After watching a video about mods of the past, i remembered about this one.
Basically, this mod allowed structures to act like flying entities. All the player need to do is place a technical-block that would also act as steering for the mod to "convert" the structure (with a size limit, of course) into a flying airship. Other variations of this mod also allowed terrestrial and watercraft to be made.
Demo of the original mod:
https://youtu.be/CIJYcLLRw7I
Fly your creations in the Minecraft world!
Please use the official thread for issues and updates
http://www.minecraftforum.net/topic/488434-173-zeppelin-wip/