British General Purpose Bomb measuring instrument ?

[Mossie]

Dear gents,

I hope anyone can tell me the exact purpose of this measuring instrument. It is 7.2 inches long and 0.5 inches width. The one side is for G.P. 250 LB. Height feet x 1000 (3 to 20) and terminal velocity = 1.410. The other side is for G.P. 120 LB. Height feet x 1000 and also from 3 to 20 and terminal velocity = 1.240. It has a Mk. IX A or C. Perhaps a maker mark A.K. 31 and a inspectors stamp 'NW 38' in a circle. It is made from aluminium and black painted with white markings.

Please see the pictures.

Thank you,
Rgds,
Mossie

 

[butterfly]

This is a scale used on the Mk IX course setting bomb sight. There were different scales for the different bombs as they all had different TV (terminal velocity). This clipped to the upright post of the sight.

regards Kev

 

[Mossie]

Hi Kev,

many thanks for your answer. I have found a good photograph of the CSBS on the net and the so called "height bar" well visible.

Rgds,
Mossie