this page describes
Speed simulates the motion of a bell by integrating the governing equations of motion.
The clapper is assumed frictionless and to make an inelastic collision; one may allow for friction in the motion of the bell. None of these assumptions will bear significantly on the determination of whether a particular clapper suits a particular bell unless the movement is very seriously impaired.
The integration is very accurate indeed; the time for a 'seconds' bell, ie one having a period 2 seconds for small oscillations, to swing through an angle of 350 degrees is calculated at 2.877 647 seconds against an exact value of 2.877 664 seconds, so there are no worries about stability problems with the numerical method.
The user has to supply the necessary mechanical parameters of the system, one of which, at least, is not easily determined for tower bells, namely, the distance from the axis of rotation of the mass centre of the bell. Presumably one would need to measure the rotation induced by a given load on the rope, allowing that one knew the mass of the bell accurately.
The parameters of a particular system may be saved to file and recovered. These files are simple NotePad documents, and so may be edited offline.
There is a graphic real-time representation of the motion. This is reasonably smooth; the problem here is that Windows will not send sufficiently accurate time interrupts; it may take time off for reasons of its own. The program reports the angle of the bell at impact and the force of the blow. It may be paused, as indeed it was for the purpose of obtaining the above graphic.
The material to be downloaded is in zip format. Click on the icon to initiate unzipping. You will be asked where to place the unzipped material; most simply, prepare a folder
for this purpose. There is a single folder speed, and a ReadMe text file. Click here to download Speed.The suggested BRF donation is £5.