TYRONEEZEKIEL Posted August 16, 2009 Posted August 16, 2009 Tonight I built a 3/4" ID by 6" pvc motor. pipe weighs 50g and I put about 20g of stars in it. my total motor weight is 125g the nozzle is 3/4" thick and my mandrel is 15/64" and will be and endburner as of now. I have a 4' section of 5/16" dowel that Im using for stability. and exceeds the 42" needed to be 7x the motor length. The balance point is about 2" under the nozzle, so Ive got my center of gravity right. my header is simply a clay bulkhead with a passfire hole through it. I left an inch of tube for stars, and extended the tube by using masking tape to hold a bit more stars. I then spiral taped the stick all the say up the motor. first with 1/2" tape, then 1.5" tape. It feels very solid, but I may add more for piece of mind. Any way, does anyone see anything wrong with my rocket? This will be my biggest one to date, and I'd rather get good counsel before I flew it rather than guess and checking. Thanks
TheEskimo Posted August 16, 2009 Posted August 16, 2009 I would just be a little leery of lighting 1 pound endburner made out of PVC for 2 reasons:1. Obviously, if something goes wrong, shrapnel,and 2. If the neighbors find a hunk of PVC with a dowel attached to it in their yard the next morning.Why not just go with a paper tube?
Eric70 Posted August 16, 2009 Posted August 16, 2009 Good luck with it! You should test it in a desolate area, out in the country somewhere. I agree with TheEskimo on the safety issues. PVC might be easier to obtain than ordering paper tubes or rolling your own but you should switch over to paper. I would also wonder how well a clay nozzle will grip to PVC - that I don't know. Richard Naaka's rockets utilize cement and metal washers but that is for rocketry, not pyrotechnic rockets. As for center of gravity, I dial it in *above* the end of the engine (on the tube) at least a finger's width. I used to dial it in 1-inch below the engine and it flew alright but having the center of gravity above the end of the engine gives me straight predictable flights. There seems to be a split camp on the center of gravity for pyro rockets.
TYRONEEZEKIEL Posted August 16, 2009 Author Posted August 16, 2009 I definitely am NOT going to launch this in any where near a neighborhood. I am thinking over a lake or some dirt field. This way, no fire, and we will have a extra long fuse to light. Also, what should I launch it from?? I pvc pipe buried in ground?
Seymour Posted August 16, 2009 Posted August 16, 2009 That sounds right. Just any tube that the stick can freely slide out of.
PyroMan16 Posted August 16, 2009 Posted August 16, 2009 What type of fuel are you using?Big PVC motor are tricky, especially with sugar propellent! Even the smallest crack or problem and the whole thing will blow.
TYRONEEZEKIEL Posted August 16, 2009 Author Posted August 16, 2009 haha.. sorry. It is a BP rocket. Ive used this fuel zillions of times before, so i know it is reliable.
dagabu Posted August 16, 2009 Posted August 16, 2009 (edited) "the nozzle is 3/4" thick and my mandrel is 15/64" and will be and endburner as of now" HUH? Nozzle and endburner? Can you post a pic? Here is a post of my two stage rockets that I flew at PGI last week. They are 1" core burners with a 75 gram header. I am concerned if your rockets are packed in PVC, VERY dangerous! And that they are end burners. I suggest that you remove the heading and static fire it inside a cinder block then go and get some paper casings. I can help with the casings, please don't shoot that aerial pipe bomb, Police really don't like them! Edited August 17, 2009 by dagabu
TYRONEEZEKIEL Posted August 19, 2009 Author Posted August 19, 2009 I think I may actually scratch it all out, and start over with a paper casing. it would be lighter and it would be less danger. what I mean by endburner is that there is no core in the fuel. the nozzle is as deep as it gets, as opposed to a cored rocket which will have greater thrust due to greater surface area, but also greater pressure and not so good for pvc or weak paper.
