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My rocket does a 180 turn, any ideas why?

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Joppe

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So, I am a total newbie when it comes to rockets just to make that clear. But it just so happens that I got bored a sunday afternoon and decided to scratchbuild my very own paper rocket. I always like to do things myself, so thats why I did not just buy a kit at the hobbystore so you know.
But lets get to the point.. It was time to launch, so I drove to a nearby field, walked 100M to the middle through 50cm of wet snow and set up my platform and rocket. I lit the fuse and stumbled away hoping to see my beautiful construction go up, up and away. But, no... It went about 3M into the air, did a 180 turn and flew into the ground and went on to skid on the snow quite a distance before the motor burned out.:confused2: And the story repeats itself three times over, quite disappointing, but not unexpected.
So I am just wondering if anybody can give me some pointers as to why this happens, and what I could try to correct it. Any other reason than being homebuilt on a sunday will do.
The motor is also made on my workbench, 22MM ID with a 6MM nozzle, about 10cm long. Im adding the rocksim file I made, so if anybody cares to take a look at it, be my guest. Even try the construction on your own if you want to, to see if you get the results I did.

If anybody is wondering about the rockets name, its translation would be "The faller", since thats just what it kind of did, it fell over in the air and does not have a parachute.:blush:

Any help at all is much appreciated, thanks.

View attachment Ramlern1.rkt
 

shreadvector

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Your home-made motor either had a nozzle defect and had vectored thrust or your rocket was unstable.

We do not discuss making our own motors on this forum.

Stability is covered by many, many technical reports and books. Let's see if Estes ever restored their stability report on their website, if not I'll find other good links.

Look at the "Sticky Thread" at the top of this forum and review many of the linked documents. This one is very good:

Centuri Design Manual:
http://www.spacemodeling.org/JimZ/manuals/cmrdm.pdf
 

Joppe

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Thank you very much the reply and link. That cleared up a few things for me. I am, at least for now, pretty certain its an issue with instability. After abit of reading I'm thinking that I should add some noseweight, since the relation between CP and CG seems to be just plain wrong in terms of promoting stability. If that doesnt help(with my luck it probably makes it worse..) I'll keep on reading, asking and trying until it works. Anyway, thanks for the help so far! :)
 

Larry Curcio

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So, I am a total newbie when it comes to rockets just to make that clear. But it just so happens that I got bored a sunday afternoon and decided to scratchbuild my very own paper rocket. I always like to do things myself, so thats why I did not just buy a kit at the hobbystore so you know.
But lets get to the point.. It was time to launch, so I drove to a nearby field, walked 100M to the middle through 50cm of wet snow and set up my platform and rocket. I lit the fuse and stumbled away hoping to see my beautiful construction go up, up and away. But, no... It went about 3M into the air, did a 180 turn and flew into the ground and went on to skid on the snow quite a distance before the motor burned out.:confused2: And the story repeats itself three times over, quite disappointing, but not unexpected.
So I am just wondering if anybody can give me some pointers as to why this happens, and what I could try to correct it. Any other reason than being homebuilt on a sunday will do.
The motor is also made on my workbench, 22MM ID with a 6MM nozzle, about 10cm long. Im adding the rocksim file I made, so if anybody cares to take a look at it, be my guest. Even try the construction on your own if you want to, to see if you get the results I did.

If anybody is wondering about the rockets name, its translation would be "The faller", since thats just what it kind of did, it fell over in the air and does not have a parachute.:blush:

Any help at all is much appreciated, thanks.
Dollars to doughnuts, at least half of it is low thrust. Otherwise the thing would not have clung to the ground three times. All directions yes. Land shark? I doubt it.
 

SpaceAXEplorer

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Hi Joppe...

I've Looked over your Roc-Sim file.
May I please ask;
What type of material(s) did you use in the construction, and how did you construct it?

Tak!

Eric:)
 
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Joppe

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Hi Spaceaxe!

The body tube is made of brown-paper, rolled on a wooden dowel 29MM in diameter and bonded with carpenters wood-glue. The tube is 317MM long and 32MM OD when finished.

The nose-cone is made of 165g\m2 paper, rolled in one piece to make a simple cone shape, glued together, and trimmed with scissors to match the diameter of the body tube(should be 90MM long after trimming, and smeared with woodglue on the inside for extra strength), then glued directly to the top of body tube and left to dry abit. When dry the dowel used to roll the BT is inserted again all the way up to the nose-cone, then cut off the BT 20MM from the top so you get one piece with the nose-cone and 20MMM of body tube, it was done this way so it will be possible to fit in a recovery system later. A round piece of wood, 40MM long and the same diameter as the dowel used to roll the BT(I just cut a piece from that dowel) is then inserted 20MM and glued to the nose-cone assembly(the wood piece doesnt appear in the rocksim file, add weight to the nosecone before gluing the piece to it, wood was used for strength of the structure). About 30 grams of airrifle pellets was used to achieve acceptible theoretical stability, havent gotten a chance to physically test it properly yet though.

And the fins are made from cardboard pizza-box 0,5MM thick laminated in two pieces(Pizza grandiosa if you ever had it..:)), they were left to dry under a book & a brick so they would be straight when dry, I also had to iron them though since they still came out abit warped.

The engine block is made from plain copy paper and glued\inserted 100MM into the bodytube.
And the launch lugs are also made from plain copypaper, they are made to be a very loose fit around a 8MM stick thats intended to support plants, I found it to be a great launch rod as well..:D To make the lugs I rolled a good strip of aluminium foil around the "plantstick", and then rolled the lug paper piece around that to get the loose fit required.
The glue used for every part of the rocket was regular carpenters wood-glue, squirt abit of it on the part to be glued and use a damp paintbrush to spread out on a large an area as possible for an even bond and good strengt, then roll the piece together as straight as possible. Keep a bowl\cup of water nearby to keep the paintbrush in when not using it so it doesnt get ruined.
Thats about it, a very simple design and build.

If you want to try and build one use a recovery system of your choice, I really dont have a clue if it should have a parachute or a streamer.
I weighed the other day without a motor, and it was about 160grams. So I'm thinking of making a lighter version of it soon. It was initially built so it wouldnt fall apart after flying once, and its very sturdy the way I built this first draft.

I also dont have any measures for the materials used, except for the finished rocket since this was an improvised sunday-build. If you have a good set of calipers and rulers it shouldnt be a problem making this rocket anyway using the measurements found in this post and the rocksim file. To get the measurements for the fins just hit the edit button in the rocksim file and they should come up in Metric so you can easily make template. All the measurements of the rocket found in the rocksim file are accurate.
If you by any chance find this rocket to fly well, then feel free to make a version of it with your own choice of materials to stick on your website if you want to.

Joakim:)
 
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