Eve SSTO possibility?

[Jod]

The problems with a pure ion ship are twofold:

1. Partcount

2. You're flying on infiniglide anyway

I see only one problem:

1. 2 m/s^2 maximum possible acceleration even when in space. It's like watching paint dry. In slow motion.

As for infiniglide - yeah... I am currently considering the whole aerodynamics in KSP as a one huge bug. I'm thinking of just dropping the whole winged craft idea for Eve. You just can't compensate for fuel mass with lift because drag eats every last bit of your delta v that way. Even on Kerbin I find that vertical ascent saves huge amounts of fuel.

So far - the best configuration I came up with is an LV-N with Rockomax 24-77 boosters that are used to blast through the thicker atmosphere. And that is not even close to 8500 delta v at 1.7 TWR, more like 6000 delta v provided good piloting. I will try to squeeze more out of it but it seems i will need a second stage eventually as i just don't have the required Isp to keep all my mass with me.

[tavert]

The 24-77's have good TWR, second only to the Mainsail, but the low Isp limits the max delta-V you can get. See TWR vs delta-V chart (assuming a single stage with a single type of engine, zero payload and showing vacuum numbers but you can modify the payload and switch to atmo easily) here: https://www.desmos.com/calculator/fnjjcjvchw

Something I just tried on Kerbin was an orange tank worth of fuel, 4 aerospikes and 1 LV-N. This has Eve-capable starting TWR, but the effective delta-V depends highly on when you switch the aerospikes off, it's almost definitely not enough delta-V for Eve. One thing you can try to make up for the low LV-N TWR is a slower gravity turn, getting to a very high apoapsis on engines with good TWR, giving yourself lots of hangtime to try to build as much horizontal speed as you can before you come falling back into the atmosphere.

Edited June 11, 2013 by tavert

[Jod]

The 24-77's have good TWR, second only to the Mainsail, but the low Isp limits the max delta-V you can get. See TWR vs delta-V chart (assuming a single stage with a single type of engine, zero payload and showing vacuum numbers but you can modify the payload and switch to atmo easily) here: https://www.desmos.com/calculator/fnjjcjvchw

Something I just tried on Kerbin was an orange tank worth of fuel, 4 aerospikes and 1 LV-N. This has Eve-capable starting TWR, but the effective delta-V depends highly on when you switch the aerospikes off, it's almost definitely not enough delta-V for Eve. One thing you can try to make up for the low LV-N TWR is a slower gravity turn, getting to a very high apoapsis on engines with good TWR, giving yourself lots of hangtime to try to build as much horizontal speed as you can before you come falling back into the atmosphere.

Tried both configurations, 24-77 give slightly more delta v than aerospikes because their weight is smaller, improving the full/dry mass ratio. Still not enough for Eve, though I'm a horrible pilot. Maybe an ace could pull something off.

Edited June 11, 2013 by Jod

[Innuce]

It's going to take massive amounts of fuel any way you slice it. A large craft will end up being the solution here. Especially if we're talking a manned craft.

Has anyone successfully taken a manned, rocket-only SSTO spaceplane to 100Km orbit over Kerbin yet?

If one can accomplish this feat, I'm sure Eve wouldn't be too far out of reach.

[foamyesque]

It's going to take massive amounts of fuel any way you slice it. A large craft will end up being the solution here. Especially if we're talking a manned craft.

Has anyone successfully taken a manned, rocket-only SSTO spaceplane to 100Km orbit over Kerbin yet?

If one can accomplish this feat, I'm sure Eve wouldn't be too far out of reach.

You'd be mistaken. Rocket spaceplane SSTOs from Kerbin are a trivial problem (and have been done) compared to Eve. The problem is the mass ratios of the fuel tanks (and the additional mass of the engines, but the fuel tanks alone nearly kill it).

[Jod]

It's going to take massive amounts of fuel any way you slice it. A large craft will end up being the solution here. Especially if we're talking a manned craft.

Has anyone successfully taken a manned, rocket-only SSTO spaceplane to 100Km orbit over Kerbin yet?

If one can accomplish this feat, I'm sure Eve wouldn't be too far out of reach.

I have taken a probe up to 90 000m with some fuel to spare and posted pics in post 47 of this topic. A seat can easily be added for transporting kerbals.

http://forum.kerbalspaceprogram.com/showthread.php/34221-Eve-SSTO-possibility?p=440941&viewfull=1#post440941

It is indeed a trivial task to launch a rocket SSTO to Kerbin orbit. But it takes only 4000-4500 delta v, less than half of what you'd need on Eve.

