[0.19.1] Orbital Propellant Depot Olympus II

[Temstar]

A long time ago (or not, forum TIME PARADOX), when KSP didn't yet have official support for docking I built a propellant depot using the docking mods then available. I got some pretty positive responses for it.

These days with stock docking people are building huge propellant depots that dwarf the original Olympus. Nevertheless every now and then I get people asking me if I would release an updated version of Olympus. So here it is: Orbital Propellant Depot Olympus II, now with some new tricks up its sleeves...

Olympus II features:

• 8000L of fuel + oxidiser, 1500L of monopropellant, 2800L of Xenon and 1705 electrical charge
  
• four standard docking ports for refuelling crafts
  
• for jr docking ports for small refuelling crafts
  
• built in small orbital manoeuvring engines
  
• two man capacity
  
• probe core and solar panels for autonomous control
  
• two heavy duty docking ports fore and aft for expansion modules
  
• Zenith VII launch vehicle for placing in LKO
  

Note: action group 2 toggles the three small orbital engines on and off.

Let's have a look at the Olympus II launch process:

Olympus II at launch. The original Olympus used some fancy engineering to put a custom made launch vehicle underneath and had features like a fuel lines that went up to the depot from the booster rocket so the depot could fire it's radial engines in additional to the booster's asparagus core engines once all the boosters are gone to accelerate faster. This time around since I have the Zenith rocket family available I simply designed the station (and used only three R24-77 engines, instead of the big hulking Rockomax radial), weigh it up in Engineer Redux and put an appropriate sized Zenith booster underneath and I have a finished product.

A closer look at the clustered engines on the LV with two pairs of boosters gone. Each of the six boosters are powered by three LV-T30 and a LV-T45, the core stage of the asparagus is powered by four LV-T30 and three LV-T45.

Last pair of asparagus staged boosters jettison in the upper atmosphere. The core stage has something like 2000m/s of delta-V and is responsible for orbital insertion.

Payload release. Notice all resources on Olympus II are still full - I've designed it so that the rocket should have enough delta-V to place the depot in LKO without having to fire up the depot's engines at all.

When you have a space station / propellant depot, you don't want spent rocket stages floating around in the same orbit as it. As with all members of the Zenith rocket family Zenith VII has a smart core stage which is equipped with probe core, electrical and RCS system for deorbit burn to clean up after itself.

As they say "once you build a road the cars will come". With Olympus II in orbit and open for business the first wave of customers showed up.

Now if that was all there was to the propellant depot then I wouldn't have shared it considering the plenitude of other well made depot designs around. But Olympus II has one more important feature that I think sets it apart from others and it has to do with those funny looking 4x docking ports at the front and back:

More on these docking ports and the modular expansion modules in my next post

Craft files:

OPD Olympus II - http://www./download.php?20ii5h5c9avclc7

HEM Poseidon - http://www./download.php?611g91f11ksnadl

PME Zeus - http://www./download.php?ae08i3ipcom83ep

Downmass Tug - http://www./download.php?gff7ttebe15a6mt

[Temstar]

When it comes to expansion modules on space station the foremost problem is always connection strength of the docking ports. A single docking port is okay for docking between small spacecrafts or between a small spacecraft and a station, but any serious space construction effort requires stiffer connections. The solution most people go for is multiple docking ports. But the thing I don't like about using multiple docking ports is their setup. Setting them up in the VAB by eye will mean there's always going to be small errors with alignment with the most common result in orbit being some of the docking ports connect while some refuse to engage when you dock. Fortunately now that subassembly saver/loader is available we finally have a way to build pixel perfect docking solutions:

So with that bit of engineering resolved I started thinking about what modules Olympus II will need.

Habitation Extension Module Poseidon

Well first of all, seen as we already have an installation in orbit we might as well get some more habitation to go with it. So let's say a 6 man craft with some small orbital manoeuvring engines, docking capable and with some big solar panels to power all the scientific gizmo's and flat screen TVs and playstations inside. When you put these requirements together you get something like this:

That's right, it's really a fully equipped small space station. Only unlike Salyut its propulsion unit is a lot more powerful and it has delta-V to change orbit to dock with a target. This means that should anything bad (eg, spacecraft accidentally ramming Olympus) happen it can undock from the propellant depot in a hurry and serve as a life boat, particularly if we also add re-entry capability to this spacecraft.

The end result is this:

Habitation Extension Module Poseidon, holding 6 Kerbals. Heavy quad docking port on one end and normal single docking port on the other. Four R24-77 engines for orbital manoeuvring. Two small solar panels and two giganator panels for more power than you know what to do with.

