Neds Nozzleless Rocket Motor

[Jandabuilders]

When making nozzleless rocket fuel, it appears that Ned does this with a premixed batch of fuel that he had labeled as such. I am confused as to how he makes this. And what makes it hotter then normal and what mesh size it is. In reading the articles on Skylighter, it reads as though I should make a batch of BP, then instead of any binder, wet it down with Lacquer thinner and mineral oil only, then granulate and screen with something like a 20 mesh. Is this correct? Would commercial air float charcoal from Skylighter be sufficient or would I be required to make it with something like white pine or willow charcoal? (Which I plan to do anyway) This is specifically related to his cohete type bottle rocket videos. Thanks

[Elisabeth]

For a nozzleless BP driver you want to use hot BP (75/15/10). Don't need any special charcoal. Screen mixing should work so long as all your chems are very finely powdered. I ball mill mine.

[Jandabuilders]

Thanks for the reply. I’m on attempt number four. The first one, I didn’t mill the kno3 enough. The bare rocket motor didn’t even leave the stand. The second attempt, I didn’t screen granulate. The bare rocket motor lifted nicely but when the payload was added it didn’t achieve full height and fell to the ground before the motor was finished burning. Attempt number three, ball milled everything, screen mixed through a 100 mesh screen, wet mixed with 2% mineral oil and screen granulated. That produced a good rocket flight with a payload but it still started to fall before the heading ignited. For my fourth attempt, I’ve made some white pine charcoal and ball mulled everything. Same screen mixing and granulating as before. It’s drying now and I’ll make a motor tomorrow. I’ve also made some willow charcoal to test. We shall see...

[Mumbles]

For nozzleless rockets, the hotter you can make the fuel the better. There are several ways to achieve hot fuel, but it sounds like you're well on your way. Finely ground or milled materials are key. Milled together isn't required, but it sure helps. Oil slows things down a bit, but helps keep dust down and helps with compaction.

 

Just visiting have some tips that work well for him recently on using water in lieu of oil in this thread https://www.amateurpyro.com/forums/topic/13335-core-burning-rocket-question/

 

Are you hand ramming or pressing the rockets?

[Jandabuilders]

I’m hand framing the rockets with Caleb’s Cohete kit. I am adhering to the formula of 1/2 the size of the tube ID for each fuel increment. So far this is the first project in my venture. Aside from making a ball mill, making charcoal and experimenting with BP formula. I am trying to follow the exact steps in Ned video on these rockets.

[BetICouldMake1]

The short, fat spindle on those makes them pretty forgiving. Like mumbles said, the hotter the fuel the better. Commerical airfloat will work, but it won't have the power of a hotter charcoal. I love my 1 lb cohete spindle. Fast and easy little BP rockets and it also makes great whistle rockets.

[Jandabuilders]

Ok. I think I need to go back to the basics. None of the rockets are flying very fast, although the one made with the white pine charcoal made it higher then the rest. I think I may need to mill down the KNO3 before weighing. That might be my problem. I bought it from sky lighter and it’s pretty corse. This very first batch of BP I made, I didn’t mill it down and that didn’t do anything but burn. No thrust or lift. I quickly realized I needed to mill it all and screen mix it through a 100 mesh screen so I milled some of that down with a coffee grinder. That was a while ago and I have since built a ball mill. I’ve just been throwing the raw unmilled kno3 into the mill with the other ingredients but the ratios can’t be the same because I’m weighing out UNMILLED kno3 to the other MILLED ingredients. The more I think about this, the more it makes sense. So tonight, I’m milling a handful of kno3 only. Then I’ll mill some of the willow charcoal I made. Then I’ll weigh out some BP and try it again...One plus to all of this is that while I’m testing out the rocket motors, It also gives me the ability to experiment with different headings. The salute headings are fun and all but I have really enjoyed playing with the different combinations of BP charges in the heading. I made some with crushed chalk for this last run, although that too was a fail! But that’s for another thread..Oh well, back to the drawing board...and forum boards

 

On another note, who is behind wichitabuggywhip? I heard this site mentioned in one of Neds videos and it seems to be a wealth of info. Seems like a pretty great site to me.

[Mumbles]

wichitabuggywhip is run by Danny Creagan. He's a former PGI board member, but I haven't heard much from him recently. Great site.

[BetICouldMake1]

Whether or not your kno3 is milled won't affect its weight. It will affect volume, but that doesn't matter if you're weighing out your comp. My guess is that your ingredients might not be fine enough in addition to not using very reactive charcoal.

[Jandabuilders]

Thanks for the reply. I guess that does make sense now that you put it that way. 75 grams of unmilled chems will still be 75 grams once milled. Either way, Ive got some milled kno3 now so Ill combine all ingredients together in milled form. My motor went out on the ball mill so Ill screen mix them through a 70 mesh screen then finish it all through a 100 mesh screen.

 

In looking at the video, it seems as though Ned used ABOUT half the volume of lacquer thinner to the total volume of composition in order to wet the mixture. I tried that on the last batch and it got it pretty wet. Even soupy, but the thinner evaporated pretty fast so I was able to continually mix the comp as it eventually dried into a putty ball for granulating. I have noticed that once the granulated composition is dry, it can still easily crumble down to a dust. Is that normal? There is no binder, only +2% mineral oil.

Edited September 7, 2019 by Jandabuilders

[Jandabuilders]

Success! Used Willow charcoal. Ball milled kno3 and then screen mixed everything. Worked great! I’m stoked!

[BetICouldMake1]

Yep. The granulation process for rocket fuel is just designed to keep the dust down, you want the granules soft so they compact well when rammed/pressed. Keep in mind the mineral oil will also slow down your propellant somewhat. Alternatively you could just dampen the fuel to a brown sugar consistency with water and run through a screen. Or simply wet your mill dust with 1/2-1% water and press that way. In any case, congrats on your success!