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#126 2005-10-21 15:28:17

publiusr
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Re: Post central for information on CEV IV - Before thread #3 melts down

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#127 2005-11-18 06:59:33

SpaceNut
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Re: Post central for information on CEV IV - Before thread #3 melts down

Well we have been waiting for more than just pictures but could we have at least got something more than a mockup.

cev-mockup-bg.jpg

Mockup Provides Early Glimpse Of New Space Exploration Vehicle

Johnson Space Center in Houston has started building a full-sized mockup of the new craft's cockpit in its Space Vehicle Mockup Facility. But the next generation spacecraft needs more than diagrams, three-dimensional or not, for they can only go so far in helping engineers understand what layouts best suit the job at hand and the humans involved.

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#128 2005-11-18 09:41:59

jabe
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Re: Post central for information on CEV IV - Before thread #3 melts down

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#129 2005-11-18 09:55:42

GCNRevenger
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Re: Post central for information on CEV IV - Before thread #3 melts down

Good, maybe now it will start becomming real in the minds of Congressmen that this is the future, and not the dead-end and dying ISS.


[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]

[i]The glass is at 50% of capacity[/i]

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#130 2005-11-18 11:30:13

SpaceNut
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Re: Post central for information on CEV IV - Before thread #3 melts down

Thanks for the link it does appear to be an employee news letter intended for internal propaganda more than what most people really want to see. Things like this should be made known to all. You would think that it would be on there main website front page or even under the CEV links. That however is not the case.

GCNRevenger congress is definitely a hard nut to crack when all they focus seems to be on the dollars but who can blame them when they hear of billion dollar cost overruns such as the NPOESS to the tune of as Much As being $3 Billion Over Budget.

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#131 2005-12-13 07:19:10

SpaceNut
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Re: Post central for information on CEV IV - Before thread #3 melts down

With the first stage all locked up by ATK NASA pauses on CEV supplier selection

NASA is delaying its selection of a Crew Exploration Vehicle (CEV) prime contractor and has issued the competing consortiums with more changes to CEV requirements.

“Downselect will not be in March, it will be sometime in 2006,” says NASA Exploration Systems Mission Directorate constellation systems division director Michael Hecker.

The downselect will pick the winner of Phase 2, the second part of the CEV solicitation process, which began in March this year.

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#132 2006-01-05 15:24:55

SpaceNut
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Re: Post central for information on CEV IV - Before thread #3 melts down

It looks like Nasa Glenn has chosen to go with a Water Cooled Copper Nickel Rocket Engine Nozzle

NASA/GRC plans to issue a Request for Quotation (RFQ) for one water cooled copper nickel rocket engine nozzle using Rhedco Inc.'s proprietary process. NASA/GRC intends to purchase the item from Rhedco, Inc. on a sole source basis.

So much for others being able to build the same vehicle....

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#133 2006-01-12 12:43:50

Commodore
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Re: Post central for information on CEV IV - Before thread #3 melts down

Methane propellent dropped from LSAM/CEV

Methane was chosen because when we get to Mars it's a potential in-situ resource,' said one of the sources, speaking on conditional of remaining un-named. 'The argument was to concentrate on the Moon now and not build towards a future target, not to think that far ahead. Moon first, Mars is a long way away.

Can't say I disagree. It made little sense to go to the moon to extract H2O and then not be able to use it. Though methane is easier to store. But there will be plenty of opertunities to test menthane production and rockets on Mars via sample return missions.


"Yes, I was going to give this astronaut selection my best shot, I was determined when the NASA proctologist looked up my ass, he would see pipes so dazzling he would ask the nurse to get his sunglasses."
---Shuttle Astronaut Mike Mullane

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#134 2006-01-12 13:57:35

John Creighton
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Re: Post central for information on CEV IV - Before thread #3 melts down

Methane propellent dropped from LSAM/CEV

Methane was chosen because when we get to Mars it's a potential in-situ resource,' said one of the sources, speaking on conditional of remaining un-named. 'The argument was to concentrate on the Moon now and not build towards a future target, not to think that far ahead. Moon first, Mars is a long way away.

