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Well I know a little bit about physics and after watching many hundreds of slick bombs hit their targets, I would say that the programmers have the bomb physics somewhat wrong. Everyone knows that if you drop an object from a high enough altitude that object will accelerate until it reaches terminal velocity, unless of course its retarded somehow. The bombs in the sim. don't necessarily do this. Some of them even slow down as they fall, the GBU-38 comes to mind. I'm sure that you've all seen videos of JDAMs impacting their targets in Iraq and Astan, and the bombs are traveling so fast that you can barely even see them impact and they sound like a jet coming in. Some Mk84s and 82s in the real world aren't even filled with explosives, they're filled with concrete to reduce collateral damage. And because they fall at such a high speed and with such force these concrete bombs have proven themselves to be very effective at destroying targets, especially underground bunkers. This detail of the sim. isn't a huge deal, it's just an observation that someone may want to take a look at if they're concerned about greater accuracy and detail.


Edited by Spudman
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i wouldn't want, one of these dropping on my house :music_whistling:

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I've seen GBU-12's fall at like 550kts.. That isn't fast enough for you?

 

GBU 12s fall at a much faster speed than the 38s. I've actually noticed this as well. The 12s speed up to terminal velocity as the OP stated, but the 38s do slow down considerably. I just thought the 12s were a lot more aerodynamic. I wonder if that's intended.

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Not that I'm doubting you guys, but how the hell did you "notice" this and come to the conclusion that they are slowing down?

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Not that I'm doubting you guys, but how the hell did you "notice" this and come to the conclusion that they are slowing down?

 

Press F6. You can watch your bombs falling and it has location/speed info on the bottom of the screen.

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The JDAMS do not yet have an AFM (i guess due to the complexities involved in designing and tuning a gps guidance control algorithm). This is a known limitation and will hopefully change at some point.

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Thanks a lot guys. I was enjoying dropping bombs and now I need to ask for AFM bombs! zomg it's broken1!!

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I think this problem is apparent for A/A missiles also. I've seen missiles that has run out of energy fall to the ground and still slow down (atleast according to the speed measurement at the bottom, maybe thats whats wrong?)

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I think this problem is apparent for A/A missiles also. I've seen missiles that has run out of energy fall to the ground and still slow down (atleast according to the speed measurement at the bottom, maybe thats whats wrong?)

 

The AFM for A2A missiles has recently been introduced with FC3 and is still in the process of being tuned.

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I think this problem is apparent for A/A missiles also. I've seen missiles that has run out of energy fall to the ground and still slow down (atleast according to the speed measurement at the bottom, maybe thats whats wrong?)

What was the attitude of those missiles? Afaik F6 only shows speed in one plane (forward/backward), so if you have a missile falling at AoA (not nose-diving it) it should show the missile decelerating.

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Thanks a lot guys. I was enjoying dropping bombs and now I need to ask for AFM bombs! zomg it's broken1!!

 

It is just the JDAMs (and i think WCMDs) that experience this behaviour, all other bombs have AFM.

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I think this problem is apparent for A/A missiles also. I've seen missiles that has run out of energy fall to the ground and still slow down (atleast according to the speed measurement at the bottom, maybe thats whats wrong?)

 

The missiles always seem to try and keep positive AoA, even when they're completely burned out. Its rare to see a missile going straight down, at least for me, but when they do, they actually do speed up.

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With the exception of JDAM & WCMD, all the free fall ordnance employed by the Hog has AFM.

 

Not only that but all free fall ordnance performs close enough to reality that you can use real world weapon delivery data and calculators to derive delivery parameters.

 

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  • ED Team
Well I know a little bit about physics and after watching many hundreds of slick bombs hit their targets, I would say that the programmers have the bomb physics somewhat wrong. Everyone knows that if you drop an object from a high enough altitude that object will accelerate until it reaches terminal velocity, unless of course its retarded somehow.

 

This is a simplified explanation. The free-fall bomb dropped from high altitude counteracted air drag dependant on actual Mach and bomb IAS. This parametres change as the altitude changes so TAS you see in F2 view bar can vary as the bomb enters high density air.

 

The second note is for guided bombs that flies using their lift. Lift creates induced drag that is high for the low-aspect wings of these bombs. The effect I mentioned for free-fall bombs is even more noticable.

 

In DCS JDAMs do have the same FM as free-fall bombs, by the way.

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Ничто так сильно не ранит мозг, как осколки стекла от разбитых розовых очков (С) Me

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A Mk82 dropped from 13000 meters accelerated to 1519 kph and started to drop in speed just before it hit the ground.

Should it really go that fast?

And if so, there should be a sonic boom I think...

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Thanks for the explanation Yo-Yo, I wouldn't have thought that the air density could make the bomb braking, rather a slight decrease or a stabilization but I think you have correct data so i trust you!

 

+1 for the "whoooosh" sound when the bomb comes in!

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A Mk82 dropped from 13000 meters accelerated to 1519 kph and started to drop in speed just before it hit the ground.

Should it really go that fast?

And if so, there should be a sonic boom I think...

 

MK 82 and MK 81 was tested to obtain Cd vs M curves and we used results of these tests. Russian bombs curves usually adjusted using so called "charachteristic time" and lag distance for the real bombs as for the other ordnance having available delivering tables.

Ніщо так сильно не ранить мозок, як уламки скла від розбитих рожевих окулярів

There is nothing so hurtful for the brain as splinters of broken rose-coloured spectacles.

Ничто так сильно не ранит мозг, как осколки стекла от разбитых розовых очков (С) Me

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In DCS JDAMs do have the same FM as free-fall bombs, by the way.

 

Why is their terminal velocity so low then? :huh:

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With the exception of JDAM & WCMD, all the free fall ordnance employed by the Hog has AFM.

 

Not only that but all free fall ordnance performs close enough to reality that you can use real world weapon delivery data and calculators to derive delivery parameters.

 

I thought all the ballistics data on bombs was classified? In some -34 manual or something. How'd they get it?

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A bomb is just an oval with fins. Shouldn't a high school physics student be able to derive all the relevant data?

 

Maybe not a high school student, but at the least, but I imagine that someone with some kind of FEA aerodynamics computer program to predict drag coefficients should be able to easily and accurately predict the drag coefficient for something like a Mk-84. We know exactly what the dimensions and shapes are on these bombs, and we know how much they weigh- so we know their ballistic properties.

 

Missiles are a little harder to predict the ballistic properties for, since I believe that the amount of solid rocket propellant inside them is usually classified, but if we make educated guesses, then we should be able to predict their ballistic properties too.

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