SSTO to laythe and beyond

[panzer1b]

While we all know SSTOs to lathe were pretty easy back in the day, im wondering if anyone can pull it off in 1.0.

The bare minimum requirements are being able to get to laythe, and land one kerbal that can then plant a flag. This can be done in any way whatsoever, provided not a single part is jettisioned during the trip (its SSTO, not space plane).

Now as for the actual challenge specs:

*Craft must be SSTO and land on laythe without any refueling or use of IRSU.

*No debug menu or any cheats such as part.cfg edits, no mods that can affect performance of vessel (the craft MUST be able to perform the same trip after removing all modded parts, although stuff like MJ, KER, ect are still fine for piloting ect).

And as for the scoring:

500 points:

*Successfully landing on Laythe with a single stage craft.

500 points:

*Returning to Kerbin after landing on Laythe with the same craft, again without any refueling.

500 points:

Landing on any other body other then laythe during the trip.

(note: additional 1000-2000 points added for Tylo or anything outside of the Joolian or Kerbin system, and you get over 9000 points for Eve, Eeloo, or Moho as i consider those impossible to even SSTO to directly)

50 bonus points (can be stacked together):

*Under 20t

*Under 100 parts

*Every ton of payload brought and dropped off on laythe (cannot be used as fuel, although dumping fuel with a mod does count).

These engineers managed to land on Laythe with a single stage craft launched from LKO:

550 points for psyberduckling.

650 points for spikes2020.

550 points for Val in the M-5 Space Hustler that just barely managed to return to Kerbin after a botched return attempt.

600 points for PLAD in a very simple ultralight SSTL rocket using alot of gravity assists.

550 points for Foxter that got to laythe in a SSTL

550 points for Batz_10K in a flying wing that made it to Laythe

550 points for CaptainTurboMuffin in a SSTL that carried 4 Kerbals.

These engineers managed a laythe roundtrip:

1050 points for Red Iron Crown in the LSSTL4 that managed a full roundtrip to the surface of Laythe and back to Kerbin.

1400 points for Val in the SSTL H-3 Rhino Mk.3 that dragged a rover and a small aircraft to Laythe as cargo (~8 tons), and then managed to get home afterwards. This is the first MK3 cargo plane that managed to do the trip, and Val used a very efficient gravity assist route along the way to make a lowish dV craft capable of pulling it off.

these engineers make Jebediah look bad:

2000 points for Nerfrums in the StarFlare that landed on Laythe, Pol, and Bop, all with such a terrible TWR that burn in excess of 30 minutes were required.

3100 points for ManEatingApe that bloody landed on Minmus, Gilly, Bop, and Pol along with the usual laythe landing in a single stage with over 9000 dV in LKO.

There are also many other craft that are cool, but the ones above actually made the trip to laythe or beyond (for some inspiring stuff check the actual thread, there are some great dV numbers in LKO that had they been sent to laythe may have made a roundtrip).

(note:all entries go by the honor system, so unless its extremely fishy or suspicious i will assume that if you say you did what you claim you did, and also, if i MISSED anyone, please post here or send me a PM or something, i promise i wont leave anyone out intentionally)

Ohh, and heres my 100% legit (well it has alot of clipping and i used a mod that lets me swap LFO for LF in a tank, but otherwise 100% legit):

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i didnt show the kerbin return as the game was corrupted and i didnt feel like redoing the whole thing from scratch. Anyways, this proves the R version of the HK-201 (which gets almost 6400dV in LKO) works as intended. I just need to get better at ejection burns (perhaps make them in sections as its inefficient to have a long burn over 5 mins around kerbin). With PLAD's eve route via gravity assists, i am positive that one could land this on Bop and Pol along with the usual Laythe landing, and then return to kerbin alive.

Armed version is worse, only gets 4.6K dV in LKO, but even that is adequate for a efficient laythe roundtrip using hohmans. Ohh, and lifting 30 bloody tons with a single rapier is extremely painful, takes forever to get up to speed (although it actually handles great when less then half fuel loaded and no weapons aboard). So much fuel FTW.

Edited September 25, 2015 by panzer1b

[HoloYolo]

Badge and I will waste all my time on this.

[panzer1b]

Badge and I will waste all my time on this.

Working on it!

Ohh, and i need to do a properly documented laythe roundtrip in my upgraded Tri-Fighter, as i managed to just BARELY pull it off with a variant that has 27 fuel tanks with like 18900 xenon!

Ofc its still cheaty, given thats ALL inside a single 1.25m bay, but hey, you gotta do what u gotta do to maintain appearance and functionality (new one also has 2 weapons hardpoints and docking capabilities)!

