Black Powder Rockets

[psymon]

Good news, I just launched a 3/4" rocket I made with my tools from pyrotooling.com and it worked fine. I did have to make the mixture a little weaker - something around 58\ 32\ 10. I worked out the problem its because the motors were not pressed hard enough.

One question I have for other users of these tools and rocket motors. How long does your burn last for? I would say from first ignition until the engine goes out it burns for about half a second. Just seems a bit too quick.

I have my own tools for making rockets and when I launch those I get a burn of around 2-3 seconds.

[moonshot]

Oops. Yeah Green Flame is right don't use dextrin for rocket propellent. I was getting it mixed up with lift BP. I grain 100 grams at a time using only about 2 tablespoons of water with a bit of alchohol to help wet it out. Then rub it through a small mesh sieve to grain it.

[moonshot]

Good news, I just launched a 3/4" rocket I made with my tools from pyrotooling.com and it worked fine. I did have to make the mixture a little weaker - something around 58\ 32\ 10. I worked out the problem its because the motors were not pressed hard enough.

One question I have for other users of these tools and rocket motors. How long does your burn last for? I would say from first ignition until the engine goes out it burns for about half a second. Just seems a bit too quick.

My 4" long 3/8 ID motors burn about 3-5 seconds which would be considered a pretty long burn time. It's because I ram about 1/2" of comp above the end of the spindle. The rockets take off fast then slow a bit before the break and have a good hang time. Try a bit longer tube and adding more comp above the spindle. If your putting a display header on your rocket you need some delay so the break doesn't go off too soon.

[cplmac]

I ram my BP rockets with no dextrin. My mix is 75/15/10 and I press it at about 10,000. Aside from the dust up everytime I slide in the ram it's not a problem. From what I understand most rocket motors burn in a second or so, everything after that is the delay comp pressed after the spindle+ comp wall diameter. The rest of the time they are basically coasting with a little thrust from the end burn of the delay comp.

[psymon]

So basically I should slow my powder down a little, make the nozzle a little longer or press more at the top as a delay. Ok sounds pretty straight forward. I guess the usual way everyone makes a passfire hole is with a small drill. Do you use some visco to get the fire to the effect shell or just dump some BP in there?

I am thinking of using some of my 35mm film cans as the star shell.

[cplmac]

I take a small drill bit and turn it through the clay plug by hand. You gotta try to go as little as possible past the clay because every mm to deep you go takes more time off your delay. I just fill it with flash throw an end disc on and strapping tape the end together. Making your delay longer is probably all you will need to do.

[moonshot]

So basically I should slow my powder down a little, make the nozzle a little longer or press more at the top as a delay. Ok sounds pretty straight forward. I guess the usual way everyone makes a passfire hole is with a small drill. Do you use some visco to get the fire to the effect shell or just dump some BP in there?

I am thinking of using some of my 35mm film cans as the star shell.

If your going to use a film can for your heading there are two ways you can go. You could cut a hole the same OD as your motor tube in the bottom of the can and glue the top of the motor into the hole. The pressure inside the motor will spit fire through the passfire hole directly into the header and set off the break. Or you can punch a 1/8" hole in the bottom of the can and use a small piece of visco inserted in the passfire hole in motor and threaded through the hole in the bottom of the can to deliver the flame to the header.

[psymon]

Just tested out a rocket with a film can salute header Fused with 2 cm of 1/8th visco. It went up great then after a second or so BANG! So the rockets are totally successful now. Thanks for the answers guys. At last I can launch decent rockets with headers now.Tonight I will launch one with glitter and 5 blue stars. I will go to a field to do it as the fallout can easily land on someone house and maybe damage something. From now on I expect to make several types of rockets, its nice to have varied display items.

 

Tonight also going to a display in Bedford, hopefully get some good ideas for future display items...

[saluterocket]

Sorry, allitle bit off topic, but here is my first rocket made with my homemade tooling. This test was to see if the rocket could take a festival ball sized payload up to a respectable height, it was a 4 oz rocket, and carried a 20 gram dummy(sand) allong with a 3 granite star payload, the stars are hard to make out, because it went soo high, here is the video

oh, and it was a core burner

 

http://www.youtube.com/watch?v=GKPzfEheKto

 

i am wondering if this flight is consistant with what a core burning 4 oz rocket should look like, it may be hard to tell from the video though.

[moonshot]

You must be doing something right because that looks like a good rocket. You could probably increase your header weight to 30 to 40 grams. Good launch, nice flight and I had to laugh when you came running out of the dark. It's always exciting when you light the fuse and the rocket takes off with a satisfying WHOOSH. Good work!

[saluterocket]

Thanks. Yea, those store bought four ounce rockets are crap, i was surprised how powerful these little guys are. tonight il try a 35 gram payload

[50caliber]

I finished making my rocket tooling for

2" Long, 1/4" Inside Diameter, 1/16" wall, 3/8" Outside Diameter tubes and I tryed out the 63 kno3, 27 sugar and 10 sulfur composition and they were perfect, very powerful. When I used black powder the rocket flew about 3 meters and then blew up, what do you think is the problem?

