Project ACES Architecture

[jpv]

Hello,

I am a long time Orbiter fan and forum lurker, figured I'd finally try my hand at some addon making.

The intention of this project is to model the ACES lunar architecture proposed by ULA back in 2009. See the link at the end for the original document that I've used as a reference.

So far I've been working on the first part and the backbone of the architecture, ACES 41. With four RL10 engines and capacity for 41 tons of propellant, it is by itself just a very powerful upper stage for Delta IV and Atlas V. This will be the basic element upon which the fuel depots, crew vehicles and lunar landers will be built.

I've had to use quite a bit of artistic license while modeling since the original is just a concept, but I try to keep it real by referencing existing upper stages and vehicles for the details. Currently it's just the basic mesh with a simple configuration file for testing, eventually I will of course need to write proper modules for staging, propellant transfer etc.

http://www.ulalaunch.com/site/docs/publications/AffordableExplorationArchitecture2009.pdf

 

[jpv]

Started work on the ACES-Orion CEV, essentially the Orion command module with it's service module replaced by an ACES 41 and an ECLSS module.

With more powerful engines and larger fuel capacity, this CEV doesn't need a separate Earth departure stage for the lunar trip after topping off from a LEO propellant depot. The solar panels are replaced by fuel cells burning boiloff hydrogen which would otherwise be lost. Life support and other spacecraft functions are provided by the ECLSS module.

 

[Star Voyager]

Awesome! As a big fan of ULA myself, I'm totally interested in this project. Great work on the spacecraft, too :tiphat:!

 

[2552]

I've wanted to fly an addon like this for a while, thanks!

Some more links with info:
http://www.ulalaunch.com/docs/publications/TheAdvancedCryogenicEvolvedStageACES2006LeBar7454.pdf

DTAL lander:
http://www.ulalaunch.com/docs/publications/DualThrustAxisLander%28DTAL%292009.pdf

NSF Article:
http://www.nasaspaceflight.com/2009...ng-solution-via-eelv-exploration-master-plan/

 

[jpv]

Here is probably the most important part of the architecture, the ACES propellant depot. It is made up of an ACES 41 module joined with an elongated ACES 71 module, for a total capacity of 121 tons of LOX and LH2. Between them is the depot module with solar panels providing power both to the depot and any docked spacecraft. Finally, the larger LH2 tank is shielded from excess heating by a sunshade.

The documented architecture requires at least two depots, one in LEO and second one at the L2 point, with spacecraft refueling at both stops on the lunar trip. Filling the depots takes of course multiple launches either with the dedicated ACES 71 tanker or some other commercial spacecraft.

The second pic shows the Orion topping off at the LEO depot. The models are still missing plenty of detail, miscellaneous equipment, most notably the docking interfaces, but this shows the concept of operation. Another spacecraft can be docked on the other side of the depot. Perhaps even two more on the other axis, the documentation is a bit vague on the docking systems.

 

[jpv]

Finally, here we have the ACES-Altair Dual Thrust Axis Lander (DTAL). Again built on the ACES 41 module, it comes in both cargo and crew versions. Initial deorbit burn is performed with the RL10 engines, after which the vehicle transitions to hover flight for landing.

Here is the crew lander, with Space Ship One style windows for good visibility. The front section is the ascent stage with 6 thrusters on both sides and enough propellant for the return to orbit. Behind that is the integrated cargo section and the ACES module. The empty tanks left behind can be used for storing consumables on the lunar base, and possibly even outfitted as wet workshops for additional habitable volume. The landers have wheels so they should be easy to move around the base. A dedicated tractor rover would be cool, I wonder if that is possible to implement in Orbiter?

The major parts of the architecture are now ready to fly, although the models still need plenty of detail. Next I'll need to start working on the dll's to enable propellant transfer, animations etc. Also need to figure out a way to launch these guys to orbit so we can actually fly the missions.

 

[2552]

Have you tried using the [ame="http://www.orbithangar.com/searchid.php?ID=3462"]Velcro EELV[/ame]'s Atlas V and Delta IV to launch these? Also, any idea when the first alpha/beta will be released?

 

[Wonderer]

Welcome to the forum!

