Halo: Reach
As the latest game in the franchise, Reach offers us the most up to date data. Ironically, it'd be one of the first events in chronological events.
Source:
http://www.youtube.com/watch?v=nAtPyUN9QRM
Our first display of firepower comes at 2:16, when we're told this:
First things first. The MAC round, which is seen firing at Spire One. The tower, just eyeballing it, looks to be 288 meters tall. We then see the Grafton fire its shell, it creates a fireball that is roughly 45 meters in radius (90 diameter).Air Control: Frigate Three One Eight heavy is inbound, and MAC rounds have been authorized.
Jorge: MAC rounds?? In atmosphere??
Noble 1: One way to get their attnetion! Hang on to your teeth people!
*Grafton fires its MAC and destroys the tower. Seconds later, we see a blue plasma beam strike the ship and tear through it like tissue paper*
DOT: New Contact. High-tonage.
Jorge: No. No! Somebody tell me this ain't happening!
Air Control: UNSC frigate Grafton, do you copy?
Noble One: The Grafton is dust! We need to get out of here NOW!
Here's the BLU-82B:
http://www.youtube.com/watch?v=_upy14pe ... re=related
Eyeballing a picture of some men on one, the BLU is about six meters tall. The parachute holding it appears to be about 6 meters in size as well. The parachute drops downwards and then explodes, creating a fireball about 9-10 times larger than the parachute was. Going with nine, that gives us a blast radius of roughly 27 meters (54 diameter). The BLU is a 15,000 pound bomb, or 7.5 tons.
This would make the MAC's round between the MOAB (11 tons) and the US estimated yield of the FOAB (16.5 tons, as opposed to the 44 tons they claim) for about 13 tons more or less. This would be rather telling for the shielding capabilities of the Covenant, assuming that the same yield is used against them.
The second important bit of dialogue comes later:
So to destroy a super carrier, they need a nuke. Keep in mind that we did see a UNSC frigate during MISSION: Uppercut. And yet oddly enough, they didn't have anything that equaled the power of a nuclear weapon.Kat: That thin's crushing us and we're waiting for backup? They'll be backing up a graveyard.
Carter: All our nukes are either out-system or went down with the ships that carried them. You're preaching to the converted.
Unfortunately, we don't know what they mean by "nukes". We know of 30 megaton mines used in GoO, but let's keep in mind that most nuclear weapons are probably missiles. A mine is just a single bomb and can therefore afford to be much bigger because it doesn't need a large rocket to propel it against the enemy.
Now let's think about a nuclear missile. This is the US's W80 nuclear missile designed for both stealth and speed:
http://en.wikipedia.org/wiki/W80_(nuclear_warhead)
It has a variable yield of 5-150 kilotons and is probably what we're looking for in a nuclear missile. According to Atomic Rockets, most weapons would probably be 1 kiloton for a space based nuclear missile. Given that the weapons that impacted the other ship were in the double digit ton range and managed to punk a smaller ship, larger ships having a handful of kilotons is probably a reasonable guess.
Also, found this:
http://www.5596.org/cgi-bin/nuke.php
Pretty cool.