6 replies to this topic

[Sparky]

Hi all

 

I got an opportunity to fire about 20 shells I've been working on over the last few months. Unfortunately the camera wasn't coping well with focus and the operator zoomed in by accident so most of the shots are not really worth sharing. However there are some I'd like some feedback on and have posed on you tube.

 

I had a few shells not break hard enough, a few where I hadn't primed the stars well enough and only some lit. My biggest issue was with the 4 inch shells and not getting enough height on the shell due to the poor lift. I know my BP isn't red hot but it fires the 3 inch shells perfectly well. I think it may be due to the poorer fit in the tube as it seems quite a lot of a gap around it. Some suggestions on how I can help there would be much appreciated. 

 

Anyway here are a few of the clearer ones with descriptions. Please excuse the shrieking family members in the background :-) I would appreciate some comments, constructive criticism etc. 

 

The last clip shows what can happen when you get a composition slightly wrong. I made was should have been a fairly vigorous waterfall type composition but as a fountain. It was unconfined in a thick walled 3/4 inch tube. It just goes to show you that even 250 mesh Al + 40 mesh grit Al and 10 mesh flakes of Al with Potassium Percholorate can explode. It was a lesson for me as I assumed you really need dark al to get a salute affect.

 

Enjoy....

 

http://www.youtube.c...0XPnQA4TqzCr6OW

 

 

I should mention that all my shells use KP coated rice crispies which I boost with granulated benzolift which I prefer making to flash and is easier to handle when loading a shell. For paper shells with some good pasting I find it works brilliantly as a booster although sometimes I could have used a little more. Fear of blowing blind is the main reason but now I'm getting reliable priming working I can be less cautious.

Edited by Sparky, 13 January 2013 - 05:46 PM.

[megabusa]

Nice one Sparky - I enjoyed that !

 

I loved the fountain LOL - I had one last year that went like that, it was containing some small granite stars to add colour in the plume, I thought I'd try it to see what it was like. 'Loud' was the best description. The kids thought it was funny, at a safe distance of sourse.

 

This GFN, I had problems with my Gold Willows not getting enough height. I probably got complacent with my lift, as it is usually quite good & I didn't test that particular batch for speed ( I also possibly didn't mill it as long ....).

The shells only reached about 120 feet, with 12mm Slow Gold in them you can guess what the fallout was like !

 

I prime all my stars except Tiger Tail. I just use BP dust with +7% Si, it's rare if I get stars blowing bind.

 

The burst I use is either willow BP for smaller shells, or willow BP coated rice krispies for the larger shells. works for me.

 

 

How much of a gap do you have on the 4" when in the tube ?

 

 

We'll have to compare notes at the next AGM !

 

Cheers,

 

Phil.

[Sparky]

Hi Phil,

 

I suspect there is some variation in my BP as some were better than others but I had some commercial BP and although it was noticeably quicker (just the sound of the shell firing made that obvious) the height was still a little low. I would have expected a better height with a 400g shell and 40g of commercial BP. I'm using 100mm paper tubes and the paper hemis are 90mm which even after 3 or 4 layers of 3 strip pasting (so essentially 6 or 8 layers of paper) I'm no where near a snug fit. I'd like to avoid getting involved with 10 layers of pasting as I'm getting pretty nice breaks when I get the amount of boost just right and I doubt they will be a tight fit even then.

 

So given I know my BP isn't quite as hot as it could my understanding is that a good fit for the shell will help mitigate this. I also make sure I build pretty solid lift cups to help confine it a little, I'm using willow charcoal for my lift BP but have also got hold of paulownia which I mainly use for break. I've also got some vine and straw charcoal to try, it might be interesting to see if they are any quicker.

 

Oh and I use a small cheese grater to granulate the damp BP for lift. The granules are similar to what you get pushing it through a 20 mesh (1mm ish) but they tend to be longer like grains of rice.

 

A couple of my lower breaking shells also dropped some nice fallout into the pine trees, never looks good does it 

 

All my later and better primed stars lit fine so I'm happy I've got the priming right. Like you I use Bp with silicon but also a variation on Fencepost prime.

 

One thing I know I need to work on is either making a star roller or at least getting my stars cut more square so they break more evenly and burn for a more similar duration. I will definitely be braver with some extra boosting too but I have to be honest I don't like shells that break too hard and fast I think it makes the effect less dense. Just personal preference I guess.

[Karl Mitchell-Shead]

Some stunning shells Sparky, good hard breaks and the hang time on the Strobe was as good as any Yung Feng shell I have used in shows! Well done!

 

Please take it as constructive criticism but 100mm shells should ideally be placed at least 100m from your spectators (According to the BPA) as a company we are happy to use 4" shells at 75m but never any closer, you can see in your last clip fireworks can and do go wrong seeing them that close, knowing they were homebrew (not saying your shells are poor quality) and there were children around made me very nervous!

 

A 2" shell will punch a clean hole through 1/2" ply.............

Edited by Masterchief, 14 January 2013 - 06:42 PM.

[Sparky]

Hi Masterchief,

 

I'm not going to claim I had my audience 100 meters away but the garden is large and I suspect the camera being zoomed in for the whole thing made it look closer than it was. The garden is about 60 meters long and I was deliberately angling the shells at about 15 degrees over to wasteland behind. I was also only firing single shells, using paper mortars and shells so we wouldn't have the problem of tubes being blown over by a failure or by any dangerous debris from a failed mortar tube etc,

 

The kids were also back behind the camera. I think next time I will have them stand inside for the 4 inch shells though.

 

I really don't have anywhere larger to fire these.

[Vic]

Well done, you are well on your way

[Karl Mitchell-Shead]

With build quality like you have shown you sould'nt have to worry too much but it always pays to think 'worse case scenario'

 

Looking forward to seeing more!