SSTO to Eeloo: Can it be done?

[tavert]

According to this thread maximum theoretical dV for LV-N barely allows to build Eeloo SSTO wcich is capable of landing and return.

I doubt that anyone (okay, any more than 1-2 people) is able to make it.

Using ions is much more easier (but much more tedious).

Max theoretical dV for LV-N is over 17 km/s, which is plenty for an Eeloo round trip. It's difficult, but definitely possible. What would be immensely difficult and only marginally possible with some extreme gravity assists would be a rocket-only SSTO Eeloo round trip (no jets, no ions). The record for rocket-only SSTO delta V remaining on-orbit is around 4 km/s. Probably not enough.

[koshelenkovv]

Yes, 17 km/s with infinite number of fuel tanks

In reality, it will be something about 10 km/s (if you manage to build such spaceplane in the first place)

Yes, it's possible, and yes, it's hard, that's why I doubt that enough people here is able to complete this challenge, to make some competition and fun.

It's just too hard.

[numerobis]

Whoa! HOWTHEHECK!

There is no way he should have been able to send a spaceplane to Eeloo with that little fuel.

If he posts it I will ask him about that. I would be very surprised if that thing was 55% rocket fuel after reaching orbit. It didn't look like it.

Looks to me like it's about 22t total on the pad, of which 12t is rocket fuel and 1.5t is jet fuel. The number of intakes is more than enough to make orbit with just a tiny spurt from the rocket. Assuming you dump the jet fuel upon leaving the atmosphere, it's a bit more than 55% rocket fuel on orbit.

It should be possible to shed a couple tonnes off that airframe, too: the bulk of the savings is to use one jet rather than two, mounted inline behind the nuke, with a cube strut behind the nuke -- that somehow makes the nuke's exhaust go through the jet engine without damaging it. But also, you can use the Mk2 fuselage rather than Mk1, or two Mk1/Mk2 adapters if that's enough fuel. Ditch the nose cones. Use a bunch of delta-deluxe winglets rather than delta wings and tail fins (they get a lot more lift per mass). If you can do all that, you can drop the FL-T400s to FL-T200s and still maintain the same fuel fraction in orbit.

Edited December 9, 2013 by numerobis

[impwarhamer]

[*]Overshoot: escape Kerbolar Orbit BEFORE reaching Eeloo. +100

technically, it is impossible to escape Kerbolar orbit, as it is the only point of mass in the universe and as space is not expanding, you will forever be pulled towards it.

Saying that, it does still say 'Sun escape' when you burn prograde for long enough, so i guess that's how you get the points.

[tavert]

It should be possible to shed a couple tonnes off that airframe, too: the bulk of the savings is to use one jet rather than two, mounted inline behind the nuke, with a cube strut behind the nuke -- that somehow makes the nuke's exhaust go through the jet engine without damaging it. But also, you can use the Mk2 fuselage rather than Mk1, or two Mk1/Mk2 adapters if that's enough fuel. Ditch the nose cones. Use a bunch of delta-deluxe winglets rather than delta wings and tail fins (they get a lot more lift per mass). If you can do all that, you can drop the FL-T400s to FL-T200s and still maintain the same fuel fraction in orbit.

Yep, check the version he took to Moho, tighter margins on that one. Dropping from two jets to one is marginal though, tough to get off the ground and into orbit with much more than 10-15 tons on only one jet.

Edited December 10, 2013 by tavert

[numerobis]

Even in a two-body Newtonian universe, you can reach escape velocity: just go fast enough that gravity approaches zero faster than your speed does.

[numerobis]

Yep, check the version he took to Moho, tighter margins on that one. Dropping from one jet to two is marginal though, tough to get off the ground and into orbit with much more than 10-15 tons on only one jet.

I'm failing to find it; do you have a link? I see references to Stochasty wanting to try, and him referencing the plane he made -- but I'm missing the in-between stage.

[tavert]

http://forum.kerbalspaceprogram.com/threads/11214-The-K-Prize-100-reusable-spaceplane-to-orbit-and-back?p=697351&viewfull=1#post697351

[numerobis]

Thanks! I see a few hundred kg to save... but not much more than that.

I've managed to lift 20t per turbojet with a lot of intakes (about as many as Stochasty has), but it was, as you say, pretty marginal.

[Stochasty]

If I were to try to improve my craft, I'd keep the two jets and scale up to about ~30 tons takeoff weight; I can probably manage ~8.5 km/s dV on orbit if I do it right (Mesklin's design manages 8.2 km/s on 31 tons liftoff weight, and uses a pod rather than a seat). You are right, numerobis, about being able to shave additional dry weight by changing to deluxe winglets. I wasn't really trying to be optimal when I first made the design; the original motivation was a discussion with tavert about doing a double Mun run, so I was just scaling up and improving an old design of mine back from the 0.18 days. I'd build her differently if I were to try again.

Regarding rocket-SSTO to Eeloo: I've had a lot of practice with the Kerbin-Jool-Eeloo run between the trip linked above and my work on the gravity assist tutorial, and the best I've managed to date was insertion into low Eeloo orbit for just under 2.5 km/s. Down and up on Eeloo will run another 1.2 km/s, and it takes 300 to get back to Jool (and back to Kerbin for free from there). So, a perfect trip using that route will run you ~4 km/s; in the ballpark for a rocket SSTO, but only just.