Can't say I disagree. It made little sense to go to the moon to extract H2O and then not be able to use it. Though methane is easier to store. But there will be plenty of opertunities to test menthane production and rockets on Mars via sample return missions.

Methane has superior performance. The really reason is perhaps a shortage in available dollars or engineering man hours.


Dig into the [url=http://child-civilization.blogspot.com/2006/12/political-grab-bag.html]political grab bag[/url] at [url=http://child-civilization.blogspot.com/]Child Civilization[/url]

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#135 2006-01-12 15:20:42

Rxke
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Re: Post central for information on CEV IV - Before thread #3 melts down

The argument was to concentrate on the Moon now and not build towards a future target, not to think that far ahead. Moon first, Mars is a long way away.

And decisions like these, step by little step, make it an even longer way away.

It will make a future mission more expensive, because everything in the VSE will end up as Luna-only hardware.

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#136 2006-01-12 17:03:21

Commodore
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Re: Post central for information on CEV IV - Before thread #3 melts down

Only if they intended to use the methane SM/LSAM engines on either Mars landers or transit stages, which I doubt. You can't really scale those things cheaply.

The big concern now is boil off. Prepositioning reliquidfying equipment in LEO and LLO might be required for long term missions. Which if done right can be turned into an advantage.


"Yes, I was going to give this astronaut selection my best shot, I was determined when the NASA proctologist looked up my ass, he would see pipes so dazzling he would ask the nurse to get his sunglasses."
---Shuttle Astronaut Mike Mullane

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#137 2006-01-12 18:45:49

GCNRevenger
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Re: Post central for information on CEV IV - Before thread #3 melts down

Methane propellent dropped from LSAM/CEV

Methane was chosen because when we get to Mars it's a potential in-situ resource,' said one of the sources, speaking on conditional of remaining un-named. 'The argument was to concentrate on the Moon now and not build towards a future target, not to think that far ahead. Moon first, Mars is a long way away.

Can't say I disagree. It made little sense to go to the moon to extract H2O and then not be able to use it. Though methane is easier to store. But there will be plenty of opertunities to test menthane production and rockets on Mars via sample return missions.

Methane has superior performance. The really reason is perhaps a shortage in available dollars or engineering man hours.

No. Methane actually has inferior specific impulse (~360-390sec vs 450-460sec) to H2/O2 engines by a signifigant margin, and switching to H2/O2 will increase payload capacity now by a good bit, and a bunch later with Lunar LOX. This is particularly true because Oxygen accounts for about 80% of the total propellant mass of the H2/O2 mix. Although there will be a higher tank mass penalty for H2/O2 for such a small vehicle, O2/Methane will still come out a loser pound-for-pound. The only big issue is long term storage, which will require a fuel condenser. However, if you are staying at a Moon base with an ISRU fuel condenser anyway, this should not be a big deal.

There is also the bennefit that a light weight and inexpensive mature H2/O2 engine of the appropriate size is already available off the shelf with only modest modifications for use, the RL-10. You can buy one off the shelf right now today, make some modifications to the control linkages and will probobly work.

This engine was used by the DC-X and proven as a soft-landing engine with a very wide range of throttle settings. It is also the only engine used by Delta-IV Medium, Delta-IV Heavy, Atlas-V, and Titan-IV Heavy upper stage with its high efficiency and reliability. Oh, and it has proven to restart after hours or even days between firings. The only problem will be accomodating the bigger vacuum-rated nozzle.

The best part is though, NASA doesn't have to build a new engine from scratch, which was a cost promising to spiral out of control already. This would be equally true if NASA decided to go with a Hypergolic arrangement, which is not quite as efficient as O2/Methane, but its higher density partially offsets this advantage. Small hypergolic engines are extremely reliable in general, and are pretty safe if built properly.

Edit: However... there is no practical way for the service module to be H2/O2 powerd. It would have to be either methane or hypergolic. That doesn't mean the Lunar acent module and CEV service module will be powerd by the same fuel/engine, but it does make sense for them to.


