Delta IV is a partially active expendable launch system in the Delta rocket family. It was formerly operated by Boeing, and is now operated by United Launch Alliance (ULA). Delta IV is now only launched in 1 variant: Delta IV Heavy. The other 4 remaining variants of Delta IV that have been already retired are Delta IV Medium; Delta IV Medium+ (4,2), (5,2), (5,4). The first digit in the bracket stands for second stage diameter in meters and the other digit stands for number of SRBs. The vehicle operates out of Space Launch Complex 37B at Cape Canaveral Air Force Station and Space Launch Complex 6 at Vandenberg Air Force Base. There was also Delta IV Small _ variant considered with Delta-K second stage that was used on Delta II.

I recommend turning on "Advanced tweakables" in KSP settings.

To download each variant of Delta IV, go to the "Files" section.

Also Don’t forget to download the flags for Delta IV in the "Files" section.

Here are my other projects.

Delta IV Medium, Medium+ (4,2), Medium+ (5,2), Medium+ (5,4), Heavy

Common Booster Core

4-meter Delta Cryogenic Second Stage, 5-meter Delta Cryogenic Second Stage

GEM-60

Delta IV Medium
T-0:00:05 - Main Engine Ignition
T-0:00:00 - Lift Off
T+0:02:12 - Main Engine Cut Off
T+0:02:15 - First Stage Separation
T+0:02:20 - Second Engine Ignition
T+0:02:42 - Fairing Deploy

Delta IV Medium+ (4,2)
T-0:00:05 - Main Engine Ignition
T-0:00:00 - Solid Rocket Boosters Ignition
T-0:00:00 - Lift Off
T+0:01:06 - Solid Rocket Boosters Jettison
T+0:02:12 - Main Engine Cut Off
T+0:02:15 - First Stage Separation
T+0:02:20 - Second Engine Ignition
T+0:02:42 - Fairing Deploy

Delta IV Medium+ (5,2)
T-0:00:05 - Main Engine Ignition
T-0:00:00 - Solid Rocket Boosters Ignition
T-0:00:00 - Lift Off
T+0:01:06 - Solid Rocket Boosters Jettison
T+0:01:57 - Fairing Deploy
T+0:02:12 - Main Engine Cut Off
T+0:02:15 - First Stage Separation
T+0:02:20 - Second Engine Ignition

Delta IV Medium+ (5,4)
T-0:00:05 - Main Engine Ignition
T-0:00:00 - Solid Rocket Boosters Ignition
T-0:00:00 - Lift Off
T+0:01:06 - First pair Solid Rocket Boosters Jettison
T+0:01:07 - Second pair Solid Rocket Boosters Jettison
T+0:01:57 - Fairing Deploy
T+0:02:12 - Main Engine Cut Off
T+0:02:15 - First Stage Separation
T+0:02:20 - Second Engine Ignition

Delta IV Heavy
T-0:00:05 - Main Engine Ignition
T-0:00:05 - Boosters Ignition
T-0:00:00 - Lift Off
T+0:01:55 - Boosters Jettison
T+0:03:05 - Fairing Deploy
T+0:03:20 - Main Engine Cut Off
T+0:03:23 - First Stage Separation
T+0:03:28 - Second Engine Ignition

Calculated with full thrust.