16 replies to this topic

[knackers]

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).

thats an excellent table to have at hand fred, my hemis are 67mm

[Green_as_my_powder]

Thanks to all for the info!