Flight Question Mars Transfer Vehicle.

[Astro SG Wise]

So, I understand that many of you are familiar with the CTV Pheonix mission pack on Pappy's Hangar. The pheonix lander, also known as the Lunar Transfer Vehicle. It has a good design and structure, but I have been thinking about alternative uses for it. I am very much interested in Mars mission stack designs, and I have been trying to come up with different concept designs, including the use of the SLS and the Orion MPCV. I was trying to make a design, or find one, of a Mars lander that was small enough to take with one single stack. I saw the LTV, and instantly, I thought it would be a great advocate. There are a few things that had to be adressed first , and still that mujst be adressed in the future...

It's a Lunar lander. Obviously, NASA's Eagle lander couldn't actually land on mars. Was the LTV the same way? The only way to find out is if it landed. I tried and tried, and tried again, and finally had a controlled decent with the LTV, and enough fuel to get back into orbit. Phew! :thumbup:

Does it have a realistic fuel level? This is one other problem: it seems like LTV may just have to much fuel to be realistic. If this is the case, the lander, or the concept design, must be changed. I am not sure how much it's mass and size can actually take, but I hope it is realistic enough. If anyone else knows how to compute for that, that would be a great help.

Either way, it's design and structure make it a great advocate for a mission to Mars. It even has some cool similarities between the Orion MPCV. Look alikes make it that much cooler!

So, my main concern is that LTV would be realistic enough. If so, it does well with a stack, crew space, and flight capabilities. If anyone else has any good ideas for a Mars mission, stack, lander, or other aspects, that would be great.

Some more pics of the LTV (which I dubbed the MTV).

Cheers!

 

[francisdrake]

It is an interesting idea to use the LTV as a Mars lander. The LTV is a very detailed and powerful vessel. A quick assessment indicates an empty mass of 3.7 ton (?) and a fuel mass of 18 ton. It is indeed a little overpowered as a lunar lander, but I am not sure if it could land and then ascend back to Mars orbit, being a single stage vessel. Did you try that?

For a Mars landing an aeroshell (heatshield) would probably be necessary to protect the lander in the first phase of the atmospheric entry.

A Mars ship could consist of the (encapsulated) lander, an Orion, an ISS-type living module, a drive bus and its fuel. The bus could be near-tech, for example with Methan / Oxygen engines. Or it could be a little further in the future using a combined chemical / solar electric propulsion.

 

[Michael_Chr]

How about making an aeroshell so you could gain some dV for the descent by using atmospheric braking. I also played around with the LTV once. Agree with you that it was way to overpowered. So I did some calculations. Since I was doing this for lunar lander I planned to use N2O4 and Aerozine50 (ISP:321 sec). Also I "borrowed" a small ascent vehicle sitting on top of the LTV...no point in sending the entire vehicle back...you just needed the crew backed I resorted to.
Since you plan to go to Mars you would most likely also use N2O4 as oxidizer and some sort of hydrazine based fuel. LOX LH2 has a higher ISP but the boil-off for the LH2 would make it less attractive for such a long mission duration.
So here is the deal. Based on the following figures you get a realistic dV of 1051 m/s:
Lander vehicle empty mass: 12900 kg
Ascent vehicle mass:8353 kg
Lander vehicle internal tank volume: 7.179 CuMtrs
Lander Vehicle Propellant Mass: 8,631 Metric Tons.

Using the mesh file from the LTV I realized that there wasnt enough internal volume in the LTV. In order for that to work and have enough crew space I "streched" the mesh file by 1/3 so the vehicle became higher and I also created an SC3 vessel for that based on the data above.

Now...a dV of 1051 m/s is not enough to make a lunar descent and landing. So in order to have enough fuel I added 4 Velcro based external propellant tanks that was jettisoned when depleted.
Single Ext tank volume: 4,147 CuMtrs
Single Ext tank empty mass: 0,275 Metric Tons
Total Ext tank propellant mass: 19,944 Metric Tons.

