NASA Pushes Mars Helicopter Rotors Past the Speed of Sound for the First Time Ever
Arthur T Knackerbracket writes:
These extreme speeds are necessary to generate enough lift in Mars' ultra-thin atmosphere, which is only about 1% as dense as Earth's. The planet's atmosphere also lowers the speed of sound to roughly 537 mph (864 km/h), compared to about 767 mph (1,235 km/h) at Earth's sea level. The rotors were jointly developed by NASA and AeroVironment as part of Project SkyFall, a proposed mission to deploy multiple airborne exploratory rotorcraft across Mars. The mission, currently targeted for December 2028, would transport three next-generation Mars helicopters aboard a spacecraft to the Red Planet. Once the spacecraft lands on Mars, the helicopters would deploy to different regions of the planet for independent exploration missions, using the landed spacecraft as a communications and operational base.
NASA had a great run with the Ingenuity Mars Helicopter, but we are asking these next-generation aircraft to do even more at the Red Planet," said Al Chen, Mars Exploration Program manager at JPL. That's not an easy ask. While everything about Mars is hard, flying there is just about the hardest thing you can do. That's because its atmosphere is so incredibly thin that it is hard to generate lift, and yet Mars has significant gravity."
The biggest obstacle to airborne exploration on Mars has always been the planet's ultra-thin atmosphere, which requires extremely high rotor speeds to generate sufficient lift. Ingenuity achieved this with rotor tip speeds of around Mach 0.7 as a safety precaution. However, despite its success, the entire craft was only about the size of a tissue box, weighed 1.8 kg (4 lbs), and did not carry a payload, so it did not carry any scientific or communication equipment. The obvious solution was larger aircraft, but bigger craft create more drag and require significantly more thrust to remain airborne. That thrust could theoretically be achieved at near-supersonic rotor speeds, but rotor blades would normally be at risk of structural failure under such extreme conditions, until now.
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 Shannah Withrow-Maser, a NASA aerodynamicist and member of the test team. 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."
NASA's new supersonic rotor technology could enable significantly larger exploratory aircraft capable of carrying bigger batteries for longer missions, more advanced scientific instruments, and improved communication systems. NASA says Project SkyFall's helicopters will perform low-altitude aerial exploration and scouting missions, gathering scientific data while helping pave the way for future robotic and potentially human missions to Mars.
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