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
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
to Sextants other