OctoberSky0330 Posted March 13, 2012 Posted March 13, 2012 Hey guys I have been building Rcandy and BP rocket motors for awhile now. However, I am now looking for a stronger propellant that will produce more thrust. Can you guys please tell me how APCP works? I know it's a ratio with ammonium perchlorate acting as an oxidizer and fuel, and aluminum powder, with some kind of binder like epoxy resin. But exactly how does this reaction work? Also what kind of nozzle do you think can withstand the exhaust from APCP?Thanks guys
dagabu Posted March 13, 2012 Posted March 13, 2012 Hey guys I have been building Rcandy and BP rocket motors for awhile now. However, I am now looking for a stronger propellant that will produce more thrust. Can you guys please tell me how APCP works? I know it's a ratio with ammonium perchlorate acting as an oxidizer and fuel, and aluminum powder, with some kind of binder like epoxy resin. But exactly how does this reaction work? Also what kind of nozzle do you think can withstand the exhaust from APCP?Thanks guys It is unlikely that you will get a paper tube and clay nozzle to work with APCP, it just has too much power to be held by a pyrotechnical tube. -dag From Nichropulse: "APCP is the most common high performance solid rocket propellant used by experienced amateurs for high performance rocket motors. It is the same stuff that NASA uses in the space shuttle boosters. It consists of Ammonium Perchlorate, a binder, and usually aluminum powder, magnalium powder or magnesium powder for the fuel. The binder is usually HTPB or PBAN, however other binders such as silicone1 have been used. For high performance, a rough AP/HTPB/Al mass ratio is 70/15/15, and for low smoke compositions, the mix is closer to 80/18/21.2 Other fuels used with AP include rubber, polyurethane and nitropolymer.3 A small percentage iron(III) oxide (around 7%) is added as a catalyst in large high power motors like the Nasa shuttle boosters. Most APCP motors are designed as core-burners, especially when large in size. Common bore shapes include circular, C-slot, moon and finocyl. The geometry of the motor and core is called the propellant grain. Each type of bore shape will significantly affect the thrust curve of the motor. Nakka-rocketry has very nice page discussing different propellant grains. Particle size also has an affect on burn rate and the thrust curve. Generally, smaller particle size of the propellant constituents will yield a faster burn. Red iron oxide powder is often added as a catalyst to uniformly increase the burn rate. The ideal amount of added oxide usually lies within 0.5% to 3%4 depending on the binders and partical sizes. Many amateurs move to APCP propellant after experimenting with the black powder propellant because it is much more energy dense."
OctoberSky0330 Posted March 13, 2012 Author Posted March 13, 2012 1331605317[/url]' post='93408']It is unlikely that you will get a paper tube and clay nozzle to work with APCP, it just has too much power to be held by a pyrotechnical tube. -dag From Nichropulse: "APCP is the most common high performance solid rocket propellant used by experienced amateurs for high performance rocket motors. It is the same stuff that NASA uses in the space shuttle boosters. It consists of Ammonium Perchlorate, a binder, and usually aluminum powder, magnalium powder or magnesium powder for the fuel. The binder is usually HTPB or PBAN, however other binders such as silicone1 have been used. For high performance, a rough AP/HTPB/Al mass ratio is 70/15/15, and for low smoke compositions, the mix is closer to 80/18/21.2 Other fuels used with AP include rubber, polyurethane and nitropolymer.3 A small percentage iron(III) oxide (around 7%) is added as a catalyst in large high power motors like the Nasa shuttle boosters. Most APCP motors are designed as core-burners, especially when large in size. Common bore shapes include circular, C-slot, moon and finocyl. The geometry of the motor and core is called the propellant grain. Each type of bore shape will significantly affect the thrust curve of the motor. Nakka-rocketry has very nice page discussing different propellant grains. Particle size also has an affect on burn rate and the thrust curve. Generally, smaller particle size of the propellant constituents will yield a faster burn. Red iron oxide powder is often added as a catalyst to uniformly increase the burn rate. The ideal amount of added oxide usually lies within 0.5% to 3%4 depending on the binders and partical sizes. Many amateurs move to APCP propellant after experimenting with the black powder propellant because it is much more energy dense."
