[WIP] French Periscope View

[keltos01]

I decided to start a thread on the subject so as not to clog the Surcouf thread with technicallities, this view is intended for the Surcouf submarine.



Hautpoul over at Mille Sabords says :

document d'archive relatif aux sous-marins français provenant de l'Etablissement de Communication et de Production Audiovisuelle de la Défense.

notice the letters ECPA D on the image. It is from a French Defense News Archive.


Periscope's view analysis

view divised in 4 with crosshairs,

one vertical scale to the left at 9 divisions distance from the center one : how many degrees/grads ?

a parallel hair to the horizontal one at 9 graduations : how many degrees/grads ?

a scale close to the center vertical line with many smaller divisions : how many degrees/grads ?

still in the picture I was given there is a line of marks right of the central crosshair, that does not show on the german reticle, so maybe it's a french copy of the german design with their own needs added :

maybe I could start from the german periscope in SH4 then... isn't it ironic : french using german design ?



This following source are from french submarines (diesel/electric) but from the 70's

Periscope from a diesel electric french submarine from the 70s (Doris):
http://www.netmarine.net/bat/divers/...e/histoire.htm

Another periscope from a diesel electric french submarine from the 70s (Flore):


Periscope view of the La Flore submarine, La FLore museum

what I've done so far :


French Periscope v 1.3


lines and hatch marks were made from Hautpoul's still photograph through a french scope.


download v1.3 of the French Periscope Patch :

http://www.mediafire.com/file/xvh3pu...atch%20v1.3.7z

keltos

[Hitman]

one vertical scale to the left at 9 divisions distance from the center one : how many degrees/grads ?

a parallel hair to the horizontal one at 9 graduations : how many degrees/grads ?

a scale close to the center vertical line with many smaller divisions : how many degrees/grads ?

In most periscopes you will see (NOT in the US ones, BTW) the field of view has a vertical and an horizontal scale, where the vertical one is divided in milliradians (10 milliadians = Aprox 5.75 degrees) and the horizontal in degrees. Such is the case in the periscope view from Flore, as you can see that the vertical and horizontal divisions do NOT have the same size.

Now, in the typichal pictures from german WW2 films you can see, as well as in this one you have posted that is apparently from WW2 french defence ministry, the divisions are more peculiar. You can see that sometimes there are 5 and sometimes there are 4 divisions between the "10" mark and the central line of the crosshair. Why? We had a discussion long ago about that (Look HERE), but so far I think that the best explanation possible is that the reticle combines BOTH milliradians and degrees, i.e. where you have less divisions you are actually seeing degrees, and where you have more divisions you are seeing milliradians. This would allow to have both degrees and milliradians in both vertical and horizontal scales.

[keltos01]

Originally Posted by Hitman

In most periscopes you will see (NOT in the US ones, BTW) the field of view has a vertical and an horizontal scale, where the vertical one is divided in milliradians (10 milliadians = Aprox 5.75 degrees) and the horizontal in degrees. Such is the case in the periscope view from Flore, as you can see that the vertical and horizontal divisions do NOT have the same size.

Now, in the typichal pictures from german WW2 films you can see, as well as in this one you have posted that is apparently from WW2 french defence ministry, the divisions are more peculiar. You can see that sometimes there are 5 and sometimes there are 4 divisions between the "10" mark and the central line of the crosshair. Why? We had a discussion long ago about that (Look HERE), but so far I think that the best explanation possible is that the reticle combines BOTH milliradians and degrees, i.e. where you have less divisions you are actually seeing degrees, and where you have more divisions you are seeing milliradians. This would allow to have both degrees and milliradians in both vertical and horizontal scales.

french like it complicated

looks a lot like a german reticle don't you think ?

[Hitman]

looks a lot like a german reticle don't you think ?

I always thought so. Since France was under german domination and the Vichy government plainly colaborated, it would not be much amazing that they also had german propaganda films and such.

[makman94]

Originally Posted by Hitman

....You can see that sometimes there are 5 and sometimes there are 4 divisions between the "10" mark and the central line of the crosshair. Why?.....

hello Hitman and Keltos,

that is the 'strange' thing with the german scopes ...the space between the left '10' (at horizontal scale) is diveded to five equal spaces and on the other side the space between the right '10' is diveded to four equal spaces. another 'tricky' point is that the distance of left '10' to zero is NOT equal with the distance of right '10' to zero .
that means that the two '10's are not placed at the same degrees (none of it is representing degrees for obvious reason).

i have many reasons to believe that the left '10' is placed at 6.25 degrees (and not at 5.71 as it should for showing d=10xmast.but even at 6.25 the distance is very close to d=10xmast ) and the right '10' is placed at about 6 degrees .

i believe that the reason for this difference at '10's positions has to do with the difference at FOV that german scopes had between low and high power . if ,for example, at x1,5 the fov=38 then at x6 should have been fov=9,5 which is not happening .don't 'stick' with the fov's numbers at my example...i remember that there is a difference at fovs in high and low power at german scopes. so my thought is that the left side of scale where used at low power and the right side at high power.

same goes for vertical scale too...

[Hitman]

so my thought is that the left side of scale where used at low power and the right side at high power.

same goes for vertical scale too...

Hey, that's another very clever idea, that could very well explain the reason for the assymetrical reticle I'll dig a bit deeper into that, good job Makman

You know, there's nothing like a greek guy when it comes to studying and explaining geometry

[keltos01]

german scope :


http://www.ina.fr/histoire-et-confli...e-nord.fr.html


left of the vertical line :
number 10 placed after 5 divisions

right of the vertical line
number 10 placed after 4 divisions !

vertically to the left :
number ten placed 5 division above the horizontal divider

number ten placed 4 division under the horizontal divider !

french scope :


I wasn't sure about the horizontal line of marks above the horizontal dividing line

and I remade the marks spaced as should be ?





is it me or are the dividing marks not spaced evenly in the german scope ?