NERV Duna lander ideas

[Giygus]

I just got enough Science to unlock the nuclear engine, and I want to build a Duna lander with one, to make my first landing on the planet.  The thing is the damn engine is so long, my imagination is failing me on an elegant way to build, and put landing struts and a ladder on it.

After spending an hour getting frustrated, it occurred to me that approximately everyone reading this has already built one, or something like it.  Any tips or pictures you have would be awesome!

A few points: 

• The mission is full science (I don't have upper level experiments unlocked yet).
• I am planning on not activating the lander (NERV) stage until getting into Duna orbit.  However, I was planning on trying to biome hop once or twice.  The lander I was working on had 6000+ Dv, and had a 1.2 thrust on Duna, with about 17 ton weight.
• I was planning on only bringing a scientist to reset and collect experiments.  However, that means the experiments need to be within his reach and a probe core is needed.
• I have all engines unlocked, as well as the largest fairing.  So long as it isn't crazy wide, un-areodynamic stuff should be fine.
• I was planning on having the entire lander reenter Kerbin, using the parachutes, but I guess I am not married to that.
• The only addon I have is mechjeb.  So un-stock parts would mess me up

OK, so here is what I have so far:

 

UPDATE:

So after reading everyones posts, here is what I am going with.  Decided that the NERV engine was not the best way to go, everyone was making that a pretty strong point.  I will be using Nerv for transfer stage, which will be brought into orbit separately and attached with the docking ports.  Will send an unmanned refuel pod first, to maximize hopping potential.

Again, thanks for all the help!

 

Edited May 6, 2016 by Giygus
Pictures messed up

[James Kerman]

 

You can also use the offset tool to tuck the nerva into its fuel tank.

Edited May 4, 2016 by James Kerman

[Superfluous J]

For that small a lander, I'd just use a small chemical rocket. It's been a while since I've been there but I think the Terrier works fine in Duna's thin atmosphere.

You're probably spending a lot of your efficently-burning fuel to lift all that engine, whereas you'd burn a lot less fuel (albeit a bit less efficiently) to lift a much smaller craft.

[Quasar]

I'd use 2 NERV's and build it upside down. Put the command module on or near the bottom, science, control systems and central tank above that, then finally attach a pair of tanks using 2x symmetry put the NERV's under those. You'll want extra fuel if you do that though: NERV's are heavy.

 

You can tuck them in right alongside your command module, which is great for irradiating Kerbals. Uh, I mean... "I do not condone irradiating Kerbals. That would be bad."

[FancyMouse]

My suggestions:

1. You probably want to start using nuke as soon as you get orbit. Your lander can be minimal and leave fuel tanks in Duna's orbit - acting as a temporary refueling station. In other words, the lander only needs ~1.5km/s for launching from Duna surface to orbit and everything else is left on Duna orbit.

2. You can save the LFO tank height by connecting directly from LF tank to engine with fuel lines. Science bay provides the surface attaching point for fuel tanks.

3. You can save the reaction wheel height on the main stack by changing to a smaller one and fit it into the service bay. I even wonder if the reaction wheel from pod itself is enough.

4. Ladder is not a must. EVA RCS has just enough thrust to lift off a kerbal (unless you have KAS/KIS that kerbal could be heavier)

[Plusck]

The only lander with a NERV that I ever built was unashamedly ripped off (or is that ashamedly, maybe) from a video by S__t M_____.

Basically the engine directly under a MK1 lander can, with Mk1 LF tanks with 4x radial symmetry attached to the lander can then another set under them, and landing legs on the bottom. And don't forget the fuel lines.

The only trouble is that it really is a heavy and unwieldy beast. I wouldn't do it again because Terriers (or for more thrust, aerospikes) are just so much more comfortable and fun to fly.

Edited May 4, 2016 by Plusck

[bewing]

As far as "landing legs" go, my favorite thing to do with NERVs is to use the Type B swept wings. Fairly low drag during launch & weigh less than 2 girders. I use the offset tool to move the wings down 6 "clicks" until they line up with the engine bell (or a little below). But this rules out the use of fairings for the lander. I just go straight up through the atmosphere as fast as I reasonably can. After you get past the first 35km the fairings are useless anyway.