Launch of Poseidon atop of a Zenith II rocket.

Payload release. As with other members of the Zenith rocket family, Zenith II has a "smart" core stage designed to deorbit itself after payload release to ensure no space junk. For Poseidon solar panel deployment use action group 1.

Poseidon coming into dock with Olympus II. To open the shielded docking ports use action group 3. Action group 2 can be used to toggle on and off the main engines, useful once you are docked with something.

Crew transfer between Olympus II and Poseidon. One nifty feature is the matching telescopic ladders on Olympus II and Poseidon. If you dock them front to front and with the correct alignment you can extend those ladders for no-jetpack crew transfer between the three crewed modules.

Planetary Manoeuvring Engine Zeus

I set some pretty strict rules for myself when it comes to using NTR rockets. The idea being Kerbals are much like us humans and are not too keen on having high powered nuclear reactors flying overhead without some kind of plans on how to make sure they doesn't fall back down on their head. I particularly will not design spacecraft powered by nuclear engine that is intended for Kerbin re-entry. Thus the idea of a modular nuclear powered tug is attractive - once launched the tug can be docked to whatever spacecraft that need efficient deep space engine, the once the mission is over the tug can be detached, refuelled and then reused later on for another mission. This idea thus became the basis of Planetary Manoeuvring Engine Zeus.

Zeus launch. Unlike other payloads I elected to build a custom launch vehicle around Zeus rather than use a prebuilt launcher underneath. The reason is two folds:

1. That's an awful lot of thrust that I'm not using if I don't fire the Zeus at lift off

2. Putting a decoupler underneath a cluster of LV-N when LV-N has those side shredding engine shrouds means you're building an accident looking for a place to happen. A shrouded centre LV-N engine will most likely blast away all the surrounding engine upon decoupling.

Zeus burning for orbit. With six LV-N and 3200L of bipropellant Zeus actually has slightly better than 1 TWR at Kerbin surface fully fuelled. With max fuel level it has something absurd like 7100m/s of delta-V. It's powered by three RTGs.

Zeus coming into dock with Olympus. Since Zeus only has one probe core for maxRot it has very little altitude control with RCS off. So when docking I always leave RCS on. Then once I'm aligned with the target I switch on ASAS on both ships to fix the orientation and just use Zeus's RCS for translation.

Zeus and Poseidon, docked with Olympus II

******

Now that I have the whole Zeus - Olympus II - Poseidon stack assembled, I felt it was time for a trip:

Trans-munar injection burn

Success! The whole station successfully made it to Mun orbit, with two docked spacecrafts in tow too.

The best thing about a modular design is that the different parts can be rearranged to do other things. With the propellant depot successfully placed in Mun orbit and all system checked out, I decided to bring the crew back. Undocking Poseidon and Zeus from Olympus II and joining them together results in a new deep space spacecraft.

Trans-Kerbin injection with the newly assembled Poseidon-Zeus spacecraft.

Aerobraking into LKO. Remember folks if you're going to aerobrake Poseidon use action group 1 to retract the solar panels before you hit the atmosphere. With aerobraking I figure that rocket nozzles make a pretty good heat shield substitute. After all it's a structurally strong part that's designed to endure high temperature and high gas pressure - not all that dissimilar to reentry.

Separation between Zeus and Poseidon.

Separation between Poseidon's habituation module and service module.

Reentry and parachute release. I like to pretend that the shielded docking ports are re-entry hardened compared to the regular ones.

Crew upon return. Although the habitation module can survive hard touch down as demonstrated here I would still recommend splashdown if possible.

******

Now then, it's all well and good if we have Zeus floating up there in LKO waiting for a mission. But if there's no mission for it in the foreseeable future the public would probably want the space program to retrieve it and safely bring it down rather than have this Sword of Damocles hanging over their head every day. For such situations I've come up with an answer too:

Presenting: Downmass Tug. A space tug specifically designed to retrieve Zeus and other heavy quad docking port equipped vessels.

Downmass Tug docking with Zeus

De-orbit burn. There is a trick here with the deorbit burn - if you just want to bring the combination down then make sure you turn off the tug's engine before firing up Zeus. Alternatively if you have a lot of fuel onboard and want to burn some up to lighten the craft then you can leave the tug's engine on to fight Zeus's engine. Zeus will still overpower the tug but the long burn with engines fighting each other will quickly burn up the excess fuel.

