Gottagotomoz Posted August 17, 2007 Posted August 17, 2007 I'm about to make my first BP rockets. My first rockets will be 1/4 ID, then when I feel comfortable enough with that, I will make 1/2's and 5/8's. I would like to make end burners because they seem relatively simple, however I am unsure of the ratios I should use to make my BP. I would be using balsa wood, so it may burn too fast. What ratios would be best? The standard 75:15:10? Or add more charcoal/less sulfur? 75:20:5? Also, how long should I mill for? 2-3 hours?
willowmp Posted August 17, 2007 Posted August 17, 2007 end-burning they are very easy and quick to make. they are very enjoyable too.edit: sorry mumbles i was just stating imo
Mumbles Posted August 17, 2007 Posted August 17, 2007 Wow, what a great reply. I know so much more now. Anyway, start with normal 75:15:10. It is fairly standard with end burners. From there you can modify them to suit your purposes. Without tooling, core burners can be relatively difficult to make, as the core is hard to get straight by hand without some sort of drillpress. Balsa is indeed pretty fast, but end burners require a fast powder. Ball mill as long as you would normally for good BP. If you find they're blowing the nozzle out, or catoing, add 5% charcoal, and try again.
frogy Posted August 17, 2007 Posted August 17, 2007 I use 75:15:10 White Pine Charcoal for my end burners... But the general rule of thumb:Standard Meal: 75:15:10End Burners: 60:10:10 (75:12.5:12.5) or standard meal powderCore Burners: 60:30:10 60:10:10 and 75:15:10 are basically the same You will normally see these referred to as 6:1:1 and 6:3:1 Remember more charcoal = slower burning... If I was you I wouldn't waste any balsa on rockets.... Pine is less suitable for lift, yet better for rockets because the pine charcoal leaves a good trail of gold sparks in meal... For ball milling... With a rock tumbler 3 hours is probably decent for rocket grade powder, but for end burners you want a little bit of a stronger powder, so the more the better... With a good mill like a Sponenburg, it only takes a few hours to make grade A meal...
Gottagotomoz Posted August 17, 2007 Author Posted August 17, 2007 Thanks guys. The only charcoal I have is balsa. Unless of course I can use some of the BBQ charcoal. No, not the briquettes. The bag says 100% natural lump charcoal. I don't know if it will work, but if that'll be better, it would really be helpful. Thanks for all your help once again guys. Edit: The brands name is Royal Oak Charcoal. Heres a pic:Royal Oak
Mumbles Posted August 17, 2007 Posted August 17, 2007 That charcoal might actually work. I use Cowboy brand all the time for BP, lift, burst, etc.
frogy Posted August 17, 2007 Posted August 17, 2007 Balsa is great for end burners... But if I had balsa and pine I would chose pine over balsa for drivers... If you can get pine, try to get white pine because it doesn't have as much sap as yellow pine... I can see that you don't really want to wait 2 hours to make different charcoal... and thats fine Likes mumbles said... End burner powder needs to be fast, so balsa is fine...
Gottagotomoz Posted August 18, 2007 Author Posted August 18, 2007 Also, will a 1/8th drill bit be sufficient for nozzles? I know it's all a bit of trial and error, but I want to be as close on the first try as possible.
frogy Posted August 18, 2007 Posted August 18, 2007 Uhh... I'd say thats too big... For my 3/8" rockets I use a 3/32" bit and it works perfectly... So for a 1/4" I'd aim for a 3/32" bit too... It is trial and error, but somehow I got it right on the first try =)
qwezxc12 Posted August 18, 2007 Posted August 18, 2007 Yeah, for the size you're building 1/8" is too big. I used a 1/8" nozzle diameter for my 3/4" ID (1 lb.) 75:15:10 endburners. For a boost, I sometimes added +10% -350 mesh Al flake. Then I opened up the nozzle to 3/16" dia. to prevent CATOs.
frogy Posted August 18, 2007 Posted August 18, 2007 I add 5% ~20 mesh Mg to my 3/8" rockets with a 3/32" hole and they haven't CATO'd yet... I just made 6 rockets w\ 25:5 bp(75:15:10):mg(about 20 mesh)and they all worked fine... with 3/32" nozzle
moonshot Posted August 19, 2007 Posted August 19, 2007 Ok. In my opinion this is what you should do. EXPERIMENT! Make an end burning 1/4" ID rocket motor with your balsa charcoal BP. Tape a stick to it, light it and see what happens. It's either going to fly or die. If it sits there and fizzes like a fountain your propellant is most likely too slow. On the other hand if it goes off with a loud report and your neighbors dogs start barking you know your powders a bit too hot! (I know,I've had both happen to me). This may sound weird but the second result is the best because you now know your propellant is powerful enough. If your rocket flies congratulations! you got it right the first time and you can fine tune the design for consistency . Since you stated that these will be your first attempts at making BP rockets I would stick to trying your 75/15/10 mix first and not add any metals to the mix. If you end up blowing out tubes or nozzle/end plugs, try slowing your propellant down by adding charcoal to the mix. I like 70/25/5. Rockets are one of the hardest devices to perfect because you have to do a lot of fabrication IE.Tubes propellant, headers, sticks. But ultimately you have to build it, light the fuse and see what happens! Here is a pic of a handmade 1/4" ID 2 1/4" long core burner with nozzle and the tooling I built to ram the motors.http://i107.photobucket.com/albums/m314/di...07/S3011374.jpg
Recommended Posts