reported CCIP with MK-84 and MK-83 falls short

[Harker]

Seems like the CCIP solution is not calculated correctly. A heavier bomb will have more inertia. All in all, I think that the effect of air resistance is still higher in most cases. Whether the piper cross moves up or down when selecting a heavier bomb, would of course depend on the release parameters; it's a simple kinematics problem that the MC needs to solve.

Edited October 22, 2019 by Harker
Edited because I'm stupid sometimes

[Tom Kazansky]

It is not the gravity. It is the lack of drag(-difference). In DCS all 3 slick bombs fall the same way, like they would IRL-vacuum.

 

 

 

Even a feather would hit DCS's Mk82-CCIP in vacuum. ;)

 

 

So ED could do a quick work around and use the MK82-CCIP for Mk83 and Mk84 and/or include the correct drag.

Edited October 22, 2019 by Tom Kazansky

[TeamMaximus]

Seems like the CCIP solution is going the opposite way (moving the CCIP cross higher with heavier bombs). It's not as simple as that, because a heavier bomb will experience a higher gravitational force, but at the same time it'd have more inertia. All in all, I think that the effect of gravity is still higher in most cases. Whether the piper cross moves up or down when selecting a heavier bomb, would of course depend on the release parameters; it's a simple kinematics problem that the MC needs to solve.

 

 

As @Tom Kazansky said, gravity is a constant, the standard gravitational acceleration value for Earth is: gn = 9.80665 m/s2 (discounting latitude and altitude, plus a host of other really, really small influences). What this means is that the Earth's mass exerts the same pull on a 500 lbs bomb as it does a 2000 lbs bomb. The only difference between the two in this thread is the size, and therefore the drag induced by increased frontal area of the larger weapon (Mk84) as the bomb falls.

[Harker]

Duh, for some reason I treated like a shot with a fixed initial force rather than a release with a fixed initial velocity... Go figure. I shouldn't comment when I'm right after work and my head is buzzing. You're right, air resistance should be the deciding factor here, as would be inertia, although I don't know how much the latter matters. Inertia should counter air resistance a little bit, at least and it would matter more for deviations due to wind. I'm guessing that the drag coefficients take this into account.

Edited October 22, 2019 by Harker

[Robin_Hood]

Actually, the bomb mass does matter whenever you have air resistance. Basically, two things will have opposite effects: the shape of the bomb will matter in how much air is actively trying to slow the bomb (therefore, the drag coefficient), but at the same time, the mass will matter in how "difficult" it is for the air to slow it down.*

 

So, the bigger the bomb, the shorter it will impact; the heavier it is, the longer it will impact. Knowing which is the deciding factor for our Mk 80 series would need actually crunching the numbers (or perhaps it can be deduced from delivery tables). But with much heavier bombs that still keep a relatively optimized aerodynamic shape, I wouldn't be surprised to see them impact longer.

 

* To explain it a little more, drag force does not depend upon the mass of the object, while gravity does ; so with F = m.a, we have m.a = m.g - k.v² (assuming a drag force in v², although it does not matter here), and therefore: a = g - v².k/m. Therefore, the higher k is (which dépends mostly on the shape), the more the object is slowed, and the higher m, the less it is slowed.

[Tom Kazansky]

It should be like that.

 

 

At the moment DCS Mk8x's seem to fall the same trajectory (impact wise).

 

 

Since their CCIPs are different the Mk83 falls short of its CCIP and the Mk84 falls even shorter than its CCIP.

[BIGNEWY]

Tested with MK-82 MK-83 and MK-84

 

Mk- 84 Falling short is reported.

 

MK-83 MK-82 Seemed ok to me

 

some difference depending on which pylon they came from.

[QuiGon]

That fits my observations as well. I've never really used the Mk-82, so I can't say much to that, but the Mk-83 always worked fine with me, although I haven't used it much lately. The Mk-84 definitely falls short which I've personally expierenced as late as last week.

[Tom Kazansky]

Tested with MK-82 MK-83 and MK-84

 

Mk- 84 Falling short is reported.

 

MK-83 MK-82 Seemed ok to me

 

some difference depending on which pylon they came from.

 

 

thanks for the screenshot.

 

 

 

I tested again with Mk82, Mk83 and Mk84 all from same position in active pause.

 

 

did 100 drops with time scale 4x.

 

 

got a nice tight impact circle where it did not matter which of the three types I released.

 

 

since the three CCIP(-lines) have different lenght, my conclusion is that they don't fit to this one (similar) trajectory.

 

 

 

If active pause is the problem, my results may not show how it is. But if not, there is an issue.

 

 

I will now go and drop some bombs while flying (with timescale 1/2) and will report the results.

[Tom Kazansky]

after doing those tests while flying (without active pause) my results are not the same. The bombs (Mk83 and Mk84) impact much closer to the target.

 

 

Mk82 hit 100% (length wise).

 

 

Mk83 hit quite close (just a little bit short)

 

 

Mk84 hit a bit shorter but still close to the target.

 

 

Well, it seems to me, that my conclusions from active-pause-testing don't show exactly how it is while flying.

 

 

But it still seems, that the heavier the bomb the shorter it falls.

[Nagilem]

Completed some bombing runs on the north end of a helicopter pad last night with Mk 83s. I started my run at 25k feet and pickled at about 10k in a 37 degree dive. While I can admit I may not have been exact with the piper, the bomb pairs consistently fell short - like the piper is on the building, but the bombs hit on the plane side of the helicopter pad.

[Raviar]

@BIGNEWY I believe the issue still exists on Hornet at least

[BIGNEWY]

yes its reported, probably due to the QNH issue. 

 

thanks