# Questions tagged [karman-line]

The Karman Line (named for Theodore von Kármán) represents a boundary between the Earth's atmosphere and space and is set by the FAI at 100km altitude. Use this tag to discuss the line and questions about its application.

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### Which was the first liquid non hypergolic engine to be reignited in space?

Which was the first liquid non hypergolic engine to be reignited in space? ( space = above 100km )
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1 vote
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### how to procure a Launch vehicle for injecting a cubesat into LEO at LOW COST?

Me and my team are working on sending Cubesats just beyond the Karmann line. For which we obviously need a launch vehicle and would like to procure one or if possible build one. If any aerospace ...
258 views

### Could you skim along the Karman line using a parafoil?

Imagine a person just wearing a spacesuit equipped with a parafoil returning from low orbit. Could they maintain altitude starting at 7.8 km/s above or along the Karman line slowly losing speed—maybe ...
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### Size of sugar rocket to reach space (suborbital)

How much propellant would an ideal single stage sugar rocket with dry mass of 1 kg need to reach the altitude of 100 km in a suborbital flight when launched straight up? Let us assume the specific ...
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### At what point does an object lose 50% of escape velocity?

I find the kalman line an unsatisfactory definition of space. Instead, I will use 50% of escape velocity. At what distance does this happen? If escape velocity is 11 km s and gravity is 9.81, I am ...
2k views

### Minimum velocity needed to cross Karman line

When we travel in a car upwards on a slope (against gravity), we can keep driving the car at a constant speed without accelerating (without changing its speed). Theoretically, the only thing we need ...
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### Would this idea of a water rocket to pass the Karman line work?

When I fly my water rockets as a hobby I use this formula to calculate the height of the flight so I get an idea of how high my water rocket will fly. My idea is to make a theoretical water rocket ...
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### How much delta V did the V2 have?

The V2 rocket was the first to cross the Karman line. To pass it you need at least 1.4 km\s. How much delta V did the V2 rocket have?
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### What would it take to bring VSS Unity over the Kármán line?

There's been a great deal debate about Virgin Galactic calling 50 miles "space", while most use a 100 km Kármán line definition for the term. VSS Unity has exceeded 89 km altitude on two ...
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### What permission do I need to build a rocket that goes to space? [closed]

I wanted to build a rocket that goes to the karman line at 340000 feet which is technically space. I know the rules and what I need to get to launch the rocket such as faa clearance and more but I ...
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### How can I calculate the weight a aero-spacecraft occupant experiences during sub-orbital but non-ballistic trajectories?

Once in orbit, astronauts experience "weightlessness" relative to their capsule or space station because they are moving at the same orbital velocity as the surrounding spacecraft. I have ...
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### Does NASA consider Joseph Walker to be an astronaut?

Joe Walker was a NACA and NASA test pilot who flew the X-15 aircraft twice above 100 km, which FAI uses their definition of an astronaut. Flight 90 achieved 106.01 km, and flight 91 reached 107.96 km....
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### Would the >100 km "knee" in Earth's atmosphere still be where MFP exceeded scale height if it were pure Ne or Ar?

There is currently one answer to How many solar system bodies have "knees" in their atmospheres? that points out that somewhere above roughly 100 km turbulent mixing drops off (thus the name ...
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### Are satellites whose orbits go below 100 km perigee considered having multiple spaceflights?

The International Aviation Federation (FAI) considers the space border at 100 km (330,000 ft) above sea level. So if an orbiting body goes below that altitude and continues its orbit without ...
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### Fastest rocket to reach space?

Spaceloft XL can reach space - 100 km - in 60 seconds So I wonder which rockets can reach that limit fastest Balloon-launched sounding rockets count but separately (from the moment they launch from ...
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### Why isn't the Kármán line itself considered to be in outer space?

The Kármán line is the altitude at which the atmospheric pressure is so thin a craft would need to achieve orbital velocity in order to maintain enough aerodynamic lift and control. Therefore, ...
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### When did the FAI adopt the 100km line as border to space (for their purposes)?

Let me preface this with a disclaimer: This is not a discussion about which height makes sense. This is purely about international recognition by the FAI. Wikipedia says "An international committee ...
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### With a 10% increase in Earth's mass, would the Karman line move up or down, and by how much?

This is an exercise to better understand the basic physics and math behind scale height and the Karman line. It was inspired by this answer to Why is FAI considering lowering the Karman Line to 80km? (...
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### Is there some fundamental limitation that would prevent steam-powered rockets from reaching space?

According to the Discovery Channel (see CNN article below) the latest attempt to use compressed steam propulsion to get to 5000 feet ended in tragedy. It's not yet clear the altitude it reached, ...
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### Which object has been to space the most times?

Which particular piece of hardware has crossed the Karman line most often? By hardware I mean anything other than organisms.
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### When is/will be the symposium to revisit the Karman line and consider the "McDowell line"?

In the January 16, 2019 Sixty Symbols video Where is the edge of space? Dr Meghan Gray from the University of Nottingham discusses Jonathan McDowell's paper The edge of space: Revisiting the Karman ...
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1 vote
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### What are the minimum and maximum calculated, published altitudes of the Kármán line?

