billofca Posted January 28, 2011 Posted January 28, 2011 In nozzled motors that is true, in nozzleless motors that is not true, in fact with the nozzleless motor, the larger spindle will have more off the line thrust. It is the choke or nozzle that creates the pressure, not the spindle. Yes indeed. My post was about BP rockets with nozzles. How ya doing Dag? Thanks for your great advice to point me in the right direction 2 months ago. I really appreciate that. Shoot any rockets lately? I shot off 4 one pounders today at the edge of the Hudson River where I knew I wouldn't have any complaints. All worked well. There was light snow falling and a light gray sky, so the video I took didn't turn out that great. My friend with me used a digital stopwatch to get the flight times. I was testing one type of delay pressed at different heights above the spindle. I tried two different fuels too. Fuel #1 - that I tried was 60-30-10 ball milled 3 hours (only air float C) and Fuel #2 - that I tried was 70-30-10 also ball milled 3 hours. With Fuel #2, 70-20-10 was ball milled with adding 10% more 80 mesh C after milling to give me 70 PN-20 C air float-10 Sulfur -10 C 80 mesh. My one pound tooling is the UH tool. Both fuels worked well, but fuel #2 flew the fastest and got the highest. altitude. Both had light weight flash report headers. The last two rockets, one was a flash header, and the 2nd was a 2" ball shell with red magnalium stars. Timing was all good. The rocket with the 2" ball shell was still traveling pretty fast when the shell broke, but at a good altitude. I now know about how much delay I should be using, and my next task is to make up different weight dummy headers filled with various weights of sand, and dial in the proper delay for 400 grams, 450 grams, and 500 grams of header weight. I will be making the motors without delays, just a clay bulkhead after 1 ID of fuel above the spindle. I want to time when the rockets start to arch over and find the peak altitude flight time for each of the heading weights. I will use 2 rockets for each weight and use only fuel #2. Since I last had a discussion with you, I have added an air operated oil pump to my hydraulic press. Wow, what a time and arm saver! Bill
dagabu Posted January 28, 2011 Posted January 28, 2011 Wlllydog, I have been stalking you on Passfire too Arent the Dans and Nski something? Once you get used to that air-over press, you are going to have to move on to a 12 volt powerpack model. I am still waiting till Dan T. pulls you into the 6# rockets and you get to launch your first 8" shell.
billofca Posted January 29, 2011 Posted January 29, 2011 (edited) Wlllydog, I have been stalking you on Passfire too Arent the Dans and Nski something? Once you get used to that air-over press, you are going to have to move on to a 12 volt powerpack model. I am still waiting till Dan T. pulls you into the 6# rockets and you get to launch your first 8" shell. Speaking of 12 volt power pack hydraulic pumps, I saw the Passfire project on building them, and saw many pictures of what different guys have built. They were very impressive and a rather very cool tool. About the only advantage they have is being portable as "power packs". I think it is a little out of my price range for a hydraulic operation. I spent $230 on my air operated pump where those guys probably have 10 times that much tied up in their builds. Plus, I have always believed that air is a bit safer around flammable stuff. You are quite right about the Dans and Nedski. Especially Ned, whom I have been having many PMs with. He told me my books got him into doing pyro, so I feel like a proud dad as his early mentor. He has gone way beyond what I could have taught him and he is at a master's level where I am now learning from him. I took a 15 year hiatus from pyro and am now getting back into it on the amateur level having now retired. Tom Rebenclau, the grand master and rocket king and I have been doing a lot of phone talking these past 2 months too. I have made plans to go visit him at his home in MA before winter is over. I have known Tom since the early 80s. He too paid me a nice compliment. He said to me that when he was first starting out in pyro, I was the only fireworks company owner who threw open my door to welcome him with open arms to come to my plant to work and learn. We had many conversations in those early years where he would come to the plant every couple of weeks and spend the weekend with me observing what was going on and getting lessons and ideas. He would come on displays and shoot some of his early shells, using my shows as his proving grounds. He is a great guy, and we hit it off as friends right from the start. Of course, he as with Ned has exceeded and gone very far with his knowledge, tools and techniques making superb fireworks and rockets. And like Ned, I am now his student, catching up on much needed knowledge from the inspiration his work gives me. I think I am about a year away from getting into 6 pound rockets. I might not even go there until I can get legal again. I might be able to talk my friend and former fireworks partner to give me some space at the plant where I did my commercial production with him so many years ago. I'll just have to wait and see how things go in the coming year. The problem with owning a commercial fireworks company is there is never time to experiment and work on fun stuff with all the pressure to produce and fulfill display contracts. The huge amount of materials and shells is so great (in the tons), there are way too many things to worry about that keep you busy managing. Now I have the time to work on one or two things at a time in the pursuit of perfection (like Ned and Tom). Hey Dag, when you are on Passfire, what handle are you using to ID your posts? Bill Edited January 29, 2011 by billofca
Guest no6 Posted January 29, 2011 Posted January 29, 2011 Thanks for your very interesting posts, Bill. There really is much more to this than I had originally thought! Tomorrow afternoon I'll video the rocket height and flight comparison for Juiceh. Will have to pound a screened mix rocket first thing in the morning. And we'll use the quick fuse at least one more time. Next I'll compare the two fusing methods side by side.
