usapyro Posted October 17, 2012 Posted October 17, 2012 (edited) http://i48.tinypic.com/2e4x9bd.png I just got a very cool idea for a double stage rocket... 1. Initially we will start off with a nozzleless core burner to get things moving up to a good altitude. 2. We will then blow off the nozzle-less core burner with granulated BP and initiate the intermission spin up section. This will have two side offset nozzles put in just like a stinger. (Except a stinger has just one.) 3. Finally the end stage will blast off on it's own with a high rate of spin giving it gyroscopic stabilization! Now, the only potential problem there could be is the spin up section... The spin up nozzles could effect the rockets direction of flight a bit. Worst case scenario you have a high speed perfectly straight trajectory rocket heading for the ground at high velocity!!! If there is issues maybe I can try my old non-erosion stinger technique... I drill the spin nozzles angled through bentonite which keeps nozzle erosion down and the pressure buildup for both nozzles is steady! http://i48.tinypic.com/wwbyhy.png Anyone got any other ideas on how to get a 2nd stage to a stabilizing high spin rate? Maybe put some angled holes at the end of the first stage to kick off the start of the rotation. Edited October 17, 2012 by usapyro
usapyro Posted October 17, 2012 Author Posted October 17, 2012 (edited) Here is plan B if the first doesn't work... Actually, going to try this one first because it's much simpler and all I need to do is go drill one of my motors and tape it to another one! Just two stinger holes near the end of the first stage. Two endburners this time... Two stabilizer sticks with a wire between them to prevent spread during spin-up! bottom ends of sticks meet and are taped together. Edit: Oh, and just as a note... I attached my stages together with a couple wraps of paper tape. The tape is 2/3rds over the lower stage so that when they blow apart none is left sticking to the upper stage.http://i49.tinypic.com/i3c2zr.png Edited October 17, 2012 by usapyro
WonderBoy Posted October 17, 2012 Posted October 17, 2012 There is some discussion on the last page of this thread http://www.amateurpyro.com/forums/topic/5967-new-rocket-competition/page__st__60__hl__+stage%20+stinger?do=findComment&comment=95128 about two stage rockets with stinger missile second stages.
usapyro Posted October 17, 2012 Author Posted October 17, 2012 That is a pretty interesting and cool way to do things, however... What I am trying to do is get some serious altitude out of the second rocket. If I can impart enough spin on it it will manage a stable flight without needing to sacrifice power to generate it's own spin... Wait a minute here!!! I GOT IT! I can generate a light spin on the first stage using small angled fins... And place two more on the second stage! By the time the second rocket fires the spin achieved should be plenty... And I can place a couple additional small angled low friction fins on the final stage to insure completion of a fully stable flight!!!
usapyro Posted October 17, 2012 Author Posted October 17, 2012 Viola... Now this is SO MUCH better than my initial idea... OMG! To do a spin stabilized second stage rocket all that should be needed is a dual stick stabilized start with initial spin-up angled fins... Then small low friction fins on the second stage to give enough rotation for continued stability through the second stage! http://i46.tinypic.com/2efuh54.png
nater Posted October 17, 2012 Posted October 17, 2012 I hope you are planning on lighting those in a desert with nobody or anything else around for quite some distance,
dagabu Posted October 17, 2012 Posted October 17, 2012 Viola... Now this is SO MUCH better than my initial idea... OMG! To do a spin stabilized second stage rocket all that should be needed is a dual stick stabilized start with initial spin-up angled fins... Then small low friction fins on the second stage to give enough rotation for continued stability through the second stage! I have to ask though, why make the rocket spin at all if you are looking for more height? Gyroscopic stabilization takes a lot of energy, spin stabilized rockets only go about 1/2 the distance of a straight finned rocket so to improve on your design for the furthest possible flight, you will need to get rid of all the extra weight and only have three small fins on the TOP motor only. Don't get me wrong, I like all the designs and have added one of them to my build schedule for this winter, not for performance sake but because it looks really fun! Good luck and post some gosh-darn-video already! -dag
usapyro Posted October 17, 2012 Author Posted October 17, 2012 (edited) It's rather hard to upload videos on 56k... I do live 30 miles from the nearest town right now! Hard to rip a wifi connection good enough to upload video files in town... I don't have much luck with straight finned rockets... LoL! They love to fly crazily... Spin stabilized is my only way to get an individual rocket to fly without a stick successfully! My angled nozzle rockets and stinger's were pretty random though last year... Jeeze... Talk about random flight direction establishment... Even when tube launched! They would fly out the tube... Randomly pick a direction, then head that way full speed and straight!!! Edited October 17, 2012 by usapyro
usapyro Posted October 21, 2012 Author Posted October 21, 2012 (edited) This design here with three angled spin stabilizing fins is a lot of fun... I omitted the lower fins in the first test. First the launch angle was a little off and it was heading up at a sixty degree angle... Then it flew around erratically for a couple seconds once the stages separated. Finally, it made a horizontal beeline to the left accelerating back to full speed flying perfectly straight like a dart horizontally at a 15 degree downward angle. Another person watching commented that the rocket seemed to have decided to go bear hunting in the orchard midway through it's flight... LoL!!! I need to do a smoother separation and the bottom fins really are required to get things spinning! At least I know the rocket flies properly once it gets spinning fast enough. Now I just have to remove the random new flight plan at the stage separation. http://i47.tinypic.com/f3w9iv.png Edited October 21, 2012 by usapyro
usapyro Posted October 21, 2012 Author Posted October 21, 2012 (edited) This design will be the next attempt... Dual stinger nozzles late first stage then angled fins second stage to keep the rotation speed up. Get enough rotation out of those side nozzles and the second stage might generate some lift before ignition like a propeller! I'm using 50:50 Willow Meal/Powdered Sugar Fuel (66/34/+2) for all of these tests.http://i45.tinypic.com/16k0xsn.png Edited October 21, 2012 by usapyro
dagabu Posted October 21, 2012 Posted October 21, 2012 You won't like the effect much, the spin will make the whole thing unstable and will tear itself apart. -dag
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