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darkenfast
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« on: 10/31/2005 09:41 PM » |
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First off, I've just joined because another forum, "Space.com" is going through a mud-slinging troll infestation. Labelling people "murderers" who have given years to making the Shuttle work is not my idea of rational debate. But, anyway, on to the CEV. Like many others, I was at first dismayed when I saw the early drawings of "Constellation" in the press. How could they call an Apollo capsule an STS follow-on? It took a while, but the more I looked the better it got. First, I downloaded the Reliability and Crew Safety Assesment that SAIC did for ATK's proposed launcher. Although the upper stage has changed engines, the overall numbers should remain the same, i.e. this vehicle should be a lot more reliable and "escapable". I kept looking.
Next, I drew some old-fashioned pencil drawings of the CEV capsule (once the 5.5m and 32.5 degree sidewall were announced), and put them next to Apollo, Shenzhou, and Soyuz. Yowza! This is a much larger spacecraft. Even without the extra volume of a lander, the four astronauts on a lunar mission, will have nearly the same space per-person as a seven person shuttle crew. The most crowded part of a lunar mission will be the surface stay, but they will spend a lot of time on EVA. And then there's those tantalizing Methane/LOX engines...hmmm.
I also considered the blunt-body capsule vs. lifting body/wings etc. arguments. There is nothing more inherently advanced about wings than a heat-shield and parachutes. For a spacecraft that is going to travel millions of miles, it makes sense to adopt the shape where the re-entry and landing impinge the least on the other requirements; such as strength, weight, shielding and interior space. That left blunt-body and lifting body. Lifting bodies can apparently perform a more gentle re-entry, but the G's are pulled in a different direction than during lift-off. That requires either pulling the G's sitting up (as on the Orbiter upper deck), or moving the seats to a horizontal position. If a launch goes bad and the astronauts are facing a ballistic trajectory with high-G's (as happened on a Soyuz), then they have to change during the abort. Additionally, the thermal protection systems I've seen on the lifting-body proposals were not one-peice ablative heat-shields, which I believe are the more reliable choice (especially for lunar/interplanetary return). The Apollo-like layout of the couches, with the crew in the same postions facing the controls for all high-G, docking and other maneuvers, seems the best bet to me.
Unfortunately, the one thing the CEV won't have is a built-in airlock. There's no way a realistic one can fit, and frankly the craft would have to be a lot larger to incorporate one. Either a mission-specific module, the Lander, or simple cabin de-pressurization will suffice to cover the bases.
Dr. Griffith said it best when he pointed out that about halfway through the study the choice of the Apoolo shape emerged as the best choice. The physics of re-entry haven't changed. And, this is the only proposal I have seen which has even a remote chance of being funded.
The Shuttle, despite it's flaws (most of which were inherent in requirements forced on NASA from outside), has been a magnificent achievement. We have acquired so much experience in how to work in space that we would never have gotten any other way. The confidence that NASA and the astronauts now have is amazing compared to pre-shuttle. Remember the astronaut-concocted three-person space-walk? That's my favorite example of the kind of thing that would never have happened before. And, let us not forget that the STS is going to give us two new man-rated boosters (one of them Saturn V-class) at a fraction of the cost of a new system. As I have said before on other forums, in the Shuttle, we had a Mack truck, good for a certain job. Now it's time to build a Land-Rover and go exploring again.
Thanks for reading all this!
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« on: 10/31/2005 09:41 PM » |
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Flightstar
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« Reply #1 on: 10/31/2005 10:43 PM » |
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A brilliant first post. Welcome to the site. You will like it here as respect is upheld and there is a zero tolerance policy on anything distasteful.
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Spacely
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« Reply #2 on: 10/31/2005 10:50 PM » |
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darkenfast, could you scan your sketches in and post them? I'm curious to see the size of the CEV relative to Soyuz, Shenzou, et al.
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SRBseparama
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« Reply #3 on: 10/31/2005 10:50 PM » |
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A very good point made on the way the STS program has translated into the CEV and SDLV projections given the SRBs as one example. It's not a decision to stop the STS program, its a progression to the next stage.
