Proper altitude for Duna aerobraking in 1.04?

[OscarJade]

I know the atmospheric model has changed things...but I'm about to do some missions on the red planet and have never used aerobraking. Any tips? Thanks in advance as always!

[Reddeyfish]

A quick google search reveals this post for 1.0.2:

The sweet spot for aerocapture is usually (depending on the angle at which you intercept Duna and thus your speed when you get there) between 17-22km. Any lower and you usually end up lithobraking. (http://forum.kerbalspaceprogram.com/threads/118934-Duna-Aerobraking-capture-landing-Observations-in-1-02/page2)

I'm guessing it's still about the same in 1.0.4. Go as deep into the air as you can without hitting the ground.

Edited July 12, 2015 by Reddeyfish

[OscarJade]

Thanks! I will probably err on the high end - lithobreaking hurts!

[seyss]

what I do is save after entering SOI and try different periapsis to see which gives me orbital insertion using aerobraking

[FancyMouse]

yeah 17km is also what I shoot for. Heavier lander I adjust lower. Also try to avoid mountains.

[cephalo]

Wait up. 1.04 changes these things drastically. Aerobraking is much less helpful now, as parts will explode well before you get a solid benefit in terms of slowing your velocity. If your speed is very high, make sure your sensitive bits are not exposed, lest they be kicked harder than they can withstand.

[Geschosskopf]

A quick google search reveals this post for 1.0.2:

The sweet spot for aerocapture is usually (depending on the angle at which you intercept Duna and thus your speed when you get there) between 17-22km. Any lower and you usually end up lithobraking. (http://forum.kerbalspaceprogram.com/threads/118934-Duna-Aerobraking-capture-landing-Observations-in-1-02/page2)

Hehehe, seeing as you were quoting me, I will say that I have NOT YET tried aerocapturing at Duna in 1.0.4, but expect to before midnight tonight. In 1.0.4, both the heat and the aero models changed significantly. So I would NOT rely on what I said above, which was for 1.0.2, in the 1.0.4 we have now.

[FancyMouse]

okay I forgot my Duna lander is equipped with airbrakes - it still works like charm (it slows you as long as you stay in atmosphere long enough, no matter how fast you are)

Heat is not a concern. Duna atmosphere is still thin.

However if I disable my airbrakes, I do find difficulties - 10km still gets me back to orbit (at least it captured)

does seem it's time to wait for a systematic analysis.

EDIT: tried some more. my observation is: with airbrakes, still shoot for 15~20km and pretty much anything would work. without it - your margin is determined by your entry velocity, and everything is pretty tight. conclusion: spam airbrakes!

Edited July 13, 2015 by FancyMouse

[Geschosskopf]

OK, I just did my 1st Duna aerocapture in 1.0.4 with 100% heat. The ship was a 2.5m probe with a puodle, the 2-section gray tank, and a fairing under which were to small probes. This hit Duna's atmosphere doing about 1500m/s and required a Pe of 16km to capture, which resulted in an Ap about twice as far out as Ike. Although there were some decent flames visible, nothing got hot. Higher altitudes resulted in no capture. Circularizing from the aerocapture Ap to a 100km orbit without any additional aerobraking required about 150m/s worth of burns.

I've got 2 more ships due to arrive at Duna in my next session of playing. Both of these are considerably larger and neither has a fairing. We'll see what happens.

[Bug_]

25km was a safe height for me at about srf-velocity 1km/second

[Edax]

From a high-speed non-window planetary transfer, the atmosphere of Duna can rip you apart at 15000m.