Ironman - not quite yet another lunar lander...

[Raindropz]

Good morning, fellow orbinauts,

I am proud to announce a new sort of vehicle may soon become a regular at some of your lunar operations . More precisely, a reusable transport is on the drawing board that can carry 15-20 tons of payload on round-trips between lunar orbit and moonbases, or haul 30-35 tons of one-way payload and return empty.

So what's special when there are already formidable vehicles available at OrbitHangar that can perform similiar tasks (and are of higher mesh quality)?

The Ironman-type lunar logistics vehicle is assumed to be a vehicle of choice for early or low-budget lunar facilities (your choice ) in that it's designed as a simple & rugged platform compatible with various payload modules. Most notably, its single main engine runs on liquid oxygen and iron pre-mixed into a monopropellant, probably the cheapest and most accessible propellant option available on the moon.

Here's a quick & dirty first screenshot showing an Ironman with a simple unpressurized 20-ton cargo pod. A liquid oxygen tanker variant and a pressurized cabin module will also be available by default.



Ironman with its default payloads will be spacecraft3-based, though a Velcro variant for easier payload customization is considered.

I'm not yet sure whether to code the vessel with a classic hover engine or make it a tailsitter relying on a main engine. Most other landers seem to go with the hover engine variant for easier precision landings, though a tailsitter configuration arguably makes orbital maneuvring a lot more convenient. What would people prefer around here?

I'll keep you updated, especially with a few more screenies.

 

[Donamy]

Cool idea, but one critique would be, that the RCS should be attached to the vessel where they could get fuel, also may want to beef up the landing legs, but it's your ship.

 

[Zatnikitelman]

If you're going the dll route, then why not code it so the main engine is the same as the hover engine? The LSAM with the CEV-E addon works this way and I love it!

 

[Andy44]

Sounds neat, but if you mix iron and LOX, won't you just get slushy....rust?

Perhaps you could make it a hybrid rocket: Cake the iron into solid fuel propellant grain cartridges with some sort of glue binder and feed it LOX from a pressurized tank. What kind of Isp does a FerroLOX rocket get, anyway?


-----Posted Added-----


Here's a disussion about extracting and using aluminum or iron from lunar soil to make rocket fuel.

http://forum.nasaspaceflight.com/index.php?topic=14380.0

It seems like aluminum may have more energy but is harder to extract, if I am following that thread right.

 

[tgep]

That design reminds me a lot of the early Apollo project sketches before Grumman got the contract to build the LEM. I love the reto look but beefier landing legs might be a good idea for a cargo transport.

 

[Andy44]

Cool idea, but one critique would be, that the RCS should be attached to the vessel where they could get fuel, also may want to beef up the landing legs, but it's your ship.

You can run fuel lines through the landing gear structure, and placing the RCS farther from the center of mass makes them more efficient by giving the thrusters bigger lever arms.

 

[Raindropz]

You can run fuel lines through the landing gear structure, and placing the RCS farther from the center of mass makes them more efficient by giving the thrusters bigger lever arms.

Those were pretty much my thoughts, though I agree the legs look a bit fragile given they are supposed to hold fuel lines, wiring and still provide lots of structural strength. I beefed them up and spread them a bit further out.

The RCS position isn't yet cast into stone either. I like the idea of those off-centre RCS pods, but as I understand it, spacecraft3 won't be able to simulate the according effects in a realistic manner. Still thinking about whether I can live with that or not .

Here's a disussion about extracting and using aluminum or iron from lunar soil to make rocket fuel.

http://forum.nasaspaceflight.com/ind...?topic=14380.0

The discussion also has a link to this paper, which I based some of my assumptions on: http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930008606_1993008606.pdf

They briefly studied an Fe/LOX monopropellant for lunar applications, but dropped it from the more detailed part due to the low specific impulse compared to other metals. Around 180 seconds isn't a whole lot of isp, but the idea of a vehicle trading off efficiency and GLOW for cheap fuel caught me. A few first test flights in Orbiter show that we're flying on extremely narrow margins here...


Oh, and two more pics right out the hangar: Two Anim8or renderings showing the latest version, one with the LOX tanker payload and the empty core vehicle:

 

[garyw]

Love it - I am in need of a decent cargo hauler for my moon base. Any chance the legs can be made to fold up against the core vehicle for launch on a delta rocket or similar?

 

[Raindropz]

Love it - I am in need of a decent cargo hauler for my moon base. Any chance the legs can be made to fold up against the core vehicle for launch on a delta rocket or similar?

Not without quite a few changes to the vehicle structure. To be honest, I haven't put a lot of thought into launch options, but an all-up launch on a big rocket or assembly in LEO might be options. We're talking about a dry vehicle mass of around 20 tonnes (plus according payload modules, see below...) and a core cylinder diameter of 6 meters.

