THEONE Posted August 7, 2011 Posted August 7, 2011 (edited) Guys i am trying to make o PVC rocket put i have problem with the end cup... i loosing gases from it...I made with a coupler, 2 screws and cement ( because i can not find an end cup ) 1.avi Edited August 7, 2011 by THEONE
busspuppy Posted August 7, 2011 Posted August 7, 2011 (edited) Could you post some pictures please? I am having trouble understanding what you mean. Also I dont know if a pvc is a good idea. If it CATO's there will be a lot of shrapnel. Some other guys may have some insight on pvc rockets though. Please post pictures of the endcap so we can see what you are talking about. EditI think I may understand what you are talking about. I personally have never heard of that method being used. Have you tried making a plug from bentonite? Thats what is mainly used. You usually want the plug to be as thick as the thickness of the tubing (I believe) I would make it a little thicker to be safe. Also what kind of rocket is it? Is it bp based, cored, nozeless? Edited August 7, 2011 by busspuppy
THEONE Posted August 7, 2011 Author Posted August 7, 2011 (edited) OK here is how i make the end cap...The bentonite end plug surely will blow out because of the hight pressure... Also if CATO will occur.. nozzle or end cup will blow out, the pipe needs some thousands of PSI to burst333.bmp Edited August 7, 2011 by THEONE
busspuppy Posted August 7, 2011 Posted August 7, 2011 That has to be one of the strangest methods I have ever seen. I don't know how to help. What comp are you using and what size rocket? My suggestion is to try one rocket with the bottom have a plug of bentonite around the height of the ID or half of ID. If you are using a bp based comp ram or press it. Try adding extra bp to the top as a delay or use a bulkhead. I think the cement would be awful heavy and I dont see a point for it. Maybe some more expirenced rocket guys could help you. I am not sure if this is your first rocket or not but if it is I suggest you check out Nighthawkinlights tutorial for a bp based rocket. It is not advanced but it produces a nice result.http://www.youtube.c...nel_video_title It is not the best method but it works. Good luck and keep me updated. P.S. Do not ram anything but BP by hand.
THEONE Posted August 7, 2011 Author Posted August 7, 2011 (edited) I am trying to make a rocket with R-candy grains and cement-washer nozzle... http://www.youtube.c...h?v=wQqn_4YDqMo http://www.youtube.com/user/PyroTimo#p/u/11/cpxfIlOY0Bk Edited August 7, 2011 by THEONE
busspuppy Posted August 7, 2011 Posted August 7, 2011 That is very interesting Theone. Ok I am assuming the gas is leeking from the top is that correct? Somebody with more expirence with this type of rocket could help you more but I do have some ideas. How long are you letting the cement dry? I would let it set for about a week. It may not need that long but couldnt hurt, The thing that worrys me though is how the nozzel is connected. Make sure when you attach the coupler with the nozzel you securley fasten it so you dont loose gasses from the engine. I would probably mount the nozel straight to the rocket without the coupler. As i have not messed with these type of rockets I am not sure if you will be able to but I think you could. How the coupler mounts on looks like it could be prone to gas leaks. Again somebody else may be better able to help you but I hope this helps. I want to see this launch when you get it working. Just make sure your not under it when it comes down. It would hurt.