Re-entry and parachute deployment. Zeus is specially strengthen to be able to survive the violent jolt of parachute becoming unreefed. The heavy duty docking ports are also strong enough to hold together.

Firing Zeus's engine before splash down to soften the impact. I recommend a splashdown speed no greater than 5m/s.

Unfortunately after splash down the combination tipped over and broke. Fortunately upon close inspection it was only the Downmass Tug that was destroyed. Zeus was intact and all the nuclear engines are still attached so I would assume there was no nuclear material leak - a successful retrieval!

Edited April 22, 2013 by Temstar

[Climberfx]

Good Job! LP

I like it!

[Giggleplex777]

Will you post your 3-kerbal orbital launch system? I want to compare it to m own.

[astropapi1]

Could you upload the .craft file for the 3-crew orbiter? The one with the two solar panels, mines don't look so cool. I'm designing a falcon heavy with the KW rocketry, and that orbiter would fit perfectly on the payload bay!

[KissSh0t]

I don't understand how you are putting 4 rockets on the red fuel tank... and then... the tail connector? sideways on the red fuel tank..

I'm trying to do it myself but can't figure it out :/

[Giggleplex777]

I don't understand how you are putting 4 rockets on the red fuel tank... and then... the tail connector? sideways on the red fuel tank..

I'm trying to do it myself but can't figure it out :/

He is using the small cubic trusses and part rotation.

[dennislinux]

He is using the small cubic trusses and part rotation.

cool! why u no add kethane??

[Giggleplex777]

The only thing my orbiter lacks that yours have are lights!

[ReconXPanzer]

Lovely Station, Excellent Job

[KissSh0t]

I figured out how you did the rocket nozzles xD

I downloaded your ship and took it apart... then spent an hour trying to make the rocket nozzle on mine like yours... my goodness that was hard///

[Temstar]

By popular request: Crew Excursion Vehicle Demeter II:

Being designed as a space taxi ala Soyuz, Demeter II is equipped with a powerful LES system to ensure crew safety in the event of launch vehicle failure, capable of outrunning the launch vehicle during all stages of the burn. When LES is triggered the following happens:

• launch vehicle liquid fuelled engine shutdown
  
• core stage retro-rocket fire
  
• deploy SRB recovery chute as drag chute to slow the booster down (in the event of an abort before SRB jettison). The SRB is not decoupled from the rocket itself since the dead weight of the rocket serve as ballast to slow the SRBs down
  
• emergency separation between spacecraft and rocket
  
• LES abort motor fire
  
• Spacecraft SM engine fire
  

Once the spacecraft is clear of the rocket and the LES abort motor have stopped firing. Use action group 2 to jettison the LES tower (tower jettison has two additional Sepratrons dedicated for it, so you can fire even if the six abort motors are empty).

On the other hand if things go well, SRBs are jettisoned at just below 5km. A cool feature is the liquid fuel tanks above the SRBs feeding the core stage - those have been fine tuned so they run out just before SRB burn out. Thus at the moment SRBs are jettisoned the core stage is still nearly fully fuelled.

LES tower jettison after start of gravity turn. You can do this with either stage 4 or action group 2.

A closer look at the core stage engines. The cluster is three LV-T30 + one LV-T45.

Payload release. Upon release the core stage has three retrograde Sepratrons that will fire to slow it down for deorbit, but there's only so much three Sepratrons can do so I still recommend releasing the spacecraft when you're either suborbital or just barely orbital to ensure the rocket burns up by going below 23km.

A closer look at the Demeter II spacecraft. Note the service module propulsion system - two LV-909 built together using engine clustering.

Craft file: http://www./download.php?yov912e8qhxrznb

Addendum: I increased retro-Sepratrons from three to six, given their weight decrease in 0.19 patch.

Edited April 20, 2013 by Temstar

[Giggleplex777]

I think my CEV has better performance and more features than yours, but it doesn't have recovery parachutes.

Edit:

Here's the "Lite+" variant (I made a whole series of them while the forums where down ).

It weighs 95 tons and has the following features (and a few more):

-Probed command pod

-Backup parachute

-Soft landing retro rockets inside the command pod (also serves as a secondary abort system)

-docking light

-Backup battery and solar panel

-1.5 stage core booster

-Cool-looking LES tower

Edit2: Here's a soft landing system demo

Edited April 21, 2013 by Giggleplex777

[Temstar]

I think my CEV has better performance and more features than yours, but it doesn't have recovery parachutes.

Oh, so it lands tail first on pure rocket thrust? It's a pretty good idea in KSP but would be hard to come up with a heat shield solution in real life to be able to get the whole thing to survive re-entry.

