BRADY RULES ©

Arc Construction
Arcs of various radii may be drawn by placing a pin in the zero hole of the scale and a pen or pencil in the hole near the desired radius of arc.

Compass Rose
The rose may be north aligned or track aligned.

North Aligned
Read track clockwise on the inner scale. To assist, the numbers are also north aligned.

Track Aligned
This is the preferred method for measuring short tracks, using the outer scale.
Place the centre of the aircraft symbol on a meridian close to the track.
Rotate the compass until the aircraft is pointing parallel to track in the correct direction. Read track anticlockwise on the outer scale.

Roamers
The large roamer is 1: 25,000 or 1: 250,000. The smaller roamers are for 1:50,000 charts.


Speed Scales and Turning circles

Mk-1
Minutes are marked at 1: 250,000 scale.
Dots indicate 10-second intervals on a 1: 50, 000 run.

MK-3, Mk-4
Minutes are marked at 1: 500,000 scale.
Triangles indicate 10-second intervals on a 1: 50, 000 run.
Radii equate to 2g, 3g or 4g turns at the appropriate speeds.
The semi-circles are for fixed rate turns at 1.9º per second.

Notes
The Rules are made of a specially selected non-crazing plastic. It is NOT indestructible, but will survive shallow bending in aircrew pocket books. Please do not write on the underside of the rule or clean it with spirit. The black marks will come off. If you want to write on it, use a permanent OHP pen on the top surface and clean it carefully.

Brady Rules have been in popular use with RAF fast jet crew since 1987.