is an Eve SSTO rocket possible?

[Sereneti]

22 hours ago, Sharpy said:

SSTO from Eve is possible, but it will ONLY be SSTO, nothing more.

Starting on Eve's mountain top with full fuel, reaching Eve low orbit.

No flight from Kerbin. No ISRU on board. No payload. No Gilly. Not landing. Not anywhere on Eve. Possibly not even a Kerbal on board, just a tiny probe core powered from the engine's alternator.

Just hyperedit your craft to the mountain top, and perform the orbital ascent. Proof of concept with no practical meaning.
 

The question was "is an SSTO possible" my answer is Yes.

But it isnt worth it.

(and i mean an Kerbin -> eve -> Kerbin SSTO)

1) no payload only a smal probe.

2) expensive Xeon for the interplanetary flight. (eve-orbit has "better sun" than Kerbin)

3) a big wing to weight ratio, because you can then use a small trust on eve.-> less fuel to go out of the atmosphere

4) aerospike engines dosnt care (much) about the atmosphere densitiy.

....

hm...

i think i make a proof-off concept next week

 

Edited August 18, 2016 by Sereneti

[magnemoe]

1 hour ago, Warzouz said:

The whole purpose of a SSTO (whatever design it has is reusability. Other than that, there is no real meaning for SSTO. When you use a Tylo SSTO lander, as I did back in 0.9, it's because you want to use it multiple times (or recover funds for most of it).

Leaving a platform on Eve will make your ship not a SSTO, because you leave a part. Sure it's not 100% wordy accurate (that' why we have flourishing ridiculous acronyms...). But the concept of SSTO (rocket of space plane is REUSABILITY).

Sure on Kerbin, SSTO only have to take-off and reenter (if reusable, which most of them are). On other planets, they should land and ascent to be qualified as SSTO. In orbit, they would refuel using whatever tug/station/mothership/fuel tank you have designed but that's not part of a SSTO.

And the lander could do it again and again.

Disagreeing a bit here, an Tylo SSTO designed to supply an mining base is an full reuseable ssto even if you need to refuel it both on ground and in orbit for the next run. 
I have an SSTO with build in miner however its large and use forever mining with the small ISRU so an small one with wheels is much more practical
Wheels so I can drive it to the base rather then having an fuel truck, and yes it can only be used at the base, anywhere else and its not an SSTO. 
Same is true for Laythe however here its easier to refuel on ground base or land fully tanked and refuel in orbit again. 
However an Tylo SSTO is not an SSTO if it uses an decent stage Apollo lander style, it was also an single stage lander and accent craft

Now an Eve SSTO is very borderland, just hyperedit something down and get it up in one piece is a major achievement. 
making an practical SSTO is again much harder and none has done it. 

 
 

[KerikBalm]

2 hours ago, Sereneti said:

The question was "is an SSTO possible" my answer is Yes.

But it isnt worth it.

Again.... Prove it. We have exactly 1 example of an SSTO from 1.04.

It had the flimsoest landing gear you've seen. It barely made it, and suffered badly from heat.

Changes since them would make the drag too great, the heating too great, and the landing gear explode before it got off the ground.

Prove it....

[GoSlash27]

3 hours ago, Sereneti said:

The question was "is an SSTO possible" my answer is Yes.

But it isnt worth it.

(and i mean an Kerbin -> eve -> Kerbin SSTO)

1) no payload only a smal probe.

2) expensive Xeon for the interplanetary flight. (eve-orbit has "better sun" than Kerbin)

3) a big wing to weight ratio, because you can then use a small trust on eve.-> less fuel to go out of the atmosphere

4) aerospike engines dosnt care (much) about the atmosphere densitiy.

....

hm...

i think i make a proof-off concept next week

 

I think #3 is the big problem; less thrust does not mean less fuel consumed. It just means more total DV required for the trip due to drag losses.
 

 Good luck, though!

-Slashy

*edit*
 Perhaps you could use a very low t/w and low wing loading to "sail" your way to orbit using LV-Ns? Just hang out at the highest altitude where you can maintain level flight and slowly build speed until you eventually circularize? The heat might prove to be too much, but this might be the only way to SSTO from Eve.