OctoberSky0330 Posted March 13, 2012 Author Posted March 13, 2012 Ok thanks, but do you know what kind of nozzle will hold? I think I will first try PVC for my casings and for the nozzel i was thinking durhams water putty...but I'm not sure. Any ideas?
emoskven Posted March 13, 2012 Posted March 13, 2012 i have built liquid engines and i found a bunch of different metal alloys will with stand high temperatures...i was using an alloy of titanium which held together nicely....try and find materials that have a high melting point...pvc would just melt under apcp...water putty might break apart..give it a try but i would recommend a metal alloy
dagabu Posted March 13, 2012 Posted March 13, 2012 Graphite rod cut to 1.5" lengths and turned on a lathe to approximate the De Lavale nozzle design would be the best bet. GRAPHITE ROD Schedule 80 PVC would not "melt" fast enough to fail using APCP but there is no way to bond it that would stand the pressures APCP creates. -dag
OctoberSky0330 Posted March 20, 2012 Author Posted March 20, 2012 hey guys please check out my first couple of rocket videos! please comment and tell me what i am doing wrong. Thanks! http://www.youtube.com/user/RocketMechanic1/videos
dagabu Posted March 20, 2012 Posted March 20, 2012 hey guys please check out my first couple of rocket videos! please comment and tell me what i am doing wrong. Thanks! http://www.youtube.c...echanic1/videos Sorry OS, you are doing it all wrong I am afraid. This forum is really about pyrotechnical rockets and not HP rocketry so our vision is all about the safe and eco friendly use of pyrotechnical items. The use of PVC is discouraged for various safety reasons as is copper pipe. Also, the use of a copper tube attached to a PVC pipe is just not going to work... ever. Hot glue melts below 200°F and is a poor adhesive in any case. I suggest that you look for a forum that is model rocket centric so that you can get the advice you seek without getting lambasted by the likes of me for using materials we just don't ever use in pyro. On last note, use e-matches, stop lighting a short visco fuse with your face 6" from the motor. You are just asking for an eye to be blown out. -dag
nater Posted March 20, 2012 Posted March 20, 2012 This forum is really about pyrotechnical rockets and not HP rocketry so our vision is all about the safe and eco friendly use of pyrotechnical items. The description of the forum on the list does say "discussion of low to high power rocketry". I've been around here long enough to know that just about everyone who posts here talks about pyrotechnics, but by the description of the forum alone, that may not be clear to new members. I lurk on a couple of the rocketry forums and they really frown on anyone making motors. TRF has a restricted forum that may be more open, but outside that forum, the rest of the TRF community says nothing positive about non-commercial motors. Some other forums also have experimental sections with some talk about rcandy, but not a lot of activity in general. I like all rockets. I would like to see any rocket discussion welcome. I would guess you would not find very many people in the dark side who didn't get their start with Estes models as a kid. It shouldn't matter if I tape my motor to a stick or shove it into the aft end of a rocket. Just have the expectation that the knowledge base leans towards pyrotechnics than sport rocketry.