PyroMan16 Posted August 20, 2009 Posted August 20, 2009 You could still use the PVC pipe. Or at least try (wouldn't wanna waste). If your nozzel is 3/4¨ thou just hand drill another 1/4¨ or so. This will increase the speed to make up for the extra weight of the PVC. Works for me.
Ventsi Posted August 20, 2009 Posted August 20, 2009 PVC Rcandy motors tend to be quite common. However the most care needs to be taken when choosing the type of PVC and asembling the cast grain motor. Mr. Yawn does it and the guy has some expirience. I absolutely wouldnt use it as a normal firework type rocket. The model/ameteur motors have steel washers , reusable casing , bates grains and wouldnt really be "reusable" after a 3" shell just burst next to it. Just stick to cardboard, buy some if you're into rockets, or just roll your tubes if you're testing the waters.
TYRONEEZEKIEL Posted August 20, 2009 Author Posted August 20, 2009 I am big time! into amateur rocketry. I mix my own APCP all the time, so Ammonium perchlorate is never in shortage And I would never think of using my AMW casings for fireworks rockets. EPIC waste.
TYRONEEZEKIEL Posted August 22, 2009 Author Posted August 22, 2009 Well.. I took it out to a lake and flew the rocket last night. It worked like a charm. Lift off was incredibly slow. it was really neat, like a girandola... but it may have been a bit on the unsafe side. More nozzle pressure is what I needed, so next time I will switch to paper, and use better nozzle geometry. Maybe use a better BP formula isntead of plain ole meal.
PyroMan16 Posted August 23, 2009 Posted August 23, 2009 You could try making a core burner. It should lift off faster by using paper tubing too. Good job thou!
TYRONEEZEKIEL Posted August 24, 2009 Author Posted August 24, 2009 No problem, What are some good rocket BP variants. I looked on pyroguide, but they just add 325 spherical aluminum and granulate??.. Im not so sure about that. Plus I dont have a press, so I will be ramming. Thanks
PyroMan16 Posted August 26, 2009 Posted August 26, 2009 Never tried it but I bet it works, just as long as you know the ratios. Just ram it with a wooden ram and a dead blow mallet and it should be fine.
dagabu Posted August 28, 2009 Posted August 28, 2009 No problem, What are some good rocket BP variants. I looked on pyroguide, but they just add 325 spherical aluminum and granulate??.. Im not so sure about that. Plus I dont have a press, so I will be ramming. Thanks There was an horrible accident just lately involving a BP rocket and metal composition. I wont pound anything bigger then a spolette sized bottle rocket and I wont ever pound any metal composition... period. I think you may want to buy some heavy leather gloves for the holding hand, get a dead blow hammer (3#) and a pounding post (8x8"). Stay with BP, make it hotter or cooler by ballmilling or adding charcoal. PM me for particulars. Dave
Mumbles Posted August 28, 2009 Posted August 28, 2009 If you're talking about the individual at the WPAG, I don't think that comp contained any metal. That was the second individual I know personally that had a rocket blow up while pounding a rocket. Even ramming straight BP makes me uneasy.
dagabu Posted August 28, 2009 Posted August 28, 2009 Nope, your right, that was the suspicion at first, it was whistle left in the ram, the wrong spindle/ram combo was used. My bad. No matter, metal = spark when pinched on spindle, same BOOM!
