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smoothvirus
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« on: March 30, 2006, 11:53:10 PM »

Since we've got about three of these things going, I think it's best to consolidate this into one thread. I'll start at the beginning, with the ERV Prototype C.
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smoothvirus
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« Reply #1 on: March 31, 2006, 12:04:31 AM »

This is ERV Prototype "C"


Apologies for the crude sketch, but I think it's enough to get started on. It's very loosely based on the Mars Society Chart from here:

http://www.marssociety.org/images/direct/marsd6.gif

and it's drawn to around the same scale. As I said it's a little crude and some of the dimensions are probably a little off  - the top of the Command Module is a little wonky and I noticed that she's landed on a bit of a slope! Oh well, not much perfectly level ground on Mars anyhow.

I've lifted ideas for Prototype "C" from several sources - but mostly from the Kepler Prize entries and also from the original Mars Direct paper.

Specifications:

- Propellant: Methane/Oxygen CH4/O2
- Power: Solar 2 folding panels stowed in Stage 2
- ECLSS: Closed or Semi-Closed
- Engines:
  Stage 1 6 x 35,000lbs thrust engines
  Stage 2 1 x 35,000lbs thrust engine
  RD-185 Class (As Terry has pointed out we can pretty much use these off the shelf!)
  http://www.astronautix.com/engines/rd185.htm

Concepts:


1) Allow the ERV to be used as a backup habitat while on Mars. I decided not to go with an inflatable mission module since you can't use an inflatable one until you're in Mars orbit. If there's a serious failure on the Hab then the crew can move over to the ERV and spend the rest of the mission there.

2) The Command Module can be used as a radiation shelter for those pesky solar flares. The central support tunnel inside the Mission Module can also serve this purpose.

3) Abort-to-Mars fallback option. We can mount two or three small solid rockets to the Command Module (not shown in my sketch). This would allow a last-ditch abort to Mars surface if there's a failure when the crew launches from Mars to Earth. Mission Control could drive the pressurized rover to rescue the crew via remote control from Earth if this happens. It isn't a very desirable abort option but it's better than "it works or we're dead."

4) Central Support Tunnel - the structure of the Mission Module is made of a lightweight hydrogen-rich composite. The outside hull of the Mission Module is not strong enough to hold the Command Module up all by itself. Most of the load is taken by a central support tunnel inside the Mission Module.

5) Landing gear and cargo bay left on Mars. At Mars liftoff we are only taking the core section of Stage 1 with us. The landing gear and cargo bays stay on Mars, to save dead weight. I have included a photo from a Mars Ascent Vehicle that uses this same concept because you can't see this in my current sketch.

6) As you can see the landing gear is a similar design to the landing gear on Ken's Hab. The ERV would also use the same type of folding heatsheild as the Hab.

Prototype C has four sections:

Command Module: This is an Apollo derived re-entry capsule that seats four. There is a hatch at the back for access to the Mission Module. Upon Earth return the Command Module does a standard Apollo-style reentry. The Command Module is equipped with a parasail and landing bags so it can touchdown on land. I've included photos of a Apollo derived capsule doing a landing at KSC - the ERV command module will land in the same fashion but I prefer Edwards Dry Lake as the landing site. I also included a photo from Boeing's OSP concept to show what a "modernized" Apollo capsule would look like.

Mission Module: Constructed from a lightweight composite around a central support tunnel that holds up the Command Module. Two decks. Not as comfy as the Hab module but good enough to get the crew back to Earth. There's a small crane (basically a block & tackle with an electric winch) that's used to lift samples up to the Mission Module as well a safety line for astronauts coming up.

Stage 2: I made this a little larger than stage 2 as seen in the Mars Society chart, since it's also serving as a service module. Not shown in this drawing (they're stowed) are 2 folding solar panels that provide electrical power for the trip home.

Stage 1: Includes a central core with the 6 engines and fuel tanks. The landing gear and cargo bays are around the central core. At liftoff they seperate from the central core and are left on the Martian surface. There are 4 Cargo bays which store the propellant production plant, Robotic Truck, SP-100 reactor, and the last bay has a fueling station for the rover and allows maintenance access.

Some Small Changes From My Sketch, And Other Ideas:

1) The landing legs may be a little short. I wasn't sure of the size of the engines on Stage 1. We'll need to strike a balance between giving the engines adequate clearance while providing enough room for the Robotic Truck to get down and retrieve the SP-100 reactor.

2) That hatch on the Mission Module should probably be a little lower down.

3) I threw in a capture from the Mars Underground trailer so you'll have a better idea of the "look & feel". Their ERV does look nearly identical to our ERV Prototype "A" (Argonaut) - so Protoype C does look different from Stage 2 up. However, the way they both arrive on Mars is the same.

4) Prototype "C" stands about 82 feet high! That hatch on the Mission Module is pretty high up. If there's a way to squeeze a "service tunnel" from the maintenance access in the Stage 1 cargo bay up to the base of the central support tunnel in the Mission Module we should do it.
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smoothvirus
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« Reply #2 on: March 31, 2006, 12:14:04 AM »

























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smoothvirus
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« Reply #3 on: March 31, 2006, 12:14:50 AM »

Because this whole program is so big and has so many different components, the ERV model will need to be slightly flexable to accomidate the expansion of the program and it's many possible functions.