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Tahii
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« Reply #6 on: 11/01/2005 05:42 AM » |
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That was a great first post - quite a nice read. Cheers
Welcome to the forum.
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kraisee
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« Reply #7 on: 11/01/2005 06:50 PM » |
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Yes, welcome to the forum. Your first post is indeed very insightful. I took the chance to prepare a drawing based on what you said. It's fairly accurate, based on information and pictures from Mark Wade's Astronautix.com website, showing the various sizes of the craft. The CEV is obviously just a re-work of the Apollo image, but is the correct diameter acording to Griffin's statements a few weeks ago. Hope it helps to visualise what you were saying... ![]("<a) http://68.205.251.208/Public/CEVSize.jpg">
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FransonUK
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« Reply #8 on: 11/01/2005 08:02 PM » |
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That's a good image to compare with. I didn't know that there seems to be more space inside the CEV. I know it's a four seater, but my hope was they wouldn't be like sardines.
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RedSky
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« Reply #9 on: 11/01/2005 09:41 PM » |
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That comparison is really great. Any chance that you could put a Kliper on there? I think that would be quite an intriguing addition to see it with the other ships: Apollo update (CEV), Old Apollo, Soyuz update (Shenzhou), Old Soyuz, then Kliper.
Here is a reasonably good artists illustration of it based on the latest design version. The detail at RussianSpaceWeb.com says its length is 10 meters. This picture would probably make it a bit longer, since it still has its adapter ring with its orbital insertion rockets on it. That conical ring mostly surrounds the soyuz orbital module / docking adapter - sphere buried at the back behind the return lifting body part of the ship, but probably that ring only adds a few extra meters to that 10m length.
-RedSky
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darkenfast
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« Reply #10 on: 11/01/2005 10:28 PM » |
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Thanks for the warm welcome! I'm afraid I don't have a scanner, so I can't upload my drawings. I'm a pretty good amateur draftsman (the old-fashioned way), and I've been trying out different concepts for the CEV. Funny thing is, I ended up back with something very similar to Apollo. We know the outside shape (5.5m diameter, 33.5 degree angle on the side wall). A cone-shape means that you are going to have constraints on the interior shape that are hard to picture unless you draw it. Since I can't show you the drawings, I'll describe it (skip the rest, if you want). Then we'll see how far off I was when the real thing comes out!
Basically, the innards I'm guessing on (and I'm using spatial directions from Apollo), has four couches in a row. The Commander and Engineer (since it's mine, I've re-named the crew titles, because pilots are for airplanes), sit (lay) in the outside couches, while the center section (with either two or one couch), will probably be removed during flight. The spacing is a bit larger than Apollo to allow for different types of suits, and to give the two outside positions a little more room to work the attitude and translation controllers. The control panel has the duplicated flight controls to the outside, of course, with circuit breakers, and auxilliary controls towards the center. Sidewall hatch, rendezvous and docking windows and side windows are similar to Apollo, except that the side windows are round (stronger and more easy to put a variable rotating polarizer in, for glare. The upper aft bay (under the couches and towards the sidewall with the hatch) is open for suit storage and two sleeping positions. Along the aft bulkhead left-right centerline are four cargo boxes. If six people are on board, two boxes are removed and two additional couches are attached to the couch framework (which is on shocks). Right-hand and left-hand equipment bays contain life-support equipment.
The lower bay has three sectors. The center (viewed as you're standing on the aft bulkhead), has three standard racks for electronics, any science gear, and an optical sextant telescope developed from the Apollo system. These racks are about four feet from the foot of the center couches when they are in place. The right-hand sector contains the Waste Management System: the infamous zero-g toilet with a fold-out privacy screen; and some lockers. The left-hand sector contains the galley and some lockers. With the center couches stowed, there's a lot of room, especially in micro-gravity. The center-of-mass is offset towards the lower bay to allow for lifting re-entries. Other small lockers are all around the cabin.
