The North American X-15 was aimed at breaking airspeed and altitude records. The flights that sought to achieve new airspeed records (Mach 5+) were rather leveled but the flights into the upper stratosphere, into the mesosphere and into space were parabolae. Since all of them were parabolic flights, was the pilot always weightless at peak altitude even during the flights that didn't surpass the 50 mi space border? In the stratosphere I think it depended on the rotational velocity of the plane whether they experienced weightlessness, negative gravity or "just" lower positive gravity after engine shutdown.

The same question also applies to any other high atmosphere parabola-flying plane such as Aleksandr Fedotov's MiG-25 reaching 37,650 metres (123,520 ft), Iven Kincheloe's Bell X-2 reaching 38,491 m (126,283 ft) and the SpaceShipOne and Two reaching sub-space altitudes.


1 Answer 1


Yes they did. Take away both rocket thrust and wing lift, and the plane goes into free fall. In this condition everything on board becomes weightless.

The pilot would feel only the light bursts of thrust from the small manoeuvring rockets, and the slow return of aerodynamic lift during re-entry.

You don't even need to go into outer space; check out the vomit comets used to train astronauts.


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