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-   -   Mast Height divded by Sine Alpha (https://www.subsim.com/radioroom/showthread.php?t=182441)

LCDRStrungShadow 04-10-11 09:43 PM

Mast Height divded by Sine Alpha
 
:timeout: I attempted to determine range using this equation:

Range = Mast / Sine Alpha


Range = (25) / sine (.6)

Range = 34.85...

But the stadimeter tells me otherwise: 2,700 meters.

Am I missing something?

Gargamel 04-10-11 09:50 PM

Error of the seas.

The scope/ UZO/You is not at sea level, and that is oscillating with the waves. The target ship is too oscillating on the seas.

I'm a little rusty on my trig to know if the calcs are right though.... let me check...

What are the numbers? 25 is mat height, but what's the .6? From the unit circle?

Also, wouldn't range = mast / tan ø work? But as I said, my trig is 18 some years rusty, so feel free to educate me.

Pisces 04-11-11 06:20 AM

I think he made a typo, since 25/sin(0.8)= 34.85, but that is ONLY if your scientific calculator is set to using radians as a unit of angles (0.8 radians= 45.8 degrees!)

So what did you use to measure the angle to be 0.6 (or 0.8)? I can't explain the 2700 meter range thus far.

Oh, and mathematically correct would be the tangent function, but the difference is neglectable unless the distance is quite close/angle-size is great.

benitorios 04-11-11 03:49 PM

As Pisces pointed out, there seems to be a unit problem. The 0.8 degrees need to be converted into radians, if that's how your calculator is set up. Also, using tan is probably more appropriate although the error is minimal indeed.

The correct formula would be: distance = 25 / tan (0.8*pi/180), where pi is 3.14159 (dont have the symbol on my keyboard)

The result is 1790 meters.

Could it then be that the 1.5x zoom level plays a trick on us here and that the stadimeter is not giving the right angle, but the correct distance after zoom correction? Ie.1790 * 1.5 = 2685 meters.

I would say the zoom level you use shouldn't affect observed angle, but perhaps the game doesn't account for that, gives you an off angle, but fixes its own error by giving the correct distance in the end?

Or is it me, conveniently thinking to multiply by 1.5 as it fixes the above? :O:

Gargamel 04-11-11 04:16 PM

So, as I'm senile.... radians -> degrees is Radians * pi / 180?

Pisces 04-11-11 05:46 PM

Quote:

Originally Posted by benitorios (Post 1640692)
Or is it me, conveniently thinking to multiply by 1.5 as it fixes the above? :O:

It all depends on what the OP is using as GUI/Periscope mod. Until that is cleared up and how he got the angle value there's little point in guessing ranges.

Pisces 04-11-11 05:47 PM

Quote:

Originally Posted by Gargamel (Post 1640718)
So, as I'm senile.... radians -> degrees is Radians * 180/pi?

{Silently flips pi/180 around while Gargamel isn't watching not to make him feel embarrassed.} ;)

LCDRStrungShadow 04-11-11 07:45 PM

Huh?
 
Ok I got the mast height from the classification notebook...

I got the angle in degrees from the UZO using the tickmarks, each small tickmarks was .2 degrees; and my target counted 3 so I got .6 degrees.

Mouftic 04-11-11 07:55 PM

yeah! What he said...:-?

This is Chinese to me.... and I don't speak it.:dead:

That's why I have officers to help me.:arrgh!:

Gargamel 04-11-11 08:07 PM

The next question is... what is mast height? Is that from keel, waterline? deck? I would assume waterline......

Sledgehammer427 04-12-11 12:06 AM

I remember accurately reading the distance between me and the bricks on the other wall in the room using my calculator and two pencils.

god forbid I remember what I did, it was only a year ago.

but I used the two pencils, one at eye level, the other angled up, I would use the points to measure a rough amount of degrees, then I would input that into my calculator (with sin function) after measuring the approximate height of the bricks.

from that, I would get a range estimate in feet accurate to withing a couple inches.

I know that may have NO BEARING on this at all, but its kind of a fun project to do when you are bored....now if only I can remember my calculations.

TorpX 04-12-11 01:14 AM

range = mast height / tangent a

You will need to use calculator in degree mode as I doubt kriegsmarine used radians in their periscopes. :DL

postalbyke 04-15-11 08:38 PM

i use a slightly modified magui mod, but you can try OLC gold also :D the zielkerswinkel is a circular slide rule set up to make those measurements corrected for magnification.

to correct for any "in-game" effects, i would take measurements with the "manual input" for fire control turned off so you have a meter-by-meter baseline, then redo your math corrected for in-game environment...

makman94 04-16-11 04:52 AM

Quote:

Originally Posted by LCDRStrungShadow (Post 1640846)
Ok I got the mast height from the classification notebook...

I got the angle in degrees from the UZO using the tickmarks, each small tickmarks was .2 degrees; and my target counted 3 so I got .6 degrees.

first don't rely on rec manual mast height values as most of them are not correct

second: the ''.2 degrees'' that you say for uzo's marks is NOT correct . to find out what degrees each mark at uzo shows depends from the settigs at uzo's camera values .in there ,at zoom's value the stock value is 7 which means that each mark that you see at uzo is 1/7=0,1428 degrees

edit : third : as,allready,the above subsimers told you the correct formula for getting range is range=mast/tan(θ) [forget that ...'sin' there]

Quote:

Originally Posted by benitorios (Post 1640692)
.....

Could it then be that the 1.5x zoom level plays a trick on us here and that the stadimeter is not giving the right angle, but the correct distance after zoom correction? Ie.1790 * 1.5 = 2685 meters.

I would say the zoom level you use shouldn't affect observed angle, but perhaps the game doesn't account for that, gives you an off angle, but fixes its own error by giving the correct distance in the end?

Or is it me, conveniently thinking to multiply by 1.5 as it fixes the above? :O:

the game is adjusting the degrees scale at low power (whatever this low power is ) so the stadimeter is ALWAYS showing the correct distance . this is not affected by anything (whatever settings you may do at scopes) ,the game will render the CORRECT degrees scale at low power and stadi will always work perfect and shows the correct distance (this is hardcoded and thank god for that becuase devs made a perfect job at this specific part)


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