CEV Particulars

[rsp1202]

Can we speculate a bit on CEV layout ,etc.? It's not too early, is it? It's been a whole seven hours since announcement.

1) Does the new proposal lock-in blunt capsule design and rule out biconic? I was just starting to get interested in biconics featured on this site and NASAWatch/SpaceRef, after discarding the lifting body concept. Now that appears to have been cap(sule)-sized also. The early concept work featured a two-deck arrangement for four to six astronauts, with an airlock/mission module behind the biconic capsule/crew compartment, followed by service module. How will blunt capsule be laid out -- single or double-decker -- and will crew have to depressurize the whole capsule to go EVA, like Apollo?

2) Apparently NASA doesn't feel the need for separate mission module for moon missions since it has LM follow-on to act as such. But what of long-duration Earth orbiting missions to ISS, etc., or Mars missions? Are we dealing with Soyuz-style module up front, nose to nose with CEV? Will MM be launched separately to meet up with CEV in orbit, or will CEV/The Stick need fairing to smooth the airflow during launch? Will CEV as proposed be an all-in-one unit without need for extra module?

[SRBseparama]

There's a load of info and specially designed graphics on the CEV part of the forum which are actually EXACTLY like what they decided on. Out friend from Portugal (I think) was spot on.

[simcosmos]

Hello all

Here goes a little more of "talking to the air" (this to say that what I will write next is, as usual, just my impressions on the subject)

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CEV: Capsule VS Biconic
-----------------------------------

From some time now that several hints seemed to suggest that NASA would go to an Apollo shaped capsule design. Both biconics and capsules have their advantages and disadvantages. NASA gave the reasons why they chose the capsule design here:

http://www.nasa.gov/missions/solarsystem/cev_faq.html

To add to those reasons, the capsule seems easier to integrate with other vehicles (even planetary landers… I would not be too much surprised about seeing a CEV capsule on top of an ascent phase, like in many Mars exploration pictures available on Internet, who knows?)

As for the biconics: the main advantages are a smoother g profile (during another planet entry / Earth reentry) and better control for stuff such as crossrange…

Again on my opinion, I think that biconics are the way to go, especially for early Mars exploration (talking here about building early bases)… And even for planets with no atmosphere, the same fuselage could be used (on that case with a lighter heat protection – by the way, these protections also help to control temperature while in space)… But the biconics would be something bigger… something with at least 20m length…


So, summing up:

a) I believe that, regarding NASA situation, one capsule for the CEV is the best way to go regarding safety, affordability and long-term exploration goals. It can be used in many roles and it is “easily” integrated with other space hardware. Accordingly with the latest news, the contractors are free to make design choices except for the overall dimensions and Apollo external shape.


b) Biconic have their advantages (look at the Russians) but perhaps such effort is best suited for things like the ones presented in these links:
http://www.marssociety.org.au/MarsOZ.shtml

http://www.marssociety.org.au/library/MarsOZ_Proposal-ver1b.pdf
http://www.marssociety.org.au/library/MarsOZ_Addendum1.pdf

(from http://www.marssociety.org.au/ )

Also interesting:
http://www.aa.washington.edu/research/ISRU/ARES/ares.htm
http://spot.colorado.edu/~marscase/cfm/cfm84/cfm84plan.html


c) Some more about Biconic VS capsule in this Orbiter Forum post:
http://orbit.m6.net/v2/read.asp?id=26235



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CEV: single / double decker and EVA
---------------------------------------------------------------

As some may already know, I have been working on things like the SRB launcher addon for Orbiter space simulator:
http://orbit.m6.net/v2/read.asp?id=25364
http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=414&start=1

That addon is still an intensive and constant work in progress… I will need to correct several things (in particular regarding the second stage)… How is this related?

Well, I’m also planning to do one CEV… In fact, from some time now that I have an early CEV based on an Apollo capsule shape… I was just waiting for the 60 days study to re-start working on it…

Ooops, this forum does not seems to allow direct image links, so if you wish to see that work in progress, please go to my site during this weekend, and click in LivePics (upper right corner or, on left menu, Orbiter >> Live Mission). I use that page to transmit my Orbiter simulator playtime (including also development sessions)… Will later upload / attach the current picture into this thread.


The capsule has a base diameter of around 5.5m… Even if it had 5.1m… It is much bigger than an Apollo! I think that the public in general is not aware of that “little” detail when looking at the CEV (and lunar lander) images and when saying "Ho, look, it is just another Apollo!"…

Looking at my very crude wip model (I made the materials transparent for better visibility):

- Astronauts have some considerable space available… I still need to model stuff such as the seats, lockers, wc(?), etc, etc… but you can see that a nominal crew of 4 persons will still be comfortable.