This provides for a total mass prior to descent burn initiation of 50,928 Metric Tons and will give you a dV of 2539 m/s which is close to the Apollo figures.

I have uploaded some pics of how it looked when it was finished. Not so aesthetically pleasing as the original but never the less realistic.
http://www.orbiter-forum.com/gallery/showgallery.php?cat=690&ppuser=

So using the SLS from Gattispilot you should be OK concerning launchmass and launch fairing diameter. However you are approx 1600 m/s short in d/V for a Mars landing. So either an aeroshell or additional braking stage has to go along.

I stopped this project some time a go and started to work on a more enhanced lunar lander.

If you are planning to integrate a Mars program with the SLS I would like to hear more about it since I'm working with Gattispilot on the manual and putting a package together for the SLS for upload. It could be included in the package. Of course Gattispilot has the final say on it...but I think he would be open to the idea.

 

[Astro SG Wise]

Thanks to both of you! To answer francisdrake's question, yes, I was able to get it to land, and take off into orbit again yesterday. The only problem, as mentioned, is that the LTV does not have a realistic fuel weight. The reason I really liked the LTV for a mars mission is that it had similar (cool) features as Orion, and didn't have to look ugly, like Pegasus Ares. I wonder what would happen if I added the heat-sheild from the BM-lander, and put it on the landing legs of the LTV. That might work out great. Hey, Michael, could you give me that Lynx lander? That would be great.

---------- Post added at 06:58 PM ---------- Previous post was at 06:21 PM ----------

Oops! When attempting the re-entry, I ended up smashing into mars. How does one land with an aero-brake type lander? :lol:

 

[Michael_Chr]

I will dig into my old projects and see if I can get a version of the Lynx up and running. I was at that considering using the new generic vessel project from Face and Artlav as the basis instead of SC3. It has native UMMU support...could come in handy for this type of vessel. By the way...Astro... What vessels are present in the upper most pic in your post above.

 

[Astro SG Wise]

I believe that you are referring to gattispilot's ATHLETE, with the BM-Lander. I understand that you were much involved in that project. I also posted that picture on the TRIATHLETE thread.

 

[orbitingpluto]

To answer your question, my guess is you'll have to ditch the shield rather early in the descent because there is only so much atmosphere to scrub off velocity with. I don't have any recent experience landing at Mars, so the best I can advise here is to practice, and perhaps research the descent phases of the various Mars landers(MSL Curiosity, the twin MER rovers, the twin Viking landers, there's been at least a dozen) to see what numbers would sense for your situation.

Now, I know you have an lander in mind(the LTV) and a earth return vehicle(Orion), but I feel it's wise to to point out some addons you can use as intended or just borrow pieces to incorporate into your own thing.

Mars DRM 1(thread link)- Still WIP, but there's a few releases to play around with, [ame="http://www.orbithangar.com/searchid.php?ID=6680"]this one[/ame] being the most recent. Definitely something to watch, as it's aims to be a complete Mars mission package.

andymc's Crew Transfer Vehicles and Cargo Transfer Vehicle-Three part package, consisting of the[ame="http://orbithangar.com/searchid.php?ID=2713"] base for the Crew version[/ame], [ame="http://orbithangar.com/searchid.php?ID=2789"]the update[/ame], and [ame="http://orbithangar.com/searchid.php?ID=2794"]the Cargo version[/ame]. I haven't fooled around with these in a while(if ever, my memory is a bit poor right now), so I'll have to do some testing before I say anything.

[ame="http://orbithangar.com/searchid.php?ID=3248"]Mars For Less[/ame]- The, "for less" part refers to the addon's focus on showing how a Mars mission could be put together using LVs in the neighborhood of 25mt instead of 100+mt LVs. The one thing to keep in mind that TMI is tough in this addon, because you have a bunch of stages to wrangle, in part because one big stage to do the TMI wasn't a possibility. You don't have to worry about this if you choose to get a TMI stage from another addon and use that, along with a larger class of LVs to launch it.

francisdrake's MEM- Mentioned in one of the readme files for andymc's CTVs, I found a working link, since the one in the readme is out of date. From the readme, it's ascent vehicle is based off an Orion-CEV, so that is interesting, but I don't know much more than that. I'm a a bit pressed for time, so I haven't tested it yet.

