Loosing comet effects

[NeighborJ]

I normally make rocket headers so comet effects are not what I normally use but this year I went with cyl shell and mortars for the 4th. I lost nearly 50% of the comets during lift so it is clear to me that this is my biggest problem area.

 

How do you guys keep your comets attached?

[lloyd]

I think the more salient question is: "How did you attach yours?"

 

Ordinary 'paste-wrap' is the way it's correctly done. The comet is sometimes first wrapped around its sides (only) with about 2-turns of light kraft (about 30lb) fully 'broken-in' with paste. The paper is stripped of most of its paste, then applied directly to the bare surface of the comet, where it's allowed to dry thoroughly. It will shrink, and affix itself strongly to almost any comet type.

 

That is then attached to the shell top with a generous pasting-in of more paper extending at least 2/3 (to all the way) up the comet's sides, and in a pattern about 2-3 comets'-worth in diameter onto the body of the shell. Sometimes practitioners will hot-melt affix the comet to the shell first, in order to make everything easier to handle.

 

If the bottom of the comet is not profiled to match the surface of the shell, it helps to use a heavier 'puddle' of hot melt to take up the gaps, but just don't let the glue 'squish-out' past the edges of the comet, or it will interfere with the pasting pattern.

 

Often, a sheet of glassine will be lightly affixed over the top of the comet, just to help prevent errant sparks from igniting it prematurely. This is usually necessary for shells shot from racks, but not so important for those hand-loaded one-at-a-time in single guns.

 

LLoyd

[NeighborJ]

Hmm, the comets were attached almost as you described. The exception being I used masking tape to fireproof the sides and put a string under the blob of hot melt to tie the QM firmly to the top of the comet. The tape could be the issue but I also would add that there was no pasted layers of broken paper on these shells, they were solely held together using dry paper wraps and spiking. This does not provide an adequately rigid surface to attach the comet to. Is there a solution without pasteing?

[lloyd]

Were these cylinder shells with spolettes for timing? If so, one solution is to make the spolette itself also become the rising effect.

 

The Japanese press rising effects into paper tubes, and tie them on a rope 'tail' for a different sort of 'look' for a rising effect.

 

But if the shells were made by rinfasciature, there's just nothing on the shell to which you can properly affix a rising comet, unless you add a trailing tail effect.

 

Lloyd

[NeighborJ]

Thanks Lloyd, I like the Japanese solution. I have some kevlar string which is purposed for nosecone leaders in amateur rocketry, I'll try knotting the end, pressing it in a serpent tube with comp then tie it to the fuse bucket.

 

The spollete idea would work also, I may need to use a 1/2" tube for adequate spark production. I only had 1 day to build these shells so they had time fuse and rinf construction.

 

I'll play around with these ideas over the summer to see what works best.

[Mumbles]

I would say your problem is related entirely to the surface you're attaching it to. 50% is probably a commendable success rate. The surface you're applying the comet to is likely too flexible. It's possible that the outer most paper is tearing or scorching or coming loose upon lift and this is causing you to lose the comets.

 

In a typical rinfasciature shell, the shell is spiked, then wrapped in paper, then spiked again. The strings (which should be wet with paste) can then be additionally protected with a couple of turns of additional paper spiked on with maybe 4-8 verticals depending on the size of a shell, which is not something I see. Without this final light spiking, the outer wrap may be coming off after the quickmatch hits the bucket and potentially tears and or blasts it apart.

 

You can also apply a pasted layer to the outermost spiking. One or two layers is all that is needed to fireproof the string, and it'll be dry before you know it especially in the sun or a drying box. This would provide a secure and flatter surface to attach comets to.

 

Also, for what it's worth, exposed comets should light fine from the lift gases. The extra quickmatch to the comet probably is overkill. Tying a few strands of blackmatch over a primed surface is also very reliable. I've done masking tape in a pinch, but prefer well wetted gummed tape or proper pasted paper. Pasted paper is the best option, but in a time crunch like a build-on-site club environment gummed tape is also passable, and blends in with the shell better. The last point is pretty tangential, but if a person is willing to take the time to make a shell look clean and presentable before firing, just imagine the care they took in constructing it.