Best,
-Slashy

Edited August 18, 2016 by GoSlash27

[Sharpy]

3 hours ago, Warzouz said:

The whole purpose of a SSTO (whatever design it has is reusability. Other than that, there is no real meaning for SSTO. When you use a Tylo SSTO lander, as I did back in 0.9, it's because you want to use it multiple times (or recover funds for most of it).

Leaving a platform on Eve will make your ship not a SSTO, because you leave a part. Sure it's not 100% wordy accurate (that' why we have flourishing ridiculous acronyms...). But the concept of SSTO (rocket of space plane is REUSABILITY).

Sure on Kerbin, SSTO only have to take-off and reenter (if reusable, which most of them are). On other planets, they should land and ascent to be qualified as SSTO. In orbit, they would refuel using whatever tug/station/mothership/fuel tank you have designed but that's not part of a SSTO.

And the lander could do it again and again.

Oh, but you're building infrastructure!

Next time you land, you don't take any ISRU with you. You just land next to the old one and use it to refuel.

[Sereneti]

41 minutes ago, GoSlash27 said:

I think #3 is the big problem; less thrust does not mean less fuel consumed. It just means more total DV required for the trip due to drag losses.
 

 Good luck, though!

-Slashy

*edit*
 Perhaps you could use a very low t/w and low wing loading to "sail" your way to orbit using LV-Ns? Just hang out at the highest altitude where you can maintain level flight and slowly build speed until you eventually circularize? The heat might prove to be too much, but this might be the only way to SSTO from Eve.

Best,
-Slashy

Yes,"sail" out of the atmosphere and then use a better ISP engine...

ticker Atmosphere means that there is a higer Coffin-corner with less speed.

(afaik: drag area increase the drag linear , speed increase the drag exponential)

moar wing area -> higher  coffin-corner with the same speed.

[KerikBalm]

Ah, so naive...

As if in a week he's going to make an Eve SSTO... oh wait... not an Eve SSTO, but a Craft that goes from kerbin, to eve's surface, and back to kerbin in a single stage....

Quote

Kerbin -> eve -> Kerbin SSTO

Simply not possible

[magnemoe]

2 minutes ago, KerikBalm said:

Ah, so naive...

As if in a week he's going to make an Eve SSTO... oh wait... not an Eve SSTO, but a Craft that goes from kerbin, to eve's surface, and back to kerbin in a single stage....

Simply not possible

With refueling in low Eve orbit the problem is reduced to landing on Eve then taking of and and reaching orbit. 

With mods the rules changes, 
have thought about an Eve lander with an orion nuclear pulse engine,

[Brainlord Mesomorph]

What I was saying in the OP was assuming this mission:

1. Having ISRU perhaps (actually now i know - required to be) on a sistership/tug

2. Kerbin SSTO -> Dock w/ tug go to Minmus, refuel

3. Minmus to Gilly - refuel

4. tug takes lander to LEO - lander lands - 

5  Eve SSTO (actually now i know - to SUBORBIT) dock w/ tug, tug makes orbit

6. back to Gilly - refuel 

and given the 8k dV  that's required for Eve SSTO that also enough for any other LEG of that journey.  Or for ANY leg of ANY SIMILAR trips to ANY of the planets.

That's what I meant by winning KSP.  Those ships could do a JOOL-5 or indeed the KERBOL-17

Edited August 18, 2016 by Brainlord Mesomorph

[KerikBalm]

I can simply mod an engine with 100,000 Isp (atmospheric) and a 100:1 TWR.
So of course, mods are irrelevant for this discussion

If he was allowing refeuling, he wouldn't be mentioning using xenon gas for the interplanetary journey. If he;s talking in the same sense as the OP "without any help, without a fuel tender" then it would have to refuel itself from onboard ISRU... which means it wouldn't just have to make it to eve orbit, but then have enough dV left over to reach eve escape velocity and then some... which is of course not going to happen with the TWRs amd Isps of stock engines, even if stock fuel tanks were massless.

