3lb nozzle-less coreburners and different delays

[leedrill]

hi guys

ive been thinking about trying to run some nozzless bp motors on my wolter 3lb coreburner spindle.

now my question is i know there is not a lot of people whom regularly build 3lb motors on here but am hoping for an idea of redline with, no nozzle,nept tubes,and ballmilled paulownia char..

 

im thinking after playing around with a nozzle and different bp that 75/15/10 will still be too hot for the spindle without a nozzle. But i do not run oil, wax, or soap, in my bp motors so am unsure if adding 2 to 3% would help me be able to run as hot as i can make it would like some idea from anyone experienced in 3lb motors or any help at all

 

ive been thinking to myself 70/20/10 with 2 to 3% oil or what ever will be fine but not sure so any input will help

 

thanks

[WonderBoy]

lee,

What are the dimensions of your spindle? I think you should be fine using your normal BP in a nozzle-less configuration. IIRC I made this nozzle-less motor on "cored BP" tooling with commercial charcoal BP, plus 25% benz whistle, and it hardly made it off the pad! I have never used oil in my BP motors.

 

http://youtu.be/S3OuRLPjqD8

 

 

 

WB

[leedrill]

my spindle is about 190mm long and about half the id of the motor tube wide at the base so about 7.4" long and 1/2" at the base wide do you recall the spindle on the motor in that vid

[psyco_1322]

The wax helps the fuel stick together and ram into a solid grain. If you are using 3% wax, you should be able to use as hot of fuel as you can make. I would suggest not using oil, it can inhibit the fuel from sticking in the tube, especially if you are hand ramming.

[mabuse00]

If I may interpose a question here:

Have you guys ever directly compared wax and oil?

 

I was using oil for my BP motors for some time, but I found when I scratch the grain surface, I can grind of material more easily than without oil. I found that I really had stronger grains with wet riced or redgum riced BP.

The gain in reliability was caused by slowing down the fuel, I was fooled by that.

So, at least in my experience, (paraffin-) oil is not the answer.

[leedrill]

i have never gotten a rammed motor to work well so i now press everything and i guess 75/15/10/3 will be my starting point thanks guys

 

 

would love to know the dimensions on that motor WB and how you prepare the howler fuel is sounded pretty cool for just 25% whistle fuel i would of thought that any other fuel would eliminate the whistle

Edited September 29, 2013 by leedrill

[WonderBoy]

I have found that one of the keys to making high powered rockets, especially ones that are rammed, is to use small increments. I would routinely hand ram all of my 1lb and 3lb BP motors, and they are very consistent and powerful workhorse motors.

 

I don't have the spindle here, but IIRC it is 1/2 ID at the base and a bit shorter than yours, about 165mm long.

 

I only used the BP:whistle mix around the spindle, then pressed straight benzoate whistle as the delay. The long open tube is what makes the howling effect.

 

 

WB

[Juiceh]

i have never gotten a rammed motor to work well so i now press everything and i guess 75/15/10/3 will be my starting point thanks guys

Try it without wax or oil and press it to 10,000psi on the fuel grain.

[ddewees]

So how did these turn out? I'm thinking about heading down the same road, and was hoping to glean some info.

 

Thanks.

[leedrill]

with the foster method on the tubes and the hottest bp i can make on a wolter coreburner tooling no adding wak to the fuel i will be lifting 6" shells and 5" cans with these motors quite well will need some longer sticks though 4" shells act like they are not weighing down the motor at all just slowing the launch a little

[ddewees]

Had good success with 75/15/10 + 5% wax on nozzleless core burners today. May cut back on the wax until they pop.

[leedrill]

i have done no wax on the tubes and no wax in the fuel and they dont pop with nept tubes and the bp is crazy hot

[ddewees]

Good to know, thanks.

 

I love the wax, if only because it makes everything so clean. I rammed three motors today, and didn't even have to wash my hands after.

[leedrill]

i cant disagree with the clean part but it does reduce power dramatically

[hindsight]

Felt the need to revive this thread because of a series of CATO's I have been experiencing with 3lb nozzleless rockets using Wolter's BP rocket spindle, commercial FFG, and waxed 1" NEPT'S. The rockets are pressed within Wolter's clamshell to just over 9000psi finished off with a bentonite bulkhead. The grain appears solid. I'm using a total of 200 grams (which seems a bit generous) of BP, in 8.5 gram increments, pressing a couple increments above the spindle. Despite access to large quantities of commercial BP, the next step will be to make some screen mix BP (awaiting Steve's lead/antimony media for the ball mill) if the CATO's continue. Humiliating and demoralizing. Any suggestions?

 

 

 

 

Edited to add that they are bottom-fused and lit from one day to two weeks after manufacture, and the humidity is unchanged during that period.

Edited July 9, 2014 by hindsight

[nater]

I do not make nozzleless BP rockets, but with traditional BP rockets, larger ones need a slower fuel than smaller ones to prevent a CATO. Commercial FFG is also pretty hard, while 9000 psi on the comp is pressing hard, I want to say that Steve LaDuke once said it takes 10-12k to properly compress commercial BP Edited July 9, 2014 by nater

[dagabu]

I agree with Nate about the FFG, the commercial grains really never compress enough to close the spaces between them. I tried it a few times and then ball milled it, pressed a rocket and it flew fine.

 

I suggest making some and trying it, I think you will find it works better.