- You can also see that how this design can be adapted to several roles: 6 persons can be transported to and back from ISS… I would even say that emergency design variants would be even capable of transporting… say up to 10 persons!

- EVA: good points there. Have no clue about that… If having an airlock then such airlock would have to be in the nose area and the docking port would have to double as EVA door. Of course that this would only allow EVA when the CEV is not docked at something… Unless there is a frontal mission module having also an airlock and EVA door and frontal docking port.

Regarding NASA's tradition with Apollo, mission modules were discarded in the past because it seems that the only thing they would be needed for would be for astronauts to have extra space for exercise and a better sleeping area

And this CEV has probably more space per person than an Apollo CMD… So, I would say that in the near future, there is some possibility of not existing any mission module for the CEV… If that is the case then it means that yes, astronauts would have to depressurise the whole capsule to do any eventual EVA.

But such EVA would not be a regular situation… So, I guess that the CEV will not have any airlock and that if the mission requires one planned EVA (talking here about complex jobs), the airlock will be in another component…

Hummm, I would like to see at least one kind of Mission Module… Something like a kind of space tug, mixed with an integrated airlock and with a robotic arm… That vehicle would stay in orbit and ready to rendezvous with a CEV if needed to fix satellites or… do some station building…

I hope that in the long-term future NASA also uses the heavy lift capability and a more Russian approach in that regard… It is simply insane to build a space station by grouping small components and requiring a big number of sequential missions and lots of EVA! The best is to do like the Russians: fewer launches, stronger and more autonomous station components… the only thing missing is heavy lifter… Think about a MIR where the modules are Skylab sized: now, that would be a true space station!

Oooops, back to CEV mission modules: if they ever appear, I think it would make sense to launch such component with the CEV launcher: hummm, that would most probably require a 5 segment SRB… And perhaps it would be not much nonsense to say that such module could be launched in the bottom of the CEV (requiring 180 pitch + docking manoeuvre, like Apollo with Lunar Module): this would be perhaps safer regarding escape / abort situations during ascent (having in mind the size of the CEV capsule.)

And there it goes a little more of my blablablablabla

António

[simcosmos]

WIP: like promised, here goes a pic where I'm starting to play with the interior of an Apollo based capsule for the CEV concept that will be integrated (in any future moment) ontop of the SRB launcher Orbiter addon…

More visual updates about the ongoing 3D model / addon preparation will be made on my site's LivePics page. Those updates will not be regular: it all depends of free time.

Meanwhile, if someone wishes to continue the discussion about hypothetical "Apollo" CEV layouts and, in particular, about the interior of one 5.5m base diameter capsule, it would be fun: for the moment I'm trying to do a kind of mix with the Apollo command module and the Shuttle interior (WC included)

Bye,
António

[kraisee]

simcosmos - 25/9/2005  1:58 PM

WIP: like promised, here goes a pic... [SNIP]

Only thing I can suggest is remember to keep all the real heavy items as low as possible, near the TPS shield.   This will be necessary to provide the unpowered self-correcting re-entry attitude Apollo had.   Are the people going to be the heaviest items aboard?

I can't help but feel that there will be a lot more space inside the capsule than what you've shown there.   I think there will be a simple system of mounting points on the walls for different types of 'cargo' units.   Each mounting will probably be generic enough to take either a persons seat, or an equipment rack for hardware, and they'll be largely interchangable (except probably where the pilot and commander console locations will be).   Other than that, I think it will be made pretty spacious and uncluttered, to provide the maximum amount of versatile space possible.   Computer systems are a lot more compact these days, even compared with STS.   And it won't require an enormous amount of internal supplies as most will be provided by the Service Module just like Apollo.

Oh, and I would expect one of the hatches to be an airlock arrangement too.   Probably the exterior side hatch so EVA's can still be performed without depressurizing the entire craft, even while docked to something.

Just my 2c in case its helpful

Oh, and don't forget to design it with 'go faster stripes' and a huge rear wing on it - which will obviously make it go much faster!   LOL

[rsp1202]

Now we're getting somewhere. Thanks to all for the replies and to the editor for reposting this question/thread in proper forum. It's good to see graphical representations on perspective; it was hard to picture difference in volume, etc., between Apollo and CEV and how a crew and equipment could be "packaged" efficiently, but now it's becoming clearer. Especially when you consider the notional CEV is for four astronauts; six crew only for short flights to ISS or emergencies, the Mars version totally different.

I would still refer all to the thumbnail graphic posted on Nasawatch/SpaceRef a few weeks back showing an external view of exploded biconic CEV with attached mission module and service module, in an excellent example of how to pull off a CEV. Wish a larger picture could be posted.

