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#26 2006-05-21 13:34:47

Grypd
Member
From: Scotland, Europe
Registered: 2004-06-07
Posts: 1,867

Re: Engine Pod Economics

True single stage RLVs are beyond us at the moment. Even two stage RLVs will be expensive to develop but also are unlikely to have a large cargo capacity. Whatever happens there will be a need for a heavy lift option just so worthwhile payloads can be sent up.

For RLV's to deliver economy there has to be regular frequent flights and the TSTO RLV will need to be not only safety checked before launch they will also need to mated to the lower stage. It is possible to have throwaway upper stages so that heavier cargo's can be sent up but they will never have the single lift capability of a heavy lift rocket.

Another thing that RLVs do is that they lend themselves to being crew delivery systems. And for crew to be delivered there has to be a destination and the RLVs cannot put it there only Rockets can.


Chan eil mi aig a bheil ùidh ann an gleidheadh an status quo; Tha mi airson cur às e.

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#27 2006-05-21 15:13:52

Austin Stanley
Member
From: Texarkana, TX
Registered: 2002-03-18
Posts: 519
Website

Re: Engine Pod Economics

Sorry it took me so long to reply, Real Life (TM) intervens, on the plus side I could be seeing some serious dough if the chemical process I am developing gets purchased.

---------

The RS-68 and SSME version of the rocket really aren't interchangeable; the SSME with its lower thrust would suffer gravitational losses with the 10m tank and reduce payload. Each engine was designed to be paired with a given mass of propellant, with the RS-68 conciously being made to trade specific impulse for big cheap fuel tanks. As a result, RS-68 has 80% less parts but 50% more thrust and costs a third as much. You would have to go back to the narrower diameter and change back all the construction and launch hardware to the older size. Also, both engines might not be readily available, the SSME line might be closed for a long time if NASA goes with RS-68 now, and conversely the RS-68 line might be closed if the USAF "down selects" Delta without NASA buying engines. Restarting either line would be expensive.

You can't have your cake without penalty or risk

The amount of thrust generated by 5 SSME (5x1.8MN=9MN) and 3 RS-68 (3x2.9MN=8.7MN) is comparable, with the SSME actualy being slightly supperior.  So I see no reason why the SSME could not use the large 10m tank.  It's the SRB that provide most of the boost at launch anyways, as both engines (and most liquid fueled engines in general) have problems with gravitational losses.  As for either engine going out of production, I wouldn't worry to much in either case.  The SSME is not currently in large scale production and likely never will be, however Rocketdyne can still assemble new units as needed, and will not likely throw away this valuable capability even if the SSME is "downselected" as for the RS-68, returning them to service would only cost a fraction of their long term cost anyways, so I wouldn't worry about that to much either.

"But my main point is that OMS/RCS are absolutly not required, as the pod can be set on an apropriate balistic path before seperation. Nor is the heat-shield requied to be flat. A biconic heat shield"

I don't agree. Some attitude control will still probably be nessesarry without a high degree of self-righting capability, which will not be easy with a relativly flat shield. And it does have to be fairly flat, there is no room for the "point" of a biconic shield that gives it this advantage, plus a biconic shield has a much larger area then a disk shaped one and would lead to excessive payload penalties.

It's harder to make a simple spherical section design self-righing then it is a biconic, as you have less area in which you can put your center of mass, but not impossible.  One way to achive this would be to focus the shield (and center of mass) to one side of the vehicle, so that the engines come down mainly facing on their side relative to the atmosphere.  In any case, the tank can be redesigned to accomidate a larger biconic heat-shield, this may be necessary in any case.  The trailing edges of a biconic heat shield need not be as heavy either as they face less of the heat load.

"As I said before, I think the CEV with all it's components masses considerably more than you think it does, the pod would certianly mass less then half of the 22MT the CEV does, (minus the engines). The parachutes and airbags would have to be scaled up for recovery, but this is haredly a daunting design issue. As for the rest of it systems, it should be obvious how much simpler the pod is versus the CEV"

I was referring to the capsule only and not the whole vehicle, and it seems I have confused the masses of the capsule and the service module. No matter... the SSMEs will weigh 16MT by themselves, and their support hardware several more tonnes, which is adding up to be a pretty hefty capsule, especially if it has a biconic heat shield. 10-15MT+ perhaps not counting the SSMEs and their hardware. I have doubts that the landing systems could be scaled up sufficently without difficulty, and the payload penalty will be fairly large.

Again, using the larger tank can more thank make-up for this payload penalty, as could an up-rated secound stage (which we probably want to do eventualy anyways).  Scaling the recovery system will be good practice anyways as we eventualy want to deploy such systems (or very similar systems) on Mars.

Anyway, I strongly disagree that the pod will be simpler then the CEV capsule, the support hardware required for five SSMEs will be of similar complexity to the power/LSS of CEV, and the fuel line/structural heat shield penitrations required add substantial complexity to the design too. And it will also probably need attitude control too. It will not be any simpler then the CEV capsule.

But realy, the pod is not that diffrent from the disposable RS-68 design in terms of it's requirments.  It has a heat-shield and a recovery system, but otherwise they are functionaly identical.  It's power system needs to last only marginaly longer, it's avonics and control needs are virtualy the same.  Gimbles and the like are identical.  And with the proper design of it's heat-shield no atitude control is necessary as it will naturaly fall in the proper orientation (and if it DOESN'T naturaly fall in the proper orientation no attitude control system will likely be enough to allow it survive re-entery).

