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Posted: Thu Dec 27, 2007 8:56 pm
by VH_man
comon you guys!!!!!!! take blowgun dart and fire it straight up........ notice how it remains stable????

how is a blowgun dart different from a rocket? in my eyes, this is actually SAFER than launching from a launch rod. the reason thats there is so that the rocket has time to get moving fast enough for the rocket to gain stability before it takes off.

if anyone has rocksim, you can experiment with launch rod lengths. if you set it at 0, the rocket goes ALL OVER for a few secodns then straightens out when it hits the speed where its fins do something in the forms of stability.

Posted: Thu Dec 27, 2007 9:08 pm
by BigGrib
TurboSuper wrote:I believe most storebought rockets are designed so that the change in weight from the burning engine doesn't offset the center of gravity to the point where the rocket changes course.

I read a technical manual on model rocketry (put out my Estes), which outlined how to test a rocket for stability (tie a string to the nose cone and swing it around), and to add bits of clay if it needs balancing. I'll assume their premade ones come pre-balanced.

I once just got a really small rocket and put a C6-6 engine inside of it...thing flew into a cloud.
Umm i know that the last model rocket i bought which was about 3 years ago and it came with a little deal of clay to go in the nose cone to balance the deal out.

As far as timing the ignitor to go off after the rocket leaves the barrel, how bout just a little switch that engages on the way out of the barrel like a spring switch or something with all the ignition system, ie a AA battery a micro timer and a switch, housed inside the rocket itself.

I also like the idea of a tiny drogue chute to keep the rocket flying straight, and having it strung right behing the engine so that upon ignition the drogue is released.

the only thing i think might need attention is the stability of the rocket in the barrel, maybe used two sets if fins to keep the rocket centered and then also a sabot for launching the rocket. ok thats all my thought on how to make it work safely

Posted: Thu Dec 27, 2007 9:21 pm
by sandman
@ TurboSuper you are correct about the store bought rockets they are designed overstable so that payloads can be added and the center of gravity still be ahead of the center of pressure. But, on the stability you dont tie a string to the nose cone you tie a string around the center of gravity and swing it around your head and add weights till it stops wobbling.

EDIT: OMG, i thought i was like the only person in the world with rocksim, lol, now i know there are others out there

Posted: Thu Dec 27, 2007 9:37 pm
by VH_man
hahaha sandman i LOVE my rocksim........

i screw around with that when im bored with the really big engines and dream................

Posted: Thu Dec 27, 2007 10:12 pm
by sandman
lol, i <3 rocksim too, but i do wish it could model fins on fins and external engines but ill take what i can get.

it be building whats below now, but i discovered spudding and i dont have the monies for it anymore :(

Posted: Fri Dec 28, 2007 8:40 am
by ralphd
It's been awhile since I messed with model rockets. I started with Century then Estes. I still have a soft spot for them but it's dead here in NE Ohio. Sure, a few scout troops play with them for their merit badges but not like when I was younger. The string test is important but you must have a launching rod to stabilize the rocket at launch. Believe me, this I know for sure. I used to try to launch different ways and with different payloads...remember the 110 camera.

Posted: Fri Dec 28, 2007 4:13 pm
by sandman
ralphd wrote:but it's dead here in NE Ohio.
i will never let it die, so its still alive

Posted: Wed Jan 02, 2008 12:56 am
by Bubba05
Yeah i think thats the bloke? But this one gave a licked a 12 gage.

Bubba

Posted: Wed Jan 02, 2008 1:07 am
by Pilgrimman
@ Sandman

I've got it too. It's for a physics project. Guess what the body's made of? That's right! PVC! :D

Posted: Wed Jan 02, 2008 10:43 am
by sandman
woot, more believers
it looks like we could open a model rocket forum, lol

Posted: Fri Jan 18, 2008 12:28 am
by OuchProgramme
blind909 wrote:because they go alot higher and could do some damage when it comes down from that hight.
Actually there are such rockets as parachute, or "break nose" rockets.
The nose of the rocket blows off, or the body snaps in half. When the body breaks, there's more air resistance, slowing the fall greatly. Also, the nose wouldn't be faced downward...

Posted: Fri Jan 18, 2008 12:12 pm
by jimmy101
TurboSuper wrote:I read a technical manual on model rocketry (put out my Estes), which outlined how to test a rocket for stability (tie a string to the nose cone and swing it around), and to add bits of clay if it needs balancing. I'll assume their premade ones come pre-balanced.
Actually, I think you remember incorrectly. The proper technique is to find the front to back center of mass of the rocket and tie the string there. Then swing it around. If the rocket is aerodynamically stable it will fly stably, if it is unstable it'll tumble.

This works with any projectile that is meant to fly subsonic. It works with bullets, water rockets, model air planes etc.

Posted: Fri Jan 18, 2008 3:55 pm
by bigwick
no its legal. have funn

Posted: Sat Jan 19, 2008 5:25 am
by Davidvaini
I say let it slide. We could be a Nazi about the rules, but its not like he is launching the rocket at someone. and besides its a model rocket for goodness sake.

If however you were firing a rocket that explodes on impact that could cause a lot of damage and you were misusing it then I would say gtfo, but currently I would love to see it :D