THEONE Posted August 7, 2011 Author Posted August 7, 2011 (edited) That is very interesting Theone. Ok I am assuming the gas is leeking from the top is that correct? Somebody with more expirence with this type of rocket could help you more but I do have some ideas. How long are you letting the cement dry? I would let it set for about a week. It may not need that long but couldnt hurt, The thing that worrys me though is how the nozzel is connected. Make sure when you attach the coupler with the nozzel you securley fasten it so you dont loose gasses from the engine. I would probably mount the nozel straight to the rocket without the coupler. As i have not messed with these type of rockets I am not sure if you will be able to but I think you could. How the coupler mounts on looks like it could be prone to gas leaks. Again somebody else may be better able to help you but I hope this helps. I want to see this launch when you get it working. Just make sure your not under it when it comes down. It would hurt. I am thinking to make the end plug directly without the coupler also let it dry more and add some fireproof silicone at the end to prevent the leakage... Look how it flies...http://www.youtube.com/watch?v=eMjurQHvLa8 Edited August 7, 2011 by THEONE
allrocketspsl Posted August 10, 2011 Posted August 10, 2011 (edited) OK here is how i make the end cap...The bentonite end plug surely will blow out because of the hight pressure... Also if CATO will occur.. nozzle or end cup will blow out, the pipe needs some thousands of PSI to burst when drilling holes in the tube or pvc or even steel you compromize what its intended to do.As soon as a hole is drill in anything you have completely changed it so the pressure its intended to take is only when its in the original condition.I made a aluminum rogallo hang glider in 1972,my brother and I, our father saw what we were doing and explained that drilling holes was crucial to get them in the correct spot or the tubing wont take the load it was intended to take.He designed steel for a living at US steel plant which in the 60's 70's was a big deal so we were careful the guy you need is Nakka,hes all knowing in this field trust me he knows his sugar Edited August 10, 2011 by allrocketspsl
r1dermon Posted August 10, 2011 Posted August 10, 2011 you need to use RTV (gasket sealer) on your forward closure to prevent blow-by. im surprised that you have a leak that didn't result in a CATO, most PVC motors i've built that were not well sealed have resulted in CATO's... http://www.nakka-rocketry.net/pvcmot7.html
THEONE Posted August 10, 2011 Author Posted August 10, 2011 (edited) Now i melt a little bit the coupler at the end and i turn it inside, after that i put cement without screws and it were worked wellThe mainly problem that i have is the PVC glue now, i live in Greece and here doesn't have any good pvc glue so i use superglue but it can not maintain so much pressure!!! Edited August 10, 2011 by THEONE
r1dermon Posted August 10, 2011 Posted August 10, 2011 you might try scuffing the end of the pipe and the inside of the coupler, and using a ketone solvent like acetone in order to "weld" the pieces together...this is hardly ideal, but may work better than CA glue. alternatively, you could try using RTV or silicone to bond the pieces, and use mechanical means such as screws in order to create a strong mechanical bond. if you try acetone, do it outside, as this solvent is quite volatile.
THEONE Posted August 11, 2011 Author Posted August 11, 2011 Have you ever try this, acetone melts the pvc ?
r1dermon Posted August 12, 2011 Posted August 12, 2011 acetone isn't the best solvent for PVC...but it's probably the best you can find off the shelf and for the money...you might try and chop some PVC into small bits, and dissolve it in acetone, then spread that on your pipe and fit the end-cap. unless you can find tetrahydrofuran, acetone is probably your best bet... (diethyl ether might work as well?) mostly sold as reagant solvents though, so they're not cheap when chemically pure. PVC sealer is a lot more cost effective. i can't believe you dont have access to any...?
Algenco Posted August 12, 2011 Posted August 12, 2011 if you have access to PVC then you also have access to PVC cleaner and cement
THEONE Posted August 13, 2011 Author Posted August 13, 2011 (edited) if you have access to PVC then you also have access to PVC cleaner and cement I have but the glue (PVC cement) is really useless !!!The glue we have here in Greece it can maintain only 16atm of pressure (235 psi)jamesyawn's motors are operated under 600-800 psi !!!..... Edited August 13, 2011 by THEONE
Mumbles Posted August 13, 2011 Posted August 13, 2011 I'm still not sure why you keep asking questions about rockets like these here. We have a relatively small population of people who build higher powered sugar rockets. You'd probably have much better luck on a forum or website that caters to such things. PVC is kind of a dirty word in pyrotechnics. I know there are safe ways to use it for higher powered stuff, but as much in the bottle rocket types of things we do.
r1dermon Posted August 14, 2011 Posted August 14, 2011 Id like to see some sugar motors used in convolute paper or FG tubes...could be a whole new dimension in fireworks.
allrocketspsl Posted August 19, 2011 Posted August 19, 2011 Id like to see some sugar motors used in convolute paper or FG tubes...could be a whole new dimension in fireworks. i used to use handrolled tubes for sugar rockets,went quite well with headers
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