USN Thermal Protection on Bombs (green vs. gray)

[Nealius]

TL;DR TImeline of Navy thermal protection on Mk80 series

1967 - Forrestal Fire

c.1972 ~ c.2001 - thermal coated bombs were green (two yellow bands)

c.2002 ~ c.2003 - gray color starts being introduced, but green bombs remain in service (two yellow bands on both)

c.2004 ~ present - gray color fully replaces green (two yellow bands, sometimes three yellow bands)

Long Version

Most of us Naval Aviation nerds know about the Forrestal Fire in 1967, which spurred the USN to research bomb cookoff times and develop a thermal coating for the Mk80 series bombs. However, there's a misconception that thermal protection and a gray color are mutually inclusive, and that all Navy bombs after 1967 should be gray. The color of the bomb body does not indicate thermal protection. The number of yellow bands on the nose of the bomb indicates whether it has thermal protection or not (US Navy Academy document; "Chapter 9 Aircraft Ordnance").

1 yellow band = no thermal protection

2 yellow bands = thermal protection

3 yellow bands = ???? (I have seen this on post-2004 images but cannot find a reference explaining the third band)

So what's the timeline? I cannot find a written resource, but a long search through images on seaforces.org will give a rough timeline for when to use green bombs or gray bombs.

1970; no thermal protection (note single yellow band)

1972; thermal protection begins service (note the inboard bombs have no thermal protection, while the outboard bombs do)

1978, 1982, 1991, 1997 respectively; thermally protected bombs in service are still green

2002~2003; the gray color is introduced with some aircraft loaded with all-green, others loaded all-gray, and others with mixed loads

2004 ~ present; gray seems fully integrated, sometimes seen with three yellow bands instead of two

In conclusion

If you're flying pre-1972, leave bombs default. 

If you're flying 1972-2002ish, use the green bomb textures: 

If you're flying post-2002, use the gray bomb textures (either the in-game ones or the various community mods on User Files):

And on that note, anyone know what three yellow bands means? 

 

 

 

 

 

[ngreenaway]

Maybe this source can help you on three bands?

Chapter 9: aircraft ordnance

 

I found this diagram in it:

Edited March 4, 2022 by ngreenaway

[Nealius]

Thanks! Same document I used to source the two yellow bands. I'm surprised they mentioned it in the figures and not in the text, but that explains why I couldn't find it using the search function.

Apparently BLU-110/111 is just a different explosive filler that is "thermally insensitive." I guess that makes them safer than the standard Mk80s that only have external thermal protection.

[ngreenaway]

Just needed a second set of eyes, I guess

 

I'm sure there's blu110/111 documentation that may discuss further 

[Frederf]

The three bands seems to be reserved simply to visually differentiate the BLU-111/110/117 warheads from their Mk-82/83/84 equivalents. As far as I can tell It can also be taken to mean the use of PBXN-109 instead of Comp H6 as all the USN BLU-100 series bombs have the more insensitive filler.

[Vapor_12]

This is correct, but not "also" so much as "does". Naval Bomb Live Units use PBXN, and MK series munitions use Tritonal. These are, as far as I am aware, a rule. Marks are always Tritonal and BLUs (including penetrators like 109 common in Air Force inventory) are PBXN.