Laythe SSTO possible?

[m4rt14n]

Is it possible to make a spaceplane SSTO that can fly to Laythe, land, reorbit and back? With no mods, besides mechjeb without refueling. How much dV would it need? I'm trying to make one that holds 3 kerbal in a 3-man cockpit, but can't seem to get enough dV...

[capi3101]

Hmm...it's not something I've done personally, but I see no reason why it couldn't be done. So...the first thing you need to consider is that once it's in space, your spaceplane is a rocket. So you treat it like any other rocket...to the Delta-V map!!

680 LKO to KSO

180 KSO to Mun

70 Mun to Minmus

20 Minmus to Kerbin Escape

130 Kerbin Escape to Duna

480 Duna to Dres

370 Dres to Jool

270 Plane Change

0 to Laythe (aerobrake at Jool and/or Laythe - muck up a Jool aerobrake and you'll need 1880 to get back out there again)

780 LLO to Laythe Escape

290 Laythe Escape to Laythe

310 Laythe to Vall

220 Vall to Tylo

180 Tylo to Bop

60 Bop to Pol

160 Pol to Jool Escape

160 Jool Escape to Kerbin/Jool Transfer

0 back to Kerbin (aerobrake)

So, your plane would need 4,360 m/s of delta-V just for the rocket bit to get to and from Laythe in the optimal case - designing for 5,500 would give you a safety margin. It would also need to be carrying enough fuel for the 4500 launch from Kerbin and the 3200 launch from Laythe; so you want to be carrying around enough jet fuel for about two Kerbin takeoffs. I say that; you might want to get someone with more experience with Laythe flight helping you out there.

Anyways, those are the basics.

[palioxis1248]

, although it uses airhogging, which I find a little cheatsy. I'm gonna take a shot in the dark and say it takes about something like 7 kps, if you use aerobraking and all that.

EDIT: Didn't see that^. Please ignore the delta-v figure.

[Geschosskopf]

Laythe is about 3/4 of Kerbin in terms of what it takes to get from ground to orbit. So if you make an SSTO that can get up from Kerbin, you can be pretty confident it will also work on Laythe in terms of delta-V, intake air, fuel ratio, etc. You run out of air lower down at Laythe but OTOH the gravity is less and the atmosphere doesn't go as high so this sort of balances out. Getting the thing to and from Laythe is the same as for any other ship: you just need a transfer stage, or tug, or something. Some folks use ion engines for the transfer although burn times are huge that way. Better to dock to a transfer tug IMHO.

The major fly in the ointment with planes on Laythe is finding a place to land. Laythe doesn't have much land to begin with, what it does have it divided up into tiny islands, few of these islands are on or near the equator, and most of the ones that are are pretty hilly. So basically, short runways. Thus, you have to give your plane a lot of wing for its size, so it can fly very slowly (especially considering the thinner air) to land in short distances. Also, the further from the equator you stray, the more delta-V you need, which makes the plane bigger, which means it needs even more wing.

Now, that's stock. You can make life a lot easier for yourself if you put some Firespitter pontoons on the plane so it can land in the water. Then you have the entire circumference of Laythe as a runway and don't have to worry about STOL performance. You could also, I suppose, make stock pontoons out of like radial intakes but I've found these to be way too bouncy to be safe.

[John Crichton]

Yup, possible: LINK

Not easy though, especially without part clipping. It gets a lot easier with the Interstellar mod...or Kethane.

Here's some inspiration if you want to try mods:

1) SSTO plane with truckloads of deltaV left after reaching Kerbin orbit. You could probably make the ascent more efficiently too...I'm not an expert pilot. Carries 1 Kerbal...2 if you count the exterior hardcore seat.

2) SSTO lander with even more deltaV...and easier landing. It uses plasma thrusters and can refuel using Kethane...can land on most planets/moons and it's so easy to fly, I'm currently using it as my "post pub session" craft. It's very forgiving and you can mess up your nodes without having to worry too much about deltaV. Carries 2 Kerbals...but I just added 3 exterior seats so I can use that SSTO to rescue stranded Kerbals everywhere (there's a lot of them).

PS: I do realise I went a bit overboard with solar panels on my SSTO lander...it was late and I had a few beers too many. Hardly impacts weight though, so I'm too lazy to remove them. The craft has a docking port at the bottom, so I can always use the extra power for whatever I dock it to.

Edited March 13, 2014 by John Crichton

[m4rt14n]

I love those solar panels and lighting. Looks like those squids from ME3.

[John Crichton]

I love those solar panels and lighting. Looks like those squids from ME3.

Thanks...the nav light mod is cool and doesn't use a lot of resources. It also doesn't improve performance, so if you don't want to use any performance-enhancing mods, you can still get that one.

