Laythe SSTO Design

[March Unto Torment]

Hey, everyone!

So, thanks to the tireless efforts of this forum, I've managed to reach a point where my main ship is approaching the stage of being 'ready to go' (still need to actually get the propulsion stage orbited and fuelled, but that's a problem for 1.1-era me).

I've got two landers built so far; one Tylo/Vall lander and one Bop/Pol lander. That covers four of Jool's moons.

However, I'm struggling with devising a fully-functional SSTO for Laythe. The requirements are as follows -

1. Must be capable of descending from a 100x100km Laythe orbit, flying for some fifteen minutes or so within Laythe atmosphere (long enough for me to find dry land), landing, and then ascending back a 100x100km orbit while still having 100m/s or so of dV for rendezvous operations.
2. Must be capable of transporting one Kerbal.
3. Must have a reasonable amount of RCS to allow for docking operations.
4. Must possess one 1.25m docking port (ideally the inline docking port, but I'm not overly picky).
5. Must weigh less than 40 tonnes fully-loaded (although that's an issue with being able to use my mediumweight launcher - it's not like I'm on a tight weight budget for this mission, as anyone from my other thread will know by now).

I tried modifying the existing 'Dove' SSTO for this purpose (basically by adding some RCS and an inline docking port in the middle of the craft), but I ended up with something that lacked enough fuel for my requirements and had huge centre-of-mass issues (when empty, the CoM was directly over the CoL, rendering the aircraft effectively uncontrollable). So that option's out.

Does anyone have any good tips for designing Laythe SSTOs? The main issue is that I can't really test them, since obviously, dV requirements aren't really linear for spaceplanes.

(Oh, and yes, I'd prefer it be a spaceplane, for the aforementioned reason of being able to fly in Laythe's atmosphere.)

Best regards,

 - March Unto Torment

[Starhawk]

Here's a shot of my Jool 5 ship with the Laythe lander prominently displayed.

This should fill all the requirements listed when fully fueled.  It can transport three Kerbals.

Happy landings!

[Foxster]

I don't have one to share but I have a couple of design thoughts. 

Does it have to have wings and does it have to be an SSTO? You can make a pretty light Laythe lander/orbiter. This is <14t and could be smaller...

This does mean you have to be pretty good at hitting a relatively small landing site on one of the islands though. 

The other thought is to take whatever craft you use craft down nearly dry and take along a disposable drill and convert-o-tron.

Edit: I just realised I do have a craft for you that should meet your needs, except for the docking and RCS (personally I would just rendezvous, EVA the crewman and abandon it in orbit) and I'm sure you can add those. My Starstreak SSTO...

I just tried it on Laythe and it de-orbits fine prograde with the air brake deployed without overheating. It also easily makes orbit again with loads of dV left over. It was a tad tricky to land but I got it on the third attempt. Masses 9.3t. 

Craft file: https://www.dropbox.com/s/3361yvvgjm87s71/Starstreak%20SSTO%207.craft?dl=0

(Craft was edited in KSP1.1, hopefully you either have that, or KSP can cope with reverting the file).

Edited April 9, 2016 by Foxster

[Wanderfound]

Pretty much anything that can SSTO from Kerbin can SSTO from Laythe (it's actually a bit easier due to the lower orbital velocity). A small single RAPIER ship could manage it, but you may find it easier if you go for a two-RAPIER one-nuke build. Up to speed on air-breathing mode, a quick burst of oxidising rocketry to raise the apoapsis, then circularise on the nuke.

The main difficulty for a Laythe SSTO isn't flight, it's landing. Ain't no runways there, the thinner air increases stall speed and the light gravity reduces braking force. So, a long and wide wheelbase, airbrakes, dragchutes and retrothrusters. Aim to get yourself stopped as soon as possible after touchdown.

[Foxster]

6 hours ago, Wanderfound said:

Pretty much anything that can SSTO from Kerbin can SSTO from Laythe (it's actually a bit easier due to the lower orbital velocity). A small single RAPIER ship could manage it, but you may find it easier if you go for a two-RAPIER one-nuke build. Up to speed on air-breathing mode, a quick burst of oxidising rocketry to raise the apoapsis, then circularise on the nuke.

The main difficulty for a Laythe SSTO isn't flight, it's landing. Ain't no runways there, the thinner air increases stall speed and the light gravity reduces braking force. So, a long and wide wheelbase, airbrakes, dragchutes and retrothrusters. Aim to get yourself stopped as soon as possible after touchdown.

+1 on that, it can be a real pig to land any aircraft on Laythe and especially less aerodynamic SSTOs. 

Thinking about, if I was doing it again with my little SSTO above, I'd probably stick two or three decoupleable chutes on and drift down the last few meters. 

[KerikBalm]

Pretty sure that the SSTO I'm packing in this mission meets those requirements... don't know about the mass though... its not super big though:

But it SSTOs from Kerbin as well, carries a full science complement and 6 kerbals, and can land on water or land.

I'm pretty sure it comes in under 40 tons.

