The Mk IV was a revolutionary step forward. It was designed from the ground up to be a hybrid space/atmospheric versatility fighter. With nods to the Mk II it had three engines, two KEWs and one pilot. The biggest change was a force induction hood that surrounded the cockpit letting air straight into the engines this Viper was much more efficient in atmosphere burning only a quarter of the Tylium fuel needed to do the same run in a Mk II. Vents were added to the wings that could serve three purposes; more atmo pumped into systems, an extra lift duct or a aerospace booster brake. The last major addition was a bomblet bay located between and slightly below the lower engines.