Eve SSTO: any possible ways?

[foamyesque]

On 2017-01-08 at 2:25 PM, GoSlash27 said:

Der Anfang,

 More to the point, if your craft can only land in one place, there's not much point in making it SSTO.

Best,
-Slashy

If it's refuel-capable you can land anywhere there's ore, and then go to your launch site.

[GoSlash27]

33 minutes ago, foamyesque said:

If it's refuel-capable you can land anywhere there's ore, and then go to your launch site.

foamyesque,

 Maybe, maybe not. It all depends on what you're using for propulsion and your t/w for the final push to orbit. Going down to sea level means that even if you have suitable engines, they may not produce the thrust and DV needed to get you to a safe landing on a mountain. Even the act of getting from the foothills to a peak safely eats up a lot of DV. Eve doesn't make life easy on our intrepid kerbonauts.

Best,
-Slashy

[foamyesque]

1 minute ago, GoSlash27 said:

foamyesque,

 Maybe, maybe not. It all depends on what you're using for propulsion and your t/w for the final push to orbit. Going down to sea level means that even if you have suitable engines, they may not produce the thrust and DV needed to get you to a safe landing on a mountain. Even the act of getting from the foothills to a peak safely eats up a lot of DV. Eve doesn't make life easy on our intrepid kerbonauts.

Best,
-Slashy

I'm reasonably sure anything built to SSTO from Eve -- even from a mountaintop -- is going to be able to achieve a takeoff and hop at lower altitudes. If not when fully fuelled, then at a partial fuel load.

[GoSlash27]

Just now, foamyesque said:

I'm reasonably sure anything built to SSTO from Eve -- even from a mountaintop -- is going to be able to achieve a takeoff and hop at lower altitudes. If not when fully fuelled, then at a partial fuel load.

 foamyesque,

 That might be a proposition worth checking out, but from *my* design philosophy that would not be the case. Any launcher I design for minimum cost and mass will have a launch t/w of 1.4 or less. If that's all it can do from 2 atmospheres, there's no way it can lift off at 5. I'm not even sure it's possible to make an SSTO with that t/w that can still SSTO and I'm not sure that even if I could do that that the DV from down there would be sufficient to climb a mountain. But again... it's a proposition worth checking out.

Best,
-Slashy

[foamyesque]

3 minutes ago, GoSlash27 said:

 foamyesque,

 That might be a proposition worth checking out, but from *my* design philosophy that would not be the case. Any launcher I design for minimum cost and mass will have a launch t/w of 1.4 or less. If that's all it can do from 2 atmospheres, there's no way it can lift off at 5. I'm not even sure it's possible to make an SSTO with that t/w that can still SSTO and I'm not sure that even if I could do that that the DV from down there would be sufficient to climb a mountain. But again... it's a proposition worth checking out.

Best,
-Slashy

Sure it can. Eve SSTOs approach the wet:dry ratio of naked tanks; just don't fill it all the way and you can execute a vertical takeoff ASL.

[Leafbaron]

what we need for Eve is a scramjet type engine, that generates static charge from the thick atmosphere to power lasers to break the co2 into c and o2, the o2 then can be used to ignite the ethane in the atmosphere. Electric jet propulsion on eve! of course you'd still need chemical rockets to achieve the speeds to get the scramjet fired up. 

[GoSlash27]

20 minutes ago, foamyesque said:

Sure it can. Eve SSTOs approach the wet:dry ratio of naked tanks; just don't fill it all the way and you can execute a vertical takeoff ASL.

Yes... at the expense of dramatically reducing your DV to the point where you can no longer reach the top of the mountain. The high pressure at Eve sea level is a double whammy.

As a quick and crude demonstration, say your thrust is reduced to 2/5 the value at sea level, so you have to reduce fuel to 2/5 the former value. That drops your DV from 7 km/sec to 3 km/sec at the original Isp, but remember that the Isp has also dropped to 2/5 the original value. Now you're looking at 1,200 m/sec and you're going to have a hard time climbing a mountain. That's not even counting the huge drag encountered along the way...

