How do you build a spacecraft in orbit?

[drew4452862]

I have seen this in a lot of posts but even simple small ships docked together are very unstable.  Trying to get to eve, even refueled a small ship, but my orbital speed is always too high and i explode when entering the atmosphere.  How can i construct a ship in orbit with enough delta v ?

[Snark]

20 minutes ago, drew4452862 said:

I have seen this in a lot of posts but even simple small ships docked together are very unstable.  Trying to get to eve, even refueled a small ship, but my orbital speed is always too high and i explode when entering the atmosphere.  How can i construct a ship in orbit with enough delta v ?

There are a lot of options in KSP, but which ones may work for you will depend on your approach.

If you could post a screenshot of your attempted Eve mission, that would make it a lot easier for people to give specific suggestions.  What does your ship look like, how fast are you going when you hit atmosphere, and what's your Pe set to as you approach Eve?

It doesn't take a lot of dV to go to Eve, if you're following a good transfer window.  It only takes around 1000 m/s of dV from LKO, not much more than it does to go to the Mun (and if you count the fact that you can't aerobrake on the Mun, it actually takes less dV to go to Eve than it does to land on the Mun).  However, following a good transfer window is key.  Using a planner such as http://ksp.olex.biz/ can help a lot.

Arriving at Eve isn't necessarily hard, but there are a lot of ways to encounter problems.  Some examples include:

• if you don't have a heatshield
• if your ship has too much mass behind not enough heatshield area
• if you're hitting the atmosphere too steeply
• if you didn't follow a good transfer window and are arriving at Eve going too fast

 

[Superfluous J]

There are 2 main viable options:

1) Mod it 'til it bleeds. In particular a mod like KIS (or KAS, one of the two. I never remember which does what) has attachable struts that you can link together with an IVA kerbal. There are other mods that also just do struts, but that's the most prominent.

2) Build a train. You can't wobble all over the place if you pull your payload instead of pushing it. This is the way I do it most of the time. I like to build a "cage" structure with engines around the outside, and attach my payload in the middle so it's inside the "cage" and being pulled. That way, your engines can still be behind the center of mass.

Edited April 7, 2016 by 5thHorseman

[drew4452862]

that is the ship i used, but i am thinking it was my transfer window, must have been going to fast trying to intercept the planet.  Got some fuel out there anyway lol.  I'll try it again using that link and see how much fuel it save me.

 

[Snark]

8 minutes ago, drew4452862 said:

that is the ship i used, but i am thinking it was my transfer window, must have been going to fast trying to intercept the planet.  Got some fuel out there anyway lol.  I'll try it again using that link and see how much fuel it save me.

Actually, your speed looks pretty good-- if you're only going 2554 m/s when you're already in atmosphere, that's really good for Eve approach.  That's considerably lower than Eve escape velocity, so I assume you must have used a lot of retro-thrust to slow down before entering atmosphere.

However... two problems.

First, I'm not seeing a heat shield.  (It's kinda hard to tell from the picture, the sky is dark and the lighting angle's not great.)  You really, really need to have a heat shield at Eve.

Second, you're descending way too steeply-- you're going nearly straight down!  That's going to cause problems even if you had a heat shield.  You need to approach at a much shallower angle.

Also... just to confirm, you're not planning to come back from Eve with that, are you?  It looks like a manned vessel, and there's no way that little thing is going to be able to get back to orbit.  I see no reason why it shouldn't be able to land okay (if it can get through the hot part of reentry), but ascending again is another matter.

[drew4452862]

I would like to get back to eve orbit to refuel and return to kerbin.  Not sure if that is going to work out lol.  

Sent another ship using the transfer windows, it is a bit more efficient but still going to the planet with a ton of speed.  Might be because i am not orbiting kerbin first?

 

I'll send up another ship with some kerbins, put a heat shield and see how it goes.

[Loren Pechtel]

Another thing you can do--send up the fuel on a separate rocket.  The stage that put you in orbit can be refueled and push you on to Eve.  You're only docked during the refueling, you're not trying to push wobble city around.

[drew4452862]

 

trying to test this right now.  seeing if it can last through rentry

 

UPDATE:  The ship was able to enter kerbin at 1600m/s with out the use fuel!

Edited April 7, 2016 by drew4452862

[Blaarkies]

1 hour ago, drew4452862 said:

I would like to get back to eve orbit to refuel and return to kerbin.  Not sure if that is going to work out lol.  

Sent another ship using the transfer windows, it is a bit more efficient but still going to the planet with a ton of speed.  Might be because i am not orbiting kerbin first?

 

I'll send up another ship with some kerbins, put a heat shield and see how it goes.

If you feel bad about abandoning Kerbals in space, then don't land them on Eve..that is a death sentence(or life imprisonment on Eve). Rather just get into a elliptical orbit(low Periapsis, High Apoapsis) so that you can get some Eve low orbit science. Use the high Apoapsis to get to Gilly and land there.

To land and launch back into orbit from Eve, you need a lander that is a tower of rocketry at least 50tons heavy...such beast doesn't even get a capsule into orbit, it barely gets a command seat into orbit. Eve ascent is considered one of the "top 5 most difficult" stunts to pull off.

[drew4452862]

damn, good to know... just thought I was doing it wrong lol.  wow... 4 thrusters dont even move my ship, trying to topple it.

[Blaarkies]

4 hours ago, drew4452862 said:

damn, good to know... just thought I was doing it wrong lol.  wow... 4 thrusters dont even move my ship, trying to topple it.

I think it happens to all of us...my first Eve landing crew thought they could take off in the same single-nuke-engine lander. So they had a permanent stay.

I stayed away from Eve atmosphere for a long while, until I had some 500 hours of xp. A lot of asperigus staging(120ton?) made it possible to get a lander can up there(this was before re-entry heating was stock). It was wobbly, unruly and generally frustrating. Now after a 1000 hours, better aero and re-entry I suddenly had lots of ideas:
- Command seat + small probe(built in torque wheel) + small battery.
- That was the payload, encased in a size1.25 fairing protecting the kerbal inside.
- Every stage below it has a mass of 2times it's own payload(every thing above this stage's decoupler is considered payload)

It was a 4stage rocket (vector on 3.75m tank -> poodle on a thin 2.5m tank -> 2sparks on a fl-200 tank -> ants on oscar tanks). Somewhere around 8000-9000 m/s dv if i remember correctly and a mass of 56tons...i still had to EVA and use kerbal jetpack to do the final dv.
This ascent vehicle landed unmanned, with 7x3.75m heatshield below(hexagonal symmetry), it had long ladders connected to pylons, the kerbal landed with a small science collecting rover nearby, climbed up those ladders and boarded "through" the fairing. Those ladders safely decoupled away at launch. Oh and you need super confidence at launching to orbit...10 seconds of manual control, then lock to surface prograde

It's really fun to do this(and you should!) but it definitely requires more than blind luck