dagabu Posted March 21, 2012 Posted March 21, 2012 The description of the forum on the list does say "discussion of low to high power rocketry". I've been around here long enough to know that just about everyone who posts here talks about pyrotechnics, but by the description of the forum alone, that may not be clear to new members. I lurk on a couple of the rocketry forums and they really frown on anyone making motors. TRF has a restricted forum that may be more open, but outside that forum, the rest of the TRF community says nothing positive about non-commercial motors. Some other forums also have experimental sections with some talk about rcandy, but not a lot of activity in general. I like all rockets. I would like to see any rocket discussion welcome. I would guess you would not find very many people in the dark side who didn't get their start with Estes models as a kid. It shouldn't matter if I tape my motor to a stick or shove it into the aft end of a rocket. Just have the expectation that the knowledge base leans towards pyrotechnics than sport rocketry. Well, slap me silly and call me Susan! I never did look at that. Never-mind then, carry on. -dag
oldguy Posted March 21, 2012 Posted March 21, 2012 (edited) hey guys please check out my first couple of rocket videos! please comment and tell me what i am doing wrong. Thanks! http://www.youtube.c...echanic1/videos Have a question for you.In your HUGE BLUE FLAME video.I know you called it APCP, but once well ignited, it appeared to burn off somewhat blue & near smokeless.Or possibly, any smoke was not in veiw of the camera lens?In any regard, what was the composition? EDIT TO ADD:Dag is giving you wise advice about using E-Matches from a distance. Edited March 21, 2012 by oldguy
OctoberSky0330 Posted March 23, 2012 Author Posted March 23, 2012 Yes, in my video you saw an APCP composition...I used aluminum powder and epoxy as the binder. The flame was blue because I added a very small amount of Copper Oxide (black) which serves as a catalyst to speed the reaction. This static test produced little to no smoke because the nozzle actually blew out immediately. I do not think this was because I used a weak nozzle (bentonite clay) but rather the material I used (PVC) melted so the nozzle blew out. I will be uploading another video to YouTube today with another static test of APCP. The nozzle of bentonite clay holds very well. I believe this to be the case because I used EMT tubing instead of PVC or copper. This material has a high melting point which serves as an excellent casing for my APCP motors. I did have one problem with the test however, if you watch the video later today you will see the motor choke, meaning there was not a constant stream of hot gas flowing out of the nozzle. I think this may be due to air bubbles in the propellant and I need to pack the APCP tighter but I am not sure. Please feel free to comment and give any suggestions. Thanks and I hope that answered your question!
oldguy Posted March 23, 2012 Posted March 23, 2012 If you recall?What was the percentage of AP, Al, copper oxide & what type or name brand epoxy did you use?
dagabu Posted March 23, 2012 Posted March 23, 2012 If you recall?What was the percentage of AP, Al, copper oxide & what type or name brand epoxy did you use? Psssst! OG, just go down to the local hardware store and grab a tube is GE Silicone ll, clear type. Make a "dry mix" and press it into a tube using regular tooling and see what you get. I would stand well away while testing since I have only used this material with re-loadable tubes and cannot vouch for the internal pressures of the motor. -dag
OctoberSky0330 Posted March 23, 2012 Author Posted March 23, 2012 For my composition I used 75% ammonium perchlorate, 7% Aluminum flake, and 18% epoxy. I believe the brand is locite, the epoxy I used sets in about 5 minutes, however, for optimum performance you should wait 24 hours for the epoxy to totally cure. When adding the copper oxide, make sure to put a tiny amount. When I say tiny I mean 1gram if you are making a 30gram batch.
Mumbles Posted March 23, 2012 Posted March 23, 2012 3% is still a pretty sizable catalyst loading. I don't know if I'd necessarily call that a "tiny" amount. We certainly allow discussion of pretty much anything related to rocketry here. I am completely fine with discussion of high powered rocketry as long as it's done in a safe and responsible manner. The general worry I get at times however is that we do not have the expertise available in our membership to properly give advice in some situations. I certainly do not want to see a major safety issue get overlooked. I know I only have a vague general understanding of the topic. There are much more experienced members in this area. What I don't think is a good idea is for people to start with experimental rocket motors and rockets. It'd do well to get a grounding in "traditional" high powered rocketry before advancing on to experimenting with their own propellants and designs. Octobersky0330, please make sure you have a good enough understanding to be doing this safely. Doing it right will be better in the long run as opposed to doing it right now. PVC and hot glue isn't going to cut it, it would seem.
OctoberSky0330 Posted March 23, 2012 Author Posted March 23, 2012 Ok thank you for the advice mumbles, will do.
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