Modded interplanatery mothership

[nascarlaser1]

Hi guys!

I'm building a modded interplanetary mothership capable of taking up to 36 Kerbals all over the place, while never having to land to refill (will use other shuttles, or if in a dire issue (stuck heading into a collision with EVE) I will use Hyperedit, but as I said that is only in dire emergencies. I like my shuttles to have more use then actual looks, hence why I'm using mods. My current list of mods will include: KIS/KAS, USI life support, USI core, EPL, various escape pod mods.

I have two questions before I begin assembling my shuttle (I'm building and launching in 1 shot via the space dock mod, so modifications can be made any time before I launch it since my rendezvous skill are absolutely horrible.

1. Do I have to use nerv nuke engines??? I understand they are very efficient, but they are also as slow as heck and my real life time to play is very limited, so I don't want to take too much time flying around.

2. What other mods would you recommend I get for it? I'm in sandbox, so science isn't going to be necessary (this is for my own enjoyment/learning how to build one properly), and I don't care about it looking nice .

Thanks!

p.s. any other suggestions are welcome, since this will be my first interplanetary flight/vehicle in general, let alone with a mothership.

Edited January 15, 2017 by nascarlaser1

[bewing]

Does your mothership have plenty of excess thrust and deltaV (in whatever magic engines it uses for in-system cruising) to haul around a bunch of otherwise-useless oxidizer? If you can drag the oxidizer around with no severe cost to you -- and you want your shuttles to have oodles of power -- then use some high-thrust LFOX engines on them. And even the weight savings for not using nukes will partially counteract the weight penalty of the excess ox and lf that you will need. Using LFOX engines will limit your maximum deltaV in your shuttle, but it shouldn't be a huge problem if your mothership will take them to orbit before dropping them.

[Streetwind]

20 hours ago, nascarlaser1 said:

1. Do I have to use nerv nuke engines??? I understand they are very efficient, but they are also as slow as heck and my real life time to play is very limited, so I don't want to take too much time flying around.

1.) It really, really depends on the exact mission you want to fly.

Adding fuel to a rocket stage doesn't scale indefinitely. There's a hard limit on how much dV a single stage can give you, depending on the Isp of its engine, even if you have the mass of the entire observable universe as fuel. And below that, there's a practical limit for a feasible spacecraft, which is noticably lower still. And due to diminishing returns, there is also a point where pushing a high thrust, low Isp engine to a certain dV value results in less TWR than using a low thrust, high Isp engine to reach the same dV value. Learn about how all of this works over here.

Hence, there are a cases where using a LV-N will give you comparable or better TWR to a classic bipropellant rocket, in combination with higher dV, a smaller/less noodly/more maneuverable vessel, a cheaper vessel, and a lot less effort and cost to launch it.

There are also cases in which a classic bipropellant rocket gives you more TWR while still having enough dV to fulfill your mission.

Into which case does your mission fall? Only you know enough details to determine that! Where do you want to go, and what do you want to do once you get there? How much dV does that take your mothership? Will some of that dV expenditure happen after the shuttles the mothership carries have expended their fuel or dispensed their payload, thereby increasing the mothership's mass fraction and granting it an amount of bonus dV depending on the amount of fuel left at the time? Can the mothership utilize leftover fuel from the shuttles for its own engines on the way home? And so on, and so forth.

It boils down to mission planning. When going to the Mun and other easy-low dV targets, you generally just pick an engine solution first and then throw whatever necessary at it to make it work. But doing massive interplanetary combo missions and tours is more complicated. You have to do some up-front analysis first to figure out a good solution to start building upon. Yes, it may sound difficult. But this is rocket science, after all. What did you expect?

 

2.) If you're open to further modding, look into high-tech propulsion addons. Be aware though: just like in real life, high-tech propulsion in KSP trends strongly towards the low thrust, high Isp approach. And because just adding a random engine with inflated stats is boring, they trend towards adding additional layers of realism and/or complexity as well. For example, dealing with the downsides of liquid hydrogen (huge tank size for equivalent reaction mass, boiloff prevention schemes), or requiring massive power generation, in return for an engine that performs above what you get in stock KSP. Two things you could look into would be Kerbal Atomics and Deep Space Exploration Vessels. I would link Near Future Propulsion as well, since I help out with it, but 1.) the forum ate the thread and Squad hasn't managed to restore it yet, and 2.) those engines require even more patience than the LV-N does. Finally, if you have leftover science, consider Kerbal R&D, which lets you spend science on individual part performance upgrades.