[jessoman]

Hey Hindsight,

I also, would definitely say it is the commercial granules. I like the ideas of dag with milling it. If you are going to that extent, I would be making my own fuel. Are you not making your own BP to reduce risk and save time?

Ideas:

-Since you have that gorgeous clam shell support. Up the pressure in an attempt to make 'what you got work'.

-May I ask what your dwell times are? You could try extending them.

-What delay are you using? Perhaps you could try and use a delay which consolidates really nice, like TR's/winokur's famous win39j.

-You are using a hydraulic press yeh?

 

If you still have problems after making your own BP. I have some ideas.

 

Kind regards,

Jess

[dagabu]

​Another idea is to add some oil (1%) to the BP to get it to consolidate better, dwell time should be several seconds and up the pressure to 12k as others have mentioned.

[hindsight]

You gentlemen are so very reliable. Since you are unanimous in the opinion that it is the use of commercial granules that is causing the problem, that's where my attention will be focused.

 

Nater, I also wondered whether it was a matter of the fuel being too fast for a 3lb rocket. And 9000psi seemed enough, especially since the grain is hard and uniform. But I will try pressing at higher force. Presumably, my 3.8cm (1.5inch) thick by 15cm (6inch) wide steel press plate will not bend too much at the higher pressures you recommend. As always, I appreciate your input, particularly information you pass along from the masters with whom you associate.

 

dagabu, jessoman seems to be of the opinion that you are suggesting re-millng the commercial FFG. Or were you just saying to make some new BP. I will go ahead and make some scratch mix 75-15-10 and try that. (The ball mill is complete but I am awaiting the arrival of lead balls from the supplier by the same name). If it is too slow, faster BP will be the next step. Also if you were talking about adding oil to the granulated commercial BP, and not to the new or re-milled BP, what technique should be used to do that? I suspect that is not what you meant, though. If the new BP does not help, I will add oil to it. Already tried to increase dwell time to a few seconds previously, without improvement. Good of you to help, again.

 

jessoman, The reasons for using the commercial FFG are multiple. As stated, I have access to a stockpile of it. So convenience, time (as you said) and expense are influences. And you are spot on when you mention safety. The fewer times I have to screen BP or empty a ball-mill the better. Then there is the factor of constancy of formulation and performance. You also figured correctly when guessed my use of an hydraulic press. Again, dwell times were increased without benefit. Increasing pressing force using the clamshell does make it harder to unscrew the retaining swing-bolts, presumably due to expansion of the motor tube. Please explain to me the effect of delay comp on CATO rate, if that's what you were trying to tell me. I may be asking you for the help you offered if my failures continue, thanks.

[dagabu]

Hindsight,

 

1.) Add the oil (just about any kind you have) using a spray bottle with the widest pattern you have to finely disperse the oil. Yes, right on the 2F you have then use a longer dwell and more pressure.

 

2.) No, the BP is not too fast for the tube, whistle burns much faster and with more power.

 

3.) Yes, ball mill the 2F to a fine powder, *whet it and rice it. It will pack much nicer in your tubes.

 

​4.) There is no need to ball mill the BP for a rocket, mill each of the three ingredients separately and screen them together, whet them and rice the meal. Once dry, press as normal.

 

5.) Yes, the more pressure you put on the tube, the more pressure you will have on the clam shell and the bolts. Believe it or not, oiling the bolts will increase their life span and make it easier to open the clam shell.

 

 

*Several different theories on that one, water and dextrin, alcohol and ricing, many ways to skin that cat.

[hindsight]

Only had time to press one 3lb rocket to 12000psi (and greater) with a few seconds dwell time per increment of commercial FFG. As predicted, it took the strength of a bear to open the clamshell screws after pressing and I may have slightly deformed the top of the tube near the bulkhead, so the test may be invalid and therefore will have to be repeated. The rocket went up 5 meters before it ruptured in a blast. There was a rent beginning about 5cm from the bottom along the side to the top of the NEPT. Made 4lbs of 75-15-10 screen mix with commercial airfloat which was alcohol-granulated. When it is dry, I'll try that as rocket fuel.

[hindsight]

Okay, dagabu, a lot of things to try. Somehow missed your last post before I posted above. I am not sure which to try first, but I will spray oil on the commercial FFG and press again at high pressure/long dwell. The screen mix as mentioned above is drying. If oiling the bolts will help, consider that done. Thanks for helping me try to get these things up in the air.

[jessoman]

Great stuff hindsight. As your in the middle of tests I won't comment, but will watch this space eagerly.

I will PM you a youtube link (which you may/probably have seen) regarding the use of a delay composition, it's a TR presentation. It discusses the use of a delay. I won't post it in APC as it may not be allowed to be on youtube and I want it to stay there . I believe this may help if you are CATO'ing 5 meters in flight.
I would love to see a video of the CATO's. PM me the link if you don't want to go public. It might help come to a conclusion.

I have a few other ideas, but you have a damn few ideas to work through first by Master. Dagabu and measly me.

 

Cheers,

Jess

[hindsight]

jessoman, Thank you for the link to Meister Rebenklau's video lecture. He recommended Winokur 39J for two to three increments above the spindle top because he felt that it compressed very solidly, reinforcing the benefit of the top "plug" of clay. Interestingly, he does not ball mill his BP for rockets and uses 80 mesh charcoal. He also uses many small increments when pressing (he never rams with a mallet). I will continue to incorporate whatever information you provide into my plans.

Edited July 10, 2014 by hindsight