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Best Mun Craft?


Andrew Ridgely
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I have some truly incredible-looking Mun exploration vehicles. Unfortunately I have recently lost my screenshots folder, but I have a new design that I'm working on for going to the Mun with the New Horizons mod (in which, amongst other changes, Kerbin and the Mun are now in orbit around the gas giant Sonnah). I believe it takes somewhat more delta-v than a standard Mun mission, and it will certainly make for an interesting vehicle especially since I plan on bringing a rover. I'll post some pictures here when I have some.

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Scorpio 3:

SCWM1KI.jpg

This is a Mun mission with the New Horizons planet pack. Kerbin and Mun are both in orbit around the gas giant Sonnah, although I found out that a Mun mission takes approximately the same amount of delta-v as it does in the stock system.

sag0fEW.jpg

The fairing at the top of the rocket is actually two individual fairings. One is attached to the launch abort system and only covers the command pod (the LAS is bound to the abort key) and the other fairing covers the lander and service module.

NStLMwF.jpg

The launch vehicle is my standard Jool 3C, which features the nicest looking booster separation of any rocket I've created.

VdvLxuM.jpg

Once circularized in a 150km orbit (using the Jool 3C upper stage that doubles as the Mun transfer stage) the fairing and LAS are jettisoned to reveal the command/service modules and Munar lander.

pjX8VAX.jpg

Here's the orbital configuration of Kerbin and the Mun in relation to Sonnah.

3F5Q5kg.jpg

The spacecraft will circularise using the Jool 3C upper stage, and then that stage will de-orbit itself.

ULkQyge.jpg

I'm very pleased with this lander design in particular. I actually have an idea for a Tylo lander with a similar (but more powerful) design.

j6jrvxE.jpg

The initial intended payload was a rover, but I decided to play around with the Surface Experiment Package mod instead. All of those experiments were stored on the two KIS storage lockers on the sides of the lander. Scorpio 6 will probably return to the Mun with a rover and a larger lander.

lOzChkI.jpg

The lander is similar to the Apollo lunar landers in many ways, including the descent/ascent module system.

0O9eYGE.jpg

The ascent module is propelled by an Iota engine from the Vx Series II engine pack. It's a good engine to use because it can consume either LF+O or monopropellant, meaning that if it runs short of liquid fuel, it still has some room for error using the monopropellant stored on the lander.

ooYpJsE.jpg

Here the Munar ascent module is docking to the command/service module. The service module has plenty of delta-v to return the crew safely to Kerbin, where the capsule aerobrakes into a landing or splashdown (on this mission it was a splashdown).

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On 9/6/2016 at 1:07 PM, eloquentJane said:

Scorpio 3:

SCWM1KI.jpg

This is a Mun mission with the New Horizons planet pack. Kerbin and Mun are both in orbit around the gas giant Sonnah, although I found out that a Mun mission takes approximately the same amount of delta-v as it does in the stock system.

sag0fEW.jpg

The fairing at the top of the rocket is actually two individual fairings. One is attached to the launch abort system and only covers the command pod (the LAS is bound to the abort key) and the other fairing covers the lander and service module.

NStLMwF.jpg

The launch vehicle is my standard Jool 3C, which features the nicest looking booster separation of any rocket I've created.

VdvLxuM.jpg

Once circularized in a 150km orbit (using the Jool 3C upper stage that doubles as the Mun transfer stage) the fairing and LAS are jettisoned to reveal the command/service modules and Munar lander.

pjX8VAX.jpg

Here's the orbital configuration of Kerbin and the Mun in relation to Sonnah.

3F5Q5kg.jpg

The spacecraft will circularise using the Jool 3C upper stage, and then that stage will de-orbit itself.

ULkQyge.jpg

I'm very pleased with this lander design in particular. I actually have an idea for a Tylo lander with a similar (but more powerful) design.

j6jrvxE.jpg

The initial intended payload was a rover, but I decided to play around with the Surface Experiment Package mod instead. All of those experiments were stored on the two KIS storage lockers on the sides of the lander. Scorpio 6 will probably return to the Mun with a rover and a larger lander.

lOzChkI.jpg

The lander is similar to the Apollo lunar landers in many ways, including the descent/ascent module system.

0O9eYGE.jpg

The ascent module is propelled by an Iota engine from the Vx Series II engine pack. It's a good engine to use because it can consume either LF+O or monopropellant, meaning that if it runs short of liquid fuel, it still has some room for error using the monopropellant stored on the lander.

ooYpJsE.jpg

Here the Munar ascent module is docking to the command/service module. The service module has plenty of delta-v to return the crew safely to Kerbin, where the capsule aerobrakes into a landing or splashdown (on this mission it was a splashdown).

 

how do you get so much delta-v with that one tank??? I seem to have so many tanks, yet not enough delta-v.

