Kerbin aerobraking at 5 Km/s?

[Jovus]

Eve, guys. The body you're looking for is Eve, not the Mun. Only Eve is nearby and has the necessary gravity well.

 

@NeverEnoughFuel!! don't leave us in suspense here; try an Eve gravity assist and tell us how it works!

[NeverEnoughFuel!!]

On 10/4/2016 at 5:40 PM, Jovus said:

Eve, guys. The body you're looking for is Eve, not the Mun. Only Eve is nearby and has the necessary gravity well.

 

@NeverEnoughFuel!! don't leave us in suspense here; try an Eve gravity assist and tell us how it works!

There was nothing spectacular... just waited for transfer window and had a decent rendezvous with kerbin... except maybe protractor lied to me (again) and made me late two or three days, and that demanded one correction burn of about 600 delta V... entered kerbin SOI at 800 delta V ... gradually lowered orbit to LKO... pilot and science safely retrieved... mission successful ... My advice to whoever plays 1.1.3 don't rely on combination of protractor and formula based calculations in KAC for finding transfer windows... right combination of tools are KAC in "model" mod, and "transfer window planner" set to the same date which is given by KAC... KAC will tell you the date and time, and TWP will give you (one way with insertion) delta V and ejection angle (place to burn)... was practicing a bit... amounts of delta V and travel time for let's say Jool or Ello are staggering... luckily now I have warp drive... 

[problemecium]

I too have found that while Eve gravity assists may be a boon for moderating returns from Moho or the outer planets, the speed at periapsis after returning to Kerbin is still almost invariably well upwards of 4 km/s.

[Aegolius13]

I just did something similar but a little less extreme - braking at Kerbin from a Hohmann-ish Jool transfer for about 500 m/s total.  The trick was getting a gravity assist around Kerbin itself.  In effect, the idea was to use @Mad_Maelstrom's excellent Juno-style Kerbin-Kerbin-Jool gravity assist method, but in reverse.  

 

I started in Laythe orbit and waited for a Jool-Kerbin launch window.  Then I got the cheapest Kerbin encounter I could, with the encounter being close to (but not completely tangent to) Kerbin's orbit.  Then I fine-tuned the Kerbin encounter to provide a reverse gravity assist (slowing me down and thus moving my Apo in from Jool).  The key was to tweak the assist to leave me with a new orbital period of just about 2 years - meaning Kerbin and I would both get back to the same place in 2 years time.  The easiest way to tell the new orbital period is to look at your ETA to your new apo and peri projected by your maneuver node, take the difference, and double it.  

I got my Kerbin flyby and a new orbit that had a very similar periapsis around the sun but a much close apoapsis, in between Dres and Duna.  Then, at my new apoapsis, I burned prograde to push out my peri so that it produced an encounter with Kerbin, and was almost exactly tangent to Kerbin.  This took a little under 200 m/s.  At this point, manuever nodes were showing that I would need about 1500 m/s to circularize in LKO.  Since the delta v from LKO to escape is about 950 m/s, this means it was only going to take about 550 m/s to capture around Kerbin, which would allow me to aerobrake at my leisure. I also looked at doing a reverse assist around the Mun, but it was not enough to help me.  That means it's time to aerobrake. 

So, just before hitting Kerbin atmosphere on the second pass, I spent about 300 m/s to burn retrograde.  This got my peri down to around 45 km altitude, which I hoped was enough to capture but not enough to fry me.  It worked - my ship got very hot but did not blow up, and I lost so much velocity my new orbit only went about halfway to the mun.  Then it was just a matter of doing successive small aerobrakes until I hit an 80km orbit, and circularizing.  

Previously, I had played around with Eve assists for this, but I think Kerbin is easier.  While Eve's higher gravity can generate a bigger assist, Kerbin has a few advantages.  First, it's much easier to get the second capture, by using the one-year rule.  Second, while Eve assists had me intersecting Kerbin at crazy angles, with the Kerbin assist it was inexpensive to get my second encounter at a point tangent to Kerbin's orbit.  And since Kerbin had enough oomph to get that 2 year resonant orbit, I did not really need any more gravity pull than Kerbin was providing.  But with a more extreme velocity like OP's, this might potentially take a couple passes.