*edit* ok, the OP is now allowing gantries/tugs/staging events (I would count undocking as staging, I think most people would, even if you redock them later). The requirements have simply been reduced to a reusable *system* for which part of the system can land on eve and be returned to eve orbit.

In this case... sure, but its only possible with suborbital rendevous... and even then I have my doubts that this can work for returning from eve sea level.

Also, the suborbital rendevous basically requires automation like mechjeb... manually piloting that is going ot require a lot of quick loads.

Edited August 18, 2016 by KerikBalm

[Terwin]

6 hours ago, Warzouz said:

The whole purpose of a SSTO (whatever design it has is reusability. Other than that, there is no real meaning for SSTO. When you use a Tylo SSTO lander, as I did back in 0.9, it's because you want to use it multiple times (or recover funds for most of it).

Leaving a platform on Eve will make your ship not a SSTO, because you leave a part. Sure it's not 100% wordy accurate (that' why we have flourishing ridiculous acronyms...). But the concept of SSTO (rocket of space plane is REUSABILITY).

Sure on Kerbin, SSTO only have to take-off and reenter (if reusable, which most of them are). On other planets, they should land and ascent to be qualified as SSTO. In orbit, they would refuel using whatever tug/station/mothership/fuel tank you have designed but that's not part of a SSTO.

And the lander could do it again and again.

I can see a lot of purpose to a SSTO that requires surface refueling on Eve/Lathe/Tylo and can deliver base components large enough to include a full mining rig(Drill, ISRU, Probe core, and presumably some sort of mobility and docking/klaw)

You can use it to build surface bases one module at a time.(starting with ISRU of course so you can get back to orbit)

 

On Minmus this is the standard approach for filling orbital fuel bases.(land, fuel up, launch)

[KerikBalm]

+1 to above, surface refeuling is viable

Spoiler

Modular surface base with ISRU:

The mk3 dropship that deployed the modules and can refuel from the surface base:

An almost identical mining module for constructing a similar modular surface base on laythe, with the "dropship" or SSTO being quite different, obviously

 

 

 

- although I went ahead and made some Single Stage to Surface and Orbit /Singlestage to orbit and back (SSTSAO? SSTOAB?) for tylo just for the challenge.

On minmus, I wouldn't say that its "standard" to have a surface fuel station. For me, the dV costs of getting to orbit are so low, that I might as well just take the refinery and drills up too, then I can land anywhere there is ore.

Also... I stopped bothing with an orbital fuel station as well... I just made a massive lander... with twice the capacity of this mun "lander"

Basically, when I launch it, it is a fuel station

[Sharpy]

3 hours ago, GoSlash27 said:

I think #3 is the big problem; less thrust does not mean less fuel consumed. It just means more total DV required for the trip due to drag losses.
 

Less thrust with the same ISp means less fuel consumed per unit of time.

With Eve's thick atmosphere, the terminal velocity is really low, so if you're going fast and thrusting hard, your atmospheric efficiency suffers due to drag losses. So until you're in thinner atmosphere, you must go slow. To go slow you don't need much thrust. You are still losing fuel over the fact the trip up takes so damn long, but you're losing less if you were guzzling fuel just to heat the souposphere and still go only marginally faster.

 

3 hours ago, GoSlash27 said:

 Perhaps you could use a very low t/w and low wing loading to "sail" your way to orbit using LV-Ns? Just hang out at the highest altitude where you can maintain level flight and slowly build speed until you eventually circularize? The heat might prove to be too much, but this might be the only way to SSTO from Eve.

Wing would be a nice idea if it didn't add dead weight later on. If you could discard wings later, that would surely be the way to go, alas - SSTO! Also, in the souposphere you don't need all that much wing area.

Unfortunately, LV-N's thrust down there goes into micronewtons. It won't make your craft even budge, never mind climb. The thrust can be low, but can't be VERY low - You need to move below the terminal velocity, some 50m/s, in a very draggy air. TWR of order of 0.2 should suffice for that, but on LV-N your TWR will be of order of 0.0002.

