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Old 01-18-2019, 01:17 PM   #1
Nealius
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Default Help with Mk20 release parameters

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?
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Old 01-18-2019, 03:29 PM   #2
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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.

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Old 01-19-2019, 01:20 AM   #3
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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?
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Last edited by Nealius; 01-19-2019 at 02:30 AM.
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Old 01-19-2019, 05:30 AM   #4
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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.
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Old 01-19-2019, 07:54 AM   #5
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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.
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Old 01-19-2019, 10:41 AM   #6
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its been stated in one of Wag's video : cbu99 and mk20 are the same weapons with different cannister
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Old 01-19-2019, 11:00 AM   #7
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Quote:
Originally Posted by Goa View Post
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/c...rations-44.htm
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Old 01-19-2019, 11:00 AM   #8
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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
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Old 01-19-2019, 09:24 PM   #9
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Quote:
Originally Posted by Nealius View Post
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.
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Old 01-20-2019, 12:13 PM   #10
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If there's such a difference in fuzing between the two already then why do we even have fuze options in the cockpit?
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