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Weapons depression Settings ??


IvanK

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Just had a look through the Depression tables published, The huge depression values looked way over the top to me so went to calculate some.

I took the example given in the IFE Manual for 45 deg Dive MK82 Slick, 5000' release Alt , 400KTas .. it calls for depression of 850mills !!

(The sight allows up to 999mills to be selected .....a crazy amount imo !)

Macchi-depp.jpg

So Took the worked example in the MB339A Weapons manual (which includes wind corrections) and re worked it to the same values in the India foxtrot Echo manual. The red numbers mine.  The ballistic figures for the MK82 taken from standard ballistic tables, the remainder from the 339A Weapons manual. The resultant Nil wind depression is just 140mills

Mb339-TACmanui-Calc2.jpg

So something is not right in the depression settings provided in the manual. By inspection they all look way to excessive to me. The Level release at 500' has the same depression as 45 Deg release at 5000' ??

 


Edited by IvanK
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Trying to resolve this (to me) huge disparity in depression settings real world calculation to quoted value in game documentation; I went into FMB and tested some calculations I made for level bombing using my settings. The result weapon impacts nowhere near the the pipper. So checked actual bomb range achieved (used a runway to get accurate length).. bomb range was very very close to the book numbers so ballistics are good.

So what is the issue ? I wondered if there was something wrong with the Mill values used in the depression setting and or an issue with the mill dimension of the reticle. Using the references in the manual conducted a test to see what gives.

Sitting on the Runway with Zero depression (Left image) the Top of the pipper is tangential to the red Runway lights. I then wound in the depression to set the top of the vertical bar to be tangential to the red runway lights (right image). This required in a game a depression setting of 70mills.

Mb339-mills.jpg

I then went to the reticle dimension diagram in the manual to measure the same angular value in the sight the answer was 9 mills ! .... a difference of 61mills. So either the depression relationship in the FIE MB339 is in error or the reticle sizes are in error. More testing to come to try and figure out whats what ... I suspect its the depression value scaling.

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And if we use the Mills diagram we can see that only about 100mills worth of depression should be usable.... which then begs the question is the Zero mill datum correct or the sight reticle size in mills correct ?

MB339-maxmills.jpg

Next checking Reticle Mills versus Known object size. Placed an IL76 with wingspan of 50.5m a distance of 1000m away from MB339. So Reticle should subtend wingspan. Results below.

IL76Akri.jpg

What you see in the sight .. something does not look right here.

IL76mills.jpg

My head now officially hurts 🙂 so off to fly and enjoy the wonderful thing the MB339 is .


Edited by IvanK
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So in dealing with the displayed reticle size. I took the IL76 image and the  Reticle sizes stated in the MB339 manual. Then using the image worked out what 50mills in Pixels should subtend (between the Yellow arrows) that came to 276pixels.  I then compared the FIE representation of 50 mills (White arrows) that came to 426 pixels.

IL76mills4.jpg

I conclude that he IFE MB339 Reticle is 1.54 times to big.

The second error is that the Mills depression scaling is also wrong. This is a little harder to determine but I think its in the order of 6 times to big. i.e. a supposed current entry of 850 mills should more reasonably be 140mills to provide a realistic real world sight line.

Tied in with all of this is the exact Zero Sight Line position in the combining glass AND its relationship to the 3D model  and the flight model AOA to IAS relationship.

A complex problem, but at present these errors prevent accurate/realistic weapons delivery calculation and or sight setting.


Edited by IvanK
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  • 3 months later...
2022/12/24 AM7点28分,IvanK说:

So in dealing with the displayed reticle size. I took the IL76 image and the  Reticle sizes stated in the MB339 manual. Then using the image worked out what 50mills in Pixels should subtend (between the Yellow arrows) that came to 276pixels.  I then compared the FIE representation of 50 mills (White arrows) that came to 426 pixels.

IL76mills4.jpg

I conclude that he IFE MB339 Reticle is 1.54 times to big.

The second error is that the Mills depression scaling is also wrong. This is a little harder to determine but I think its in the order of 6 times to big. i.e. a supposed current entry of 850 mills should more reasonably be 140mills to provide a realistic real world sight line.

Tied in with all of this is the exact Zero Sight Line position in the combining glass AND its relationship to the 3D model  and the flight model AOA to IAS relationship.

A complex problem, but at present these errors prevent accurate/realistic weapons delivery calculation and or sight setting.

 

I checked with a 14m long Su-25T from 185m away. It should be about 75.5 mil or around 1.5 times of the sight length, and it is with C-101 sight of same size, but it fills the exact length in MB-339. Correspond with your result.

However, it seems that most of us don't think it's a serious problem.😟

Human allowed, demon allowed, Deka never allowed.

Distort allowed, provoke allowed, fight back never allowed.

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  • 2 weeks later...
  • 1 month later...
On 4/21/2023 at 1:58 AM, Lookiss said:

What works for me is 800 mils, 45 deg dive, 2000-3000ft release. I tried doing the same at 140-150 and even 200,  but I was unable to get the same results.

No idea if it's real-world accurate, but it does work for me.

800 mills in a 45 deg dive is nowhere near Real world .... for any aeroplane !!!

A worked example in the 339 Weapons delivery manual for a MK82 40 deg Dive 3000' release at 300kts provides a total depression of 183mills


Edited by IvanK
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18 hours ago, IvanK said:

800 mills in a 45 deg dive is nowhere near Real world .... for any aeroplane !!!

A worked example in the 339 Weapons delivery manual for a MK82 40 deg Dive 3000' release at 300kts provides a total depression of 183mills

 

Good to know, thanks.  So something is off then :-)

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On 4/9/2023 at 4:57 AM, Torbernite said:

However, it seems that most of us don't think it's a serious problem.😟

I didn't say anything because I don't have the real world -34 and I didn't have anything to add to what IvanK already wrote, but I do care and I'd like to see this and other bugs (chiefly, the randomly occurring damage/explosion during taxi, due to inexplicable accelerations on the airframe). And, by now, I do think this module has been put aside by the devs: and I do hope they'll prove me wrong, very soon hopefully.

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  • 1 year later...
Am 19.12.2022 um 03:20 schrieb IvanK:

Just had a look through the Depression tables published, The huge depression values looked way over the top to me so went to calculate some.

I took the example given in the IFE Manual for 45 deg Dive MK82 Slick, 5000' release Alt , 400KTas .. it calls for depression of 850mills !!

(The sight allows up to 999mills to be selected .....a crazy amount imo !)

Macchi-depp.jpg

So Took the worked example in the MB339A Weapons manual (which includes wind corrections) and re worked it to the same values in the India foxtrot Echo manual. The red numbers mine.  The ballistic figures for the MK82 taken from standard ballistic tables, the remainder from the 339A Weapons manual. The resultant Nil wind depression is just 140mills

Mb339-TACmanui-Calc2.jpg

So something is not right in the depression settings provided in the manual. By inspection they all look way to excessive to me. The Level release at 500' has the same depression as 45 Deg release at 5000' ??

 

 

Hi, thanks for this valid report. Do you know where I can find the 339A Weapons manual?

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I don't have the module, but the order of magnitude of these depression values is completely unreasonable.

FYI 850 milliradians is almost 50 degrees. This depression setting would be well outside the HUD, somewhere inside the stick. Hard to imagine any sight would be able to display more than 200 mills. 

Maybe the sight scale has hidden decimals, so 999=99.9 mils? 

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You're right regard max mils :

collimatore aeritalia-saab rgs2.png

 

And no, there are no decimals (this is not a Hensoldt ZF 6-24x56).

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