I was planning to leave links to references and studies that would help you plan a Mars mission, but hopefully I can do that later.

 

[IronRain]

francisdrake's MEM- Mentioned in one of the readme files for andymc's CTVs, I found a working link, since the one in the readme is out of date. From the readme, it's ascent vehicle is based off an Orion-CEV, so that is interesting, but I don't know much more than that. I'm a a bit pressed for time, so I haven't tested it yet.

I was planning to leave links to references and studies that would help you plan a Mars mission, but hopefully I can do that later.

Link gives me a 404

 

[orbitingpluto]

Thanks for the heads-up that the link isn't working, should be fine now. Since I'm posting, here's the document that inspired the Crew transfer vehicles(link supplied in the pdf doesn't work anymore). I should really get to bed soon.:goodnight:

 

[Astro SG Wise]

Thank you for the links. My original goal was to make a realistic stack design that uses NASA's future (contrary to Constellation) plans, and cuts down on complexity. If all the cargo was delivered to mars in the first place, then one big stack, with return vehicle, lander, and habitat, would take the crew there and back again. It would make it more simple than having to make other stacks to rendezvous the crew with in orbit. That's why a compact, hi-tech lander was necessary, and I thought the LTV worked pretty well. Thank you for the links, they were very helpful. :tiphat:

---------- Post added at 01:59 PM ---------- Previous post was at 01:50 PM ----------

A Mars ship could consist of the (encapsulated) lander, an Orion, an ISS-type living module, a drive bus and its fuel. The bus could be near-tech, for example with Methan / Oxygen engines. Or it could be a little further in the future using a combined chemical / solar electric propulsion.

I think orbitingpluto can agree with me on this one: Solar Electric Propulsion will most likely be too weak. I agree with having some sort of fuel capacity though. In both of my designs, I use the [ame="http://orbithangar.com/searchid.php?ID=5339"]RNS[/ame] to boost the stack there, and one to boost back. I have also found that Starlab may be a worthy version of a habitat vehicle (requires the SLS to launch).

 

[francisdrake]

Thanks for the link to my old MEM
It is based on NASA concepts from the 1960's. I re-used code from the CEV for the programming. The ascent stage just barely makes it into orbit. Never quite finished that, should have added some drop tanks to it.
---
I would like to break a lance for a concept called "Combined Solar Electric and Storable Chemical Propulsion". It is described here.

Synopsis:
Place the solar-chem vesel at EML-1, so you don't have to spin up from the bottom of Earth's gravity well.
Use a chemical kick-stage to get it moving, then use the solar-powered ion drive during cruise.
Park in a highly elliptical Mars orbit. This allows later to make a chemically powered Oberth-maneuver to escape from Mars for the return trip, using the solar powered drive again during the return cruise.
When back at EML-1: Refuel and repeat as desired.

The advantage of this concept is that it avoids placing a nulear reactor in space. For the forseeable future nuclear power does not seem to be an acceptable option for space vehicles (aside from RTG's). So out to Mars orbit, or even to the asteroid belt, solar power is an alternative. Combining it with chemical thrusters may provide shortened flight times at an acceptable weight penalty.

 

[orbitingpluto]

Thank you for the links.

Your welcome.

My original goal was to make a realistic stack design that uses NASA's future (contrary to Constellation) plans, and cuts down on complexity.

Don't discount addons like the DRM 1 one or other addons based of older planning cycles- they might be from a different time, but they are near-tech and since most are based off of NASA plans, should be able to ft atop a SLS within mass and fairing limits. Cutting down on complexity is way more negotiable, since having a frustrating mission plan could become un-fun to the point of you giving up on it.

