Mumbles Posted May 20, 2016 Share Posted May 20, 2016 Wait in #16 you say a endburner fell back to earth, and in #19 you say it was nozzleless. If that both is true, no wonder, such a setup won't produce any reasonable thrust. Mumbles why do you say there is such thing as too hot bp in rocketry. Your propellant always has to match the rest of your setup. Of course you can use the fastet propellant as you want, but if your tube just can't handle the pressure, it doesn't help at all. Same with the old and new NEPT tubes, both good quality, but the new ones just can't handle as much as the old ones (sadly). Well sure, if you're using inferior materials then it's possible. I don't really consider than a valid exception though. It's like saying your BP is too hot to be used as lift, but you're using a paper towel tube as the mortar. Link to comment Share on other sites More sharing options...
schroedinger Posted May 20, 2016 Share Posted May 20, 2016 Well sure, if you're using inferior materials then it's possible. I don't really consider than a valid exception though. It's like saying your BP is too hot to be used as lift, but you're using a paper towel tube as the mortar. Now i want to see a nozzled rocket, with hot bp on one of calebs long spindle tools. You say that works. Link to comment Share on other sites More sharing options...
Maserface Posted May 20, 2016 Share Posted May 20, 2016 Now i want to see a nozzled rocket, with hot bp on one of calebs long spindle tools. You say that works.Lots of us have done it- https://youtu.be/x5yPbp4tlw0 1 Link to comment Share on other sites More sharing options...
Merlin Posted May 20, 2016 Author Share Posted May 20, 2016 (edited) Thanks for all the comments. Success on the third attempt! Nozzled endburner 8oz with BP made with commercial airfloat. Lifted off very much like a Estes motor and went completely out of sight (day time) motor burned 10 to 12 seconds. Hotter BP would probably have worked but I am pleased with its performance. It flew into the wind and stuck into the ground at 250 yards- I want the debris to land on my property! Now after a few repeats I will get it scaled similar to Estes D or E and use them in models. Yes I know the ejection charge will have to be added. Thinking of using streamers rather than parachutes cause at that altitude the wind would allow the model to drift far far away. A video cam on the rocket would be interesting.By the way that rocket video above was incredibly fast. Hard to believe a BP rocket can lift that much weight so quickly! That takes talent. I would never attempt to put a shell on a rocket- the timing must be difficult. Edited May 20, 2016 by Merlin Link to comment Share on other sites More sharing options...
Mumbles Posted May 21, 2016 Share Posted May 21, 2016 Merlin you say you use hot 75/15/10 +2% mineral oil in a 8 oz nozzled rocket. That fuel is commonly used for nozzleless rockets. In nozzled rockets it can work, but also can be to strong. What you experience sounds to me like your motor is blowing up at the end of the thrust phase, when the burning surface reaches it's max area.This can have several reasons. As the tube survives until the end of the thrust phase the quality should be ok. If you don't wax your tubes, this is quite likely to solve the problem.If you allready wax your tubes, you will need to decrease the burn speed of your powder (decrease the ammount of kno3 in the fuel) or use a tool with a larger exhaust hole (more complicated if you don't have a lathe). I would try to make a batch of 14/3/1 No such thing. If you think your BP is too hot, I will guarantee you're not compressing hard enough or the tubes suck. I apologize, I read your post incorrectly. I thought you had said that black powder could be too hot for nozzleless rockets. Just to be clear here is where I stand. Nozzle with a core: Needs a slower fuel than straight BP. Typically 60:30:10, but can be a little hotter. Nozzleless with a core: As hot of BP as possible works. Will accommodate BP + Whistle, or straight whistle Nozzle, no/minimal core (end burner): Also will accommodate full strength BP, or even potentially whistle. Nozzleless, no core: Basically requires whistle if not stronger. Link to comment Share on other sites More sharing options...
schroedinger Posted May 21, 2016 Share Posted May 21, 2016 (edited) @mumbles then we stand at the same point. @maserface yes i know that vid of S. F., that video and his work to get that motor working, inspired me to to try it to (well it works but i had a llt of cato, so never lifted anything but sand with it and didn't want to shorten a spindle for that), but bp milled for 2h worked quite reliable, a shame that i have nearly no more NEPT tubes. But anyway he made the rocket on a la Duke BP tooling, not an extra long core. Edited May 21, 2016 by schroedinger Link to comment Share on other sites More sharing options...
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