Reusable Atmo Lander

[Gargamel]

I'm having trouble coming up with a design.   I have a large mother ship that carries some smaller ships.  I want a lander that will be capable of landing on atmospeheric bodies (Duna, Lathe, Eve maybe not so much :)).  It needs to be small and simple.  It's probably that I'm stuck in a design paradigm with this, and I need ideas.  I'd prefer all mono prop for propulsion, as it reduces part counts and size, I am using Near future, so it has some really nice mono engines. 

But How do I get a heat shield, engine, and docking port all inline at the extremities of my ship?  I'd prefer an inline docking port as the "docking bay" area of my mother ship is kinda confined, and I find inline docking easier to build.  I also want the heat shield to be resuable, is there a mechanic for re upping the ablative material? 

I could use the inflatable heat shield with radial engines.... hmmm..... ideas?

[W. Kerman]

10 minutes ago, gargamel said:

I'm having trouble coming up with a design.   I have a large mother ship that carries some smaller ships.  I want a lander that will be capable of landing on atmospeheric bodies (Duna, Lathe, Eve maybe not so much :)).  It needs to be small and simple.  It's probably that I'm stuck in a design paradigm with this, and I need ideas.  I'd prefer all mono prop for propulsion, as it reduces part counts and size, I am using Near future, so it has some really nice mono engines. 

But How do I get a heat shield, engine, and docking port all inline at the extremities of my ship?  I'd prefer an inline docking port as the "docking bay" area of my mother ship is kinda confined, and I find inline docking easier to build.  I also want the heat shield to be resuable, is there a mechanic for re upping the ablative material? 

I could use the inflatable heat shield with radial engines.... hmmm..... ideas?

A word of warning- All those places have vastly different surfaces, and different requirements in terms of TWR and their delta V. 

People build thousand ton behemoths to get off Eve with reusable landers. I can make a 16 ton Laythe spaceplane. There is no one craft that can be optimized for all of those planets/moon that would fit in a Mk3 cargo bay.

 

Sorry, W. Kerman 

[Lunar Sea]

hmm, ok a couple things -

it takes a lot to fully ablate a heat shield, especially the bigger ones. you could in theory reuse it several times, especially if the craft is entering from only low orbit

but, in that case you probably don't need a heat shield at all, even at normal difficulty. 

 

And yes, what W. Kerman said - the requirements for the different atmo bodies are such that a single-craft solution is not practical. 

[Gargamel]

Well, I'm not planning on landing on Eve, I know the difficulties.    But I will be adding an interstellar mod eventually, so there will be more targets with atmospheres eventually. 

And it's not an internal bay, it's a niche in the design of the craft that allows for other ships to dock there.   I already have 4 ships docked in it, I'll probably be getting rid of the smaller 2 man vessel in lieu of this one.   And I don't want a space plane.  

DV requirements aren't that much of a concern, as it will be low orbit landings and launches. 

[nascarlaser1]

If your not against mods on this idea, you could us KIS and KAS.  On your mothership, bring at least 3 heat shields per lander (that way in an emergency you will always have some), and once you use a heat shield to its maximum (or however close to maximum you feel safe doing ), just grab an engineer, take off the used heat shield, and slap on a new one. If you do not want to use mods, you can always attach docking ports to top of your lander. This way, you can replace the  heat shield via the docking port, or when the landers are in storage, you just take the heat shields off and dock it to the rest of your ship .

[juanml82]

You don't need a heatshield for Duna and I think you may skimp on that for Laythe as well. With that out of the way, you can place an engine at the bottom and a docking port at the top. However, will you have enough dV with monoprop engines? My first idea would be to use aerospikes.

[Razorforce7]

There is a way to do it without heatshields and go the SpaceX ITS way which I've replicated on some of my craft which I will explain here.

