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SSTO on Eve: is it possible?


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this is a theoretical/challenge question. I would like to have a mothership that can drop a rover on eve and recover it in a completely reusable fashion; that would of course require that the rover be packed up into a cargo bay of a rocket that can SSTO on EVE.

according to my deltaV map, landing-taking off from eve costs 8000 m/s. a giant tank with a mammuth engine will have 6000 m/s of deltaV. make it 5000, because i will have a payload: that rover must carry at least a convert-o-tron and drill, plus wheels and science instruments. plus the cargo bay, which is not weightless. it seems we are missing 3000 m/s.

then again, perhaps 8000 for eve is not the most optimized. the same map gives 3400 for kerbin, but i have seen vehicles get a kerbin orbit with as low as 2700 m/s. also, getting on a suborbital trajectory where i could send in a fast tanker for a refueling would also be acceptable. it would be a difficult manuever, the launch would have to be timed right for an intercept in the few minutes you get out of the atmosphere, and the intercept velocity could be as high as 1 km/s, so the tanker would have to be optimized for the task. but it's ok, if i need a bit of extra speed to finish circularizing the orbit i can do that. finally, perhaps there are ways to use eve's atmosphere to help. maybe an helicopter can lift the rocket for the first few kilometers, or maybe good aerodinamics will allow a more optimized trajectory.

anyway, are you aware of anyone managing an eve ssto? would it be feasible to try to build one, or would it just be a waste of time?

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There are some extremely cool Breaking Ground Eve SSTOs out there. They use propeller power to get out of the lower atmosphere, then rocket to orbit.

I've never built an eve SSTO but have built a fully recoverable two-stage rocket/glider Eve launch system (lifter goes suborbital, orbiter flies to orbit, switch back to lifter and glide it back down before it disappears), and a helicopter/rocket/glider one (helicopter flies to the upper atmosphere, rockets into a suborbital parabola, orbiter flies to orbit, switch back to lifter, autorotate down). The former even ships with a service craft that will recover the orbiter, reassemble, and refuel the craft.

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https://kerbalx.com/Brikoleur/BAK-9011-Raphael

https://kerbalx.com/Brikoleur/BAK-9012-Elvira-L

https://kerbalx.com/Brikoleur/BAK-9900-Seraph

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16 hours ago, king of nowhere said:

then again, perhaps 8000 for eve is not the most optimized. the same map gives 3400 for kerbin, but i have seen vehicles get a kerbin orbit with as low as 2700 m/s.

Delta-V map refers to vacuum Delta-V.  Make sure you use the same reference for consistency. 

 

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Two things:

1. SSTOs are not really practical for Eve. They are so borderline that they are usually impractical for anything other than bragging rights. 

2. dV figures for surface to orbit on Eve are mostly useless. You can build a massive craft with much more than the listed dV required that will never make orbit due to the very high drag of every part in Eve's atmosphere. Plus the poor isp of most engines there means achieving the listed dV is even harder. 

Your best bet will remain using a more conventional rocket and abandoning everything but the crew on the surface. 

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3 hours ago, Foxster said:

Two things:

1. SSTOs are not really practical for Eve. They are so borderline that they are usually impractical for anything other than bragging rights. 

 

EVERYTHING in this game past the first few weeks is only about bragging rights.

i unlocked the full tech tree without ever going out of kerbin SoI. I could have done it without ever getting past kerbin orbit, if i had wanted to abuse the mobile laboratory and wait a lot of game time.

money is virtually unlimited. tourist contracts generally yield ten times what i spend on the rocket.

I already have ships that can go everywhere on the solar system, except on eve and laythe. and getting to eve and back is just a matter of reopening one of my old lunar landers and add a first stage that works well in atmosphere, plus scaling up the launcher. i am latching to this additional challenge, when i will run out of challenges i will likely stop playing the game

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4 minutes ago, VoidSquid said:

What do you want then? A game that sets the goals for you, telling you do this, do that?

Or freedom of choice, set your own goals?

no, i'm just saying that i don't care that it is impractical, because i'm past the point where i do things for practicality

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28 minutes ago, king of nowhere said:

no, i'm just saying that i don't care that it is impractical, because i'm past the point where i do things for practicality

You can always boost the difficulty level of the game. ;)

Every time you drop the contract rewards for science and funds by 10%, it gets a lot harder.

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1 hour ago, king of nowhere said:

EVERYTHING in this game past the first few weeks is only about bragging rights.

My point is not whether it's possible but whether it's useful. 

The OP wanted to do some stuff on the surface of Eve and return. For that there are better option than an SSTO

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2 hours ago, Foxster said:

The OP wanted to do some stuff on the surface of Eve and return. For that there are better option than an SSTO

i am the OP, and what i want is to have a large orbiting ship dropping a rover on the surface of Eve and then picking it up, and being able to do it again and again. this requires SSTO.

but regardless of this  exxcuse of a reason, basically i just want to try it. at least, if i can manage to understand how to control helicopters, since i think the first part of the ascent will use one

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Just now, king of nowhere said:

i am the OP, and what i want is to have a large orbiting ship dropping a rover on the surface of Eve and then picking it up, and being able to do it again and again. this requires SSTO.

but regardless of this  exxcuse of a reason, basically i just want to try it. at least, if i can manage to understand how to control helicopters, since i think the first part of the ascent will use one

I think you are going to struggle. It's barely possible to have a no-payload SSTO make orbit and even then its difficult. It's hard to imagine doing it with a useful-sized payload of a rover and, presumably, mining gear. 

If you want a rover to visit several locations then it might be worth considering a mining-refueling rocket plane doing hops. The last leg back to orbit with the science/crew could be done with another small rocket either carried too or else dropped to rendezvous on the surface. 

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1 hour ago, Foxster said:

I think you are going to struggle. It's barely possible to have a no-payload SSTO make orbit and even then its difficult. It's hard to imagine doing it with a useful-sized payload of a rover and, presumably, mining gear. 

If you want a rover to visit several locations then it might be worth considering a mining-refueling rocket plane doing hops. The last leg back to orbit with the science/crew could be done with another small rocket either carried too or else dropped to rendezvous on the surface. 

i have seen some SSTO using helicopter rotors to lift past the heaviest part of the atmosphere. that's a huge advantage because it skips the worst aerodinamic and rocket efficiency problems. once in high atmosphere, it should be relatively easy to get to orbit. orbital speed around eve is a bit over 3000 m/s, most of the 8000 required in the deltaV map is overcoming the atmosphere. i should make it with 4000 m/s.

i will have some 7 tons of mining equipment and perhaps 5 tons of rover (i could do it smaller, but i want to build all my rover with a cupola seat to drive them in first person). with 12 tons payload, i should have the desired deltaV with an 80-ton rocket.

the problem is making a helicopter to lift a 80-ton rocket. i have yet to figure out how to control an helicopter

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50 minutes ago, king of nowhere said:

i have seen some SSTO using helicopter rotors to lift past the heaviest part of the atmosphere. that's a huge advantage because it skips the worst aerodinamic and rocket efficiency problems. once in high atmosphere, it should be relatively easy to get to orbit. orbital speed around eve is a bit over 3000 m/s, most of the 8000 required in the deltaV map is overcoming the atmosphere. i should make it with 4000 m/s.

i will have some 7 tons of mining equipment and perhaps 5 tons of rover (i could do it smaller, but i want to build all my rover with a cupola seat to drive them in first person). with 12 tons payload, i should have the desired deltaV with an 80-ton rocket.

the problem is making a helicopter to lift a 80-ton rocket. i have yet to figure out how to control an helicopter

Well, good luck. Do post your craft here when you get it working. 

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