new2pyro Posted November 9, 2009 Share Posted November 9, 2009 here's a video of tonites rockets. mix seemed a little weak. the last rocket is a finned rolled rocket I made with a 10 gram 70/30 header. second video I will post later is 4 catos I had trying the hot bp on top of the spindle as suggested rocket_launch.wmv Link to comment Share on other sites More sharing options...
firetech Posted November 9, 2009 Share Posted November 9, 2009 Nice job. Gotta get those rockets up where they're supposed to be!! Link to comment Share on other sites More sharing options...
new2pyro Posted November 9, 2009 Author Share Posted November 9, 2009 Thanks I need to go hotter with my mix. It's 6/3/1 screened 3 times and hand mixed. Any suggestions? Also here's the 4 catos with the 75/15/10 on top of the spindle 4catos.wmv Link to comment Share on other sites More sharing options...
Pretty green flame Posted November 9, 2009 Share Posted November 9, 2009 Thanks I need to go hotter with my mix. It's 6/3/1 screened 3 times and hand mixed. Any suggestions? Also here's the 4 catos with the 75/15/10 on top of the spindle Try ball milling the stuff for 30-45minutes, and/or granulating it with some water and NO BINDER. Link to comment Share on other sites More sharing options...
Eric70 Posted November 9, 2009 Share Posted November 9, 2009 new2pyro, The fuel on top of the spindle is the delay mix and should be the same fuel as the rest of the rocket. That seems to be a rule of thumb from what I have read the past 6 years and I believe it. Using a hotter mix above the spindle is the cause of your catos or greatly contributing to it. I experienced it firsthand last year, I ran out of one batch of BP at the top of the spindle or barely past it. I had some hotter mix so thought what the heck use it for the delay. The rocket blew up right after it left the launcher. I think the reason for the catos would be that the hotter delay mix ignites, burns faster and therefore cause the rest of the engine to burn quicker than it should. I have made over 100 1lb BP cored rockets the past 3 years as of October (2009). They are dialed-in and if you or anyone wants to start a thread to exchange information and specs on making these, I would be game for it. Everybody has a different way of going about it, I'm sure. Thanks I need to go hotter with my mix. It's 6/3/1 screened 3 times and hand mixed. Any suggestions? Also here's the 4 catos with the 75/15/10 on top of the spindle Link to comment Share on other sites More sharing options...
Mumbles Posted November 9, 2009 Share Posted November 9, 2009 Another member here, Dapaki, was discussing this a few days ago. He said he needed the hotter mix above the spindle to prevent the rockets from returning to the ground. It can be done, but like many other things it probably has to be dialed in. Link to comment Share on other sites More sharing options...
Eric70 Posted November 9, 2009 Share Posted November 9, 2009 I think for somebody new to making rockets, the homogenous fuel rule is the best way to go - same mix top to bottom. After a person has established a successful pattern they should attempt to work on variations. I have stuck with using the same mix top to bottom except this year I started adding a pinch of spherical Ti to the upper half of the delay mix for sparkly effects. The next thing I would like to try is adding colored comps for a delay. I don't know about Dapaki's hotter mix above the spindle. I am not saying he is wrong, I don't have much background on it. Like I said everybody has different way of going about it. I am not a rocket scientist (literally) but with the BP core-burners the thrust generated to shoot the rocket up occurs the first 1 or 2 seconds. The delay mix is just that - a delay mix to buy time before the header is ignited. The cored part of the rocket is where the thrust generation occurs, upon ignition the space left by the cored tooling allows a combustion occur that rapidly builds up thrust the first 1 or 2 seconds. This is why fuel for coreburners can be handmixed and of lower quality. Another member here, Dapaki, was discussing this a few days ago. He said he needed the hotter mix above the spindle to prevent the rockets from returning to the ground. It can be done, but like many other things it probably has to be dialed in. Link to comment Share on other sites More sharing options...