Can't wait for this addon,keep up the good work :thumbup:

HAve you thought about implementing UMMU and UCGO to these vehicles?

 

[2552]

The major parts of the architecture are now ready to fly, although the models still need plenty of detail. Next I'll need to start working on the dll's to enable propellant transfer, animations etc. Also need to figure out a way to launch these guys to orbit so we can actually fly the missions.

Still need plenty of detail? They already look just like the images in the ULA PDFs!

 

[jpv]

Thanks! Velcro seems indeed the simplest solution for now, I'm hoping to eventually write custom launchers for them, but that'll likely be a while. UMMU and UCGO, surely not a problem if they're not too complex to add in.


The vehicles are currently just cfg based, so they're not really useful for anything other than examining the models in Orbiter. I'll want to get at least basic dll versions with staging and animations before releasing. Also, propellant transfer is a rather important part of the system, need to figure that out to make the vehicles work as intended.

 

[francisdrake]

Excellent project! With a 'heavy' launcher delayed to a distant future, the ACES upper stage, together with fuel depots, may provide a usefull way to move heavier payloads out of LEO.

I suggest the basic ACES stage should have a simple docking port at its front, so it can be used an earth departure stage for any vessel.

 

[jpv]

I suggest the basic ACES stage should have a simple docking port at its front, so it can be used an earth departure stage for any vessel.

Yes, that is reasonable, and I suppose one could add attachment points to the rear of the stage too, so they could be stacked together as a heavy-duty departure stage, for interplanetary missions etc.

 

[jpv]

Still need plenty of detail? They already look just like the images in the ULA PDFs!

So far yeah, but I'm hoping to improve on that. Here's the sort of detail I'm trying, just so the models don't look so sterile and boring.

On a related note, rocket engines really are complicated machines. :blink:

 

[Urwumpe]

On a related note, rocket engines really are complicated machines. :blink:

Yes, but you do already a good job with them. Those are RL-10 engines right?

Those have some very distinct ducts on them, but the powerhead is much more compact than on other engines:

 

[jpv]

Setting up the Orbiter SDK in VC++ turned out to be very straightforward thanks to the great instructions here, so much fun learning and trying out the stuff you can do with it.

Here's the ACES depot (artistically not-quite-at-EML2 ) with Altair taking on fuel for a lunar excursion. Wonder what would be a reasonable transfer rate, anyone got some numbers for the Progress/ISS prop transfer rate for example?

Still need to figure out the launch vehicle and staging for the Orion and Altair, then I think we're just about ready to launch the first mission.

 

[2552]

Will this addon simulate propellant boiloff and/or separate LH2 and LO2 tanks? One thing the ACES depot does is store LH2 in the sunshielded ACES-71's LH2 tank, then move the LO2 from the docked ACES-41's LO2 tank to it's LH2 tank, so that all the LH2 is under the sunshield, minimizing boiloff.

 

[jpv]

I wasn't planning on simulating O2 and H2 separately since Orbiter doesn't really do that either, so it will likely just be a single propellant.

Boiloff however is probably the most important issue in the architecture, so some loss propellant over time will need to be modeled. Like with the cryogenic propellant transfer rates, I imagine getting any hard numbers for this will be difficult. Probably just have to guesstimate some reasonable number, maybe with a user-adjustable variable?

 

[Tacolev]

Not unrelated:

How do you plan to deal with station-keeping at the Lagrange point? There is that MFD that will zap things into place but some sort of custom autopilot might let you kill two birds with one stone as far as the simulation goes.

 

[jpv]

How do you plan to deal with station-keeping at the Lagrange point? There is that MFD that will zap things into place but some sort of custom autopilot might let you kill two birds with one stone as far as the simulation goes.

Yes, I was thinking of writing a really simple autopilot that would just calculate the location of the L2 point and do stationkeeping with thruster firings every now and then. Not very elegant but I'm hoping it'll keep the depot in the general vicinity of L2. I think actually navigating there will be the bigger problem, never done a mission like that in Orbiter, so no idea what kind of trajectory is required or if that's even feasible.

Backup plan would be placing the second depot in a high lunar orbit, would result in some loss of performance and mission limitations, but at least it's a more familiar scenario.

 

[Fixerger]

Fantastic screenshots