I'd like to be able to say, "The Kármán line has been calculated to lie between ___ and ___ km." The "accepted" altitude of the ...
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### Temperature and Pressure Gradient across Kármán line

Has there been any experimental measurement of the temperature and pressure gradient across the Kármán line? How much time did it take for a space shuttle (such as Atlantis) to cross it, and whether ...
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### Could the $C_L$ of the X-15 be calculated from the flight data near the Kármán line altitude?

The "lift coefficient" $C_L$ can be very different for one specific aircraft at different speeds. According to this article from NASA about the lift coefficient: So it is completely incorrect to ...
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### Does an airplane in orbit near the Kármán line altitude, with the air providing lift, ever reach orbital velocity? [duplicate]

The equation for an airplane in orbit with the air providing lift would be: $$\frac{GM_Em}{(R+h)^2} - \frac{\rho(h) v^2 S C_L}{2} = \frac{mv^2}{R+h}$$ $GM_E$ is Earth's standard gravitational ...
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### Is the equation showed below the right one for an airplane flying at the Kármán line altitude?

$$\frac{GM_Em}{(R + h)^2} - \frac{ \rho v^2 S C_L}{2} = \frac{mv^2}{R + h}$$ $GM_E$ is Earth's standard gravitational parameter , $R$ is Earth's radius and $h$ the altitude of the airplane above the ...
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### What physical ways can the Kármán line be used? [closed]

I have also seen many posts on this. I understand what the line is used for legally. The Kármán plane or a plane that is most efficient at the line regardless of the shape seems not to have a specific ...
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### Does a credible Kármán plane reach escape velocity within 1 minute or does it follow the curvature of the Earth? [duplicate]

Edit: This question is no duplicate because here the dropping of the atmospheric density together with the horizontal line, play an important role. Furthermore none of the answers and question ...
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### Is a Kármán Rocket Possible? [duplicate]

Why are the rockets not razor sharp, skinnier and taper off at both ends farther to cut through air better? Would making a rocket more aerodynamic allow it to be more efficient flying as a "Kármán ...
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### Where does the definition of the Kármán line on Wikipedia come from?

According to Wikipedia's article about the Kármán line: The Kármán line is the altitude where the speed necessary to aerodynamically support the airplane's full weight equals orbital velocity ( ...
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### Is it correct to use the vis-viva equation when there are two forces acting on the orbiting body? [closed]

Edit: Although this question seems similar to the question "Is it correct to apply the vis-viva equation to an airplane that flies in a straight line", it is different because there the airplane flies ...
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### Is it correct to apply the vis-viva equation to an airplane that flies in a straight line at the Kármán line?

The vis-viva equation models the motion of an orbiting body and it applies when the only force acting on the body is it's own weight. So is it correct to apply this equation to an airplane that ...
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### Why is FAI considering lowering the Karman Line to 80km?

I ran across this FAI statement The Karman line is the 100km altitude used by FAI and many other organisations to mark the “boundary” of space . In the last few years there have been many scientific ...
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### What's the *calculation* for the altitude near the Kármán line where the lifting force equals the centrifugal force? [duplicate]

Edit: This question is not a duplicate of the associated question and has no answers to it that were posted for that associated question. This question asks specifically for a calculation, the ...
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### Are there calculations regarding the Kármán line in the Theodore von Kármán collection?

According to this article, page 673: The "von Kármán line" appears to be what mathematicians refer to as a "folk theorem" , arising out of a conference discussion but never formally published by ...
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### What is the practical use of the Karman line?

There have been several questions recently about the details of the definition of the Karman Line and the history of those calculations. This is not about those issues. The question is: In practical,...
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### At what conference did the "von Kármán line" arise, and was discussed for the first time?

From this article on page 673: The "von Kármán line" appears to be what mathematicians refer to as a "folk theorem", arising out of a conference discussion but never formally published by him. It ...
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### Is the definition of the Kármán line from Wikipedia right? [closed]

Edit: this question is about making clear that the Wikipedia's article about the Kármán line is an interpretation, not the definition ! Why not consider the Kármán line as a curved boundary that ...
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### What did Karman's original "Karman line" calculations look like?

Looking for the atmospheric parameters (density for example) and vehicle parameters (CL for example) as well as formulae that were used in the original calculation. Primary sources strongly preferred,...
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### Did the Soviet Union put an unmanned satellite in "very low orbit"above the Kármán line which used aerodynamic attitude control?

This interesting, archived page https://www.webcitation.org/618QHms8h?url=http://www.fai.org/astronautics/100km.asp which I found in this answer, says: Later in the same decade (or very early in ...
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### How did the X-15 control attitude above the Kármán line?

This interesting, archived page https://www.webcitation.org/618QHms8h?url=http://www.fai.org/astronautics/100km.asp which I found in this answer to What would a "Kármán plane" look like, a ...
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### what is the relevance of ion cyclotron and ion collision frequency ratio

On earth, the ion cyclotron and ion collision frequency ratio is 1 at roughly 118 km, and this is used as one of the definitions of the limit to space. What are ion cyclotron frequency and ion ...
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### Where does space begin on planets without atmospheres?

On Earth the Karman Line is used as the boundary of space, and I believe it is defined as the height where you would have to go faster than orbital speed in order to obtain aerodynamic lift. Therefore ...
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