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19 minutes ago, Andrew Ridgely said:

how do you get so much delta-v with that one tank??? I seem to have so many tanks, yet not enough delta-v.

You haven't specified enough for me to be able to help out a lot, but I'll try to cover everything that might be causing you difficulty with regards to delta-v.

Firstly, which tank are you referring to? The service module tank (with Sigma engine), the tanks on the lander (Iota engine for ascent module, Terrier for descent), the Jool upper stage tank (with Rhino engine), or the Jool 3C tanks (with a Pulsar and 4 Swivels, and also boosted by 4 heavy SpaceY SRBs with their own fuel)? Each one has a different amount of fuel and a different engine configuration, and some are vacuum-optimised whereas others (primarily the Jool 3C launch stage) are designed to function most effectively in Kerbin's atmosphere. Also, the Scorpio 3 vehicle is modded, but it's stock balanced so it shouldn't be that far off from what the stock game can achieve.

The amount of delta-v you get from a quantity of fuel depends on the payload mass, and also the efficiency of the engine. You wouldn't want to be using a Rhino or a Poodle as a first stage engine on Kerbin for example, because those are only efficient in low-pressure environments. Alternatively, sea-level lifting engines like the Twin Boar are terrible in space compared to the more efficient alternatives.

And plus, different payload masses mean that the same engine/fuel tank configuration will result in different amounts of delta-v. The Jool 3C launch vehicle that I used on the Scorpio 3 mission had I think around 2km/s more delta-v than it usually does, because it's designed for a payload about 10 tonnes heavier than the Scorpio 3 command/service and lander modules. However, it's only designed to get that larger payload to Kerbin orbit, and the smaller Scorpio 3 payload is approximately the right mass for the Jool 3C to get to the Mun (It's actually slightly more but I like to have a lot of room for error).

Finally, it may not be delta-v that's your problem. If you're inexperienced, it's possible that you may be using an inefficient ascent profile. It takes around 3500m/s for the average pilot to get into Kerbin orbit with a well-executed gravity turn (I think that can be brought down to 3200m/s, but my personal record is around 3450m/s). However, if your ascent profile is more along the lines of "straight up until 20km because the rocket is apparently uncontrollable in the lower atmosphere" you're going to have problems with efficiency and waste a lot of fuel and delta-v.

If you are still struggling, I could start a new thread to explain my design process in a lot of detail and go over how to obtain the required delta-v values for a mission. But I'd rather avoid derailing this thread too much because it seems to be intended for showing off designs rather than troubleshooting.

Edited by eloquentJane
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3 minutes ago, eloquentJane said:

You haven't specified enough for me to be able to help out a lot, but I'll try to cover everything that might be causing you difficulty with regards to delta-v.

Firstly, which tank are you referring to? The service module tank (with Sigma engine), the tanks on the lander (Iota engine for ascent module, Terrier for descent), the Jool upper stage tank (with Rhino engine), or the Jool 3C tanks (with a Pulsar and 4 Swivels, and also boosted by 4 heavy SpaceY SRBs with their own fuel)? Each one has a different amount of fuel and a different engine configuration, and some are vacuum-optimised whereas others (primarily the Jool 3C launch stage) are designed to function most effectively in Kerbin's atmosphere. Also, the Scorpio 3 vehicle is modded, but it's stock balanced so it shouldn't be that far off from what the stock game can achieve.

The amount of delta-v you get from a quantity of fuel depends on the payload mass, and also the efficiency of the engine. You wouldn't want to be using a Rhino or a Poodle as a first stage engine on Kerbin for example, because those are only efficient in low-pressure environments. Alternatively, sea-level lifting engines like the Twin Boar are terrible in space compared to the more efficient alternatives.

And plus, different payload masses mean that the same engine/fuel tank configuration will result in different amounts of delta-v. The Jool 3C launch vehicle that I used on the Scorpio 3 mission had I think around 2km/s more delta-v than it usually does, because it's designed for a payload about 10 tonnes heavier than the Scorpio 3 command/service and lander modules. However, it's only designed to get that larger payload to Kerbin orbit, and the smaller Scorpio 3 payload is approximately the right mass for the Jool 3C to get to the Mun (It's actually slightly more but I like to have a lot of room for error).

Finally, it may not be delta-v that's your problem. If you're inexperienced, it's possible that you may be using an inefficient ascent profile. It takes around 3500m/s for the average pilot to get into Kerbin orbit with a well-executed gravity turn (I think that can be brought down to 3200m/s, but my personal record is around 3450m/s). However, if your ascent profile is more along the lines of "straight up until 20km because the rocket is apparently uncontrollable in the lower atmosphere" you're going to have problems with efficiency and waste a lot of fuel and delta-v.

