Only the lazy does not write about the first ever launch of a SpaceX spacecraft on the ISS in recent days and what the consequences of this launch will be for the world and Russian cosmonautics. We did not write about this, but not because we are lazy, but because we did not particularly want to repeat the thoughts of many other authors on this issue. However, yesterday one of our subscribers asked a question that, it seems to us, was not widely covered.
During takeoff from Earth, astronauts experience overloads from 1g to 7g, which means that a person weighing 70 kg during takeoff is pressed against the chair with the same force as if his mass was 490 kg. In this case, overloads above 7g are usually an exception, and in the overwhelming majority of cases, overloads do not exceed 4g.
Moreover, high overloads during space launches are usually limited in time and last no more than a few minutes. So, when the Crew Dragon was launched, G-forces above 2g were in the third minute of flight, 40 seconds before the separation of the first stage, and also for about two minutes before the separation of the second stage.
The effect of overloads on the body is determined not only by their magnitude, but also by the rate of increase; in an unprepared person, after a few seconds, overloads of the order of 5g lead to loss of vision, impaired respiration, damage to body tissues and loss of consciousness, it was would be quite problematic.
However, astronauts are not ordinary people, they undergo a long training on a centrifuge and various simulators, as a result, they can maintain consciousness, coordination and sobriety of thinking much longer than other people, even with great overload.
In addition to this, their spacesuits are equipped with anti-overload systems that do not remove overloads, but reduce their impact on the body, by creating external pressure in the abdomen and legs, this counteracts the outflow of blood from the brain, which allows astronauts to remain conscious.
Another aspect of overload is the stiffness of movements due to the need to overcome a huge body weight, this problem is also solved through long training.
Personally, I have experienced large overloads on a sports plane and from personal experience I can say that at 3g even an unprepared person is quite capable of working with devices, at 6.5g it will be almost impossible to move, but a professional pilot at the same time quite calmly controls the plane, even without an anti-overload suit and specialized training of astronauts.