Videos of reentries?

[nothke]

I was wondering how the reentries look in real life, and I found out that videos of reentries are so obscure. Also, there are no external shots except those one stretched pixel from ground tracking cameras (well duh, they don't have 3rd person!). Yeah, but I can't even find aero tunnel tests. And the cockpit views are rare, are crew members really busy then or what?? The only thing I found so far are one of Shuttle with a really poor quality, and one of Gemini:

starts at 3:20:

I actually didn't know that they are so "flashy" and actually.. dark. I more imagined it as a constant glow

PS: by "reentry" I mean the atmospheric burn sequence

Edited May 10, 2013 by nothke

[Kryten]

Can't link it myself right now, but Google 'reentry Hayabusa'.

[NovaSilisko]

Here's a gif of it

Larger more explodey object is the main spacecraft bus, the sample capsule is at the bottom right, and not disintegrating.

[Tommygun]

Have you try searching YouTube under "Soyuz Re-entry" ?

[nothke]

Thanks, I've actually seen Hayabusa some time ago.. Yes, these are "one stretched pixel" shots I mentioned. The best one of Shuttle I found so far:

I was thinking more of how does it look in close up. In artist renderings there are 2 different "looks". There either are flames coming of sides of the capsule paralelly (similar to how the shaders look now in KSP) like HERE or HERE

and the other one where the capsule "pushes" a sphere of hot gas like HERE or HERE

I guess it depends on the shape/type of material used. But which one should be more realistic? I guess those OFFICIAL artist renderings tend to be as accurate as possible so should we trust them? =)

Edited May 10, 2013 by nothke

[Kryten]

I know HTV once re-entered with a recoverable capsule inside to record the breakup; if you can find the footage of that, it should be a lot more impressive than the 'stretched pixel' ones.

EDIT: It was HTV-3.

Edited May 10, 2013 by Kryten

[K^2]

I was thinking more of how does it look in close up.

I wouldn't know how to film that even if that was the specific goal. There is no way to actually get up close, and tracking something going that fast from that far away with a telescope? Sounds very tricky.

Theoretically, I would expect most of the glow coming from ship itself, plus additional glow coming from atmosphere where it becomes ionized. The later is most likely to happen in the shock wave, so it should be a bit closer to the second set of images you link, but not quite right on any of them.

[nothke]

I wouldn't know how to film that even if that was the specific goal. There is no way to actually get up close, and tracking something going that fast from that far away with a telescope? Sounds very tricky.

You COULD get a close up in wind tunnels

[nothke]

Hmm there seams to be no parallel flames on orion

[K^2]

You COULD get a close up in wind tunnels

A mach 15+ wind tunnel?

[nothke]

A mach 15+ wind tunnel?

http://en.wikipedia.org/wiki/Expansion_tunnel#LENS-X

30 mach

[Tommygun]

http://en.wikipedia.org/wiki/Expansion_tunnel#LENS-X

30 mach

Holey Cow, I didn't know they had a wind tunnel that fast.

They mentioned rupturing diaphragms, I wonder if it's only good for a few seconds?

[Brotoro]

Thanks, I've actually seen Hayabusa some time ago.. Yes, these are "one stretched pixel" shots I mentioned. The best one of Shuttle I found so far:

I was thinking more of how does it look in close up. In artist renderings there are 2 different "looks". There either are flames coming of sides of the capsule paralelly (similar to how the shaders look now in KSP) like HERE or HERE

and the other one where the capsule "pushes" a sphere of hot gas like HERE or HERE

I guess it depends on the shape/type of material used. But which one should be more realistic? I guess those OFFICIAL artist renderings tend to be as accurate as possible so should we trust them? =)

I watched a Space Shuttle reentry as it passed over northern New Mexico. The sky was already light (it was close to sunrise), so I didn't see so much of the glow, but instead saw the persistent "smoke trail" it left behind (that took many minutes too dissipate). You can see sort of what it looked like in that shuttle video posted earlier when he zooms in on the trail behind the shuttle and you see the billowing cloud-like effect. I'm not sure what exactly causes that cloud since the shuttle does not use an ablative heat shield, so it shouldn't be leaving behind a lot of material.

And several minutes later I heard the sonic boom from the passing.

[nothke]

..but instead saw the persistent "smoke trail" it left behind (that took many minutes too dissipate). You can see sort of what it looked like in that shuttle video posted earlier when he zooms in on the trail behind the shuttle and you see the billowing cloud-like effect. I'm not sure what exactly causes that cloud since the shuttle does not use an ablative heat shield, so it shouldn't be leaving behind a lot of material.

I guess it's a water vapor contrail, just like the ones made by wingtip vortices. But I am not sure where that amount of water might come from. It's gotta be a byproduct of that super heated plasma gas in front of the shuttle, but I am perplexed what exactly is it.

[Kryten]

Could be oxides of nitrogen, it's certainly hot enough at the leading edge to produce them.

[nothke]

Actually, after doing some googling, the "smoke" is actually plasma itself!

"A shockwave forms just in front of the nose and underside of the spacecraft. Between this shock and the vehicle itself temperatures may reach 10,000 to 12,000 Kelvin. (The heat resistant surfaces of the shuttle only reach a maximum of 1600 K themselves.) This very high temperature ionises the gas close to the shuttle forming a plasma cloud or miniature ionosphere around the spacecraft. The plasma frequency (that frequency below which radio communications is not possible) may rise to many gigahertz around the lower parts of the vehicle. This gives rise to a communication blackout for direct communications between the Shuttle and ground control. This typically lasts from 25 to 12 minutes prior touchdown, a total outage of 12 to 13 minutes."

if you google "plasma trail", you will only see Shuttles xD

[Brotoro]

The trail I saw that lasted several minutes was not a bright glowing trail (that effect immediately behind the shuttle faded rapidly)... The trail looked like dark billowing smoke. I don't understand how ionized gas could last so long without cooling (the text above referring to the ionization lasting 20 minutes refers to the effect that surrounds the shuttle, not how long it lasts at a spot after the shuttle passes) or why it would appear dark.

[K^2]

Holey Cow, I didn't know they had a wind tunnel that fast.

They mentioned rupturing diaphragms, I wonder if it's only good for a few seconds?

Yes. It only gives a short burst of air at these speeds. No idea how long exactly, though.

[softweir]

The trail I saw that lasted several minutes was not a bright glowing trail (that effect immediately behind the shuttle faded rapidly)... The trail looked like dark billowing smoke. I don't understand how ionized gas could last so long without cooling (the text above referring to the ionization lasting 20 minutes refers to the effect that surrounds the shuttle, not how long it lasts at a spot after the shuttle passes) or why it would appear dark.

Yes, the brown smoke would be nitrogen oxides - any time air is heated and compressed enough, some nitrogen will react with oxygen. Lightning can generate large masses of the stuff!

Yes. It only gives a short burst of air at these speeds. No idea how long exactly, though.

I saw one demonstrated on TV. They have two cylinders - one is a gas-cannon which fires a piston along it, towards a diaphragm at the far end. The piston compresses gas trapped between it and the diaphragm. When the pressure gets high enough it bursts the diaphragm, sending a pulse of ultra-sonic gas down the second cylinder. So it can hardly be called a "wind-tunnel" - more a "hyper-sonic pulse tunnel"!