Helicopter performance (split from Get ready for the landing of Perseverance !)

[Airbrush]

This Mars-chopper is about 4 lbs in weight on Earth.  How much bigger and more capable could a helicopter be on Mars?  How long could the flight time be?

[swansont]

Here's a quick writeup of the performance of the Mars helicopter

https://www.wired.com/story/the-physics-of-nasas-new-mars-helicopter/

and a more general treatment of helicopter (in the context of a human-powered device)

https://www.wired.com/2012/06/how-hard-is-the-human-powered-helicopter/

 

You can see the thrust depends on Av^2, where A is the rotor area and v is the speed of the air you push down. So you can get more thrust by increasing the area of your blades or having them move faster, but the first adds to the weight and the second requires more power - so you either need bigger batteries, which adds weight, or you reduce the flight time.

[Airbrush]

On 4/21/2021 at 3:47 AM, swansont said:

...You can see the thrust depends on Av^2, where A is the rotor area and v is the speed of the air you push down. So you can get more thrust by increasing the area of your blades or having them move faster, but the first adds to the weight and the second requires more power - so you either need bigger batteries, which adds weight, or you reduce the flight time.

Thanks for the info.  What is the weight limit for a Mars copter?  Is there a weight/power/flight-time analysis for this?  It must depend on weight and length of flight.  A few minutes would be enough flight time for scouting.  At some size of batteries, flight becomes impossible.  Maybe have a giant mechanical sling shot that throws a glider with big wings into the air. It could glide with the help of a propeller, and carry more weight in cameras and sensors, maybe longer than a helicopter could hover?

Edited April 23, 2021 by Airbrush