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Blaf

BP Rocket

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Hello there

I know you waited some time for a new topic...so here you are.
I made a BP rocket engine from a cardboard tube of 18mm diameter, with bentonite clay nozzle. I made everything right...except I rammed granulated BP in pretty large increments...I should have done that in much smaller ones. The engine was then topped by cylindrical shell of little larger diameter filled by two types of stars - aluminum and charcoal based. A piece of pointed cork was acting like a rocket tip and a piece of barbecue stick played a stabilizer role. So, we have a nice business-like rocket. The evening was little wet, perfect for an experiment of unknown outcome. Which indeed happened so. The fuse was slower type of my own make, I lit it and retreated at safe distance. After it burned out a loud hissssss was heard and a low pich bang right after. You guess - we had a CATO situation here! The contents of a shell was blown out and the final effect resembled a decent star-mine. Here I should go back to ramming the propellant - it should definitely be done in small increments...larger ones leave too much space (air) between BP granules so that flame propagation is way quicker and engine explodes rather than thrusts. Small increments of BP followed by good, firm ramming - that's the recipe. I had a CATO....so what? Next one will be done much wiser and perhaps with little higher percentage of charcoal in BP.

Comments and suggestions are welcome as always!

Blaf

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Make sure you don't use real BP in rockets :) .

I use BBQ charcoal witch was milled with the other ingredients for a half hour and then wettened,

if the BP is still to fast then you can use more charcoal, i meself prefer to launch shells with a mortar then with rockets.

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Hello Exhile, glad to hear from you again!

You might be right - moistening the whole thing could be part of the solution. Another is to add more charcoal to the mixture. I'll surely try both and let you know. As for mortars, I still look for adequate plastic tubing with beefy sides to bring my mortars to life. We'll see....

Blaf

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Use HDPE 100, these tubes are used in high amounts as high pressure gas tubing, look next to the streets, black tubes with a yellow/red writing.

I use paper tubes for small shows because I don't have the money to buy 20 of these tubes.

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Good afternoon,

I always use a stainless steel tube to launch my shells.
And I still work with the same tube for 4 years now.

( excuse me for my bad english)

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At the same time with latest tourbillion, a small plastic BP rocket was made carrying a modest payload of microstars. Nothing special, plastic tube of some 7cm lenght, 10mm inner dia, bentonite end plug which later become a 3mm nozzle (drilling required). The propellant (newest batch of geranulated BP) was rammed in with appropriate wooden dowel. No spindle or core forming were used this time, just a plain flat ramming. Well, I used 2mm drill-bit and drilled a core of 15mm in the grain through the nozzle. After the propellant reached 1cm from the top I ended it up with a tissue paper rammed as well. A small passfire hole was drilled with 2mm drill-bit through paper plug all the way to BP propellant. Slow drill speed was used....you never know. The plastic tube was then topped by craft-paper tube 3cm in lenght with inner dia matching outher dia of the plastic tube. Inside you could see my granulated BP mixed with some pillbox stars made much earlier...nothing much, just to spice it a bit. The rocket was then equipped with two wooden stabilizers opposing each other. They were pretty short and I wanted to avoid erratic flight. And there I was, lighting my device in front of my nieces hungry eyes. This time we had a nice and quick take off, loud plain hiss and inevitably PLOP and spread of stars some 30m above the ground. The stars were too small to make an impressive display but it worked!!!
Conclusion - it's possible.

Blaf

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Hey Blaf,

I have to say, your rocket is beautifull !! Has it allready flown?
But why do you use 2 sticks instead of one, and what kind of a glue do you use? Hot glue?
(excuse me for my bad english)
greetings,

Nick

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Hi Nick!

For details of constructon read my previous post. But again, yes you're right - that's hot-melt glue and why two sticks - because sticks I had were rather short and I used two of them for better stabilization.

Thanks for your nice opinion!

Blaf

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Yesterday I made another BP engine, but this time much bigger. It's made of convolutely wound paper, 3mm thick with inner dia of some 15mm...if not even more. You maybe don't see it but nozzle hole is slightly out of center so that I should use longer stick to stabilize its flight.
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Second image shows the Passfire hole (it's filled by rammed BP so that it acts like time fuse) on top so that flames could be transfered to the charge...I haven't decided what to put on top yet.
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Looks nice to me! (God knows where this one is going to end up...)

Blaf

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Here is another look at almost finished device with container tube (shell) on top. There's no sharp point on this rocket...I've got suitable plastic tip, though. The top of tube is just folded and fixed with a hot-melt glue.
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Unfortunately, I had no chance to fire it yet!

Blaf

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Hi Blaf,
I want to try rockets soon, I might expect the holiday is an exelent oppertunaty to try to build some... So I have a couple of questions for you...
You made a rocket with :"plastic tube of some 7cm lenght, 10mm inner dia, bentonite end plug which later become a 3mm nozzle (drilling required)." Could I replace the plastic by a tube made from craft-paper or perhaps a tube wich is used for aluminium (don't know the word I'm afraid, very thin aluminium 'paper', maybe foil?)
Then another question, do I need to prime te stars or maybe put some BP between them so they can ignite all?
I'm afraid my English isn't that good but I hope you can understand my post :P

gr, Hellbound>LordOfDark

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Of course you can use a craft paper tube but it should be wound paralelly and glued with wood glue. Thickness should be (so they say...) at least 3mm...but if you make larger diameter tube the thickness should increase accordingly. To my knowledge, those cardboard tubes used for aluminium foil are convolutely (spirally) wound and have no strenght to withstand the pressure. If you look at the picture of big BP rocket I posted here last time...well, that one is made of sprally wound paper and when I fired it, it just pufffed and leaked the flame through nozzle and additional crack on tube body. Conclusion: rocket engines should always be made of paralelly wound paper.