Forgot to switch on the lights on the 1st SSTO...it has Rastafarian colours

Took me 4 trips to the Mun and back to get the 2nd SSTO like I wanted it. I first forgot the Kethane scanner, then Kethane tanks (duh!), then fit my miners too high so they couldn't reach the ground (lol) and only managed to successfully land and mine on the 4th attempt. Good times

It has a ridiculous 40k DeltaV and refueling capability...and a TWR above 1 on Kerbin's surface. Not exactly something you'll manage with stock items. I just wanted something to cruise around leisurely when I'm not in the mood for a difficult challenge. Good training craft if you just want to learn about transfers...you can mess up (multiple times...as I usually do) without having to start over. It's also only 100 parts (exactly!), so a hamster-wheel-powered PC should be able to handle it.

Disclaimer: I'm using a fuel mod because plasma engines don't need oxidizer...so I removed oxidizer in favor of liquid fuel for all fuel tanks. Tanks aren't full when leaving Kerbin to keep TWR above 1. I refuel on low-grav moons before longer interplanetary transfers. By the time I reach destinations, my fuel is low enough to push my TWR up to landable levels again...

Edited March 13, 2014 by John Crichton

[m4rt14n]

All my interplanetary ssto has like .17-.30 TWR lol!

Also landing shouldnt be a problem with mechjeb, CMIIW you should be able to just point to the landing spot using the guidance module.

Edited March 13, 2014 by m4rt14n

[John Crichton]

All my interplanetary ssto has like .17-.30 TWR lol!

Also landing shouldnt be a problem with mechjeb, CMIIW you should be able to just point to the landing spot using the guidance module.

You can't build an interplanetary stock SSTO with much more than that...at least I never managed to do so.

An alternative approach would be to build a nice SSTO that can land and take off from Kerbin...and then an interplanetary ring for it. Some examples of that have been posted on the forum.

[capi3101]

Alrighty...I'ma gonna try to hammer this out real quick-like.

The standard guidelines I go off of for any spaceplane are:

*1 turbojet per 9-12 tonnes of payload (12-15 total tonnes of craft), depending on how much airhogging I'm willing to commit. In this case, we'll go with strong airhogging for the twelve figure. 1.2 tonnes per jet.

*Nine ram intakes per jet. That's 0.09 tonnes, but we'll round up to .1 to make the numbers easier to work with.

*200-250 units of liquid fuel per jet. Since we want to do both Kerbin and Laythe takeoffs, we'll double that figure to 400-500 units. I'll recommend a combination FL-T800 and FL-T200 with the oxidizer drained off; that should have a full mass of 2.875 tonnes all told.

*Three pairs of swept or delta wings per eighteen total tonnes of craft. Say swept wings for 0.3 total tonnes.

That's 4.475 tonnes of flight equipment that will be deadweight in space, let's say. You can have up to fifteen total tonnes of craft on that, so about 10.525 tonnes that's just rocket.

Alright. So we want a Mk3 Cockpit (3.5 tonnes), a Large ASAS unit (.2 tonnes), and let's go with two nukes on a Biadapter (4.6 tonnes), so 8.3 tonnes of total paywad. What we can do is up the deadmass for more and more sets of flight equipment, looking for a delta-V target of 5500 at 800 Isp, until we get something that's within the flight tolerances of the flight equipment - like this:

1 set, 12.775 tonnes payload, 5500 delta-V @ 30 FL-T100 equivalents, total mass 29.65 tonnes (too much; you only have enough engine for 15 tonnes)

2 sets, 17.25 tonnes payload, 5500 delta-V @ 41 FL-T100 equivalents, total mass 40.3125 tonnes (too much; you only have enough engine for 30 tonnes)

3 sets, 21.725 tonnes payload, 5500 delta-V @ 51 FL-T100 equivalents, total mass 50.4125 tonnes (too much; you only have enough engine for 45 tonnes)

4 sets, 26.2 tonnes payload, 5500 delta-V @ 61 FL-T100 equivalents, total mass 60.5125 tonnes (close enough for jazz)

So you'd need four sets of flight equipment - four turbojets, a total of 36 air intakes, and the fuel. There was some redundancies built into the wing set - twelve wing pairs gives you enough lift for a 72 tonne craft, so if you wanted to you could ditch two pairs or so. The added mass could be applied to things like control surfaces and the like.

61 FL-T100 equivalents? That's three FL-T100s shy of an orange tank in the center, so you could just go with an orange tank, but then whether or not you'd have enough jet thrust would be questionable.

It'd be interesting to put this together and see how well it worked; might have to do it myself.

[Geschosskopf]

All my interplanetary ssto has like .17-.30 TWR lol!

