Kollsman Sextants

The American firm Kollsman have produced several fine sextants and were possibly the last firm to cease production of them. Many will be found with name plates suggesting they were produced in Germany or the UK. They may have been assembled in those countries but they were made from American parts.

Their Periscopic sextants are very nice, clean and bright looking. They look the part. Perhaps more so than their European rivals. Compare the Kollsman with the RAF Mk I and 2 periscopic to see what I am trying to say.

Because the periscopic sextant is designed to remove the Astro Dome from a pressurised aircraft they have to be inserted into a rather elaborate skin fitting on the airframe. This skin fitting or Mount as they are called have to seal the air in when the sextant is removed and must have some form of heating to stop water freezing in them.

A view into the mounting.


because of the extreme cold and exceptional chill factor with the tip of the periscope sticking outside the aircraft's skin, powerful heaters are fitted to a periscopic sextant to stop any moisture freezing or obscuring the lenses.

The above illustrations show the complete instrument. On the left, just in front of the large Index knob can be seen the Index angle indication window and above it the averager window.

Kollsman produced a hand held version of this fine sextant It is essentially a periscopic instrument with the Periscope sawn off! It works just as well of course but is very bulky and heavy for its size. Because the sextant is designed to be used in a mount weight was not a design consideration so the hand held version is several times the weight of the Mk IX.

Both types of sextant were produced as bubble or pendulum versions and Kollsman even produced in the 70's, an electronic averager. It mimics the mechanical device exactly and does produce an easier method to read an average result clearly and quickly.

I thought my Birthday and Christmas had both arrived together when I opened my mail recently. A friend in Canada, Paul-Ernest, had generousley sent me a virtually brand new Digital Averager which you see above. Thanks PE!


Here is a shot of an Ex Nimrod Kollsman in its transit case.

The torch is the battery box for the Bubble or Pendulum illumination and has a BNC plug where the lense should be.


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