Spaceplane for Duna and Eve

[michal.don]

Hi guys,

I started trying various designs of spaceplanes and SSTOs recently, and became quite comfortable with my ability to get something to LKO and something else back to the spacecentre in one flight. The next logical step is building a plane capable of refueling and going to other planets. However, I have no idea how planes behave in other environments - Duna has lower gravity, but very thin atmosphere, which I suppose will make flying much more difficult, and Eve the other way around - lots of gravity, but a thick atmosphere which could produce much more lift. What is your experience? Does the design have to be much different, and if so, how? More/less fuel to get to orbit, more/less wings needed to fly and land, more/less thrust to takeoff?

Thanks,

michal.don

Edited September 30, 2015 by michal.don

[Sirine]

The next logical step is to install hyperedit mod and test flight your design ssto at real Duna or Eve environment.

Then you will realize there will be no ssto can fit both in 1 go.

Duna 1st. Eve later.

- - - Updated - - -

Technically non-air breathing engine. Cause both planets have no oxygen to burn.

[michal.don]

Well, that's some bad news.... I figured out the oxygen thing, it should be covered by RAPIERs in closed cycle mode. But I would like to solve it without the hyperedit mod, I just don't like the idea of "cheating" this way.... Anyway, thanks for your advice,

michal.don

[Skorpychan]

You'll need very different planes for each one, I'd think. Duna has a thin atmosphere but low gravity, and Eve has a soupy thick atmosphere but vicious gravity.

I'm personally wondering if it's viable to make a spaceplane for Jool, so it can dip down into the atmosphere and boost back to orbit again for science.

[michal.don]

Ok, I'm starting to accept that I won't do it all in one go But I don't really know in which ways the planes should be different for each of those missions. More/less wings? Thrust?

[Skorpychan]

For Duna, I'd think you'd need less thrust but big wings to get lots of lift. For Eve, smaller wings due to thicker atmosphere, but more thrust to push through it. Not TINY wings, though, as there's gravity.

[mrclucks]

There's an atomic jet in Atomic Age that just requires an atmosphere. They do have a weight of 8t so it might only be viable on larger spaceplanes

[tbarcello]

Well, that's some bad news.... I figured out the oxygen thing, it should be covered by RAPIERs in closed cycle mode. But I would like to solve it without the hyperedit mod, I just don't like the idea of "cheating" this way.... Anyway, thanks for your advice,

michal.don

I think there is kethane-powered engine within that kethane mod, that can breathe in duna and eve. But that was long ago, Scott Manley was using one.

[Mastikator]

I think there is kethane-powered engine within that kethane mod, that can breathe in duna and eve. But that was long ago, Scott Manley was using one.

Karbonite had that I think, fuel in the atmosphere of Eve.

Making a SSTO for Duna is pretty easy though, it doesn't have to have wings either, anything that can take off of Eve can take off of Duna easily.

[michal.don]

Ok, thanks for your advise, I'll see what I can do

michal.don

[Whovian]

KSP Interstellar also has jets that can function in any atmosphere.

[Sirine]

Everything can be done with mod installed.

With mod, sense of achievement cut by half, because you can't do it without that particular mod.

Doing it stock and you can tell yourself, you can repeat that achievement on any updates version of KSP without worries of mod following the KSP updates or not.

And you can safely migrate your save file. Continue your mission with KSP updates and no broken save.

[satnet]

For SSTOs your missing a good option for a next destination. Laythe (2nd moon of Jool) is a good next destination because it has oxygen, it has an atmosphere that isn't too thick or too thin, and gravity is a bit lower than Kerbin. It really depends on what kind of challenge you want to tackle.

Laythe - If a plane flies well on Kerbin it probably flies better here. However, you have a long trip so good interplanetary navigation skills are required. Also finding a viable landing spot can be a challenge. The main design challenge is getting enough fuel capacity for the interplanetary journey while remaining light enough when you get there.

Duna - Like others have said if you want it to fly as a plane you need a lot of wings. The atmosphere is thin and it takes a lot of lift to do any good, but the thin atmosphere also means you get nearly vacuum ISP and thrust. The main design challenge is getting enough lift. You probably want to try to land in a low-lying area so the atmosphere is as thick as possible when you land.

Eve - I don't know what it is like in 1.0+ yet, but from what I've heard it remains one of the more challenging places to get anything off of. Getting an SSTO off of Eve will probably require a mod with engines that can use atmosphere. In stock the only advantages of an SSTO are that it can have a TWR less than 1 and it can control its descent and land on a high mountain which reduces the Delta-V required. The main design challenge is getting enough delta-V and TWR to get into orbit. Definitely tackle this one last, it is hard enough with a multi-stage rocket. The SSTO constraints make this very very difficult.

[Hagen von Tronje]

Doing it stock and you can tell yourself, you can repeat that achievement on any updates version of KSP without worries of mod following the KSP updates or not.

You can tell yourself that, but it won't be true. A number of perfectly usable designs in earlier versions are complete bricks in 1.0.4, and for a wide variety of reasons.

I'm not sure I'd consider it "half the achievement" to use a purpose-built part rather than a physics exploit with stock - or do you think radial intakes actually make great boat bottoms in real life too?

On topic, Duna and Eve are pretty much opposites in terms of flight. On Duna, it's very easy to go very fast, as the atmosphere is so thin that drag is practically a nonissue, but stopping and landing is unbelievably dangerous due to the bumpy terrain and poor opportunities for braking, and in-flight maneuvers will feel somewhat floaty even with a ton of wings and control surfaces. On Eve, maneuvering is a snap (you can literally yaw into turns and have it work out fine) and you can brake on a dime (just don't flip!), but don't expect high speeds close to the surface, as the drag is just outrageous.