Anyway, I like your idea of providing a launch option/scenario with the package. I thought of providing dockable "raw" cfg's for the core cylinder, payload modules and landing legs (maybe packed up some sort of canister) for use with your launcher and assembler of choice... Transition to the fully functional spacecraft3-based vehicle would require re-launching orbiter, but it's an option worth considering.

Now to the next update: There's good and bad news.

- Bad news is I've dropped the Fe/LOX idea after a couple more test flights. They compared just too lousy to my original calculations, and I didn't want to stretch the mass fraction to entirely unrealistic values. I've rather switched to an Aluminium/LOX propellant, providing an isp of 280s and much more robust performance.
I decided to stick to the "Ironman" brand though. I think it reflects the vehicle's multiple roles and ruggedness fairly well...

- Good news is that I'm moving ahead well with the new choice. The basic functionality is pretty much there, but don't expect a full release too soon. There's still a lot of stuff to add & work on. Why not have two more screenies in the meantime:

Ironman-T tanker on a test flight, taking 30 tons of LOX and tank structure to low lunar orbit.

Ironman-C unpressurized barge at Brighton Beach, operating the cargo cradle on the 20-ton module.

 

[AstroCam]

Stylish, once you get the structure sorted out, you could go the whole hog and put ultrahigh textures on it - seeing this with goldfoil LEM style insulation would be pretty awesome. Really look forward to seeing the Ironman completed.

 

[RisingFury]

Wow, this is a nice idea

Though... I don't know about the RCS. The way it's set up now, it can't pitch and can't use translation, can it?

Hopefully I can get to play around with this soon

 

[Woo482]

this would be really good if it was a coded dll with ummu for the passenger module

 

[garyw]

this would be really good if it was a coded dll with ummu for the passenger module

I thought it was just a logistics module? i.e. unmanned.

 

[Woo482]

oh thats just me thinking I read things that I did not I thought he said that there would be a passenger module

 

[RisingFury]

It would still be nice to have a DLL and integrate more features into it over time.

 

[Raindropz]

I'm afraid Ironman (at least a first release) will definitely be spacecraft3-based. It's already pretty much of a learning project, and getting into compiler setup & C++ coding would be overkill for now. Of course, that also means no UMMU, somehwat limited payload support (various modules will come as different spacecraft3 ini's), and limited realism concerning the RCS pods.

Speaking of the RCS, the leg-mounted pods can indeed support any axis of rotation (with marginal translation effects that should be okay to ignore. It's supposed to fire fairly gently and turn like a cow anyway). I'm currently more concerned about linear mode, which would be impossible to achieve in reality, but also impossible to disable in spacecraft3. I'm still thinking of repositioning the entire thing to the main cylinder, Apollo SM-style, sorting out all those issues.

On the pro side, there WILL be a crew cabin / 'dry' cargo variant available, dubbed the Ironman-P. More on that later .

 

[Andy44]

I decided to stick to the "Ironman" brand though. I think it reflects the vehicle's multiple roles and ruggedness fairly well...

Or you could call it the "Aluminum Falcon"....

Speaking of the RCS, the leg-mounted pods can indeed support any axis of rotation (with marginal translation effects that should be okay to ignore. It's supposed to fire fairly gently and turn like a cow anyway). I'm currently more concerned about linear mode, which would be impossible to achieve in reality, but also impossible to disable in spacecraft3. I'm still thinking of repositioning the entire thing to the main cylinder, Apollo SM-style, sorting out all those issues.

One option would be to place the thrusters on a cantilever arm that extends upward from the mounting points of the landing gear. This will add some more mass and complicated plumbing, but it may get closer to the center of mass, and it could even be adjustable to compensate for different payloads and for the burn-off of propellant mass. Just thinkin...

About using sc3, nothing wrong with that. It's my crutch as well. But the nice thing about it is that you can get the addon released earlier and now you have the mesh and texturing done, and have done all the math, so you could always revisit the addon later and re-release it with a custom dll.

 

[Zatnikitelman]

If I may make a slight suggestion for the launch vehicle. Why not make the landing legs extendable? Fold them against the hull for launch, then have them fold upwards into flight position on-orbit. Of course, the backstory could be that it's built on the Moon...

 

[AstroCam]

Hmmmm, i've always lamented scraft3's lack of ummu support as well.
Perhaps if someone could make a generic Invisible ummu vessel?

If you just want people doing EVA from Ironman (No on orbit crew transfers), an invisible UMMU vessel that can hook on to an attachment point/docking port and still has all the features (Airlock open close for example - don't think ejection would be a good idea on this generic vessel) would be a good idea, that way all the scraft3 vessels out there could be given ummu support just by adding an attachment point where they want the airlock.

Could be worth a look at.

 

[tl8]

^ UMMUFA