 

[Brainlord Mesomorph]

2 hours ago, KerikBalm said:

Also, the suborbital rendevous basically requires automation like mechjeb... manually piloting that is going ot require a lot of quick loads.

nonsense! I play a stock game.

the tug needs to be very manueverable and a decent TWR but It's quite doable. I did it the first time I tried it at about 65 km on Kerbin (boy was that exciting!)  But that was a really really good tug. 

Edited August 18, 2016 by Brainlord Mesomorph

[Brainlord Mesomorph]

2 hours ago, KerikBalm said:

ok, the OP is now allowing gantries/tugs/staging events (I would count undocking as staging, I think most people would, even if you redock them later).

I would disagree. Docking (or undocking)  w/ another reusable module in orbit is not the same as dropping a stage and letting it burn up.

and I HAVE learned things in this thread, like the answer to the question " can you build an SSTO, ISRU Eve lander w/ stock parts?" and that is clearly no.

/but we might get close...

Edited August 18, 2016 by Brainlord Mesomorph

[KerikBalm]

The point of staging is that you don't bring everything with you. Undocking and redocking still accomblishes that.

I do lots of fully reusable missions that aren't single stage because I separate parts from the ship. I don't take all parts beyond LKO, I don't take all the parts out of kerbin's SOI, and I don't take all the parts down to the surface.

[foamyesque]

There's that Eve Infinity video that was posted, which is a fully reusable Eve mission, including (necessarily) a single stage to and from Eve's surface without leaving anything there. It had a suborbital rendezvous, though, and also wimped out by using a service-bay protected command seat instead of an actual full-up pod.

 

If you're doing an Eve SSTO you basically have no options other than the Mammoth; it is the best possible engine for the job. I mean, maybe someone could surprise me with something really sweet, but I don't think it's likely. The margins are just too tight to not optimize. You want to use as little wing area as possible -- enough to let you control your reentry and land, then lift off horizontally whilst you climb and build speed before pitching up to head home. From a mountaintop Eve's atmo/gravity ratio is basically the same as Kerbin sea level, so you can actually get a rough idea of what is needed by trying to take off from the KSC. Anything more you carry cuts into your deltaV.

 

The obvious problem with a SSTO is basically that while you need a Mammoth to drive you out of the lower atmo with a full fuel load it's an awful lot of engine to carry all the way up. Adding secondary, high Isp engines for high-altitude use simply makes the problem worse, because then you need even more engine through the critical phase, which means you have even more dead weight higher up. The mass ratio just murders you.

 

 

[Kergarin]

Is there a higher "landable" mountain than ~6.000m on eve? 

My best so far is 2900m/s at 90km ap started from 5.800m. 

[GoSlash27]

6 hours ago, Sharpy said:

Less thrust with the same ISp means less fuel consumed per unit of time.

With Eve's thick atmosphere, the terminal velocity is really low, so if you're going fast and thrusting hard, your atmospheric efficiency suffers due to drag losses. So until you're in thinner atmosphere, you must go slow. To go slow you don't need much thrust. You are still losing fuel over the fact the trip up takes so damn long, but you're losing less if you were guzzling fuel just to heat the souposphere and still go only marginally faster.

Sharpy,

Well... *sorta*. Fuel is consumed at a lower rate with lower thrust, but over a longer period of time due to the reduced acceleration. You wind up spending a lot more time in atmosphere and suffer more DV loss to drag than you would otherwise.

6 hours ago, Sharpy said:

Wing would be a nice idea if it didn't add dead weight later on.

 Actually, this isn't much of a problem. Wings comprise a very low percentage of the total mass of airplanes in KSP. Moreover, wet wings are the lowest- drag way to carry your fuel. Minimizing drag is absolutely critical if you're going to try to fly out of Eve.

Best,
-Slashy

[foamyesque]

1 minute ago, GoSlash27 said:

 Actually, this isn't much of a problem. Wings comprise a very low percentage of the total mass of airplanes in KSP. Moreover, wet wings are the lowest- drag way to carry your fuel. Minimizing drag is absolutely critical if you're going to try to fly out of Eve.

