Mars is where helicopter design gets weird fast. NASA says testing for its next Mars helicopter has pushed rotor tips to Mach 1.08 in a simulated Martian atmosphere, well beyond the limits used for Ingenuity.
Perseverance’s Ingenuity helicopter flew below about Mach 0.7 to avoid aerodynamic problems on the first powered aircraft flown on another planet. NASA says the next-generation helicopter, being developed as part of the SkyFall project, is being designed for much higher performance.
“The successful testing of these rotors was a major step toward proving the feasibility of flight in more demanding environments, which is key for next-gen vehicles,” said aerodynamicist Shannah Withrow-Maser of NASA’s Ames Research Center in Silicon Valley.
“We thought we’d be lucky to hit Mach 1.05, and we reached Mach 1.08 on our last runs. We’re still digging into the data, and there may be even more thrust on the table. These next-gen helicopters are going to be amazing.”
Mars’ atmosphere is extremely thin, just 1 to 2 percent as dense as Earth’s. NASA says that changes how aircraft operate, and it puts the sound barrier at a lower speed, around 869 kilometres per hour on Mars, compared with 1,225 kilometres per hour at sea level on Earth.
Ingenuity arrived on Mars with the Perseverance rover in January 2021. It was originally planned to make five flights, but it flew 72 times before crashing in 2024. The crash was not caused by its flight system, but because it could not gauge its distance from the ground while descending.
“If Chuck Yeager were here, he’d tell you things can get squirrely around Mach 1,” said engineer Jaakko Karras of NASA’s Jet Propulsion Laboratory.
“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.”
To test the new designs, JPL used a chamber with pressure lowered to simulate Mars’s atmosphere. The team tested a three-blade rotor and a two-blade rotor while monitoring them from a nearby control room.
The three-blade design spun at up to 3,750 rpm, sending the tips to Mach 0.98. The two-blade rotor, which had longer blades, reached the same Mach 0.98 at about 3,570 rpm. For comparison, Ingenuity’s rotor blades never exceeded 2,700 rpm.
Engineers then switched on a fan inside the chamber to create headwinds. NASA says that pushed rotor tip speed to Mach 1.08.
NASA says the higher speed increases lift by about 30 percent, allowing the next helicopter to carry heavier payloads and more science instruments.
If all goes to plan, SkyFall will launch near the end of 2028 carrying three helicopters, according to NASA. The agency says they will scout human landing sites and map water ice beneath the surface of Mars.
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