Minmus Lander Design Problems

[NicholaiRen]

Hello guys,

 

I've designed this to land on Minmus. It has a nuclear engine on the bottom, 6 venor thrust engines, some RCS Blocks, and the top disengages(command pod, crew cabin,science junior) for reentry. It has a heat shield.

Now I have a few questions.

 

1. Is there a way to make this picture smaller? 

2. Is this enough to take off from minmus and fly back to kerbin?

3. Do the vector engines fire at different levels so that the ship will go up when I press H? Or will it simply go nose up since the center of mass is towards the back?

4. Can the crew cabin store surface samples? The idea behind this is to get as many surface samples from different biomes, and then return.

 

Just curious. And any tips?

 

 

[dave1904]

 I cant see the screenshot so I cant anwser 1 and 3

2. A nuclear engine seems like overkill to me but this is ksp  Just try it and if it fails try again. That is what rockets are about  Always keep your designs as simple as possible and for minmus a tiny lander can get to loads of biomes with normal chemical rockets

You can store as many surface samples as you like in crewed parts as far as I know.

[AeroGav]

The biggest problem with a nuclear lander is that the tallness can make it topple over.  Actually that is a problem with any lander.   I did build one and test it on Mun,  that was quite stable.

But,  as you can see the other problem is ladders.     They don't work.    Fortunately you can use your jet pack to fly back to capsule.

If you are patient, the lightest biome hopper is a rocket rover.      Use airplane wings to give it nice wide wheels and long wheelbase,  and airplane landing gear parts for the wheels (tougher than rover wheels).   There is no friction,  you can visit every biome with a few hundred delta V.    

Edited September 15, 2017 by AeroGav

[Cpt Kerbalkrunch]

I'm biased here because I despise the Nerv and never use it, so I definitely agree with @dave1904. That being said, I recognize it's usefulness and respect it's capabilities. However, that mostly applies to long-distance, interplanetary travel; to take advantage of it's high isp. With a lander, you instead expose all of its weaknesses. It's big, heavy, weak, expensive, and doesn't gimbal. Note that a Terrier has the same thrust but 1/6 the mass and 1/25 the cost. It's much shorter and has a gimbal as well; making it much easier to control. The Terrier is an ideal engine for landers and return stages. Though I can't see your screenshot (try using postimage or imgur; the you can post your pic directly into the thread so everyone can see it), I suspect the Vernors are unnecessary (unless you just like them). I realize your ship is already built, so I'm not advising a complete rebuild, just giving some suggestions for future consideration.

[NicholaiRen]

15 minutes ago, Cpt Kerbalkrunch said:

I'm biased here because I despise the Nerv and never use it, so I definitely agree with @dave1904. That being said, I recognize it's usefulness and respect it's capabilities. However, that mostly applies to long-distance, interplanetary travel; to take advantage of it's high isp. With a lander, you instead expose all of its weaknesses. It's big, heavy, weak, expensive, and doesn't gimbal. Note that a Terrier has the same thrust but 1/6 the mass and 1/25 the cost. It's much shorter and has a gimbal as well; making it much easier to control. The Terrier is an ideal engine for landers and return stages. Though I can't see your screenshot (try using postimage or imgur; the you can post your pic directly into the thread so everyone can see it), I suspect the Vernors are unnecessary (unless you just like them). I realize your ship is already built, so I'm not advising a complete rebuild, just giving some suggestions for future consideration.

It's a sideways lander. 

As in, it's not a single tall ship with lander legs at the bottom, it lays on it's side like a log, with lander legs at the top and bottom.

But I'll definitely take that into account next time. Mean while, the RCS hates me because it's set for a vertical vehicle, not a horizontal one.

 

It has however, landed and survived in perfect condition, with tons of fuel left.

 

Also, the nuclear engine is so that I could get twice as much fuel on for the same weight as a terrier engine.

I've found that in space and no atmostphere planets with low gravity, a lot of fuel and a little thrust is better then little fuel but high thrust. It's a lot of efficiency. And it's working amazing at the moment.

I've used the terrier engine, but they use up fuel so quickly and in my opinion, they're better for vertical landers.

 

 

 

The idea here is to design a lander quite capable of just about anything on moons. 

Edited September 15, 2017 by NicholaiRen

[Geonovast]

3 minutes ago, NicholaiRen said:

But I'll definitely take that into account next time. Mean while, the RCS hates me because it's set for a vertical vehicle, not a horizontal one.

RCS is based off of your "Control From Here" point.  Usually if I need to control a vehicle from an obscure spot, I'll slap a Jr. Docking port in that spot so I have something to click on and select "Control From Here"

So you could slap a docking port or probe core on the side, which would be the "top" when it's landing, and you should get correct control over your RCS.

