Eve SSTO: any possible ways?

[KerikBalm]

On 1/14/2017 at 2:38 PM, Sharpy said:

 To reach orbit from Eve, even 12km, you need a big, heavy rocket. To lift such a rocket you need a mighty propeller. And to lift that propeller to orbit from Eve...?

I suggest you try Kerbin first. SSTO that goes, say, 5-8km up on propeller, more if you can manage it, the rest on rockets. If it works on Kerbin, it might work on Eve, but if it doesn't work on Kerbin, you can be sure as hell it won't work on Eve.

I was going to suggest that... make a stock prop plane that can SSTO on kerbin first, where the prop is functional and able to lift the entire fully fueled vehicle... and then have said stock craft get to orbit with 1,000 dV left. Ie... you need to make a stock craft that can get to kerbin orbit, and then go to minmus (at least a fly by)

On 1/12/2017 at 10:52 PM, foamyesque said:

As for tall-and-spindly, that's true to some extent but it's actually less true on Eve than nearly anywhere else because of the huge multipliers from keeping your TWR up. If you look at the examples provided you can see they have pretty substantial footprints.

Well, its more of the huge penalties for low TWRs... which is equally true on Kerbin or Eve. Its just that it takes a bigger footprint to get the same TWR on Eve because of the reduced thrust from the high surface pressure, and then the 70% higher surface gravity. You need a much bigger footprint to get the same TWR, but make no mistake, aerodynamics are very very important on Eve.

That footpring issue is one reason why the vector is such a great engine for Eve ascent vehicles- its a lot of thrust for a small footprint.

I think this is from around 1.05, it was one of the lowest sea mass/kerbal sea level eve landers in a challenge to make eve sea level landers (it wasn't the lowest, but it was mine, Foxster and astobond beat me if I remember).

Well, thats it in the ascent configuration... I later modified it to put aerospikes at the bottom of those side stacks for a bit of extra TWR. Its still rather tall and spindly.

Spoiler

Towing configuration+ descent configuration (the 2.5m docking port burns up during descent

 

As you can see, its got some stuff added to keep it stable during descent:

Then the heat shields jettison, the parachutes deploy, and it does some propulsive landing using the fuel in the pods at the top which also have all the science equipment. The science pods jettison and generally survive the fall to be operated by the kerbals... thats why there's two of them anyway. If one is good with the timing, you jettison them rigft before touchdown so their parachutes don't cut.

Liftoff involves decopling the landing legs simultaneously with full throttle to the engines:

then the side fuel tanks drop off (or "boosters" if you want to call them boosters when they have aerospikes at the bottom). At this point its accelerated to roughly terminal velocity, and is tipping over, and its here that TWR starts to become less important than drag.

then its just the core

at this point its more horizontal than vertical, and low drag is more important than high TWR

aaaannnnd... orbit:

 

[Kergarin]

On 8.1.2017 at 0:17 PM, rkarmark said:

NO if you want an eve ssto there are no way around landing on a mouintain top and refuling

@Kergarin is expert he also made a few videos:

and

 

Thanks for mentioning me 

I'm actually scaling this down to the smallest possible SSTO that can refuel by isru in a short time. There is a lot to optimize 

[Reusables]

Okay, It barely made an orbit on Kerbin with nukes & aerospikes configuration.

Spoiler

Forgot screenshot of the propeller stage of the launch...

Engine started on 7km.

Wet mass: 94t
LF+O composition: 30t
LF only(wings): 18t
Dry mass: 46t

So it seems that it's nearly impossible to make propeller planes get to orbit.

But there's more configurations to test:

1. Nukes & Vectors

    The boost stage needs more TWR to go up faster, so Vectors should be better for this.

2. Nukes only

    As spaceplanes can fly in the denser atmosphere with lower TWR, it could be better to optimize the plane for nukes.

   Instead of the aerospike engines and LF+O fuels, more nuke engines can give enough thrust during flight on the higher atmosphere.

3. Aerospikes only

    Aerospike only plane gets its advantage from high TWR and lift, even on the lower atmosphere.

    In this case, it'd be important to give it more mass.

4. Vectors only

    Basically 3 with a bit better TWR and a bit worse Isp.