Eric70 Posted August 28, 2009 Posted August 28, 2009 (edited) Nope, your right, that was the suspicion at first, it was whistle left in the ram, the wrong spindle/ram combo was used. My bad. No matter, metal = spark when pinched on spindle, same BOOM! C'mon as far as ramming traditional BP rockets, I thought aluminum tooling is supposed to be non-sparking? Plus one is not dealing with chlorate sensitivity. If someone had whistle mix left in the ram, that is a different story. I can see how that would cause an accident. Not trying to be a smart-aleck but I whole-heartedly agree safety is #1 but using a rawhide mallet or plastic composite hammer to ram traditional black powder rockets on aluminum or stainless steel tooling is a low-risk activity. I disagree with some folks saying they NEVER ram black powder rockets, I think that is being over-cautious and scares-off newcomers. But if that is what some feel, that is their choice and I am sure it gives them a peace of mind. To each their own. I do not doubt somebody has had a BP rocket ignite on them while ramming it but the odds of it happening is very low. Throw in static electricity or stray chemicals and a greater risk is there in my opinion. Many everyday activities pose a risk and injury or death is part of the outcome, be it walking across the street or slipping in the shower or riding in an airplane. As for the person who recently sustained injuries, I hope he is doing okay and heals fast. If this is the same person whose pictures are on pyrobin, holy smokes! Edited August 28, 2009 by Eric70
TYRONEEZEKIEL Posted August 29, 2009 Author Posted August 29, 2009 I don't even mess with whistle mix yet, since I don't even have a press. Ive diapered a gram or two together once just to see its burn characteristics, and it is just as dangerous and fast as flash IMO. I feel that I will save even touching whistle for quite some time. Static is never a problem in good ole 90% minimum humidity in Texas. ATM I am using a wooden rammer used only for BP, so the contamination is not a problem. I am actually thinking about getting some tooling. I am thinking The 2 or 3lb BP tooling from Rich wolter. But I have a few questions. 1: Has anyone had experience with these tools?2: How much performance will the extra 1/8" add in the 3 lb tooling?3: What tooling will get this effect aside from the report? WHOOOSH!
Mumbles Posted August 29, 2009 Posted August 29, 2009 Rich makes some quality tools. You won't be disappointed. I can't help with #2, but that is a core burner, or hybrid rocket.
dagabu Posted August 29, 2009 Posted August 29, 2009 I don't even mess with whistle mix yet, since I don't even have a press. Ive diapered a gram or two together once just to see its burn characteristics, and it is just as dangerous and fast as flash IMO. I feel that I will save even touching whistle for quite some time. Static is never a problem in good ole 90% minimum humidity in Texas. ATM I am using a wooden rammer used only for BP, so the contamination is not a problem. I am actually thinking about getting some tooling. I am thinking The 2 or 3lb BP tooling from Rich wolter. But I have a few questions. 1: Has anyone had experience with these tools?2: How much performance will the extra 1/8" add in the 3 lb tooling?3: What tooling will get this effect aside from the report? WHOOOSH! I just picked up Riches last 3# at PGI, I made some motors tonight (just got back in from the field) and let em go with some homemade stars I rolled Wed. WAY to freakin high for a little 2" can! I am going to a shoot tomorrow night and will strap my wife's 6" ball shell she made last week on to one (16oz.) and will let you know late Sunday how it performed. I have preferred my 4" 3# rockets for small cans and think I still will do so. The new motors are twice as long, twice the fuel and twice the cost. Go ahead and pound away all the BP rockets you want, I even shield my 3#ers. I have had a fire cracker go off in my hand when I was 10, I can still clearly remember the pain.
TYRONEEZEKIEL Posted August 29, 2009 Author Posted August 29, 2009 I appreciate the money saving advice y'all are giving me. I really hate to be "spoonfed," but this isn't something I can just go find out on my own as my pocketbook isnt ready to guess and check on several rocket tooling. So I apologize ahead of time. anyway, If the 3# will lob a 6" shell, then it may be a bit out of my league at this point. I have only made one shell, it was a 2" can from Nighthawk's tutorial that worked great, save for my lift wasnt as planned, but the shell worked and functioned correctly. I am really into just making passfire holes and adding about 20 stars or so on top of the rocket. Occasionally a comet. I have been using 7/8" ID rockets that are about 2.5" long, and they take me up to about 300+ feet, but... They are endburners. Im looking for something that will...1. Lift my star and comet headers2. Lift my 2" shells3. Be a possible conversion into bigger headers.4 Have lighting fast lift. Again, Thanks ahead of time for your help.
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