After a week's assembly and testing, Roland and Anna finally completed developing the impact fuze for the bomb.
Compared to the fuze for the artillery shells, there was no need to withstand high temperature and pressure, nor high-G overload when during the detonation, that's why the structure was surprisingly simple. But even for such a simple thing which was made up of a firing pin and a spring, they had to conduct countless experiments to succeed.
The main issue was that no one knew how much elasticity the spring required to avoid ignition during an accidental fall. In the same time, they had to guarantee the firing pin would trigger the bomb during a normal launch.
He and Anna could only test this by changing the thickness and the hardness of the spring little by little.