 

 

 

Edited May 4, 2016 by bewing

[Foxster]

Just a thought...Are you visiting Duna's surface at this point for the science? If so then I'd not bother. I'd visit the Sun's high orbit, Duna low and high orbit, plus Ike low and high orbit and surface in one mission first. That will likely finish the tech tree or at least give you the rest of the science experiments before tackling Duna itself. 

If you are set on doing Duna then I suggest nukes aren't necessarily the best engine. They have a sweetspot for more massive ships, usually space tugs. As was suggested above, you may find Terriers or other chemical engines give more dV.   

I do agree with clipping the nuke engine into a tank...

 

Edited May 4, 2016 by Foxster

[Norcalplanner]

I'd also suggest playing around with Meithan's engine app.  It's a good tool for comparing options for a particular mission profile.

http://meithan.net/KSP/engines/

 

[mk1980]

5 hours ago, Giygus said:

 

• I am planning on not activating the lander (NERV) stage until getting into Duna orbit.  However, I was planning on trying to biome hop once or twice.  The lander I was working on had 6000+ Dv, and had a 1.2 thrust on Duna, with about 17 ton weight.

 

if you're going to haul such a heavy engine to duna, i think it's a bad idea to only fire it when you are there. nukes are really good for transfers, so if you're going to bring one, it would be a good idea to use it for the one thing it does really well.

with your mission plan, you'd need an additional transfer stage that gets you from kerbin orbit to duna orbit (which seems to be missing in the image?)

slap on some drop tanks for the nuke that act as the "transfer stage" that gets you from kerbin to duna. could also be used for the final part of kerbin orbit circularization if needed.

 

EDIT: also - there's a bit of a logistics problem with the 1 man command pod. you can either bring a scientist to reset the experiments or an engineer to repack the chutes, but not both. without an engineer, the chutes are basically one time use, so you'd have to do powered landings all the time. might be cheaper to add another pod and also bring an engineer along to save a big chunk of deltaV every "hop".

Edited May 4, 2016 by mk1980

[RizzoTheRat]

Not tried it on Duna but this worked very well for a Minmus/Mun lander.  Rather than having 2 engines, I put 1 engine on the centreline, with a small fuel tank on top, and then built symmetrically from the fuel tank.  2 Mk1 cans means it can collect 2 sets of experiments from every landing, although the crew had to be returned in Mk1 pods to recover their data separately.  Pushing it's fuel dump an then leaving that in orbit it was able to land in every biome on Minmus, transfer to Mun, and then do a further 2 biomes on Mun before needing refueling.  It's main weakness is it probably can't aerobrake.  I did wonder about using a shielded docking port and heat shields on the roof for longer distance missions but that might prove too heavy.

[Nich]

Here are mine but they really are not the best option.  I really only did it because the nuke was the only engine used for the mission with a supply tank left in orbit.  I think I got something like 9000 ish dv out of that engine.

 

Edited May 4, 2016 by Nich

[Stoney3K]

7 hours ago, Plusck said:

The only lander with a NERV that I ever built was unashamedly ripped off (or is that ashamedly, maybe) from a video by S__t M_____.

Basically the engine directly under a MK1 lander can, with Mk1 LF tanks with 4x radial symmetry attached to the lander can then another set under them, and landing legs on the bottom. And don't forget the fuel lines.

The only trouble is that it really is a heavy and unwieldy beast. I wouldn't do it again because Terriers (or for more thrust, aerospikes) are just so much more comfortable and fun to fly.

These days I even use a foursome of 48-27 Sparks in place of Terriers. More thrust, less weight, flatter footprint and a higher Isp in atmosphere.

The only difference is a lower vacuum Isp, but that is offset by 20% less engine weight to haul around.

[Gojira1000]

I'll second the terriers for a Duna lander - leave the NERVs in orbit on your transfer stage.

[tg626]

Just an example, this made the landing. Then left the bottom behind on ascent.

This is how it got there, assembled in orbit and NERV powered (crazy long burns tho) 

Edited May 4, 2016 by tg626

[Giygus]

19 hours ago, 5thHorseman said:

For that small a lander, I'd just use a small chemical rocket. It's been a while since I've been there but I think the Terrier works fine in Duna's thin atmosphere.