I've drawn the tunnel to the docking hatch as conical, not cylindrical, to give room to work the hatch itself, which is at the forward end of the tunnel, unlike Apollo.
The actual shape of the pressure hull is similar to Apollo, to allow for tankage and reaction control motors around the circumfrence at the aft end, and the recovery system at the forward end.
I'm wondering if it would work to use one big heatshield-bag like the Mercury capsules did? This will will be simpler, and will avoid dropping the heatshield on someone (like Edwards AFB housing), if the landing is a little off.
Picture a room a little over 10 feet wide and about 12 feet long, with closets and cupboards all around. Put it on the top floor of a house under a sloping roof (on the short walls), and you have a pretty good picture of the space available. It's light years beyond any other capsule ever flown, and I believe it will be good vehicle to travel in.
Thanks!
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Flightstar
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« Reply #11 on: 11/01/2005 10:40 PM » |
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RedSky - 1/11/2005 3:41 PM
That comparison is really great. Any chance that you could put a Kliper on there? I think that would be quite an intriguing addition to see it with the other ships: Apollo update (CEV), Old Apollo, Soyuz update (Shenzhou), Old Soyuz, then Kliper.
Here is a reasonably good artists illustration of it based on the latest design version. The detail at RussianSpaceWeb.com says its length is 10 meters. This picture would probably make it a bit longer, since it still has its adapter ring with its orbital insertion rockets on it. That conical ring mostly surrounds the soyuz orbital module / docking adapter - sphere buried at the back behind the return lifting body part of the ship, but probably that ring only adds a few extra meters to that 10m length.
-RedSky
That's a lovely image of her.
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RedSky
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« Reply #12 on: 11/01/2005 11:08 PM » |
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Good to hear about all the interior design interest on the CEV interior you're doing, Dark. BTW, does anyone really know the reason why Griffin is insisting on the exact "Apollo" shape? I know, I know.. its been mentioned all the old entry dynamics testing that was done on that shape with Apollo... so we know how it works. But with the aerospace computing power available today compared with the late 1950's when that shape was designed, I can't see why a better alternative couldn't be tried. At least allow the contractors to submit something different. An old LockMart version for the CEV (before their new Dynasoar clone) had a more "barrel shaped" entry module. We know that also works... since its the Soyuz and Shenzhou shape. Wouldn't a somewhat more barrel shaped crew cabin with the same CEV planned new diameter add lots more volume than the Apollo-sloped sides? (i.e., Soyuz on steriods)
RedSky
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Shuttle Man
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« Reply #13 on: 11/01/2005 11:24 PM » |
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Yes, welcome to the site, Black. We have an excellent first number of hundreds posters here long may it continue.
Red: The reason the "apollo" style design remained was quiet simply relevant to it being the best 'proven' design for ballistic travel. Sure, there may be better out there, but this is tried and tested, hense it won out.
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gladiator1332
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« Reply #14 on: 11/02/2005 01:15 AM » |
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Welcome to the forums, and really nice post!
I too was not so sure about NASA's CEV choice at first, but about two weeks ago I went through the two threads posted previously that showed some of the size comparisons and I really saw how amazing and different this truly is. It really is the right way to go. And in its own way, the CEV isn't that ugly looking. Kinda like the Apollo LM, some look at it and see the ugliest thing to ever take flight, however, there is something truly beautiful about the LM.
I don't see going back to the "old days" as something bad, I see it as picking up where we left off a long time ago. I'm tired of people bashing the CEV because they feel its a step back. I am also tired of people saying the Shuttle was a complete waste. We learned many things from the Shuttle program, and how soon we all forget that the SRB's and the ET will be used to launch the CEV. If it weren't for all of those Shuttle missions, I would have little confidence in the SRB launcher.
Leave the sexxy winged spacecraft to Rutan and Virgin Galactic, and the other companies like them. NASA astronauts are brave men and wonen, they do not need the luxery of landing on a runway.
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