hondo Posted December 6, 2007 Posted December 6, 2007 I purchased a 1 pound core burner rocket tooling and now I want to make girandolas which use end burning rockets for propulsion. its a two part question. first question, what is the thickness of the nozzel for rockets? I usually use about 10 grams of clay for the nozzel for core burners and it seems to work, fly high and no catos, now I made an end burner and drilled an 1/8 in hole for the nozzel, stuck it in the ground for a test burn and after the burn the nozzel hole was about 1/4 inch so I know the length of nozzel was not thick enough. so its obvious I need a thicker nozzel for the end burners. second question is the thickness of the nozzel of core burners and end burners the same? How much in grams do you use of clay for nozzels? I hope this make since
Gottagotomoz Posted December 6, 2007 Posted December 6, 2007 Ok, if I understand this correctly, you are asking how thick should a one pound end burner nozzle be. Now, I could be way off here so please correct me if am, but I have always aimed for a nozzle about as thick as the ID of the casing. I believe a one pound rocket is a 3/4" ID tube, so you would make the nozzle 3/4" thick. Like I said, I could be way off so don't take it from just me.
Mumbles Posted December 6, 2007 Posted December 6, 2007 Slight problem, you need end burners for girandolas. Anyway, the nozzle is generally 1 ID thick. I can't give this to you in grams, but IIRC it is around 1 tsp of clay, perhaps a little more. It will take a bit of tweaking.
Deceitful_Frank Posted December 6, 2007 Posted December 6, 2007 Yup, make your nozzle one ID thick or a little more. More cant really hurt although it does add weight to your rocket, nozzle erosion is reduced though which is a boon. Grind your clay as fine as your patience will allow and ram in at least three increments, preferably five. I use Al casings now as I found that cardboard can stretch in several days, loosening the nozzle. Aluminum seems to keep its spring indefinately. Finally, to take advantage of that pressure thrust remember to try to flare your nozzle with a knife. Having the exit area four times the nozzle throat area (twice the width) and a half divergence angle of 15 degrees works well. Happy and safe rocketry
lja Posted December 6, 2007 Posted December 6, 2007 Rather than make your nozzle thicker try a 50-50 mix of clay and kyanite. Even some grog tossed in with the clay will help with erosion a little. Kyanite is cheap, even skylighter sells it for for less than $3.00 a pound.
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