[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]

[i]The glass is at 50% of capacity[/i]

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#138 2006-01-12 22:19:49

John Creighton
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Re: Post central for information on CEV IV - Before thread #3 melts down

Methane propellent dropped from LSAM/CEV



Can't say I disagree. It made little sense to go to the moon to extract H2O and then not be able to use it. Though methane is easier to store. But there will be plenty of opertunities to test menthane production and rockets on Mars via sample return missions.

Methane has superior performance. The really reason is perhaps a shortage in available dollars or engineering man hours.

No. Methane actually has inferior specific impulse (~360-390sec vs 450-460sec) to H2/O2 engines by a signifigant margin, and switching to H2/O2 will increase payload capacity now by a good bit, and a bunch later with Lunar LOX. This is particularly true because Oxygen accounts for about 80% of the total propellant mass of the H2/O2 mix. Although there will be a higher tank mass penalty for H2/O2 for such a small vehicle, O2/Methane will still come out a loser pound-for-pound. The only big issue is long term storage, which will require a fuel condenser. However, if you are staying at a Moon base with an ISRU fuel condenser anyway, this should not be a big deal.

Hey, thanx for putting words in my mouth. Methane is superior to hypergolic engines in specific impulse and superior to hydrogen in terms of boil offs. Weren’t you at one time advocating month long exploration missions?

There is also the bennefit that a light weight and inexpensive mature H2/O2 engine of the appropriate size is already available off the shelf with only modest modifications for use, the RL-10. You can buy one off the shelf right now today, make some modifications to the control linkages and will probobly work.

Which as I said is the real reason. Money. Cha Ching Cha Ching. NASA will never advance if it doesn’t invest a significant portion of its dollars in engineering research  and development.  You can put off the cost now but it will just mean you will pay a bigger penalty later. From a man that said Zubrin was rushing to mars it sounds like you want to rush to the moon. wink

The best part is though, NASA doesn't have to build a new engine from scratch, which was a cost promising to spiral out of control already. This would be equally true if NASA decided to go with a Hypergolic arrangement, which is not quite as efficient as O2/Methane, but its higher density partially offsets this advantage. Small hypergolic engines are extremely reliable in general, and are pretty safe if built properly.

I think you are repeating yourself.

Edit: However... there is no practical way for the service module to be H2/O2 powerd. It would have to be either methane or hypergolic. That doesn't mean the Lunar acent module and CEV service module will be powerd by the same fuel/engine, but it does make sense for them to.

Sounds like you are backtracking some.


Dig into the [url=http://child-civilization.blogspot.com/2006/12/political-grab-bag.html]political grab bag[/url] at [url=http://child-civilization.blogspot.com/]Child Civilization[/url]

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#139 2006-01-12 22:23:55

BWhite
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Re: Post central for information on CEV IV - Before thread #3 melts down

A methane RL-10 has already been built, as I recall.

Also, disposable LSAMs need to be temporary otherwise no sustained presence is possible.

At first I was dismayed by the cancellation of plans for a methane ascent engine but then realised (thanks, google!) that steam reformation is a leading method of creating pure hydrogen.  So? Well, store methane and then mix with water at 1100 C and pure H2 and CO2 comes out. The H2 comes from both the water and the methane.

Steam reformation might take less energy than cracking H2O by electrolysis and at least some of the steam production can be done (started?) by passive solar.

= = =

Edit to add: Pratt & Whitney doesn't seem worried that a methane RL-10 is any big deal. Or at least one author at P&W

http://pdf.aiaa.org/preview/CDReadyMJPC … 4_4210.pdf


Give someone a sufficient [b][i]why[/i][/b] and they can endure just about any [b][i]how[/i][/b]

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#140 2006-01-13 08:15:25

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Re: Post central for information on CEV IV - Before thread #3 melts down

... and let's not forget that the possibility of lunar water ice means that H2 would also be available for refueling the LSAM completely. A fully refueled LSAM could shuttle between the surface and LLO and hopefully enable a CEV to dock with it directly without the need for a HLV launch each time to bring a fresh one.


[color=darkred]Let's go to Mars and far beyond -  triple NASA's budget ![/color] [url=irc://freenode#space]  #space channel !! [/url] [url=http://www.youtube.com/user/c1cl0ps]   - videos !!![/url]

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#141 2006-01-13 09:20:24

BWhite
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Re: Post central for information on CEV IV - Before thread #3 melts down

I am not sanguine about recoverable lunar ice.