So let me start by detailing the base.

As you can see there are 5 engines. All 5 engines need to have gimbal meshes, so they need to be kept as seperate objects for animation. Each of the gimbal mechanism meshes also need to be seperate objects also for the animation.

Moving up, the legs need to look mechanical. I've given a good concept to follow, but they need to fold upward and inward. So the parts that are joints will need to be seperate objects to allow for animation of those objects in the folding process.

Between the legs are bays as you can see in the engineering drawings.
One bay holds the SP100 reactor. That will need to have a deployment mechanism which has not yet been designed. The deployment mechanism will need to function with the mars truck which will be contained folded up in another bay. The Mars truck and its associated deployment systems and possibly a ramp.

I have a basic drawing for the Mars truck, but it could need some review.
There is another bay that will contain a truck modification pallate. This will also need a simple deployment access system so the crew can get it easily when the Hab arrives.

There will be storage for a back-hoe robot arm. And other tools.

The SP100 bay will also have a spool of cable that will need to be animated of sorts. And there are some problems with that, but not completely unsolvable.

The red 1st stage will seperate from the legs and bays for Earth departure at the end of the mission. So that will be a seperate object as well, again those engines need to gimbal, and we will need to see engine components like the mixing chambers and some plumbing.

After seperation, of the lower stage, some seperation rockets will fire prior to the Upper stage air-start. That engine will also gimbal, and again we need to see plumbing and mixing chambers.

You will see in the schematic there are lots of tanks in that upper stage, so might also be appropriate to show them from the bottom nestled inside the outer shroud.

In the drawings I have the RCS - Reaction Control System pods attached to the lower section, they will actually need to be part of the very bottom section of the lower stage. This will help keep the entire craft under control during the cruse back to Earth.

This upper stage actually comes in two segments. One segment (the part with the engines and tanks) is called the Service Module, it has all the consumables and fuel, solar panels, radiators, life support, to keep the crew alive for the entire 6 months return voyage to Earth. Many of the sub-systems are close loop cycle for effecient use of mass. Like the water and air.

Even the fuel will have a close loop repress system.

As you can see from the Engineering digrams, there are side doors on the four corners of this module. 2 opposing doors for Radiators to bleed off extra heat, and 2 opposing doors for solar panels. The RCS pods should be located between these modules to prevent or minimize any accedental damage.

Again animation rules apply to these parts.

The segment above that is called the Mission module. This contains the Crew quarters, labs, gym, restroom, and a RAD shelter plus food stores.

There are two flavors of this stage. One with a docking port on the top, and one with only a sealed access tube. Both provide access to the RAD shelter and the entire Mission module crew space. Either way this central tube runs right down the central access of the Mission module. So any docking port or access system will be at the very top of the Mission Module in the center.

We have two different flavors because the ERV needs to stay extreamly light for our first few missions, after that our mass limits might become more flexable and including a docking port to allow ERV's to have an interconnect could provide additional reusability of the hardware as well system infrastructre both on the surface and in Mars orbit.

Also there is the safety issue of having a hole in the bottom of the CEV's heat shield. It has been suggested that this will work fine. But I also see another issue of possible seal failure, between the interconnect of the CEV's heat shield hole and the RAD shelter tube on the Mission Module.

So because there are two flavors of the CEV, there must also be two flavors of the Mission module that connect to the CEV.

The Mission module also has an optional extendable airlock porch, and a winch and pully system to get the crew up to the inflatable porch.

The inflateable airlock will need to be animated as usual and the winch-pully system, Doors, everything.

In the second flavor of the Mission Module there will be no side airlock just a metal ladder/hand rail going up to the CEV.

We might also want to include a small foot elevator on the outside. That would probably be a better solution.

Now the CEV will come with two flavors.

Flavor 1 will have a hole in the heat shield where it connects to the Mission Module. The crew climbs into this just prior to jetison of the mission module and Earth entry interface.

It will have optional Retro rockets that the crew can attach to the outside in the event of a Mars Ascent abort. These will keep them from slamming into the surface of Mars should they need to abort prior to TEI.

This flavor will jetison the heat shield and probably have a ring of airbags that help cusion on landing.

Flavor 2 will have a docking port in the nose but no hole in the heat shield. just like the Lockheed Martin/Northrop Grumman proposal.

This particular flavor will also have the option of an escape tower on top with a crane adapter that can be taken off (crane) prior to Mars departure.

The escape tower will also need to be a seperate object, as will the crane attachment. Both the escape tower and the crane attachment will be installed by the crew upon their arrival to allow them to perform heavy lifting or rover/truck maintance.

Lets not forget the Virtual Cockpit for the Mission module, the CEV and Mars truck. So there is some modeling inside these vehicals as well. Of course anything that can't be seen inside or out after all the doors are open doesn't need to be modeled. But all the interior bays and equipment, plumbing, everything that can be seen behind open doors.

