The company advertises this machine as a “reduced rotor operating speed aircraft,” or ROSA. That’s because with a traditional helicopter, the tips of the blades are spinning very quickly—at 60 percent the speed of sound or more. That produces a lot of noise. Jaunt’s CTO, Martin Peryea, says that the tips of the blades on their craft will spin at around 450 feet per second when the machine is hovering. That’s less than 40 percent the speed of sound, at sea level. At cruise, the main rotor is spinning even slower, meaning very little noise is coming from that part of the chopper. That’s an important consideration for a craft built meant to navigate around a densely populated city, but it comes at a cost.