RocketBlam

So what does it take to get off of Eve these days?

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16 minutes ago, Xyphos said:

Eve has a very dense atmosphere, rockets tend to loose effectiveness...

Thanks, and well versed in the fact that elevation of the landing site matters, I was curious as to what degree. I was guesstimating somewhere in the 1-2km/s range for dV loss?

Edit: Should note that in my head a number of 4km elevation (IIRC from earlier discussions) pops up for optimal(ish) landing sites

Edited by Glaran K'erman

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yeah, it's about 150 dV lost, for every km or so. rough guestimation.
but, imagine if your rocket was lifted to 10km by an octo-copter, or your spaceplane flew that high with wings and a fan;
the dV lost to the atmosphere would be gained in terms of lift, where rockets become better suited, then dV isn't much of an issue.
the idea is almost as crazy as dropping a rapier-powered vessel from a big balloon at high altitudes :P

Edited by Xyphos

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In 1.0.4 I got to orbit with about 500m/s left in the tank using this:

OfASWwg.png

The vessel was built and fueled on the surface using Extraplanetary Launchpads.

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16 minutes ago, Mitchz95 said:

In 1.0.4 I got to orbit with about 500m/s left in the tank using this:

OfASWwg.png

The vessel was built and fueled on the surface using Extraplanetary Launchpads.

Is that 4 aerospikes in the middle there, under a 2.5m tank?

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On 5/4/2016 at 11:44 AM, Foxster said:

For interest, here's sea-level-capable 1.1 Eve lander weighing a tad over 40t...

FkWHKPx.jpg

A lot of this went into my first (and likely only) Eve lifter. It doesn't quite make Sea Level but from 2km or higher it can reach orbit. Landing and launching yours (and following your instructions both for your own and mine) really helped a lot. Thanks!

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there are engines they use the air around as Working-Mass.
The Energy for that comes from Fuel+Oxidicer...

They work like a normal jet-engine, but in the combustion-chamber burn a mixture of Oxidicer and Fuel...

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I see there's a mod now called something like Engines for Eve. Might be worth checking it out if you don't mind modded parts. 

Edited by Foxster

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Here's my lander.  Pretty sure it will work.  Just the raw design, no batteries ,chutes, etc.  Gonna have to fuel it on eve with an ISRU.

Its kinda big.

https://www.dropbox.com/s/kmvzbeeiqpc28dr/Eve%20Lander.craft?dl=0

Hope the link works, I'm new to this.

Edited by CheckYoStaging

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22 hours ago, 5thHorseman said:

Is that 4 aerospikes in the middle there, under a 2.5m tank?

Yes. It's an asparagus launcher, so all twelve main engines ignite at launch and eventually are whittled down to the four core engines. Finally the orbiter with the two Kerbal passengers separates and makes the final orbital insertion, with plenty of fuel left for orbital rendezvous.

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Hi guys

I landed to Eve in 1.0.5 with this big Atomic plane, able to escape to orbit by launching its rocket front part at 14km altitude. This plane is also able to fly all around Eve. I need Adjustable landing gear to be updated to do it in 1.1.2 with the new inflatable shield. I think the de orbiting mass will be much lower!

But how do you aerobrake when arriving in Eve SOI. I had to protect my de orbiting rocket with a removable shield and I was not able to set the Peri below 83 kms at the first passage, (below the whole thing would explode) and I burnt retrograde to set the Apo at 10.000kms then I aerobrake with a 79-80km peri during to many orbit tour...!I tooks very long time...

951545screenshot481.png

Launch De-orbit and landing

http://forum.kerbalspaceprogram.com/index.php?/topic/138186-a-plane-to-land-explore-and-escape-from-eve/

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38 minutes ago, gilflo said:

But how do you aerobrake when arriving in Eve SOI.

I don't. I suck it up and bring the fuel to slow down manually.

And nice plane!

Edited by 5thHorseman

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On ‎5‎/‎6‎/‎2016 at 11:35 AM, Foxster said:

I see there's a mod now called something like Engines for Eve. Might be worth checking it out if you don't mind modded parts. 

 

It provides low expansion ratio variants of some of the game's stock engines to provide better performance on Eve.  It is based on real life science and engineering.


It's been some time since I last performed a full-up landing and return from Eve, though I did use Hyperedit to run some launch experiments in KSP 1.0.5 (KSP 1.1.2 should be no different).  Using Eve's stock engines, I found that I could get to orbit from sea level with a Δv of about 7000 m/s, though that was cutting it pretty close.  I'd probably design for at least 7500 m/s to play it safe, plus whatever you might need after reaching orbit (e.g. for rendezvous).
 

Edited by OhioBob

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This lifter was posted on reddit by /u/MarcusIuniusBrutus.

6JGa9DS.jpg

Its only shortcoming, he notes, is that is light on parachutes, only able to safely land at terrain <1000m ASL altitude. He also notes that it packs just shy of 7900 dV after ladders, science, and legs have been jettisoned. It reached orbit from 500m altitude with 300-500m/s of dV margin. Also, here is his full album.

Edited by Captain Sierra

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On 4/5/2016 at 11:44 PM, Foxster said:

For interest, here's sea-level-capable 1.1 Eve lander weighing a tad over 40t...

If anyone fancies trying it then the flight is something like...

 

Tested, works perfectly, landed about 1000m over sea level. Launched with GT 26km, orbit 105km, 40% shape, 100km end GT, 700ms dV available. Will try modifications to recover 100% science :)

Thanks for the cool design!! :)

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4 hours ago, JorgeCS said:

Tested, works perfectly, landed about 1000m over sea level. Launched with GT 26km, orbit 105km, 40% shape, 100km end GT, 700ms dV available. Will try modifications to recover 100% science :)

Thanks for the cool design!! :)

You are welcome. 

