Help with Mk20 release parameters

[Nealius]

This is my first time using the Mk20s, after having used the Mk82 and Mk83 series bombs extensively and the CBU-99s a couple of times. For some reason I am not getting a valid CCIP cross in the HUD until I am extremely low over the target, like so:

 

 

My fuze settings are: MFUZ VT, EFUZ INST, HT 1500.

 

Had these been Mk80 series bombs, or CBU-99s, I would have had a cross visible in the HUD long before this point. I finally managed to drop some, but had to dive at 45 degrees and only got about 1 second of track time before the pipper crossed the target. What am I doing wrong?

[Tholozor]

Normal release parameters for the Rockeye series are between 25°-30° dive angle at an altitude of 2500ft AGL. You're far too high above the target for a valid release.

 

[Nealius]

Something isn't adding up. In the Hornet, Mk20 and CBU99 release with different parameters despite having the exact same canister. In the Harrier, I can release Mk20s from as high as I can Mk80 series bombs in both the Harrier and the Hornet. What's special about the Mk20 that makes it different from all the other low-drag bombs?

Edited January 19, 2019 by Nealius

[Frederf]

Some Rockeye II weapons are fuzed to dispense a timed interval after release instead of a proximity distance from surface. The post-dispense and pre-dispense ballistics are different (assume post-dispense much more drag).

 

So even the same weapon dispensing (or predicted to dispense) at different heights will have a different composite trajectory.

[Nealius]

Could that explain why the CBU-99 behaves differently with the same settings? I get earlier CCIP cuing and it appears that they burst lower than the Mk20, though I haven't specifically tested to see if they actually do.

[Goa]

its been stated in one of Wag's video : cbu99 and mk20 are the same weapons with different cannister

[Nealius]

its been stated in one of Wag's video : cbu99 and mk20 are the same weapons with different cannister

 

Mk20, CBU-99, and CBU-100 all use the same canister:

http://navyaviation.tpub.com/14313/css/Mk-20-Mods-Cbu-99-Cbu-100-Bomb-Cluster-Configurations-44.htm

[Hog_No32]

Before the last update I expended Mk20‘s on basically every flight and they always worked neatly. Settings were CCIP, MFUZ VT, EFUZ INST, HT 1500.

 

My attack profiles were usually:

- low-level ingress (<100 ft AGL), speed ~M0.9, pop up 4-3NM to the target to about 3000-4000ft and then a 20-30° dive onto the target. That is what I mainly used against an SA-6 site.

Or about the same dive angle but from a bit higher altitude (5000-8000) when attacking an undefended convoy.

 

To be honest I am not 100% sure I did use them after the update last wednesday...I was busy exploring the HARM too much ;)

[Frederf]

Could that explain why the CBU-99 behaves differently with the same settings? I get earlier CCIP cuing and it appears that they burst lower than the Mk20, though I haven't specifically tested to see if they actually do.

 

Two otherwise identical Rockeye II will have different composite trajectory if they have different fuzing. Due to the possible fuzing options there are thousands of possible fuze settings resulting in practically any dispense height and each will have a different trajectory shape even if all were released under identical conditions.

 

There are more choices for weapon config than can be changed in the cockpit. The pilot has really four choices: nose wire, tail wire, both, or neither. None of the Rockeye's fuzes interface with the airplane electrically.

 

If you want to compare the weapons you have to discover how they're being fuzed.

[Nealius]

If there's such a difference in fuzing between the two already then why do we even have fuze options in the cockpit?

[Frederf]

There are two ideas: fuze setting and fuze information.

 

A setting is a choice by the pilot. The equipment can work in more than one way and by making this choice the actual behavior will be different. Information is faithful reporting to the airplane details about the equipment. If wrong information is reported to the airplane then it will make predictions based on wrong data.

 

The pilot enters information about the unchangeable nature of the weapon into the airplane so it knows how to give all sorts of aiming and warning cues. This includes what kind of weapon it is, what fuze is installed on it, what fuze settings are set.

 

Then pilot can make choices which for a wire-based arming is limited to pulling the nose wire, tail wire, both, or neither.

 

If you ask why does pilot enter "HOF 1800' " into airplane if the fuze is going to burst at 1800' regardless of the data entry, the answer is because it changes how you aim the weapon and are notified about certain conditions.

[Nealius]

So basically, the weapons in the sim have a hard-coded fuze. If we don't set our cockpit fuze settings to match the sim coded fuze settings, then things get wonky. But we're not told what fuze settings the sim has coded....

 

Is that correct?

[Tholozor]

Right now the Mk20's height of function is hard-set to 1500' AGL until it's updated to accept different a different height-of-function. Normally this would be set on the ground on the canister itself, like the laser code on a Paveway LGB. The pilot would then input the canister's pre-set height-of-function into the Stores page to obtain the correct release parameters. However since the Hornet doesn't have this kind of setup in place, they have to code it in that the Stores page can tell the canister what its fuze it set to, just like the LGBs (The F-5E did it right, those should only be able to be set on the ground, and not on-the-fly).