8 tons of rapiers (i was thinking of switching one pair for whiplashes), +4 tons for the cockpit and cabin - 12 tons

mk2 bicoupler with fuel+2.29

mk2 LFO fus long + 4.57

2x FLT200s and 2x FLT100s + 3.375

2x LF fusalages: +4.5

Mk2 short cargobay +.25

mk2 inline docking port +.6

Science equipment, intakes, RTGS, etc + 1 or 2 tons?

Wings, pontoons control surfaces... +3 tons?

= 24.7 tons?

[March Unto Torment]

On 4/9/2016 at 9:37 PM, Foxster said:

Edit: I just realised I do have a craft for you that should meet your needs, except for the docking and RCS (personally I would just rendezvous, EVA the crewman and abandon it in orbit) and I'm sure you can add those. My Starstreak SSTO...

Beautiful!

Unfortunately, it's not loading in 1.0.5 ("data incompatible" or something), so I'm going to wait until Nertea's mods update to 1.1 before I'm able to use it. But that's not a problem, since I'm running the mission in 1.1 anyway (current operations around the mothership look more or less like a slideshow). So I'll probably be taking that, at least as my preliminary Laythe lander. However...

17 hours ago, KerikBalm said:

Pretty sure that the SSTO I'm packing in this mission meets those requirements... don't know about the mass though... its not super big though:

This thing is sweet. Massively overkill for my Jool-5 purposes, but given that my mothership will be repurposed as a Low Laythe Orbit space station overseeing operations there, I think I'll be taking that and modifying it some (take away the cabin, add some RCS and more room for internal cargo) for the purposes of supporting my Laythe colonisation efforts. Do you happen to have a .craft file I could borrow?

[numerobis]

You can test pretty well on Kerbin:

If you can make it to 2050 m/s (orbital) on Kerbin, you can orbit Laythe. In fact you can probably shave 50 m/s off that, because you don't need to fight as much gravity on Laythe at high altitude.

Your landing speed will roughly match: 20% less gravity, but also 20% less atmosphere so it's a wash.

[KerikBalm]

https://www.dropbox.com/s/77k3h8nh3a25ijp/SpaceMarines%20mk6.craft?dl=0

I tested the mk3 and mk4 versions more, which had the fl-t200 and 100 tanks switched (the pic of it on laythes ocean was a mk3 or 4, iirc). Its inline docking port is not at a "natural" center of mass... instead to be pushed as in that picture, the rear tanks were full, while the fore tanks were empty... I sort of used the small LF tanks in the pontoonsfor "trim" to get it just right.

It should SSTO from kerbin with about 150 m/s left, but to do that you'll need to get rid of most of the excess LF... don't launch with a full LF load unless you're going to fly around a lot and burn it off... but thats a good thing for laythe. as I already mentioned, I was considering swapping one rapier pair for turboramjets... it would give better cruise range, and also more thrust for takeoff, less mass for more closed cycle dV too.

I ditched the airbrakes, the brakes now activate the control surfaces on the wing to deploy in opposite ways, as well as the twin rudders. Its got an action group for the canard and hydroplanes to help lift out of the water/prevent nosing over (but that will still likely happen on the water). Its down to 1 braking chute from an earlier two.

Water landings are a bit difficult with a full fuel load, but manageable. It often noses over and ends up upside down, but it can br righted again.

In fact, it functions ok as a dynamic diving submersible:

I had started trying to design a smaller one, but the mk1 cockpit's heat tolerance is rubbish, I might try a 3 kerbal design with an inline cockpit though.

[AeroGav]

Sorry to be late to party.  I did build a mark 2 spaceplane a couple weeks back that can carry a set of IRSU gear and with enough range to get from Kerbin to Minmus,  Minmus to Duna, and eventually planet hop her way to Laythe.   It's got huge massive wing area and has a lovely low "no sweat" landing speed, even on the red planet -

https://onedrive.live.com/redir?resid=7003A8806D8A6B2C!719&authkey=!APpaxbR8Rs0uLHQ&ithint=file%2ccraft

 

 

The negatives are -

a) You will need TacFuelBalancer or similar,  otherwise the NERV engines will fail to draw from the wing tanks, where 90% of the fuel is.

b) I'm hanging a wing off a wing off another wing off an engine pre-cooler which is radially attached to the cockpit.   I've never tried flying it without Kerbal Joint Reinforcement, imagine it'd flap like a startled pigeon  without.

c) 9 years into her mission, she's developed engine trouble out on Laythe.   I may be able to work around this and get to Eeloo. See this tech support thread for details -  

Here's the build thread for the long range cargo SSTO I based her on, contains flight profile info and design rationale

 

[AeroGav]

By the way, if Jeb forgets to wind up his Kerbal Alarm Clock and misses the launch of the mothership, i have a monstrosity Laythe plane that could get there on its own.

https://onedrive.live.com/redir?resid=7003A8806D8A6B2C!727&authkey=!ALzHMCmQJPIc63Q&ithint=file%2Ccraft

 

After pressing the space bar another few times, you end up with the transfer stage...

The lander stage.  It's almost looking cute at this point.

Finally, the Laythe upper stage/Kerbin return stage.