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Blaf

BP Rocket

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I also made some rockets and they worked a little bit so here's the report.

Well with one thing I agree with the Americans and that is that "bigger is better".
No, I don't realy mean that but my craft tubbings where about 12 cm long and I didn't want to cut them in half so the rockets where quite big for a first time, but I had fun.
It is a long time since I ran that fast :lol:
So about the rockets they where about 12 cm long they had an ID of 11mm and a nozzle wich was 3.5mm.
When I lit the fuse of the first one and had retreated to a safe distance it went up for about 4 meters and exploded.
Well it did look nice :twisted: but I hadn't planed that would happen but nobody got hurt since we where at a safe distance my friend was even still runing when it happened so he didn't even see it.
Then I tried out the second one and that one flew for 20 meters or so and then suddenly turned sideways and flew for another 50 meters before it hit the ground and even then it still burned for a long time.
The third one had a small core I think so it didnt have enough thrust to get off the ground or my friend sticked it too deep in the ground but when I pulled it out it wasn't that stuck so I dont think that was the reason.
And finaly I lit the last one and this one had the same problem as the first one, it also flew for a couple of meters and then exploded.

I think that I know what the reason is for the cato-s.
Because the engines where so long and I rammed them pretty hard they bended a bit.
But the comp was realy hard (I noticed this during the drilling of the nozzles) so I think there was a crack in it and when the fire of the burning engine got to that crack it suddenly had a lot more comp wich caught fire and because the gasses couldn't escape fast enough it exploded.

And that's it for now more will folow soon!

Pirate

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Congratulations Pirate!

Welcome to the Club. CATO-s are unavoidable my friend so don't worry. Just keep fair distance from the launching site...and meanwhile, try to understand why things gone wrong.
Crack in the rammed fuel (as you said) could cause blow as well as loosely rammed fuel...but from your report I presume fuel was compact and well rammed. Inner dia of the tube compared to nozzle dia shows no irregularities too. Fuel lenght should be no problem either...12cm is way too long for 11mm inner dia, though...for that tube dia should be around 50mm or so. The only variable causing tube walls rupture that come to my mind is wall thickness - in this particular case it should have been at least 3mm. And yes, too long core could cause pressure buildup so I make almost non existent core to my motors...

Blaf

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Congratulations Pirate!


Thanks

The launching site I have used so far is good, it's mostly sand so there aint all to much risk of fire and it's big enough so you can run several 100s meters in all directions (except to the river but if you realy want you can swim) and there is a nice litle hill in the middle where you can launch the rockets.
And trying to understand why something went wrong is part of the fun then you can examine the remains and build some other test examples.

I made some new tubes yesterday so I can experiment some more this weekend.
But they are also about 12 cm long so I'll cut them in half this time to take a look what the difference is.

The wall thickness is around 3 mm I think but I'll have to measure it to be sure, but I will have to practice to roll good tubes because they still aren't that sturdy but they are getting better.

And about the core, my end plugs where somewhat on the large side about 1.5 cm so it was kind of difficult to tell how deep the core exactly was but I think they where about 1-2 cm.
But you say you make almost non-existent cores...don't you need them to get enough thrust to get off the ground and how deep do you make them ?

Pirate

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Well, my cores are at the most 10mm long and that's it. Usually I drill between 5mm to 10mm into the grain. This proved to work for me 100% with plastic counter-machine tubes that you can see in previous posts of mine. Of course, pressure would depend on burn rate of your meal too. I do granulate my meal before ramming...did you do it as well?

Blaf

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Ok, I'll test some rockets with a small core and take a look at wat the difference is.
But I'm planing to use only paper tubes, I don't want to work with anything plastic or metal since as you said there is always a risk for a cato.
My meal was not of a terribly good quality but hey it worked so it's good for starters but the first thing I need to improve is the quality of my charcoal.
And no, I didn't granulate my meal, I also don't know what it means :oops:
Somewhere on the net I did read an article of a guy who made pulverone with his meal and he said that it was better than standard meal.
He made his meal a little wet I think with water/alcohol and then pressed it trough a coarse screen and then he had a bunch of granules wich he set aside to dry and that was the pulverone.
Is that the same as your granulated meal or is it something else.

Pirate

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Yes, that's exactly the procedure I follow. My screen (kitchen sieve) is relatively fine with openings between 0,5 - 1mm, don't know for sure and granules coming out are very small. These are left to dry over night on a piece of news paper and later stored in plastic container. Granulation is done first because burn rate is more consistent and second, granules don't make powdery mess like meal does.


Blaf

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Ok, I tested some more rockets this weekend and they all worked nicely :D

They where the same in dimensions as the earlier rockets except I cut them in half this time so they where about 5-6 cm long and I also made the nozle 0.5mm smaller so it was 3 mm now.
I also made the cores smaller but with two rockets it was too small so they didn't ignite :cry:

Me and a friend made 9 rockets wich all flew this time (exept two) with no cato-s at all.
Three rockets had aluminium powder mixed with the meal powder so they left a nice trail of sparks in the sky when they flew. They only looked like they had a little less thrust than the regular meal rockets but they still got high enough.
I also made three rockets with a payload (one of them was one of the rockets wich didn't ignite) but because I still don't have suitable sticks my rockets where not as balanced as they should be.
So, the rockets with the payloads flew more to the side then upwards but since we were on our testing area it was not a problem.
The payloads consisted of legaly bought firecrackers (bermuda triangels). I know they aren't good for aerodynamics but they where good enough to experiment with.

