usapyro Posted October 25, 2012 Posted October 25, 2012 (edited) I just whipped this up and used my 50:50 BP/SF Fuel. It's a hummer with a bentonite nozzle. That fuel is a bit too hot for a hummer so I made the nozzle pretty big. Still was a bit too hot... LoL!!! Watch the video. It was supposed to stay in one spot... http://www.youtube.com/watch?v=41aQ-n3j2yk To make one of these you just ram a clay incriment in the middle. Drill through it, mark it's location,and then ram it full of fuel. Later you drill your nozzle into the fuel grain location. Viola... No need for thick casings on a hummer and no nozzle erosion problems!http://i48.tinypic.com/34y9vdi.png Edited October 25, 2012 by usapyro
usapyro Posted October 25, 2012 Author Posted October 25, 2012 For those curious about the takeoff... Here are the frames from it. http://i45.tinypic.com/9axnpw.png
usapyro Posted October 25, 2012 Author Posted October 25, 2012 (edited) This has given me an idea for a new firework... *Removed, Keeping design secret.* Should work... Will test tomorrow... Going to use a FAST fountain mix. If this works... I will have a slowly ascending flying fountain!!! Best case scenario... It is a new reliable flying firework that you only need to set on the ground to launch. Nothing complicated added like propellers or anything! I am going to ram the drilled incriment in the clay plug with something real slow so it doesn't fly until it hits the main grain... Don't want it to tip over with a slow launch! Unlike a Stinger or Z-Bom it will be more stable with more length to the motor. I should probably widen the internal channel a bit more so I can put the nozzles farther to the side for more rotation and stability. There only needs to be enough bentonite to steer the gasses downward for some upward thrust. I will need to create a new drillbit aligner for this out of some hardwood so that both nozzles are in the exact opposite locations at the exact same angles. Also need a centering aligner and depth restricter for the drill bit inside the tube too... Easy! Just glue a drilled wood dowel on a large drill bit. Edited October 26, 2012 by usapyro
AirCowPeacock Posted October 25, 2012 Posted October 25, 2012 Make sure you have the "splitting" nozzle real real thick. However this design has the center of gravity below the center of pressure, so your fighting normal rocket flight with this design...but we'll see how it works.
usapyro Posted October 25, 2012 Author Posted October 25, 2012 (edited) Center of gravity below the center of pressure? I don't think you have a good grasp of basic physics... Hold a pen by it's tip and let it hang downward. Try to turn it side to side. Notice how gravity tries to pull it back straight downward? Now, try to balance it on it's tip. Trying to balance it on it's tip is a normal rocket motor. I can't even hold a pen balanced on it's tip... Too hard. Finally, hold a pen in the middle and try to turn it side to side. That is how a lot of stick stabalized rockets are stabalized. With a center of gravity located at the nozzle. That is how I generally do it. The point of the stabalizing stick in the standard rocket is to move the center of gravity to or below the nozzle. The point where the rocket is being lifted. This insures that the effect of gravity upon the rockets trajectory is minimal and the rocket will maintain it's starting trajectory for the amount of time required. With slow launching end burners it's sometimes good to have the center of gravity a couple inches or so below the nozzle. This design may be so stable as to re-align itself upward when it starts to angle to the side because of the center of gravity being below the point of thrust. Think of one of those kids twist propellers or a helicopter. Edited October 25, 2012 by usapyro
AirCowPeacock Posted October 25, 2012 Posted October 25, 2012 I beleive cp = (S[x * p(x)]dx) / (S[p(x)]dx) is the proper equation. Dont forget to incoperate "flame drag". where x is distance and p(x) is pressure.
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