RE: [PSUBS-MAILIST] bubble pressure (Papenberger)

["Jens Laland" <laland@artematrix.org>]

David

"The so-called Papenberg depth gauge is used by the German Navy for
precision reading at periscope depth. Ref.:
http://lab.artematrix.org/submarine/images/project/papenberg_and_trim_principles.jpg
The measurement is based on the compression of an air cushion, and so the
reading in the cylindrical glass tube is not linear. The residual buoyancy
of the boat associated with its floating position is plotted on this
instrument in addition to the depth scale (starting with the surfaced
flotation line and decreasing to zero when the top of the superstructure
has been reached). Moreover, the contour of the cross section of the boat
is plotted in association with the depth scale (distorted). The water
level of the instrument is illuminated horizontally, and minute tendencies
for attitude changes can be identified from the curvature of the meniscus
before the water level in the tube rises or falls."
http://lab.artematrix.org/submarine/images/project/papenberg_trim_sketch.jpg
(from the book: 'Submarine Design' by Ulrich Gabler)

Here is a photo from inside an old norwegian (but german built) Kobben
class submarine, ref.:
http://lab.artematrix.org/submarine/images/project/IMG_0224.jpg

and here one from U 995 (type VII C) in Kiel (Laboe), ref:
http://lab.artematrix.org/submarine/images/project/IMG_0209.jpg

If you decide to make one then let me know as I have made a little program
that calculates the offsets needed to space out the scale correctly, i.e.
according to how you physically size your own gauge (ID of glass tubing,
length of scale, start air volume, etc). I also have a few sketches on how
to make the various parts, and how to assemble, plus some ideas on how to
test and calibrate the final thing when installed in your boat.

regards,
Jens







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