Very little. By one estimate jets burn about 10% of fuel to reach _cruising altitude_. [1] Unless the catapult got you up to altitude it would not help much. C

Very little. By one estimate jets burn about 10% of fuel to reach _cruising altitude_. [1] Unless the catapult got you up to altitude it would not help much. Catapults solve a different problem, namely taking off from a short runway. [1] https://www.quora.com/How-much-fuel-is-burned-during-take-off-until-an-aircraft-reaches-normal-cruising-speed-Is-this-the-most-fuel-consuming-part-of-the-flight https://www.quora.com/How-much-fuel-is-burned-during-take-of...