Ranging and fire control problem

[Jace11]

Great News

[jmr]

So the observation scope has a max zoom of 6x?

Snip from the Fleet Type Submarine Periscope Manual page 137.

"4. The stadimeter scale dials are graduated

for use with the periscope in high power.
When necessary to range on an object more
than 130 feet high, the stadimeter may be
used with the periscope in low power, and
the object set up on the height scale dial at
one-fourth its actual height. The range
reading is then correct."

The actual Stadimeter was installed with a "Course Angle Finder" as well as the Range Finder. What you did was, similar to the range finder, to adjust an image in length so it would fit with the actual image. Thus you could read out a Course Angle at the Stadimeter on the periscope....neet WE WANT THAT UBI

[Charos]

Originally Posted by jmr

So the observation scope has a max zoom of 6x?

From what I have read and understand both the Attack and Observation periscope are both 1.5X and 6X magnification in low and high range respectively.

You may ask then why both scopes?

Well the following comes to mind:

#1 Obs scope has less optics- In reality I dont think it is kitted with a stadimeter.

#2 Its a backup should the optics go in the main scope due to pressure via normal operations or depth charges.

#3 It has larger ojective lense and optics - just like a telescope it will gather more light and resolve smaller/fainter objects better IE: Stars and planes.

#4 It has a greater vertical range of movement.

#5 Downside is that for all its advantages the Obsevation scope is easier to spot when in use than the attack periscope.

[jmr]

Charos, by chance do you have Kim Ronof's Range Calculator Mark 3B whiz wheel handy? It was written in the SH 1 days and is capable of giving range in magnifications 1x, 2x, 4x, and 8x. Since the periscopes don't give us 2x, 4x, and 8x, we're limited to just 1x but even then I'm getting inconsistent results even with Krupp's ship dimension fix.

[Charos]

Originally Posted by jmr

Charos, by chance do you have Kim Ronof's Range Calculator Mark 3B whiz wheel handy? It was written in the SH 1 days and is capable of giving range in magnifications 1x, 2x, 4x, and 8x. Since the periscopes don't give us 2x, 4x, and 8x, we're limited to just 1x but even then I'm getting inconsistent results even with Krupp's ship dimension fix.

Jmr

I intend on doing some extensive range tests with Krupp's figures .
I dont have the Whiz wheel you speek of - I do all my Trig with an Electronic slide-rule (calculator).

Could you tell me what ship you were attacking. There may be some out there that still need mast height adjustments - dont forget Krupp's fixes were only for Japanese
shipping the allied stuff is not corrected as yet.

[jmr]

Ahhhhh only fixes for Japanese ships so I guess that explains why I wasn't getting the correct range on American ships.

I just used the sub school training missions and I was able to get accurate periscope/whiz wheel ranges on the Japanese ships. However, on the navigation training exercise two US vessels pass off the port side, a Victory cargo and a T3 tanker, neither of which I could get accurate ranged with the periscope and whiz wheel. On the torpedo and artillery training missions I had no trouble getting accurate ranges with the same tools on the Mogami cruiser and a medium modern composite (don't know the Japanese name for it).

Wish I knew how to change the periscope mag so that it matches one of the whiz wheel's mag so I could get accurate readings at long range. 1x just doesn't cut it for those far away ships.