[Wcmille]

Also see this discussion:

There are several problems to solve:

1) Landing.

• Landing with full tanks means a high ballistic coefficient. I never solved this.
• Landing with empty tanks means you need to either refuel with a drill and ISRU that you carry or that is provided by something on the surface. These will either limit you to landing somewhere that has ore, or you need something with wheels.

2) Sub-orbital Flight

• I like mammoths; an SSTO is going to be bigger than a staging craft. You want to get out of the soup as fast as you can. There is tremendous d/v loss at low altitude. Aerospikes only seem better to me if you are willing to stage.

3) Orbital Flight

• It might be possible to get high enough that you use something like a NERV to go orbital.
• You could also get "caught" by an orbital ship that does a rendezvous and then accelerates to orbit again. This would be very daring. The main problems are fast rendezvous, and a connection that doesn't break due to fast acceleration. I suspect this orbital ship is very, very large.

 

[gilflo]

On Nukes only you can climb to 14kms, + I did this 1.1.3 on a modded SSTO that separates in rockets from 14kms, kind of launching a rocket at 14kms in Eve atmo, you do not need so much DV then to get in orbit (something like 4000DV ...)

Eve atmo being very dense may be you can optimize nukes with very long wings like a glider, then at 14 kms eject wings and nukes and continue on rocket engines with a smaller aircraft. Nukes to climb to 14 kms were the heaviest part....It was  5 giant nuke engines from Atomic Age.

I did not think of making a glider because i thought that atmospheric entry would be impossible with a glider.....

 

[Carl]

For what use it may be, my Hexdecuple Mammoth:

 

 

Yes thats 12 FLT800 tanks with a vector on the bottom wrapped around a mammoth. Lots of compact thrust in that thing. Getting it down, getting eough tansk o in a landing stable config, e.t.c. i leave upto you, but may help given the likly low aero compared to 4 mammoths.

 

IMo obvious options for reusable Eve landing craft.

 

1. Refuel on surface, may not ben enough even with quite big designs though from some locations.

2. With credit it to Wicmillie, a suborbital flight that is caught on the way up by somthing else and then boosted.

3. A 2 stage design in which the bottom stage is actually landed separately on eve from the lander, (which also serves as the eve takeoff upper atmosphere stage), and you dock the two to each other on eve surface, then use the bottom stage to boost the upper stage, whilst the bottom stage lands back on eve to be refueled and used for the next flight, (The Space Shuttle was supposed to be lifted by a booster like this known as the Flyback F-1, but budget constraints forced them to go with reusable solids plus expended big orange tank in it's place).

4. When in orbit, refuel from Gilly, possibly via docking at a station, (my mun/minmus landing is going to be done like this, same for Duna, Dres, Joolian moons, (well at least the three easy ones, not sure how Laythe and the other one will be handled yet), not sure about Moho and Eve yet either. That makes getting up/down much easier as the design doesn't have to go from Kerbin orbit/surface to Eve before landing and taking off again.

Edited January 21, 2017 by Carl

[Zeiss Ikon]

Hmm.  Never been to Eve myself (never been more than a few hundred km past Mun, come to that, I'm kind of new to this stuff).  However.

If Eve's atmosphere supports combustion engines like jets, it does seem that electric propellers, powered by either RTG or solar (or a combination) plus batteries for a short power burst should be capable of lifting a plane that has jets/RAPIER engines to a high enough altitude for those engines to be effective (based on this thread, something above 10 km from sea level).  From there, aside from what happens to the propellers at super/hypersonic speeds, it's a normal spaceplane launch, seemingly.  If you have a plane that can land on Kerbin and return to orbit without refueling, and it has propellers capable of climbing (even a little) at Kerbin sea level, it should be able to haul itself high enough on Eve, since the propellers and wings will both work better in the soup than at Kerbin normal.  Now, if there were a usable way to retract electric propellers...

[Carl]

EVE's atmosphere does not support jets.

[Zeiss Ikon]

Well, I suppose there's always Larry Niven's solution to getting a crewed vehicle off real Venus.  Balloon (in the story, Becalmed in Hell, it was the hydrogen tank that brought them from Earth, with the hydrogen heated with an IR laser to improve its lift), then nuclear ramjets (which need no oxygen), then transition to rocket when the air's too thin for the ramjets.  Don't think that will fly without mods, though.

