm expecting it to travel downrange at least a few hundred feet.

Anyone messed around with bottle rockets extensively? I used to launch bottles by sticking tire valve stems in them and pressurizing, but I'll need to make a decent launcher with a clamp of some sort (probably using the bottle's flange) and a pressure gauge.

Plus I'm going to have to figure out recovery - there's got to be a way to have just a padded capsule detach and parachute down.

Re: Egg-O-Naut

Posted: June 24th, 2008, 2:58 pm
by sachleen
the good thing for us is that one of the chem/physics teachers does A LOT of rockets with his class so instead of figuring out what sucks I get to use their data and work from there. He has a cool launching system.. first you would take a ring stand and take the 'stand' off so its just a rod and put it into the ground, slide the rocket on and at the bottom of the rocket, put the launcher under the rocket. You would put a cork into the bottle and from the cork is a tube leading to the pump. so once you finish pumping the air, pull a string and the cork comes out and rocket goes up. It would be fairly simple, don't even need any sort of launch pad type thing, just dig a rod into the ground and put a cork in the bottle.

the rocket will go up, and it has to come down, so I was reading some stuff, and you could have the bottom half of a soda bottle on top of the rocket and that part carries the egg and separates from the rest with the parachute coming out of it too. the way I imagine this is the top half of the rocket, the part containg the egg would turn with the open end facing up when its falling and the egg would land safely.

This event will be really really fun to watch and do! cant wait :D :D

Re: Egg-O-Naut

Posted: June 24th, 2008, 3:30 pm
by willhockey16
The two interesting things to see in the official rules are whether they allow parachutes and whether it'll be an on-site building event.

Re: Egg-O-Naut

Posted: June 24th, 2008, 4:06 pm
by sachleen
I hope they do, its more fun that way :) Also, i REALLY REALLY hope its not on-site, JYC is enough...

Re: Egg-O-Naut

Posted: June 24th, 2008, 6:00 pm
by andrewwski
Draft rules don't show it as being on site (lets hope it stays that way).

Parachutes make it a lot more fun.

There would still need to be some kind of release system, to separate the section with the egg from the rest of the rocket. It would some how need to be mechanically triggered when the rocket it as its highest point...

Either that, or you could use gravity for a release...if the rocket tips nose-down on its way down, a section falls off, but to me that seems a bit unreliable.

tehkubix...I don't know if I quite can picture the launching system you're describing. Is the rod going to be fed through a launch lug on the side, or into the bottle itself? What then keeps the bottle anchored down onto the cork other than friction between the two? Or does the air pressure from the bottle not exceed that? I've seen some systems where the flange around the neck of the bottle is used to anchor it down.

I know in the past I've used tire valve stems to insert into the bottle, but the bottle would blow off at about 85 psi. Saying this is only 60 psi, that approach may work.

I guess I'll work on some sort of launcher this summer...definitely with a 12v battery and air compressor (too lazy to pump).

Re: Egg-O-Naut

Posted: June 24th, 2008, 7:08 pm
by sachleen
He also have one where metal thingies are used to hold it down and when you pull the string, the metal parts flip sideways and let go, that may work better..

Re: Egg-O-Naut

Posted: June 24th, 2008, 10:07 pm
by gh
He also have one where metal thingies are used to hold it down and when you pull the string, the metal parts flip sideways and let go, that may work better..
Yeah, I'm pretty sure your other system requires a lug that slides onto the guide track. This is the one that they usually use (or variations thereof). I'm probably going to invest in a launching system with a tripod this year though. Launching stuff from the grass by sticking things into it gets really messy. If the grass is frozen over, well... it sucks to be me. :P

It looks like parachutes are in. Two liter bottles are not.

Hmm, thinking out loud: if you use really thin CA on the bottle, it would cause no visible damage, and you'd be able to pass it off as silicone. Then again, I don't think thin CA's solvents stay long enough to cause damage in the first place...

(these emoticons are really freaky)

Re: Egg-O-Naut

Posted: June 25th, 2008, 8:30 am
by andrewwski
It'd be nice if the rules give an overview of how the launcher will look, so that there are no surprises on competition day.

So it sounds like they actually use a launch lug with a rod inserted through it? That at least will help it stay straight.

A thin CA won't alter the structural integrity enough, but I'd avoid it to prevent being DQ'ed. A hot glue would be perfectly safe, but again, it's prohibited. There's no way your average hot glue gun will melt the bottle, especially without touching it directly.

I wonder about epoxies. Are these considered super glues? They cure in a similar way, but it doesn't specifically prohibit them. They wouldn't "bubble" or "thin" the bottle though...neither would a thin CA or super glue either...

I've pressurized 24 oz bottles well up to 100 psi without them bursting, 60 really isn't that much of a concern...

Anyone know of good silicone adhesives though?

Re: Egg-O-Naut

Posted: June 28th, 2008, 4:03 pm
by rocketman1555
i don't know any silicone adhesives, i usually use polyeruthane

the launcher will probably vary based on where u r, each area usually has a different launcher, i'm sure if u ask the event coordinator they will tell u

and lots of the rules they make r just in case, though i don't understand y they ban hot glue, but i wouldn't use it, its not that reliable anyway

and back to the 1st post, 5 minutes should be more than enough, u set up both of them, shoot them off, then pick them up after both r launched, and if u have to pick them up right after shooting, u have one person pick them up, while the other sets up the next rocket to launch

i was really hoping for bottle rockets, but this should be fun, though i hope they don't allow parachutes, it makes the event a lot more fun, and a little more difficult

Re: Egg-O-Naut

Posted: June 28th, 2008, 7:34 pm
by andrewwski
No way. First, that would mean there would have to be two launchers, which is probably not the case.

Even if there was one launcher and you could do it as you said, it's nicer to have two pairs of eyes watching it be set person to observe the other and check for errors.

However, 5 minutes is not enough to retrieve the rockets and do everything else. Around here, regionals are in February, when there's at least 2 feet of snow on the ground. Now I don't know where you're from, but if you've ever tried walking in 2 feet of snow, you know it isn't easy. You can only move as fast as a slow to moderate walk, and that is quite exhilirating in itself. And it's not uncommon to have as much as three or more feet of snow, especially if it has recently snowed. If the rocket blows downrange a few hundred yards, it would take the entire 5 minutes to retireve that rocket.

10 minutes seems more like a fair time. Things NEVER go well when you're rushed.