# Might Ingenuity tip over?

While Ingenuity patiently waits for its preflight checks to pass, how likely is it that a wind gust could tip it over? How strong and how rare a gust? Those rotors have plenty of area. (Surely NASA considered this scenario.)

For simplicity let's say that prior gusts have already scooted it until its downwind feet have caught on a lip of rock, so now it can't scoot any farther but will now tip instead.

Bonus: could it push itself back upright into a pose from which it could launch and fly, maybe by whacking its rotors against the ground?

• i think the "rotor whacking thing" might just damage the rotors Commented Apr 11, 2021 at 12:40
• Very unlikely as the ground pressure on Mars is less than 1% of that on Earth. The only reason it can itself take off is due to the rotors very high speed. Commented Apr 11, 2021 at 16:12
• I would love if someone answered this with math(s). Blades are 1.2m across, it's about 50cm high. Commented Apr 14, 2021 at 21:37

## 3 Answers

The wind on Mars simply isn't that powerful. For comparison, the blades, which are rather large, are moving at the tips around 0.7 mach. It would take wind speeds on that order to cause it to have any measureable effects, and the winds aren't anywhere near that strong on Mars.

• Informal sources say 60 mph has been recorded directly; 80 mph is needed to move sand patches; big dunes exist. Similarly sized terrestrial helis (0.8 m rotor) have tip speed 150 m/s = 0.4 mach, and even with wide "training gear" skids and lower CG, they tip over in winds much slower than that. Commented Apr 9, 2021 at 16:59
• The atmosphere is only 1% that of Earth, meaning an 80mph gust on Mars has about the same power as a 0.8mph gust on Earth. Commented Apr 9, 2021 at 18:08
• @JörgWMittag indeed! Could you feel the wind on Mars?
– uhoh
Commented Apr 9, 2021 at 19:35

At last, on 2021 May 10, an answer from the designers.

Thanks to the thin atmosphere (1% of Earth’s), wide landing gear stance (45° tip-over angle), and low center of gravity (40% of the mass is in the fuselage), the parked helicopter can easily withstand winds in excess of 135 mph, far beyond what we expect to encounter.

... Our strategy for landing in windy conditions is to come down with authority—placing Ingenuity’s feet firmly on the ground so that it won’t drift across the surface of Mars and snag a foot on a rock.

So "scooting" is unlikely, and while parked a strong enough gust is vanishingly unlikely.

• "Come down with authority" So here we have a specific reference to design intent for enduring intentional sort-of-hard landings without bounce or rebound... hence the damping knees discussed in other thread. Sometimes Ingenuity needs to really stick the landing! Commented Apr 8, 2022 at 21:03

Firstly, tipping won't be possible because of Mars' low wind speeds

• It would take wind moving at around 0.7 mach to see any interesting results
• Ingenuity's long leg span must also be considered and its wide stance

There is also a third factor that comes into play.....

• The heavy batteries at the base give it a low center of gravity

( yes the gravity on mars is less so the batteries wouldn't weigh much, but some weight is better than none!)

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I don't think it would ever scoot over to a rock and then tip over because of the weight of the battery pack

• The (Martian) gravitational force on the battery, the length and angle of the leg, and good old mgh, would reveal how much energy a gust has to impart to lift the battery past "top dead center." Commented Apr 11, 2021 at 22:03