If all the cargo was delivered to mars in the first place, then one big stack, with return vehicle, lander, and habitat, would take the crew there and back again. It would make it more simple than having to make other stacks to rendezvous the crew with in orbit. That's why a compact, hi-tech lander was necessary, and I thought the LTV worked pretty well.

There's a horde of options to exercise in carrying out a Mars mission, surface rendezvous being one of them, and caching supplies at convenient moon of Mars being another I can think of off the top of my head. Maybe either of those wouldn't fit with what you want to do, but it's something to think about.

Also, the LTV is rather unrealistic, with it's propellent and mass figures not just out of line from reality, but a lot out of line.

I think orbitingpluto can agree with me on this one: Solar Electric Propulsion will most likely be too weak.

Too slow is what I said, and your right as far as people are concerned. Cargo on the other hand, can weather the longer time in space with far fewer(to perhaps no) ill effects, so solar electric is very much an option for cargo or other things that should be in place at Mars before the people are sent. Or for the regular supply runs after crews start flying back and forth. Solar electric is very efficient, and with all the propellent you do not have to launch from Earth to feed the solar-electric engines, your Earth LVs can move more stuff- leading to you being able to spend that potential mass on equipment, goods, or other things that no longer have to be propellent.

---------

Anyway, while it was molded while Constellation was still a thing, the Mars DRM 5.0 should still serve as reasonable enough reference. Depending on what more you want to know, there's always Google, but there's also Atomic Rockets, and the NASA Technical Reports Server. Atomic Rockets fills the gap between knowing nothing and having a general grasp of spaceflight topics(along with a load of other stuff, all nice) and the NTRS is the clearing house for all sorts of info, most of which is available online as pdfs. I know I said something about studies(more than one), but a few too many unrelated things caught my eye when I was researching.

The guy behind the Mars for Less idea did write a article in the Space Review, and while I know Astro is using the SLS, I can't quite resist the idea of posting a link for future reference. It's in two parts: page1 page2.

--------

Thanks for the link to my old MEM
It is based on NASA concepts from the 1960's. I re-used code from the CEV for the programming. The ascent stage just barely makes it into orbit. Never quite finished that, should have added some drop tanks to it.

Your welcome, and from the one little test I did, it appears to not crash in 2010. If I can manage my time a bit better, I hope to try to land it later tonight and see how that goes. Thank you for making it.:thankyou:

---
I would like to break a lance for a concept called "Combined Solar Electric and Storable Chemical Propulsion". It is described here.

Synopsis:
Place the solar-chem vesel at EML-1, so you don't have to spin up from the bottom of Earth's gravity well.
Use a chemical kick-stage to get it moving, then use the solar-powered ion drive during cruise.
Park in a highly elliptical Mars orbit. This allows later to make a chemically powered Oberth-maneuver to escape from Mars for the return trip, using the solar powered drive again during the return cruise.
When back at EML-1: Refuel and repeat as desired.

Sounds good, though I haven't clue how to do that kind of flight planning(Bit of a note, I haven't actually visited any planets outside of the Moon and Mars in Orbiter, so there are many flight plans I'm uncomfortable with carrying out:shifty. As a plus, reuse too.

Would comment more, but real life calls.

 

[Astro SG Wise]

Thank you for the informational comment! Yes, I understand all of these concepts exist, and I have been trying to work with them for a little while, such as the DRM. Personally, I feel like that would be to many rockets for NASA's future. The department's budget is so low anyway, that 10 Space Launch System launches might be a little bit of an overload. Thank you for all of the suggestions. I am just trying to think of how NASA would do it well with it's new Orion MPCV and SLS.

Yes, orbitingpluto, the LTV is quite unrealistic. I would like not to use the Pegasus Ares, which is a preferred choice among some. I have tried francisdrake's CEV derived MEM vehicle before, but at the time, I thought it would be weird having two Orion-like vehicles on the same stack.

