Fix for shock heating on assent yet?

[Freshmeat]

Research to support @ExtremeSquared from @Norcalplanner. I always get lots of flames when I launch, and sometimes overheat gauges showing. Yet my ascents are mostly pretty economic, at 3200-3300 m/s.

[Streetwind]

@Superluminaut If you want an actual solution you can implement, I can tell you how to edit physics.cfg to make it happen.

However! Changing those values changes the way KSP displays atmospheric effects in general. You can shift the point at which white effects transition into red effects to a higher speed, so during launch, you at least don't see flames; but in return, that means that a reentering capsule will stop showing flames while still going faster and being higher up than normal. Similarly, you can tweak the fudge factor for atmospheric effects that forces flames to appear at the low speeds of the stock game, so that you need to go faster to see effects at all. But then a reentering capsule will show less effects as well.

Another thing you could do would be to install a mod like Sigma Dimensions and use it to make your atmosphere smaller. Real life rockets don't show flames during ascent because 90% of their acceleration happens outside the atmosphere. which is extremely thin relative to the size of the Earth. Kerbin's atmosphere is way too thick by comparison, hence the reason why KSP rockets spend most of their time accelerating inside the atmosphere and provoking reentry effects. If you make the atmosphere of Kerbin some 20-30 km thick instead of 70 km, then you'll reliably stop seeing atmospheric effects during ascent. Of course, the downside is that reentry becomes a much more dangerous and harsh proposition, much like it is in real life. Also, planes won't be able to fly nearly as high.

(EDIT: You could also make your planets larger instead of making the atmospheres smaller. But that, of course, changes the entire game drastically.)

Those are the only implementable solutions you have. You cannot selectively avoid atmospheric effects based on arbitrary personal opinions like "but this is a launch". Physics doesn't work that way. If you go at speed X through air at density Y, you get flames; it doesn't matter if you're going up or down. If neither solution appeals to you, then I'm sorry to say, you're out of luck.

Edited June 13, 2017 by Streetwind

[p1t1o]

On 6/12/2017 at 1:29 AM, StrandedonEarth said:

Real rockets are designed to deal with ascent heating, either with heat tolerance, throttling back at key times, trajectory planning, or a combination thereof.

/thread

[wumpus]

Apollo hit max-Q at .8km/s or 2900 km/hr.  Not exactly blackbird speed, but it should be causing heat issues for the command module.  Depending on how you would term "exit the atmosphere", it was probably going twice that when it left.  Also, Apollo lifted off at something like 1.1TWR.  Falcon 9 FT (and later) launch at 1.3+, so expect them to have more issues on ascent (the shuttle flew off the pad at TWR=1.26 but didn't seem to match Apollo's speed in the atmosphere.  Maybe I'm misreading the poorly labeled graph).

https://upload.wikimedia.org/wikipedia/commons/2/2c/Apollo17_Ascent_Trajectory.pdf
https://www.nasa.gov/pdf/466711main_AP_ST_ShuttleAscent.pdf

[regex]

One of the reasons rockets have payload fairings is to protect the payload from aerodynamic heating so it's reasonable to assume most, if not all, orbital rockets experience that on launch. The nature of Kerbin and our desire to see effects during reentry means we see them on launch as well, even if they represent a lesser heating load.

If I were to hazard a guess I'd say that the Shuttle throttled down before max-Q because it had a much more complex, open, and potentially fragile (in terms of connection points) airframe. Reducing load during such a critical period would ensure launch safety. More compact and simple airframes (like Minotaur) can handle much greater TWR off the pad, and "rocket shapes" in general have much simpler airframes and thus don't need such measures to reduce loading.

Edited June 15, 2017 by regex

[wumpus]

On 6/14/2017 at 11:39 AM, wumpus said:

Apollo hit max-Q at .8km/s or 2900 km/hr.  Not exactly blackbird speed, but it should be causing heat issues for the command module.  

Now that I think about it, Micheal Collins mentioned* that you couldn't see out of Apollo during launch/[atmospheric] ascent.  I'm pretty sure the heat shield covered the windows and was removed along with the escape tower once they were in space.

*"Carrying the Fire" basically an autobiography/insider's view of Apollo and Apollo 11 in particular.

[Phineas Freak]

3 minutes ago, wumpus said:

I'm pretty sure the heat shield covered the windows and was removed along with the escape tower once they were in space.

That is correct. Apollo used the a fiberglass Boost Protective Cover over the CM to protect it during the atmospheric phase of the flight and the jettison motor plume. It was part of the overall LES structure and was jettisoned with the rest of the LES hardware (abort motor, jettison motor, mounting structure, canard structure etc). There is a nice document on NTRS that describes it in detail.

