[Bug] aerobraking on Jool in 1.05 (1.04) is not possible anymore ?

[zero1m]

didnt find any answers on steam so here we go...

I just have loaded (once again) my saves from 1.02 and I have instantly exploding ships which trying to enter Jool's atmosphere at 199 km which isn't possible because higher limit is 200 km and it is must be quite discharged there. Can it be related with new heat management system ?

pls confirm

also, ship was flying without heatshields/radiators.It has just crossed "edge" of atmosphere (with pressure < 0.006 atm ) and get overheated in 1-2 seconds !!!

KSP  Version  1.0.5 (1028) ,  1.0.4 ( 00861)

OS: WinXp 32 / Win 7 64 bit

Edited December 17, 2015 by zero1m
update from 1.04 to 1.05 same bug

[Starwaster]

First, you're going to need some kind of heat shield on your craft for aerobraking / aerocapture at Jool. You're coming in way too fast to get away with an unshielded craft.

Second, even with shielding you're going to have trouble because the atmospheric composition of Jool is the same as Kerbin, so the density for any given pressure value is the same which means heat transfer is going to be high. Jool should have a composition that is largely hydrogen and lighter gasses which means it should be less dense. KSP 1.1 should hopefully see some fixes in that area, but for right now there is Real Heat which has a more realistic atmosphere for Jool that you should find more survivable. (with shielding)

[Farex]

Hello zero1m,

I have had the same "issue" with jool. You may want to read the very useful tips in this thread :-)

http://forum.kerbalspaceprogram.com/threads/134943-Aerobraking-at-Jool-how-to-do

[zero1m]

Hi Farex, sorry, searched but missed your thread. So it is confirmed. Jool's atmosphere is glitched now. thanks

I hope devs will fix that somehow or they will raise upper limit of Jool's atmosphere.

If this "feature" is intended, pls respond

p.s 2000K in 1-2 seconds really hurts

Edited September 28, 2015 by zero1m

[Enceos]

Hi Farex, sorry, searched but missed your thread. So it is confirmed. Jool's atmosphere is glitched now. thanks

I hope devs will fix that somehow or they will raise upper limit of Jool's atmosphere.

If this "feature" is intended, pls respond

p.s 2000K in 1-2 seconds really hurts

The RealHeat mod will fix this issue for you. You probably won't need this mod when KSP 1.1 comes out. Also take a look at Inline Ballutes to help you with aerobraking without diving too deep into the atmosphere.

[Farex]

I hope devs will fix that somehow or they will raise upper limit of Jool's atmosphere.

Raising Jools atmo seems like a good idea to me. Because, Jool is just HUGE, reaaaaally HUGE massive extremly large. Me thinks that the 200km are not enough. Maybe something like 500km or so?

What's with Jupiter? Do we know where it'S atmo ends?

[yorshee]

Putting a ton of heatshields around your ship with radial attachment points should work in theory, but I haven't tried it yet. I agree that Jool's atmo heats you up way too quickly.

[Padishar]

Raising Jools atmo seems like a good idea to me. Because, Jool is just HUGE, reaaaaally HUGE massive extremly large. Me thinks that the 200km are not enough. Maybe something like 500km or so?

What's with Jupiter? Do we know where it'S atmo ends?

Well, since it is a gas giant and has no surface to speak of, it is a bit tricky to tell the difference between the atmosphere and the planet.

https://en.wikipedia.org/wiki/Atmosphere_of_Jupiter

[Starwaster]

Raising Jools atmo seems like a good idea to me. Because, Jool is just HUGE, reaaaaally HUGE massive extremly large. Me thinks that the 200km are not enough. Maybe something like 500km or so?

What's with Jupiter? Do we know where it'S atmo ends?

It's not just an issue with its altitude. That's not even the main issue. Raising the altitude of its atmosphere won't be as much use as reducing its density as I said before.

Installing Real Heat will make Jool survivable and relevant for aerobraking because it reduces the density of the atmosphere and therefore rate of heat transfer is reduced as well.

(and no planet's atmosphere has an obvious boundary. It simply becomes lower and lower in pressure until there's no longer any point in measuring it.)