 

[NicholaiRen]

17 minutes ago, Geonovast said:

RCS is based off of your "Control From Here" point.  Usually if I need to control a vehicle from an obscure spot, I'll slap a Jr. Docking port in that spot so I have something to click on and select "Control From Here"

So you could slap a docking port or probe core on the side, which would be the "top" when it's landing, and you should get correct control over your RCS.

 

That'll be what I do for the lander 2.0.

Also, the vector engines are pointed in the wrong direction.

 

 

It got back to Kerbin, and safely landed with all crew and science modules.

So of 5 tests, it works.

It can be sent to orbit.

It can land on minmus.

It can take off of minmus.

It can return back to Kerbin with a generous amount of fuel left(25%), from the opposite of ideal timing(took off at the worst time on purpose)

It can operate very well in space with RCS.

 

 

Based on this, it's designed to land on a moon, fly around for a while, and then return back to orbit and dock with a interplanetary tug.

Which I've yet to design. 
It can refuel with the tug.

So the port was going to be added anyways, I just didn't realize it'd be so much more useful as a control point.

Edited September 15, 2017 by NicholaiRen
Update

[Geonovast]

Your picture still isn't showing and I'm likely imagining your craft wrong.  Can you try linking the picture again so it shows, or at least a link to it?

[AeroGav]

@Cpt Kerbalkrunch  I think he wants to biome hop mulitple times.   The delta V requirements quickly get huge even on a small moon, so it sort of makes sense.  Given the cost, you want to re-use that ship - leave it in orbit and refuel,  of at least land it on kerbin intact and close to KSC.

@NicholaiRen  I have updated my previous post of a video i took of one of my nuke landers, being tested on the Mun.        It worked ok, the ladders not so much.

[NicholaiRen]

39 minutes ago, Geonovast said:

Your picture still isn't showing and I'm likely imagining your craft wrong.  Can you try linking the picture again so it shows, or at least a link to it?

https://lh3.googleusercontent.com/-GxJpgjIySBA/Wbvf86BJ6VI/AAAAAAAAA6M/3LJHF4QM2oYeraf_PfEf0wrmttczPiyhwCL0BGAYYCw/h720/screenshot8.png

 

 

I love those big legs.

I  touched down at 30m/s(about 20m/s sideways) and not one of them even blew up. 

Also, this is the second version. So there's a few changes.

Edited September 15, 2017 by NicholaiRen

[NicholaiRen]

Second version ran out of fuel for the vector thrusters.

Other then that, worked great.

[Cpt Kerbalkrunch]

@NicholaiRen, now that I saw your screenshot, I get what you're doing. I can imagine it sideways. The fuel lines I use to connect modules on bases look somewhat similar, but I had never thought to land a ship that way. In definite agreement with @AeroGav; bio hopping anywhere but Gilly gets expensive quick. It's those situations where my hatred of the Nerv (and God forbid, the Dawn) comes around to bite me. For biome hopping, I generally use a mothership with the smallest lander I can get away with. My go-to method would be Mk1 Lander Can and however many Oscar B's and Sparks I need. Do a couple times and refuel at the mothership to start over. For a larger world, I usually just slap a couple drills on it and make the whole thing self-sufficient. Always interesting to see other methods, though.

[AeroGav]

To be honest Biome hopping is something i avoid anyway, it's a way to grind enough science to fill the tech tree from Mun and Minmus.    KSP is an exploration game so these days i don't go out my way to do it,  if i can easily hit 2 biomes in 1 mission i will, but otherwise i go home, bank the science and plan another journey further afield.

 

[Spricigo]

My thoughts:

-the arrangement [command pod, crew cabin,  material bay] probably have the tendency to reentry nose first after you ditch the rest of the vessel. The alternative [crew cabin, command pod], with the material bay moved to another  stage, will make the cabin's hatch available and  ensure a  stable bottom first reentry.

-vernor, RCS..., no reason to use both.  They realise the same function using different fuel. Chose one kind  and get rid of the other 

-...reaction wheels and SAS. The reason you are running out of RCS(/vernor) fuel is probably that you are wasting it with rotation movement and SAS overcorrection. Go yo settings and enable advance tweakables. When building you next ship right click on the  RCS/vernor thruster [show activation toggles] and turn of pitch, yaw and roll. Rotation will be deal with your reaction wheels and you can keep the fuel for when precise translations is necessary.

-landings legs/gears. You may use landings gears to make it also capable of taxing around if necessary.  Also on the  plus side you can land with a considerable horizontal velocity and use brakes to stop (saves fuel).