That means some interior modeling and texture work as well. We will want to keep the polys low so it will have to be rudimentary with textures supplanting most of the 3d objects. Obviously we can't be modeling the threads on the spokes of the bicycle in the gym. Or the circuit boards for the computer lab. But greater detail will need to be added to certain parts of the CEV and the Mission Module. Such as life support, Climate controls, Human factors.

Someone will need to design the panels, and model the controls for the cockpit around the Pilots MFD's and Commanders MFD's

Maybe if you guys are up to it, even include a VC for the mission specialist or flight engineer, navigation, ect... Just a few thoughts to help insipire you to get the ball rolling.

Make sure you study the diagrams and engineering drawings carefully! The quality of these models needs to be nearly perfect! and still reasonably low on the poly count for medium to low end computers. But not too low! it does need to lood VERY nice! and ULTRA realistic!

Texture maps will also need to be done to very high quality! More on that later, still lots of development to do in that department.

Everything needs to look functional and realistic according to current technology. Anything that moves needs to be a seperate object so the programmers can program it to animate in the simulator.

Let me know if you need any additional clarrification or further details on functional design or system operational parameters. I've been leading this project, but I don't have the time to do all the modeling my self, so I think this well be a good arrangement.

EDIT: I forgot to mention, there is also a heat shield that will sit below the Landing legs when they are folded up. This will protect the entire ERV from the hot gasses as it aerobrakes into the upper atmosphere of Mars after arriving from Earth, but prior to landing at the designated landing zone. After Aerobrake this Aeroshield will drop away and a set of droge chutes will slow the rest of the ERV to supersonic speed, then the mains will open and slow it to subsonic speeds. Once it drops to an acceptable altitude the chutes will drop away and the main engines will light up, tactial ground radar will come to life, and direct the ERV to a safe landing.
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aftercolumbia
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« Reply #4 on: April 07, 2006, 03:56:06 PM »

I feel like slapping bheick's current Descent Module mesh on top of this thing just to see what it would look like...I think it would look terrific.
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aftercolumbia
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« Reply #5 on: April 10, 2006, 09:04:34 PM »

Based on calculations from AFAL, the best case reasonable engine for a Mars ISPP oxymethane engine gives a specific impulse of 362 seconds.  This was calculated from the AFAL specific impulse calculator from www.dunnspace.com using the following parameters:

- Phase equilibrium shifting terminated ("frozen") at the throat
- 1451psia (10MPa) chamber pressure (consistent with a typical turbopump fed engine with a somewhat higher than usual operating pressures)
- no margin was taken out for flow losses (most gas cycle engines are about ~5% below AFAL numbers.  Expander and staged combustion lose about 2%.  Oxyhydrogen engines, interestingly enough, don't seem to suffer this loss, probably because oxyhydrogen engine use LH2 as a nozzle coolant and thus recover most of the heat lost to flow inefficiencies this way.)
- 1psia (6.892kPa) exit pressure, typical for a vacuum optimized engine.

The Case assumes 380sec.
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smoothvirus
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« Reply #6 on: June 22, 2006, 08:11:11 PM »

Seth is modeling the ERV now, here's the service module:

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smoothvirus
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« Reply #7 on: June 22, 2006, 08:12:17 PM »

Mission Module

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Iceversaka
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« Reply #8 on: June 22, 2006, 08:12:26 PM »

Hey guys, just thought you'd like to see a nice shiny pic of the Service module as it is nearly done.



Seth
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smoothvirus
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« Reply #9 on: June 22, 2006, 08:39:46 PM »

Service module with radiators and solar panels deployed

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Zachstar
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« Reply #10 on: June 22, 2006, 10:04:44 PM »

Very Nice work!!!!

And with Pricci now programming it! Very good!
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« Reply #11 on: June 23, 2006, 02:46:37 PM »

Hey guys, zachstar just let me know about this fourm and I'm very impressed, everything looks great. The ERV looks amazing and  I can see that a lot of design work went into it. Its come along way, since the crappy model I made.
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smoothvirus
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« Reply #12 on: June 23, 2006, 07:18:17 PM »

Quote
Hey guys, zachstar just let me know about this fourm and I'm very impressed, everything looks great. The ERV looks amazing and I can see that a lot of design work went into it. Its come along way, since the crappy model I made.


Good to see you back, we're actually using that model you made as the "Dummy ERV". It's basically a static object that doesn't do anything but you can land the Hab next to it.
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Iceversaka
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« Reply #13 on: June 24, 2006, 09:42:44 AM »

Quote
Hey guys, zachstar just let me know about this fourm and I'm very impressed, everything looks great. The ERV looks amazing and I can see that a lot of design work went into it. Its come along way, since the crappy model I made.

Good to see you back, we're actually using that model you made as the "Dummy ERV". It's basically a static object that doesn't do anything but you can land the Hab next to it.

I thought I did that dummy model...?

Oh right, the old dummy model, not the new one....hehehe

Seth
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aftercolumbia
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« Reply #14 on: July 08, 2006, 11:51:08 PM »

The latest pics are busted on my system Sad
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