Creating that helicopter must have been a very interesting and difficult challenge. Lift L for rotor blades is calculated by the equation L = ½ ρ(v^2)ACL, where ρ is atmospheric density. v is the speed of the blades moving through the air (roughly speaking). A is the total blade area. And CL is the coefficient of lift, which is determined by the angle of the helicopter, if I understand it right.<p>Mars' atmospheric density at surface averages .087 psi, roughly .06% of Earth's average (14.69 psi). (source: <a href="https://en.wikipedia.org/wiki/Atmosphere_of_Mars" rel="nofollow">https://en.wikipedia.org/wiki/Atmosphere_of_Mars</a> )<p>That means right off the bat you're going to need to increase the speed of the blades squared times the total area of the blades (i.e., (v^2)A) by a factor of ~1666.66 just to get the same lift on Mars that you would on earth.
JPL published a video about the idea three years ago: <a href="https://www.youtube.com/watch?v=vpBsFzjyRO8" rel="nofollow">https://www.youtube.com/watch?v=vpBsFzjyRO8</a>