[Carl]

Yeah that would need mods. And nuke planes are probably enough to give certain people fits. You can read about probably the most insane IRL example of the concept here: https://forums.spacebattles.com/threads/the-madness-of-the-lockheed-cl-1201.219823/

Very kerbal.

 

Also this quote from the thread feel so appropriate too:

 

Quote

I have to say this:

Jesus Christ, I thought the Nazis were whacky.

 

[Reusables]

4 hours ago, Wcmille said:

Also see this discussion:

There are several problems to solve:

1) Landing.

• Landing with full tanks means a high ballistic coefficient. I never solved this.
• Landing with empty tanks means you need to either refuel with a drill and ISRU that you carry or that is provided by something on the surface. These will either limit you to landing somewhere that has ore, or you need something with wheels.

2) Sub-orbital Flight

• I like mammoths; an SSTO is going to be bigger than a staging craft. You want to get out of the soup as fast as you can. There is tremendous d/v loss at low altitude. Aerospikes only seem better to me if you are willing to stage.

3) Orbital Flight

• It might be possible to get high enough that you use something like a NERV to go orbital.
• You could also get "caught" by an orbital ship that does a rendezvous and then accelerates to orbit again. This would be very daring. The main problems are fast rendezvous, and a connection that doesn't break due to fast acceleration. I suspect this orbital ship is very, very large.

 

Thanks for the tips.

Since propeller planes can get out of the dense atmosphere, so I thought aerospikes would be better. But its TWR is lower than I thought...

And imo reentry should be easier since propellers are also airbreaks.

2 hours ago, gilflo said:

On Nukes only you can climb to 14kms, + I did this 1.1.3 on a modded SSTO that separates in rockets from 14kms, kind of launching a rocket at 14kms in Eve atmo, you do not need so much DV then to get in orbit (something like 4000DV ...)

Eve atmo being very dense may be you can optimize nukes with very long wings like a glider, then at 14 kms eject wings and nukes and continue on rocket engines with a smaller aircraft. Nukes to climb to 14 kms were the heaviest part....It was  5 giant nuke engines from Atomic Age.

I did not think of making a glider because i thought that atmospheric entry would be impossible with a glider.....

 

Does the nukes work in low atmosphere? Also eve jets could be better for with modded entries...

 

1 hour ago, Zeiss Ikon said:

Now, if there were a usable way to retract electric propellers...

I implemented reliable way to re-dock propellers and have them point parallel to the airstream. The real problemoney is their mass...

43 minutes ago, Zeiss Ikon said:

Well, I suppose there's always Larry Niven's solution to getting a crewed vehicle off real Venus.  Balloon (in the story, Becalmed in Hell, it was the hydrogen tank that brought them from Earth, with the hydrogen heated with an IR laser to improve its lift), then nuclear ramjets (which need no oxygen), then transition to rocket when the air's too thin for the ramjets.  Don't think that will fly without mods, though.

Eve is much easier with mods. There was a thread about modded eve ssto feasibility, which offeredseveral candidates.

Edited January 22, 2017 by Reusables

[gilflo]

4 hours ago, Abastro said:

 

Does the nukes work in low atmosphere? Also eve jets could be better for with modded entries...

 

 

Yes special Nuke from Atomic age, but very heavy.......because no fuel needed

4 hours ago, Abastro said:

 

 

Edited January 22, 2017 by gilflo

[KerikBalm]

18 hours ago, Abastro said:

Okay, It barely made an orbit on Kerbin with nukes & aerospikes configuration.

...

So it seems that it's nearly impossible to make propeller planes get to orbit.

But there's more configurations to test:

1. Nukes & Vectors

    The boost stage needs more TWR to go up faster, so Vectors should be better for this.

2. Nukes only

    As spaceplanes can fly in the denser atmosphere with lower TWR, it could be better to optimize the plane for nukes.

   Instead of the aerospike engines and LF+O fuels, more nuke engines can give enough thrust during flight on the higher atmosphere.

3. Aerospikes only

    Aerospike only plane gets its advantage from high TWR and lift, even on the lower atmosphere.

