Engineers at NASA's Jet Propulsion Lab make a breakthrough in rotor technology

Because of this thin atmosphere, helicopters flying on Mars must spin their rotors faster than on Earth to generate lift, and heavier vehicles need more lift than lighter ones. The rotors on the SkyFall helicopters will also be larger than those on Ingenuity, which spun its blades at 2,700 rpm, already 10 times faster than passenger helicopters on Earth. But engineers were careful to design Ingenuity not to spin its carbon-fiber rotors faster than the speed of sound out of concern that exceeding Mach 1 (roughly 540 mph on Mars) might cause the blades to shatter. “If Chuck Yeager were here, he’d tell you things can get squirrely around Mach 1,” said Jaakko Karras, the rotor test lead at JPL, in a NASA press release. “With that in mind, we planned Ingenuity’s flights to keep the rotor blade tips at Mach 0.7 with no wind so that if we encountered a Martian headwind while in flight, the rotor tips wouldn’t go supersonic. But we want more performance from our next-gen Mars aircraft. We needed to know that our rotors could go faster safely.” Recent testing at JPL pushed rotors past the speed of sound without damaging them, NASA announced Thursday. The rotor tips reached a top speed of Mach 1.08 in a test chamber simulating Mars’ atmosphere. Engineers didn’t know for sure what would happen to the rotors, so they lined part of the chamber with sheet metal to shield it from damage if the blades broke apart during the supersonic experiment, according to NASA.