Spolette for 2" can shell

[Fulmen]

I fail to see how the nosing would affect the burn rate at all, after all it's on the end, not at the burning side. What it can do is cause a delay. With an open ended spolette you'll see the flame the instant the BP burns through, with the nosing it can take some time before the pressure bursts the paper. If so, you should determine the extra delay caused by the nosing and adding this to the spolettes burn time.

 

As for burn rate it's not really that important if you get 2 or 3 seconds per inch (my old ones made from Wano 4F clocked in at 2.5s/inch) as long as you get a consistent speed.

[dynomike1]

I fail to see how the nosing would affect the burn rate at all, after all it's on the end, not at the burning side. What it can do is cause a delay. With an open ended spolette you'll see the flame the instant the BP burns through, with the nosing it can take some time before the pressure bursts the paper. If so, you should determine the extra delay caused by the nosing and adding this to the spolettes burn time.

 

As for burn rate it's not really that important if you get 2 or 3 seconds per inch (my old ones made from Wano 4F clocked in at 2.5s/inch) as long as you get a consistent speed.

Thanks Fulmen.That's what i was trying to say.

[lloyd]

Fulmen,

An extra-heavy nosing most certainly can increase the burn rate of a spolette, end-burning rocket, or candle -- until it finally burns away. Anything that increases the pressure inside a tube of BP increases its burn rate.

 

It might not be much, but it might be enough to see your 'precisely-planned' timing go out the window!

 

Normally, a nosing should not be more than two turns of 30lb kraft. That little bit of paper seldom causes much of a change.

 

But in DynoMike's case, it seems like the match/nosing delay was what caused him problems. Certainly, it takes a little time for the match to make it past the tie-off, and jet down into the spolette. Depending upon how tightly tied it was, that could amount to a substantial fraction of a second.

 

Lloyd

Edited February 8, 2016 by lloyd

[Fulmen]

Lloyd: But the nosing isn't on the burning end now is it (unless I'm missing something crucial here).

[schroedinger]

No it can't change the burning time at all, the bp that could build up pressure inside the bucket, is just the last layer and burned up at the momment when pressure build up. So there is no way it can effect the burn rate.

The bucket itself can cause a delay, depending on how good the black match can burn through the tied part. If you only use a single strand of black match it willntake longer as if you use multiple strands.

 

Venting is commonly done to make sure that the fire spit is directed into the shell and not just out.

[lloyd]

"No it can't change the burning time at all..."

------------

Yes, that's correct: Five or six turns of 70lb cannot possibly cause any 'containment' before it burns out.

 

Only a minor note: Many beginners don't know about venting buckets. (just sayin')

 

Lloyd

[pyronoob]

I use alcohol bound ERC Meal with the heavy walled NEPT tubes 1/8" per increment.....1 1/2" gets me right at 3 seconds. just another opinion

[stix]

After following this thread, and re-reading it again (apart from watching the video) this is what I've gathered about making spolettes.

• Consistent burning fuel is paramount (make a large batch just for this purpose)
• Best not to use spiral tubes (the flame could travel up the internal spiral)
• If rolling your own tubes, ensure that the paper grain is parallel with the forming tool/mandrel (for strength)
• Glue the entire strip and use quality kraft paper
• Smaller increments and stronger tubes will aid in compacting the fuel
• Use an outer former for protection, especially/mainly with thinner tubes?
• Back-drilling at the head helps 'hold' the slug into place and enables tuning in the timing
• Nosing and Venting Buckets?... I don't pretend to understand. I'm not sure about the purpose

Happy to be corrected if I've got something wrong or have mis-placed assumptions.

 

I'm assuming that 'nosing' means covering and 'tying off' the non burning end and inserting black match to ensure that fire is passed quickly. My view is that it does not, and 'should not' increase pressure in the tube and therefore affect the burn-rate, unless of couse it's a weak thin walled tube and the fire passes up the wall - not a good thing and big a failure - it's entire purpose rendered useless, and dangerous. A spolette has to be made PROPERLY!... I'm hoping to achieve that for my "own reward".

 

The reason I'm interested is that It's getting colder and wetter here, ideal for finally making a few can shells (45mm ID) and using some of the 1/4" stars I spent a lot of time making about a year ago. The "Grand Finale" and an end to a point - satisfying enough for me. I've made some very workable time fuse but would rather go 'old school' and use a spolette. Just for the fun of it!!

Edited June 2, 2016 by stix

[Mumbles]

That sounds basically right. The nosing will increase the pressure once the flame front has broken through the powder column. This is only for a fraction of a second. Blackmatch on it's own will increase the pressure anyway. The nosing secures the blackmatch in place. I still fill it pretty full anyway. Piercing the nosing helps the fire break through the nosing with ease. It also prevents the nosing from choking or delaying the blackmatch at all. There is also some concern that as the shell is spinning the fire can be sucked out of the spolette before it can ignite the shell. The blackmatch, scratching the inside of the spolette, and piercing the nosing all are suppose to help prevent this.

[DaMounty]

removed video did not work

Edited July 7, 2016 by DaMounty

[DaMounty]

1" rammed using Goex 4fg in 1/4" increments, using a .22 shell casing as scoop. I timed it under 1.5 sec. I'm not sure if a spark hit the match on the other end

Edited July 7, 2016 by DaMounty

[memo]

my home made power rammed to 1 inch gives me 2 seconds. 1.5 is fast. in the video it looked good with no sparks jumping to the black match nosing. how many have you tested ? when i am using new powder i test a minimum of 5 or more to give me a good over view. what are you using to time it ?

 

memo

[DaMounty]

I have a video software on my home laptop where you can advance video frame by frame. I'm using store bought Goex 4fG. In previous posts using this same powder at 1 inch i was getting around two seconds. The only thing I have changed is the hammer. I've switched to a raw hide dead blow...

 

DaM

[memo]

I timed it using my cell phone off of you video and got 1.97 , 2.01 , 2.00

[lloyd]

I've switched to a raw hide dead blow...

 

-0-

 

It can't be both, DaM! <G>

 

Either is fine, but if you're actually getting 1.5s/in., then I think you're not ramming it to the full density it should reach.

The mass of the hammer and its type play a role. You may have to hit it harder, or if the mass of the ramming spindle is significant, get a heavier hammer.

 

Lloyd

[DaMounty]

hmm So a raw hide mallet is not a dead blow? I learn something new everyday. Going to try a 64 oz dead blow as the raw hide is rather small.

 

DaM

[dagabu]

No, a dead blow hammer is filled with lead so it wont bounce.

[lloyd]

More importantly, it's filled with loose lead shot. A 'solid' lead fill would bounce almost as bad as rawhide.

 

DaM, the term "dead blow" doesn't mean a soft or non-marring face. It means a hammer that has zero 'rebound' when hitting the target -- all the energy is directed into the load, instead of some of it getting expended flinging the hammer back up against your striking arm.

 

Lloyd

[dagabu]

Sorry, from the phone on a job site, abreviated. ...