You're probably spending a lot of your efficently-burning fuel to lift all that engine, whereas you'd burn a lot less fuel (albeit a bit less efficiently) to lift a much smaller craft.

This was my first start:

Spoiler

It is about 1 ton less weight, but has ~2K less Dv.  Thrust to weight is about the same.  When I decided I wanted to planet hop around some, to get a few biomes worth of studies done in one trip, I started thinking NERV.  Since the T vs W ratio is about the same, I think they will both perform the same in that regard.

19 hours ago, Quasar said:

I'd use 2 NERV's and build it upside down. Put the command module on or near the bottom, science, control systems and central tank above that, then finally attach a pair of tanks using 2x symmetry put the NERV's under those. You'll want extra fuel if you do that though: NERV's are heavy.

 

You can tuck them in right alongside your command module, which is great for irradiating Kerbals. Uh, I mean... "I do not condone irradiating Kerbals. That would be bad."

I was hoping to bring the entire lander in through Kerbin's atmosphere at the end of the mission.  Not sure how the pod would survive that unless I am really careful about areobreaking, which I usually hate doing in a "RL time vs. fun-in-video-game" thing.  Although I understand it is a very nifty maneuver.

15 hours ago, Foxster said:

Just a thought...Are you visiting Duna's surface at this point for the science? If so then I'd not bother. I'd visit the Sun's high orbit, Duna low and high orbit, plus Ike low and high orbit and surface in one mission first. That will likely finish the tech tree or at least give you the rest of the science experiments before tackling Duna itself. 

If you are set on doing Duna then I suggest nukes aren't necessarily the best engine. They have a sweetspot for more massive ships, usually space tugs. As was suggested above, you may find Terriers or other chemical engines give more dV.   

I do agree with clipping the nuke engine into a tank...

I am visiting for Science points/role play.  Visiting surface was next up in mission control storywise, and I was getting bored with Mun landings and didn't feel like building a station yet.  I cannot get more Dv out of a Terrier/Poodle, any hints?  The picture above was about my best attempt, and I was a lot of Dv off from the NERV.  I will make another point on this "sweetspot" below.

15 hours ago, mk1980 said:

if you're going to haul such a heavy engine to duna, i think it's a bad idea to only fire it when you are there...

...with your mission plan, you'd need an additional transfer stage that gets you from kerbin orbit to duna orbit (which seems to be missing in the image?)

slap on some drop tanks for the nuke that act as the "transfer stage" that gets you from kerbin to duna. could also be used for the final part of kerbin orbit circularization if needed.

 

EDIT: also - there's a bit of a logistics problem with the 1 man command pod. you can either bring a scientist to reset the experiments or an engineer to repack the chutes, but not both. without an engineer, the chutes are basically one time use, so you'd have to do powered landings all the time. might be cheaper to add another pod and also bring an engineer along to save a big chunk of deltaV every "hop".

The transfer stage is part of the lifter stage.  I get to 605KM above the surface with the Twinboars having about 1000Dv left (after dropping off the outer tanks/SRB), and let Mechjeb create a maneuver point using the "porkchop" method.  I fast forward a few years and get to Duna needing about 800DV, get into orbit with whats left, then drop the boars to land (at least that's the plan).

The logistics problem is not an issue because I was NOT planning on using parachutes to land on Duna, only on reentry onto Kerbin.  Dv Map says it takes ~1500 Dv to land from orbit, so lets say each "hop" is 1500, and I should get at least 2 hops before I go back to orbit/return burn to Kerbin, which will be "porkchoped" for efficiency.  I suspect it will take less then 1500 to hop though, so I am hoping for 3+, won't know till I get there!

18 hours ago, FancyMouse said:

My suggestions:

1. You probably want to start using nuke as soon as you get orbit. Your lander can be minimal and leave fuel tanks in Duna's orbit - acting as a temporary refueling station. In other words, the lander only needs ~1.5km/s for launching from Duna surface to orbit and everything else is left on Duna orbit.

2. You can save the LFO tank height by connecting directly from LF tank to engine with fuel lines. Science bay provides the surface attaching point for fuel tanks.

3. You can save the reaction wheel height on the main stack by changing to a smaller one and fit it into the service bay. I even wonder if the reaction wheel from pod itself is enough.

