Questions on 8oz. Bp coreburning rocket tooling.

[Paradise]

So what is the reason one would use a bulkhead in a BP rocket??

[NeighborJ]

I only use them for testing motors. But they are stronger then delay comp. I think TR goes in depth about this in his video seminar on YouTube. I'd post the link but I'm posting with the Mobil version and am not able to.

[dagabu]

I only use them for testing motors. But they are stronger then delay comp. I think TR goes in depth about this in his video seminar on YouTube. I'd post the link but I'm posting with the Mobil version and am not able to.

 

Why so? Clay is just as frangible as BP when pressed into a puck, the only difference is that clay does not burn. Dead weight to lift and a lawn dart on the way down.

[NeighborJ]

With airfloat mill dust the strength of the bulkhead is likely equivalent but if you add large AL flake or large mesh charcoal for the delay the comp gets a little spongy. In these cases the clay bulkhead is definitely stronger. The motors have spoken to me.

[Paradise]

Once I stopped using the bulkhead it was much simpler dialing in the motor. It ended up 1 increment of win 20 atop the spindle put em at a good height. Not too high, not to low 8x flights in a row.

[dagabu]

Once I stopped using the bulkhead it was much simpler dialing in the motor. It ended up 1 increment of win 20 atop the spindle put em at a good height. Not too high, not to low 8x flights in a row.

 

+1! Timing is easier too, just hand drill to your preferred depth to dial them in.

[Paradise]

Thank you for that advice. Can and will 👌

[joeyz]

Dagabu if it is a smaller nozzled bp rocket I don't use a salute to break the stick. I've usually only taped the stick on in two places with two layers of masking tape and layed a piece of visco fuse between the two layers of tape, it separates the stick every time.

This is a pic of a 2 oz ready to fly with stick separators.IMAG0048.jpg

thats pretty slick idea neighborJ, like booster rocket seperation from space shuttle main rocket. lol

have you ever had an early seperation and a rocket turn south on you? i would think the rocket is too strong and would spin out in the air if the stick did break away early in flight, especially if it had a header (top heavy).

[NeighborJ]

Joey I only use this method of stick busting on 1# and smaller and it helps to have a header so it doesn't take off at warp speed.I also add a few more straps on the 1# motors, 4 separate ones has never failed. I plan on employing a different method for my large can shells. They have much greater forces and much greater risk of a catastrophe so I believe the only safe way to mount the stick is attached to the side of the can and use 2-3 of them. It will look something like Sputnik but the burst will definitely de-stick the rocket. I plan on video taping it to see if it effects the burst pattern.

[OldMarine]

NeighborJ, that sounds like a good idea. It may be a trick getting the sticks straight on the spiked surface but I can see it working.

[dagabu]

I'll pass on that idea, I can see a dozen issues in my minds eye with performance being at the top. The visco fuse, stick separator seems like a more viable idea.

[NeighborJ]

Yeah I guess I've reached my quota of one good idea per thread. If I could find a tape strong enough yet flammable enough to use it on a larger rocket I would but I can't find anything which satisfies both requirements. We are gonna need nc tape.

[dagabu]

Hmmm, why not? Soak virgin kraft in a saturated KNO3 solution, let dry, wipe off any crystals, apply a thin layer of paste and "tape" your stick to the rocket, let dry and insert the visco.

 

I make touch paper this way with good results.

[NeighborJ]

Sounds like another experiment is in order, it can be tied with black match top and bottom also.

Hmm? I wonder if it would hold if I just glue the stick with nc and pipe some bm from the pass fire then tie it with bm. I'd prefer the separator is lit from the top because the motor will have needed to fire before it ignites. It could be real bad if it gets triggered the other way around.

Edited August 30, 2016 by NeighborJ

[dagabu]

True that!

[Col]

I`d add a little cmc to the kno3 solution and lash the stick on while its still wet/tacky.

I`ve had good success attaching the stick to a short section of tube with the actual motor slip fitted underneath as in 2-stage rocket construction. Hot glue the header securely to the short tube and the stick will go with the header. Using a little loose bp above the delay ensures positive seperation.

Something else i`ve considered trying is routing a slot in the backside of the stick to form a sealed cavity against the tube and filling it with spanish burst or flash ignited by a hole in the tube above the delay with or without bm assistance. The stick can be securely hotglued to the tube but should be shredded when the charge ignites.

