All Purpose Lander

[Umlüx]

i am working on an all purpose lander for planets with atmosphere and moons. it will be the lander of my new interplanetary mothership (in progress) and should be able to land and return from every planet and moon except eve and tylo.

planned features:

wings for unpowered atmospheric descent

vertical and horizontal landing capability

RCS and docking port

this is my latest version. uses B9 RCS ports, KWR Vesta VR1 Engine, procedural Wings and MJ.

craft

now.. the price question is: how much dV is needed? i found some dV maps but seems i can't get the exact numbers for landing and returning from them.

i.e. http://i.imgur.com/NMmgbVH.png but i think the orbit values are only for intercept and circularisation?

Edited August 26, 2013 by Umlüx

[Psycix]

You need this much delta v:

Landing and ascending take the same amount of DV unless you aerobrake on landing in an atmosphere. Otherwise, try lithobraking!

Edited August 26, 2013 by Psycix

[Tw1]

Nope, the ones in the middle of the planets are the numbers to launch or land.

The basic idea would be to take the highest delta V requirement, double it, then add a bit more for mistakes, and for orbital maneuvers. Not counting Eve, Jool, Tylo, or Kerbin, the highest is Laythe.

With its atmosphere, you could just glide to a landing, reducing the need a lot. But you need to deorbit and aim. Some of the aiming could be done with the mothership, thought.

Then you just need the take of value in atmospheric delta V, on top of that.

One thing though: To use those values, you must land with the most efficient technique.

Looks like you need just a little more.

Disclaimer: I have not yet attempted a full grand tour. This advice is based on theory only.

[Umlüx]

are those values for landing or for starting?

edit: ah. you need the same dV to land and to start?

planets and moons with an atmosphere will be easy. i can deorbit with rcs and glide/parachute down. the problem are bigger moons like vall.

Edited August 26, 2013 by Umlüx

[capi3101]

Those values are for both; it takes as much to land as it does to start, provided the planet doesn't have atmo (if it does, you can use chutes and save yourself some delta-V). For example, it takes 640 to land on the Mun, and another 640 to take off again, so you want to plan for 1280 or greater in the lander.

Basically, if you can make a lander design that has 5600 delta-V after it's launched from Kerbin, you should be able to visit any other world in the system except for Tylo and Eve. If you build it with 6140 for greater, you can visit Tylo too.

Here's what I'd do: design a family of landers, ones with variable amounts of delta-V. Build your Tylo lander first and start removing elements for visits to other worlds. Better yet, consider replacing elements you remove with payloads of equal mass - things like packing rovers or sensor probes. You know, add stuff to do once you arrive at your destination - it's usually an awfully long way for Jeb to just get out, stretch his legs a bit, plop down a flag and then begin the long journey back.

That Gilly figure is not a typo - you can launch and land on that sucker with RCS thrust only. Provided you can get an intercept first, of course...

[Umlüx]

but wouldnt you need more dV for a Laythe return because of atmospherical drag?

[Rhomphaia]

but wouldnt you need more dV for a Laythe return because of atmospherical drag?

The figures for bodies with an atmosphere are rough estimates for take-off, and account for atmospheric drag with a fair amount of leeway for a non-optimal ascent

[Dravin]

but wouldnt you need more dV for a Laythe return because of atmospherical drag?

Edit: Looks like the figures take that into account.

[Umlüx]

ok thanks!

[Burninate]

You need this much delta v:

Landing and ascending take the same amount of DV unless you aerobrake on landing in an atmosphere. Otherwise, try lithobraking!

I've seen this a number of times - but I'm curious - what happens if you bypass circularizing LKO and simply raise apoapsis to escape velocity?

[capi3101]

Most of that 4550 is spent in the ascent; covers not only the amount necessary to achieve orbit but the gravity and drag losses. An ascent to escape velocity therefore oughta require somewhere in the neighborhood of 5500 m/s of delta-V to achieve.

Short answer: shouldn't make a difference at all...

[Umlüx]

i decided to stick to the good old lander-can design and scrap the wings. i easily got some 3500dv out of it. should be enough for laithe.

after that. i launched my new interplanetary ship, the KDSS Rhea. it has about 5400dv and can be refueled in orbit. the only thing is.. i forgot to make the probe carrier reloadable...

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[Specialist290]

I've seen this a number of times - but I'm curious - what happens if you bypass circularizing LKO and simply raise apoapsis to escape velocity?

The long and short of it is, the most efficient way to reach escape velocity works on the same principle as the most efficient way to get into orbit, so the actual delta-v cost would be about the same whether you stopped to circularize first or did it all in one continuous burn.