Feedback on wide Mun lander

[martincmartin]

I want to land on the Mun and do a full science survey (of instruments I've unlocked).  Last time I tried, my lander kept falling over (yay quicksave!).  So I need a wider base.  Here are two designs.  Thoughts?

[Signo]

To avoid flipping I prefer short&wide landers.

[Green Baron]

Near perfect the first design. The second design could be tight on dV for a beginner.

My suggestions: 3 legs are enough and put them as far down as possible, strip the ladders (fly jetpack on the mun), strip the rcs-ports and the 2.5 to 1.25-adapter, that's just overweight. For easier reenrty: use a 2.5m heatshield and adjust the ablator to 160 or 240, that makes it easier and avoids flips in the atmosphere (pe on reentry around 25km). Then you can forget about the casing as well and glue the parts inside on the outside of the experiment container. Don't forget a battery and solar panels. And i'd use 2 of the larger lateral parachutes (1 would be enough but balance ...) instead of the tiny one. In that case you could take 2 versions of the experiments.

 

 

[lrd.Helmet]

I suspect you don't have fairings yet? 

The first design is pretty good, but you should remove the rcs. And aren't you able to move the experiment data to the capsule? (by EVA that is). Because I think your capsule wont be stable on reentry.
Oh and remove the ladders too.

If you can move the data around with an EVA the craft should be like this (from top to bottom): parachute>capsule>heatshield>decoupler>science and other stuff> adapter > fuel (with legs attached)> engine.

PS: Make sure the legs give enough ground clearance for the engine bell.

Edit: oh and power! batteries or solar panels!

Edited May 6, 2016 by lrd.Helmet

[SnakyLeVrai]

Yeah, on 1st design, it's a bit tall indeed. As stated above, batteries and solar panels will make your life better

2nd design will be more stable on the ground, that's true  If it's short on dV for beginner level, then add more fuel  TWR is aplenty on this design, so you just need to add more fuel.

Also, be careful for reentry, as you have a very long reentry vessel due to Science Jr and Mk1 Cargo Bay. Do this:

1. Make sure the command pod is the root part (it helps for step 3)
2. Display the Center of Mass (CoM) in the VAB
3. Detach the bottom part of the lander (click on the decoupler to detach the whole base and put it away for a moment)
4. Look at the position of the CoM : it needs to be located at least in the lower 1/3rd of the reentry vessel. If it's higher, there's a risk of flipping & burning during reentry. --> Tweak the monopropellant, parts placement, ablator and stuff to make the CoM as low as possible.
5. When it's all adjusted correctly, you can put the base back in place.

[katateochi]

I'd say the first one is way overpowered, easily twice as much dV as required.  I reckon on having 1200-1400dV for de-orbiting, landing and returning to orbit.
I also imagine that it's going to be quite sluggish to maneuver (unless you've got more SAS hidden in the service bay), which might make things harder in the final stages of landing.  Maybe that's why you've got RCS on it, to help with that? But unless you're planning to dock you generally don't need RCS (although....a little RCS thrust has saved some missions that fell short of enough dV to make it back home, beats getting out and pushing!). 

I prefer your 2nd design. It's more dV efficiency and maneuverable; should be able to land, return to orbit and transfer back to Kerbin and will be able to make quick adjustments as you're coming into land. But it is kinda tall and narrow and I'm not a fan of using those cubic struts like that (mostly from aesthetic point of view).

My standard design for a small 1 man Mun sci lander uses 1 FL-T200 and 2 FL-T100s tanks (rather than a single LF-T400) with the two FL-T100's radially mounted sideways on the T200.  This is an old pic of that sort of design, but still pretty close to what I use these days. (It does need fuel lines to connect the T100s to the T200.)

I really don't like how the legs are placed in this pic, I was experimenting with having 3 legs, so the front two ended up rather clipped.  What I generally do is attach just one T100 tank, then attach the legs to it so symmetry works around it, then remove and re-attach the tank+legs so you end up with 4 symmetrically placed legs (I've not seen how 1.1.x behaves with symmetrically attaching parts which have symmetrically attached parts, but hopefully that still works).
That gives you a shorter lander while also letting you put the legs wider apart.

