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Laythe Crew lander design


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It's been a while since I've done a landing on Tylo, but according to the wiki, it takes around 2300 m/s to land, and about the same to take off. If you're taking up much more than that, you should look at your landing method.

I'd definitely do a multi-stage lander, as having sufficient TWR and delta-V will be difficult without staging. 

It makes sense to have a single ascent stage, and at least one descent stage. Keep engine weight as low as possible. There is no need for super-high TWR values (more than 2). When landing, remember that TWR only matters toward the end. If you can use a mod that tells you when to perform a suicide burn, that can save you a lot of wasted fuel.

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Tylo is by far the hardest vacuum body for lander design.
You know that.  You can design an uncrewed lander.

Are you sure you want a single vehicle that has i) a crewed lander AND ii) a separate rover AND iii) all the science gear?
Suggestions:
A.  A rover that can launch back to orbit.  Then the actual landing vehicle is a simpler uncrewed stage.
B.  A separate drone science-pack.  Since you have a rover you can drive to and meet the drone once your crew are down.

For an actual design - how many crew?

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1 hour ago, The Doodling Astronaut said:

Okay guys update I now have to build a better Laythe lander please help if you can!

Honestly, I've only used ever spaceplanes to move crews between Laythe surface & orbit.  Everything else comes down by parachute, maybe with some small landing engines.

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On 7/15/2019 at 1:19 PM, The Doodling Astronaut said:

I redesigned the lander and now the ascent stage has 4000 m/s. Is this enough

Yep, if it's reasonably aerodynamic.

5 hours ago, The Doodling Astronaut said:

Okay guys update I now have to build a better Laythe lander please help if you can!

Laythe is pretty close to Kerbin.  The gravity is a little lower, and the air is a little thinner at sea level, but it doesn't thin out as quickly as you ascend.  If you're going with a rocket approach, you can generally build like you would a Kerbin launch vehicle, but you can skimp  a bit on the TWR and total delta-v requirements.  Vacuum engines are useful lower in the atmosphere, but still not great at sea level.  You should try make your craft reasonably aerodynamic, but it's not as crucial as something like Eve.  Though since you'll be carrying the thing all the way from Kerbin, you'll probably want to go as light as possible.  If your craft can reach orbit from the launch pad on Kerbin, you should have a good safety margin for Laythe. 

The biggest problem I've found with a conventional parachute-assisted lander is getting it to either (1) land on one of the small patches of dry ground, or (2) be able to stay upright on a water landing.

Laythe is, however, a paradise for spaceplanes.  Finding a landing spot is much easier.  And a Rapier-powered plane can get you almost all the way to orbit on jets alone, with just a couple hundred m/s needed to circularize from a suborbital trajectory.

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Here's one quick idea/concept, but by no means optimized or the only possible architecture.  Notes:

  • The fuel lines are only to show accurate delta-v stats; you'd want to use crossfeed to reduce weight and drag.
  • This is way to get rid of the landing legs relatively quickly into your ascent.  You could also take it a step further and leave all the landing stuff on the ground, Apollo LM style.
  • You can SSTO in a rocket from Laythe, but you'll pay a mass penalty for it.   
  • Might be better to put the parachutes on the radial stacks, and a nosecone on the center, to save some weight/drag later in flight.
  • Can be modified for docking by putting a Jr sized port under the chute / nosecone.
  • I've chosen Sparks as they're appropriately sized for this small craft, and have decent stats in both atmo and vacuum.  The Cub from Making History would be a good fit too.
  • The solar panels aren't going to do a whole lot.  If you're bringing a probe core or otherwise expect to use more than a minimal amount of electricity, a fuel cell might be a better call.

 

XCR7tLI.jpg

Edited by Aegolius13
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I'd generally advise a Space Plane for Laythe because it's too hard to find somewhere to land otherwise.

However, a normal lander would work too, if you design it for a water landing. You'd want some way to ensure it stays upright after it lands in the water, and I'd definitely test it in Kerbin's water before sending it off. Treat Laythe as basically about 85% that of Kerbin -- any rocket that has about 85% of the delta-V and 85% of the TWR should be able to make it.

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11 hours ago, The Doodling Astronaut said:

Okay guys update I now have to build a better Laythe lander please help if you can!

Which has wrecked the thread as a source of information about Tylo landers.

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On 7/15/2019 at 9:19 PM, The Doodling Astronaut said:

SO I finished my laythe lander and flew the whole laythe mission did surface science then took off then it failed because it was 700 M/S short. Besides me saying REAAAAAAAAAAAAAAAT!!!! I redesigned the lander and now the ascent stage has 4000 m/s. Is this enough?

This is one of those hard to answer questions. 

If you are flying a brick to orbit and/or flying it badly then no.

If its a half-decent design and you can fly it reasonably well then yes. 

Pictures would help. 

Here's one way to do Laythe...

