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# How does the plasma blackout work?

## Question

TL;DR: Is there any kind of formula which allows to calculate whether I'll have a plasma blackout on a given altitude (or atmospheric pressure) and speed?

Hey folks,

I'm planning a scientific mission to Laythe to gather as much data as possible (so I plan to visit all biomes with one vehicle). Given that Laythe has an oxygen-rich atmosphere, I don't want to wait multiple hours to travel through half a planet, and I will probably have to land on small spots of hilly terrain as well as in see, the obvious choice is to build a hypersonic plane with vertical takeoff and landing with a tiny mining rig onboard. Unmanned, for the sake of realism. Flying with J-X4 Whiplash on 4 Machs and 25-30 km altitude looks good.

The problem is that sometimes my plane encounters plasma blackout, with consequent loss of control. I try preventing that by flying higher and slower. How can I check that I'm safe on a given altitude and speed? I tried experimenting, and the results look inconclusive: I experience blackout at 830 m/s, but a couple minutes later I fly normally at 1350 m/s, at a lower altitude.

Edited by alexeykuzmin0

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```commNetQTimesVelForBlackoutMin = 500 // Minimum dynamic pressure * velocity for comms to start blacking out from plasma (if that option is enabled)
commNetQTimesVelForBlackoutMax = 2500 // Maximum dynamic pressure * velocity for comms to start blacking out from plasma (if that option is enabled)
commNetTempForBlackout = 1100 // Minimum shock temperature for comms to start blacking out from plasma (if that option is enabled)
commNetDensityForBlackout = 5.0000000000000002E-05 // Minimum density for comms to start blacking out from plasma (if that option is enabled)
commNetDotForBlackoutMin = -0.86599999999999999 // Minimum dot between velocity and link direction for comms to start blacking out from plasma (if that option is enabled)
commNetDotForBlackoutMax = -0.5 // Dot between velocity and link direction for full blackout multiplier
commNetBlackoutThreshold = 0.5 // Threshold blackout value below which comms are entirely blacked out (if that option is enabled). Value calculated as 1 - inverse lerp of QTimesVel * inverse lerp of dot```

So, it depends on the dynamic pressure and temperature, honestly no clue what the "dot" is meant to be.

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Never looked into it myself, but perhaps the Thermal Data GUI in the cheats/physics tab will tell you?

If one of the external air temperature numbers goes over some threshold, then a plasma gets generated. But it would certainly be altitude dependent also.

I think you're going to need to make some plots of temperature vs. altitude. Or speed vs. altitude. I don't think it's going to be a simple relationship.

Edited by bewing
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29 minutes ago, 4x4cheesecake said:

honestly no clue what the "dot" is meant to be.

Vector dot product. It's like a multiplication, with the cosine of the angle calculated in too.

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So, AFAIU, I'm safe below 1100 K and if the angle between my velocity and link direction is less than 45 deg.

Great, thanks!

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On 3/11/2019 at 9:54 AM, 4x4cheesecake said:

```commNetQTimesVelForBlackoutMin = 500 // Minimum dynamic pressure * velocity for comms to start blacking out from plasma (if that option is enabled)
commNetQTimesVelForBlackoutMax = 2500 // Maximum dynamic pressure * velocity for comms to start blacking out from plasma (if that option is enabled)
commNetTempForBlackout = 1100 // Minimum shock temperature for comms to start blacking out from plasma (if that option is enabled)
commNetDensityForBlackout = 5.0000000000000002E-05 // Minimum density for comms to start blacking out from plasma (if that option is enabled)
commNetDotForBlackoutMin = -0.86599999999999999 // Minimum dot between velocity and link direction for comms to start blacking out from plasma (if that option is enabled)
commNetDotForBlackoutMax = -0.5 // Dot between velocity and link direction for full blackout multiplier
commNetBlackoutThreshold = 0.5 // Threshold blackout value below which comms are entirely blacked out (if that option is enabled). Value calculated as 1 - inverse lerp of QTimesVel * inverse lerp of dot```

So, it depends on the dynamic pressure and temperature, honestly no clue what the "dot" is meant to be.

The "dot" might be the dot product, or vector projection of velocity direction and link projection. This makes sense if they are talking about direction and those two quantities would no doubt be vectors.

Edit: Sorry for duplicate response, didn't see earlier similar response.

Edited by r3_141592654

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