[Warzouz]

If you've difficulties to land on the Mun, I suggest removing the adapter and the service bay. Don't be too upset with streamlining. If you have a hard time reaching space, go a bit straight up. Further more, set your decoupler under the pod and recover your data before decouple into space. No need to recover those parts.

You can also use a Terrier instead of a Poodle and use a smaller fuel tank. Set a stage from LKO to near landing (around 1500m/s)

 

Edited May 6, 2016 by Warzouz

[Barefoot Friar]

Introducing the Allison Wonderland Design Bureau's Lander Pack!

Link to Google Drive depository, including the README file.

I've designed a few landers, and you're welcome to take them and make whatever changes you want.

I don't know where you are on the science tree, so you may have to remove several parts before it will let you launch it.  Also, none of these are rated for atmospheric reentry.

Hope this helps.

Edited May 6, 2016 by Barefoot Friar
Formatting

[Scotius]

There are couple of my older designs  

Maybe something will be useful to you.

Edited May 6, 2016 by Scotius

[RizzoTheRat]

My early game Mun/Minmus landers look very much like Signo's in the second post, but with nose cones on the side tanks.  I usually have a booster/transfer stage that gets me to the mun, the radial tanks have enough to finish any braking and orbit adjustments and then land.  They then get jettisoned a couple of hundred meters up on takeoff (high enough not to leave debris) and the center tank has enough fuel to get back to Kerbin.

 

Later game I go for a much wider landing gear so I can drop in to some of the rougher biomes without worrying about tipping over

Edited May 6, 2016 by RizzoTheRat

[N_Danger]

I built this last week in a new science game. You could strip off the can and use a capsule. I did do it Apollo style with a CM in orbit but I think it could be tweaked for a direct return. I also tend to not use the materials bay on a lander to keep the center of mass as low as possible. That is just a personal choice and it does mean less science gained.

[herbal space program]

Those both look like they could do the job, but there's lots of stuff you could do to make them less flippy. It's  important to position your legs as high as possible relative to your center of mass, and your center of mass is currently way above them. It's also good to minimize your overall moment of inertia by concentrating the heavy parts in the center. You can accomplish the first thing by mounting your landing legs higher on your bottom tanks. Your exhaust nozzle should clear the ground after you've landed by just enough that you don't bottom out. Your legs are way lower than they need to be for that. Actually, you should be using the bigger struts on the bigger lander too. The other thing you can do, although it looks kind of silly, would be to mount your light materials bay on top of your command pod using a couple of struts and radial parachutes. That would concentrate mass in the middle and make you less tippy in general. I'll bet if you do just those two things you'll find you have a lot less difficulty landing upright....And I agree with other that that Poodle is waay OP for a basic Mun lander. You could lift a 22-ton lander off of Tylo with that!

4 hours ago, Green Baron said:

My suggestions: 3 legs are enough and put them as far down as possible...

Nonono, they need to be as *high* as possible. The further above the point of attachment the COM of the lander is, the more it will want to flip if it hits the ground slanted. Also, four legs requires significantly more rotational energy to flip on its side than three, so that will also make the lander perform worse and not better.

Edited May 6, 2016 by herbal space program

[teag2]

My Mun Lander designs are pretty simple. Several drop-tanks on the sides with landing legs connecting to a single tank with a Terrier beneath it. That stage also has all the SCIENCE! attached to it. Above that is the command pod with a heatshield, several batteries, and a parachute. Be sure to add solar panels, as you don't want to lose your SAS mid-landing.

Oh, and don't bother with ladders, as a Kerbal can easily lift off on the Mun with their jetpack.

[ToukieToucan]

1 hour ago, RizzoTheRat said:

My early game Mun/Minmus landers look very much like Signo's in the second post, but with nose cones on the side tanks.  I usually have a booster/transfer stage that gets me to the mun, the radial tanks have enough to finish any braking and orbit adjustments and then land.  They then get jettisoned a couple of hundred meters up on takeoff (high enough not to leave debris) and the center tank has enough fuel to get back to Kerbin.