psyco_1322 Posted November 9, 2009 Share Posted November 9, 2009 new2pyro,Are those motor pressed or are they pounded?-If they are rammed, I would suggest a bigger hammer. You'd be surprised what a bigger hammer can do for your rockets. It could be the charcoal you use that's affecting the performance of your fuel too. I would try some hand mixed 75:15:10 with a moderate charcoal. Something like pine. I would also suggest that you wax your fuel, kinda like Vaseline or mineral oil in whistle. Melt some wax down (3%), crash in some lacquer thinner, and then dump into your fuel, mix around, and granulate or just dry it. That will give you a fuel that consolidates very well. If that fuel is still too hot, you can add a few more percent of wax or switch to a different charcoal. You should be able to pick up a big bag of nice, shitty, Royal Oak charcoal from walmart for under $10. Its good for things like rocket fuel, or places where the charcoal is really just an auxiliary fuel. It's no way suitable for hot bp or lift. Link to comment Share on other sites More sharing options...
Richtee Posted November 9, 2009 Share Posted November 9, 2009 here's a video of tonites rockets. mix seemed a little weak. the last rocket is a finned rolled rocket I made with a 10 gram 70/30 header. second video I will post later is 4 catos I had trying the hot bp on top of the spindle as suggested Damn I thought he said "lunch" Rocketry is something I missed, as I had to bow out of the hobby prematurely. It IS an art unto itself. Not a bad start tho! Carry on, and folks here will help. Link to comment Share on other sites More sharing options...
fireworks Posted December 3, 2009 Share Posted December 3, 2009 (edited) Nice timing with the salute on the last one, that extra bit of delay adds a lot. Edited December 3, 2009 by fireworks Link to comment Share on other sites More sharing options...
dagabu Posted December 3, 2009 Share Posted December 3, 2009 I don't know about Dapaki's hotter mix above the spindle. I am not saying he is wrong, I don't have much background on it. Like I said everybody has different way of going about it. A homogeneous mixture all they way through is fine just like almost everyone agrees but that was not the question, it was about getting the rocket to continue to climb and carry a payload using the fuel above the spindle to provide the necessary thrust. If you use a short spindle like a stinger or a whistle spindle, the fuel on top of the spindle will essentially be pushing an end burner and the fuel needs to be pretty hot to do that. Think of it this way, a core burner spindle allows for a large surface to burn at once allowing for immediate thrust needed to get the rocket off the ground, only the end of the grain is burning on an and burner and does not allow the thrust to form for propulsion. What I think happened to the rockets (static testing will show) is that the fuel is burning through the casing wall and causing the CATO. End burners demand a thick case wall due to the longer fire time, core burners are gone in 1-1.5 seconds, end burners can go 5 or more seconds and eat casings for lunch. Finally, this is where convergence and divergence is so important. The burning fuel must be funneled to the nozzle and away from the sides of the motor casing or else it will burn through where it is forced to the wall. Convergence is important too, after all have you ever seen a military or civilian rocket without a bell? I haven't. Tests show conclusively that you will get straighter flights, more usable thrust, better venturi allowing for hotter fuels (the venturi allows for the outgoing gasses to pull the gasses out of the casing faster). Skeptics: Use your hot fuel to make two motors, make one with no convergence or divergence and one with. IF you don't CATO, notice which flys higher, you will be amazed. D Link to comment Share on other sites More sharing options...