Ok, that's it for now. My charcoal stash is gone so I'll first have to find/make some new but that won't take all too long and otherwise I can experiment with candy rockets.

I also recorded some rockets flying around so I'll try and post the vids this afternoon.

Pirate

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At the same time with latest fountain burn, I fired two small rockets...ehm, naked BP rocket engines made of those plastic tubes taken from calculator paper roles. Those wore newly rammed bentonite nozzles (see Tools, Nozzle forming tool) that are perfectly centered and smooth as a baby butt. Stabilizer sticks were made of two shorter wooden barbecue sticks taped together and worked OK. Both rockets flew straight up and ended somewhere in night sky. No payload was attached so I couldn't estimate their apogee but it's well over 50m. I couldn't get away from my cousines sons with just two small rockets fired....so I took out....well, check Roman candle topic.

Blaf

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Launch report

Look back to my post from April 27-th 2006. in Nozzle Forming Tool topic. You'll see a bigger rocket motor with nice smooth nozzle (thanks to my nozzle forming tool) waiting to be fired. In fact, I did it a week ago. I was camping with a few of my shooting buddies and basic plan was to sight in my big caliber rifle, nothing else. We took Jeep Grand Cherookie, loaded it with gear, drove two hours from our town and ended up on 1600 meters above the sea level, in beautiful deep valley, almost on top of the mountain. To open shooting festivities, I took my CD unit, 15 mts of wire, one bridgeless match, rocket motor....what, I forgot to take a stick! We looked at each other and went to search for anything that would stabilize the rocket. It was useless of course, what we could find was too twisted or short. Trees in the mountain do not produce much straight branches, you know, so I took what we had at hand. It was blasphemically bent, short piece of overdried tiny branch, not more than 60 cm in lenght. Too short for this size and weight of motor. But you see, my reputation was in question here....so launch was not to be cancelled. I connected everything, placed my rocket (bleah!) vertically between two large rocks, charged the CD unit and handed it over to my friend to fire it. We performed a countdown, just for fun, and he pressed the Button. My electric match worked as expected and the rocket went off, leaving brownish trail of smoke. Trajectory was slightly arched (due to branch-stabilizer) and at some 80-100 meters it started to rush downwards, while still burning. A small but thick forrest of beech-trees was some 250 mts from us....and my rocket was falling down right in the middle of it! Fortunately, burning ended much before.

Conclusion:
1. The burn time was too long. Remedy: Drill longer core next time.
2. Trajectory was disastrously arched. Remedy: Use straight stabilizer of suitable weight.

Blaf

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lol nice one blaf, positive that it went up, even with a bad stick. Were your friends impressed? Any payloads? :(

nice :wink:

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Of course they were...I could see respect deep in their eyes all day long. But no, there was no payload this time. It would have been waste of stars as we were there during daytime.
Thanks for positive feedback...

Blaf

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Three small skyrockets with payloads were fired a week ago to celebrate my aunts birthday. Look, to be honest, I don't need any special occasion to launch my rockets...this is just to make things more serious.
Two of them were straight rammed BP rockets while third one was half BP, half mixture of BP and Al-flitters (see Aluminium Flitters topic). Of course we waited until 21,00 to enjoy the effects thoroughly. First two were carrying a dozen small pumped stars each, first was filled with Gold & Silver Rain stars and second with Reeper Silver stars. They both worked superb, spread was good considering granulated BP burst charges I used. Of course, and again, burst went off at about 50 mts, too high for this size of rocket. The third one (50%BP-50%BP+Al flitters) was carrying a mixture of small firecrackers (you now those Chinese made tiny red crackers connected into belts of 100 pcs each?) and a dozen pumped gel-stars (see Stars topic). These were packed into simple tube made of craft paper which fitted nicely on top of rocket motor. This one was really nice to watch flying...it was leaving bright tail of shining Al pieces all the way up where it bursted spraying stars and producing a chorus of little cracks after they burned. It was really lovely...and kids were happy.

At least these worked nice which I can't say for my Toubillion...see appropriate topic, please.

Blaf

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That sounds great Blaf!
Looked like a 'Dragon Eggs' effect I suppose?

Hey, is there a chance that you can capture some of your devices on film?
So we can also see them! That would be very nice.

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Right, that final crackling sounded exactly like dragon eggs were on somewhere...but you couldn't see any flashes here.
As for video, unfortunately I haven't got a digital camera (for now), just simple Hi-8 VHS camcorder whos rechargeable battery almost died.