Also worth mentioning that in stock, rocket engines are the only thing that will operate on Eve, and Eve's atmosphere utterly murders the effectiveness of rockets. I don't think I've ever seen anyone claim to have SSTO'd Eve with stock parts.

The big engine choices for extraplanetary planes seem to be Firespitter/KAX electric propellers (perfect for Duna, thin atmosphere means supersonic props!), and the nuclear jets. I like the one from the Mk2 expansion, it uses enriched uranium and is not good for much on Kerbin but works great on Eve. The props work fine on Eve too, just don't expect high speeds at low altitude.

[JTpopcorn]

If you dont want modded, no one said the ssto cant change in space/refuel. Simply leaving a tank in space with docking ports, so extra engines could be left in orbit for duna, then used for eve would work/look cool.

[FlyingPete]

I'd like to have a jet engine that is designed to operate in a hydrocarbon-rich atmosphere (e.g the kerbal equivalent of hydrogen or methane) by supplying its own oxidiser to burn with the atmospheric reaction mass. If Jool and Eve had such an atmosphere, you could make some pretty cool jet aircraft for dipping into the atmosphere and flying around without landing.

[Hagen von Tronje]

If you dont want modded, no one said the ssto cant change in space/refuel. Simply leaving a tank in space with docking ports, so extra engines could be left in orbit for duna, then used for eve would work/look cool.

Have you seen a single all-stock Eve SSTO, spaceplane or not?

I looked, because I was curious. I found lots of arguments over whether it's possible, but not a single example of a working model, much less in 1.0.4. If you know of one, I am genuinely, sincerely interested, so please share.

EDIT: Further digging, I found this:

http://forum.kerbalspaceprogram.com/threads/132211-Eve-SSTO-Limbo/page3

The ONLY all-stock Eve SSTO I've ever seen, and everyone seems duly impressed by it so I would guess it's a first (or first published).

That is, at least, a jumping board to possibility.

Edited September 6, 2015 by Hagen von Tronje

[Geschosskopf]

The next logical step is building a plane capable of refueling and going to other planets. However, I have no idea how planes behave in other environments - Duna has lower gravity, but very thin atmosphere, which I suppose will make flying much more difficult,

I wrote some guidelines (not really a true tutorial) on flying on Duna. See the link in my sig.

But long story short, if you design a plane specifically to fly on Duna, then flying it there (and making it an SSTO) is INCREDIBLY easy compared to Kerbin. But anything that will fly well on Duna will suck on Kerbin and vice versa because they're totally different environments. The various flight parameters of lift, drag, thrust, and weight (not mass) work very differently so require VERY different ratios of wing to mass, thrust to mass, etc. Plus, Duna (and Eve) have no free-range oxygen so the jets you use to take off at Kerbin are totally dead weight everywhere else but Laythe.

Therefore, I think it's probably impossible to build an SSTO that will work for both Kerbin and Duna as airplane/spaceplane. You might be able to do it as a capsule at Duna, landing with chutes and taking off as a rocket, but then why bother sending a spaceplane? Far more efficient would be to have a Kerbin-only SSTO that delivers stuff to a station, where it's transferred to a conventional interplanetary rocket that takes it a station at Duna, where transfers to a Duna-only SSTO.

With Eve, it's the same sort of thing in needing a specialized Eve-only ship that has no chance at all of working at Kerbin, and vice versa. But all the parameters are different than for Duna. So again, make a specialized spaceplane for Eve and another for Kerbin, stations at both, and a conventional rocket between the stations.

[Red Iron Crown]

Also worth mentioning that in stock, rocket engines are the only thing that will operate on Eve, and Eve's atmosphere utterly murders the effectiveness of rockets. I don't think I've ever seen anyone claim to have SSTO'd Eve with stock parts.

Stock Eve SSTOs are now a thing.

[Hagen von Tronje]

Stock Eve SSTOs are now a thing.

Yeah I saw that thread shortly after saying SSTOs from Eve haven't been done.

Which only makes it that much more impressive, is that the first one you've seen?

[Red Iron Crown]

It is the first I've seen. The reduced dV to orbit meant it wasn't mathematically excluded anymore, I had a few tries at it myself but always fell short. Quite an accomplishment, astrobond is to be congratulated.

[panzer1b]

Karbonite had that I think, fuel in the atmosphere of Eve.

Making a SSTO for Duna is pretty easy though, it doesn't have to have wings either, anything that can take off of Eve can take off of Duna easily.

Anything that can take off of Eve can take off of any body except Jool or Kerbol (although you cant actually land there), Eve is currently the TOUGHEST place to do anything at, its atmo tends to fry anything that isnt super resilienty and or spamming radiators (which for some stupid reason work while flying thru hot air). All in all, an Eve SSTO (which apparently has been done already) can land and takeoff from ANYWHERE including arguable the 2nd hardest, Tylo.

As for Duna, the majority of kerbin SSTOs or planes will work there provided they have good lift (or use a powered/parachute landing system). The only issue is that jets dont work, but almost any rocket engine powered craft will work on duna provided it doesnt have a tough time lifting off from kerbin (just make the landing gear solid as its way more bumpy and higher landing speeds on Duna.

Aside from that, not much i can say. Most of my SSTLs work on Duna, and those donty exactly have excessive wing area either, so anything else should too.