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Is this capable of Eve Ascent?


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In the title lads. I built a heavy lander (around 54t) capable of carrying a crew of 2 Kerbals. I have built it with Eve in mind (hence the aerodynamic fairing, which carries the final ascent stage module); now I know that the required Delta-V is something around 6000-7000m/s but I have tested this lander on Kerbin - with 3320m/s Delta-V it was able to circularise an orbit of 500,000km above the surface (with about 15% fuel remaining). Considering the fact I've built a 1 man rival lander with double the Delta-V, this lander performed MUCH better in Kerbin testing. So would it then be capable of an Eve entry and ascent (to an orbiter waiting above)?

Pics can be seen here;
 

 

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Edited by Diddly Feelerino
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If everyone says 7000 delta-v, then I guarantee that your 3320 isn't going to cut it...

Remember Eve has both higher gravity (more losses during ascent) and thicker atmo (worse engine ISP during ascent). A rule of thumb (that might have been first said by @5thHorseman ?) would be that if it's going to get off Eve, it needs to be able to ascend from Kerbin, deorbit, land, and ascend again.

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1.8 Vacuum TWR at Kerbin in a TWR under 1 in deep Eve atmo. This is not taking off. (Assuming your engine was at 100% power, with KER on vac Kerbin settings in the first screenshot)

Also, 7k dV seems a bit on the light side (haven't been to Eve in a long time though so I may be wrong)

Edited by Gaarst
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10 minutes ago, Diddly Feelerino said:

@Gaarst - does it need to be over 2 TWR to lift from Eve?

Vaccuum TWR is not an indication of if a craft can lift off Eve or not. Its atmosphere is so thick that most engines produce close to no thrust at sea level.

To make sure your rocket will be able to take off, switch KER's display from Kerbin to Eve and enable atmospheric mode. If TWR is over 1 then you should take off (note that efficient launchers from Eve require very high TWR to get out of the thick atmo quickly).

Also note that Eve has a great pressure gradient: a difference of a couple kilometers landing site altitude can make the difference between a craft not taking off, and a craft making orbit.

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29 minutes ago, Diddly Feelerino said:

@eddiew - I guessed I needed better Delta-V, but on a 1 man lander with around 6500 Delta-V it performed better, leaving me confused.

Sorry, I'm confused by the 1-man lander thing... how did this perform better? A 1-man can with 6500 might well manage the double-Kerbin-launch test. With a delta-v advantage of 3000 I'd expect you to be able to fly a pancake to orbit and still have more left when you get there :S 

(Very very few people try to lift more than 1 kerbal off Eve at a time, and with good reason - it's gosh darn hard!)

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23 minutes ago, Diddly Feelerino said:

Ok, I've underwent a massive redesign of the rocket, and this is what I've come up with. 

6672 Delta-V (2318 in Eve atmos), TWR of 1.64 on Eve. What do you think?

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This looks perfect for a suborbital Eve flight :wink:

I've checked the numbers, and this dV map (which I believe is accurate) gives 8k dV (vac) to get into Eve orbit. Other than that the TWRs seem OK.

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Fly it up, get to orbit, de-orbit, and then get to space again in it, and you can get off eve, I think someone said this above also, but it's a pretty good measure for getting off that planet :)

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40 minutes ago, WillThe84th said:

This is why humans would probably never land of Venus, they would never be able to take off again. Well, that and the extreme temperatures, toxic atmosphere, and you know, all that other stuff...

Hopefully with the progress of electromagnetic shields we can make something capable of landing there, and leaving again, fusion powered engines, etc.

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MK III ready! Big bugger at 80 tonnes, but it has 8042 Delta-V in vacuum, capable of carrying 4 Kerbals and has a good TWR for all initial stages (after taking Eve's atmosphere into account). The final stage TWR is lower but that's only from ground level IMO. See for yourself!

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Just a few tipps:

- use less stabilizer wings to save weight and ditch the remaining ones with your first stage

- land the craft completely on chutes (and probably some separatrons to ease the impact)

- eject the landing gear  and empty parachutes/SRBs with your launch staging to save additional weight

- 8000 m/s will savely bring you to orbit from sea level, with a little reserve for piloting errors.

Edited by Frank_G
You land on chutes, not cutes :D
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1 minute ago, Diddly Feelerino said:

Now it has the problem of flipping on entering the atmosphere. Makes no sense as the weight is fully concentrated on the side facing TOWARDS retrograde (i.e. the larger fuel tanks). Like it flips non stop and ends up the wrong way round.......

I had this problem as well. Try placing AIRBRAKES at the very top. They don't even need to be in the airflow all the time. Just have them so when the craft starts to tip, they catch the air and nudge it back into place.

Here's a post with a ship that shows what I'm talking about:

 

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I tried a different approach for my EVE lander. Just landing on chutes was too risky for me and I wanted to maneuver around a little bit while landing. So I ended up adding drills and resource converters in an extra stage. I would land on EVE, produce fuel, drop the mining parts and then start. I'm currently not at home for screenshots but asparagus staging was pretty crucial and try not to overdo on TWR because if you gain too much speed to fast your craft will evaporate due to the insane friction in the dense atmosphere.

I also had one vector engine on my craft because I had the same problem as you with the flipping.

You should definitely get rid of that docking port on top and put on the shielded one, it makes a HUGE difference in atmosphere. The better aerodynamics of the shielded port make up for the added weight tenfold.

I had a middle section with a vector engine and 3 rings of 6 tanks with aerospikes around it, the first ring burnt symmetrical and the rest was asparagus.

Edited by Broco
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Are you using the inflatable heat-shield? It's good but creates a lot of drag which can flip your craft over. As 5th Horseman said, put some air brakes on a part that you can detach so you can get rid of them before take off. I've had to use up to 20 for some landers.

If you want to just test the landers ascent performance without having to de-orbit the thing and land it every time try the following. Make a basic probe ship, surround it in 2 inflatable heat-shields and Hyper Edit it to Eve. De-orbit and land it. Then, use the Vessel Mover mod to pick it up and place it wherever you want it on Eve. Save the game and then you can use the Vessel Movers spawn craft function to spawn your pre-saved lander directly on the surface.

Edited by Redshift OTF
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  • 2 weeks later...

SUCCESS! Finally built a Lander capable of Eve ascent. It's a heavier version of the 80T lander I built before; weighing in at 135T this beast is capable of lifting 4 Kerbals into low Eve orbit, with a few seconds of thrust remaining (tested from 1.4km Eve surface). With around 8,700 Delta-V it's time to embark on an actual mission!

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