I have three space taxies I use in my space program. Demeter is the "middle of the road" one of the three with 1442m/s delta-V, used for general purpose missions with in Kerbin SOI, similar to Orion.

For very large missions like Apollo style landings or Interplanetary trips I use the CEV Apokee IV with high TWR SM and 2117m/s of delta-V:

Here it is integrated into the Apokee Munar Sortie stack:

So this is like my take on a Mars capable version of Orion.

For cases where I only need to go up to LKO to bring crew back (station, interplanetary ships coming back, etc) I use a light weight Crew Return Craft Dragonfly (ala SpaceX's Dragon) with 542m/s of delta-V:

You can see a Dragonfly docked to Olympus II in some of the screenshots.

[Giggleplex777]

I got the inspiration from the Dragonrider concept (or Soyuz, I guess). Hiding the engines inside looked better then on the side.

Edit: Here's the orbital stage of the Lite and Lite+ variants. It has about 1300 m/s and 1500 m/s of delta-v respectively. It's for LEO missions.

Here's the orbit stage(s) of the Medium and Medium+ variants. It has about 2500 m/s and 2800 m/s of delta-v respectively. This allows it to do SLS-style Munar missions.

And here's the Heavy and Heavy+ orbital stages, with about 4300 m/s and 4500 m/s of delta-v respectively. It's designed for interplanetary missions.

Edited April 21, 2013 by Giggleplex777

[Temstar]

What the, that's a lot of cool stuff you have crammed inside that capsule, I'm afraid I might have to steal that idea.

I take it the capsule's engines are Rockomax 24-77?

[Giggleplex777]

Yes, they are. The only problems are that it reduces the total delta-v of the rocket and is not powerful enough to land by itself (unless you add more engines and fuel), but comfort over performance.

[Tada]

So I´ve tried Olympus II for supply run to my Laythe colonony.

I´ve docked 2 Olympus II silos and used Zeus to push it - after I spend fuel in first Olympus (almost 90% of my Jool burn was complete) I ditched that one and countinued. I was abble to brought full orange tank of fuel onto 80km equatorial orbit of Laythe.

And yeah, by the way I used 2 docking ports on those radial tanks to bring along 2 SSTO space shuttles along. So not even I have a lot of fuel on Laythe orbit, I also have brought 2 new ships.

Next launch I took 2 Shade MKII fighters and 2 of my own JSIF Ion Fighters along for a ride, and also managed to get Laythe orbit with fuel to spare. I find Olympus system very versatile, it is not only a fuel depot, it can easily act as a space tug.

I find it more practical in role of bringing those 2 SSTOs there, because I´ve already designed my JSIF fighter with Jool drive stage - so getting solely those ships there requeries less launches (Olympus II, Zeus and then another Olympus as fuel tank and idealy another one to top all of before start).

Next misson will be to Tylo - my battle cruiser is kinda stranded without fuel, running on vapors, I have to refuel and get back to Laythe. I´m thinking about taking 2 Tylo Landers up there when I´m on my way - It takes like 17minutes burn to get Jool intercept with those 2 heavy Olympus silos and Zeus drivestage. But that qudruple docking system is great, easy to dock all four and so strong it can withstand fierce aerobraking.

[Sunsparc]

I have to say, this is one of the best engineered crafts I've seen. I just put all of this into orbit easily. Zeus was a little bit difficult to work with but nothing unmanageable.

[NOTBUSYENOUGH]

The strong docking port you have set up looks like it would be really effective. I may have to use a design like that on my upcoming mission to Duna. Also you craft looks like it could be a real spacecraft. All the struts you have between your modules make the craft look rickety and industrial (in a good way). Nice Ascent stage setup as well!

[Yatesey14]

maybe im being stupid but im having trouble getting this into orbit, any chance on a run through of how to?

[Giggleplex777]

maybe im being stupid but im having trouble getting this into orbit, any chance on a run through of how to?

How are you doing your gravity turn?

[MaddPhish]

Love this stuff. Tried the heavy docking port, but I can only ever get one or two ports to lock together, leaving rockets still floppy. A good idea for stock strengthening, but for me Quantum Struts are the solution I turned to. I'd also built something similar to Zeus, but with only six NTR's. I just stick a truss and a decoupler where the center engine goes.

[Tada]

Hm.. Thats strange - I always get at least 3 docked

[ViperZeroOne]

Really like your docking port design. Just implemented it on a fairly unstable launch vehicle and it's taken down the wobble considerably. Kudos!