If its there, great. But its not a sure thing.


Give someone a sufficient [b][i]why[/i][/b] and they can endure just about any [b][i]how[/i][/b]

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#142 2006-01-13 14:22:39

GCNRevenger
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Re: Post central for information on CEV IV - Before thread #3 melts down

Sounded like you were implying that Methane was superior to all potential propellant options.

By "long missions" I was aiming for two weeks. If NASA thinks that solar arrays aren't practical for more than one week on the surface or so, then that is probably as good as we can expect. In either case, Hydrogen for acent fuel would not have excessive boiloff.

Actually, the plan to use Methane for the acent stage and service module if a move that reduces the liklyhood that a Lunar installation will be viable in the longer term, since a few added tonnes of payload would eliminate the need for seperate supply flights and permit more equipment to be brought per sortie. There is also the possibility that the LSAM could be reused and a lighter rocket, like TheStick or the Delta-IV HLV+, could bring up a mini-EDS instead of needing the big SDV and full size EDS. Switching to Hydrogen is not a rush to the Moon, its just not sacrificing the chances of a sustained presence on the Moon any more then we have to on the way to Mars.

I am still chewing over the idea of saving money by using the same engine for the LSAM acent stage and the CEV service module... if NASA really is abandoning the methane engine, then the only viable choices for the SM are lower performance fuels like Hypergolics, Ethanol, or Kerosene. Of the three, Hypergolics are probobly preferred for their reliability and temperature tollerance.

NASA may improve the chances of a sustained presence on the Moon by using Hydrogen for the LSAM acent and Hypergolics for the SM, but this will nessesitate building a Hypergolic engine. If this is the case, it may be easier then building a Methane engine from scratch, since NASA already has an engine to copy from: the old Apollo engines. So, you trade the LSAM acent engine for RL-10 and the CEV SM for Hypergolics, you get increased LSAM payload, increased bennefit from ISRU (probable elimination of supply flights), at the cost of (re)developing a Hypergolic engine.

Considering the noises going around that the pressure-fed Methane engine envisioned for the CEV-SM/LSAM was going to be a big ticket item and development would be a show-stopper (good chance of price gouging going on), then (re)developing a Hypergolic engine might save some big money. Even if the Hypergolic engine is used for the LSAM acent module too, its higher density will partially offset the lower specific impulse, and still save big money.

I don't care for the short-term-centicity of this last option of hypergolics for both (avoiding development of a modified man-rated RL-10), but if NASA has to develop CEV while simultainiously flying Shuttle/ISS, then this route might be worthwhile to absolutely minimize the amount of engine development required to build both vehicles. Perhaps a future Hydrogen-powerd LSAM acent vehicle could be substituted for the Hypergolic powerd one, funding post-Shuttle permitting.


[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]

[i]The glass is at 50% of capacity[/i]

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#143 2006-01-13 21:16:37

Commodore
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Re: Post central for information on CEV IV - Before thread #3 melts down

Hyperglocs are likely to be avoided do to toxicity and the fact that they are useless for ISRU.

But ban we can pin done just how much wiggle room we actually would have with LOX/LH engines?

Would we have 1, 2, even 3 weeks to launch the CEV before the EDS and/or LSAM boiled off too much to be useful?
Would the CEV have enough fuel after the 2/2.5 week mission to get people home?
What about 6 months docked to the ISS?
How much mass would we lose to insulation?

One way to solve the boil off problem is to preposition fuel depots with fuel condensers at each end of the trip. That way you can dock with it and you'll only lose a tiny amount of fuel during transit.

On the Luna end, decent modules can be prepositioned, launched yearly in magazines of 4-6 (depending on weight, I think the current LSAM weights in at 40-50 tons, so the DM alone should be 20-30tons) at time and propelled via and expanded EDS, at the lost of only 2 CaLV launches instead of 4-6, along with a modified CEV serving as a reusable accent module. Once docked at the Lunar Depot, the fuel in the LSAMs is off loaded into the depot tanks were it can be recirculated indefinately. The accent stage automatically intergrates with the first decent stage. When crews arrive, they dock at the depot and offload the CEV fuel to depot tanks, again to avoid boil off, which might be overkill for week long missions, but likely vital for missions of 6 months or more, and move to the LSAM, fuel it up and go on their merry way. Repeat in reverse to go home. Over the long term its a perfect place to store reuseable landers, and to deliever harvested fuel to.