 I'm interested in seeing this proposition tested, but I don't think it will be nearly as easy to accomplish as you assume.

Best,
-Slashy

 

15 minutes ago, Leafbaron said:

what we need for Eve is a scramjet type engine, that generates static charge from the thick atmosphere to power lasers to break the co2 into c and o2, the o2 then can be used to ignite the ethane in the atmosphere. Electric jet propulsion on eve! of course you'd still need chemical rockets to achieve the speeds to get the scramjet fired up. 

Leafbaron,

 I think the point of Eve is that it's supposed to be ridiculously difficult. Sort of a Kerbal Kobayashi Maru. We can operate from Eve, but it's very difficult.

Best,
-Slashy

Edited January 11, 2017 by GoSlash27

[foamyesque]

I've done a lot of flying on Eve -- though, granted, not SSTOs. The reduced Isp ASL is murderous, yes, but it's possible to daisy-chain your way around the world and it's readily possible to hit 7km from sea level in a single stage.

[GoSlash27]

24 minutes ago, foamyesque said:

I've done a lot of flying on Eve -- though, granted, not SSTOs. The reduced Isp ASL is murderous, yes, but it's possible to daisy-chain your way around the world and it's readily possible to hit 7km from sea level in a single stage.

foamyesque.

 I'm sure. But doing it in an SSTO capable ship? That's a whole 'nother thing. I'm gonna have to see that one.

Good luck,
-Slashy

 

[gilflo]

Here is what i did in 1.1.2

As it is not possible to SSTO from Eve, i design a plane, able to survive atmospheric descent to Eve and then land, explore Eve without mining nor refuelling, and allow the cockpit to join a shuttle waiting in orbit at 110kms.

This plane was launched from Kerbin using rockets and bring to Eve by rockets, then it was on its own.

From descent to Eve exploration, it's a plane. On  its final climb to reach Eve orbit it's a plane launching a rocket in flight...

..It is a modded plane and here is the story.

 

 

 

Edited January 11, 2017 by gilflo

[KerikBalm]

The problem with a refueling craft is that it absolutely relies on the ore (which is pseudo-randomly generated for each save) being present at the highest peak (s?) on Eve.

If you have ore present at the 7km+ peak on eve, you can hope ot other areas with ore, and even a little bit awaty from them and return to an area with ore... and then hop back to the peak and refuel from that ore.

If there is no ore present at the 7km+ peak, its over for you, for practical purposes... unless.... you send down a massive fuel truck, and you can set up a mining base within drivign distance: then you could hop your craft back to the launch site, and drive your big honking fuel truck up the mountain to refuel the rocket.

For practical purposes, wheels are the only thing that allow you to move around with just electric charge in stock.

Those stock electric props, as far as I know, rely on splitting the craft into two parts and using reaction wheel craft to turn the prop, which will push/pull the associated craft along a "stock bearing" while physics simulations are going on. I'm pretty sure that they fall apart once placed on rails - so not usable. in this context

[Sharpy]

One approach I'm planning:

A permanent floating base, with large ISRU, efficient drills, and all necessary infrastructure. It can fly up to well over 20km altitude, where all engines work at >90% vacuum ISp. And it can move all over Eve using electric propellers, so essentially, for free. Serving as a high-altitude launchpad, it can deliver payloads and kerbals to Eve orbit quite easily.

One thing I gave up on is reusable SSTO. The one huge challenge would be recovering it and packing it onto the base's deck. Instead, the lander will be ground up into scrap metal, which will then be converted into a dedicated launch vehicle using extraplanetary launchpads - the requirements for launch are considerably different from these for landing on Eve, packing both into the same vehicle would be quite inefficient - so landers launched from Gilly are remade into launchers on Eve, launched back to Gilly and remade into landers again.

[Marzl]

10 hours ago, Leafbaron said:

what we need for Eve is a scramjet type engine, that generates static charge from the thick atmosphere to power lasers to break the co2 into c and o2, the o2 then can be used to ignite the ethane in the atmosphere. Electric jet propulsion on eve! of course you'd still need chemical rockets to achieve the speeds to get the scramjet fired up. 

