0
$\begingroup$

The Karman line is the altitude at that the airspeed required to generate the sufficient lift to support itself exceeds the orbital speed. Looks like the Karman line is defined as some fixed value, equal to 100 Km. How this could possibly be?

In a usual flight, "the airspeed required to support itself" depends dramatically on the wing and can vary I think from 29 km/h for Gossamer Albatross till 389 km/h for X-15.

$\endgroup$
3
$\begingroup$

The calculation definitely does depend on wing loading. However, the Kármán line does not, because it is not actually defined by that calculation, it is defined by statement. The calculation, for a “typical” airplane, is just motivation for the value.

$\endgroup$
1
$\begingroup$

From the Wikipedia article:

Although the calculated altitude was not exactly 100 km, Kármán proposed that 100 km be the designated boundary to space, because the round number is more memorable, and the calculated altitude varies minutely as certain parameters are varied.

(emphasis mine)

$\endgroup$
  • $\begingroup$ The difference is not 300 km/h, the difference is 13×, and stays so as the density decreases, because the density is multiplicative factor (true airspeed increases inversely with density; update: I first said stall speed, but since this is supersonic, the flow is never attached in the first place). $\endgroup$ – Jan Hudec Jun 8 '18 at 11:10

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.