On the Earth end, a simple tank with fuel condensers. And a small EDS that sends the CEV to Luna, and then returns to the depot. Fuel is provided by a single CaLV launch, with enough fuel for several missions. Later, when and if Lunar fuels are available, it can come from there.

Both are nearly identical. The only difference for the lunar version is the the mechanism intergrate the AM to the DM. Both could likely be launched tankless with a single CaLV launch, if have their own built in engines (likely for station keeping). Deployment on the lunar end would begin with the launch of the main spine, fuel condensers, and docking apperadus. The second launch would feature the main tank, full of fuel. The same would be done on the Earth end first. For the lunar depot the tank of fuel would be used to propel the depot to lunar orbit, with some extra for stationkeeping. Then the decent module magazine would be launched, docking with the Earth depot to perserve fuel and await the EDS. The landers would then fuel up, dock with the EDS, and head to luna. Once docked at this depot they defuel, and the EDS makes permenent contact with the lunar surface for salvage years down the road.

This requires a lot of fuel transfers that we have little operational experience with, especially in zero g. But all the hardware can be ported directly to the surface down the line, and we have to push the envelope somewhere. Plus by launching DMs in bulk and reusing the AM we save on CaLV launches, though at the cost of 4 flights to launch the depots, but at a landing rate of 5 per year, we pay for that in just a couple years. Not to mention it eliminates all threat of mission loss by boil off, and builds in growth options for the architecture

As far as development costs, it would all be dependant on immediate retirement of the Shuttles, and the CEV/CLV, and the CaLV, and probably the mid-range EDS envisioned in the ESAS, primarily for ISS completion, all by roughly 2012. Not impossible if we get going. Should the Shuttle launch in May and the same problem repeats itself, I don't think there will be any other choice. Following that, the high end EDS is little more than an extention of the one developed to finish the ISS. The low end one to send the CEV to lunar orbit is little more than a slightly larger SM. The use of a CM for an accent module eliminates or greatly reduces a development cycle. The depots are the greatest expense, but the hardware is the first step to setting up similar structures on the Moon and Mars later.


"Yes, I was going to give this astronaut selection my best shot, I was determined when the NASA proctologist looked up my ass, he would see pipes so dazzling he would ask the nurse to get his sunglasses."
---Shuttle Astronaut Mike Mullane

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#144 2006-01-14 08:58:47

GCNRevenger
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Re: Post central for information on CEV IV - Before thread #3 melts down

Hydrogen isn't going to be used for the CEV SM one way or the other

Prepositioning fuel depots? No the EDS can only put 125MT in Earth orbit not on a Lunar transfer orbit, so it could only carry two decent stages loaded. Also, it could only carry ~50MT of fuel in a tank, which is only enough for two or three trips from the surface and back.

Again, why bother? If the EDS can send one CEV and one LSAM, then there isn't any good reason to send two LSAMs (or fuel for them) and CEVs seperatly. Don't forget, the current arrangement calls for the LSAMs to carry Lunar orbit capture fuel, so the CEV couldn't enter Lunar orbit and return to Earth after, it would be too heavy for the TheStick. There isn't going to be any "modified CEV acent module" either, the change would be so radical that it would be a totally different vehicle.

Too much docking, too much fuel transfer, not any bennefit. As long as all the fuel is brought from Earth, then it doesn't make any sense to reuse anything. The cost of building reuseability into the system wipes out any bennefit. And I do mean any. The EDS stage is going to be simple. Its going to be dumb. Its going to be cheap. Just a tank with a pair of J-2's on the back... There isn't any good reason for a fuel depot if you can ship fuel out in bulk with the HLLV when you need it instead of storing it on a unmanned space station in a partially stable orbit with batteries and gyros to break down.