Blaf

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The last launch report:

Look back to Mk3 skyrocket image – that's the one fired two evenings ago. I sneaked out in rather warm night, no moonlight, with slight breeze from south. My pockets and hands were all occupied with Mk3 itself, torch gas lighter, pocket LED lamp, spare fuses if anything puffs blind, duct-tape, stick stabilizer of 80cm....ah yes, aluminium launch tube. I walked away about hundred meters from my house to abandoned piece of gravel beach with no light at all. That's why I needed my LED lamp...city lights were glimmering on my right and I was feeling like the last Man on Earth. Perfect – if you ask me. My hands were shaking a bit while assembly process but everything was set nicely, slightly bent to the seaside. I thought, if something gone wrong, everything should have ended up in sea water. I lit the fuse and retired a few meters....it took off in a furious hisss and reached some 50-70 meters but then started to descend, still burning. At some 30 meters the load thumped and spread weak fan of stars. Note that star shell wasn't spiked or reinforced in any way so I expected weak burst. Anyhow, the rocket did not (and I stress this again – did not!) explode...which should be considered to be a success. Moderate, of course, but still.

Any firings on your side guys?

Blaf

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Yes, i've fired a bp rocket a few weeks ago. Got a movie. :)

Rocket Movie

The take off wasn't very good, and the break also wasn't. (Just 4 Winokur #25 stars) But it looked nice.
And if you look well, you see that the break comes way too early. Have to improve that. The burst charge of the shell fired the rocket downwards. But it landed in the water.

gr,
Stijn

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Any firings on your side guys?


Actually, I fired one last weekend. It was on saturday evening, I was studying for an exam, but couldn't keep my toughts on it, as it was not the most exciting subject one could think of on a saturday evening :P So I allowed myself to take a little brake for a pyrotechnic quicky, and decided to produce a little rocket.

A week before I ground up some kitty litter. I used to make my rockets with fast setting cement, but ramming a plug is way more handy, faster and more fun. So I took a nice little 75mm long 12mm ID cardboard tube, a lovely fitting dowel, a big hammer, and started ramming the end plug. The result really surprised me, a fine smooth surface and rock hard. Also it amazed me that it's weight was far under that of a cement plug.

I continued ramming a few grams of standard BP mixed with a few % coarse aluminium, finishing with another nice plug. Then I drilled a 4mm diameter 40mm long core in one of the plugs, and put a 20cm viscofuse in it securing it with a piece of tissue. Althoug it was a quicky I decided that the rocket should carry a little payload so I drilled a 2 mm hole in the other plug and attached a small round shell, which was laying around :D Finally I attached a pretty straight bamboo-stick, and I was finished. Including the launch it took 20 minutes of my time, at most :)

The Launch itself was nice and surprisingly succesfull, as soon as the fuse was lit, I ran off, not being sure if it was gona work or just blow ... a loud woosh and a white tail of sparks disturbed the silent night. At, let's say, 30 meters the shell exploded, blowing out 10 streamers, giving a satisfying effect.

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Hello guys!

Just to give you a proof of life, I'm sharing these few images in praise of miniaturization trends. Make it small and beautiful...

This is a newly developed rocket engine but of modest size, 5cm in lenght, 8mm inner dia, 2mm wall thickness. Bentonite nozzle with 2mm exhaust hole...and that's it. Other items are there just for comparison purpose.


As you can see, nozzle looks like pro-work and performs excellent, of course.


Finished bottle rocket with flash charge. It's stabilizer stick is little more than 20cm long and I fired it off-hand with no problem with straight flight. They usually end up at little less than 50m height, no delay comp there so they go bang right after burn-out. I have to admit, I love these little things and my next move should be putting a small payload on top. We'll see...


That is it for now...

Blaf

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Hello guys

Here you can see the latest production of goodies. As you can see, the leading idea was that widely spread „small is beautiful“ one but if you carefully check the image, you should be able to spot two crackers of enormous size...well, I was carried away somehow. In fact, it was a specific order from my friends son, I had to keep to his specifications. Those small slim lined rockets are stuffed with small sip of flash powder and inevitably explode at apogee while those having green ball header are filled with BP chunks with crackle bits. Nothing spectacular but kids should love it. Unfortunately only one fountain was made due to lack of time...ehm, I know this is not an excuse but I had to say something in my weak defence. Here comes the image....

Blaf

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Hey Blaf,

Nice devices you've got there, thanks for taking the effort to post them in here!
Even though your post back in march remained un-replyed to.

May I ask you what kind of fuse you are using there? The kind your using for the rockets looks formiliar but the ones on the customized "1/4 sticks" you made appear exotic to me.

Best wishes in advance,

Amateur

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Hello Amateur

Nice Username, hope it doesn't imply your ignorance in the field, he, he. As for the fuse I'm using on rockets, it's my own make (you should check Visco Fuse Machine topic which I started almost 2 years ago) while the one seen on big crackers is commercial type – they call it Bickford type fuse. If I had used the thiner domestic type it wouldn't have looked nice on these big brutes! By the way, their dimensions are L=12cm, diameter is 3cm. Here comes the image...

Anyhow, thanks for your feedback...and if you have any questions, just go ahead!

Regards from Blaf

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