Will this craft land on Eve?

[Vllama87]

So I've just finished construction on what I hope is my first unmanned mission to Eve, but the thing is quite expensive, and I play with revert off, so I need this thing to succeed. Anyway:

Lander parts, bottom to top, according to descent orientation:

Heat Shield (43.90 Ablator)

Decoupler

Fuel Tank w/ 6 Landing Struts

Service Bay w/ Rechargeable Battery inside

Probodobodyne OKTO w/ 2 Communotron, 4 Photovoltaic Panels, a Barometer, and a Thermometer, all attached radially

Fuel Tank with 4 Parachutes, and 4 Tail Fins, attached radially.

Terrier Liquid Fuel Engine

 

I use the scaling mod, so here is a screenshot:

Any help would be greatly appreciated!

[Geonovast]

What you'll want to do is get just the lander by itself and take a look at the CoM.  You'll want that as close to the heat shield as possible.

Also toss the decoupler between the lander and the heat shield.  It's not necessary, the heat shields can jettison themselves and it's pushing your CoM further away from it.

[Geschosskopf]

The amount of ablator needed depends on the ship's mass.  The more mass, the more momentum, so the longer it's going fast and the more it burns.  Just guesstimating from the parts you list and comparing to my own experiments, you might need about 90-100 units instead of 44.

Landing a relatively small probe like that on Eve is actually pretty easy.  The only worry is not burning up, but if you've got enough ablator and the thing can keep it facing forward, that's really no problem.  Once the fires go out, fall very slowly due to the thick air, just barely fast enough to break stuff if you don't use a chute.  And you can go a bit small on the chute for the mass of the probe because chutes work better on Eve than Kerbin.

I would recommend eliminating the fuel tank, engine, legs, and fins.  Replace all that with a reaction wheel and a battery.  De-orbit with the last fuel of the transfer stage, use SAS to keep the heatshield going forward, and land on the heatshield.  Or jettison the heatshield once you've got the chute open.  And don't open the chute until you're only 1000m above the ground.  Otherwise, you're in for a VERY long, VERY slow descent even with 4x physical warp

 

 

[Cpt Kerbalkrunch]

Those antennas sticking out are unlikely to survive. In fact, anything not behind your heatshield is in peril on Eve descent. If you are allowed quicksaves, just set a high Pe (like 80-70km), and let Eve bring you down slowly. If you can't quicksave, though, this'll be troublesome, because you won't know where you're coming down. Eve has huge continents, but it's got a pretty big ocean, too. The slow descent will use up more ablator, though, so you'll need to balance the pros and cons. As said above, to land on Eve is easy, leaving it is much more difficult. For a small probe, I generally prefer a heatshield one diameter larger than my fuselage. This usually ensures an easy atmospheric entry.

[Vllama87]

Thanks for all the help! I've managed to get the center of mass as close to the Shield as possible, now I'm just trying to figure out what scale I should set it to...

On that note: how much Ablator would be necessary for a craft weighing 475kg, assuming I get it down to sub-2km/s before atmospheric entry?

Also, the antennas are the most important part of the entire probe, would simply putting them directly behind the heat shield be enough to protect them?

[Plusck]

Since you can't revert, I'm assumig you try to avoid quicksave too.

A word of warning then: do NOT jettison the heatshield until your chutes are fully open (or you have the control authority to turn around and have the heatshield behind you). Heatshields on Eve fall very very slowly too, and they oscillate.

[FancyMouse]

The font of the ship name and the version of KER is pretty alarming. You might be running an early version of KSP where all the above arguments might be invalid. That KER version seems to run on 1.0.* and IIRC 1.0.* contain a lot of heat and atmosphere changes (I remember a few of the versions it's extremely hard to enter Eve atmosphere where it was changed to be a bit easier later). So the best way is to test yourself.

[Vllama87]

2 hours ago, FancyMouse said:

The font of the ship name and the version of KER is pretty alarming. You might be running an early version of KSP where all the above arguments might be invalid. That KER version seems to run on 1.0.* and IIRC 1.0.* contain a lot of heat and atmosphere changes (I remember a few of the versions it's extremely hard to enter Eve atmosphere where it was changed to be a bit easier later). So the best way is to test yourself.

Yes, unfortunately I only have internet through a tether to my phone, and I'm limited to 500 MB/month or I would update. Anyway, the general tips I've received so far seem very useful! I'm currently in orbit around Eve looking for a good spot to land! Wish me luck!

[GoSlash27]

I don't think you need more than one 'chute. The atmosphere is extremely dense on Eve. Nevertheless, you might want to keep them. Parachutes are very draggy, even when stowed. This will help keep you oriented during entry. Plus, backups...

Best,
-Slashy

[Geschosskopf]

6 hours ago, Vllama87 said:

On that note: how much Ablator would be necessary for a craft weighing 475kg, assuming I get it down to sub-2km/s before atmospheric entry?

Also, the antennas are the most important part of the entire probe, would simply putting them directly behind the heat shield be enough to protect them?

Hmmm, 90-100 ablator was for full orbital velocity less a little bit to de-orbit.  If you slow below 2km/sec, maybe you could do with less.

As for the antennae, I agree that the whips sticking out sideways will likely burn off.  If you replace them with the double dipoles aligned parallel with the body of the probe, they'll probably survive the fire, but will likely only reach back to Kerbin if you have a relay in orbit over Eve.  If you don't have a relay. try the DTS-M1 instead.

[Aegolius13]

On 12/15/2017 at 8:05 AM, Plusck said:

Since you can't revert, I'm assumig you try to avoid quicksave too.

A word of warning then: do NOT jettison the heatshield until your chutes are fully open (or you have the control authority to turn around and have the heatshield behind you). Heatshields on Eve fall very very slowly too, and they oscillate.

I have had all manner of problems dropping heat shields on Eve, and having them smack into my ship.  The inflatable ones are the worst for this,  but the solid ones might be problematic too.  Another option is to keep the heat shield on and use it to lithobrake.

[fourfa]

21 hours ago, Geschosskopf said:

double dipoles ... relay in orbit ...

Looks like he's on 1.0.x so these won't exist?