Will comment more later... Busy at the moment...

 

[Astro SG Wise]

I tried the Mars for Less cargo landing vehicle, and found that I could not land it :facepalm:. Oh well.

---------- Post added 01-29-15 at 03:49 AM ---------- Previous post was 01-28-15 at 09:16 PM ----------

So, I have done a little thinking, and came up with this general design using NTR Boosters, Orion MPCV, and a compromise from the Troy Mars Mission concept. It only requires 2 stacks, and 2 rendezvous stages.

The Troy Mars Mission concept is here.

https://www.youtube.com/watch?v=Uj45Au3KCRg

Would the three Troy hab modules suffice for the mission?

 

[orbitingpluto]

I tried the Mars for Less cargo landing vehicle, and found that I could not land it :facepalm:. Oh well.

---------- Post added 01-29-15 at 03:49 AM ---------- Previous post was 01-28-15 at 09:16 PM ----------

So, I have done a little thinking, and came up with this general design using NTR Boosters, Orion MPCV, and a compromise from the Troy Mars Mission concept. It only requires 2 stacks, and 2 rendezvous stages.

The Troy Mars Mission concept is here.

https://www.youtube.com/watch?v=Uj45Au3KCRg

Would the three Troy hab modules suffice for the mission?

]

Quote from the document I found detailing Troy:

In this report Reaction Engines has investigated the role that the SKYLON spaceplane might play in rendering a Mars mission more achievable in terms of logistics and cost. In order to examine the problem a SKYLON compatible Mars mission has been studied in some detail to assess the nature of the payloads and traffic flows involved. The study has been given the working title ‘Project Troy’. However, it is stressed that the heart of the study is to examine the role of SKYLON in such an undertaking, the Mars mission being effectively a by-product of that study.

I haven't found anything relating to the habitats in the document, so I guess it was one of the things they felt was beside the actual point of the study.


In other news, I've gotten around to test flying francisdrake's MEM, at least in landing, and I'm pleased at how well it works. The only problems I've had where mostly pilot-inflicted errors, and the automatic stuff works like a charm.

 

[Astro SG Wise]

Yes, I saw their purpose behind SKYLON. Skylon can only take smaller pieces, while SLS could take bigger and better propulsion stages and hab modules. The stack designs I came up with were a combo of Constellation and Troy, without the Skylon. The good thing is, is the fact that it seems like the three hab modules work. This would be the schedule.

Cargo Stack Operations
1) SLS Launch Chemical Propulsion Booster (CPB)
2) SLS Launch Cargo Delivery Vehicle (CDV)
3) Rendezvous and Dock Cargo Delivery Vehicle to CPB
4) Launch* Mars Transfer Vehicle Lander
5) Rendezvous and Dock MTV with CDV stack
6) Burn Cargo stack to Mars.
7) Correction Burns with CPB
8) Jettison CPB
9) Orbit Insert with CDV Chemical Propulsion.
10) Jettison Base Cargo Modules (BCM)
11) BCM re-entry burn and Landing

Return Booster System
1) SLS Launch RBS
2) Burn for Mars using SLS Second Stage
3) Orbit Insert with RBS

Crew Stack Operations
1) SLS Launch CPB
2) SLS Launch Mars Orbital Habitat Vehicle (MOHV)
3) Rendezvous and Dock MOHV and CPB
4) Launch* Orion MPCV
5) Rendezvous MPCV and Crew Vehicle Stack
6) Burn Crew stack to Mars.
7) Correction Burns with CPB
8) Jettison CPB
9) Orbit Insert with MOHV fuel
10) Crew stack rendezvous with Cargo stack
11) MPCV dock with CDV
12) Crew transfer to MTV lander
13) Undock MTV
14) Re-entry burn and landing
15) Surface Exploration
16) Surface Takeoff
17) Rendezvous and Dock MTV with CDV
18) Crew Transfer to MPCV
19) MPCV dock with MOHV
20) MOHV Rendezvous with RBS
21) Burn for Earth
22) Correction burn with RBS
23) Jettison RBS
24) Crew leave in MPCV
25) MOHV Earth Orbit Insert
26) MPCV Crew Module Re-entry

* Launches of Orion MPCV and MTV may not require Space Launch System

I feel like these ideas are semi-old, because stacks are really the only realistic way to do a Mars mission, but at least it's a start. Now, the problem would be finding out if the lander would work. Maybe a combination of a Mars Direct program and MEM version.

