Fred

Takeo Shimizu discusses the size of the gap between shell and mortar in his book „Fireworks from a Physical Standpoint“, first edition 1976 in german language „Feuerwerk vom physikalischen Standpunkt aus“: Chapter 12 „Die Ballistik der Feuerwerksbombe“ (12.3 Aussenballistik, part 5 at page 186).

Shimizu gives a formula:
If „(diameter of shell * diameter of shell) / (diameter of mortar * diameter of mortar) ≤0,5“, the gap size is too much.


Shimizu used to shoot shells with ratio between 0,83 und 0,90 (page 188 table 35).

See a table for different sizes at http://www.pyrobin.com/files/engl.jpg

Is there an ideal tube i.d. for, say a 2 1/2" o.d. shell? The club that I'm with has 3" launching tubes, what is the best final o.d. of a shell for this size tube?

Takeo Shimizu discusses the size of the gap between shell and mortar in his book „Fireworks from a Physical Standpoint“, first edition 1976 in german language „Feuerwerk vom physikalischen Standpunkt aus“: Chapter 12 „Die Ballistik der Feuerwerksbombe“ (12.3 Aussenballistik, part 5 at page 186).

Shimizu gives a formula:
If „diameter of shell²/diameter of mortar² ≤0,5“, the gap size is too much.

Table:


Shimizu used to shoot shells with ratio between 0,83 und 0,90 (page 188 table 35).

A tutorial how to cast your own lead media
(in german, but several pictures):
http://1click.pyrosz...geltutorial.pdf

Hi Jerronimo

Sounds interesting Fred, how did you discover this compound?

Mowital known and used as a very good binder among german speaking hobby pyrotechnicians.

is it used in mass production?

I dont know whether the pyrotechnic industry uses it.
Or did you ask about other use in industry? Yes, it is. Google for
„Mowital 30B“ or visit www.kuraray-kse.com.

any small quantity source of the stuff?

Yes. For UK, you can buy it at
AP Fitzpatrick Fine Art Materials
142 Cambridge Heath Road, London E1 5QJ
Tel 0044 207 790 0884
http://www.apfitzpat...er_pigments.pdf
100g £ 2.60

Edit: I did not see that you are from the netherlands.
Ask
G de Ru, Verf-Glas-Behang-Autolakken
Van Woustraat 145, 1074 AJ Amsterdam - Z.
Phone 0031 206760631

Test it, you will be satisfied:
High soluble, easy to work with, not expensive - a perfect binder.

Has anyone ever successfully made cut D1 glitter?
Cut stars need a high percentage of water typically 15+ % and I'm afraid this will ruin the delay effect of the bicarb.?

(excuse my english, it´s not my language)
To avoid the D1 beeing decomposed by too much water use Mowital B (=Polyvinyl butyral) as binder.
„Mowital B“ is produced by www.kuraray-kse.com.
Polyvinyl butyral is highly soluble in alcohol and 3% will be enough to bind D1 cut stars successfully.
Polyvinyl butyral doesn´t have any bad influence on the glitter effect.

With Mowital you can easily make D1 cut stars without boric acid.
Add 3% Mowital to the priming composition and use alcohol for priming, too.
D1 don´t need much prime.