Edited November 13, 2016 by Col

[NeighborJ]

COL, I like the idea of ejecting the spent motor from a collar. Almost all of my motors are nozzleless so I'm afraid even the ejection charge won't have much to push against, though I could put a thin plug with a passfire hole at the top for larger motors. I have one motor specifically which I use most often and would benefit most, it's a 2oz whistle I use for 150g headers. It already needs a collar due to the size difference between header and motor so your idea could be adapted easily enough.

I had problems with the sticks breaking off,in flight, with some of the higher impulse motors. They have been doing well once I was told to use thinner sticks. Those motors, I would not feel comfortable trying the collar idea, at least not until that design is proven capable.

[Col]

It shouldnt be an issue as the grain tends to burn through in the middle before the sides. The top of the core ignites first so the flame front in the middle will always be slightly ahead of the sides I dont use nozzleless motors very often but it works ok for 1lb nozzled bp coreburners, whistle and strobe rockets. I use 9mm x 9mm x 1m long sticks ripped from pine boards for everything, as long as there are no knots and they pass the good old flex and bend test on all four sides they shouldn`t break in mid air

[NeighborJ]

COL, yeah I've had no problems with sticks breaking until I started pushing the limits of a few exotic fueled motors with supersonic flights. The exhaust gases were pushing out on the sticks so much that they broke, almost every time. So I tried making them larger and stronger but it made the problem worse. It was August and Dewees who suggested making the sticks smaller and thinner and...no more broken sticks. Now I use 1/4x5/16x30" sticks for almost all rockets so they have a minimal cross section facing the exhaust cone. It's these motors which I believe will not retain its stick if glued to a collar. The tiny sticks have proven to be a game changer and even though they are short, I've had very reliable trajectories with even heavy shells.

[August]

Ned has an article on fireworking.com about stick busting salutes. Basically a salute glued to the side of the motor with proper fusing. Prevents lawn darts from coming back down.

 

For sticks I highly recommend poplar. Much stronger and tougher than pine and just as light.

 

Any key to preventing sticks from breaking is making sure the stick is PERFECTLY, aligned. Not close, almost, roughly, about.... The marks left from a machined clam shell will leave perfect alignment marks. Use a pencil to make the marks a more visible and hold stick perfectly in place. Few drops of liquid super glue (professional in blue bottle, most don't stick) and you're done. Will set in a few seconds, and unlike hot glue doesn't squeeze out and block view of alignment marks, just as strong as hot glue, more aerodynamic than hot glue, and not affected by heat.

 

Don't get me wrong, I love hot glue and buy it by the case. I just have something much easier, faster, and better.

[Col]

Here`s a stick and motor attached to different points on the header.

 

 

 

[dagabu]

Ned has an article on fireworking.com about stick busting salutes. Basically a salute glued to the side of the motor with proper fusing. Prevents lawn darts from coming back down.

 

For sticks I highly recommend poplar. Much stronger and tougher than pine and just as light.

 

Any key to preventing sticks from breaking is making sure the stick is PERFECTLY, aligned. Not close, almost, roughly, about.... The marks left from a machined clam shell will leave perfect alignment marks. Use a pencil to make the marks a more visible and hold stick perfectly in place. Few drops of liquid super glue (professional in blue bottle, most don't stick) and you're done. Will set in a few seconds, and unlike hot glue doesn't squeeze out and block view of alignment marks, just as strong as hot glue, more aerodynamic than hot glue, and not affected by heat.

 

Don't get me wrong, I love hot glue and buy it by the case. I just have something much easier, faster, and better.

 

This year at PGI I was sticking a dozen rockets for Thursday nights fun when an old timer walked up to me and asked me what I was doing. I simply laid down a bead of hot glue on the end of a stick, laid the motor down on the table and laid down the stick beside it and used the table to align them both perfectly.

 

"I'll be damned" was he reply, He had been making rockets 40 years and he now uses this method, I learned it from another fireworker a few years before at PGI.

 

Now August comes along with yet another great idea for aligning sticks.

 

I love this place!

[greenlight]

I have had an 8 oz rocket kit from Wolter for a while now but haven't used it much. I did some testing with rockets with no shell and couldn't decide on fuel grinding time. The closest I got to decent and looked like it would take a shell to the required height was the standard BP milled for 20 minutes.

I see now there are better ratios for the propellant from reading online.

Does anyone have a really good fuel ratio and milling time for the propellant for these 8 oz rockets that they found.

I want to start experimenting with headings on them.