That's essentially a 4 grain Shuttle booster as the 5th grain was a spacer (ala Cesaroni!). I believe you're talking in the double letter ranges... something like WX I've heard.

W

I was thinking the Mother of all Clusters.
1 Trillion H999's

If you consider the alphabet to wrap around (I.E. x..y..z..aa..ab..ac..), the SRBs would be a 1.24*10^9 AD 10 million using CTI notation (1.24*10^9 newton second AD10000000). Assuming I did the math right of course...

Size dosen't really matter, does it, when you're talking almost a full load? And I thought the three grain load was special. Yikes!!! That really is an incredible picture.

4 grain is the standard Shuttle load - the full load for Ares will be a 5 grain. Here's a video of a static test of the 5 grain:

http://www.youtube.com/watch?v=E3cPKgFKe0Y&feature=related

And some high-speed video up the core showing the igniter firing:
http://www.youtube.com/watch?v=CGImLZpQDwY&feature=related

4 grain is the standard Shuttle load - the full load for Ares will be a 5 grain. Here's a video of a static test of the 5 grain:

http://www.youtube.com/watch?v=E3cPKgFKe0Y&feature=related

And some high-speed video up the core showing the igniter firing:
http://www.youtube.com/watch?v=CGImLZpQDwY&feature=related

Wow! That core ignition video is cool. I'm surprised it seems the ignitor seems to have burned out (or maybe it's obscured by smoke?) before the core really catches.

It must be an extremely high speed video - watch how quickly it ignites on the main video to compare. I do wonder whether the darkening is more a product of the igniter burning out, or whether it is simply because the igniter flame is being obscured by smoke. It's definitely an awesome video though - I wish I could see a comparable view for some of our motors (though it would be quite hard to get).