My next problem - EVE

[Pinchy]

So I have finally managed to go interplanetary and after getting my launch windows identified I have successfully explored Duna and Ike (unmanned and one way only) - but felt pleased to get there and land on both IKE and Duna.

Next was Moho (don't go there) I messed up the interplanetary transfer and got no where near.

Next on the list was Eve. So have managed to send 2 ships and have 1 ship that has just arrived. Its again an unmanned probe - almost the same as I sent to Duna. I have just a poodle engine remaining and about 800LF/Oxy.

My Velocity is almost 6000M/S so I thought I could set up an aerocapture (is that the right terminology) by plotting just in the atmosphere. After several attempts at 80K right up to 90K - I either explode instantaneously or just go straight out the other side. The lowest Peri I could do was 89,500 without exploding. I guess my velocity is just too high and I don't have enough fuel left to slow down in orbit. I have airbrakes and parachutes of which obviously the airbrakes do nothing as I can't get into the atmosphere before exploding.

Basically am I screwed as I don't have enough fuel and just have to do a flyby and capture some science above 90K and then let my ship go into distant space? With my second eve mission which is due to land in one day I may have to scrap my plans to land on eve and see if I can get into orbit around Tylo?

[KerikBalm]

In 1.02 I was barely aple to manage an aerocapture with a relative velocity of 5k.... I don't think you can make it with 6km in 1.04, without some serious heat shielding.

You could try using up near all your fuel just before you hit the atmosphere.

With less mass, you will decelerate faster in the atmosphere.

Due to the V^3 relationship of heating, you'll get much less heating at 5km than at 6km....

But really, you should wait for a proper launch window so that you don't arrive so fast.

[Corw]

Have you tried fiddling with maneuver points near SoI change point? Don't try just retro burn, try changing direction.

[p1t1o]

Perhaps you can make a reverse gravitational slingshot around Gilly? Bleed off some speed that way?

[Pinchy]

sorry I meant Gilly - not Tylo - thanks for correcting me P1t1o

Haven't tried that corw - but I am now in the SOI of EVE with my last quicksave - so think it may be too late for that

Kerikbalm - that's an interesting one if that relative velocity makes that much distance - I certainly have the time since my last quicksave to bleed of a lot of that 6K speed maybe down below 5K before I burn all my fuel - so I can try that if it makes a significant difference - once I have been captured I am hoping the aerobrakes and 8 chutes will be all I need for the end to my mission

- - - Updated - - -

Just on the launch window - I used the launch window calculator to get the correct launch window - I have launched exactly during that windo

- - - Updated - - -

interestingly the wiki which must be well out of date says you can set a peri to 70K for successful capture!! Errr really.....

[p1t1o]

Oh I didn't even notice, I had to check a map to remember the name of Eve's moon anyway!

Just in case its not clear, I don't mean just go into orbit around Gilly, I mean a close pass (open, not entering orbit) around the "front" of Gilly will drain velocity with respect to EVE, I'm not sure if you have the dV for it, but you might be able to make an entry to Eve possible? If Im explaining the obvious just ignore this

[mhoram]

The orbital velocity of gilly is between 274 and 945 m/s.

A gravitational slingshot can change the velocity at most by twice the orbital velocity.

Since the mass of Gilly is very low and with a velocity of 6000m/s, a gravitational slingshot around gilly will change the velocity just a little amount. My guess would be that under ideal circumstances the effect would be smaller than 300 m/s.

Also in order to get an encounter with Gilly at it's maximum speed, you would need to setup that encounter a long time before entering Eve's SOI.

Another idea would be to use a gravitational slingshot around Eve to get an other encounter with Eve in a few years.

[p1t1o]

Yeah I figured it'd only be useful if there's just a few m/s between you and survival.

[Superfluous J]

Yeah you'll be hard pressed to survive the atmosphere of KERBIN at 6 km/s. Eve will rip you to shreds.

Look up Hohmann transfers and go to Eve using one. Your ships will thank you!

[Cebi]

Slingshot around Gilly is like farting agains the wind at that speed. You can try what mhoram sugested. I would first try to set my periaps in upper atmosfere and try burn all the fuel as soon as you get near periapsis. You just need to achieve highly eliptical orbit and then you will gradualy break by diping into the atmosfere in several passes.

Also...do you have a heatshield? If answer is no, then there is no way to survive that encounter with atmosfere. Take it as a lesson and go design another probe

Edited August 27, 2015 by Cebi

[p1t1o]

Sometimes if you're desperate enough, you wish you had a fart left to aim into the wind!

[Pinchy]

- a fart is more than I need clearly... I do have a single heat shield once I have burned my fuel on the final stage. thanks for the comments and suggestions as always

[KerikBalm]

Kerikbalm - that's an interesting one if that relative velocity makes that much distance - I certainly have the time since my last quicksave to bleed of a lot of that 6K speed maybe down below 5K before I burn all my fuel - so I can try that if it makes a significant difference - once I have been captured I am hoping the aerobrakes and 8 chutes will be all I need for the end to my mission

Well, the atmosphere was also "thicker" in 1.02.

So some of the difference is 1.02 vs 1.04, some of the difference is the difference in velocity.