Plasma effects during rocket launches

[Streetwind]

During a discussion of how KSP shows reentry effects on rockets during launch, if they are going fast enough, someone said that this happens with IRL launch vehicles too. Which surprised me, considering I've been watching rocket launch broadcasts and recordings for the past five years, and never saw it happen. And the only relevant search hits Google allows into my personal filter bubble are from KSP forums and reddit discussing the ingame effects.

So, dear science forum: does this actually do happen IRL, and if so, where can I find video footage? I'm quite curious about this

[Steel]

It would happen, but IRL rockets are never going fast enough before they get out of the thicker atmosphere. It happens in KSP because orbital velocity is so low and re-entry effects are scaled accordingly

[sevenperforce]

24 minutes ago, Steel said:

It would happen, but IRL rockets are never going fast enough before they get out of the thicker atmosphere. It happens in KSP because orbital velocity is so low and re-entry effects are scaled accordingly

Well, it could happen, but that's part of why IRL rockets don't do the full gravity turn too soon, preferring instead to climb above the majority of the atmosphere. 

[Streetwind]

I know it's common for a lot of launchers to go rather steep, and then flatten out at or above 120km.

But I'm asking if there are launchers that don't do this, and particularly, if those launchers do gain a mild plasma sheath for a while. And if someone's ever managed to get it on video.

[QuesoExplosivo]

This:

http://www.astronautix.com/s/sprintabm.html

"Phased-array radars and high-speed computer processing allowed the warhead to be tracked, steering commands for the Sprint to be calculated, and uplinked to the missile via a radio connection of the frequency and power to be received through the ionized missile exhaust and plasma sheath surrounding the missile."

Edited July 24, 2016 by QuesoExplosivo

[Silavite]

Video of the said missile.

You can see the atmospheric heating starting at 0:24.

[p1t1o]

Ah, the Sprint, one of my favorites.

And one of my favorite anecdotes to go with it:

(Quoted from "ABM Research & Development at Bell Laboratories"  http://www.alternatewars.com/WW3/WW3_Documents/ABM_Bell/ABM_Bell.pdf)

"The SPRINT missile, with its acceleration to
high velocity within the dense atmosphere at low
altitudes, produced such high aerodynamic heating
that its skin surface could be cooled with an
oxy-acetelyne torch!"

 

That PDF makes some excellent reading btw!

[magnemoe]

On 22.7.2016 at 4:09 PM, sevenperforce said:

Well, it could happen, but that's part of why IRL rockets don't do the full gravity turn too soon, preferring instead to climb above the majority of the atmosphere. 

Yes, low orbit on Earth is around 400 km, on Kerbin its 100 so on kerbin you have to do an far faster gravity turn, you also don't get plasma effects on earth with 1 km/s at 30 km, its SR71 environment. 

[Streetwind]

1 hour ago, magnemoe said:

Yes, low orbit on Earth is around 400 km, on Kerbin its 100 so on kerbin you have to do an far faster gravity turn, you also don't get plasma effects on earth with 1 km/s at 30 km, its SR71 environment. 

it's not just a slower turn due to a higher target altitude. A lot of rockets actually do things we teach KSP players to avoid - fly relatively steep until past the Karman line, then flatten out relatively abruptly. Upper stages also fly for long periods of time at a radial-out angle to maintain altitude instead of heading prograde while carrying upwards momentum out of a gravity turn.

Here's an example from an Ariane 5 launch. Note that by the time the spacecraft gains altitude again at 4,000 km downrange, it is already well into its GTO insertion burn, with an apoapsis climbing rapidly away from the Earth. Now, the Ariane 5 is a particularly drastic example, but plenty of other launch vehicles also do this in some form or another - including the Atlas V and the Falcon 9, to name some US ones.

Edited July 25, 2016 by Streetwind

[magnemoe]

20 minutes ago, Streetwind said:

it's not just a slower turn due to a higher target altitude. A lot of rockets actually do things we teach KSP players to avoid - fly relatively steep until past the Karman line, then flatten out relatively abruptly. Upper stages also fly for long periods of time at a radial-out angle to maintain altitude instead of heading prograde while carrying upwards momentum out of a gravity turn.

Here's an example from an Ariane 5 launch. Note that by the time the spacecraft gains altitude again at 4,000 km downrange, it is already well into its GTO insertion burn, with an apoapsis climbing rapidly away from the Earth. Now, the Ariane 5 is a particularly drastic example, but plenty of other launch vehicles also do this in some form or another - including the Atlas V and the Falcon 9, to name some US ones.

That was an far slower turn than I imagined, more like my standardbase launches, the base is far less aerodynamic than an barn so its important to get out of the thick part of atmosphere first, it also uses an radial out burn on base itself who is upper stage with 1500 m/s dV but only 0.5 twr so I need to push Ap forward while gaining speed and climbing. 

Falcon 9 does an slow turn to reduce the horizontal distance traveled to make it easier to get back to pad.  

 

[wumpus]

There was a bit in Ignition where one fuel "created too much plasma" that would interfere with missile guidance (note that most of the fuels in Ignition are military in nature as HLOX and KLOX are pretty obvious.  Getting ones that can sit on the missile-rail on a ship exposed to all weather* is another story).  While I suspect that there is a certain amount of plasma, some fuels create more.

It is a bigger effect coming down.  I'm pretty sure Columbia was lost during the "can't communicate due to plasma" time coming down.

* not sure this is the case, but it still has to be ready (i.e. already gassed up) and ready to go on the rail and stay there until the fire command is given.

[ZooNamedGames]

Well even if we could (which we can), it's a generally poor idea to do so. As someone mentioned above, rockets tend to do a very very large curve where it's a mostly steep vertical climb. By the time you are starting to build horizontal momentum (where is where most of your velocity is going) your far above the majority of the atmosphere and don't get those effects. Not to mention, it's additional weight and engineering to create rockets that can withstand the heating. So to avoid having to add extreme heat resistance materials on rockets, they just have them go abit higher.

In KSP, as someone again mentioned, this is due to the small size of Kerbin and how reentry speeds are close to orbital speeds. If you want to see how reentry would look and behave, try downloading RSS, and as a suggestion, RO to complete said experience.