Tachymetre, Start/stop – Chase-Durer Fighter Command User Manual

Page 12

10.

Tachymetre

slower, such as a bicycle, you must use a shorter
distance because the elapsed time must fall within
the

second range.

For this example, it took 36 seconds for a cyclist
to travel 1/4 of a mile. Reading the TACHYMETRE
dial displays a speed of 100mph, but the cyclist only
traveled 1/4 of a mile, so the actual speed would be
1/4 of that or an average speed of 25mph over the
quarter mile.

Example No. 2 – To measuring something much

7.2 - 60

Using the TACHYMETRE scale
The TACHYMETRE dial is mainly used to compute an average speed after noting how long it takes to travel a
fixed distance (like one mile or one kilometer), but it can also be used to compute many other things.
The dial is a logarithmic scale that uses this formula to compute:

The chronograph second hand indicates 1/10, 1/4, 1/2, 1, 10, 100 or 1,000 etc. units (miles, objects, pounds
etc.). When stopped, the second hand points to the number on the TACHYMETRE scale by which the number
of units (1, 10, 100 or 1,000 etc.) must be multiplied to obtain per-hour production rate or per-hour speed.

TACHYMETRE DIAL = 3600 / Elapsed

Time In Seconds

seconds. The second hand, stopped as the mile
marker is passed, reads 120 on the TACHYMETRE
scale. Average speed of the car is 120 x 1, or 120
miles per hour.

Although decimal units (100 liters, 1 mile, 10
kilometers) make computing simple, in practice, the
TACHYMETRE scale can be used to calculate
velocities and production rates from any number of
units.

Example No. 1 – A car covers one mile in 30

START/STOP

CHASE-DURER

FIGHTER

COMMAND

ALARM

DATE

1/100 SEC

330 FEET

GENEVE