UZO range estimating to target

[NiceSub]

Originally Posted by derstosstrupp

Not sure these factors are correct. You need to multiply by the sine of the observed angle on bow, which should be a decimal place.

So 220 m target at a 90 AOB using the numbers above would be 2000 m away, if it were at 60 AOB taking up the same length in the UZO it would be closer (2000 x sin(60) = 1732).

Unless you mean divide, in which case:
AOB 60 —-> 1.15
AOB 45 —-> 1.41
AOB 30 —> 2

Right so based on your knowledge how can I use UZO to estimate range by counting tickmarks or something else?

[derstosstrupp]

Originally Posted by NiceSub

Right so based on your knowledge how can I use UZO to estimate range by counting tickmarks or something else?

I personally haven’t tested the tickmarks, but to the extent someone figures it out, the AOB rules can be used. If you do want to use the ticks, I’d say make use of the mission editor and set up a ship at a known distance, your boat stopped. Then measure with the UZO based on length to figure out the calibration.

During the day, if I need range on the surface because I want to plot, I’ll move so the target’s mast tips are just showing and eyeball the range with the binos. A ship with mast tips showing is about 15-16 km away. This is enough to get course/speed of the target over time. Every 5 minutes, note whether it came closer or got further away, and change course to keep the masts the same size. Makes plotting this way easy.

As for ranging at night with the UZO, here is where knowing the tick calibration would help. There was only a vertical line in the historical UZO, no ticks, but what they would do is estimate range by how much a target of x length filled the optics. Not exact by any means, but more than enough, since the shot was made with a low gyro angle anyway, making range irrelevant. So either finding the calibration of the ticks, or knowledge of the in-game FOV would allow you to do the same.

I’m curious now, might take that as a to-do....

[Storm501]

@derstosstrupp


You are right, the range should be divided with those factors if the ship is not AOB90, as it fills less of the FOV compared to AOB90.

[Storm501]

@NiceSub



Two ways to determine range. First based on formula here for the more realistic periscopes mod. https://www.subsim.com/radioroom/sho...d.php?t=165408

1) Mast height 33,5m x 4000 / (14 ticks x 10 mil/tick) = 957m range

Second method which I mentioned earlier, about filling the UZO/PER with target length.
2) Target lenght is 137,7m. We work with the table below...

Ship  /    length /  UZO /      6x /    1,5x 
LINER /    220 /    2000 /    1800 /    500   
LMER /    180 /    1600 /            1500 /    450
TANK /    160 /    1500 /            1200 /    400
MMER /    100 /    900 /            800 /    200
SMER /    75 /    700 /           600 /    120
BOAT /    25 /    200 /      160 /    40

If the ship aspect is outside AOB90, divide the above by this.

AOB    60    1,13x        
/////    45    1,42x        
  /////    30    2x

So 137,7m is between TANK160/1500m and MMER100/900m. A bit on the larger side. So we can interpolate that the range is 1270m. If we can agree that the ship is AOB110 (same effect as AOB70), we can divide the range with a factor of 1,1. So we get 1155m considering the AOB effect on apparent length of the ship.

Final results:
1) 957m
2) 1155m

Neither method will never be completely accurate, the target is roughly at 1000m range.

The tick method becomes really difficult around 1000m range as target fills the UZO and it is difficult to count all the ticks above 10. So that is why the faster FOV method becomes really useful at close ranges.

[Markus Witt]

Seems that the graticules on the UZO should be used the same way as both periscopes at 6x zoom. I did a little test to confirm. While in port I took the range of a freighter berthed alongside the quay. I used the 6x zoom for both periscopes and counted 12 centirads (120 milirads) on both scopes. With the UZO I also counted 12 marks. Vessel was a N-type freighter with a mastheight of 28 meters. See attached.

Normal zoom is 1.5x, so when zoomed in the marks counted must be divided by 4 (6 / 1.5 = 4) to get the correct number of centirads. So in this example the actual angular height is 12 / 4 = 3 centirads. That gives a range of (28 / 3) * 100 = 933 meters. To confirm the range I fired a torpedo at the freighter, a steam torpedo at slow speed (30 knots) which hit after 61 seconds. Based on torpedo running time the range was 30 * (1852/3600) * 61 = 941 meters.

So to find the range with the UZO count the actual marks (ignore the number 10 next to the scale, this is meaningless) and divide by 4 to get the correct centirads. Range in meters = (mastheight / centirads) * 100.
Or calculate as (mastheight / markings) * 400.