Why would Astrotrain need to jettison weight while in space?

The Decepticons have used him for transport countless times. After escaping following the Battle of Autobot City, Astrotrain requests they lighten his burden. Why? Intro Music by Tony Bacala of www.tfw2005.com Background Music: https://www.youtube.com/user/teknoaxe Song used "Aerobatics in Slow Motion" Licensed under Creative Commons: By Attribution 4.0 License http://creativecommons.org/licenses/by/4.0/ Support me on Patreon: https://www.patreon.com/rodimusprimal Follow me on: Facebook: https://www.facebook.com/rodimusprimalfanshow Twitter: https://twitter.com/rodimusprimal Twitch: https://www.twitch.tv/rodimusprimal1