    In this case, it'd be important to give it more mass.

4. Vectors only

    Basically 3 with a bit better TWR and a bit worse Isp.

I find that Aerospike TWR is lacking, and in particular their thrust per unit cross section is lacking. While I can make reasonably small asparagus aerospike ascent vehicles from eve sea level, there is an altitude range (I forget what it was, but IIRC, launching from 7km on eve is in the range or close to it) where Mammoths/Vectors get better atmo ISP.

I think aerospikes only won't work. Maybe you can have them, and shut down vectors once you dont need as much TWR, and a lot of fuel mass is gone.

Nukes only(ie only "rocket" propulsion, one still uses jets) barely works on Kerbin (from a TWR, not dV perspective) with turboramjets and rapiers. Those stock props aren't going to get anywhere close to the speeds and altitudes of a turboramjet. So you'll need a lot more lift (as you don't get halfway to orbital velocity, and have a lot of "centrifugal" acceleration cancelling out G), meaning more drag, and less effective TWR. 

One nukes in general: On Kerbin, their TWR is 2:1 - not very high. On Eve, their TWR is a mere 1.176. Try making a LF only design on kerbin with the nukes thrust limited to 60% - even using turboramjets... This also means that the stock props are going to perform worse.

Take your kerbin SSTO design, and add an extra 70% of "deadweight" (I suggest ore cans clipping in a service bay so as yo have a minimal effect on drag) - see if the thing can still fly under the stock props (no need to try the rocket portion, because there it wouldn't be comparable). - or is it possible to "throttle" your stock props down to 58.8%?

Again, Eve orbit is about 1 km/s faster than kerbin orbit, so you need to get to kerbin orbit with 1 km/s left

its just not going to work.

9 hours ago, Zeiss Ikon said:

Hmm.  Never been to Eve myself (never been more than a few hundred km past Mun, come to that, I'm kind of new to this stuff).  However.

If Eve's atmosphere supports combustion engines like jets, it does seem that electric propellers, powered by either RTG or solar (or a combination) plus batteries for a short power burst should be capable of lifting a plane that has jets/RAPIER engines to a high enough altitude for those engines to be effective (based on this thread, something above 10 km from sea level).  From there, aside from what happens to the propellers at super/hypersonic speeds, it's a normal spaceplane launch, seemingly.  If you have a plane that can land on Kerbin and return to orbit without refueling, and it has propellers capable of climbing (even a little) at Kerbin sea level, it should be able to haul itself high enough on Eve, since the propellers and wings will both work better in the soup than at Kerbin normal.  Now, if there were a usable way to retract electric propellers...

Eve's atmosphere doesnt. RTGs have inferior power/mass ratios to solar until one goes past the orbit of dres. (fuel cells are another matter, but once high enough in eve's atmosphere that the sun isnt so attenuated, I suspect solar is better... it certainly is at moho). Rapiers and jets are very effective in thick atmospheres, the problem is a lack of oxygen, not that the atmosphere is too thick. If one mods Eve to set the flag to true for oxygen, rapiers and turboramjets will work quite well. (with great TWRs due to the thick atmosphere).

Even ignoring that, it wouldn't be a "normal" spaceplane launch because the orbital velocity is so much higher. It would be more comparable to a single stage to Minmus spaceplane launch (there would still be the TWR issues higher in the atmosphere) - which is doable but not "normal"

2 hours ago, gilflo said:

Yes special Nuke from Atomic age, but very heavy.......because no fuel needed

This thread was explicitly about stock. When people mention "nukes" I think just about everyone here understands them to be talking about the LV-N. There are many mods that role play the engine to be nuclear of some kind or another. You can't just say "nukes" on a thread asking about stock designs, and expect people to know which modded engine (of the many) that you are talking about

Edited January 22, 2017 by KerikBalm

[Sharpy]

12 hours ago, Wcmille said:

 

• Landing with empty tanks means you need to either refuel with a drill and ISRU that you carry or that is provided by something on the surface. These will either limit you to landing somewhere that has ore, or you need something with wheels.

 

Leaving a fully functional module on the surface is not a stage drop - it's payload delivery.