Might have to add some bonus points for legit non exploity design, as in no abusing of the cargo bays as a way to bypass drag effects.

Edited April 28, 2015 by panzer1b

[HoloYolo]

Working on it!

Ohh, and i need to do a properly documented laythe roundtrip in my upgraded Tri-Fighter, as i managed to just BARELY pull it off with a variant that has 27 fuel tanks with like 18900 xenon!

Ofc its still cheaty, given thats ALL inside a single 1.25m bay, but hey, you gotta do what u gotta do to maintain appearance and functionality (new one also has 2 weapons hardpoints and docking capabilities)!

Might have to add some bonus points for legit non exploity design, as in no abusing of the cargo bays as a way to bypass drag effects.

Sweet, thanks. Will work on tomorrow, gotta go to bed. Good night, and happy flying.

[KotDemopan]

SSTO to Laythe and Beyond?

Why not just SSTL&B?

[spikes2020]

I'm working on this~

Anyone else make it?

I have a question,

Could i launch an SSTO into Kerbin orbit and then separate leaving that half in orbit take another SSTO to Laythe land, return, and redock in kerbin orbit and land? All without refueling? Would this count?

Everything would be reusable no left parts in space or another planet.... I might need to turn off my TAC life support mod though.....

[Captain Sierra]

*Craft must be SSTO and land on laythe without any refueling or use of IRSU.

Under stock this is actually pretty close to impossible without the abuse of ion engines.

Way I see it you got three options:

1. SSTM (single stage to Minmus) with an onboard ISRU suite to top off the LF tanks when you get there, being sure to burn off most of your oxidizer previous.
   
2. stop at an LKO fuel depot, offload your oxidizer, and top up on LF.
   
3. get creative (and probably very clippy) with ion engines and tiny tiny planes.
   
4. resort to mods (I can convert one of my payload SSTOs to do it if I tuck in some argon and a reactor from the Near Future mods into the cargo bay & throw a PIT on the back)
   

[Red Iron Crown]

Fairly sure it's doable with nukes, observe dV remaining once in orbit:

If I replaced the cockpit with a lighter single-seat one and replaced the crew tank and docking port with more LF it should be fairly easy.

Gonna have to put together an entry, I think.

[spikes2020]

Mine looks kinda like "Red Iron Crown's" but i have only 1 atomic engine in the middle, 2 rapiers, and 2 ramjets. Less engines means less dead weight, only issue i have is while running my Atomic engine i only have like .1-.2 T/W ratio. I have 4 Scoop intakes and 4 pre-coolers, im not sure if the pre-coolers are worth it or not. I currently make it to orbit with 5T of cargo in a Bay. if i fly empty i have an extra 1k of delta V in orbit. I think i can take the bay out and add that as fuel, take out the 2 seats and make it a single seat. Should get me an easy 6-7T of extra fuel.

I should be able to make it Laythe... Not sure about making it back though, Jool gravity well is huge.... Maybe if i can bounce around the moons or something... Anyway if i can get 2k DeltaV in kerbin orbit by the pork-chop plot i should make it easily without having to use sling shots...

http://wiki.kerbalspaceprogram.com/images/7/73/KerbinDeltaVMap.png

[psyberduckling]

Don't have detailed logs, and don't care much for badges, but this ship made it easily (went the direct route, no slingshot via Eve)

She's 43 parts, 53.1t, 6.1m high, 12.4m wide and ... 31.3m long.

Here's the craft file: http://cyberiantiger.org/PythonMk1.craft

Fuel tank balancing is a pain, and don't use the physics acceleration during re-entry, it tends to cause her to oscillate the nose up and down violently before exploding into little bits.

Edited June 8, 2015 by psyberduckling
Fix borked image link.

[herbal space program]

I managed to get my ship on LKO with around 3600 dV in fuel left burning the nuke engine, 27000 burning the RAPIERs on air. I think that if I squeeze every bit of dV out of gravity assists to get there, I might just be able to make it back, but it isn't going to be easy. Does anybody have a link to a primer of some kind on multiple gravity assists? I got nowhere trying to work it out on my own last night. The best I could seem to do off of Eve was halfway to Duna orbit, which doesn't seem to get me anything.

[Captain Sierra]

I came up with a modular design which switches out most of its LFO tankage for pure LF tankage once in LKO at a fuel depot and undocks 4 of the RAPIERs to load on 2 NTRs. Heavily banking on Laythe's lower dV to orbit, but it might be doable, can switch back to original components and head back down to kerbin.

[Mister Dilsby]

How about 11 tons, 27 parts, and 3800 m/s dV left in LKO? Have not taken it to Laythe yet, but it can definitely get there. I might also try tuning the ascent profile to save a little jet fuel for the destination.

