Air Launch on Laythe?

[MedwedianPresident]

So...every schoolboy on Kerbin knows that Laythe has an atmosphere with oxygen that is useable for propelling your spacecraft with jet engines. So why not take this into advantage and use the atmosphere to launch things into Laythe orbit?

Basically it involves some sort of air launch aircraft (either White Knight style or hypersonic style) that uses the jet engines to propel itself to 10-12 kilometres and accelerate to 600-700 meters per second. The aircraft carries a payload - either a small spaceplane or a rocket - which is then separated and ascends into space using first a solid rocket booster and then it's own engines.

Any thoughts on that? Did you do that before?

[SSSPutnik]

I've used jets for initial launch almost all the way to orbit. Kicked in nukes when at high enough altitude.

Its pretty common.

[Skorpychan]

I've toyed with jets as a first stage on Kerbin, but they're more trouble than they're worth for a decent payload.

With Laythe's lower gravity, it may well be worth a shot. My lander designs for there are going to rely on Rapier engines, however, because mode switching.

[MedwedianPresident]

I mean not the first stage of a rocket or lander containing jets; i mean the rocket being launched FROM an airplane on laythe.

[Kasuha]

You don't have a VAB or launchpad on Laythe. You can only launch things that you delivered there previously. Bringing a complete multi-stage rocket or attaching some kind of payload to a lifter on ground just because you want to launch it certain way does not have much sense, it is better to come with single stage design which can land and return to orbit.

Apart of that, Laythe has the same property as Kerbin: untracked craft too far away in atmosphere disappears. So you would probably have hard time keeping both your plane and your rocket.

[MedwedianPresident]

Hm...yeah...maybe you could launch from a suborbital spaceplane like the Lynx? I mean; you quickly circularise the orbit of your main payload without letting the spaceplane touch the atmosphere; then you land the spaceplane.

[cantab]

SSTLAB - Single Stage to Laythe and Back - has been done. So this should certainly be possible.

[MedwedianPresident]

I mean definitely not SSTLAB. I mean that a large cargo spacecraft brings several medium spaceplanes to Laythe's surface. The medium spaceplanes then can be used to bring stuff into orbit and then land on laythe again.

[cantab]

Indeed. What I'm just saying is that if you can get to Laythe and back to Kerbin on a single stage, you can certainly get to Laythe and back into Laythe orbit on multiple stages.

You should save fuel if you use a carrier aircraft compared to an SSTO. I suggest using liquid fuel only for the rocket section, not solid boosters, that way you can refuel it more easily, though you could dock replacement boosters if you like. A reusable spaceplane/rocket and carrier aircraft would do well for Laythe operations I reckon.

[Dispatcher]

Since Laythe has lower gravity, higher air density and lower O2 content, I think those are trade offs which allow reasonable Kerbin testing prior to launching Laythe missions. These pics are of my state of the art for Laythe.

The first image is of the Lander/ Return vehicle and Rover Boat posing on the launch pad:

I've successfully deorbited them using parachutes only. The image shows them connected, but I actually separate them during the deorbit process. Each lands separately. Each will "land" on land and also successfully splash down; desirable given Laythe's water to land fraction. The Lander remains upright, ready to launch. The leg girders separate once the Lander clears the surface, followed by the jet assemblies, outer tanks and aerospike assemblies once in orbit. This is due to the Lander being a return vehicle to Kerbin (using an LV-N); so this is definitely not an SSTO in the pure sense. It achieves orbit with more than enough dV for a Kerbin return. I might be able to asparagus stage the outer tanks, but right now they are "onion" staged. The science group at the front of the Rover is primarily for balance. Kerbals can do EVAs and collect science prior to their being detached in Laythe orbit, prior to deorbiting. In the version the pic was taken, a Goo canister fell off, but that was later fixed.

The Rover Boat does well anywhere, using jets for water propulsion:

The third image is not the entire mission package. It includes the Lander, Rover and the Kerbin-Laythe transfer stage. The single LV-N was removed for this phase of structural testing.

The Transfer vehicle uses asparagus staging for the lateral tanks. At this point, I'm either going to need to make a WhackJobian launch vehicle to attain Kerbin orbit or move into the realm of docking and orbital assembly.

As others are suggesting, if you are wanting a Laythe analog of an orbital workhorse, it should be very doable.

Edited March 16, 2014 by Dispatcher

[FREEFALL1984]

My first stage always uses jets, my current lightweight lifter has enough guts to launch a 20 ton payload in to a 75km orbit then transfer to 120km orbit adjust inclination and dock with my station with about 400dV left over, The full vessel including jets and jet fuel AND the 20 ton cargo only weighs in at 89tons, This is with me performing the maneuvers, so it includes for my very high 14km gravity turn (it's only that high because I'm terrified I'll get hit when jettisoning my jets so I keep vertical until I stage if I grew a pair and did an early (5km and 40 degree) gravity turn and burned more of my jet fuel I could probably do it with 900dV left over. But it means I don't actually burn my first stage until I hit 14km, saving a hella lot of dV. And in fairness I tend to bring about 3x more fuel than I need in my jets and ditching 70% full jet tanks.

[cerberusti]

The oxygen atmosphere is very helpful.

This craft is 4 kerbals and a full set of science gear (including a lab) to laythe and back in a single stage and 224 parts:

http://steamcommunity.com/sharedfiles/filedetails/?id=239385512

You would probably need to gain orbit before releasing the payload, but that is very easy on laythe. You can get orbital velocity and a high ap before you cut the jets, so any sort of vacuum engine will do.

Might be useful if you have a base there, since you can supply a lot of jet fuel very easily.

Edited March 17, 2014 by cerberusti