Where's the Karman Line for Kerbin?

[MAFman]

I know that the atmosphere "ends" at exactly 70 km on Kerbin, but I'm wondering where the Karman line is, where a hypothetical plane would have to fly at orbital speed for the lift its wings could generate to equal its weight equals the centrifugal force it feels from moving so fast horizontally.

[Nuke]

planets tend to be a lot fluffier than those simulated in ksp. if humans found that the atmosphere just stopped at 70km, that would be the line we use. in reality we use a more convoluted system because we have fluffy planets. 

[Meecrob]

I'm not sure we can fly a vehicle that uses an airfoil for lift at the Karman Line on Earth. The (paraphrased) definition of the "Karman Line" is "the altitude at which the atmospheric pressure is assumed to be zero." Given that definition, Kerbin's Karman Line is 70km.

(https://howthingsfly.si.edu/ask-an-explainer/what-altitude-does-atmospheric-pressure-become-zero)

Also, if an object is flying at orbital speed, by definition, it does not require aerodynamic lift, since it is just falling around the planet. Objects require lift (or some other force like one provided by a a rocket engine) to maintain altitude when operating at less than orbital velocity.

 

 

Edited February 24, 2023 by Meecrob

[MAFman]

20 hours ago, Nuke said:

fluffy planets.

That's a hilariously good way to describe the atmosphere 

[StrandedonEarth]

20 hours ago, Meecrob said:

I'm not sure we can fly a vehicle that uses an airfoil for lift at the Karman Line on Earth. The (paraphrased) definition of the "Karman Line" is "the altitude at which the atmospheric pressure is assumed to be zero." Given that definition, Kerbin's Karman Line is 70km.

(https://howthingsfly.si.edu/ask-an-explainer/what-altitude-does-atmospheric-pressure-become-zero)

Also, if an object is flying at orbital speed, by definition, it does not require aerodynamic lift, since it is just falling around the planet. Objects require lift (or some other force like one provided by a a rocket engine) to maintain altitude when operating at less than orbital velocity.

 

 

My understanding of the Karman line is that it’s the altitude where the velocity required to generate enough aerodynamic lift for level flight is equal to the orbital velocity at that altitude. This varies somewhat as the atmosphere expands and contracts.  But drag is still significant. 

[Gargamel]

Moved to KSP discussion