-engines. You are not taking much advantage of the Nerv high isp but carrying all its shortcomings. The 6t can be better used with chemical engines (my suggestion is a pair of Sparks or Twitchs, if that is not availavle a terrier) and extra fuel. The additional tanks being radially attached will allow the craft to be shorter and more maneuverable.  A case for the nervs can be made the reusability/recoverability of the vessel ia increased but as it stands now the fuel burned by chemical rockets is way cheaper than a nuclear engine left behind. You will expend fuel twice as quickly than with a nerv but that is not a problem if you have 3 times more fuel for the same mass.

Well, if you can provide a image of your tech tree and a description of the requirements,  I may try to design a chemical alternative tailored for your. Meanwhile I offer this one , is optimized for a different situations, carry only one kerbal and not designed to reentry, but with small adjustment can be a pretty effective minmus biome hopper.

 

[Palaceviking]

I think a lot of people are missing your point with the nerv, I quite like their isp too, a fuel tanker and return pod built in a modular fashion(Jr docking ports?, with your lander as the drive section and return pod/science container on the opposite end?) are needed though to justify the weight and cost of the thing though. 

 

I would start practicing your launch to rendezvous

[Spricigo]

38 minutes ago, Palaceviking said:

I think a lot of people are missing your point with the nerv, I quite like their isp too, a fuel tanker and return pod built in a modular fashion

I have my doubts that's the idea. But assuming it is, more reason to not use it  in the presented configuration.

 Small chemical rockets cam offer better performance for less (easily) for that task.  To justify the nuclear option either larger deltaV or full part recovery is required (and maybe full recovery turn out to be not enough).  In the current conditions mass fraction make more difference than Isp. 

[Palaceviking]

I wan kinda thinking long term reusability, as soon as I unlock the nerv I start using it with docking ports,  I still have my first tugs from year 1 knocking around the system many years later just needing a fuel delivery to become awesomely useful again.

"For me the career game is all about infrastructure and that is where the nerv really shines."  -NAS 

[Spricigo]

11 minutes ago, Palaceviking said:

I wan kinda thinking long term reusability

Ok, but chemical rockets can be also made reusable. And they will still be more efficient for certain tasks while not for others.

22 minutes ago, Palaceviking said:

"For me the career game is all about infrastructure and that is where the nerv really shines."  -NAS 

Merely, it lose one disadvantage: price.  It is still heavy and weak. Those are in a large majority of cases the important limiting factors for nuclear propulsion.  (Specially considering how easy is to make money in KSP) .

 

[Palaceviking]

(not giving up ;) ),  after using it as a minmus lander though it can be fitted with appropriate fuel tanker and used as an interplanetary tug with the option of lo-grav landings when you get there?? 

 

[Spricigo]

16 minutes ago, Palaceviking said:

(not giving up ;) ),  after using it as a minmus lander though it can be fitted with appropriate fuel tanker and used as an interplanetary tug with the option of lo-grav landings when you get there?? 

In that case you can also wait for this later moment not only to fit more appropriate fuel tank but also change the engine if that is the more effective. (There is a big chance that a chemical lander with a nuclear tug will still be better)

Also, why not build dedicated landers AND dedicated tugs instead? That way you dont need to bring the lander all the way from ike to send it to gily. And each vessel can be optimized for what it do and stay where it is most useful. 

 

[Palaceviking]

50 minutes ago, Spricigo said:

In that case you can also wait for this later moment not only to fit more appropriate fuel tank but also change the engine if that is the more effective. (There is a big chance that a chemical lander with a nuclear tug will still be better)

Also, why not build dedicated landers AND dedicated tugs instead? That way you dont need to bring the lander all the way from ike to send it to gily. And each vessel can be optimized for what it do and stay where it is most useful. 

 

More vessels = more cost?

I'm really into isru so it suits my playstyle to reuse everything,  each to their own of course... 

[Spricigo]

6 hours ago, Palaceviking said:

More vessels = more cost?

I'm really into isru so it suits my playstyle to reuse everything,  each to their own of course... 

 Pretty often: More vessels, less cost. It's a matter of noticing those occasions and taking advantage.

No amount of ISRU and reusability will solve the issue of a suboptimal design, in fact as you use that design more and more it become a bigger issue. 

Of course we don't need to agree about what make a particular design 'optimized' . 

 

[Palaceviking]

Isru = infinite fuel,  efficient and optimal design become irrelevant if they do the job 

[Spricigo]

48 minutes ago, Palaceviking said:

Isru = infinite fuel,  efficient and optimal design become irrelevant if they do the job 

Efficiency is not only about cost, there's time, reliability, usability...

If you have two crafts that are otherwise equal, certainly you will prefer to use the  more [insert quality here]. 

Don't take me wrong. The nerv is great, just not always.