Of course, if you can't really find an engine that suits your needs, you can use a Module Manager patch to improve the stats of any engine you like to the level where you need them. Remember, there is no cheating in a singleplayer game! You could just roleplay that that engine is the culmination of your space program's science efforts, created specifically for this mothership...?

Edited January 16, 2017 by Streetwind

[nascarlaser1]

2 hours ago, Streetwind said:

1.) It really, really depends on the exact mission you want to fly.

Adding fuel to a rocket stage doesn't scale indefinitely. There's a hard limit on how much dV a single stage can give you, depending on the Isp of its engine, even if you have the mass of the entire observable universe as fuel. And below that, there's a practical limit for a feasible spacecraft, which is noticably lower still. And due to diminishing returns, there is also a point where pushing a high thrust, low Isp engine to a certain dV value results in less TWR than using a low thrust, high Isp engine to reach the same dV value. Learn about how all of this works over here.

Hence, there are a cases where using a LV-N will give you comparable or better TWR to a classic bipropellant rocket, in combination with higher dV, a smaller/less noodly/more maneuverable vessel, a cheaper vessel, and a lot less effort and cost to launch it.

There are also cases in which a classic bipropellant rocket gives you more TWR while still having enough dV to fulfill your mission.

Into which case does your mission fall? Only you know enough details to determine that! Where do you want to go, and what do you want to do once you get there? How much dV does that take your mothership? Will some of that dV expenditure happen after the shuttles the mothership carries have expended their fuel or dispensed their payload, thereby increasing the mothership's mass fraction and granting it an amount of bonus dV depending on the amount of fuel left at the time? Can the mothership utilize leftover fuel from the shuttles for its own engines on the way home? And so on, and so forth.

It boils down to mission planning. When going to the Mun and other easy-low dV targets, you generally just pick an engine solution first and then throw whatever necessary at it to make it work. But doing massive interplanetary combo missions and tours is more complicated. You have to do some up-front analysis first to figure out a good solution to start building upon. Yes, it may sound difficult. But this is rocket science, after all. What did you expect?

 

2.) If you're open to further modding, look into high-tech propulsion addons. Be aware though: just like in real life, high-tech propulsion in KSP trends strongly towards the low thrust, high Isp approach. And because just adding a random engine with inflated stats is boring, they trend towards adding additional layers of realism and/or complexity as well. For example, dealing with the downsides of liquid hydrogen (huge tank size for equivalent reaction mass, boiloff prevention schemes), or requiring massive power generation, in return for an engine that performs above what you get in stock KSP. Two things you could look into would be Kerbal Atomics and Deep Space Exploration Vessels. I would link Near Future Propulsion as well, since I help out with it, but 1.) the forum ate the thread and Squad hasn't managed to restore it yet, and 2.) those engines require even more patience than the LV-N does. Finally, if you have leftover science, consider Kerbal R&D, which lets you spend science on individual part performance upgrades.

Of course, if you can't really find an engine that suits your needs, you can use a Module Manager patch to improve the stats of any engine you like to the level where you need them. Remember, there is no cheating in a singleplayer game! You could just roleplay that that engine is the culmination of your space program's science efforts, created specifically for this mothership...?

 

17 hours ago, bewing said:

Does your mothership have plenty of excess thrust and deltaV (in whatever magic engines it uses for in-system cruising) to haul around a bunch of otherwise-useless oxidizer? If you can drag the oxidizer around with no severe cost to you -- and you want your shuttles to have oodles of power -- then use some high-thrust LFOX engines on them. And even the weight savings for not using nukes will partially counteract the weight penalty of the excess ox and lf that you will need. Using LFOX engines will limit your maximum deltaV in your shuttle, but it shouldn't be a huge problem if your mothership will take them to orbit before dropping them.

Thanks guys! For the payload, all I'm carrying with me are the Kerbals, LS supplies for them, KIS/KAS gear, some rocket parts and the orbital Launchpad, and finally the lf/ox from the 12-14 (don't remember the exact number) of the orange tanks. The landers, satellites and any other external vehicles that are required will be built on the Launchpad via EPL in orbit of the planet, then the crew will be transferred to them and landed separately. The plan is to never let the mothership return to Kerbin orbit for long periods of time is for refuels and for crew refuels, since many (if not all ) of the vehicles will be 1 shot, due to only ever landing on the Mun and Minimus. I do have KER installed, so later today/some time this week I can get you the stats for it if you want/need them, along with the WIP craft file (will need hyperedit to get the ship in orbit though unless you have the spacedock mod). I don't even plan on letting the mothership enter a suborbital trajectory of any planet, moon, or gas giant.

 

Thanks again!