I'd think you could just pop the sciency stuff on the bottom and decouple before launch or on the drop-tanks.

Though my fav way to dump stuff like this is with an escape thingy...oh, you know...whatever it's called. 

Edited by Foxster

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On 5/6/2016 at 3:33 AM, LameLefty said:

 Let's be clear on terminology - "compression" of the air per se is not required for thrust. What IS required is MOVING the air, which is basically what a propellor does in an ordinary general aviation aircraft on earth. The thrust on a Cessna, for instance, is because of the mass of hair being pushed backward by the prop. Yes, there is some localized compression of the high-pressure air behind the prop blades pushing forwards, but there is an equal rarefaction (lowering of the pressure) of the air flowing across the top of the blades; the thrust is simply F=ma.

The only time you need or even really WANT compression of your reaction mass is in the case of a combustion process, where adding compression and then injecting fuel into the compressed air for combustion causes rapid expansion (and again, MOVING the air).  But if you're not using that air for combustion, compressing it is a waste of energy. Just move the air with a fan.

(DISCLAIMER: I am an actual aerospace engineer by education and former profession; this subject is pretty basic propulsion engineering but without knowing the background of the audience, it's hard to know how much detail to go into).

Well since the primary question of how much dV is needed has been answered.

What we're talking about here are a few concepts.

One is just a propellor or fan, that gets its energy from combustion of stored fuel and oxidizer... it could be a "hybrid" with the fan being moved by an electric motor, and then a fuel cell or a generator burning LFO supplies the electricity.

Then there's the "Ramrocket" or "air augmented rocket" that is basically a ramjet with oxidizer supplied by internal stores. The heat from combusion of the LFO is used to expand the atmospheric gasses, producing thrust just as in a ramjet.

This can be made to work with a turbine as well. where expansion of the heated gasses drives a turbine to pull in more atmosphere.

You would likely still want to compress the atmosphere in the combustion chamber to have a larger mass of air in the combustion chamber to mix with the hot LFO combustion products. Again, the heated airmass expands producing thrust.

It works exactly the same as a jet engine, except now you need to supply fuel and oxidizer, so effective Isp is reduced... effective Isp is still better than a chemical rocket because of the "free" reaction mass.

Because KE= 1/2 mv^2

For the energy it takes to expel 1 kg of reaction mass at 4000 m/s (ie a chemical rocket with an Isp of about 400), you could expel 4kg of reaction mass at 2000 m/s, which produces twice as much thrust (assuming 100% efficiency, using 3kg of "air" and 1kg of "LFO", you've increased your Isp from 400 to 800).

"Fuel" and propellant aren't the same thing. Fuel supplies the energy, propellant is the reaction mass. In a nuclear-ion drive system, U-235 would be the fuel, and Xenon gas would be the propellant.

In a chemical rocket, the fuel and propellant are basically the same thing, as the "energy storage medium" (ie, the chemical fuel and oxidizer) is also  the reaction mass.

It doesn't have to be this way, and you can have an air-augmented engine that takes in additional working mass, such that the fuel+oxidzer mix does not form the primary reaction mass but is the sole energy source.

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thanks guys and girls, this thread helped me get off eve! The beast has been slain! (in what did you do in ksp today thread)

My craft had 8000dv and a TWR at sea level of 1.15 (but got back from 3000)

life support mods meant more weight

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On 5/5/2016 at 9:57 PM, Xyphos said:

Eve has a very dense atmosphere, rockets tend to loose effectiveness in atmospheric conditions due to the pressure pushing back on the thrust.
this causes the rocket to loose both thrust and ISP (the efficiency measurement)
Although possible to return to Eve's orbit from sea-level using rockets, it's definitely not efficient or practical,
which is why I suggest a new engine type, rocket powered fans (or even helicopter rotors)
to bring the vessel up to an altitude where rockets would be better suited.

DISCLAIMER: I do not claim to be an aerospace engineer, I'm just a guy who likes to tinker with things, and play sandbox games.

So what we really need then are just helicopter rotors in the game lol. Which I think someone already made in a mod somewhere.

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Here is my lander for 2 kernels, tested to reach Eve orbit from 350m take off altitude.

231301screenshot236.png

485076screenshot252.png

 

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Delta V is difficult to estimate on ground or in VAB.

USING KER, It is not 8000DV in VAB with EVE setting. Mine shows 4300-4500DV. DV is increasing when tou climb. It's more a matter of mixing  TWR and DV to reach 15kms with around 4000DV left and enough TWR for acceleration.

it's also very important to build a ship as dragless as possible.

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I really like the idea of the 'helicopter'

I think its Fire spitter mod that added rotor blades, one type is even foldable so could be ok on the Eve descent.

There are electric and fuel powered options, and using tweakscale you can adjust them for optimum TWR.

There is definitely some investigation to be done here. If i get time, I'll have a go at this at the weekend.

(never been to Eve, not even a flyby!)

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From sea level, for a first timer (8000 Dv)

Although when it comes to eve, it's all about aerodynamics and TWR. You can do it with 7000m/s.
Or even 5500m/s from the highest point.

You can cut that atmosphere like a knife through butter, or with a blunt hammer. The latter method consumes more Delta V.

You can do it for just 5300m/s from the mountain top with this which has 5515 M/s Dv

ifcTH5J.jpg

Notice the vector engine in the middle, giving it ridiculous TWR of the ground, the Intakes on the radial tanks are very aerodynamic, and it accelerates on Eve in a way that looks like there is little to no air resistance.

Edited by Vaporized Steel

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From what altitude can reach Eve orbit with this small lander?

And what are the engines on stage 1 and 0?

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