Guest no6 Posted January 29, 2011 Posted January 29, 2011 One more thing... I have a cheap plastic rifle case with egg crate foam from Cabela's. Is it OK to store and transport rockets in this? The motors are on the sticks and the nozzle is covered with painters tape, no fuse yet.
dagabu Posted January 29, 2011 Posted January 29, 2011 One more thing... I have a cheap plastic rifle case with egg crate foam from Cabela's. Is it OK to store and transport rockets in this? The motors are on the sticks and the nozzle is covered with painters tape, no fuse yet. no6, In transporting rockets, use a cardboard box and do like you said with covering the nozzle. The sticks should be attached on site and not transported with them attached though there may be others that dont agree,
dagabu Posted January 29, 2011 Posted January 29, 2011 Hey Dag, when you are on Passfire, what handle are you using to ID your posts?Bill Oh no, I cant make it that easy. Here is a hint, I have a picture of a hand built press in the hydraulic powerpack thread.
Guest no6 Posted January 30, 2011 Posted January 30, 2011 Well I fired three of the rockets today. #4 and #5 were the ball milled and no6 was the screened "green mix". The three were quick fused together and fired out of my mini mortar rack. We couldn't tell a dime's bit of difference between their performance. They took off at exactly the same time and reached pretty much the same height. Really bad video to follow. You'll have to give me a little time on this part.
billofca Posted January 31, 2011 Posted January 31, 2011 Well I fired three of the rockets today. #4 and #5 were the ball milled and no6 was the screened "green mix". The three were quick fused together and fired out of my mini mortar rack. We couldn't tell a dime's bit of difference between their performance. They took off at exactly the same time and reached pretty much the same height. Really bad video to follow. You'll have to give me a little time on this part. Congratulations, no6! It's all fine tuning from here on out. You have also inspired me to do more testing of my own rockets using non-ball milled fuel vs. milled fuel and timing them for altitude. Did your rockets all have a clay plug in the top? How far up beyond the nozzle did you insert your quick match fuse?
Guest no6 Posted January 31, 2011 Posted January 31, 2011 Thanks Bill. Yes, the bulkheads were all made with bentonite clay. However I must confess to putting some hot glue on top as an additional precaution. The next ones will not have the glue so we'll see how that goes. As for the fuse, "quick fuse" from cannonfuse.com was used. I cut a length of 7", taped it to a green visco leader, inserted the quick fuse all the way to the top of the spindle cavity and taped off the remainder to the stick to hold it in. It seems to work great. Will be trying Dag's inverted j-hook soon as well. My goal was to produce reliable motors for lifting shells and I think I'm comfortable moving forward with that now. Of course there will still be some tweaking of the formula as time goes on. And I hear one can make different color comps also. Hmmm.
Guest no6 Posted February 1, 2011 Posted February 1, 2011 One more thing... I have a cheap plastic rifle case with egg crate foam from Cabela's. Is it OK to store and transport rockets in this? The motors are on the sticks and the nozzle is covered with painters tape, no fuse yet. Does anyone else have an opinion on this? I'd love to hear your comments. Does the foam or plastic provide a potential spark problem? I'm worried about cracking my motors during transport. Just want to give them a safe soft ride to the shoot.
NightHawkInLight Posted February 1, 2011 Posted February 1, 2011 Does anyone else have an opinion on this? I'd love to hear your comments. Does the foam or plastic provide a potential spark problem? I'm worried about cracking my motors during transport. Just want to give them a safe soft ride to the shoot.It sounds like a fine idea to me. Where I would see a potential static problem is at the point when you open the case at the shoot and you touch the motors. Before that there is nothing for any static to discharge on. If you're really concerned you could lay a fine metal screen across one side of the foam and allow it to overhang the edges of the case. That should keep the electrical charge the same as its surroundings.
billofca Posted February 2, 2011 Posted February 2, 2011 Does anyone else have an opinion on this? I'd love to hear your comments. Does the foam or plastic provide a potential spark problem? I'm worried about cracking my motors during transport. Just want to give them a safe soft ride to the shoot. I don't think you have anything to worry about unless the foam is Styrofoam. If you are worried, simply wrap your motors in aluminum foil. It makes a great Faraday shield to protect the motors from ESD.