Basically that exactly is what I did in my mod. I use an intake and lot of electricity to split co2 to o2, with that you are able to use all jet engines on eve (and duna) then.

I was not able to do a release due to missing time, but may be next week I will be able to. But it is already working as designed

[cantab]

I doubt "stock propellers" are going to be workable because of the mass and drag penalty they'll cause. It'll be fine when you're just pootling up on the propeller, but once you light the rockets that drag is going to bite. Maybe if you can squeeze a working prop into a cargo or service bay you might have something, but that's a tall order too and doesn't address the mass. And a carrier aircraft is reusable in theory but not in practice without mods because the plane will get deleted, not to mention the challenge of integrating a plane and a rocket on the surface of Eve, something that's hard enough on Kerbin.

The tried and tested way is to drive to the top of a mountain of course.

As for doing it without ISRU, well then your challenge is landing. I believe players have found it rather hard to enter Eve's atmosphere with a full fuel load and survive. And any extra mass used to help that re-entry is then cutting into your SSTOness, unless you're happy to ditch your heatshields.

[Foxster]

It's not going to happen in any practical sense for stock. No bad thing, Eve is supposed to be hard. 

Having said that, Eve is now probably the easiest it has ever been for rockets. You can get a manned rocket to orbit from sea level massing less than 20t at liftoff. Kinda makes messing about with massive and impractical SSTOs on mountain tops a tad pointless.  

Edited January 11, 2017 by Foxster

[fourfa]

just a heads-up, it is possible to take your separate craft in a stock propeller bearing, and reintegrate them into one ship before timewarping (with shielded docking ports or the Claw)

edit: shielded docking ports don't have enough throw to get more than a meter away to let the magnets re-engage.  Has to be the claw unless you have a more complicated mechanism that moves further.

Edited January 29, 2017 by fourfa

[GoSlash27]

58 minutes ago, Foxster said:

It's not going to happen in any practical sense for stock. No bad thing, Eve is supposed to be hard. 

Having said that, Eve is now probably the easiest it has ever been for rockets. You can get a manned rocket to orbit from sea level massing less than 20t at liftoff. Kinda makes messing about with massive and impractical SSTOs on mountain tops a tad pointless.  

Foxster,

 I agree. The entire point of SSTOs is that they can be reused indefinitely simply by refueling. If you're going to build a ship that can only launch from one place, then there's no practical reason to do it multiple times. SSTOs are heavier and bulkier than their staged counterparts, and that comes with a steep price tag.

 OTOH, people do a lot of things in this game for reasons other than practicality.

 Best,
-Slashy

[foamyesque]

9 hours ago, KerikBalm said:

The problem with a refueling craft is that it absolutely relies on the ore (which is pseudo-randomly generated for each save) being present at the highest peak (s?) on Eve.

That's true, but the vast majority of Eve has at least some ore, excluding the ocean biome. You'd want to take the big drill to ensure you can refuel wherever any ore at all exists, though.

 

18 hours ago, GoSlash27 said:

foamyesque.

 I'm sure. But doing it in an SSTO capable ship? That's a whole 'nother thing. I'm gonna have to see that one.

Good luck,
-Slashy

 

KER claims a replica of @Kergarin's smaller SSTO vehicle (posted on page 1) would have a TWR of 0.87 and a dV of 3144m/s at 0 altitude on Eve; at 1km that goes to 0.92 and 3291m/s. With fuel removed to achieve a TWR of 1, at 1km, you get 3122m/s dV. That's sufficient.

Edited January 11, 2017 by foamyesque

[GoSlash27]

55 minutes ago, foamyesque said:

KER claims a replica of @Kergarin's smaller SSTO vehicle (posted on page 1) would have a TWR of 0.87 and a dV of 3144m/s at 0 altitude on Eve; at 1km that goes to 0.92 and 3291m/s. With fuel removed to achieve a TWR of 1, at 1km, you get 3122m/s dV. That's sufficient.

foamyesque,

 If you say so *shrug*. I used to have an SSTO flying car back in an early version. I could fly it to the island runway with that much DV, but that was about it. Wouldn't have a really good feeling about landing it on top of a mountain, and it was designed for that sort of thing.