As for the fuel mass - yeah, as I've said you will need at least 5/6 of your craft mass to be fuel even if your average Isp is around 500. Aerospikes alone won't cut it by any means.(dry/full ratio of 1/9 which is impossible with current fuel tanks provided you don't drop them)

Also - I've just managed to leave Kerbin SOI with that thing:

Edit: tried 1 aerospike-1 LV-N combination, turned out it actually is more efficient, gave me around 6000 delta-v easily. Could probably squeeze an extra 1000 dv out of it. Still not enough though.

Edited June 12, 2013 by Jod
For pure awesomeness

[Thunderous Echo]

I was going to say monoprop engines, but because of their isp 5000ish is their theoretical max dv.

Edited October 7, 2014 by Thunderous Echo

[EdFred]

Seriously? This post is over a year old and a handful of releases ago.

[GoSlash27]

Wow, thread necro!

We've worked for the better part of a year looking for an answer to this question.

No, an Eve SSTO (stock parts, stock physics, no debug cheats) does not exist without exploiting glitches.

But if you're cool with exploiting glitches, then yes. Ladder lifters can do the job, and so can infinigliders with kraken drive. We have successful examples of both here

Best,

-Slashy

[Njs41]

I think there was a post awhile ago confirming that an Eve SSTO without abusing infiniglide gliches.

[Thunderous Echo]

Theoretically, what if your landing legs were 100 km tall and massless?

EDIT: I just tried this by editing the .craft file to place a part connected to my ship 100 km below me.

The results were promising until I got attacked by the kraken.

Edited October 7, 2014 by Thunderous Echo

[Jod]

Wow I can't believe this thread is still kicking. So essentially it can be done with exploits, huh... I guess I'll be trying to make a semi-infiniglider with ion engines then.

[Tw1]

Wow I can't believe this thread is still kicking. So essentially it can be done with exploits, huh... I guess I'll be trying to make a semi-infiniglider with ion engines then.

Ion engines? If you're going to exploit glitches, who needs them...

[Jod]

That's... a bit too glitchy for me. I was thinking along the lines of a seat for 1 kerbal, lots of infiniglide flaps since we don't have propellers yet, and some ions for when I'm halfway out of the gravity well.

[sober667]

after 23.5 best way to go is liquid fuel booster i think

[thereaverofdarkness]

Someone needs to invent engines that eat the fuel tank once it's spent, and finally eat themselves and basically use excess structural components as fuel.

[Thunderous Echo]

Well, (assuming no payload) if at the last moment of providing thrust the mass of your craft is zero, that would give your craft infinite delta-v.

In mathematical terms:

As mass -> +infinity

thrust to weight ratio -> +infinity

Therefore, delta-v = infinity

Of course, it would be propelling nothing at infinite velocity, but KSP might still freak out.

[sober667]

Well, (assuming no payload) if at the last moment of providing thrust the mass of your craft is zero, that would give your craft infinite delta-v.

In mathematical terms:

As mass -> +infinity

thrust to weight ratio -> +infinity

Therefore, delta-v = infinity

Of course, it would be propelling nothing at infinite velocity, but KSP might still freak out.

u can make ship within phisicles parts and fly wth infinite fuel

[Fireheart318]

Yeah. Try doing this in 1.1.1. I'm working on an EAV and my game just crashed in the VAB and I'm liquided

Edited April 30, 2016 by Fireheart318
Weird autocorrect thing

[TomPN]

delta-v to Low Eve Orbit (LEO) from sea level: 7500m/s (according to the wiki)

highest atmospheric Isp: 295s (Vector rocket engine)

jet engines don't work on Eve

dV = 7500 Isp = 295 therefore mass ratio = e^(7500/[295*9.81]) = 13.35

You need a dry mass:wet mass ratio of 13.35:1 in order to reach LEO in one stage

The highest mass ratio of fuel tanks in KSP is 9:1

Therefore, SSTO from sea level is not possible on Eve.

[Single stage to ocean]

Possible with stock dlc propellors, get to a point where the dart isp is 315 then light the darts, close the prop in a service bay to reduce drag, go for orbit. Use nuclears and maybe ions if u want to go to gilly 4 refueling.