As time goes by, I look forward to the artists/designers/engineers on this forum posting their design ideas. I'm willing to become a conehead.

[gladiator1332]

I liked the design on NASA Watch as well. THe biconic CEV add on for orbiter had a cylinder-type Service module, however, I preferred the cone shaped service module:

I see Lockheed going with something like this, maybe not in biconic form...picture the lighter shaded section with an ablative heat-shield on the bottom.

[Avron]

kraisee - 25/9/2005  5:39 PM

Oh, and I would expect one of the hatches to be an airlock arrangement too.   Probably the exterior side hatch so EVA's can still be performed without depressurizing the entire craft, even while docked to something.

Looks like the passageway to the docking hatch at the pointy end could be used as an airlock.

[gladiator1332]

rsp1202 - 25/9/2005  6:08 PM

Now we're getting somewhere. Thanks to all for the replies and to the editor for reposting this question/thread in proper forum. It's good to see graphical representations on perspective; it was hard to picture difference in volume, etc., between Apollo and CEV and how a crew and equipment could be "packaged" efficiently, but now it's becoming clearer. Especially when you consider the notional CEV is for four astronauts; six crew only for short flights to ISS or emergencies, the Mars version totally different.

I would still refer all to the thumbnail graphic posted on Nasawatch/SpaceRef a few weeks back showing an external view of exploded biconic CEV with attached mission module and service module, in an excellent example of how to pull off a CEV. Wish a larger picture could be posted.

As time goes by, I look forward to the artists/designers/engineers on this forum posting their design ideas. I'm willing to become a conehead.

That was my favorite design so far. I like the Apollo-type capsule design NASA has now, however, as a Big Gemini fanatic, to see the design that appeared on NASA Watch thrown away is especially painful. Sure the biconic had many differences form Big G, however, I looked at it as an evolved Big G. The big problem with Big G was the hatch in the heatshield. They had another module for docking operations, however, this was not part of the re-entry module, therefore there needed to be a door in the heatshield to access this area of the spacecraft. The biconic we see on NASA Watch got rid of the need for this, as there was no need for a heatshield.

But say if we took that biconic deisgn and made it into a capsule. Would the hatch in the heatshield still be a problem? I mean, haven't we learned enough from the Shuttle (landing gear doors) that having a hatch in your heatshield is no longer a problem? All of this is for if you want some crew space back in that conical service module. It would be nice to have some extra room, and a rear docking port would then be possible.

Even thoug many on here will believe Boeing and LM will follow NASA's concept as close as possible, I just don't see LM doing this. I mean, this is the company that put out a lifting body when everyoen else was pointing towards a biconic or a capsule. THey most likely will have to go with some sort of capsule, but why not get a little innovative with what they do. Where's the fun in the competition if both teams spit out replicas of NASA's concept?

[MKremer]

But say if we took that biconic deisgn and made it into a capsule. Would the hatch in the heatshield still be a problem?

Since the heat shield is supposed to be jettisoned, adding a hatch to the center of it could turn out to be quite expensive, not only in construction, but in the technical design and testing/certification.

To add: You'd end up needing two hatches - one for the main CEV body, and a separate one for the heat shield. That's adding a lot of complexity to what's supposed to be a KISS design for an ablative, discardable heat shield.

[gladiator1332]

So to keep with the KISS principle, then the Service module obviously will not have any area for the crew and the dokcing port will be in the front. I'm afarid the extra hatches would be a waste of weight just to add a little more room for the crew.

[gladiator1332]

Someone on the Orbiter forum brought this up:

"But I am not sure if the shape is suitable for a 'tail-first' reentry. I think the overall shape is too slender. The capsule might tumble if it enters the atmosphere backwards."

WHat do you guys think...would that spacecraft be stable?

[AndyMc]

Hi,

I think that as long as the center of gravity of the capsule is low enough (towards the shield) it won't tumble out of control. This is probably more difficult to do the longer the capsule is.

Cheers,

[gladiator1332]

So it would be a good idea to store as much of the needed caro in the back...food lockers in the back, the two pilots are up front and the two or three crew sit in stowable seats in the back. They get to orbit, stow the seats and then they can reach the storage lockers.

[AndyMc]

Hi,

I found an old thread from yarchive.net discussing this very issue. http://yarchive.net/space/apollo/lifting_reentry.html

There's a guy called Henry Spencer in most of the threads who seems to know the answer to most questions. Anyone know who he is?

[Edit] http://www.hq.nasa.gov/office/pao/History/alsj/henry.html - Now I know!

Cheers,