Orbital Re-Entry into Atmosphere

[Turtle]

Would the concept work on Mars if you reversed the blades of the helicopter so they were pulling the other way. Much like the way you change a fan setting? Would that not counter-act the effect of the vacuum? :)

 

First, Mars has a thin atmosphere, but it is not a vacuum. Propellers will work there and a helicopter with large rotors likely the same. Reversing the rotor direction would push the craft down to a crash, as that thrust is then added to the acceleration due to the gravity. :)

 

Here's that link again on a Mars airplane: >>

Page #5...The propeller is composed of two 60 [cm] diameter blades with a Goe795 profile. The calculated specifications of the

propeller, at high altitude on Earth for speed similitude with Mars, are listed in Table 4. ...

http://asl.epfl.ch/aslInternalWeb/ASL/publications/uploadedFiles/Sky-Sailor-Paper-Final.pdf

[TheBigDog]

Helicopters push the blades to create lift. When the engines fail they reverse the angle of attack of the blades to autogyro to the ground. As the craft falls it causes the blades to spin, and this causes the fall rate to slow. This was the principle employed by the company that wanted to use the rotary space craft to win the original x-prize. It ended up burning up do to rocketry issues, but the descending worked as they had hoped as I recall.

 

Rotary Rocket - Wikipedia, the free encyclopedia

 

Oops! Not x-prize, but a commercial venture.

 

Bill

[Moontanman]

Guys, yes Mars has an atmosphere, I didn't say it didn't but at 1% of Earths it would be considered a pretty good vacuum to us, not complete but better than most of us would be able make here on Earth without special equipment. Helicopters do not work at high altitudes on Earth, the power requirements are just too great, they would not work on Mars due to the "thin" atmosphere either. Yes a very light airplane with huge wings could fly on mars but a helicopter would not. The engineering of a helicopter that would work on Mars would be a challenge to say the least and almost certainly wouldn't be much of a help for a space craft trying to land.

[CraigD]

… the company that wanted to use the rotary space craft to win the original x-prize. It ended up burning up do to rocketry issues, but the descending worked as they had hoped as I recall.

 

Rotary Rocket - Wikipedia, the free encyclopedia

 

Oops! Not x-prize, but a commercial venture.

Back in the mid ‘90s, I was a big fan of Bevin McKinny’s “space helicopter” concept. I watched with sadness the slow retreat of its design from its most unusual elements, and the eventual financial failure of its attempted commercial development. Though I’m sure the McKinny has his share of disgruntled investors and former employees, my only gruntlement with him is that I don’t think he gave the appropriate historic nod to the Focke-Wulf Triebflügel, a 1944 design which strongly technically and superficially resembles the first drawings of what would eventually become the Roton.

 

That-which-would-become-the-Roton's early design emphasized very efficient aerodynamic lift-based performance at low altitudes, low empty and payload mass and mechanical simplicity via fuel delivery to rotor tip rocket motors by centrifugal force rather than mechanical pumps. The shrinking of the anticipated market for small payload launches forced a major change in design, eliminating the rotor tip motors and increasing payload and empty mass, then practical considerations forced the replacement of its centrifugally pressurized motors with conventional rocket motors, until ultimately it was just a peculiar single stage rocket with folding helicopter rotors in place of a parachute.

 

I’d like to see the original design more completely developed.