Guest no6 Posted February 14, 2011 Posted February 14, 2011 New question: I recently mixed a new 200 gram batch of rocket fuel. These rockets flew substantially higher than my previous green mixed ones. The formula was the same but this time the KN03 was run through a coffee grinder before screening. Could that have made the difference? They were a good 100 to 150' higher. Thanks, 6
Guest no6 Posted February 14, 2011 Posted February 14, 2011 Does ensuring a straight launch make for a straighter flight? Yes, it sounds like a dumb question as I type it but I'll take my chances.
Mumbles Posted February 14, 2011 Posted February 14, 2011 If your nitrate is somewhat granular to start with, then yes pre-grinding will make a difference. Much of the nitrate on the market is greenhouse grade, which as about the consistency of table salt, and generally designed for quick dissolving in hydroponic systems.
billofca Posted February 15, 2011 Posted February 15, 2011 Finely powdered chemicals work best for just about all fireworks projects. Grinding individual chemicals (never mixed) will give each particle in total a greater specific area and more intimacy when mixed with several passes through a 40 mesh screen. I uses a stack of different mesh sized sieves with a catch pan underneath for getting a homogeneous mix. Four to six passes through the screens seem to give the best results. All this effort results in faster burn reactions producing a hotter rocket fuel. You should always try to dial in to get a hot fuel until it CATOs the motor, than back off on the oxidizer or increase the charcoal to slow it a bit. Some of us use coffee grinders and others use ball mills for grinding just the oxidizer. Charcoal and sulfur are usually already finely powdered. Rockets seem to have a "mind" of their own at take off. Some will fly straight, while others may zig-zag until enough speed is reached where the wind drag against the stick fully develops stability. Some people add a second stick opposite the first to balance the drag forces on each side. The second stick can just be a short stick to catch the blow by wind drag. A longer launch tube up to the length of the stick also helps to stabilize vs. a short launch tube. Firing rockets on a windy day will also influence the path of a rocket. They tend to turn into the wind depending on wind velocity. - Bill
Guest no6 Posted February 15, 2011 Posted February 15, 2011 Thanks Mumbles and Bill. It is surprising to see how many variations there can be with such a simple mixture. Will definitely keep experimenting with small batches just for the fun of it. I made my launcher today to see if that helps with straighter flight. It's a 3/4" ID X 28" long steel pipe with threads on one end. It screws into a floor flange which in turn is screwed into a wood base. Should do just fine. Looking forward to using it this Sunday.
Guest no6 Posted February 15, 2011 Posted February 15, 2011 (edited) Finely powdered chemicals work best for just about all fireworks projects. Grinding individual chemicals (never mixed) will give each particle in total a greater specific area and more intimacy when mixed with several passes through a 40 mesh screen. I uses a stack of different mesh sized sieves with a catch pan underneath for getting a homogeneous mix. Four to six passes through the screens seem to give the best results. All this effort results in faster burn reactions producing a hotter rocket fuel. You should always try to dial in to get a hot fuel until it CATOs the motor, than back off on the oxidizer or increase the charcoal to slow it a bit. Some of us use coffee grinders and others use ball mills for grinding just the oxidizer. Charcoal and sulfur are usually already finely powdered. Rockets seem to have a "mind" of their own at take off. Some will fly straight, while others may zig-zag until enough speed is reached where the wind drag against the stick fully develops stability. Some people add a second stick opposite the first to balance the drag forces on each side. The second stick can just be a short stick to catch the blow by wind drag. A longer launch tube up to the length of the stick also helps to stabilize vs. a short launch tube. Firing rockets on a windy day will also influence the path of a rocket. They tend to turn into the wind depending on wind velocity. - Bill That seems counter-intuitive. It would seem they would be pushed by the wind. Is it that the lighter stick is pushed more so than the motor? EDIT: Meaning the top of the rocket is heavier and the bottom of the stick is lighter. Edited February 15, 2011 by no6
billofca Posted February 16, 2011 Posted February 16, 2011 [/b] That seems counter-intuitive. It would seem they would be pushed by the wind. Is it that the lighter stick is pushed more so than the motor? EDIT: Meaning the top of the rocket is heavier and the bottom of the stick is lighter. Think of the atmosphere as an "ocean of air". The current (wind direction) caries the whole rocket drifting with the wind, while at the same time the rocket has a center of gravity balance point somewhere along the stick near the motor. This is a pivot point to the rocket in flight. The stick being longer than the motor and having more specific area is also influenced by the wind. The stick will pivot on the CG by the wind acting on the trailing stick and arch toward the wind while the whole rocket is drifting along with the wind mass.
donperry Posted March 6, 2011 Posted March 6, 2011 I think I'll add vanes/fins instead of the stick. I'm scaling up to 1 inch ID rockets. I'll be using dry mixture with red iron oxide at first. Then r candy after. I just cannot make that much rcandy at once
Guest no6 Posted March 7, 2011 Posted March 7, 2011 How will you make your fins and nosecone? I'd love to hear it as I've thought about that, too. And I may get a free tiny altimeter in 2 months. Would really like to hear if anyone has measured the height these rockets reach.
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