QmGvDLY.png

 

Edited by Foxster
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I have 4000 M/S of fuel on this assent and it isn't really getting there :(. If you have some way of the most efficient way of to get off laythe please tell.

This image has an empty alt attribute; its file name is image-2.png

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Nothing you can do to improve the aerodynamics of a craft in situ (without mods, anyway), other than modifying your flight profile.  You could try using a gentler gravity turn to get out of thick atmosphere quicker.  (This is probably good practice on Laythe vs. Kerbin, since gravity losses are lower but drag is material up to higher altitudes.

Also, that thing looks like it goes very, very fast.  If you hit too high of a speed to low, your drag losses will be much higher.  Throttling down might help.

 

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Well...

8 minutes ago, Aegolius13 said:

Nothing you can do to improve the aerodynamics of a craft in situ (without mods, anyway), other than modifying your flight profile.  You could try using a gentler gravity turn to get out of thick atmosphere quicker.  (This is probably good practice on Laythe vs. Kerbin, since gravity losses are lower but drag is material up to higher altitudes.

Also, that thing looks like it goes very, very fast.  If you hit too high of a speed to low, your drag losses will be much higher.  Throttling down might help.

 

So going really fast creates drag? It explains why my ascent works until 10km

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11 minutes ago, The Doodling Astronaut said:

Well...

So going really fast creates drag? It explains why my ascent works until 10km

Yep.  Drag is proportional to the square of your speed, with (I believe) some tweaking for transonic drag.  If you want to look at your drag info in more detail, you can use the console (alt-12), physics > aero > aeroGUI.

Drag is in newtons, as is thrust, so this can tell you what portion of your rocket is being wasted to drag.

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26 minutes ago, Aegolius13 said:

Yep.  Drag is proportional to the square of your speed, with (I believe) some tweaking for transonic drag.  If you want to look at your drag info in more detail, you can use the console (alt-12), physics > aero > aeroGUI.

Drag is in newtons, as is thrust, so this can tell you what portion of your rocket is being wasted to drag.

I'm getting closer. I missed circulation by 200 m/s and I will get there eventually

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7 hours ago, The Doodling Astronaut said:

@Foxster is this aerodynamic or possible to get off the surface it hurts to restart the mission at this point since I have got to this point before

I've taken it from orbit to land and back to orbit with loads of dV to spare. It's easy. 

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14 hours ago, Foxster said:

I've taken it from orbit to land and back to orbit with loads of dV to spare. It's easy. 

Oh well I guess I'm going to restart the mission anyway. 

the-new-lander-design-1.png

new-lander-design-2.png

This should make the mission easier. I also want to ask another question Why does my lander not spin out of control in air but does in space?

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Why does my lander not spin out of control in air but does in space?

Because you've turned off SAS? Because you've disabled the reaction wheel in the command pod? Because you have the fuel tanks at different priorities so they end up with different amounts of fuel and the CoM is offcenter? Because you only have a ladder on one side, so the CoM is offcenter? Because you somehow mounted your engine offcenter?

 

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1 hour ago, bewing said:

Because you've turned off SAS? Because you've disabled the reaction wheel in the command pod? Because you have the fuel tanks at different priorities so they end up with different amounts of fuel and the CoM is offcenter? Because you only have a ladder on one side, so the CoM is offcenter? Because you somehow mounted your engine offcenter?

 

1 No, 2 No, 3 maybe but this would have happened in the atmosphere, 4 No, 5 I evened out the CoM with the ladder design, 6 IDK how that can be?

12 minutes ago, Starwaster said:

Or maybe because it's drag stabilized?

I will have to test this!

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Can you elaborate on when and how it's happening?  It is just when you apply engine thrust, or all the time, or randomly?  Does it go slowly off target or does it start flipping like crazy?  

27 minutes ago, The Doodling Astronaut said:

6 IDK how that can be?

Hold the alt button when adding the engine; this will force it to attach to the node of the part above, which means it will be centered.  The Dart can be attached directly to any surface, unlike most engines, so it would be easy to place off-center by accident.

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36 minutes ago, Aegolius13 said:

Can you elaborate on when and how it's happening?  It is just when you apply engine thrust, or all the time, or randomly?  Does it go slowly off target or does it start flipping like crazy?  

Hold the alt button when adding the engine; this will force it to attach to the node of the part above, which means it will be centered.  The Dart can be attached directly to any surface, unlike most engines, so it would be easy to place off-center by accident.

I did check to make sure that it wasn't offset correctly. But I did found out about the cheats bar so now I can launch from the surface of laythe to test it!

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14 hours ago, The Doodling Astronaut said:

I did check to make sure that it wasn't offset correctly. But I did found out about the cheats bar so now I can launch from the surface of laythe to test it!

Get RCS Balancer. It has a mode for standard engines and it will tell you if the thing will torque or not under engine thrust. 

If you don't have it it is a MUST

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