Eric70 Posted December 3, 2009 Share Posted December 3, 2009 (edited) Think of it this way, a core burner spindle allows for a large surface to burn at once allowing for immediate thrust needed to get the rocket off the ground, only the end of the grain is burning on an and burner and does not allow the thrust to form for propulsion. What I think happened to the rockets (static testing will show) is that the fuel is burning through the casing wall and causing the CATO. End burners demand a thick case wall due to the longer fire time, core burners are gone in 1-1.5 seconds, end burners can go 5 or more seconds and eat casings for lunch. D Dave, This has been a good read. I don't think any point was missed in this thread. Your name came up in the process. It just sometimes seems in this forum that when a newcomer to rockets starts asking questions there is, in my opinion, a fair share of good, well-intended but unpractical suggestions that would be best left for advanced pyros such as yourself. Is it a big deal? Hell no. Don't be offended, your input is appreciated. Keep it coming. My ramblings in the paragraphs of this post are not directed solely at you or certain pyros like you. Just don't be surprised if I sometimes chime in and say something. I have some experience but I am not an expert and I don't want anybody to think I am. I could care less. If someone new ends up subscribing to my keep-it-simple mentality, great. They will be less likely to give up in frustration and in a few years be going towards more advanced work. Yes, there certainly is a difference between cored burners and the end burners. You are working with end burners, now that I know that, I now understand what you are saying. The question pertained to why new2pyro was experiencing weak performance and catos, he asked for suggestions. The subsequent dialogue brought up your name and steered the thread towards further investigating the possibility of using a hotter delay mix to keep the rocket going. For coreburners I have never read anything about that. Endburners, that seems to be a different story but something I have not read until now. Again, I am not saying you are wrong and you graciously made it clearer in your latest post. Guess I will have to dig out David Sleeter's book and see if there is anything in there about the hotness of delay mixes. new2pyro indicates he launched cored 1 lb BP rockets and that is a type of rocket I have experience with. I have no experience with making end burners. I think one of the first routes for a newcomer would be to slow down the burn rate of the fuel. If your coreburner catos, seems like everybody and their brother will suggest that more charcoal needs to be added or less KNO3 in the next batch. The other things to check for is how well one is consolidating the fuel, i.e. too big of increments or too much force that would cause cracks in the grain. To paraphrase old text readings, If the BP rocket is too slow, add more saltpeter, if it explodes, add more charcoal to slow down the burn rate. Simple. Edited December 3, 2009 by Eric70 Link to comment Share on other sites More sharing options...
Ericz Posted December 3, 2009 Share Posted December 3, 2009 If you use kno3 some sugar and fe203 you can lift those small payloads easy. Its dumb but i dont have a mill so i hand mill it for like 30 minutes ( 50 gram ) And i make 3 rockets out of that i can lift 30 gram salutes with it. 22 mm tough. Saver mix and maybe not so many cato's i did cores all the way trough and i did without core. Very small holes also maybe 1/4 or 1/5 of my ID.Never had 1 cato. Greetz, the mix compo i use is 65:35:1 kno3,Sugar,fe203. If you do some Ti or Fe trough it like 2-5 % it makes a nice little tail. Or stay with the green powder what u want Link to comment Share on other sites More sharing options...
dagabu Posted December 5, 2009 Share Posted December 5, 2009 Dave, This has been a good read. I don't think any point was missed in this thread. Your name came up in the process. It just sometimes seems in this forum that when a newcomer to rockets starts asking questions there is, in my opinion, a fair share of good, well-intended but unpractical suggestions that would be best left for advanced pyros such as yourself. Is it a big deal? Hell no. Don't be offended, your input is appreciated. Keep it coming. My ramblings in the paragraphs of this post are not directed solely at you or certain pyros like you. Just don't be surprised if I sometimes chime in and say something. I have some experience but I am not an expert and I don't want anybody to think I am. I could care less. If someone new ends up subscribing to my keep-it-simple mentality, great. They will be less likely to give up in frustration and in a few years be going towards more advanced work. Yes, there certainly is a difference between cored burners and the end burners. You are working with end burners, now that I know that, I now understand what you are saying. The question pertained to why new2pyro was experiencing weak performance and catos, he asked for suggestions. The subsequent dialogue brought up your name and steered the thread towards further investigating the possibility of using a hotter delay mix to keep the rocket going. For coreburners I have never read anything about that. Endburners, that seems to be a different story but something I have not read until now. Again, I am not saying you are wrong and you graciously made it clearer in your latest post. Guess I will have to dig out David Sleeter's book and see if there is anything in there about the hotness of delay mixes. new2pyro indicates he launched cored 1 lb BP rockets and that is a type of rocket I have experience with. I have no experience with making end burners. I think one of the first routes for a newcomer would be to slow down the burn rate of the fuel. If your coreburner catos, seems like everybody and their brother will suggest that more charcoal needs to be added or less KNO3 in the next batch. The other things to check for is how well one is consolidating the fuel, i.e. too big of increments or too much force that would cause cracks in the grain. To paraphrase old text readings, If the BP rocket is too slow, add more saltpeter, if it explodes, add more charcoal to slow down the burn rate. Simple. Eric, As a fellow Minnesotan, I expect to see you this spring at the Spring NLP shoot, I'm gonna hunt you down if you don't! That was just about the most courteous and well thout ought way of saying, "Oh screw you!" I have ever read and I stand corrected and apologize for over stepping. On to the subject at hand. Core burners should never be made longer than one increment past the spindle tip until the fuel is known to be stable. That is a law of rockets and anyone that flirts with that law is going to experience a lot of needless growing pains. Oh screw it, you know what? I blew up a full dozen new rockets this last fall at a shoot and loved each and every one because I learned a lot about my fuel, my casings, the ball shells I was lofting. Ask Sidewinder, I'm sure he got a kick out of the "ground flowers" too. In fact, my favorite part of this years PGI was watching the rockets blow up! We all shouted "AGAIN!" every time the 6" ball shells blew up in the rack! I may come off poorly but I, above all have made every mistake that can be made in pyro and just want you all to benefit from my failings. That being said: Eric, Share, interject, be bossy but most of all, post your videos of those 100 plus rockets because the rule is: If it aint on video it dodn't happen! D Link to comment Share on other sites More sharing options...
