View Single Post
Old 03-18-2010, 07:05 PM
mousegun mousegun is offline
Join Date: Oct 2009
Location: the oc
Posts: 776

Originally Posted by edlmann View Post
Back before the development of the modern chronograph, I believe velocity was tested by firing a projectile at a swinging pendulum of a known weight at a known distance. High speed photography would measure how far the pendulum was moved and the velocity computed from that.

Prior to Oehler's chronograph, a lot of inaccurate velocity estimates were in print.
The ballistic pendulum went out of serious use at armories over a hundred years ago. Instrumental velocities in the time of John Garand were quite accurate and reliable if not tedious to measure. According to Hatcher's Notebook on page 251 service ammunition was measured with a Le Boulongé chronograph. The setup and method of measuring instrumental velocities with the chronograph is described on page 404.

A typical chronometric measurement around the turn of the century was probably made with an electromechanical apparatus consisting of frangible detector screens, a source of high voltage and a recording device. The recording device was usually a hysteresis/synchronous motor driving a waxed disk with a conductive backing on a spindle. A worm grear drove a stylus in a spiral track on the disk. High voltage (90-200V) was connected across the fragible screens and the leads connected to the stylus through a "kicking" inductor. As the bullet passed through the screens the short caused a high voltage spike on the stylus to arc through the disk. The angular distance on the disk between two arc spots indicated time of flight. Very accurate...

..and expensive.
----0000--(. .)--0000----

Last edited by mousegun; 03-18-2010 at 07:15 PM.
Reply With Quote