Make your lander into a somewhat cyllindrical rocket (like most rockets are)
Then radially attach wing surfaces to the outer fuselage as if you were strapping wings onto a aicraft.
Move/rotate : tool them to preferred location which is where the CoL is just under the CoM and make it look nice (or not if you like trash art)
If you have enough reaction wheels or rotational RCS torque you can aerobrake like i.e. a spaceplane would by maintaining a high angle of attack.
You will basically aerobrake a rocket (lander)  vertically through the atmosphere. (like the ITS)

This way of aerobraking is much more effective everywhere. The only drawback is that on most interplanetary captures you will need to do a decceleration burn.
But from your post I take it you have a mothership which surely is in a low orbit. So you wont have that problem then I take it.
 

 

[Gargamel]

35 minutes ago, juanml82 said:

You don't need a heatshield for Duna and I think you may skimp on that for Laythe as well. With that out of the way, you can place an engine at the bottom and a docking port at the top. However, will you have enough dV with monoprop engines? My first idea would be to use aerospikes.

with the NF engines, my smaller lander has around 2k DV in it, and the 7 seater has about 1400.  I'm a little worried about TWR though once on the surface. 

I'll take a look at The aerospikes too, I have plenty of LFO on the ship too, as that's what my RCS thrusters require. 

Edited April 5, 2017 by gargamel

[Noobton]

I'm moving this to Spacecraft Exchange, so everybody can post their crafts.

[Heckspress]

check out Cupcake's landers, maybe??

[Gargamel]

So Here's what I came up with:

 

Heat shield on the bottom, chutes for braking, 4 radial Thuds for power, nose cone is also a tank, 2200ish DV, 1.6 TWR on kerbin surface. 

 

Successfully tested a landing and ascent on Duna.  

[Rune]

You didn't ask for much, did you? The problem is, Laythe has a gravity well almost the size of Kerbin's, and Duna has no oxygen.And of course, forget about single-staging Eve. So, basically, what you need for this is a Kerbin-class chemical SSTO. And good luck squeezing that into a cargo bay! Here is one example of what you are looking at:

The first one is my Heinlein, and the second one the Lackluster. They have the particularity of needing no heatshield, since the can reenter either nose-first stably (and that shielded docking port is unbelievably tough), or switch to a tail first attitude with RCS on the high atmosphere, or airbrakes and chutes lower down. Took quite a lot of finagling to get cose-to-stable enough to do that, tough.

 

Edit: what do you know, I already had one that fits the bill. Pretty simple to reverse-engineer, no clipped parts at all, and the docking port is balanced on the other side with a fuel cell. 18 Parts, single seater, single spike. Thoroughly untested, but it has the numbers to have me pretty sure it'll do the job. Maybe with an additional parachute.

 

Rune. I've never needed a heatshield to return form low orbit.

Edited April 6, 2017 by Rune

[septemberWaves]

Near Future Spacecraft does add monopropellant engines, but the problem you're going to encounter if you try to use them anywhere with a denser atmosphere than Duna is the fact that they're vacuum-optimized because they're designed for upper stages and orbital maneuvering systems. You're not going to be able to make a Laythe-capable vehicle using OMS engines as the main propulsion system. As for Eve, well, the only monopropellant engine I know of which produces enough thrust at Eve's surface to lift much more than the engine itself is the monopropellant aerospike from RLA Stockalike. But you're not going to be making an Eve-capable SSTO any time soon using that engine, it's just too impractical and probably impossible.

So, discounting the possibility of an Eve SSTO and also the possibility of using monopropellant engines in a dense atmosphere, your best option is to create a Kerbin-capable chemical SSTO, as has already been said by others in this thread. A Kerbin-capable chemical SSTO is also an SSTO anywhere other than Eve and Tylo (provided you refuel it in orbit), but even then you'll have one hell of a hard time fitting it in a Mk3 cargo bay. I have actually created a lander that fits this description and fits in a Mk3 cargo bay, but it only carried a single kerbal and no equipment, and it relied on several parts mods in order to fit all of the tanks that were needed (stock-balanced tanks but still modded); plus, it had to land on very flat terrain to avoid tipping over, because the constraints of the cargo bay meant that a tall lander was necessary.