So there's nothing wrong about landing your craft carrying, say, a lightweight ISRU rover and using said rover to refuel on the spot.

Also consider an ISRU-carrying non-spaceplane airplane for Eve. Airplanes behave really nice in lower atmosphere, so having a local ISRU fly up to your landing spot, and drive the last 500m is quite viable.

[magnemoe]

Just now, Sharpy said:

Leaving a fully functional module on the surface is not a stage drop - it's payload delivery.

So there's nothing wrong about landing your craft carrying, say, a lightweight ISRU rover and using said rover to refuel on the spot.

Also consider an ISRU-carrying non-spaceplane airplane for Eve. Airplanes behave really nice in lower atmosphere, so having a local ISRU fly up to your landing spot, and drive the last 500m is quite viable.

You can simply call it an base. 
Had an Tylo SSTO transport I refueled in orbit then at the base, worked well but Tylo works far better for this than Eve as you only need 3 km/s to land or take of. 

[Kergarin]

I do have really really bad news for us all.

Kergarin Aerospace has made some research, and the atmosphere on Eve has changed drastically over the last year.
The pressure in 1.2.2 is much higher than back in 1.1.3 when i made my SSTOs.
The Mammoth is not producing enough thrust anymore.

While it was almost impossible, when I did it, it is now even harder.

See this chart starting at 7500m. Don't even think about a lower place.

Edited January 22, 2017 by Kergarin

[Carl]

On 11/01/2017 at 1:12 AM, 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

 

I spent late last night screwing around and 7kms single stage from Kerbin is flat impossible, never mind Eve.

[GoSlash27]

1 hour ago, Carl said:

I spent late last night screwing around and 7kms single stage from Kerbin is flat impossible, never mind Eve.

Carl,

 My spreadsheet agrees. A 7 km/sec stage from Kerbin's surface is indeed impossible*. in fact, a 7 km/sec stage at 1g acceleration is impossible even in a vacuum.

Best,
-Slashy

*Not counting air breathers

Edited January 22, 2017 by GoSlash27

[Carl]

Yeha in fact a quick look at the cheat sheet says you need better ISP than even a vacuum mammoth, (about the same as a rhino), to get 7km/s period at any initial acceleration. Now a 2 stage setup where the booster flies back to eve's surface, (note flies i this case does not necessarily mean wings), might work. But honestly 7kps even in 2 stages would be tough, the limit for eve looks to be around 3.5kps a stage, and thats a pretty massive upper stage all by itself, (MJ is cool for finding your dv on another planet without going there :p).

Edited January 22, 2017 by Carl

[Carl]

Ok i went and did some more messing, assuming 2.6kps of DV with around a 1.43 TWR at liftoff is adequate to make 20km of altitude it may just be possibble with a 2 stage design in which both stages can be reused, the first from eve surface each time, (though resetting it will be a copper plated poodle, as will joining the stages on the ground for each flight). If anyone want my test craft file to actually see if it works, (i suck at using the console), just shout. Pics below, (once imgur finishes processing them).

 

Edited January 22, 2017 by Carl

[magnemoe]

35 minutes ago, Carl said:

Ok i went and did some more messing, assuming 2.6kps of DV with around a 1.43 TWR at liftoff is adequate to make 20km of altitude it may just be possibble with a 2 stage design in which both stages can be reused, the first from eve surface each time, (though resetting it will be a copper plated poodle, as will joining the stages on the ground for each flight). If anyone want my test craft file to actually see if it works, (i suck at using the console), just shout. Pics below, (once imgur finishes processing them).

You look at an setup a lot like the fully reuseable falcon 9 design, First stage lands downrange, fuel up and jump back to launch pad, second stage has to reach orbit, it can refuel in orbit but has to deorbit and land and be added to the first stage again for an new launch. 

First would be to forget to do this stock, just to mate upper and lower stage would be an nightmare even at KSC.
Use KAS and / or infernal robotic, cranes are pretty realistic after all. 
You would probably need to extend the cut of distance in atmosphere as the upper stage speeds away wile the first stage lands,

Note that the first stage does not have to survive an reentry without dropping parts so you can use disposable heatshields for it as it will only deorbit once, upper stage has to survive reentry many times to make it reuseable.