 

Later game I go for a much wider landing gear so I can drop in to some of the rougher biomes without worrying about tipping over

That's a clever use of wings, what did your launch vehicle look like?

[Warzouz]

Also, a trick I discovered in 1.0.4+ (but I don't know if it's still working in 1.1+)

When you land on a slope, deactivate the suspension of the lower landing strut, it seem to reduce the risk of you COM passing over your lower leg due to bouncing. 

I successfully landed several time a heavy lander (40T) on a nearly 30° slope with only 4 heavy struts in 1.0.4.

[Alshain]

Well, you don't need RCS to land on the Mun.  Also, if you have a lander can it would be significantly less mass.  Less mass = less required fuel.  Also, the adapter you are using is pretty heavy, if you can enclose the whole thing in a fairing it isn't necessary.

[herbal space program]

8 minutes ago, Alshain said:

Well, you don't need RCS to land on the Mun.  Also, if you have a lander can it would be significantly less mass.  Less mass = less required fuel.  Also, the adapter you are using is pretty heavy, if you can enclose the whole thing in a fairing it isn't necessary.

But OP's problem was tipping over when landing, not fuel consumption. Eliminating RCS will make that worse and not better, both by requiring better flying skills to manage the approach and by providing less rotational stabilization after contact.

Edited May 6, 2016 by herbal space program

[Warzouz]

1 hour ago, Alshain said:

Well, you don't need RCS to land on the Mun.  Also, if you have a lander can it would be significantly less mass.  Less mass = less required fuel.  Also, the adapter you are using is pretty heavy, if you can enclose the whole thing in a fairing it isn't necessary.

 

Yes and even docking need very little RCS monoprop. 1 unit per ton is enough. So you could dock a 10T lander with only the fuel inside a MK1 landing can. Personnaly I never use RCS tanks except on refueling stations. (My heavy lander is an exception, but it weights 60T when docking. Those round RCs tanks are only 25% full.

Edited May 6, 2016 by Warzouz

[Foxster]

I think the above shows that the general principle is to make it wide and squat. This often means a few lower power engines bolted on the sides, rather than one big engine on the bottom. 

[Alshain]

 

8 minutes ago, herbal space program said:

But OP's problem was tipping over when landing, not fuel consumption. Eliminating RCS will make that worse and not better, both by requiring better flying skills to manage the approach and by providing less rotational stabilization after contact.

RCS doesn't solve the tipping problem, nor is it really usefull on approach.  By keeping the monoprop, he has more mass at the top of the ship which works against him and is just that much more likely to tip.  A tall, top heavy craft will tip.  A wide bottom heavy craft is less likely to do so.

[ToukieToucan]

What I mostly do is look for a relativity flat area and touchdown slower than 1 m/s, it stops you from bouncing.

[herbal space program]

21 minutes ago, Alshain said:

 

RCS doesn't solve the tipping problem, nor is it really usefull on approach.  By keeping the monoprop, he has more mass at the top of the ship which works against him and is just that much more likely to tip.  A tall, top heavy craft will tip.  A wide bottom heavy craft is less likely to do so.

I don't know how you can say that having RCS helps with neither approach nor tipping over. Maybe it doesn't help you with your awesome flying skilz , but you know us regular folks do  like to be able to line up all the indicators with RCS translation rather than by pitching this way and that while plummeting towards the surface.  And if one doesn't stick the landing as I'm sure you always do, every bit of rotational damping you can get from having RCS/SAS engaged also helps. As you might have noticed looking upthread, I already suggested to OP that the capsule should be lower down, below the two bays, and the legs higher. Those changes will decrease the MOI far, far more than getting rid of a measly .05t of monoprop.

Edited May 6, 2016 by herbal space program

[Alshain]

6 minutes ago, herbal space program said:

I don't know how you can say that having RCS helps with neither approach nor tipping over. Maybe it doesn't help you with your awesome flying skilz , but you know us regular folks do  like to be able to line up all the indicators with RCS translation rather than by pitching this way and that while plummeting towards the surface.  And if one doesn't stick the landing as I'm sure you always do, every bit of rotational damping you can get from having RCS/SAS engaged also helps. As you might have noticed looking upthread, I already suggested to OP that the capsule should be lower down, below the two bays, and the legs higher. Those changes will decrease the MOI far, far more than getting rid of a measly .05t of monoprop.