 

Thank you.  It is probably my choice of parts and also my piloting skills (they aren't that good yet).  I will definitely pay more attention to my mass, engine choice, and fuel efficiency.  Again, thank you.

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Just now, Andrew Ridgely said:

Thank you.  It is probably my choice of parts and also my piloting skills (they aren't that good yet).  I will definitely pay more attention to my mass, engine choice, and fuel efficiency.  Again, thank you.

MechJeb may also be of use to you, if you're not averse to using mods. It'll show you delta-v information, and also the thrust-to-weight of your engines at whatever destination you choose. And I have decided also that I'll put together a thread (probably tomorrow) going over my vehicle design process, particularly as an aid to players such as yourself who have difficulty with achieving various aspects of vehicle design (such as delta-v requirements).

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This guy was supposed to get a Kerbal to LKO from the surface on the cheap, and then return a Kerbal from orbit to the ground (ahhh, pre-1.0-atmo. I sometimes miss you). In the early stages of building it I misread my dV numbers and overbuilt a tad. So I tried to see how far it would go.

IIRC it couldn't land, or even get back to Kerbin, but it did get a flyby :)

boyelroy.jpg

 

Edited by 5thHorseman
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1 hour ago, 5thHorseman said:

This guy was supposed to get a Kerbal to LKO from the surface on the cheap, and then return a Kerbal from orbit to the ground (ahhh, pre-1.0-atmo. I sometimes miss you). In the early stages of building it I misread my dV numbers and overbuilt a tad. So I tried to see how far it would go.

IIRC it couldn't land, or even get back to Kerbin, but it did get a flyby :)

boyelroy.jpg

 

This made my day :D

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@Andrew Ridgely, based on your comments here, I am going to go out on a limb and guess you are new(ish) to the game and looking to improve your Mun landing missions.  Great!  You have come to the right place.  

Based on your delta-v query, one piece of advice I can give (assuming you are not already doing so) is to give your rockets separate modules for transition and landing.  Getting to Munar orbit requires a certain amount of delta-v but not a lot of finesse.  By contrast, getting down to the Munar surface and back to orbit requires less delta-v, but a lot more finesse.  If you are carrying a bunch of big tanks and big engines with you that you used to transition to the Mun, those are going to be extra mass that will degrade your performance on descent and ascent, increasing the delta-v consumption for that stage of the mission.  If you can manage to separate yourself from the (partially empty) big transition fuel tanks and heavier thrusters, then you can get away with a lander that has a much smaller engine and can go further on less fuel.  If you are good at docking, you can even re-attach your transition module to your lander and use the remainder of its fuel getting back home.  

Note how @eloquentJane's design includes a launch vehicle (the big heavy rockets to get off the pad) a transition module (the big tank and engine) and a landing module (the smaller cabin with the tiny engine and fuel tanks.)  A multi-part design like this can get a lot better fuel efficiency than something that must both perform a transfer from LKO to the Mun and land and return all in one non-separable ship.  

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The Super Mun Overkill VI. Guess what it is. 

It's a huge crusier. The original name was the Super Over Engineered Mun Ship VI. It went to the Mun, Minmus, Dres (because Dres it the best), Bop, and almost back to Kerbin, then I realized I didn't have a heat shield or any escape pods. I probably just could have slowed into orbit, but I was getting kinda bored. So I just impacted my Mun Base with it. I pretend I made a new crater on the Mun, even though I didn't actually. Because it got way farther than the Mun, and because the end of the mission killed a lot of Kerbals, I renamed it the Super Mun Overkill. This was back in 1.0.5. I think the two dudes who were out in the rover at the time of the impact are still stuck on the Mun... 

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2 minutes ago, max_creative said:

The Super Mun Overkill VI. Guess what it is. 

It's a huge crusier. The original name was the Super Over Engineered Mun Ship VI. It went to the Mun, Minmus, Dres (because Dres it the best), Bop, and almost back to Kerbin, then I realized I didn't have a heat shield or any escape pods. I probably just could have slowed into orbit, but I was getting kinda bored. So I just impacted my Mun Base with it. I pretend I made a new crater on the Mun, even though I didn't actually. Because it got way farther than the Mun, and because the end of the mission killed a lot of Kerbals, I renamed it the Super Mun Overkill. This was back in 1.0.5. I think the two dudes who were out in the rover at the time of the impact are still stuck on the Mun... 

And... That is a mouthful. :D

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19 hours ago, Fearless Son said:

@Andrew Ridgely, based on your comments here, I am going to go out on a limb and guess you are new(ish) to the game and looking to improve your Mun landing missions.  Great!  You have come to the right place.  

