douglas423 Posted October 14, 2015 Posted October 14, 2015 I pretty sure NASA uses carbon nozzles on their rockets, shouldn't we? Its a lightweight high-heat materiel. What are your thoughts on it? It can cost some and you would have to lathe it yourself. I'm thinking about making a few to test out and see if they work good!
MrB Posted October 14, 2015 Posted October 14, 2015 Hard to ram in to the rocket body, cost prohibitive, and, not really that much more effective then kitty litter...For ROCKETRY it's used quite a bit. But for our purposes? Not sure i see the point to be honest. The cost involved is such that you just add an increment or two of fuel, and get to the same / higher height, while still being cheaper.B! 1
pyrojig Posted October 14, 2015 Posted October 14, 2015 Why not use graphite ? lol you can lube your spindle then dip in graphite powder , it helps pull off the spindle easier while giving a carbon/graphite finish to the nozzles . Just my two cents . Mr.B does have a point , cost is a big factor in most makers eyes. Usually the cheaper option wins the race / ,
schroedinger Posted October 14, 2015 Posted October 14, 2015 There is an big difference in pyro rockets and high power rockets that use graphite nozzles. High power rockets use a casing made from metal that can hold such a nozzle. We use paper, nothing that can hold such a nozzle. Also in our core burnera we have thrust phases of not more them 1, 5 s and in end burners about max 10 s. A time where clay nozzles can still hold up. The high power rockets are using thrust phases of more then 2 minutes. A clay nozzle would been gone by now a graphite still works. Next thing pyro rockets are more like dispossable rockets, where high power rockets are retrieved and reused which makes us come ro costs. A 1 lb clay nozzle is depending out the nozzle mix maybe 3 cents, where a graphite nozzle is about 8 $ if you can make it yourself. Next thing time, a graphite nozzle takes at leat 10 min to lathe, a clay nozzle half a minute topress. And for a last qustion, no you cant just press a graphite nozzle, it chips when pressure is released, but you incorporate 10 % into your nozzle mix. 1
stix Posted October 14, 2015 Posted October 14, 2015 There is an big difference in pyro rockets and high power rockets that use graphite nozzles. High power rockets use a casing made from metal that can hold such a nozzle. We use paper, nothing that can hold such a nozzle. Also in our core burnera we have thrust phases of not more them 1, 5 s and in end burners about max 10 s. A time where clay nozzles can still hold up. The high power rockets are using thrust phases of more then 2 minutes. A clay nozzle would been gone by now a graphite still works. Next thing pyro rockets are more like dispossable rockets, where high power rockets are retrieved and reused which makes us come ro costs. A 1 lb clay nozzle is depending out the nozzle mix maybe 3 cents, where a graphite nozzle is about 8 $ if you can make it yourself. Next thing time, a graphite nozzle takes at leat 10 min to lathe, a clay nozzle half a minute topress. And for a last qustion, no you cant just press a graphite nozzle, it chips when pressure is released, but you incorporate 10 % into your nozzle mix. Yep, +1 to what shroed's said.
Arthur Posted October 14, 2015 Posted October 14, 2015 I've seen a view of an asbestos loaded phenol-formaldehyde resin jetstream liner with a graphite nozzle BUT that was for a large, high altitude rocket and would cost a fortune to make now. For DIY rocketry High performance rockets need good design and engineering, bottle rockets don't.
douglas423 Posted October 14, 2015 Author Posted October 14, 2015 Well Im not talking about using paper bodies. I'm also referring to high power rockets. You guys are right about it being pretty expensive but if you reuse it over and over it might be good. I'll try a pvc nozzle that i made sometime soon and maybe thats what ill use.
MrB Posted October 15, 2015 Posted October 15, 2015 Well Im not talking about using paper bodies. I'm also referring to high power rockets. You guys are right about it being pretty expensive but if you reuse it over and over it might be good. I'll try a pvc nozzle that i made sometime soon and maybe thats what ill use. This IS after all a pyro forum. If your going to talk about "rocketry" and not "Fireworks" type engines, there is a bit of knowledge around, but you might want to be clear, and explicitly state so in your posts.B!
stix Posted October 15, 2015 Posted October 15, 2015 Douglas, graphite to pvc is like one extreme to the other. PVC won't work well. What size, ie. diameter of the nozzles are you making?
dagabu Posted October 16, 2015 Posted October 16, 2015 The space shuttle SRB nozzles were (are) a cast product made from a *tape-wrapped carbon phenolic, and are nothing like what we would use in HPR or pyro. The centerline cutaway is shown below providing a glimpse into the engineering behind the nozzles used in the SRB. The HPM Nozzle is quite thin in reality, the throat is the thickest portion (of course) and erosion keeps them from being reused. *LMSC-HEC TR F225727 1
douglas423 Posted October 17, 2015 Author Posted October 17, 2015 Thanks for posting that dagabu! Thats really interesting.
dagabu Posted October 17, 2015 Posted October 17, 2015 Thanks Douglas. The point being that there is much we can take from military and NASA but like was already spoken above, for pyro, the nozzle must be cast/pressed in place and HPR normally use a nozzle once with a high value rocket stuck on top. There is just too much erosion in nozzles of any kind (occlusions and cracking as well) for any type to be used again.
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