Also landing shouldnt be a problem with mechjeb, CMIIW you should be able to just point to the landing spot using the guidance module.

MJ's spaceplane autopilots do not work. Period. You have to fly the thing down yourself. And even if MJ's autopilot DID work, the fact still remains that the plane's flying characteristics are set by your design, not MJ's autopilot. So you still need to make it so it can fly very slowly to be able to hit and then stop within a potentially very short landing field.

[John Crichton]

MJ's spaceplane autopilots do not work. Period. You have to fly the thing down yourself. And even if MJ's autopilot DID work, the fact still remains that the plane's flying characteristics are set by your design, not MJ's autopilot. So you still need to make it so it can fly very slowly to be able to hit and then stop within a potentially very short landing field.

Agreed. Although, you can use MJ to land and simply disable it in the last moment before pointing the landing gear in the right direction.

[FenrirWolf]

This is the plane I used to get to Laythe and back with no need to refuel

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Jeb kinda broke the first plane to Laythe upon landing, but a replacement fitted with a probe core was able to fly out and take him back home, where his piloting skills were shown not to have changed much when it comes to landings.

I had to do a good bit of warping for things to align for that Tylo slingshot too. But that's easily one of my favorite pics I've taken since I set it up just by eyeballing things until they fell into place.

Edited March 13, 2014 by FenrirWolf

[Claw]

This is the plane I used to get to Laythe and back with no need to refuel

This looks like something I've been working on, though I haven't had the guts to go to Laythe with it.

[John Crichton]

Decided to take my SSTO lander thing to Laythe. Bill and Jeb are enjoying the flames during my Jool aerobreaking.

Started on Kebrin, refuelled at the Mun because of low gravity...then did the transfer to Jool without waiting for a proper window. Next stop, Laythe.

Btw, some guys in here are doing good calcs

First time visiting Jool.

The way I'd design your Laythe stock SSTO is to start out with only what you rally need...even if that means it might not look "pretty".

Edited March 13, 2014 by John Crichton

[m4rt14n]

Dont use the spaceplane landing guide in MJ, use the landing module to point to a general area. Once it made all the burns outside atmosphere, land it yourself. Not perfect but it works.

Edited March 14, 2014 by m4rt14n

[capi3101]

First iteration of the plane...

I didn't do a full ascent on account of there being other things I wanted to get accomplished in the game last night. I was just amazed it made it off the runway on the first go without careening off to one side or flying straight into the drink - empennage helps. The CoL is still too far back, though; had to sit there holding the S key the whole time. It never did do better than 20 degrees of AoA, either, which means I'll need to add either more wings and/or more thrust at some point. But it's a start.

EDIT: I say it never did better than 20 degrees AoA - my screenie looks like I've got 15...

[immelman]

There are a number of examples in boolybooly's spaceplanes thread, including mine

I Second the point about finding a good place to land. I found using a parachute as a drouge helped a lot....

[raygundan]

This little guy is capable of single-stage to Laythe and back at about 12.5t on the runway, with a full science package:

I haven't *quite* finished the whole flight process-- I've flown it to Laythe, landed, taken off, made the transit back to Kerbin, and parked it in a stable orbit before I had to call it a night, so it hasn't actually *landed* yet-- but I've got ample dV to deorbit, and it's pretty forgiving to land. I may not hit the runway (or only hit it briefly at a funny angle), but I'll definitely be in the grass by KSC.

All stock parts except MechJeb, two intakes, one RAPIER engine and two ion engines, and just the single pair of wings, x-tail, and two canards, no hidden clipped-in triple wings or anything.

Edited August 1, 2014 by raygundan
more information

[James_Eh]

Sigh. I've spent a couple of hundred of game hours on this exact quest, with the plane heading up towards 100T and counting, only to see these beautiful creations on display. It is often humbling when you see what others have built.

Cheers to all of you talented folks! I'm heading back to the lumbering mess of a ship that is about to aerobrake at Laythe.

[O-Doc]

Sigh. I've spent a couple of hundred of game hours on this exact quest, with the plane heading up towards 100T and counting, only to see these beautiful creations on display. It is often humbling when you see what others have built.

Cheers to all of you talented folks! I'm heading back to the lumbering mess of a ship that is about to aerobrake at Laythe.

Don't try to brute-force the problem. Get to LKO as efficiently as possible. Don't put anything on your craft you don't need. The key is intakes and wings, or go with ION engines for transfers.

I've got over a dozen SSTOs which match this criteria in my hanger, alot of them are available in my catalogue download.

[bsalis]

Yes, very possible with stock parts. You can do it with LT-Ns. Though a small craft using Ion engines is pretty neat. People were doing Laythe returns even before they were buffed. It's actually pretty easy now with Ions.