My older design required only one stack.

Then with the RNS...

And the Phobos Version...

Still thinking... :lol:

---------- Post added at 01:57 PM ---------- Previous post was at 01:55 PM ----------

]
I haven't found anything relating to the habitats in the document, so I guess it was one of the things they felt was beside the actual point of the study.
[/FONT]

Watch the video. The point was using SKYLON, but they did include habitat designs as well.

 

[orbitingpluto]

A video isn't much to go on- minus any specific information about the habs themselves, what's in the video could be little more than an artist's idea of what the habitats could look like. I'd suggest seeking out stuff like this paper I found on the NTRS, which is all about doing a lean, fast Mars mission with as much current equipment as possible, like a ISS and MLPM derived habitat modules. You would have to tweak their plan to fit the RNS, but I think that would be far easier than guessing the mass and other stats of the Troy habitats.

 

[Astro SG Wise]

With RNS, not drawn to scale.

 

[Astro SG Wise]

These are some other pics I took today. Includes Orion MPCV, MTV, RNS, and CTV/ATV2 Lunar Booster Stage.

---------- Post added at 05:25 PM ---------- Previous post was at 05:18 PM ----------

Also, here is the cut section. Yellow is living space, and red is fuel. I think that the MOHV would need fuel for orbit insert, because the RNS couldn't get all of this to Mars without the help of the LBS. It is still pretty heavy, despite it's size. The MTV would undock and re-enter Mars first, then the engines would insert the stack.

 

[orbitingpluto]

This really should have been posted after your earlier outline, but I forgot to do it then: Anyway, I know making up acronyms is fun, but it's necessary for your reader's understanding and good humor to show the term itself before shortening it- while things like MPCV and RNS can be assumed to be well known enough to not put it in long-form, that isn't the case for terms you come up with. It's kind of obvious how throwing out acronyms without explanation can confuse someone, with sentences like "the MCaTV puts the stack on a S-EMT, with the spare OHV, MCaL, and MCrL aboard, followed later by the MCrTV with the ERV and prime OHV on a F-EMT" being an example(that I made up just now), but it also frustrating as reader to be left with a mess of acronyms, and with only context to lend some help in figuring out what it all means.


Anyway acronyms aside, I do have a few comments on your chosen stack, in no particular order

• I know you said that you thought using francisdrake's MEM would be a bit weird, but the MEM is better suited for the task(it was built to land and take off from Mars in the first place) and it's not nearly as unrealistic as the LTV. If the weirdness is still too strong to allow use of the MEM, markp's DRM 1 addon has suitably dissimilar landers to borrow. Integrating them in their aeroshells with the rest of your stack would probably throw your 'one stack to Mars' idea right out on the basis of mass alone, though you would gain the ability to land UCGO cargoes on the surface, among other neat things.
• One RNS wasn't intended for pushing a Mars-bound payload all by itself, so three of them can be seen in graphics made to promote the old IPP plan that the RNS was part of. You can see some of these graphics in this article by David Portree over on Wired, and if I had a bit more time I might be able to find out if the linked pdfs at Atomic Rockets exist anymore.

---------- Post added at 07:04 AM ---------- Previous post was at 03:02 AM ----------

Those pdfs on the RNS are likely gone, but I sent a message to the help desk, so sooner or later I'll know for sure if those aren't available from the NTRS anymore. On a different tack, I found this report on the NTRS that while dated, certainly is interesting.