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This is a collection of posts between Dj and myself and DJ and several other people all related to the way DJ makes his "Nozzleless Rockets" and a few comments on BP in general.

For the fuel, standard 75/15/10 BP, must be ball milled. You want it FAST, but don't wet it in  the mill or press it in any way before ramming. See earlier post on specifics.

Ramming procedure, must be done in small increments. When done correctly you should have  about 8 ramming cycles to fill the tube to within 3/8" from the top with fuel. See earlier post on the specifics.

End plug on top, not necessary! If you pack your fuel to within 3/8" of the top of your rocket  tube you will have enough fuel packed above the core "thrust portion" of the rocket motor to prevent blow through (almost an inch). About 1/3 rd of this will be consumed "I think" during  initial thrust burn, leaving over 1/2" of packed fuel to prevent blow through and a small time  time delay before burn through.

These motors when made correctly can and will go over 600 feet <----- Again I'm being  modest here. The average amount of fuel in one of these motors is 7 grams, and I have been  lifting payloads of 50 + grams to altitudes of 150 feet. And that is just about perfect for a film  can shell!!!

 Spindle length can be easily changed to adjust thrust and lift ability, I found that a good  working range is 50 to 60 percent of tube length. The longer the spindle the more risk of a  cato, but once you get your fuel and core length dialed in is when these motors really fly. The  above tooling dimensions is almost fool proof, meaning almost any good "milled meal"  powder will make them work without a cato, assuming you followed all instructions and your  BP mill powder aint garbage. If your milled BP powder is fast enough to make this motor cato,

you got some damn good powder bud, in that case you will need to tone it down some.

For the spindle I use a 3/32" ark welding rod, with the flux knocked off. I then sand it smooth  with emery cloth while I have it spinning in a drill, I give it a slight taper when sanding to aid in removal from the rammed motor. The spindle/spindles I use are not fixed into the base, they  just sit in the hole I drilled dead center of the 3/8" dowel that sticks up from the base. After  ramming I lift the motor and spindle from the base and then use a pair of pliers to twist and  pull the spindle out, if the spindle has been sanded properly it comes out with little effort. I  made my spindle and base this way so it would be easy to experiment with different spindle  lengths without having to make a different base for each spindle. My next base will have a  locking set screw to lock the spindle in the height that I want before ramming (maybe?).

The fuel..................

 Hello,
 I think it's time for me to mention what kind of fuel (of course BP!) you will need for a successful "nozzle less BP motor". <---  BTW, anyone got an idea what to shorten this down to, maybe NLBP motor or something even shorter?

 Anyway it's just the standard BP formula (75/15/10), and it WILL  need to be ball milled. The type of charcoal you use may vary your  results, so keep notes on what charcoal you use when testing these motors. I have used commercial air float C from Skylighter, and mesquite natural charcoal from the store that I milled to air float, and Rande has had success with another I forget what kind though. I  don't think the type of charcoal you use will affect the fuel so much as to keep your rockets from flying, but it may affect the power and performance. This is one of the things I hope to learn from all of you, I'm sure every one will try different things and get different results. So please post anything of significance when you get these flying.

  The amount of time you ball mill your powder is also important, but basically you want the fastest damn BP powder you can make  WITHOUT wetting it in the mill or pressing and corning it afterwards. You want just light fluffy mill meal powder, if your one  of those people that add water to their powder in the mill and end  up with lumps and rock hard chunks after milling, Don't add the  water. You want your BP fast, but not pressed in any way. If you add  water when milling you are pressing your powder slightly in the  mill, and this can cause problems when ramming your fuel in the rocket tube. Powder that has already been pressed (even slightly) is  much harder to re-press and get a solid consistent type grain of  fuel that you need in BP rockets.

  If dust is a problem when ramming, you can wet your "mill meal"  <-------(that's what I call my BP right out of the mill) with about  2 or 3 percent water, mix it well (should be the consistency of dry  Bisquick mix) then run it through a window screen or similar (it should darn near fall through on it's own), onto a newspaper to dry.What you will end up with is very soft and light BP grains that will crumble to dust easily, this is much less dusty to ram and will not  affect powder compaction.  And if your lucky, and your BP is so fast that your rockets  CATO, and if you followed all other instructions properly. You will  need to slow your powder down in small increments, I do this by  adding a small percent of oil (.5 to 2 percent usually). This helps  keep dust down and slows the powder slightly, and I "think" it helps
hold the powder together when it's rammed or pressed. The oil is an  option that some disagree with, but it works for me. You could just mill the powder for less time to slow it down, or add a little extra charcoal..... it's up to you. <----- more things to experiment with. I could give you a more detailed list on why I prefer the oil but not in this letter.

 Just a little info. that is real important when ramming or pressing rocket motors. I learned this at WWB in a class that was  held on making rockets. Well I should say that I new the proper  procedure but I never "really" under stood the reasoning behind it, and sometimes went about ramming in a time saving manner. If your one of those rocket people that like to save time in the ramming process, you'll probably benefit from this info. It may be the reason for allot of the cato's you get when you  think you've done  everything else just right.

  When ramming or pressing it is VERY important to only add enough  powder in each cycle to increase the height of compressed fuel by NO  MORE than the ID of the rocket tube you are working with. So if your working on a motor tube that has a 1/2" ID, you would want the amount of powder your adding during one ramming cycle to be "no  more" (and less is even better) than what it takes to bring the COMPACTED powder level up 1/2" after ramming. This is simple to do, just measure how far your rammer is sticking out of the tube after one ramming cycle. Then measure it again after your next ramming  cycle, if the increase in rod length sticking out of the tube is  MORE than the tubes inner dia., you need to cut back on how much powder your adding. If it is less that's fine, because less is  better,  just means you'll have a couple of more ramming cycles to go  through to complete a motor.

 I used to think that by re-inforcing the tube with a sleeve and  hitting harder with the hammer or by using a bigger hammer <---  (mechanics approach) I would be able to get away with larger powder  increments and save time by reducing the amount of ramming cycles  needed to complete a motor. WRONG!!  And it wasn't until recently that I understood why, I mean I've been doing it right for some time  now, but I'd been doing it with kind of a blind faith. And stuck to
it when I found that it reduced the amount of cato's I had been  getting and never new why.   When you add too much powder in the tube at one time and start to
ram or press it, the powder starts to compress just under the ram tool. And as it does this the powder wants to expand sideways until  it "bites or grips" the tube just like a clay plug or nozzle does,  it then forms a type of "plug" that is supported by the looser  powder under it. The looser powder under this plug will absorb the
shock from additional blows or pressure from the ramming tool but  will not be compressed like the powder above it. You end up with a  rocket that has unevenly compressed powder, and that can cause big  problems!

 Hope this info. helps, and it is one of the things you will HAVE  TO DO RIGHT to get my nozzle less motors to work well without  blowing up. I had a hell of a  time figuring out why 1/3 rd of the  rockets I was making long ago were BLOWING UP when I sat down and mass produced 20 or 30 of them at a time. The fuel was all from the same batch and the scoop size and ramming increments were all the  same, but 1/3 rd of my rockets were blowing up. When I switched to
smaller powder increments this problem all but vanished. Hmmm, live  and learn........
 

 Stay green
          DJ.

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