Extra Kollsman Altimeter Pointers

[[email protected]]

I have an old Square D Kollsman 3 pointer altimeter that I think it's
about 50 or more years old and seems to be in working condition. The
body is about 2 13/16 diameter. The label on the back says part no.
371K-05

The three altitude pointers give the usual altitude readout. The little
Kollsman barometer window works and I know how to synchronize a known
altitude with the known barometer pressure by removing the little screw
and pulling the Kollsman knob out for the 'calibration'.

Now here's my question. There are two extra little visible pointers on
this altimeter that both rotate around concentric circles centered on
the instrument face. What are these pointers for. One is on the outer
circumference of the dial and the other one is on a smaller inner
circle with a radius of about 1 inch. Both pointers rotate when the
Kollsman knob is turned. They do NOT respond to air pressure changes.
The outer one moves at the same rate as the hundreds altimeter pointer
when the knob is turned. The inner pointer increments 100 feet when the
outer pointer makes one complete revolution around the face.

What are these "extra" pointers for???? They seem to serve no other
purpose than measuring the rotation of the Kollsman knob.

Dennis

[Jose]

> What are these "extra" pointers for????

What do they indicate at 29.92? How fast do they move (if you take them
to indicate an altitude?)

Jose
--
You may not get what you pay for, but you sure as hell pay for what you get.
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[[email protected]]

What do they indicate at 29.92? How fast do they move (if you take
them
to indicate an altitude?)

If I set the Kollsman to 29.92, the little pointers indicate 1,740 ft.

They only move when I turn the Kollsman knob and the pointers turn in
sync at the same rate as the hundreds and thousands regular pointer
hands move. The pointers do NOT move with actual air pressure changes,
only when I manually rotate the Kollsman knob.

[Mitty]

Are they showing pressure altitude? Are the main pointers showing 1,740 at
29.92, too?

On 7/3/2005 12:18 PM, wrote the following:
> What do they indicate at 29.92? How fast do they move (if you take
> them
> to indicate an altitude?)
>
> If I set the Kollsman to 29.92, the little pointers indicate 1,740 ft.
>
> They only move when I turn the Kollsman knob and the pointers turn in
> sync at the same rate as the hundreds and thousands regular pointer
> hands move. The pointers do NOT move with actual air pressure changes,
> only when I manually rotate the Kollsman knob.
>

[snj-5]

I have one of those in my airplane, but only (1) extra pointer
on the circumference. I recently had the unit overhauled and
the avionics shop guy said he was told it was a Navy thing, and
the little pointer was an aid in determining just how far off
of 29.92 (in feet) one was when the local barometric pressure
was set.

I just ignore the feature....

Bela P. Havasreti

wrote:
> I have an old Square D Kollsman 3 pointer altimeter that I think it's
> about 50 or more years old and seems to be in working condition. The
> body is about 2 13/16 diameter. The label on the back says part no.
> 371K-05
>
> The three altitude pointers give the usual altitude readout. The little
> Kollsman barometer window works and I know how to synchronize a known
> altitude with the known barometer pressure by removing the little screw
> and pulling the Kollsman knob out for the 'calibration'.
>
> Now here's my question. There are two extra little visible pointers on
> this altimeter that both rotate around concentric circles centered on
> the instrument face. What are these pointers for. One is on the outer
> circumference of the dial and the other one is on a smaller inner
> circle with a radius of about 1 inch. Both pointers rotate when the
> Kollsman knob is turned. They do NOT respond to air pressure changes.
> The outer one moves at the same rate as the hundreds altimeter pointer
> when the knob is turned. The inner pointer increments 100 feet when the
> outer pointer makes one complete revolution around the face.
>
> What are these "extra" pointers for???? They seem to serve no other
> purpose than measuring the rotation of the Kollsman knob.
>
> Dennis

[[email protected]]

Mitty,

When I set the Kollsman window to 29.92 today, the main pointers show
about -200 feet (which is correct as the barometer now is actually
30.15). And as I mentioned, at a Kollsman setting of 29.92, these
extra pointers show 1,740 feet regardless of the actual barometric
pressure.

[Ron Parsons]

In article . com>,
wrote:

>Mitty,
>
>When I set the Kollsman window to 29.92 today, the main pointers show
>about -200 feet (which is correct as the barometer now is actually
>30.15). And as I mentioned, at a Kollsman setting of 29.92, these
>extra pointers show 1,740 feet regardless of the actual barometric
>pressure.

If these pointers are set to field pressure at your airport, then your
altimeter will read QFE. Your 30.15 was showing you QNH and set to
29.92, you read QNE.

If QFE is an unfamiliar term, it reads altitude above Field Elevation.
QNH is Nautical Height, and QNE is Nautical Elevation.