I give you... the Kooljer 2! (electric boogaloo)

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[Red Iron Crown]

That TWR, tho. About 100 minutes of burning for ejection, and that's for an efficient transfer that likely won't be possible at that TWR. Kudos to you if you manage to pull it off.

Edit for below: I think you slipped a decimal place, your numbers give 5700s for 2000m/s, or 95 minutes. Even my lowest TWR precomputed tables assume 100m/s per burn, or 4.75 minutes at that TWR, which you'd do nine times followed by a 45+ minute burn. Prepare to build some character.

Edit: It's an edit war!

Edited June 9, 2015 by Red Iron Crown

[Mister Dilsby]

That TWR, tho.

Well let's see... mass is a bit under 6t, thrust 2kN, so it adds one m/s every 2.85 seconds. If the total dV required to get to Jool is about 2000, then I'm looking at 90+ minutes of burn. Eh, yeah, that's pretty awful.

Hey, if only there were a table somewhere of precomputed low-TWR interplanetary transfer burns...

ETA: I didn't lose a decimal before, I inverted. Was frantically trying to correct before you replied

Edited June 9, 2015 by Kuzzter
bad maths

[herbal space program]

Well let's see... mass is a bit under 6t, thrust 2kN, so it adds one m/s every 2.85 seconds. If the total dV required to get to Jool is about 2000, then I'm looking at 90+ minutes of burn. Eh, yeah, that's pretty awful.

Hey, if only there were a table somewhere of precomputed low-TWR interplanetary transfer burns...

ETA: I didn't lose a decimal before, I inverted. Was frantically trying to correct before you replied

As RIC pointed out to me in another thread, that 2000 m/s dV is only if you do the whole burn at Kerbin periapsis. How much will you actually lose smearing it out that much, especially on the last burn? This has been an issue for me even with a nuke at TWR around 0.2-0.25, where my last burn would take only around 6 minutes.

Edited June 9, 2015 by herbal space program

[Mister Dilsby]

Well now I HAVE to do it... or else be sensible and just put a little more fuel in my TRJ+LVN SSTO... no, no, that's not Kerbal enough.

[Red Iron Crown]

This might be illuminating. Jool transfer for just over 1000m/s. (Crossposted from your grav assist thread, herbal.)

[herbal space program]

This might be illuminating. Jool transfer for just over 1000m/s. (Crossposted from your grav assist thread, herbal.)

That is most definitely illuminating! Thanks! If only he'd had a slightly wider shot at the beginning that showed where Jool is. I think I can still figure it out from that though. I spent hours last night trying to puzzle this out by trial and error but gave up. If I can actually make the Jool system with only 1000+/- dV, then I think maybe I can pull it off!

[psyberduckling]

As RIC pointed out to me in another thread, that 2000 m/s dV is only if you do the whole burn at Kerbin periapsis. How much will you actually lose smearing it out that much, especially on the last burn? This has been an issue for me even with a nuke at TWR around 0.2-0.25, where my last burn would take only around 6 minutes.

To be fair, the first 950m/s can easily be burnt at or very close to periapsis in ~45 burns of one minute length, just have to dodge moons, and get your ap/pe aligned correctly for your transfer window. Hell, you don't even have to dodge moons for the first 800 or so m/s.

The last 1000m/s is the problem, though if you use an Kerbin-Eve-Jool transfer it's much less which could be burned close to or at periapsis. Gravity assist via the Mun probably isn't worth it for the 200 m/s dV you'd save, given in a low TWR ship, you're already jumping through enough hoops to align your pe/ap correctly with the transfer window, accounting for deflection by the Mun's gravity becomes very hard (Ideal gravity assist would give you a 90 degree deflection, but i don't think the Mun's gravity is enough at the velocity you'd need to be going to get to either Eve or Jool).

I've done this a few times in low TWR ships to save fuel (admitedly not quite so low as the ship in question).

edit: Mostly I've done this in my ISRU space plane, didn't quite have enough fuel to get to Minmus to refuel if I just burned straight, then when I leave Minmus I burned for an orbit with a periapsis just above Kerbin atmo, aligned with the transfer window. I tried to do the same back from Jool, but I messed up the exit angle (as an aside you can get almost anywhere with very little fuel from Pol using this trick, the problem is slowing down when you get where you're going, when you're going 9000 m/s at Jool periapsis adding a little dV goes a long way).

