Hi everyone,
I am confused on a fundamental issue. I think that I am posting this question in the correct forum.
I just watched "Sixty Minutes," where JPL scientists were discussing the flight of the small helicopter launched from the surface of Mars. During the several interviews, the scientists and engineers focused much of the discussion on the difficulties of flying a helicopter in an atmosphere so much less dense than that found near the surface of Earth.
But I thought that lift emanated from the thrust produced by a helicopter's propellers.
As I understand the story, Robert Goddard was criticized for believing that a rocket could propel itself even in a vacuum. Goddard's critics incorrectly believed that a rocket required atmosphere against which the rocket's exhaust pushed. But Goddard correctly understood that the aft thrust itself produced the forward motion, in an application of Newton's Third Law of Motion.
So then why does the thinness of the Martian atmosphere affect the helicopter's flight? I am certainly not disputing JPL scientists -- not at all. I just want to understand what is going on.
To summarize my question, therefore, why is a rocket able to propel itself forward even in a vacuum, but the flight of a helicopter -- or a I guess an airplane for that matter -- depends upon atmosphere?
Thank you.
Stanley
I am confused on a fundamental issue. I think that I am posting this question in the correct forum.
I just watched "Sixty Minutes," where JPL scientists were discussing the flight of the small helicopter launched from the surface of Mars. During the several interviews, the scientists and engineers focused much of the discussion on the difficulties of flying a helicopter in an atmosphere so much less dense than that found near the surface of Earth.
But I thought that lift emanated from the thrust produced by a helicopter's propellers.
As I understand the story, Robert Goddard was criticized for believing that a rocket could propel itself even in a vacuum. Goddard's critics incorrectly believed that a rocket required atmosphere against which the rocket's exhaust pushed. But Goddard correctly understood that the aft thrust itself produced the forward motion, in an application of Newton's Third Law of Motion.
So then why does the thinness of the Martian atmosphere affect the helicopter's flight? I am certainly not disputing JPL scientists -- not at all. I just want to understand what is going on.
To summarize my question, therefore, why is a rocket able to propel itself forward even in a vacuum, but the flight of a helicopter -- or a I guess an airplane for that matter -- depends upon atmosphere?
Thank you.
Stanley