Arthur Posted April 15, 2016 Share Posted April 15, 2016 ...Are you sure about that Arthur?... Well the info came from Ron Lancaster's book with several worked examples. As for imperial vs metric either can be used with 1% accuracy with ease so as long as you are accurate it matters little which you use. 1% or better is reasonable for good and repeatable results. Link to comment Share on other sites More sharing options...
stix Posted April 16, 2016 Share Posted April 16, 2016 ...Well the info came from Ron Lancaster's book with several worked examples. Arthur, perhaps you have mis-interpreted Lancaster's description. Maybe he's just pointing out that larger motors will require more compaction which is difficult the bigger you go - therefore resulting in lower density and faster burn rates which increases the possibility of cato. From memory the density (sg) of black powder is around 1.8grams per cubic centimeter (water = 1). Anyway, regardless of the fuel type, maintaining the same fuel density is paramount in order to evaluate the motors performance. You certainly want to pack as much fuel into the motor as possible. My opinion is that you need faster burning fuel the bigger you go. Your statement "Small rockets need fast powder but bigger rockets (in terms of bore diameter) need to use progressively slower powder" if taken to it's absurd conclusion would suggest that black powder in a large rocket (the bigger the better) is capable of reaching the moon. There is some basic fundamentals of your statement that don't make sense to me and it's very important to get this right, not just for me but for others reading this post in the future. Do you have the text from Ron Lancaster's the book that explains this in detail. I'd be very interested to discuss it. Cheers. Link to comment Share on other sites More sharing options...
DavidF Posted April 16, 2016 Share Posted April 16, 2016 I don't see anything incorrect in Arthur's last post. It is commonly said that smaller rockets can tolerate faster propellants than large rockets. I do think this applies moreso to coreburners though. I can say with some confidence that there are very few cases where black powder is compacted to a density of 1.8g/cc in a rocket made by an amateur like one of (most of) us. A propellant grain pressed to that density is like stone. It can be done though. When folks make BP pucks, the BP is generally moistened. To achieve a very high density like +1.7g/cc in a rocket motor is doable this way. Link to comment Share on other sites More sharing options...
lloyd Posted April 16, 2016 Share Posted April 16, 2016 Yes... 'solid' pressed powder ready to be corned runs about 1.7g/cc. And -- that is "dead-pressed" in a rigid mold, which is an unlikely condition in a rocket motor. The tube will subside under pressing force enough to virtually guarantee you cannot reach a dead-pressed density in a paper tube. LLoyd Link to comment Share on other sites More sharing options...
stix Posted April 17, 2016 Share Posted April 17, 2016 Sorry, my bad memory. 1.7g/cc at best then. Which I imagine would be harder to achieve the bigger you go. Does that mean it would be better to alter the fuel composition to make it burn slower? Link to comment Share on other sites More sharing options...
Xzanth Posted April 20, 2016 Author Share Posted April 20, 2016 https://youtu.be/pShdC8Qmn3M 1 Link to comment Share on other sites More sharing options...
Blackthumb Posted April 20, 2016 Share Posted April 20, 2016 Depending on where you live, some woods are not readily available.......I use nothing but newspaper for my charcoal....Also, everyone has access to wine corks....natural, not synthetic....makes very fast BP. 1 Link to comment Share on other sites More sharing options...
OldMarine Posted April 20, 2016 Share Posted April 20, 2016 I wonder how many wine corks would be required for a pound of BP? I'd probably have to give up pyro to pay for a liver transplant! Link to comment Share on other sites More sharing options...
OldMarine Posted April 20, 2016 Share Posted April 20, 2016 https://youtu.be/pShdC8Qmn3M Excellent! Link to comment Share on other sites More sharing options...
Xzanth Posted April 20, 2016 Author Share Posted April 20, 2016 Still had a lot of flight left before ejection charge...... Need a good delay formula. Readyyyyyyy... Go and marine that was the cedar you sent me. And that was one of my bigger rockets I made xD Link to comment Share on other sites More sharing options...
OldMarine Posted April 20, 2016 Share Posted April 20, 2016 (edited) Did you find some cedar pet bedding?Best thing for a TLUD.Just use some crappy powder for delay if you have nothing else. Seems most people use Winokur 39 as delay but I haven't tried it. Edited April 20, 2016 by OldMarine Link to comment Share on other sites More sharing options...