Edited June 9, 2015 by psyberduckling

[herbal space program]

To Gravity assist via the Mun probably isn't worth it for the 200 m/s dV you'd save, given in a low TWR ship, you're already jumping through enough hoops to align your pe/ap correctly with the transfer window, accounting for deflection by the Mun's gravity becomes very hard (Ideal gravity assist would give you a 90 degree deflection, but i don't think the Mun's gravity is enough at the velocity you'd need to be going to get to either Eve or Jool).

I actually already got the Munar assist to Eve part worked out for my ship. IIRC, I had to make only a minor boost at my Munar periapsis to get an Eve encounter, saving me maybe 100 dV overall vs. what ejecting straight from Kerbin would have. It's lining up all the rest of it that seems truly daunting to me, although RIC's link should be very helpful for that. Another way in which I thought perhaps a Munar assist might be helpful is in terms of giving you another place to make use of the Oberth effect. If you have a really low TWR, that might allow you to split your boost between Kerbin and Munar periapses and thus enhance efficiency. However I have no idea how much the Oberth effect helps you boosting from 6000m above the Mun vs. 70km above Kerbin. Maybe some of the extra smart people around here could enlighten us on that point.

Edited June 9, 2015 by herbal space program

[Red Iron Crown]

Reworked my design a bit, now more capable and a bit prettier IMHO:

Over 3.5km/s of dV in orbit (and I might be able to do a slightly better ascent to squeak out a bit more), TWR lowish but workable. I'm tempted to try that crazy gravity assist route and attempt a return but my history with slingshots mostly involves them snapping back to hit me in the face.

[Starhawk]

Reworked my design a bit, now more capable and a bit prettier IMHO:

https://dl.dropboxusercontent.com/u/61004449/ksp/1.0/screenshot10.png

Over 3.5km/s of dV in orbit (and I might be able to do a slightly better ascent to squeak out a bit more), TWR lowish but workable. I'm tempted to try that crazy gravity assist route and attempt a return but my history with slingshots mostly involves them snapping back to hit me in the face.

Beautiful craft, Red!

It'll look good at Laythe.

Happy landings!

[spikes2020]

I made it! please see my submission http://imgur.com/a/9KUrP

*Under 20t

*Under 100 parts

*Every ton of payload brought and dropped off on laythe (payload may not be fuel or engines or anything that is actively used to propel the craft)

*Looks good (this is somewhat subjective but ill give +50 to anything that doesnt look bad as in exposed junk, RTGs on hull, that sort of stuff, i like sleek good looking craft).

47t

58 parts

2T of food oxygen and water for the trip

Looks good but the 6 containers of food.... but i needed them!

No docking port or anything fuel transfers =) 200 points?

Edited June 12, 2015 by spikes2020

[psyberduckling]

I've been messing around with Eve gravity assists to get to Jool.

For it to work you must have your periapsis inside Eve's orbit for the first assist, with a good trajectory you can get your orbit after the encounter close to a 1:2 resonance with Eve, to get a second gravity assist from Eve in order to reach Jool you need to shift your Periapsis inside Eve's orbit again (You can't get a good gravity assist when your periapsis is aligned with Eve's orbit). Burning retrograde at apoapsis until you get a second encounter is one way to do it, though if you're lucky you can probably use Kerbin, Duna or maybe Dres. A second gravity assist from Eve should be enough to get you well beyond Jool's orbit, with a bit of luck you should be able to get an encounter with Jool.

A formula for getting resonant orbits is:

a1 = factor^2/3 * a0.

a0 = semi-major axis of the body you're trying to achieve resonance with.

a1 = semi-major axis of your orbit.

And factor is the difference between your orbital periods.

T1 = T0 * factor.

Where T1 is your orbital period, and T0 is the orbital period of the body you're aiming for resonance with.

Semi major axis can be worked out via:

a = (periapsis + apoapsis + 2 * radius of the body you're orbiting) / 2.

For a 2:1 resonance you want your semi major axis to be roughly 1.59 * that of the body you're aiming for resonance with. I.E. your apoapsis should be close to 2.2 times your periapsis (your periapsis will be roughly equal to Eve's semi-major axis after a gravity assist).

You don't want exact resonance otherwise you'll have an encounter with Eve at the same place every time coming directly from behind it which makes gravity assist impossible.

Edit: An alternative to the retrograde burn at apoapsis is to perform a plane change at apoapsis before the second Eve encounter so that at your second encounter with Eve you'll either be coming from slightly above or below, and the gravity assist will work by cancelling your plane change.

Edit2: I tried the plane change thing for Eve, it's not worth it, you're better off burning retrograde at apoapsis to lower your periapsis inside Eve's orbit so that your next encounter has enough of an angle for gravity assist to be useful, less dV, and makes it much easier to line up the encounter especially if you manage to get close to 2:1 resonance.

Edited June 12, 2015 by psyberduckling