----
Way larger than I thought. You would need an huge crane to add the upper stage
Guess the crane also work as an launch tower to add kerbals and can be used to repack parachutes.  
 

[Reusables]

4 hours ago, Kergarin said:

I do have really really bad news for us all.

Kergarin Aerospace has made some research, and the atmosphere on Eve has changed drastically over the last year.
The pressure in 1.2.2 is much higher than back in 1.1.3 when i made my SSTOs.
The Mammoth is not producing enough thrust anymore.

While it was almost impossible, when I did it, it is now even harder.

See this chart starting at 7500m. Don't even think about a lower place.

This one seems to be more forgiving for me! (Or more precisely, my props)

[Carl]

Quote

Way larger than I thought. You would need an huge crane to add the upper stage 
Guess the crane also work as an launch tower to add kerbals and can be used to repack parachutes.  

I was thinking skycrane to hoist the second stage onto the first, that stays on EVE's surface, maybe a second to help move the first stage around. You can do it all stock that way. Now if we had proper stock propellers...

Also since the last two shows missed showing here the lower stage ends, (test flight to check the docking ports don;t suffer unplanned disassembly in flight, they're good):

 

Edited January 22, 2017 by Carl

[Cunjo Carl]

It looks like drag cubes were made a little slippier in 1.2.2 . However, the forward face may be a bit grippier at high mach (3+), but careful use of antenna on forward cones has helped that in the past. Given the apparent lower drag, I wonder if a slow-climb space plane might be the way to go up 'till the rocket gets out of the soup at ~20km. If anyone's interested in a old-new Cd comparison, I can run the numbers, but it's a bit of work. I suppose we could also just try flying it and see what happens... Anyone have experience with that? Seems a lot more Kerbal come to think of it!

v 1.2.2

Spoiler

DRAG_TIP // Multiplier to dragcube drag when the face points towards the velocity vector, x value is mach, y value is multiplier
{
    key = 0 1 0 0
    key = 0.85 1.19 0.6960422 0.6960422
    key = 1.1 2.83 0.730473 0.730473
    key = 5 4 0 0

}

.......

DRAG_CD // The final Cd of a given facing is the drag cube Cd evalauted on this curve
{
    key = 0.05 0.0025 0.15 0.15
    key = 0.4 0.15 0.3963967 0.3963967
    key = 0.7 0.35 0.9066986 0.9066986
    key = 0.75 0.45 3.213604 3.213604
    key = 0.8 0.66 3.49833 3.49833
    key = 0.85 0.8 2.212924 2.212924
    key = 0.9 0.89 1.1 1.1
    key = 1 1 1 1
}
DRAG_CD_POWER // The final Cd of a given facing is then raised to this power, indexed by mach number
{
    key = 0 1 0 0.00715953
    key = 0.85 1.25 0.7780356 0.7780356
    key = 1.1 2.5 0.2492796 0.2492796
    key = 5 3 0 0
}

 

 

v 1.1.2

Spoiler

 

DRAG_TIP // Multiplier to dragcube drag when the face points towards the velocity vector, x value is mach, y value is multiplier
{
    key = 0 1 0 0
    key = 25 1 0 0
}

........

DRAG_CD // The final Cd of a given facing is the drag cube Cd evalauted on this curve
{
    key = 0.05 0.0025 0.15 0.15
    key = 0.15 0.0225 0.3 0.3
    key = 0.25 0.0625 0.5 0.5
    key = 0.35 0.1225 0.7 0.7
    key = 0.45 0.2025 0.9 0.9
    key = 0.55 0.3025 1.1 1.1
    key = 0.65 0.4225 1.3 1.3
    key = 0.75 0.5625 1.5 1.5
    key = 0.8 0.66 2.3775 2.3775
    key = 0.85 0.8 2.733777 2.733777
    key = 0.9 0.89 1.1 1.1
    key = 1 1 1 1
}

 

[GoSlash27]

4 minutes ago, Cunjo Carl said:

It looks like drag cubes were made a little slippier in 1.2.2 .

Cunjo Carl,

 You wouldn't happen to be from Pittsburgh, would you? "Slippy" is a Pittsburgh thing...

Go Stillers,
-Slashy