NeighborJ Posted August 26, 2016 Author Posted August 26, 2016 (edited) OK I'll try to clear this up again. The pointiest former was the first design which did not work, it had a soft side and was wore out. The second former was more obtuse and likely only worked because it didn't crush and was fresh the third variation was a 45degree ss former and it worked the best. The problem was not the angle of the former but it's malformed convergent. After the nozzle was formed I used the flat rammers. Edited August 26, 2016 by NeighborJ
dagabu Posted August 26, 2016 Posted August 26, 2016 A couple observances about the rutting issue. I turned and formed nozzles for HP rockets a couple decades ago for my team and every once in a while, a static test showed a wild spit of fire to one side or the other. Post-mortem showed a "rut" in one side of the nozzle. After long hour on the BBS (yes, I am that old) I got the answer: Pockets. Air pockets in the cast nozzles and a pocket of soft graphite in the graphite rod I was turning. Clay is no different, if you use a rammer to form a nozzle, it has to be uniform. Flat nipple and flat rammer make a flat disk, drill the hole and you get a uniform choke. The gas will flow HORRIBLY but it will flow uniformly. I made a lot of wooden rammers too, they all worked to an extent but you have to be able to keep it uniform to keep it working. I am still making that offer for an aluminum rammer, J.
NeighborJ Posted August 26, 2016 Author Posted August 26, 2016 Too late Dag I made all ss tooling for this one. Heavy but works awesome.
Maserface Posted August 26, 2016 Posted August 26, 2016 (edited) I get what you are saying but using an angled rammer will cause you to use more force to get the same compaction BUT the hole in the drift makes for a smaller surface making up for that lost compaction. It is true that in order to be competitive, you can't throw in extra rammers and lose that money or time and yes, I understand that it does not present a problem on the face of it (see what I did there?) but you cannot put the same force on that comp without adding a lot more force on the walls. A flat face will give better compaction, and with J speaking of using a really steep angle of 60°, 80% of the actual force is being pressed out to the walls and not down. A flat rammer is almost a necessity at this point. So if I turn a rammer, with a steep angle (120deg total) and no hole, I should be able to rupture tubes with 20% of the pressure that a flat faced rammer would take? Edited August 26, 2016 by Maserface
NeighborJ Posted August 26, 2016 Author Posted August 26, 2016 No, come on now. He is saying that you will need to increase the pressure of the press to get the same compaction as a flat rammer. At least this is how I read it and it makes perfect sense to me. If you Robin Hood an arrow it splits the side because the head pushes mostly out on the walls of the first arrow. If it only pushed strait it would drive the first arrow farther in the target or collapse under the strain.
Maserface Posted August 26, 2016 Posted August 26, 2016 Ok, so what he means is that 80% of the actual force is going into the tube walls, and the remaining 20% goes down. But with a flat rammer 0% of the actual for goes into the tube s and 100% goes down?
NeighborJ Posted August 26, 2016 Author Posted August 26, 2016 That sounds about right but with the steep spindle it will compress the clay near the walls more than the center so it would end up leaving the core soft and vulnerable to rutting even if you could manage to compress the clay 5x it's normal amount.
Livingston Posted November 5, 2016 Posted November 5, 2016 Bp rockets are not my forte but I've used plenty of skinny spindles and I know I'm chimming in late but I know with that there tooling you have can make sum loud and powerful whistling rockets. Benny based fuel is very forgiving noisy and powerful!! You can easily make a tube support with sum pvc pipe and hose clamps. I use one for my 3lb tubes. I believe there's an article out there describing how you can make one. My buddy makes 6lb Sally whistle motors on a universal tooling using a tube support made out of what I just mention. It just seems like more work making BP rockets then whistle https://youtu.be/LCYNgcQrEGc Hers a little 1 pounder skinny spindle rocket that I made a minutes.
NeighborJ Posted November 5, 2016 Author Posted November 5, 2016 Nice rocket Livingston, it has been a while since I've messed with that particular spindle and I can say that it was a learning experience. Most of my whistles are sali and I can't remember if I've ever tried that spindle with Benny. I do like the design but only for nozzleless motors, BP, whistle, and zippers. The whistles are by far my favorite and when catylized and without a header they tend to go supersonic, at least with the 4# version from this thread. The nozzle motors needed too much tweaking to make work consistently and would be more suited to the longer fatter version which Caleb sells. Not that I've put much time in searching, but certain tube sizes don't match the prospective pvc pipe supports so I haven't made a support for this short motor yet. When I do, it will entail pouring epoxy in a mold around a lubricated tube.
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