Eve I: a rocket for Eve landing [0.16 / 0.16 + Mechjeb]

[r_rolo1]

Inspired by Guard13007 Eve going thread and after the fiasco of my last Eve rocket ( that was krakenized still in the atmosphere :| ), I decided to make a less Kraken-friendly ship, that could still land a Kerman in Eve.

Thankfully Nova came to the rescue and gave some important intel:

I'll help you guys out a little bit, here are the latest stats on Eve:

(may change, they've been changed up quite a bit so far)

Radius: 700km

Surface gravity: 1.7g

Atmosphere density: 5x kerbin

Rotation period: 22.5 hours

Semimajor axis: 7440000km

Eccentricity: 0.03

Inclination: 0.025

Knowing this, and basing upon some of the work Guard13007 did ( especially on the Eve lander issue ... the lander stage is a heavily modified version of his last posted lander ), I've decided to work in my Confusion A to make a little less complicated ( thus less Kraken susceptible ) and put one leaner lander on top, in the hope that it could get to the orbit Nova posted. So I got to this:

First, the ship in pic has mechjeb, but it does not need it to fly if you're good enough pilot. You just need to be extremely careful in the launch staging, to avoid waste ( it is a fairly complicated staging ) and empty tanks hitting the central engine ( it can happen if the ship is ill manoeuvred during empty tanks ejection ). Second, the ship without the solid boosters could also get into the desired orbit but it would leave little fuel for manoeuvres ( I plan to use mostly aerobraking to slow down the ship to a Eve centric orbit ( or even a direct drop if I feel daring enough ) so it is not needed as much as that if Nova data above ( especially the atmosphere density ) is to be relied on ) so I decided to add some extra punch.

Anyway, flight plan:

- Get into a 70x70 km orbit or as close of that as humanly ( or mechjebly ) possible... makes the ( supposed ) Eve injection burn more efficient. As I said above, be extremely careful with the staging.... I started turn at 10km, but I think that can be optimized. Anwyay you will most likely need to go full throttle until you circularize so no problem with the Fuel bug

- Wait until +/- 40º after sunrise line ( this is on the day side of Kerbin ) ... I need to really calculate this using one of the threads in the How to section since this was completely eye-balled. Then do a full burn until the Pe of the Kerbol part of your orbit is 7440000 km or close enough ( you will probably need some low throttle burn in the end of this to fine tuning )

My better try left me with a 1/3 of big tank to later orbit corrections:

[spoiler=]

Craft files for both Mechjeb and stock versions here . For the slightly refined version ( Eve I a ) , see here

Edited August 27, 2012 by r_rolo1

[Commander Zoom]

Personally, I'm not even going to attempt Eve or other planetary missions until we get docking, orbital rendezvous, etc etc and can do it in a sane fashion, rather than having to launch the whole thing from the ground. But good luck to you and the rest, I guess.

[r_rolo1]

Fair enough To be honest I'm pretty sure that it will be impossible to make the full trip in a single rocket launched from Kerbin ( same as in RL Mars and Venus ). As such, this is simply a one way trip rocket ( well, it is planned to launch the capsule back into orbit for a hypothetical rescue ).

Edited August 23, 2012 by r_rolo1

[Spartan117]

I agree with r_rolo1. It would seem futile to attempt (but no less entertaining and informative) to try and a Kerbin-based launch to Eve and back. I know my computer couldn't handle a craft of that complexity. Heck, the redesigned Standard Mun Rocket I got from the Exchange before the forum switch-over (and release of 0.16) slows launch events into a slideshow.

[r_rolo1]

Unfortunately I discovered that Eve I is taking advantage of a rather esoteric fuel bug ( yes, another bug ... completely unrelated to the the non-full thrust one ) that cuts the fuel consumption in half in certain situations. See here for more details. I think it might still work but it will definitely not be as efficient as I posted it...

[r_rolo1]

Ok, as there were some issues with the staging and the number of parachutes, I decided to make a slightly refined version of this called Eve I a. You can find it in the opening post, both in stock and MechJeb versions. And as there were some doubts about the flight plan and staging, I guess, I will just explain it a little ...

First of all staging. Before all, it might be useful to point out that stages 0-3 are the ones that constitute the lander ( except for the engines , that fire all at start except for one ), while stages 4-8 ( in the revised version ) are the ones used to put the ship in orbit and to make the interplanetary injection burn. Anyway from bottom up:

- stage 8 fires all engines except the smaller LV

- stage 7 drops the solid boosters out. The fuel in it should be half spent in the time the SRB light out

- the next 3 stages drop the outer tanks, starting by the lowest ones and then climbing. Activate the next as soon as the fuel dries out

- stage 3 separates the central big tanks and 3 of the aerospike engines out also firing the small LV. In other words it separates the lander out. It is recommended that you do this with the engines out, but it is not such a big deal.

- stage two are the parachutes. In the revised version I increased their number to 6, due to some cases of parachute breakup .

- stage 1 separates the tanks that have the lander legs. thus it should not be activated before landing.

- stage 0 separates the lateral tanks and the aerospike engines.

Now on flight plan ... well, due to the absolute need of using Mechjeb in my comp to launch this ( I tried to record a video to put here and ended with a 1 fps mess until it got out of the atmosphere ... ), I used the regular flight plan of mechjeb with the max altitude set on 72 km. This is by far not optimal, but at this point I can not be bothered to refine it. Then i circularized the orbit at 70 or 71 km.

As the rest for the push to Eve "orbit" is already posted, I'll just add something for the lander tester. I normally start in a 70*70 km Kerbin orbit and then burn to lower the Pe to 30 km ( it could easily be less , but I play safe in kerbin landings ). Then I either put the Mechjeb in retrograde or do the the retrograde positioning manually until you hit +/- 22 km, where you can deploy the chutes. Then you can take the mechjeb or the SAS out, because the chutes will keep the ship aligned ... and will open at little more than 400 m above ground. At that time you should deploy the legs and prepare to burn a little to decrease the velocity to 3 m/s or less on impact ( you can let that to mechjeb "Land" command in the Landing window if your comp lags badly like mine ).

By this time you should have a almost full ship, so it is time to fly again Put the ship in full throttle and activate stages 1 and 0 as soon as the tanks get dry in the bottom stage. I used again the same flight plan for mechjeb ( i know, lazy ). The lander needs to be kept at low throttle ( the good ol' Goddard problem ), so there are certainly issues with the fuel bug ... so I reserve the right of putting more fuel in the lander stages.

If this explanation is not enough, see pics here ( P.S : start from the bottom )