Peret Posted October 20, 2012 Posted October 20, 2012 We've all had our "oops" shells, make it more rewarding when things finally work right. I mainly put the pics up to show a close-up of what a 3 inch shell burst looks like, and how big it is. You don't get many opportunities to see one so close. That was a plastic shell with 3 layers of gummed tape, broken with BP on rice hulls and no booster.
bob Posted October 20, 2012 Posted October 20, 2012 (edited) I dont know about Grams, but i use 1oz. 2Fg. with no problems. When i get my ball mill that might change. that's about 28 grams if I'm doing my math right I was told that I was not using a enough lift but there is some thing I'm got getting cause I thought that 3 to 4 seconds up was what you wanted? and that a 6 to 8 second flight up and down would get you that 3 to 4 seconds to apex and 5.5 grams got me a 6.25 second flight so I thought that was what I wanted (I know it was 6.25 second flight in the tests but when I shot the shell it was .47 seconds). thanks for your help Edited October 20, 2012 by bob
dan999ification Posted October 20, 2012 Posted October 20, 2012 terminal velocity, and proppelled flight are different, its going up faster than its coming down, ive used as little as 8 percent lift but for peace of mind 25g never fails if the shell can survive it, there are members as above that use an ounce of good powder, you get a louder lift so the shell needs to break well or it looks pewny compared to the heavy lift. Dan.
Mumbles Posted October 22, 2012 Posted October 22, 2012 An ounce is close to 28g yes. It's safer to have it too high than going off on the ground. I've always had a hell of a time with 3" ball shells in getting the lift just right. There seems to be critical mass with regard to lift. 5g may plop a shell out, but 7g could easily lift it properly. With these smaller shells I typically will use at least 10% by mass of the shell of a finer grain BP resembling 2Fg just to make sure they're up in the air. Compressing/restraining the lift slightly or using a liftcup may help. It seems odd that a test shell would work fine with the same amount of BP though. Weather can affect things, but this would be bizarre without some major temperature swing.
dynomike1 Posted October 23, 2012 Posted October 23, 2012 I may be in the wrong place but i didn't want to start another thread. Is there a book of video that shows like a picture of a certain burst and says that i used this formula and i built this shell this way. i see a shell burst but don't know what it is.David Blesers book has some in it for instance Saturn shells. Seems like the more i look the more i get confused. Since this is our busy season all i have had time to do is make 2 C-6 shells and shoot them. I might be getting ahead of my self.
Peret Posted October 24, 2012 Posted October 24, 2012 There are lots of videos in the "Aerial Shell Competition" thread, and pretty much all of them say what type of stars they use, along with details like shell size and type and burst.
bob Posted October 24, 2012 Posted October 24, 2012 I shot of another shell last night and well it did go up good and high but it was far from a round brake.I did a lot of burnishing and it looked pretty good not as good as Alengco's but still pretty good. It had 12 layers of pasting, 1/4 inch TT stars, 5 to 1 black powder grass seed ratio, and 8.5 grams lift, it was coming down when it broke but very little. bob
bob Posted October 28, 2012 Posted October 28, 2012 shot another shell last night using 15 grams of lift it could have had just a little bit less lift but not much at all it was almost stopped it broke ok the every thing worked it just wasn't really nice and round but it was better then my last one to bad I didn't get a picture of it bob
dynomike1 Posted October 30, 2012 Posted October 30, 2012 Since my chemicals are restricted till i upgrademy Lic. i will have to use my imagination Can some one tell me how to attach a Tourbillion to a shell. I cant figure it out with out the break tearing it up.
Mumbles Posted October 31, 2012 Posted October 31, 2012 A tourbillion isn't normally attached to a shell. If I were going to however, I'd wrap a string around it a few times around the center of the tube and tie a stout knot, and then attach that to the lift loop of a shell. It should allow it to spin on the way up. Epoxy over the string can ensure that it will be securely attached. More often a ring of tourbillions are placed inside the shell.
dynomike1 Posted October 31, 2012 Posted October 31, 2012 I guess the one i saw was inside. I just kinda figured the break would break the wings.
Mumbles Posted October 31, 2012 Posted October 31, 2012 Ah yeah. They're are two things commonly called tourbillions, which literally means whirl-wind. One is a ground based spinning device with wings. These can actually get fairly intricate, occasionally being made with 4 tubes total. You could probably attach this to the outside of a shell if you really wanted The other is much more simplistic, but the effect is still quite nice. It's a tube charged with a fairly strong propellant, usually a BP base with additives for sparks. A single hole is placed in the side of the tube toward one end. Two holes on opposite ends of the tube, also 180 degrees apart can increase the spinning frequency if needed by providing two flame fronts. When it burns it results in the insert spinning around in the air after being ejected from the shell burst. These may also be called whirlwinds, or spinners or something like that in an attempt to differentiate them from the ground based item.
dynomike1 Posted November 1, 2012 Posted November 1, 2012 I just remembered they also make one like a disk w/ the same effect.
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