Based on your delta-v query, one piece of advice I can give (assuming you are not already doing so) is to give your rockets separate modules for transition and landing.  Getting to Munar orbit requires a certain amount of delta-v but not a lot of finesse.  By contrast, getting down to the Munar surface and back to orbit requires less delta-v, but a lot more finesse.  If you are carrying a bunch of big tanks and big engines with you that you used to transition to the Mun, those are going to be extra mass that will degrade your performance on descent and ascent, increasing the delta-v consumption for that stage of the mission.  If you can manage to separate yourself from the (partially empty) big transition fuel tanks and heavier thrusters, then you can get away with a lander that has a much smaller engine and can go further on less fuel.  If you are good at docking, you can even re-attach your transition module to your lander and use the remainder of its fuel getting back home.  

Note how @eloquentJane's design includes a launch vehicle (the big heavy rockets to get off the pad) a transition module (the big tank and engine) and a landing module (the smaller cabin with the tiny engine and fuel tanks.)  A multi-part design like this can get a lot better fuel efficiency than something that must both perform a transfer from LKO to the Mun and land and return all in one non-separable ship.  

 

Yeah, I am new haha :)   Thanks for the tips!  I will definitely use them when I play!

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5 hours ago, Andrew Ridgely said:

Yeah, I am new haha :)   Thanks for the tips!  I will definitely use them when I play!

If you know how to make transfer burns, you should know how to dock.  The way I first landed on the mun and came back was using an Apollo style mission.  Using one stage is going to be more efficient but also harder, since you have to balance a stack of fuel tanks.  If you take an Apollo style mission you'll want asparagus staging on your lander as well as a two part lander, where one part lands and another part takes off (essentially leaving half of the craft on Mun).  Another thing to keep in mind is the size of your engine.  A huge Mainsail is not going to be very good for landing simply because you need huge landing gear.  A Poodle, Terrier, or multiple Sparks will fare better.  Or you may just slap on some radial engines and be done with it.  

 

Good luck, and don't forget science!

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As another piece of advice @Andrew Ridgely, I cannot stress enough how important having a wide base is for a Mun lander.  You want to keep your center of gravity low and your landing legs far apart.  A tall, narrow craft is going to have some serious trouble staying upright on touchdown.  

Most of the common Mun landers I have seen tend to achieve this by instead of having a big central tank and a single powerful engine, they will tend to have several smaller tanks, each with a less powerful engine, and mount them radially around a command module.  This tends to result in a shorter, fatter lander, and is a fairly reliable design.  

As another note, the most effective Mun landers tend to be the lightest.  Carefully consider the parts you choose, and try to shave off as much weight as you can while still meeting your mission requirements.  Does it really need four engines?  Could it do it with two instead?  Do I really need those extra fuel tanks?  Sometimes reducing the weight can lead to a net increase in delta-v even if it means sacrificing some fuel.  A lighter lander will not only be easier to land, but it will be easier to get into orbit and transfer to the Mun.  Every ounce saved on the lander is worth several ounces more fuel you can spend getting it there in the first place.  

Oh, and do not forget a pair of landing lights facing downward on the lander.  They are absolutely essential for landing on the night side of the Mun, and while I do not recommend a night touchdown unless you are very confident in your ability to do a Mun landing, the landing lights are helpful in other ways.  As you get near the ground, the landing lights will start shining on the surface, and the area they light up gets narrower and brighter the closer you get to the Munar regolith.  This gives you an excellent visual feedback as to how close you are to the surface, how quickly you are coming down, and whether the surface is level with your descending lander.  This can allow you to make quick corrections in your velocity at just a glance and avoid getting caught off guard by the scale of the surface landmarks.  

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On 9/11/2016 at 1:18 AM, TwinKerbal said:

If you know how to make transfer burns, you should know how to dock.  The way I first landed on the mun and came back was using an Apollo style mission

Docking isn't necessarily an easy thing to learn. I learned to do precision landings before I figured out orbital rendezvous. The process is simple once you know it and probably simple for some people to learn, but for others it takes a while to get used to.

I imagine it's more common for people's first Mun landings to use a direct ascent profile rather than Munar orbit rendezvous, because getting 7km/s in a single-stack vehicle is a far simpler task. In reality a direct ascent profile wasn't really feasible, but in KSP it's definitely doable. It takes a significant amount more fuel, but the simplicity generally outweighs that for an inexperienced player. And due to the relative lack of complexity, I personally would recommend it for early Mun landings. However, a Munar orbit rendezvous mission is definitely something that is good to attempt once confident with docking, because using a direct ascent profile becomes far more difficult when travelling to destinations outside of Kerbin's SOI (well, it's fine for one-way missions but not easily doable if you want to return).

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On 9/3/2016 at 4:19 PM, Andrew Ridgely said:

Hey everyone!  What is your best craft (that you made) for going to the mun?

I'm still pretty happy with my second K Prize submission, in which a tiny one-crew lander gets to orbit in the cargo compartment of a small spaceplane, transfers to and lands on Mun, and returns to rendezvous for a landing on the runway.

 

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