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#1 pritch

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Posted 19 June 2004 - 03:24 PM

I just made an end burning rocket with the specifications

25mm id, 27 mm od, 11 cm long with a nozzle opening of 4 mm.
My case is thin but rock solid. I used an epoxy glue with hardner. I could not squeeze it with my fingers.
I used my super fast willow pulverone + 7% fe/ti.

I am pretty sure it's fine to use the pulverone because it is just basically granulated to make ramming cleaner. So now it's rammed it should be the same speed as if it hadn't been made into pulverone.

Dan williams made a 6 pound end burning rocket using his fastest willow charcoal. So I think I should be ok.

Has anybody else made rockets of a similar size? Got any information for me on how it performed?

I do have a feeling my case is going to burn away in flight. I think as long as it is at a decent height then it will just look good :)

I just weighed it and it came to 85.5 grams. I only used around 20 grams of bp I think. I hope I havent made my clay plugs too big. I did make them about an inch thick for both the nozzle and the end plug.

Edited by pritch, 19 June 2004 - 04:24 PM.


#2 Mortartube

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Posted 19 June 2004 - 04:56 PM

My personal (and sceptical) prediction, is that you've just made a big banger. If I am proven wrong I apologise, but Pulverone will not crush down to the cosistency of meal when being rammed. BTW, how many increments did you use? 4mm sounds a tad small as a choke to me. Use a long fuse, as if it does explode, epoxy resin will be lethal when flying around.
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#3 pritch

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Posted 19 June 2004 - 11:03 PM

I had no fuse :( So i have had to hold off.

The epoxy is not a resin. It is epoxy glue and hardner from B and Q. If I am wrong and epoxy glue is also dangerous then please tell me and I will give it a bigger choke to guarantee no explosion.

Also I am fairly certain that people purposely add water and 5% dextrin or more to their meal and then corn it, just to make the ramming process cleaner. Unless you can only ram when it is still wet?

If this is all true then maybe I should give like a 7 mm nozzle and just use it as a fountain.

#4 Chaz

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Posted 19 June 2004 - 11:47 PM

4mm a tad small? I usually use 3.7mm and they never CATO, the other day I tried out 3mm and that worked beautifully. Inch thick nozzles seems waaay too much. I tried out a rocket once, it was 75g in total, and 30g without the payload. Didnt get off the ground, however it could have been because the stick was so long to balance it out that it got stuck in the tube because it was bending over a bit.

I reckon itll burn but not get off the ground. Up-side-down fountain.

#5 Matt

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Posted 20 June 2004 - 01:25 AM

Also I am fairly certain that people purposely add water and 5% dextrin or more to their meal and then corn it, just to make the ramming process cleaner.

No, not corning. That is called ricing, amongst others. Just moisten it (doesnt even really need a binder) and "grate" it through a screen. Gives you grainy propellant which wont shoot up out the sides of the rammer...

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Try to run! try to hide! Break on through to the other side!! YYYEEEAAAAOOHHHHHHHHAAAAHHHHHHHH

#6 pritch

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Posted 20 June 2004 - 12:26 PM

Well thanks for the info. Btw mortar tube I rammed one teaspoon at a time and gave it 7 hard hits with a 4 pound hammer. For the clay plugs I used a vice at the end to compress it at both ends. When I was hitting the hammer the end plug was falling to bits. I stuck a card plate over it and taped it up for the ramming process and it was fine after I had put it in the vice.

Also I think I might launch them tonight. Im going to make a fountain with my latest batch of meal.

#7 sasman

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Posted 20 June 2004 - 06:05 PM

Pritch Hope it works :) ..
make sure you post the video of your results..Dont Forget Dan williams said "The true secret to this project's success lies with the paper tube that is used for the motor casing."

#8 pritch

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Posted 21 June 2004 - 10:22 PM

Ok I just launched. I will consider this a successfull launch. Considering the total weight came to over 95 grams, including the heavy stick cause I ran out of proper lightweight dowel. I would not be suprised if the bit of wood I used came to more than 15-20 grams but I forgot to weight it.

Anyway here is the video.

http://members.lycos.....ig Bertha.MP4

Or http://members.lycos.....ig Bertha.WMV if you dont have quicktime.

Considering my clay plugs were over an inch each and I only added about 20 grams of fuel so most of the weight must have came from the clay. If I cut them in half, use a proper piece of lightweight dowel and use the same fuel then I think I will have made a really nice looking rocket :)

Edited by pritch, 21 June 2004 - 11:28 PM.


#9 pritch

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Posted 22 June 2004 - 04:03 PM

Ok I was just making an improved model of this with slightly less metal and regular size plugs. I was ramming and my 5 mm case split :(

Anyway. My case which was 5 mm thick and 10 cm long came to 17 grams. my end plug used 6 grams of clay and was 1 cm in thickness. Does this case sound heavy to you guys for its size?

#10 The_Djinn

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Posted 28 June 2004 - 09:39 AM

Pritch,

A tip I picked up from somewhere which I have seen on numourous other sites is to use a piece of PVC pipe that has been cut down its lengh and had a piece removed so that when the edges are pulled together the inside ID is the same as the outside ID of your tube. Plce the tube inside the PVC sleeve and use either pipe clamps or cable tyes all the way up and down the sleeve to hold it firmly. You will find that when ramming or using a press that your tubes will not buckle or split.

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#11 pritch

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Posted 28 June 2004 - 10:28 PM

Ah nice idea mate. I actually used one of those pvc tubes as my launch tube.

#12 Jerronimo

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Posted 29 June 2004 - 07:22 PM

how to make a sleeve

Here you go
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#13 pritch

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Posted 27 October 2004 - 05:59 PM

Big Berthas 2 is busy drying. I couldnt drill my nozzle clean so I used rock hard putty. The case with clay end plug weighs 15 grams. I'm predicting the nozzle plug weighs around 10 grams.

I started by loading a mix of approx 30 grams of my willow meal with 5% 60 micron aluminum powder and 5% fe-ti. I am hoping the aluminum will balance out the slowness of the fi ti and may even speed it up enough to explode in the air or give a big boost mid flight. This is the end of the rocket. The rocket then weighed in at 46 grams. I then started loading the actual propellant. 5 hour milled willow meal on its own. With the main propellant and the nozzle plug in place it weighed around 85-95 I forget. It has a 4 mm nozzle and core which goes in about one quarter the way of the propellant. I got a lot more fuel in this one then I did the last one which had a super thick case and nozzles. Also I will have a much lighter stick. The last one weighed around 20 grams I have discovererd.


It's either gonna cato or be spectacular. :D

#14 Loci

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Posted 28 October 2004 - 06:35 PM

I was passed this link jsut 5 mintues ago

http://www.videorock.../USS_Bakula.wmv

Impressive I thought :P

Will this be the big Bertha version 31 pritch?
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#15 Matt

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Posted 30 October 2004 - 02:28 AM

Holy freakin crap! that thing was crankin some pace!
I wouldnt mind seeing a video of it from the ground.
Try to run! try to hide! Break on through to the other side!! YYYEEEAAAAOOHHHHHHHHAAAAHHHHHHHH




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