The original speed that a ship travels. The speed and distance decides the travel time between planets. Ship speed is increased above base with every level of engine researched. * Combustion Drive increases the speed of ships using a combustion engine by 10% of base for each level researched. * Impulse Drive increases the speed of ships using impulse engines by 20% of base for each level researched. * Hyperspace Drive increases the speed of ships using hyperspace engines by 30% of base for each level researched.