President Donald Trump wants the U.S. Navy to use steam-powered catapults – technology from the 1950s – aboard its aircraft carriers, instead of the electromagnetic systems the fleet is currently using.Trump’s national security memorandum orders defense officials to formulate a plan for the change in future USS Gerald R. Ford-class aircraft carriers. The move is expected to cost taxpayers hundreds of millions of dollars, Reuters reported.The president’s order follows his simmering dissatisfaction with the Electromagnetic Aircraft Launch System, known as EMALS, going back to 2017."Billions of dollars more they spent on electric catapults and ​they're not good. They're not nearly as good, too complex," Trump said at a defense summit in Pennsylvania last month.While steam catapults have been successfully used for decades, the Navy began using electromagnetic ones with its latest aircraft carriers, starting with the USS Gerald R. Ford in 2017.Reverting to steam catapults is “illogical, inefficient and a waste of money,” said retired Rear Adm. Mark Montgomery, a senior fellow at the Foundation for Defense of Democracies, The Hill reported. Montgomery said EMALS “reduce wear and tear on aircraft by providing smoother acceleration.”Can't see our graphics? Click here to reload the page.When the Navy selected ‌EMALS ⁠in 2009, it said it would lower overall lifecycle costs, require less maintenance than steam catapults and generate less physical stress on carrier-based aircraft, Reuters reported. The system, also selected by France's navy, had initial troubles but has since completed thousands of launches.In a Time magazine interview, Trump cited a conversation with a Navy catapult officer who criticized the electromagnetic system. Trump said steam catapults should be used because "the digital costs hundreds of millions of dollars more money and it’s no good.”How do the catapult systems work?Jets on aircraft carriers use catapults to attain take-off speed from flight decks, which are too short for launches without assistance. In essence, catapults shove jets from stationary positions to takeoff speeds over a very short distance.Steam catapults use high-pressure steam forced into two parallel cylinders below the flight deck. On later carriers, the cylinders are about 300 feet long. Each cylinder contains a piston.The steam pressure drives the pistons forward. The pistons are connected to a launch shuttle, a moving sled in a track on the flight deck.When released, the launch shuttle pulls the aircraft down the flight deck fast enough for it to take off.The U.S. Navy began using steam catapults in 1954, with operational trials aboard the USS Hancock.EMALS use electricity – lots of it – instead of steam to launch aircraft.They use linear induction motors – electric motors that produce motion in a straight line, instead of in a rotational motion. On modern-day aircraft carriers, they’re powered by nuclear reactors.Since EMALS need large amounts of power, energy for the motors is stored before aircraft are deployed. During a launch, the motors send a burst of power through a long row of electromagnetic coils beneath the flight deck.The magnetic field pulls a launch shuttle down the track, bringing the aircraft with it. A computer controls the force, so the aircraft reaches sufficient takeoff speed.Which Navy ships are affected?The alteration will ​start with the USS Doris Miller (CVN-81), the fourth ship of the Gerald R. Ford class. The keel for the Miller will be laid by the end of 2026, and the ship is expected to be delivered in February 2034.The first three Ford-class ships – the Ford, the USS John F. Kennedy (CVN-79) and the USS Enterprise (CVN-80) will keep the electromagnetic systems already installed. The Ford had completed 36,863 EMALS launches as of March 2026, according to Pentagon documents, Reuters reported.Trump ordered defense officials to produce a catapult replacement plan within 60 days of his memorandum.Source: USA TODAY Network reporting and research; Reuters; U.S. Navy; U.S. Naval Institute