 Biome hopping Eve in a design like that may be *possible* (I really don't know), but I'm *sure* it wouldn't be safe or easy. I definitely would not plan a mission around such a notion, but YMMV.

Best,
-Slashy

[foamyesque]

Just now, GoSlash27 said:

foamyesque,

 If you say so *shrug*. I used to have an SSTO flying car back in an early version. I could fly it to the island runway with that much DV, but that was about it. Wouldn't have a really good feeling about landing it on top of a mountain, and it was designed for that sort of thing.

 Biome hopping Eve in a design like that may be *possible* (I really don't know), but I'm *sure* it wouldn't be safe or easy. I definitely would not plan a mission around such a notion, but YMMV.

Best,
-Slashy

 

What you need is a lightweight, reliable, repeatable landing mechanism. Kergarin used a vertical powered landing directly on the engine bells, which is I believe the lightest possible way to do it (since you're not carrying anything that's neither fuel nor engine back into space). That works fine for biome-hopping, as long as you're reasonably capable with landing things; since you're hopping you can afford to keep a little margin for the landing unless you're pushing a long hop (e.g. over the oceans).

 

 

 

 

[GoSlash27]

46 minutes ago, foamyesque said:

 

What you need is a lightweight, reliable, repeatable landing mechanism. Kergarin used a vertical powered landing directly on the engine bells, which is I believe the lightest possible way to do it (since you're not carrying anything that's neither fuel nor engine back into space). That works fine for biome-hopping, as long as you're reasonably capable with landing things; since you're hopping you can afford to keep a little margin for the landing unless you're pushing a long hop (e.g. over the oceans).

 

 

 

 

foamyesque,

 Again, if you say so. But to be clear that's not what I need because I have no intention of doing such a thing.

Best,
-Slashy

[foamyesque]

Oh good grief

 

(EDIT: Also, winged biome-hoppers on Eve work great. You can't SSTO with them, because the wings and gear chew up too much of the mass budget, but it's far and away the fastest and easiest way to explore the planet)

Edited January 11, 2017 by foamyesque

[GoSlash27]

40 minutes ago, foamyesque said:

Oh good grief

foamyesque,

 What? You're the one who insists this would be easy, yet I've never seen you or anyone else actually attempt it. Seems to me that if anybody "needs" something to do this, it's you. I'm not sure if it's even possible, seriously doubt it would be "easy", and have zero interest in trying it.

 Although, as I've said, I'm interested in seeing someone try...

Best,
-Slashy

[foamyesque]

3 minutes ago, GoSlash27 said:

foamyesque,

 What? You're the one who insists this would be easy, yet I've never seen you or anyone else actually attempt it. Seems to me that if anybody "needs" something to do this, it's you. I'm not sure if it's even possible, seriously doubt it would be "easy", and have zero interest in trying it.

 Although, as I've said, I'm interested in seeing someone try...

Best,
-Slashy

 

... you don't think biome hopping on Eve is possible? Or is it specifically getting to the mountaintop? Or what?

 

Edited January 11, 2017 by foamyesque

[GoSlash27]

50 minutes ago, foamyesque said:

(EDIT: Also, winged biome-hoppers on Eve work great. You can't SSTO with them, because the wings and gear chew up too much of the mass budget, but it's far and away the fastest and easiest way to explore the planet)

Yep. But if you're using additional vehicles to explore then there's no point in making the ascent vehicle SSTO.

3 minutes ago, foamyesque said:

... you don't think biome hopping on Eve is possible? Or getting to the mountaintop? Or what?

foamyesque,

 I *know* that biome hopping on Eve is possible, as is flying to a mountaintop. I don't know if it's possible to do all of that in a single SSTO vehicle, I *seriously* doubt it would be easy, and I'm certain it's too risky a proposal to seriously consider when there so many cheaper, easier, and safer alternatives.

 Best,
-Slashy