Edited January 21, 2019 by Tholozor

[Nealius]

Is the CBU-99 also hard-set to 1500' at the moment?

[Ramsay]

Is the CBU-99 also hard-set to 1500' at the moment?

 

AFAIK yes.

 

"DCS World\CoreMods\aircraft\AircraftWeaponPack\cluster_bombs.lua"

 

CBU_99 =
{
...
   control = 
   {
       default_delay	    = 1.2,
default_open_height = 457,
   },
...
}

 

457 m = 1500 ft

[Rukus]

Open Beta Issue/Question

 

Hello...Im not sure where i would post questions regarding the open beta.

 

 

I was wondering if anyone can verify if the cluster bombs are working as they should in the Open Beta with the F18C. I have no issue with the release version, but when i drop them now they seem to just hit the ground and never pop open at the height that i set for dispersal.

 

 

Not sure if the procedure has changed or im just screwing something up but it does work properly in the release version

[Svsmokey]

Seems i've read of the mk20 or the cbu99 acting differently...try the other

[Svsmokey]

This is the thread i was thinking of...

 

https://forums.eagle.ru/showthread.php?t=230033

[CoBlue]

Hello...Im not sure where i would post questions regarding the open beta.

 

 

I was wondering if anyone can verify if the cluster bombs are working as they should in the Open Beta with the F18C. I have no issue with the release version, but when i drop them now they seem to just hit the ground and never pop open at the height that i set for dispersal.

 

 

Not sure if the procedure has changed or im just screwing something up but it does work properly in the release version

No bombs work correctly in OB if you release them bellow 1500' AGL....not even sneakeyes.

[CoBlue]

Bombs don't explode bellow 1500' AGL?

 

Latest OB, no mods. PG & Caucasus. Attached trk.

For cluster-bombs Mk-20.

Mode: CCIP, Mfuze: nose, Efuze: instant.

VT is set below 1500, no bomb will explode.

 

For MK-82, 82Y, 83, 84.

Mode: CCIP, Mfuze: nose, Efuze: instant. No bomb will explode bellow 1500 AGL.

You can use low altitudes on all other airplanes like A10C, AV8B, M2K, while only F-18 has a 1500' limitation?

Edited January 28, 2019 by CoBlue

[javelina1]

set your bomb for 1500 feet. I believe right now it's hard coded to explode at 1500 feet. I used the same settings as you, but had the bomb at 1500. There's a thread mentioning something about this.

[Supertaquito]

CBU BUG. No longer bursting.

 

My MK-20s are not bursting at the HT I select after setting the MFUZ to VT. I have dropped CBUs before so I know I am not forgetting some silly setting, but they just stopped working after the latest update and they no longer burst so the bomb body just falls inert regardless of height, speed, and angle of dive.

 

I've tried the stock CBU training mission to see if I had indeed forgotten something and the problem persists even after following the instructions, it just looks like I am dropping duds with no dud queue on the HUD, but all other bombs work fine.

 

 

My workflow is as follows:

 

 

 

Master switch on.

 

A2G Mode selected.

RE Selected on DDI.

MFUZ Option for VT.

HT Set to 1500 to match physical fuse on the MK-20.

Altimeter set to RDR.

Height warning set to 1500 Feet.

20 to 30 dive angle at no more than 500 knots.

Release at different altitudes of greater than 1500 feet and lesser than 3000 feet.

 

 

Thanks for any insight!

[Mr_Burns]

I think this must be a simple 'user' issue, I cannot get Mk82 (82XT) to drop without going below the pull up point.

 

 

CCIP NOSE OFF RET

 

 

I cannot get an impact point at all!!

[Eagle7907]

My MK-20s are not bursting at the HT I select after setting the MFUZ to VT. I have dropped CBUs before so I know I am not forgetting some silly setting, but they just stopped working after the latest update and they no longer burst so the bomb body just falls inert regardless of height, speed, and angle of dive.

 

I've tried the stock CBU training mission to see if I had indeed forgotten something and the problem persists even after following the instructions, it just looks like I am dropping duds with no dud queue on the HUD, but all other bombs work fine.

 

 

My workflow is as follows:

 

 

 

Master switch on.

 

A2G Mode selected.

RE Selected on DDI.

MFUZ Option for VT.

HT Set to 1500 to match physical fuse on the MK-20.

Altimeter set to RDR.

Height warning set to 1500 Feet.

20 to 30 dive angle at no more than 500 knots.

Release at different altitudes of greater than 1500 feet and lesser than 3000 feet.

 

 

Thanks for any insight!

 

 

I noticed you didn't mention the EFUZ. For some reason, you have to set the EFUZ to Inst now. I didn't have to do it before, but now you do. Mine work that way. :dunno:

[CoBlue]

Can someone from ED please please clear this up?

 

Why are Mk-20 hard-coded for 1500' AGL?