Ignition of stars depends much of their composition. Charcoal fueled stars ignite quite easy while metal fueled stars ignite harder and need priming...some of them even several layers of prime. My Reeper Silver stars needed two layers to ignite. They could have ignited even with one layer but I implemented the second one just in case.

Hope this helps Lord of Dark.

Blaf

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Look at what is called "Mass Production"...

These rocket engines are made of plastic tubes remained from counter machines. So far they never failed... I placed my gas-torch beside for size comparison.
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Hope you all like it!

Blaf

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As an overture to NY mess I made a test of one of those small plastic engines I posted before. A live test in real time. Here I have to confes a little...as a payload I chosed commercial cracker, a big one which fits on top of the engine by its outher diameter. Well, a bit larger to be honest but it was not a problem, I wound a few additional layers of paper strip around engine and that sufficed. Crackers fuse (green Visco) was too long so I cut it to 1cm lenght and primed it with Meal+Dextrine slurry and dusted with meal right after for easier ignition. So, I mounted that big cracker on top with its primed fuse towards top of rocket engine. Of course, first I've put some granulated BP between those two and then wrapped a piece of craft paper around all. OK, stop with this tutorial crap....here comes the real thrill.
A day before I bought some tree lights, you know those small lights going off and on that you hang on your Christmas tree...well, those refused to work and I had to get them back to the shop. This was only an excuse, heh. I took my latest rocket with me, showed it under my jacket, tossed my lighter in my pocket and got out ready for action. On my way to that particular shop, I walked across an open space, future building site of some 100x100m...quite enough for test flight. Searching for suitable launch tube or something I spotted a large carboard box peeping out of metal container...just waiting to be of some use. And so, stabilizer stick was inserted into the corner of the box, slightly slanted....I lit the fuse and went away. The fuse was rather slow and I went 20m away and turned to see what's gonna happen. Right on time as the rocket started hissing furiously and took off leaving short sparkled trail behind. The height it reached must have been more than 35m when the burst charge went off separating the cracker from the rest. I could see its fuse glow spinning...and then....a nice bright flash coming from apogee followed by loud BANG hit my eyes and ears. Boy, it was scary. I pulled my cap deeper on my head and walked away like nothing happened. But inside, I was singing and dancing!
I made ten (10) more of those and if everything goes well I could set them off just before NY comes...

Blaf

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As I said, there are those bottle rockets I've told you about. You can see hot-melt glue holding sticks to plastic tubes.
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Something tells me that Duvel will like this...

Blaf

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At the same time, I made a few much bigger tubes from strips of craft paper some 12cm wide. Of course, I used wood glue for strenght. Sides are 3-4mm thick while inner dia is 20mm...hope these would withstand the pressure of burning fuel...
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And again, Duvel will slobber over it...no offence my friend!

Blaf

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I think you made some beautiful Bp rockets.....have you got any idea how much pressure (thrust) it dilivers?

I'm curious, what kind of a stuff you made for the big day.
(If you intent to post, please do so in this topic)

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They look really great, but aren't you afraid the stabilizer sticks fall off when the rocket engines get hot when you launch them?

The bigger tubes look very nice too, i think they shall be able to hold the pressure, wood glue gives pretty strong tubes.

You inspired me, i feel like making some rockets now too. :wink:

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As for the burning temperature issue and hot-melt glue, there's no real problem because BP fuel burns too fast to heat-up the plastic tube enough to loose holt-melt glue. Maybe, when whole thing descends and you get chance to hold it again, you would probably find the glue melting a bit. But the real problem, within those 2 to 3 seconds of thrust does not exist.
The question of Big Day is the right one...I have to admit, no special device is being made yet. Knowing me, I will probably go out and watch commercial firework display taking place every NY in my city port...and all of my devices will end up in my cousines sons hands. And I never ask for any copyrights!

I'm glad to be inspiring force of this forum and I would like very much to see your masterpieces guys. C'mon, do something!

Blaf

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Here comes the Great One!

Look at this beauty – its weight is hefty 75 grams! Feels great in hand, you've simply got that feeling of power. This box of matches is for comparison purpose only...the tube is more than twice as long as the match.
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If someone feels like seeing more, here is image of nozzle which is 5mm in diameter.
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And here, you can see the top end with passfire hole filled with rammed BP.
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Hope this nicely spices up the whole rush for New Year 2006.

Blaf

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Whaha.. ;)
Indeed, they're really nice.. Actually, I've never made BP- or other rockets.. I'm still making little fountains and starmines, I'll make a little mortar (2") in the future.. :P

Duvel

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And finally guys, if you would like to see something really nice, something of eternal beauty:

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I've never tried to launch device of such proportions...I just have to add a suitable stick, lite the fuse and hope to get away on time...

Blaf

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