There are additional tricks you can use to shave off up to another 1 km/s, though. One way would be to use multiple Kerbin encounters and a series of deep space maneuvers in route to Jool (metaphor had a good pattern for getting there in his single launch Grand Tour post, and told me he saved around 500 m/s over a direct transfer). Another is to go Kerbin-Eve-Kerbin to get a boost. The problem with either of these methods is timing your arrival at Jool so that you hit the window to get to Eeloo (it's a long window - several weeks leeway on either side - but it happens infrequently, and doesn't often line up with an efficient transfer from Kerbin).

Edited December 15, 2013 by Stochasty

[numerobis]

Are there any pork chop plot tools that chain together to produce a total itinerary? As in, tell it you want to go Kerbin-Eve-Kerbin-Jool-Eeloo and it tells you when to leave?

[Stochasty]

Not that I've come across. I do it by working my way backwards: start with the final window, and then look for transfers that arrive during that window to determine when you need to leave the previous target. Also, try to match the insertion delta-v from the arriving trajectory with the ejection delta-v of the outgoing transfer, otherwise you will need to make a burn during the flyby. It's a pain, though, and more trial and error than anything else. The best I've managed to work out for planning an itinerary was the Kerbin-Mun-escape-Kerbin-Eve-Kerbin trajectory I used for the walk through at the end of my assist tutorial, and I managed that only because I new I could pull off part of it ahead of time. (Also, it wasn't a perfect chain, but involved a 4:3 Kerbin resonant orbit after the Mun encounter, and a 1.5-solar-orbit transfer to Eve (that is, I circled Kerbol 1.5 times waiting on the Eve encounter.)

[TimMartland]

I saw a video of an SSTO flying to laythe, landing, deploying a really big mobile base and returning. It had about 1,000,000,000,000,000 parts!

[Mesklin]

numerobis, also you can try to use this program for planning grav sling to Eeloo over Jool.

[Nao]

I've always wondered if SSTO principle allowed undocking part of the craft and then redocking it before return to Kerbin.

All SSTO's i've seen are single shot planes that never loose or gain parts. But as i understand the idea of SSTO is to return with the whole craft excluding fuel (and other consumables) to kerbin surface. So docking should be valid strategy.

Using docking for Eeloo and maybe even an Tylo SSTO could be possible, but i'd like to know other players thoughts on this mathod.

[tavert]

Mesklin's "Dedal" did just that. He undocked the nuke engine, a little bit of fuel, and a seat to bring a Kerbal down to Tylo, then brought it back up to re-dock with the rest of the plane and return to Kerbin. Pretty impressive, and good to know it's possible, but not quite as extreme a feat as bringing the whole thing down to Tylo's surface (don't think the round trip is possible there).

[Moar Boosters]

I've always wondered if SSTO principle allowed undocking part of the craft and then redocking it before return to Kerbin.

All SSTO's i've seen are single shot planes that never loose or gain parts. But as i understand the idea of SSTO is to return with the whole craft excluding fuel (and other consumables) to kerbin surface. So docking should be valid strategy.

Using docking for Eeloo and maybe even an Tylo SSTO could be possible, but i'd like to know other players thoughts on this mathod.

Well I think the main thing that makes people like SSTO's is that they're reusable....... so something like that would definitely qualify.

[D-licious]

Please link a craft file!

[SkyRender]

Threadcromancy is frowned upon; just a heads-up.

Incidentally, I may have come up with a workable prototype for this challenge, and an absurdly lightweight one at that. Only problem: I have Interstellar installed at the moment, meaning the heat levels destroy the turbojets before I can get up to altitude. Bummer.

[Captain Woof]

I've got a Space plane with 7200m/s^2 delta V left once reaching a circular orbit of ~90,000km around Kerbin and 4000m/s^2 left when zooming past Eeloo at 2000m/s (with my horrible skills). I call it the Viper and it weighs under 40tonnes. Really got to post some pics up soon. Joined the forums just to show it off to the public! ;D

Yes, it is completely stock.

No, it does not use ION engines.

No, I did not glitch anything (except for a little air hogging. 10 intakes for 3 jet engines)

And to make it harder for myself, I installed FAR and interstellar mod. Overheating was no problem and FAR might have even helped a bit.

It's even got some lights, solar panels and a reaction wheel for convenience.

It's actually a very old design of mine I built back in 0.19 and I just rebuilt it just to see if it would amaze me if I had MechJeb to take over my horrible planetary transfer skills. Going to submit it to the K-prize thread soon.

[cubinator]

I made an SSTO rocket that did this and more, but it uses ISRU. Does that count as refueling?

[panzer1b]

Well, i JUST finished a new SSTO that gets 7.33km/s dV after LKO.

Provided i can do it efficiently (and perhaps with a grav assist), i feel Eeloo is more then doable (especially if i use jool to help match planes and AP as thats where alot of dV will be wasted). It is currently 36T on the runway, and powered by a cuclear-rapier drive (a rapier with a nuke behind it clipped together). After i finish a mission to laythe, bop and pol with it, im so going to Eeloo and giving it my best shot. If a SSTO to Eeloo can be done, then im just amazed at how crazy my ships are.

one way 100% doable, 2 ways, possibly can be done.

Edited September 12, 2015 by panzer1b

[Vanamonde]

Since this thread was created, there have been substantial changes to aerodynamics and engines. Feel free to create a new thread on the subject, but we'll be closing this thread now so that people are not confused by a mixture of new and old information.