quintaped Posted December 16, 2018 Posted December 16, 2018 (edited) I've been around PGI/WPA on and off for 25 years and now I live in the middle of nowhere and can legally play around with pyro without looking over my shoulder. That in mind, I want to get some opinions on the optimum aerial salute setup for someone who wants to really launch the shell a long distance away from the mortar. For example, I'd like the shell to go off as far up and out from me. I like 500 gram salutes, so I'd want to send up something as big (give or take). My goal is sending up salutes to go off over water which is why I want maximum distance both in altitude and distance away from the mortar (me). What size mortar would you recommend? I'm guessing a two or three inch mortar but would love your advice. Everything I've ever made has been ground-based and now I want to send a few booms up into the heavens a few times per year. So what would you do? Looking for recommended mortal/shell sizes, flash quantity, and any other tips/tricks. Thank you. JR Edited December 16, 2018 by quintaped
Arthur Posted December 16, 2018 Posted December 16, 2018 A slightly longer mortar than usual for the diameter may increase the muzzle velocity a bit. It's velocity that's lost as it rises til aerodynamic drag finally stops it. Be very sure that you are breaking the device at the true top of it's flight. 2
MadMat Posted December 16, 2018 Posted December 16, 2018 I agree With Arthur! A longer mortar will help. The length of the mortar will, among a few other things determine the maximum amount of your launch charge. Adding BP to the point that it isn't all burned up before the shell leaves the mortar won't help any. Of course, faster burning BP will increase the max. amount of BP for a launch charge, but too fast and you can blow up your mortar. So, to a point, longer is better. The aerodynamics of your shell will make a big difference as well. Since there is no rifling on a mortar, the shell is going to tumble in it's flight. I guess this makes a ball shell with a smooth surface your best bet for maximum altitude. There is one idea, though it's kind of weird. I read somewhere that the dimples of a golf ball actually help in prolonging it's flight. So, maybe think golf ball on your salutes?? LOL 1
stix Posted December 19, 2018 Posted December 19, 2018 (edited) . . . It's velocity that's lost as it rises til aerodynamic drag finally stops it . . . Yep, aerodynamic drag plays a huge role. But unless you reach escape velocity, the main thing slowing it down until it stops is GRAVITY!! Edited December 19, 2018 by stix
stix Posted December 29, 2018 Posted December 29, 2018 Indeed it does Dags. According to Harry Stines "Handbook of Model Rocketry" (paraphrased): For a body in vertical flight, the drag is additive in the direction to the gravity force. I think I've been reading too much, and need to get out more 1
MadMat Posted December 29, 2018 Posted December 29, 2018 I guess the entire point is; you can't do anything about gravity (unless you are from the distant future!), but, you CAN do things to minimize aerodynamic drag 1
stix Posted December 30, 2018 Posted December 30, 2018 (edited) I guess the entire point is; you can't do anything about gravity (unless you are from the distant future!) . . . Nah Mat, I think you've got something mixed up. If I was from the distant future, (which could be true), then that would mean I have created a "Time Machine" and not an "Anti-Gravity Machine". Perhaps I created the "Anti-Gravity Machine" first, then the time machine later. From my point of view, passing through various time points (future and past), it's almost impossible to know which came first. [EDIT] Apologies for taking this thread off track. Edited December 30, 2018 by stix 1
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