Also, the only place where you'll need a heat shield for atmospheric entry from low orbit is Eve, and it's already been pointed out that an Eve SSTO is impractical (and one that fits in a Mk3 cargo bay is most likely impossible). Anywhere else and you'll be fine unless you plan on entering from a highly-elliptical orbit. And you won't want the inflatable heat shield on any vehicle that has to ascend through an atmosphere again, because you'll have to jettison the heat shield and that means the vehicle is no longer fully reusable.

[Gargamel]

Why is it people refuse to read an entire thread, especially a short one, before responding?    All that leads to is fracturing of the discussion. 

[AeroGav]

7 hours ago, eloquentJane said:

A Kerbin-capable chemical SSTO is also an SSTO anywhere other than Eve and Tylo (provided you refuel it in orbit), but even then you'll have one hell of a hard time fitting it in a Mk3 cargo bay.

QFT.

BTW , I am not sure if the OP stipulated it must fit inside a cargo bay ? I read that to mean he wanted the craft to have an inline clamp o tron for mating to his mothership , though i can see why having all your landers fit within mk3 cargo bays in the main body would be easier (centre of mass issues, the bane of my rocket experiments).

A spaceplane design would be much easier if there were radial booms sticking out from the mothership,  which an SSTO can hook on to with its fuselage mounted in-line clamp o tron.  Then you're not restricted on wingspan.

I've started a game with interstellar tech installed, the engine i'm looking forward to is the thermal turbojet.  It basically operates as a nuclear powered jet engine (uses no fuel at all) in any atmosphere , even if it contains no oxygen (eve, duna ).  When the air gets too thin,  it switches mode to operate like a nuclear thermal rocket engine.   I'd probably run it off ammonia since it's storable.

My SSTO are usually interplanetary, have NERV engines and often in fact liquid fuel only.   I don't have any experience of building motherships,  but if i did i'd probably use the nuke engines of my spaceplanes to help push the mothership.  For example, you could have two SSTO mounted either side of the main body and you've got a balanced pusher config.

My smallest LF only SSTO - can reach Minmus.  Would be able to take off from Duna and Laythe NP.    I built this thing as low tech as possible,  for an interplanetary shuttle i'd upgrade to RTG generators,  Big S wings & strakes (get rid of the fuel tanks either side of cockpit), add an inline dock adapter and beef up the landing gear.

Spoiler

my first mothership - pushed by a pair of these?

 

 

Edited April 6, 2017 by AeroGav

[sh1pman]

So what about Eve sea level SSTOs? Are they even possible?

[juanml82]

4 hours ago, sh1pman said:

So what about Eve sea level SSTOs? Are they even possible?

The question gets asked from time to time in the forums. Personally, I doubt it, at least with stock parts.

[Foxster]

8 hours ago, sh1pman said:

So what about Eve sea level SSTOs? Are they even possible?

No, they aren't - or not stock anyway. 

Even spaceplanes are marginal. You really need a rocket to punch up out of the soupy atmosphere quickly to lift even small payloads to orbit.  

[AeroGav]

32 minutes ago, Foxster said:

No, they aren't - or not stock anyway. 

Even spaceplanes are marginal. You really need a rocket to punch up out of the soupy atmosphere quickly to lift even small payloads to orbit.  

 

8 hours ago, sh1pman said:

So what about Eve sea level SSTOs? Are they even possible?

I managed a TSTO space plane with a Dart aerospike lower stage (lifts us to 15-20km) then upper stage is a nerv powered spaceplane.  Having wings allows the poor TWR of the NERV to be workable, the aerospike is needed to get to an altitude where the air is thin enough for the NERV to get good ISP.        Whilst that design wins in terms of bringing a large fraction of itself to orbit,  a multi stage expendable rocket could bring a kerbal back up for   the same total mass, because you can make the final stage tiny - Command chair , Oscar B's and a Spark.