4. Ladder is not a must. EVA RCS has just enough thrust to lift off a kerbal (unless you have KAS/KIS that kerbal could be heavier)

1:  I do not feel qualified to do rendezvous all the time, and wanted to avoid them.  I did it a few times for practice, rescuing kerbals here and there, found it to be a time consuming PITA.  Never built a lander ship in 2 stages.  It is a viable option though.

2:  Didn't think Science bay could provide attaching point, good idea

3  Reentry into Kerbin seems dicey unless I have a strong reaction wheel to keep things all retrograde.  I never bothered to use Heat shields. 

4:  EVA RCS = PITA.  Was hoping to use ladders, but again, its a fair point.

16 hours ago, Plusck said:

The only lander with a NERV that I ever built was unashamedly ripped off (or is that ashamedly, maybe) from a video by S__t M_____.

Basically the engine directly under a MK1 lander can, with Mk1 LF tanks with 4x radial symmetry attached to the lander can then another set under them, and landing legs on the bottom. And don't forget the fuel lines.

The only trouble is that it really is a heavy and unwieldy beast. I wouldn't do it again because Terriers (or for more thrust, aerospikes) are just so much more comfortable and fun to fly.

Why are they "more comfortable and fun"?  Just because the NERV is a messy size?

16 hours ago, bewing said:

As far as "landing legs" go, my favorite thing to do with NERVs is to use the Type B swept wings. Fairly low drag during launch & weigh less than 2 girders. I use the offset tool to move the wings down 6 "clicks" until they line up with the engine bell (or a little below). But this rules out the use of fairings for the lander. I just go straight up through the atmosphere as fast as I reasonably can. After you get past the first 35km the fairings are useless anyway.

Cool ship.  Didn't think to use wings like that, although I bet it would add a ton of weight.

12 hours ago, RizzoTheRat said:

Not tried it on Duna but this worked very well for a Minmus/Mun lander.  Rather than having 2 engines, I put 1 engine on the centreline, with a small fuel tank on top, and then built symmetrically from the fuel tank.  2 Mk1 cans means it can collect 2 sets of experiments from every landing, although the crew had to be returned in Mk1 pods to recover their data separately.  Pushing it's fuel dump an then leaving that in orbit it was able to land in every biome on Minmus, transfer to Mun, and then do a further 2 biomes on Mun before needing refueling.  It's main weakness is it probably can't aerobrake.  I did wonder about using a shielded docking port and heat shields on the roof for longer distance missions but that might prove too heavy.

Holy cow that thing is a beauty.  Why does it need so much RCS fuel and Electricity, just for the multiple dockings?  Also, whats the plan for getting Kerbals home with a Reentry on Kerbin?

7 hours ago, tg626 said:

Just an example, this made the landing. Then left the bottom behind on ascent.

...

This is how it got there, assembled in orbit and NERV powered (crazy long burns tho) 

...

Yikes, pictures like yours reminds me of just how bad I am at the game.  Also, I don't recognize all the parts,  can I confirm with you that they are all stock?

 

OK, this is getting very TL;DR, but maybe someone did read all the way to the end.

After reading posts, it got me thinking maybe I am going about it the wrong way.  Instead of having a final stage that goes around on Duna then back home, I can use NERV engines to transfer a much larger ship there, with a smaller lander that goes up and down a few times, then the whole thing turns around to leave.  High efficiency NERV transfer could also mean I don't have to warp 2+ years for windows as well, which is a plus, even if its true to life.

[tg626]

@Giygus it's a mix of stock and KW Rocketry on the mother ship, the lander used the "Gemini-esque" 2 kerbal pod from HGR (Home Grown Rocketry)

[RizzoTheRat]

10 hours ago, Giygus said:

Holy cow that thing is a beauty.  Why does it need so much RCS fuel and Electricity, just for the multiple dockings?  Also, whats the plan for getting Kerbals home with a Reentry on Kerbin?

To be honest it doesn't, it was a bit over engineered, if I build simular in this game it'll have a single RCS tank on the refueller, batteries and solar panels are light though and I'd rather have too many than not enough, especially as I'm using remotetech. 

Lander went to minmus then mun where it met up with another tanker and a pair of return capsules: mk1 cans with a small fuel tank and a spark.