Returning the mini-EDS to Earth? Why? That costs alot of rocket fuel to return it to Earth, and since you have to bring it from Earth in the first place would make it too heavy to launch with TheStick. No aerobraking either, so it has to carry Earth orbit capture fuel too. You would have to go and modify Boeing's Delta-IV HLV to make it powerful enough. But why would you bother in the first place? The mini-EDS is just going to be a modified heavy Centaur stage, which only cost a few tens of millions at most. As US-built rockets go, cheap...

The whole thrust of the above is that as long as all the fuel is brought from Earth, then the cost of reuseability is unjustifiable. It costs the same amount to launch rocket fuel as it does space vehicles, and the money you save by not having to send fresh vehicles is always going to be wiped out by the cost of reusing them and bringing additional fuel to reuse them with. Returning EDS stages to Earth costs fuel (more then the TheStick can carry plus enough to push CEV), returning the spent LSAM acent module to LLO doesn't save you but a few tonnes at most, and so on. Giving the CEV the ability to brake into Lunar orbit will make it too heavy to launch, and making the mini-EDS do it is less efficient since you have to brake its mass too.

This plan is nothing like the current VSE plan, its full of terrible inefficiencies, useless space stations (in metastable orbit to boot), more docking events, the expense of reuseable vehicles without bennefit and so on. Simple, simple simple simple! The plan has got to be as simple as possible... your plan isn't. "Pushing the envelope" is a sure recipe for total fiscal and engineering failure; its the very last thing we need right now! Unless it provides some overwhelming bennefit, there is no compelling reason for it, reuse of the LSAM acent module a few times can't possibly be worth all this trouble.

Oh, and then you have to send (and risk) all the payloads and supplies you want to send to the Moon all at once on one HLLV shot with the LSAMs, which is a terrible deal.

And what of this mini-EDS being used to complete the ISS? It can't, its too heavy, and being a self-powerd maneuvering vehicle is nothing like the big dumb CaLV jumbo EDS, especially since it has to serve as upper stage.
-------------------------------------------------------------------

Now for reuseability and long-term LSAM acent fuel storage...:

The place to put the fuel depot is where the fuel will be needed the most: on the surface. On the surface and only on the surface, no space depots at all on any end.

There is no good reason to try and launch Earth-return fuel, the CEV has to be launched with a service module, and said module has enough fuel to do the job. Since you can't build a miniature discount-model Stick launcher, there is no reason not to send it up fully loaded.

There is no good reason to try and salvage the EDS, it would cost more then it would save. (see above)

The LSAM acent module, Hydrogen powerd, will land with only LH2 onboard at the base; there it will connect hoses to the ISRU plant to condense Hydrogen boiloff for later reuse, and for LOX loading when the time comes for the return trip. Thats all, nothing more.

Later, much later, after-we're-on-Mars-later we can think about full reuseability and not before... And when we do, we still don't need a fuel depot in Lunar orbit. A fully reuseable lander, powerd by Lunar Oxygen and imported Hydrogen, would launch several times over a short time period to refuel a second waiting vehicle in Lunar orbit. Just time your launches to coincide with the next payload, don't bother with a fuel depot.

This also gives time for AltSpace spaceflight to come into its own, like if Elon could come up with the Falcon-IX or Falcon-V tripple-barrel or someone suceeds where Kistler failed, that would make a huge difference to lugging Lunar transit fuel and payloads to orbit.


[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]

[i]The glass is at 50% of capacity[/i]

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#145 2006-01-18 11:16:01

SpaceNut
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Posts: 29,431

Re: Post central for information on CEV IV - Before thread #3 melts down

We have been talking about the engines for the cev for some time now and Nasa is just now thinking that they have a problem.

NASA Encounters Possible Problems With Crew Launch Vehicle Design

Sources report problems have been encountered in designing an expendable version (RS–25) of the current SSME (Space Shuttle Main Engine) for the CLV's second stage that can be air-started. Concerns have also been raised that a possible alternate second stage engine, a derivative of the Apollo era J-2S engine, may be underpowered for the task.

These sources also talk about interest on NASA's part of moving to using a 5 segment SRB (Solid Rocket Booster) as the first stage of the CLV instead of the initial plan to use the current 4 segment booster used by the Space Shuttle. In so doing, NASA would now be creating what would, in essence, be a wholly new launch vehicle.

