Problem with shell fuse lighting once fired from mortar

[Raceman17]

Hello everyone. I need some suggestions on what I am doing wrong. I have been making 3" shells and I can not get a reliable ignition of the shell fuse once the mortar fires. I am using visco Cannon fuse timed to three seconds with masking tape. I am using two fuses per shell that have been hot glued to both sides of the shell as it passes through the shell casing. Both fuses are cut at a 45 degree angle with a razor. The fuses are sticking out of the shell no more than 3/16" past the taping. I am using small paper Cups that have been cut down to hold the lift charge. The fuses are probably 1/2" from the top of the lift charge once assembled.

 

I have just started making Cedar charcoal for the black powder and I can definitely tell a difference between homemade and commercial airfloat. I am using 17 grams of lift for shells that weight 140-170 grams. The shells have no more than 1/4" clearance when the shells is put in the mortar pushed to one side. So roughly 1/8" all the way around the shell.

 

I have made and fired 10 shells over the past two days and two of the shells did not light. I was also using the Cedar charcoal black powder with these shells.

 

So what am I doing wrong? Should the fuses be sitting in the lift change? Do the fuses need to be primed with something prior to putting the lift cup on?

Is my shell clearance to the mortar to tight? These things sound like a cannon when they fire off. Thank you for any suggestions you can offer.

[OldMarine]

I would use spolletes if you don't have time fuse. If you don't want to go that route you can try a dab of NC lacquer and then a dip in rough powder on the fire taking end of your visco. I've only just started dabbling in aerial shells since I'm in love with rockets and headings right now but I've been working on my spollette skills since time fuse is now an unobtanium and as you've found, visco is unreliable and not made for the job.

[Raceman17]

Thanks for the suggestions. So I am assuming the NC lacquer us made with ping pong balls and acetone? How long does it take the lacquer and BP mix to dry before finishing building the shell?

[OldMarine]

I use smokeless powder for my lacquer now but have used PP balls. If you make a small batch of lacquer mixed with powder, paint it on your fuse and then dust with more powder it will dry as fast as nail polish.

[pyrokid]

Another simpler option is a BP slurry with ~5% dextrin as a binder. After dipping the fuse in the slurry I dip it in granular BP to give a rough surface. The BP in the slurry is unmilled 75-15-10 which works well in my experience.

[Raceman17]

OK. So reading what you wrote. Get ping pong ball and acetone. Cut the ball up and put in small glass jar. Add a few ounces of acetone and let the ball disolve. After that add some BP to the NC mix or just dust the fuse once wet with lacquer? Sorry for all the questions. Just trying to get all the directions! Thanks

[Raceman17]

Another simpler option is a BP slurry with ~5% dextrin as a binder. After dipping the fuse in the slurry I dip it in granular BP to give a rough surface. The BP in the slurry is unmilled 75-15-10 which works well in my experience.

So this slurry is just water and basic BP with more dextrin? What consistency is the slurry? Can the slurry be stored and used in a few days or it a one time mix and use application?

Edited August 8, 2016 by Raceman17

[pyrokid]

Consistency is a matter of personal preference. I prefer for it to be thin enough to conform to the shape of the fuse but thick enough to allow for a sufficient amount to be deposited onto the fuse while holding the granulated BP.

 

In principle it could be stored for a few days but I usually just make it as needed. It's easier to clean up this way and I don't have to worry about readjusting the water content or the dextrin spoiling, if that even is a concern.

[BlueComet24]

Priming the ends of your fuses (I recommend inside and outside the shell) really helps the fuse to not only take fire from the lift, but also to retain its powder. The powder in Chinese visco falls out easily, and this can cause the fuse to not catch fire. I personally use BP+dextrin slurry and wet it to approximately the consistency of pancake batter. It really doesn't matter much how thick or thin it is, as long as it coats the fuse well.