It doesn't take RCS to line up the indicators.  You keep making comments like "your awesome flying skilz", my skills aren't particularly great, I just know how to land.  Using RCS as a crutch does nothing but teach you how to use RCS as a crutch.   If you teach yourself to land without it then you learn to land.  If you want to use RCS to land, that is fine.  The great thing about this game is you can play it as you want, but I'm not going to teach a new player to do that. 

As for rotational dampening after touchdown, that is more likely to land a new player in hot water.  A new player is more likely to overshoot using RCS, or just lose track of center and blast the RCS in the wrong direction.  So on top of being unnecessary now you have an increased chance of disaster.

I agree moving the pod down lower will help, but also taking unnecessary equipment just adds to the problem.  I prefer to teach a new player to do it right the first time than to rely on a crutch and then have to re-learn the whole thing all over again.

[herbal space program]

13 minutes ago, Alshain said:

It doesn't take RCS to line up the indicators.  You keep making comments like "your awesome flying skilz", my skills aren't particularly great, I just know how to land.  Using RCS as a crutch does nothing but teach you how to use RCS as a crutch.   If you teach yourself to land without it then you learn to land.  If you want to use RCS to land, that is fine.  The great thing about this game is you can play it as you want, but I'm not going to teach a new player to do that. 

As for rotational dampening after touchdown, that is more likely to land a new player in hot water.  A new player is more likely to overshoot using RCS, or just lose track of center and blast the RCS in the wrong direction.  So on top of being unnecessary now you have an increased chance of disaster.

I agree moving the pod down lower will help, but also taking unnecessary equipment just adds to the problem.  I prefer to teach a new player to do it right the first time than to rely on a crutch and then have to re-learn the whole thing all over again.

Boy do you and I have different pedagogical styles. In case you have forgotten, for a brand new player landing on the Mun without the benefit of RCS translation is really, really hard. I sure haven't forgotten. I could never have done it in the first few months of playing, but of course like you I can do it pretty easily now. It is absolutely false that having RCS as a "crutch" early on made me unable to learn how to do it "right". What it did was make it fun instead of a mind-numbingly frustrating and tedious challenge. As to getting in hot water with RCS, I  wasn't suggesting trying to correct manually. Of course that will do more harm than good. But it will of course also add significant power to the SAS system, which could easily make the difference between ending up upright vs. sideways. Anyway, I seldom find that I make somebody feel like they've actually been helped by telling them they're doing it all wrong from the get-go. YMMV.

[Alshain]

7 minutes ago, herbal space program said:

Boy do you and I have different pedagogical styles. In case you have forgotten, for a brand new player landing on the Mun without the benefit of RCS translation is really, really hard. I sure haven't forgotten. I could never have done it in the first few months of playing, but of course like you I can do it pretty easily now. It is absolutely false that having RCS as a "crutch" early on made me unable to learn how to do it "right". What it did was make it fun instead of a mind-numbingly frustrating and tedious challenge. As to getting in hot water with RCS, I  wasn't suggesting trying to correct manually. Of course that will do more harm than good. But it will of course also add significant power to the SAS system, which could easily make the difference between ending up upright vs. sideways. Anyway, I seldom find that I make somebody feel like they've actually been helped by telling them they're doing it all wrong from the get-go. YMMV.

I haven't forgotten, I never used RCS to land on the Mun, ever.  It's not that hard to do it without it.  All I can think is maybe you have a different approach to actually landing because none of the ways I have ever landed needed RCS.   Even back when I was doing the whole inefficient, "kill your orbit and come straight down method"  I still didn't use RCS  (which I will also not teach btw, it's a terrible way to land and again it just teaches you to do it badly).  Practice makes perfect of course, I didn't land on my first try, but it was probably only the 4th or 5th attempt that I got it to stick.

Your last sentence is just ridiculous outright.  I have no idea what you are referencing there.  I told him how to improve his craft, that is what he asked for.  In fact if you are going to try and make thinly veiled accusations that don't even make sense I'm done discussing it with you.