[saluterocket]

Dd you use a slow or "hot" mix of bp? Ifind that when using slow black powder, my rockets work fine, if fast meal powder is used catos occur, i also find like in your situation that the 2 / 1/4 / 1/6 casings to be very weak, try ramming the comp with less force, i found that even if the tube didn't show any signs of stress or fracture, it was still there, than when i lessend the force of raming i reduced my number of catos, hope that helped.

[50caliber]

oh ok thanks i might just mix some green mix and try that

[moonshot]

Yeah it sounds like your powders too hot. I'm using 71/ 24 /5 and it works good. I also roll my tubes a bit thicker than 1/16" and a little longer say 2 1/4" long so I can ram a bit more comp over the end of the spindle. This gives a longer burn time and some delay before the break. I like smaller rockets because they don't take so much comp and can be made quickly but are still fun to launch. Also once perfected you can scale your dimensions up to create larger rockets thet will perform well.

[Salute]

My first end burning rocket:

 

http://shrani.si/files/rockettool1097278.avi

 

I used none ball milled BP and used 1,5g flash powder for bang.

 

Photo:

http://shrani.si/thumbs/rockettool1097322.jpg

 

Btw my engine is made with home made tooling.

[Pretty green flame]

Question, how does silica sand mixed with bentonite work for nozzles. I've been having a lot of problems with my end burners and the main reason for them not flying i can come up with is the nozzle eroding and the rockets loosing thrust. So i want to fireproof my nozzles for better erosion resistance.

 

If it works, what particle size should i get

 

Kvarčna moka, fina, 7,5micron

Kvarčna moka, srednja, 44 micron

 

Kvarčna moka, groba, 100 micron

 

Kvarčni pesek 0.04 - 0.15 mm

 

Kvarčni pesek 0.10 - 0.25 mm

 

Kvarčni pesek 0.25 - 0.40 mm

 

Kvarčni pesek 0.40 - 0.50 mm

 

I can get these sizes, i was thinking along the lines of 0.25-0.40mm.

Note that i can not get GROG or fire clay, if i could i would get those two.

 

Thanks

[shadopyro]

Has anyone tried rammed dry plaster of paris for a nozzel?-maybe mixed with some bentonite?

I'll try it out as soon as my newer rocket tooling arrive.

[Salute]

Today I made static test of my rocket engine.

 

Total thrust: 6,2N

Time of burning: 0,8s

Total impulse: ~3,6Ns

 

Size:

Length: 65mm

Diameter: 16mm

Length of fuel: 40mm

Length of core: 30mm

Type of fuel: black powder standard formula(75:15:10), none ball milled .

Diameter of nozzle: 4mm

 

Video:

http://shrani.si/files/rockettool1110876.avi

 

Now I know that the engine could lift about 50g and reaches about 40-60m.

[Pretty green flame]

Guys i know i'm naggin a bit with my silica sand but since no one answered my question i guess i'm going to try it out, my silica sand arrived here today anyway.

 

I'd just like to know in what ration i should mix it with my bentonite.

 

Thanks

[shadopyro]

I've never tried it before, as the ground kitty litter that i use usually has some tiny pieces of granite mixed in.

I'm guessing that you want the sand to help hold the nozzel clump in the tube? so if i were to try it, i'd only use something like 5%- a small amount, as too much and it'll crumble easily.

 

You ordered silica sand? silica sand as in that fine white stuff? or just normal sand? (if it just normal sand you might've found a better bargain at the local garden centre -"sharp sand")

[Pretty green flame]

I ordered silica sand, the particle size is cca 315 micron so it's not exactly an extremely fine powder, cost me only 5$ for 5 pounds so it's not an al that bad a deal.

 

I'll try the 5% percent you reccomened, and see how it works.

 

Thanks.

[TheSidewinder]

Im not sure that Silica "sand" is going to work, especially if it's comprised of pieces that are round. For nozzles, you should use "Grog" (fractured, fired pottery shards) or other media that has flat, sharp edges, AND IS ABOUT 30 MESH. The sharp edges of the grog provide more "holding" power". Dave Sleeter's book has what I consider the best nozzle clay recipe. It's overkill, actually, but it works beautifully. Here's how to do it:

 

61% Bentonite clay

31% Grog

8% Paraffin Wax

 

Mix the clay and grog thoroughly, then heat it in a 300 F oven for a 1/2 hour. Melt the paraffin in a small pan, as hot as you can get it WITHOUT smoking or burning, then pour into the heated clay/grog mix. Stir it in briskly until no more lumps form. KEEP stirring unti it is completely cool.

 

Using paraffin lets it lubricate the mix, rammers, and tube as it is compressed. It gives you a denser nozzle by allowing the mix to compact more than if you use no wax. This is true whether you ram or press.

 

Hope that helped.

 

M

[shadopyro]

Thats why i recommended using sharp sand from garden centres.

PGF, tell us of how it works out, im thinking of doing the same for my stinger rockets.

 

Cheers

[Pretty green flame]

Thats why i recommended using sharp sand from garden centres.

PGF, tell us of how it works out, im thinking of doing the same for my stinger rockets.

 

Cheers

Will do, if all works out i'll do some test this weekend and report back here with my findings.

 

Just a note on the silica sand, the particles are not milled, and the sand IS NOT white but more of a dirty white colour, and upon closer inspection the particles are not round, more like needles. So i'm hoping for the best