Edit: An example of a Joolian entry. As you can see from the altitude I've just hit the top of the atmosphere. Dynamic pressure is almost 14 pascals. 1 pascal is 1 newton of force spread over 1 square meter. (or 1 kg per meter per second). That's the benchmark for dynamic pressure for a reentry from a standard orbit around the given planet. There's not much point in in having the atmosphere any higher. Look also at the amount of drag currently being generated. There's reasons why it's as low as it is.

Clarification: I mean reasons why the top of the atmosphere is where it is and it is because of expected dynamic pressure and drag at that altitude. Any higher and it ceases to be relevant in terms of drag.

Edited September 28, 2015 by Starwaster

[zero1m]

Thanks for tips guys.

Starwaster, I have compared pressure magnitudes of Jool and Kerbin (from wiki), with the same values (+/-) 500 Pa, so just after your ship have crossed "edge" of Jool's atmosphere (198-199alt) it instantly will be put in the same conditions as in Kerbin (but lower than 30km) at speed >8000 m/s !!!!

Farex, I also tried calculated approach with Tylo (Gravity assist for lowering speed) and there is no much difference (but of course it is solution anyway ). I can lower vessel speed (and enter Jool system), but it not so effective as aerobraking.

Edited September 29, 2015 by zero1m

[Farex]

I took Tylo and Val, retrograde flyby. Try to use Laythe for aerobrake. I just needed something about 200 m/s for the capture (of course, more was used for an OKish orbit).

[Starwaster]

Correction on something I said earlier:

Real Heat isn't altering the actual density of the atmosphere, only calculating its effect on heating differently.

[xebx]

If you can correctly set a Tylo and Laythe flyby/gravity assist, you can have a 100% free Jool orbit (Pe 1000km, Ap near Laythe in my example). No aerobraking needed.

That's what i get if i don't slow down at Laythe (500 m/s capture burn) on this pic :

note : Real heat seems to be an interesting mod, i don't like the way the skin temperature/stock can increase very fast. Skin temperature is not a bad idea but it should transmit heat faster to the body.

Edited October 2, 2015 by xebx

[Starwaster]

note : Real heat seems to be an interesting mod, i don't like the way the skin temperature/stock can increase very fast. Skin temperature is not a bad idea but it should transmit heat faster to the body.

That would neuter heating and make it pointless.

But if you want it to do that then it's just a few key presses and mouse clicks away. Alt-F12 to bring up the menu. Click Physics then Thermals. Increase conduction factor. (that will increase ALL conduction. Skin-Skin (part skin-part skin), Skin-Internal and part-part (internal).

[Scarecrow88]

Before realising there was a problem now with aerobraking at Jool, I have just tried to do exactly that. As soon as my craft dipped below 200k, instant kaboom. Something definitely not right there.

[xebx]

That would neuter heating and make it pointless.

But if you want it to do that then it's just a few key presses and mouse clicks away. Alt-F12 to bring up the menu. Click Physics then Thermals. Increase conduction factor. (that will increase ALL conduction. Skin-Skin (part skin-part skin), Skin-Internal and part-part (internal).

Thanks for the tip, i will try setting it from 20 to 21, just to see how it acts. I don't think it would make heating pointless, i'm still using 99% aeroheatgeneration (lot of people are setting it to 0 or 50%) and more conduction would make heat more realistic imo.

About Jool aerobraking at 9000 m/s, i think it 100% logical to have instaexplosion, it would be cheating to be able to + you can aerobrake at laythe at a lower speed with a less dense atmo (aerobrake at laythe is very safe at 40km) using the good gravity assists to slow down before encounter.

The fact is old players have the habit to aerobrake at jool, the easy way : just set aeroheatgeneration to zero (or mod jool atmo); or try to improve your navigation skills by using good gravity assist, the hard way...

Edited October 1, 2015 by xebx

[zero1m]

Version  1.0.5 (1028)

{repeat of audio transmission} "mayday, mayday, sudden temperature buildup at 195km, we are now above Jool, it was good seconds earlier and now.... oh god it coming from nowhere, we havent even reach an atmosphere, we are losing..... shhhhhhhiiiii.........[something cracking] [sound of multiple explosions] [user's gurgling] " {end of record, contact lost}