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4 Answers

G Loading

Asked by: 6432 views Aerodynamics

Why do most airplanes have a higher positive G load limit verses a lower negative G load limit? Said another way: Why are negative G loads more restrictive? Thanks for the feedback.

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4 Answers



  1. Mark Kolber on Aug 03, 2015

    Just because there are almost no normal flight conditions that result in substantial negative Gs. I think even in aerobatic maneuvers, positive Gs fighting the pull of gravity far outweigh negative Gs into the pull of gravity.

    Why add to the structure and weight of an aircraft, reducing its useful load (never mind increasing its cost!) when it’s not needed?

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  2. Brian on Aug 05, 2015

    In acro it depends on the class. The unlimited class typically uses aircraft capable of +\- 10g. That said the human body can fight blackout by tightening body muscles where as we cannot fight red out. So the body simply doesn’t do as well with negative as it can with positive.

    Although it has nothing to do with the fight of gravity being any different where inverted or upright. An idebtical inside (upright) and outside (inverted) loop will see the same g load albeit one being negative.

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  3. jmt on Aug 05, 2015

    maintaining a positive G load when flying aerobatics helps with maintaining airspeeds and profiles throughout the maneuver…for example in a T-6 Texan II doing a loop, entering at 200kts a 4G pull will put you on top at a safe speed (without adding power) and without going into negative Gs (which make it harder to control the plane and can be rough on an oil system). That same 4G pull also gives you identical, mirroring gain and loss of altitude…so lets say you enter at 200kts at 6000′, the top should be 9000′ and you should come back out at 6000’….the 4G pull helps make all that happen.
    Outside of aerobatics negative Gs are harder for the body to handle, aerodynamically more difficult to control and can cause issues with engine systems if held for more than a few seconds…same with upside down flight.

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  4. Dan Chitty on Aug 05, 2015

    Thanks for the feedback.

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