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#146 2006-01-19 09:59:35

GCNRevenger
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Re: Post central for information on CEV IV - Before thread #3 melts down

*sighs*

I am starting to lose faith in NASA... has flying in circles for so long caused them to lose their skills? What happend to the SSME design team? The very least they could do is build an engine wuth a stretch nozzle + air-start ignition and worry about simlification after TheStick is about ready. Has NASA really lost even this minimal competance after just dealing with Shuttle maintenance for so long? Is that all they're good at anymore?

If the SSME isn't going to happen, whats going to happen with the big SDV heavy lifter? Could NASA drop the SSME and swtich to RS-68 engines instead?


[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]

[i]The glass is at 50% of capacity[/i]

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#147 2006-01-19 12:29:35

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 29,431

Re: Post central for information on CEV IV - Before thread #3 melts down

Just wondering too about Nasa these days especially when upstarts are attempting to do what they are not.
Since the leak on the changes to the LSAM for methane not being an effort I wonder if they should be paying attention to xcor. XCOR Completes Methane Engine Pulse Fire Tests

LOX/methane rocket engines show promise to provide higher performance
necessary for manned moon missions.  NASA, in its ESAS study of how to return
to the Moon, recognized the importance of LOX/methane: "The additional
performance benefit of a mature LOX/methane system ... provided the launch
mass capability to enable the 1.5-launch architecture, thus allowing for crew
launch on the single-stick SRB, which has the lowest [loss of crew]
probability.  The LOX/methane system was also desirable to eliminate the
operability issues related to hypergols and to enable the use of in-situ
methane on Mars and oxygen on the Moon and Mars."

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#148 2006-01-19 13:54:08

GCNRevenger
Member
From: Earth
Registered: 2003-10-14
Posts: 6,056

Re: Post central for information on CEV IV - Before thread #3 melts down

The operative phrase: "that are required for reaction control system (RCS) applications"

Its an RCS thruster...

In other words, its an itty bitty teeny tiny rocket engine, and about as far from the CEV-sized engine as you can get. The CEV engine must be pretty powerful, primarily because the engine is used to escape from the upper stage if there is a problem. The pointy escape tower on the top of the CEV is only effective during the early phase of launch when the SRB is burning, and is ejected shortly after seperation. The CEV service module engine is used for escape during the later phase of launch when it is being pushed by the SSME upper stage.

The same engine is (was?) slated to power the LSAM acent stage to get from the Lunar surface back to orbit, so it would need signifigant thrust too, especially to minimize inefficiency due to gravitational losses (more thrust, less gravitational loss).

Also, the X-COR engine is self pressurized and not helium pressurized, so its not like the engine called for for the CEV service module even more. Basically, X-COR included the CEV blurb to make themselves sound good. NASA is possibly going to abandon Methane for the Moon primarily because of the time penalty associated with it, and if X-COR is just now building puny maneuvering engines, there is no reason in the world to consider them for the CEV/LSAM engine.

That said, this is probably the easiest and best entry point and proving ground for the VSE for an AltSpace company, to come up a working medium-sized pressure-fed Methane engine. Such an engine should not be impossibly hard for an AltSpace firm to build (although it would be quite hard), and if their leaner/meaner engineering could beat the slow/plodding regular NASA people, then that would really save NASA some big headache. It would also be a big enough project to really make a name for theselves... doing anything much smaller, and you risk just being one of Lockheed/Boeings lacky "subcontractors."


[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]

[i]The glass is at 50% of capacity[/i]

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#149 2006-01-27 17:06:07

publiusr
Banned
From: Alabama
Registered: 2005-02-24
Posts: 682

Re: Post central for information on CEV IV - Before thread #3 melts down

Not holding my breath.

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#150 2006-01-30 05:13:40

maxie
Banned
From: Europe
Registered: 2005-02-15
Posts: 84

Re: Post central for information on CEV IV - Before thread #3 melts down

Astronautix article about CEV. Interesting to read...
http://www.astronautix.com/craftfam/cev.htm

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