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Stabilizing rocket without fins


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#1 Pretty green flames

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Posted 21 March 2005 - 05:02 PM

I'm building a replica of a german nebelwerfer (just for the fun of it), and if i'm not mistaken those rockets didn+t have any fins and they managed to fly pretty much straight.

How can this be acheeved.

Any help is welcome :)

Edit: Spelling edited :)

Edited by Pretty green flames, 21 March 2005 - 05:12 PM.


#2 BigG

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Posted 21 March 2005 - 05:13 PM

I'm building a replica of a german nebelwerfer (just for the fun of it), and if i'm not mistaken those rockets didn+t have any fins and they managed to fly pretty much straight.

How can this be acheeved.

Any hel is welcome :)

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Don't know - the two general methoods are fin or spin - unless they have a guidness system - but that's a different beast altogether.

#3 Pretty green flames

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Posted 21 March 2005 - 05:17 PM

I'd just like them to fly straight,

Any method is acceptable.

I already had a few missfires and it wasn't pretty.

Would the lenght of the entire motor stabilize it somehow.

#4 Andrew

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Posted 21 March 2005 - 05:22 PM

The German nebelwerfer rockets were fuelled by BP. Strangely the warhead was at he rear of the missile. The propellant was as the front of the rocket. As the propellant burned, the exhaust was sent down 26 pipes, with a cone nozzle on the end. These pipes were of coarse, in a slightly spiral configuration. This gave a very effective thrust and twisting moment. The resultant spin, stabilised the rocket in it's ballistic flight. I'm not sure if the pipes were down the middle or wrapped round the warhead. I think the latter is true and they were just inside the outer casing.

#5 Andrew

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Posted 21 March 2005 - 05:26 PM

I'd just like them to fly straight,

Any method is acceptable.

I already had a few missfires and it wasn't pretty.

Would the lenght of the entire motor stabilize it somehow.

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They were also launched out of smooth bore tubes.

Having 26 tubes seems a little extreme. You could simplify it by having a single large bore tube down the middle, and have a twisted vein afixed to the inside. This would give the same effect.

#6 Pretty green flames

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Posted 22 March 2005 - 07:58 AM

Ok so i thought about it again and i have come to the conclusion that the head can stick out of the tube. :)

What about if i used fins on the nose of the rocket. Would this work

#7 Andrew

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Posted 22 March 2005 - 11:57 AM

What about if i used fins on the nose of the rocket. Would this work

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Fins at the nose, in fact anywhere in front of the centre of thrust, will NOT stabilise a rocket. The only way to use fins in this way is to have an active control system. This will require a processor of some description and a few gyroscopes. If you were going to go tho these lengths then you would probably want to build a directional thrust nozzel instead. Fins also need speed to work effectively. :(

What scale are you building on, and what are you building it out of? If it is large enough to not be fiddley, you could spin stabilise it, there are many methods to achieve this. There are different methods for different sizes and types of rocket. :)

A little more information on size, construction, where the propellant is going to to be housed (nose or tail end) etc. will help anyone to suggest a good solution. :)

#8 Pretty green flames

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Posted 22 March 2005 - 06:23 PM

Well firstly this is going to be done on a small scale

with home made rocket motors with an ID of 16mm and lenght of 100mm

Nozzle will be drilled with a 4mm drill becouse i have no toolling (yet)
The propelant will be at the tail of the rocket with Davis's Cocoa powder I which i find is very good as a propelant

Also could you please describe spin stabilizing it (I know about stinger rockets but is there some other way)



Also i asked my dad about this also and he suggests using fins which would be rolled onto the rocket which would then spred out when the rocket left the tube.
I'm interested in your opinion

#9 Creepin_pyro

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Posted 23 March 2005 - 02:47 PM

This may be slightly off topic, but I've always wondered how parachute flare rockets manage to fly straight...

There's no stick stabilisation, and no spin/fin system as far as I can tell. Anyone care to enlighten me?

#10 seymour

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Posted 24 March 2005 - 07:29 AM

Dam good point!

All this talk about finnless, stickless, rockets that arn't stingers is making me timid. I will just carefuly trace my footsteps back to the world of sticks...
The monkey leaped off it's sunny perch and flew off into the night sky.

#11 alany

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Posted 24 March 2005 - 07:40 AM

The same way stickless whistling missiles work. They are nose-heavy, the tube itself is like a stick or fins, the centre of pressure is behind the center of mass by a few caliber so they are nice and stable.

Some use tube fins too, which is easy to implement, just cut a slice of thin-walled tube and use a few pieces of bamboo of hang it off the back, or just wrap a turn of cardboard around a few sticks tapped to the side of the motor tube. Easiest missile ever really, I should try making some of my bottle rockets like that.

Edit: typo

Edited by alany, 24 March 2005 - 07:41 AM.





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