Transition Drive

Transition Drive can be described as 'Hypothetical FTL', at least considering the role it can play. Although it does allow the ship to move with FTL spead, it can only serve the role of STL engines, which means travel between planets, but not between stars.
WIth enough power, the ship equiped with Transition Drive can THEORETICALLY jump from system to system. Practically however, providing enough power for a 10ly jump would require all power produced by a middle-sized star captured by a Dyson sphere... within few minutes of work. Which adds completely new meaning for a word 'uneconomical'.