Also, the LAS on the Orion is pretty much the same thing.

[Superluminaut]

On 6/13/2017 at 0:59 AM, Streetwind said:

@Superluminaut If you want an actual solution you can implement, I can tell you how to edit physics.cfg to make it happen.

However! Changing those values changes the way KSP displays atmospheric effects in general. You can shift the point at which white effects transition into red effects to a higher speed, so during launch, you at least don't see flames; but in return, that means that a reentering capsule will stop showing flames while still going faster and being higher up than normal. Similarly, you can tweak the fudge factor for atmospheric effects that forces flames to appear at the low speeds of the stock game, so that you need to go faster to see effects at all. But then a reentering capsule will show less effects as well.

Another thing you could do would be to install a mod like Sigma Dimensions and use it to make your atmosphere smaller. Real life rockets don't show flames during ascent because 90% of their acceleration happens outside the atmosphere. which is extremely thin relative to the size of the Earth. Kerbin's atmosphere is way too thick by comparison, hence the reason why KSP rockets spend most of their time accelerating inside the atmosphere and provoking reentry effects. If you make the atmosphere of Kerbin some 20-30 km thick instead of 70 km, then you'll reliably stop seeing atmospheric effects during ascent. Of course, the downside is that reentry becomes a much more dangerous and harsh proposition, much like it is in real life. Also, planes won't be able to fly nearly as high.

(EDIT: You could also make your planets larger instead of making the atmospheres smaller. But that, of course, changes the entire game drastically.)

Those are the only implementable solutions you have. You cannot selectively avoid atmospheric effects based on arbitrary personal opinions like "but this is a launch". Physics doesn't work that way. If you go at speed X through air at density Y, you get flames; it doesn't matter if you're going up or down. If neither solution appeals to you, then I'm sorry to say, you're out of luck.

I recall the save file containing info such as landed, and orbiting. Would it be possible the change the way atmospheric effects are displayed if landed or orbiting? 

[Starman4308]

1 hour ago, Superluminaut said:

I recall the save file containing info such as landed, and orbiting. Would it be possible the change the way atmospheric effects are displayed if landed or orbiting? 

No, because your situation is "Flying". You go too fast in atmosphere, you get shock heating, end of story.

[Streetwind]

1 hour ago, Superluminaut said:

I recall the save file containing info such as landed, and orbiting. Would it be possible the change the way atmospheric effects are displayed if landed or orbiting? 

It's possible that a plugin could do this. Problem is, it doesn't help you much, because there aren't very many situations, and it has all the side effects of editing the physics constants - plus additional ones on top of that.

Say you write a mod that removes atmospheric effects when flying in the lower atmosphere, but not when flying in the upper atmosphere. That's the maximum level of detail that using situations can offer. What you now have is a hard cutoff at 18,000 meters on Kerbin, above which you get reentry effects, but below which you don't. This has the following implications:

- A rocket that launches with a high TWR will see no effects up until 18,000 meters, and as soon as it passes that mark, gets instantly enveloped in flames.
- A reentering capsule instantly loses all effects as soon as it passes below 18,000 meters, regardless of how fast it is going.
- A plane that cruises around that altitude may rapidly flicker its effects on and off, looking like a graphics glitch.

All in all, it's a profoundly ugly and immersion-breaking solution that takes more than a hundred times the effort of a simple MM patch for the physics constants for a worse result that also breaks everytime KSP updates. Nobody will bother doing such a thing, and even if someone did, you would end up not liking it in practical application.

Edited June 15, 2017 by Streetwind

[KerikBalm]

as people have said in this thread before, its a matter of kerbin not being Earth. Its really small, yet its atmosphere isn't so small.

http://wiki.kerbalspaceprogram.com/wiki/Kerbin#Atmosphere

Quote

The atmosphere of Kerbin is patterned after Earth's U.S. Standard Atmosphere (USSA), though with the vertical height scale reduced by 20%. Kerbin's "base" temperature and atmospheric pressure can be very closely approximated using the equations of the USSA

Earth has as 10.6x bigger radius than Kerbin, but its atmosphere is only ~1.25x  larger by radius for a given atmospheric pressure/density. On top of this, there is no residual drag after a certain point, so no need to reach a higher orbit than 70km, whereas on Earth an "equivalent" altitude of 87.5 km will decay very very rapidly.

So while getting into the thin atmosphere, one must go proportionately much higher, but then one can circularize much lower. The result is that an optimal ascent results in you going much faster in a much thicker atmosphere (proportionately speaking), and this one gets shock heating on ascent.