# Is the stall speed different at -1G?

This question makes me wonder what happens at -1G.

When the load factor of an aircraft increases above 1, the stall speed increases. As the load factor comes closer to 0, stall speed decreases and becomes "infinitely" low (basically 0 kts) as an aircraft can not stall at 0G. But what happens at a negative load factor?

For example, during inverted flight the airfoil is still producing lift when the angle of attack is negative (enough). Thus the stall speed should change and as the efficiency of a inverted wing is (almost definitely) not as high, I am assuming that the stall speed decreases.

But is a negative G maneuver necessarily to be done in inverted flight? No!

As a glider pilot, I can refer to negative Gs during winch launches, or rather when they fail. You often practice cable fails, where your instructor disconnects you from the winch. To maintain speed and prevent a stall you push the nose down, ideally flying a small Zero-G parabola (as this will prevent a stall). But what if you push even more? Where is the stall speed going to be at?

• It is more correct to reference stall angle of attack than stall airspeed. A given airfoil can technically stall at any airspeed once AoA increases beyond the critical AoA. – Rhino Driver Aug 23 '15 at 19:38
• AoA changes with the load factor as well. In fact, I believe AoA will instantaneously change with load factor. – Rhino Driver Aug 23 '15 at 23:43
• In your question you said : >When the load factor of an aircraft increases above 1, the stall speed decreases. Well this is not true, saying that means that for example your stall speed in a 60 degrees turn will be less than the stall speed in straight and level flight. So it is obvious to say that when the load factor of an aircraft increases above 1, the stall speed increases – Thomas May 22 '16 at 17:53
• I would correct some words in the first paragraph : When the load factor of an aircraft increases above 1, the stall speed increases. As the load factor comes closer to 0, stall speed decreases and becomes infinitely low as an aircraft can not stall at 0G. – Thomas May 22 '16 at 18:32
• Yes, first two sentences are now correct after recent edit to fix another edit; stall speed increases as load factor increases, and is 0 at 0G. – quiet flyer Nov 4 '20 at 13:03