In 1917-18 University College London (UCL) carried out a range of detailed scientific experiments on the burning rates of pyrotechnic fuzes, varying the chemical composition of the time fuze mixture, test pressure and spin rate. The work was done in parallel with predictor experimentation in order to develop an accurate anti-aircraft capability.
Sulphur percentages of 0%, 5%, 10%, 15% and 20% in the black powder mix were used, the saltpetre concentration being kept at 75%; atmospheric pressure and half atmospheric pressure were selected; and spin rates of 0 (i.e. stationary), 10,000, 15,000, 20,000 and 25,000 rpm were tested.
One key finding of the report was:
"There is no great difference in the effect on time of burning produced by spin in the case of powder varying in sulphur content from 0% to 10%. With 15% sulphur this effect is considerable, while powders with 20% sulphur are useless for spins greater than 10,000 rpm."
Back in the 1880-1910 time frame, it is probable that the sulphur content used in the fuze pyrotechnic trains was such as to create slower burn times - depending on the propellant charges used and shell weights (and thereby spin rates) - compared to stationary burn. The science of this only became fully understood in the latter half of the Great War, but it was accommodated at the time of the Boer War by perhaps producing the necessary amended range charts.
Tom.
Sulphur percentages of 0%, 5%, 10%, 15% and 20% in the black powder mix were used, the saltpetre concentration being kept at 75%; atmospheric pressure and half atmospheric pressure were selected; and spin rates of 0 (i.e. stationary), 10,000, 15,000, 20,000 and 25,000 rpm were tested.
One key finding of the report was:
"There is no great difference in the effect on time of burning produced by spin in the case of powder varying in sulphur content from 0% to 10%. With 15% sulphur this effect is considerable, while powders with 20% sulphur are useless for spins greater than 10,000 rpm."
Back in the 1880-1910 time frame, it is probable that the sulphur content used in the fuze pyrotechnic trains was such as to create slower burn times - depending on the propellant charges used and shell weights (and thereby spin rates) - compared to stationary burn. The science of this only became fully understood in the latter half of the Great War, but it was accommodated at the time of the Boer War by perhaps producing the necessary amended range charts.
Tom.