Delta V to ascent Eve

[Spyros]

I am relatively new to KSP and I tried to find out how much delta V is required to ascent from the surface of Eve to orbit so that I can use KER and build a vessel accordingly . The results were confusing as the numbers that I found around the web were very different especially due to some of them being outdated (according to my understanding due to version changes). In addition to that, I figured out that there is a big misunderstanding about how to read delta-v maps when it comes to ascent values. I found posts where people claimed that delta v maps only use vacuum values (including for surface-to-orbit values), but I also found other posts reporting that the delta-v maps use atmospheric values when it comes to surface-to-orbit values. Furthermore, I found threads where both opinions were posted at the same time and some people were saying that the others were wrong as they didn't know how to read the maps  (e.g:  https://www.reddit.com/r/KerbalSpaceProgram/comments/8s2y4m/hey_guys_just_a_bit_confused_here_deltav_related/  ;  Chaos_Klaus' post). I still don't know what's the correct one.

The combination of all these is that it's get confusing for non-veterans like me to understand what's the required delta-v to go from the surface of Eve to orbit. What is an updated estimate of this value?  Please also specify if the number that you report is calculated in atmospheric or vacuum settings

Edited December 24, 2018 by Spyros

[Superfluous J]

The accepted number right now is about 8,000 m/s of vacuum dV, but that isn't enough you also need great atmo thrust so you need vectors, aerospikes, or... Something else. I don't remember the other one. I really like vectors myself, because if you get off center on Eve you need a lot of control authority to fight the atmosphere and get back straight.

Edit: And when I say "like" I mean "hate least." Eve is not very fun. Even getting to orbit isn't fun, so much as a relief.

Edited December 24, 2018 by 5thHorseman

[Pecan]

It depends whether you:

a. Go from sea-level
b. Start from the top of a mountain
c. Decide that everything everywhere else is more fun than an Eve ascent
d. Can I interest you in a holiday package at Dres's sun-drenched beaches?

Seriously - if you have to ask about Eve then you don't want to drive yourself crazy with it.  Go anywhere else.  Go everywhere else.  Do everything everywhere else before coming back to Eve!!

Edited December 24, 2018 by Pecan

[Foxster]

The thing about Eve compared to Kerbin is that you have to take the thickness and draginess of the atmosphere much more into account. 

It is possible to build a craft that will put a Kerbal in a mk1 capsule into orbit from sea level that weighs about 23t and with only ~5700 dV. That craft must be very carefully designed and flown though. A similar but non-optimal craft can weigh three times as much and take 8000+ dV to get to orbit. 

The "secret" is to make your Eve craft low drag. Make it thin and don't have anything not absolutely essential on board and certainly nothing that adds any drag; with one important thing being to drop anything not needed to make orbit before lifting off e.g. chutes, air-brakes, solar panels, science experiments, landing gear, etc. 

So, there is no simple answer to your question. It depends on your launch altitude, the draginess of your craft and the efficiency of your engine choices. 

[Laie]

17 hours ago, Spyros said:

I am relatively new to KSP and I tried to find out how much delta V is required to ascent from the surface of Eve to orbit so that I can use KER and build a vessel accordingly .

Building an Eve Lifter according to KER is difficult.

If you start near sea level, you will spend about the first minute of the ascent going straight up in thick atmosphere. ISP constantly improves as you go up, your TWR increases both with improving ISP and the fuel you burn off, increasing TWR means you climb faster so ISP improves even quicker... the compound effects are nearly impossible to keep track off.

That said, about 8km/s is a reasonable number if you start at sea level. Just be aware that this alone won't guarantee success.

If you find that you just can't make it, try again at slightly higher altitudes. Starting at 500m rather than sea level already brings a tremendous performance boost (see compound effects above).

Edited December 24, 2018 by Laie

[GRS]

Eve is pain, i used a 5000 ton rocket (second largest rocket) to deal with it, with 17200 delta Eve (a weird name a made for no clear reason), took me like 6 months of Hyperedit testing to find an ideal design, yet i end up changing it in 1.5, if you wish for a no docking lander, bring roughly 1500 m/s delta Eve into a stable orbit.

Edited December 25, 2018 by GRS