Best,
-Slashy

Wet wings get you nowhere on Eve, since you can use neither airbreathers nor nukes, and carry an absolute pittance of fuel in any case. As such you're going to be using 3.75m/Mk3 rocket fuel tanks regardless-- and the dead mass of those wings is very relevant.

[GoSlash27]

Just now, foamyesque said:

Wet wings get you nowhere on Eve, since you can use neither airbreathers nor nukes, and carry an absolute pittance of fuel in any case. As such you're going to be using 3.75m/Mk3 rocket fuel tanks regardless-- and the dead mass of those wings is very relevant.

foamyesque,

 If he's going to try to use LV-Ns at higher altitude for the brunt of the work, he's gonna need to store jet fuel. There's no better way to do that with wet wings, especially if he's looking for low wing loading.

 I'm not sayin' it's gonna work, mind you... but if that's what he's trying to do, that's probably his best chance of success.

Best,
-Slashy

[foamyesque]

3 minutes ago, GoSlash27 said:

foamyesque,

 If he's going to try to use LV-Ns at higher altitude for the brunt of the work, he's gonna need to store jet fuel. There's no better way to do that with wet wings, especially if he's looking for low wing loading.

 I'm not sayin' it's gonna work, mind you... but if that's what he's trying to do, that's probably his best chance of success.

Best,
-Slashy

 

I'm saying it won't, though. The only way to success is to simplify: Cut weight everywhere and anywhere (smallest possible landing gear, seat+servicebay "pod", etc), use a Mammoth, get the smallest possible amount of lift (and consequently induced drag), etc.

[GoSlash27]

I would argue that there isn't *any* way to success on this project. The math says that using a Mammoth (even with zero drag) will yield *at best* 6,790 m/sec DV. That's with an infinite number of fuel tanks, no mass that's not fuel tanks, and vacuum ISP.

It's nowhere near enough.

If he has any chance at all of making orbit from sea level in a single stage, he'll have to use nukes or ions in the process.

*edit* Of course... this is assuming he doesn't get cheaty as heck.

http://s52.photobucket.com/user/GoSlash27/slideshow/KSP/KrakBadger

 

Best,
-Slashy

 

 

Edited August 18, 2016 by GoSlash27

[KerikBalm]

6 hours ago, Brainlord Mesomorph said:

nonsense! I play a stock game.

the tug needs to be very manueverable and a decent TWR but It's quite doable. I did it the first time I tried it at about 65 km on Kerbin (boy was that exciting!)  But that was a really really good tug. 

Well, I was specifically referring to Eve. Obvioust suborbital rendezvous is more or less diffucult based on the circumstances. Its super easy on Gilly, for example.

Eve is another story. If taking off from its highest mountain, you've got to deal with an inclined orbit, which makes the timing more difficult. You've got less margins on the tug, less margins on the ascent vehicle. Timing of the launch would be crucial.

If you do it from eve sea level... well then its easier to time the launch, and there's 1 launch window for every orbit of the tug, but now the dV and TWR required of the tug is even higher, and the ascent vehicle's "hang time" near apoapsis will be even lower.

Sure, its doable, but as I said, lots of quick saves/loads needed.... and its quite different from what was described at the start of this thread and not at all SSTO.

Also, Jool's lower atmosphere would still be quite out of reach except for 1 way probe/suicide missions

[foamyesque]

16 minutes ago, GoSlash27 said:

I would argue that there isn't *any* way to success on this project. The math says that using a Mammoth (even with zero drag) will yield *at best* 6,790 m/sec DV. That's with an infinite number of fuel tanks, no mass that's not fuel tanks, and vacuum ISP.

It's nowhere near enough.

 

Well, no, not from sea level, not in one shot. It might be possible to cart an integral ISRU unit to space so you can do a chain of sea-level -> mountaintop -> space, but you'd need a truly monstrous rocket to make it happen. The deltaV from a 6500m+ mountaintop is, IIRC, 5500m/s or so, which is just within a Mammoth's reach.