[Raceman17]

Thanks everyone for the suggestions. It sounds like I need to be priming the fuses. I will try the suggestions and post back the results. Is an 1/8" gape two tight of a fit for the shell to mortar clearance?

 

I'm also having an issue trying to tie all my mortars together to a single fuse once they are loaded into the rack. I have a 5 shot rack that I am testing with. I'm using homemade blackmatch/quick match from the lift cup to the top of the mortar. I have taped a 4 inch piece of cracking fuse on the ends of each quick match fuse and then taped the ends of each cracking fuses to a longer piece of Cracking fuse as the main fuse. I am using cheap masking tape for the connections. It appears that the blast from the mortars are ripping some of the fuse connections apart. I am going to stop by the u haul store and get a roll of their packing tape and try that. Is this the preferred method of connection or am I missing something?

[Raceman17]

So an update:

I made some nc lacquer with a ping pong ball and acetone and that seems to have helped. I have made three shells over the past two evenings and had zero failures. I also stopped by the u haul store and picked up there packing tape. It also seemed to do the trick when tieing multiple shells together.

So I have one last question in this. What is the preferred method to tie the shells together? Using quick match with a piece of visco taped to the end of it; do you leave a few inches of quick match hanging out the end of the mortar draped over the side of the rack or do you tie everything together flush with the top of the mortar tube? Thanks everyone who helped with my issue.

[OldMarine]

Leave your QM looped over the top of the mortar or it may well take the visco with it when it goes up. The first inch or so of QM doesn't usually pop and if you leave your visco pointing down into the mortar it will get ripped upward. I only use scotch tape to connect my visco to my QM leaders because it basically vaporizes upon ignition of the fuse releasing it from the leader.

[Raceman17]

Leave your QM looped over the top of the mortar or it may well take the visco with it when it goes up. The first inch or so of QM doesn't usually pop and if you leave your visco pointing down into the mortar it will get ripped upward. I only use scotch tape to connect my visco to my QM leaders because it basically vaporizes upon ignition of the fuse releasing it from the leader.

That makes sense. I had also thought about adding a few pieces of scotch tape to hold the qm leader and visco leader closer and secured to the rack. I know in the videos of my shells leaving the tube you can see the qm paper being blown out of the mortar with a lot of speed. I've had it rip the next fused connection apart. That's why I read around and heard of the u haul tape used in tieing fuses together.

Thanks

[FlaMtnBkr]

If you use NC lacquer you want to add some powdered BP to it so it's like a thick batter. If you use only NC, especially with PP balls, it can create a fire block that doesn't pass fire. It's still a good idea to dredge the fuse in small granules of BP to give a rough surface that catches fire more easily. You can also add a little aluminum powder to the laquer which will make a really hot fire ball when passing flame to the inside of the shell.

[Raceman17]

The process I was using was to take the lacquer and coat the bottom of the fuse area on the shell. The consistency is like a light pancake syrup. Then I would take the still wet lacquered area and press it into some granulated black powder. Will this process work reliably or should I add the BP to the lacquer first. Do you use just regular black powder mix before it's granulated in the lacquer?

[OldMarine]

I use mill dust in my lacquer slurry then dip it in granulated powder so it's nice and rough.

[dynomike1]

Another simpler option is a BP slurry with ~5% dextrin as a binder. After dipping the fuse in the slurry I dip it in granular BP to give a rough surface. The BP in the slurry is unmilled 75-15-10 which works well in my experience.

That's what i use with mine. Never had a problem. With that being said i don't even cross match time fuse. A little slurry and slow burning bp.

[Raceman17]

I had two more successful launches this evening using the NC lacquer and dipping the fuse area into granulated BP. Is anybody using visco fuel for smaller shells or are yall using the 1/4" timed fuse? I tried to upload the video from my phone but then program said my files were wrong.

 

Also, how often do you test out your shells. My entire family owns 40 acres of land so I'm kinda surrounded by family all around. I've kinda been Shooting something off every evening right at dark. Does anybody else test frequently?