I then built a similar looking one but taller with twin nukes to land 2.5 meter Base modules on the mun.

Edited May 5, 2016 by RizzoTheRat

[Plusck]

10 hours ago, Giygus said:

Why are they "more comfortable and fun"?  Just because the NERV is a messy size?

Size and weight. Since the LV-N is so heavy, it only makes sense to use it if you give it plenty of fuel, which means your lander has to be huge. You can't control that without some serious torque wheels or RCS, which adds more weight. If you use RCS, that makes you dependent on your monoprop. You can't use Vernors because you aren't carrying Ox.

If you use a Terrier, you have gimbal so virtually all maneuvering can be done with that, and command pod torque is enough for the rest. That means that you only need RCS for docking, so you can carry minimal amounts. The lander sits lower, which is convenient when gravity is quite high. And if you want to go a lot further, with the aerospike you can add a ton of fuel yet still have a decent TWR, and use Vernors for RCS control so you only depend on your total fuel load.

This is the design that I used for the Mun but which I got bored flying ; )

It is too heavy for use on Duna (unless you burn off enough fuel before coming in to land), so I messed with it a little just now. I then messed again to give a non-nuke variant.

Admittedly, there are things I would do differently if starting from scratch. Also, looking again at that chemical variant, it would be better with an additional FL-T200 on top of each of the fuel stacks. That would give about 1.2km/s (vacuum) before the drop-tanks were dropped, and about 4.2km/s (ASL Duna) afterwards with a TWR of 1.5.

Admittedly also for the LV-N version, TWR is atrocious to start with. I'd want chutes to land it the first time...

Edited May 5, 2016 by Plusck

[Foxster]

This is kinda fun...

6.3kdV, 1.3 TWR and the wheels make it pretty tolerant to surface hopping. Collect all the science data and store in the capsule before final descent back at Kerbin. 

Craft file: https://www.dropbox.com/s/br470d2hsagsaaf/Duna%20lander%20nuke%201.craft?dl=0

Edited May 5, 2016 by Foxster

[Giygus]

7 hours ago, Foxster said:

This is kinda fun...

6.3kdV, 1.3 TWR and the wheels make it pretty tolerant to surface hopping. Collect all the science data and store in the capsule before final descent back at Kerbin. 

Craft file: https://www.dropbox.com/s/br470d2hsagsaaf/Duna%20lander%20nuke%201.craft?dl=0

Looks really cool, but how in the world does it get fuel to the Engine though?  Also, what is that Air conditioner looking thing on the side of the material studies?

 

Thanks everyone for the advice, I remain in awe of the creativity of this game and those playing it.

OK, I think Plusck got it as good as can be expected.  Going to give it a shot and see what I can do.  After thinking about it for a few days, I think what I am going to do is launch several missions at once.  The lander as one, a refueling pod for the lander (to help with hoping) and 2 separate "duel-transfer-pod" launches.  Hook two NERV powered transfer pods to the lander and refuel, and then get it all to Duna with as little time warp as I can manage.  When done, just bring the lander home.

Edited May 6, 2016 by Giygus

[Superfluous J]

3 minutes ago, Giygus said:

Looks really cool, but how in the world does it get fuel to the Engine though?  Also, what is that Air conditioner looking thing on the side of the material studies?

I'd guess some sort of fuel pump mod, or a lot of right-clicking in flight. And that air conditioner is - I believe - the parachutes, deployed.

[Giygus]

36 minutes ago, 5thHorseman said:

I'd guess some sort of fuel pump mod, or a lot of right-clicking in flight. And that air conditioner is - I believe - the parachutes, deployed.

Oh yeah, that could be the parachutes.

[bewing]

1 hour ago, Giygus said:

Looks really cool, but how in the world does it get fuel to the Engine though?

I don't think right-clicking in flight would do it, because there is no tank in the central stack to receive the fuel. However, I think 3 fuel ducts would do the trick.

[Foxster]

3 hours ago, bewing said:

I don't think right-clicking in flight would do it, because there is no tank in the central stack to receive the fuel. However, I think 3 fuel ducts would do the trick.

Yes, it's just fuel ducts behind the little nose cones from the top tank to the main body. 

And, yes, the "air conditioner" is just a pair of deployed chutes.