usapyro Posted January 6, 2012 Posted January 6, 2012 (edited) My favorite double stage rocket setup is a core burner followed by an end burner on top. You get a fast liftoff and a long duration flight. However, it has it's issues... You can't get a perfect transition from engine to engine and making two rockets is a lot more work. The transition from engine to engine in a double stage usually results in a alteration of direction of flight. I made things much easier for myself by designing a new type of rocket engine. Ill make a video of one of these sometime. I hand ram the grain end burner side down. After you have rammed and drilled the bentonite section you need to use a dowel the same size as the drill bit to make sure the BP is compacted fully in the nozzle before moving on to ramming your core burner increments. I use smaller end burner increments and ram them very hard. The core burner I don't ram quite as hard. This insures the nozzle isn't damaged or moved from ramming the core burner increments. If made correctly this rocket will seamlessly transition from a core burner to an end burner with no change in direction and no noticeable pause in speed. If your payload is too heavy the core burner should keep the momentum up good enough.http://i43.tinypic.com/ws634o.pngEdit: Another plus... If you get a Cato, most likely it will be in the air. Kinda curious what one of these would sound like with whistle fuel in the end burner grain... Edited January 6, 2012 by usapyro
dagabu Posted January 6, 2012 Posted January 6, 2012 (edited) I like!!!!! How about this? I was thinking that the addition of a cupped rammer right over the spindle followed by an increment of nozzle clay rammed by a pointed rammer with fuel on top would funnel the thrust even better. I am SO making one this weekend!!!! -dag (Yes, I know its not my drawing, it's just tongue in cheek...) Edited January 6, 2012 by dagabu
Short5 Posted January 6, 2012 Posted January 6, 2012 Okay, I reread this and an not getting how you ram the soild end grain and nozzle then ram a core burner on top of that. Wouldn't the spindle be used first for a core burner then a solid ram to set the plug and then a solid grain rammed on top? I am clearly missing something. Really neat idea by the way. Thank you for sharing.
usapyro Posted January 6, 2012 Author Posted January 6, 2012 (edited) I just launched another one a few minutes ago. These things are insane with very hot BP... Massive lifting power and a long powered cruising phase. I actually insulate the fuse with duct tape and run it near the back of the cored nozzleless grain now. The thing launches so fast you can't even see it go... I honestly just tool mine with wooden dowels and a wood drill bit at very slow speed. That is why I can tool them like I want... I just shape stuff out of hot glue and wood as needed to do totally custom designs. Re:Short5 > Dagabu is thinking of tooling from the core burner end first... What he is planning will work just fine. He is just going to use a pointed and cupped aluminum rod to shape the nozzle. V cupped rod forms the fuel over the spindle. Bentonite clay placed in tube... Then the > Pointed rod is used to finish the nozzle shape. Edited January 6, 2012 by usapyro
NightHawkInLight Posted January 6, 2012 Posted January 6, 2012 Cool! I love seeing innovation. Lets see a video. You could change the design further by instead of pressing a nozzle to separate the grains, use whistle in the top half that burns hot enough to be used without one. Of course you would want enough increments of BP pressed above the core that the whistle would not be reached until the cored section was completely expended or you would certainly blow the tube. In any case, this is a really easy new way to make what is essentially a two stage rocket. Great thinking.
usapyro Posted January 6, 2012 Author Posted January 6, 2012 (edited) Re>NightHawkInLightIs it possible to make a sally whistle that burns that hot? How exactly do you make it hotter? Different ratios or less mineral oil? (That would seem less safe...) Edited January 6, 2012 by usapyro
Potassiumchlorate Posted January 6, 2012 Posted January 6, 2012 I have actually made a similar one; I used a stinger spindle and a coreburner tube (length=10x inner diameter) and "standard" BP (if I remember correctly). No video, alas, though it worked.
NightHawkInLight Posted January 6, 2012 Posted January 6, 2012 Re>NightHawkInLightIs it possible to make a sally whistle that burns that hot? How exactly do you make it hotter? Different ratios or less mineral oil? (That would seem less safe...) Someone else will have to confirm as I have never attempted to make whistles, but most of them are nozzless end burners with a very shallow core from what I've seen. Unless I'm mistaken, that should mean the cored portion is gone quickly after the rocket leaves the pad, meaning that the solid grain burning along without a nozzle is enough to push the rocket once it's got some momentum. It would be the same situation in one of these sandwiched two stage contraptions.
usapyro Posted January 6, 2012 Author Posted January 6, 2012 I just whipped up some sally whistle with the skylighter formula a few hours ago and pressed two 2" long end burner 1" ID rockets with the stuff still slightly wet with naphtha. I also lit some completely dried stuff inside pen tubes... No way this stuff can push a end burner without a nozzle... It's only going to lift it's own weight. Whistle is quite funny when still wet... It's like a smoke strobe with a few whistles here and there! LoL!!!
usapyro Posted January 7, 2012 Author Posted January 7, 2012 Interesting design... Not sure what the point of burning two different types of grains at once is?
firebird Posted January 7, 2012 Posted January 7, 2012 I fired 2 of them in 6# size for BLM at PGI last year I have video here some where they where whistle core burner to whistle end burner.
Mumbles Posted January 7, 2012 Posted January 7, 2012 It looks to me that the grain is designed in such a way so that the nozzle can be pressed in, and avoid having to be drilled. It also allows for the tapered nozzle to be made, at least on one side.
usapyro Posted January 7, 2012 Author Posted January 7, 2012 (edited) With a inward V cupped hollow rammer on top of the whistle grain, the nozzle could be formed both directions. Do they burn it as a single stage rocket or do they ram a little BP into the nozzle afterward to create the delay between stages? Seems hazardous doing that with the whistle there... Oh wait a minute... With the angle of that upward nozzle that rocket will not develop full thrust in the top grain until the whistle grain is fully burned. Look at the grain distances! Edited January 7, 2012 by usapyro
dagabu Posted February 22, 2012 Posted February 22, 2012 With a inward V cupped hollow rammer on top of the whistle grain, the nozzle could be formed both directions. Do they burn it as a single stage rocket or do they ram a little BP into the nozzle afterward to create the delay between stages? Seems hazardous doing that with the whistle there... Oh wait a minute... With the angle of that upward nozzle that rocket will not develop full thrust in the top grain until the whistle grain is fully burned. Look at the grain distances! I don't know what will happen but I have a few pressed now with the sustainer built in above the whistle fuel and I will launch them over spring break so we will both see what happens. -dag
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