Xzanth Posted April 20, 2016 Author Share Posted April 20, 2016 You sente cedar lol... Link to comment Share on other sites More sharing options...
Xzanth Posted April 20, 2016 Author Share Posted April 20, 2016 I'll just go 45/45/10 for delay. Not trying to make sparks and all that. Link to comment Share on other sites More sharing options...
schroedinger Posted April 20, 2016 Share Posted April 20, 2016 I would recommend whistle/ti for delay or zinc (spreader) Link to comment Share on other sites More sharing options...
Xzanth Posted April 20, 2016 Author Share Posted April 20, 2016 Don't know what those are. So I'll stick with model rocketry. These aren't fireworks Link to comment Share on other sites More sharing options...
carbonhalo Posted April 20, 2016 Share Posted April 20, 2016 I'd run the other way next time.... so there is no sun in the background Link to comment Share on other sites More sharing options...
lloyd Posted April 21, 2016 Share Posted April 21, 2016 You have to understand that he takes the WORST vids in the world! He ALWAYS JITTERS, because he won't buy a tripod. He ALWAYS picks the worst vantage point. He ALWAYS produces the worst videos he can muster... and I think it's intentional! OTOH, his rockets ARE working, now! (still a bit weakly, Xzanth... if you want payloads) LLoyd Link to comment Share on other sites More sharing options...
Xzanth Posted April 21, 2016 Author Share Posted April 21, 2016 (edited) ALWAYS the worst information from you. Thanks everyone else Edited April 21, 2016 by Xzanth Link to comment Share on other sites More sharing options...
stix Posted April 21, 2016 Share Posted April 21, 2016 That last one was much better Xzanth - I'm sure they'll get even better the more you progress. To me it's not that important about the video quality, but it's also not that hard to consider a better vantage point and try to be a bit more steady. If you can. I thought I was the one that always had the worst information . There's nothing wrong with "constructive criticism" and Lloyd did say "(still a bit weakly, Xzanth... if you want payloads)" - which I agree with. Anyway, perhaps there could be a section titled "APC's worst videos" - I've got a couple of contenders myself. Link to comment Share on other sites More sharing options...
lloyd Posted April 21, 2016 Share Posted April 21, 2016 Xzanth,If you meant me (worst information), I'll be more than happy to keep my opinions to myself, with regards to your fireworks. You're a grown up boy, and can make your own judgements about them, based on your decades of experience making them. You asked for opinions. If you don't want them anymore -- That's fine, too; either way. LLoyd Link to comment Share on other sites More sharing options...
FlaMtnBkr Posted April 21, 2016 Share Posted April 21, 2016 Sounded to me like he was just ribbing you back Lloyd. I hope all those late hours in the shop making large piles of swarf by yourself isn't turning you into a cranky curmudgeon! <G> One of those, and one of these, just to be clear: >;^) I was going to throw an 'old' in there but thought that might be going too far. Link to comment Share on other sites More sharing options...
lloyd Posted April 21, 2016 Share Posted April 21, 2016 He may have been... (I hope he was). But I have no particular investment in it either way. And that's all I meant by my response. It wasn't to pick a fight -- just to say, "If you don't want the help, I'll refrain. No hurt feelings." Nah... I'm not more curmudgeonly than I was before... but I _am_ sequestered on an Army base right now, and that somewhat affects my general view of life! <G> LLoyd Link to comment Share on other sites More sharing options...
schroedinger Posted April 21, 2016 Share Posted April 21, 2016 Oh, and I thought you where satirical because of all that uppercase words. Link to comment Share on other sites More sharing options...
lloyd Posted April 21, 2016 Share Posted April 21, 2016 Me? SATIRICAL? Link to comment Share on other sites More sharing options...
FlaMtnBkr Posted April 22, 2016 Share Posted April 22, 2016 Anyone that would turn down your advise would obviously have a long ways to go in pyro. Keep the info coming because even if someone thinks they know better, the rest of us can still learn from it and appreciate it. Link to comment Share on other sites More sharing options...
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