With Interstellar, the dual mode nuclear turbojet (operates as a nuclear turbojet at lower altitudes, but can then switch to a nuclear thermal rocket when the air gets too thin looks like a winner, and it's not particularly high in the tech tree) 

[Rune]

2 hours ago, Foxster said:

No, they aren't - or not stock anyway. 

Even spaceplanes are marginal. You really need a rocket to punch up out of the soupy atmosphere quickly to lift even small payloads to orbit.  

Actually...

No, seriously, Eve SSTO is a no-go. It is theoretically possible to do it, form the tallest mountain, with the efficientest spaceship, for some definitions of "SSTO" and "recoverable". Now, doing it in a practical way by the average kerbal? That is the impossible thing (without mods).

 

Rune. But it's a horse people like to beat down repeatedly.

[septemberWaves]

Sea-level Eve SSTO? Doable in theory. Practical sea-level Eve SSTO? Not going to happen.

The discussion in this thread has somewhat diverged from the original topic towards the realm of Eve SSTOs. It's probably a good idea to get back to discussing the sort of reusable lander which the original poster is looking for (they did clarify in another post in the thread that they are not going to consider Eve).

[sdj64]

Here's a two seat lander that you might like.  The higher mass of the 2 man lander can needs two aerospikes, but it should do Laythe no problem.  It doesn't SSTO on Kerbin so you'll need to make a lower stage for it to send it up to the mothership.

Really anything with a shielded docking port on top will work well reentering forwards.  It's incredibly heat resistant and doesn't depend on ablator so it's fully reusable.

[THE NARWHAL]

Well, if you really wanted something that could SSTO off of, say, Duna, you could just use a mining craft capable of refueling itself. Although, it does somewhat limit landing sites.

[*MajorTom*]

On 06.04.2017 at 0:34 AM, gargamel said:

I'm having trouble coming up with a design.   I have a large mother ship that carries some smaller ships.  I want a lander that will be capable of landing on atmospeheric bodies (Duna, Lathe, Eve maybe not so much :)).  It needs to be small and simple.  It's probably that I'm stuck in a design paradigm with this, and I need ideas.  I'd prefer all mono prop for propulsion, as it reduces part counts and size, I am using Near future, so it has some really nice mono engines. 

But How do I get a heat shield, engine, and docking port all inline at the extremities of my ship?  I'd prefer an inline docking port as the "docking bay" area of my mother ship is kinda confined, and I find inline docking easier to build.  I also want the heat shield to be resuable, is there a mechanic for re upping the ablative material? 

I could use the inflatable heat shield with radial engines.... hmmm..... ideas?

Eve spaceships - always are behemoths, and if it reusable - it is modded behemoths . For Dune, Laythe you can make a simple nuclear propulsion winged SSTO / or SSTO with winged lander (tons of contructions in this forum) . So there is not 1 good AND simple construction for different atmospheres.

ps: and if you have are wings and mining module - you don't need reusable heatshield at all . 3200 for empty heatshield is normal temperature even for Eve gliding descent.

my one-year old Eve spaceplane (not reusable, but also not behemoth, atmosphere aerobraking and gliding, not need ablator in descent and about yor asking - you can use this idea for wing protection in your ships for Eve descent):

https://youtu.be/j2iwEXP0ooQ

 

[AeroGav]

Spaceplanes are difficult to integrate with motherships,  i'm discovering.     Wings don't fit in cargo bays.  Nose mounted docking ports are high drag.  Low lift and high drag does not make for a great spaceplane, especially one that needs to make safe landings on mulitple offword biomes.

I'm experimenting with this contraption,  uses inline clamp o trons.   The nerv spaceplanes act as the mothership's propulsion , when docked.  Problem is, docking is very tricky, even with translation thrusters, but i am out of practice.