Eve manned mission.

[Mike]

So, first I need around 13k M/S of Delta V, also, what should be the TWR when on Eve's surface?

[Ecclesia]

Can't help you with numbers, since I tend to play KSP without any mods (except Alarm Clock as a QOL mod).

I do know you do not need a huge rocket to leave Eve atmosphere, depending on the objective. To only launch 1 Kerbal you can have a small rocket with 1 Vector Engine and a few tanks as first stage, and a energy efficient engine for last stage.

Unfortunately for me, my first mission / objective to Eve was to grab 600 ore and bring it to Gilly too, so I chose to do it all in one go and made THAT my first manned mission to Eve xD. Not only does that require a huge rocket standing at Eve surface, but I also needed to BRING that rocket there in the first place :P

[RoofCat]

I have a list of 10+engines I tested with Eve diver. Thrust and Isp values.

Basically you just attach all likely engines to a single 9t tank with inflatable heatshield and probe core, send to Eve orbit and start descent. Activate context menu for all engines, lock on screen. Make it fall. At key altitudes like 30km, 25km etc. start them all, hit escape for pause, write down readings, unpause, shut down all engines until next threshold.

It's not hard to send it there nor to make readings. That's how you do spaceflight - gathering relevant information before sending men.

Short - don't use anything but Vector, Mammoth and Darts on Eve at sea level. Thuds could be useful for rover climbing assistance eventually, but not for flying. 15km above Eve is where you reach 0km "on Kerbin". Below 5 km on Eve is the worst due to how atmospheric pressure progresses (gas mass compressed by its own mass). Just do the testing, it adds to realistic approach.

[Toastie Buns]

Originally posted by despacito:

TWR when on Eve's surface?

Above 1 you silly sausage.

[MechBFP]

This is what could get me back to orbit (barely) from Eve sea level. Good luck. https://steamcommunity.com/sharedfiles/filedetails/?id=862335728

[RoofCat]

also there are some myths regarding Eve launches. Like the huge delta v amount. You need a lot of delta v, but those numbers are a lot smaller than some suggest.


1. You can't use Kerbin based delta v math for Eve!

You will have different Isp at low altitudes there and thus actually use smaller amount of delta v than it looks or would have with the same design on Kerbin. Your engines are less efficient - that's true. But the delta v depends on that efficiency as well so it is reduced in numbers too. Isp is fuel (Lf+Ox, all propellants total) mass burnt for thrust kN. Your thrust is much lower on Eve due to 5x higher air pressure at sea level. So you just use more fuel to launch thus your Isp is lower and thus the theoretical delta v of certain stage. You burn much more fuel, but you don't use as much increased delta v.


2. It's quite hard to find accurate Isp for Eve launch.

First it depends on engines used. Then you would have to make a video and watch it on replay to make accurate notes and find out weighted average (fuel spent at particular Isp) from multiple input values as Isp changes a lot during launch there and the progress is not linear! Can be done with a lot of pausing too I guess. I for example have no idea how much delta v my own Eve lander did spend on ascent in real, Eve numbers. I could quite easily do that in Kerbin values as Isp changes quickly and by a rather small value there, but that would be off by like 30% for Eve.


3. My best wild guess would be you need actually just around 6ooo..7ooo m/s to launch from Eve to stable low orbit. In local delta v values with proper Isp used!

A lot of people using calculators for KSP and claiming it's all about math are actually a bit dumb and can't interpret numbers properly in the first place. So they may be speaking about 8ooo..11ooo m/s in Kerbin values, which is complete bs. As different engines get different hits on Eve and it is simply not correct in regard to how delta v formula works and Isp changes.


4. TWR number acts the same everywhere. You need above 1 to lift off. Optimal being somewhere around 1.5 (on Eve it may actually be a bit lower due to very high drag you will encounter during start anyway). The possible value for the same ship design changes everywhere though.

Your weight changes (in kN, actually N in Si system where you also use kg instead of t - it is your mass multiplied by local gravity, but t and kN works too as they both are x1000) and then engine thrust changes too due to atmosphere where it is present. Thus your thrust to weight proportion is strictly local and should be considered for every new body. For vacuum spots you just adjust the weight part. Like Mun having 1/6 or Kerbin gravity means you have 1/6 of weight there and thus your engines can lift 6 times more mass (t) than they would on Kerbin. Rather simple adjustment. While for atmospheric worlds both numbers change (thrust as well) and thus it is a bit harder to find accurate TWR. You need accurate thrust value for sea level to do the math.

[Jupiter3927]

Personally, I ignore TWR and compare accelerations.
Your engines will produce thrust and your ship has mass so you can do F=MA to get A=F/M.
The planets will also throw an acceleration on your ship and you can measure this with the gravioli detector.
Eve's acceleration due to gravity at the surface is 1.7G or 17m/s^2.
Since the standard TWR is 1.5, you would need to do 1.5*17 to get 25.5m/s^2 for your target acceleration.

ISP and engine thrusts at Eve's surface are limited by the 5x thicker atmosphere.
The best method to figure out numbers in-game would be to drop some engines on Eve's ocean and have them float there while you note their thrust and ISP stats.
The Vector and Aerospike engines tend to work better on Eve's surface so definetly try those.

After all that, it turns into the standard 'design a rocket' thing you do all the time for Kerbin.