Eric70 Posted December 5, 2009 Share Posted December 5, 2009 Hopefully new2pyro found this thread helpful and I apologize for going off on a sidestreet here. It's still in the neighborhood... ---------------------------------------------------------------------------------------------------- Dave, As a fellow Minnesotan, I expect to see you this spring at the Spring NLP shoot, I'm gonna hunt you down if you don't! I would like to show up, we'll see what happens. You guys will probably lynch me That was just about the most courteous and well thout ought way of saying, "Oh screw you!" I have ever read and I stand corrected and apologize for over stepping. Courteous, I try to be. "Screw you" wasn't the intent. I wasn't trying to bash you, just attempting to get things into focus. Oh screw it, you know what? I blew up a full dozen new rockets this last fall at a shoot and loved each and every one because I learned a lot about my fuel, my casings, the ball shells I was lofting. Ask Sidewinder, I'm sure he got a kick out of the "ground flowers" too. In fact, my favorite part of this years PGI was watching the rockets blow up! We all shouted "AGAIN!" every time the 6" ball shells blew up in the rack! I think my buddies get even more amusement from my catos. I had several 3 lb rockets and one 6 lb rocket blow to hell on the launch pipe, those watching thought it was really cool. Yeah, I admit it was fun but part of me was disappointed by the loss of materials. Three years ago my first few 1lb ones started out in the opposite direction (weak lift). The bigger ones I had to slow down the mix. The 3 lb ones are dialed-in as of October - made 20 of them in the past 1 1/2 years to get there and they may be slightly weak now. Still working on the 6 lb formula. Share, interject, be bossy but most of all, post your videos of those 100 plus rockets because the rule is: If it aint on video it dodn't happen! The stuff I say here is small potatoes and light years behind stuff discussed in Passfire. I am just trying to help others who are starting out like I was a few years ago. I learned from mistakes, too, and want to share information that will minimize a newcomer's frustration. As for videos, I am overdue and dumber than a box of rocks when it comes to the subject. Not sure if a digital camera will get the job done. I think there is a thread in here about doing videos or I will start one. We can take that topic up there. I'll get some recorded this winter if I can do it without freezing my sack. I just ordered some willow charcoal, I can't wait until next spring to see how the 4 oz and 1 lb rockets perform. I might just have to start making my own charcoal. Eric Link to comment Share on other sites More sharing options...
TheSidewinder Posted December 5, 2009 Share Posted December 5, 2009 Hey, those ground breaks were one of the highlights of the meet! That, and: 1) Eric Hunkins' spectacular double beraq. 2) The excellent food 3) The camaraderie. Looking forward to visiting again. And Eric70, I expect to see you there too. M Link to comment Share on other sites More sharing options...
WonderBoy Posted December 8, 2009 Share Posted December 8, 2009 (edited) Eric, That willow can really make a difference. I replaced just half of the airfloat lump charcoal in my 1lb'ers with airfloat willow and went from pretty good performance to cato's every time. Jeff Edited December 8, 2009 by WonderBoy Link to comment Share on other sites More sharing options...
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