---

While I don't believe that NASA would ever outright be closed down, I don't think that a future any of us except Jeff Bell wants is a sure thing. Texas and Florida don't care where NASA flies to, as long as they keep flying. It is quite possible that NASA will be restricted to "science" missions in LEO for a long long time if they fail to make credible progress with VSE on time and on budget.

Without manned space-flight there is no reason for the Kennedy or Johnson Space Centers, at least not at their current levels.  I doubt there is anything the senators/congresspersons from Texas or Florida would take in trade for shutting down these multi-billion dollar parts of their economies.  I just don't share your doubt that manned space-flight is in danger.

I am also skeptical about NASA's budget being raised as the economy strengthens, or at the least the portion of NASA's budget that is available to spend on launch vehicles will not differ greatly. If NASA is told to do something in addition to the VSE plan, then it will probably be an expensive something and they may not get much extra money to spend on launch vehicles. Also, if it seems to congress that NASA is doing okay with VSE on $16.5Bn a year, why would congress give them lots more money?

Two simple reasons. 
#1.  Historicaly this has been true.  Nasa's budget for space-flight manned and un-manned has been increasing over time in real dollars.
#2.  Nasa is a bureaucracy and the nature of bureaucracy is to expand over time.  This is as inevitable as the expansion of our goverment in general is.  In fact is actualy a subtule plan for budget expansions as an actual moon base and missions to Mars will require more money then is currently budgeted.

What determines the worth of the engine pod is how much it saves per flight and how many times it will launched: how many times is NASA going to fly the CaLV? Assuming NASA goes through with the ESAS plan and something like DRM-III for Mars then each Lunar mission will expend one and each Mars vehicle will take two with three vehicle required per mission. To man bases on either body continuously, two Lunar sorties per year and one Mars sortie every other year would be required. To build/tend a base, lets increase the demand by one additional sortie per year to the Moon and one every year other to Mars.

Lets say that it will take 40 years from now to execute the VSE plan and build both bases; assuming we operate a Lunar base concurrently with a Mars base and Mars missions start 20 years from now, that will mean we will need 164 copies of CaLV (24 from now to 2026, 140 from 2026 to 2046). In the event that we want to keep using CaLV longer then 2046 this figure could be higher, or if Lunar crew/cargo were farmed out to private interests and the DRM-III plan made semi-reuseable it could be lower (use ERV as cycler, build reuseable Mars-fueled MAV).

I think a range of +/- 35 units is really the edge of reason. An extra 35 units would take us to 2051, at this point NASA's budget should be pretty heavily strained just maintaining both bases, and they won't have enough money to do alot else. I think this is end of the line for the CaLV, and either a much less expensive rocket would be built from scratch with then-new technology, or a true RLV built.

Reuseing my cost figures from my last post, with $10Bn for development and construction of the pod, and for reference NASA's total budget is $660Bn over 40yrs at $16.5Bn/yr.

-Best case senario, SSME pod replaces $75M of RS-68 engines, $25M of support hardware, and $25M to widen the tank for a total of $125M saved.

-Worst case senario, bulk orders of RS-68 reduced to $60M a flight and essentially no savings on reusing support hardware due to refurbishing costs, saving $85M a flight.

129 flights - best $6.0Bn, worst $1.0Bn
164 flights - best $10.5Bn, worst $4.0Bn
199 flights - best $15.0Bn, worst $7.0Bn

So if everything went really well, NASA would save $15Bn over a very long time, but if it doesn't go well NASA will only save a few billion at most... Also, this savings will only be realized as small annual sums over many years, and not as a big lump sum over a few years needed for a development program or even an additional Mars mission, but if only a few billion is saved as in "worst case" then this savings will be impreceptable.

I believe there is also a risk that congress, seeing this "extra money" going unused, will simply take this money and spend it on something else, or perhaps the non-VSE wings of NASA will sucessfully lobby for a small annual raise. NASA is not a bank, and its ability to store up cash is limited by external and internal political realities.

I agree with most of your reasoning here, but not with your conclusions.  It's very hard for me to understand people arguing that saving money is a bad thing.  If we want to waste money, we could keep the shuttle going for heavens sake.  Heck an ISS style Moon or Mars mission might be possible if we realy want to.  It's this kind of reasoning that got us stuck in our current rut.  Without continuing efforts to lower the cost of space-travel we will end up doing nothing.

I never argued that we should somehow "save" the extra money in bank someplace, maybe "saved money" is a bad choice of phrase if it leads you to thinking down this path.  What would instead happen is that NASA would have to spend less on the VSE and could spend more (or lobby for more money more succesfully) to spend on other productive endevors.  Ann odd phenomenon that you sometimes see in buisness and goverment is that more money is more happily thrown at ecnomical and sucessful programs then those that are more wasteful.  In any case, the goverment at large rarely wades into an itemised report of spending and so will most likley vote for a yearly NASA raise based upon the acomplishements of the space-program, and nothing else.

Back to topic of can we and should we forgo the cost to develope a reusable engine pod. Knowing that it will land in water means a total teardown after each use. The shuttles engine do not land in water and they still are under a million to refurb. Have posted this 96 shuttle reference before in that it breaks down which facility gets what with this regards.

As I said before, the pod will likely be recovered over land not see, and so corrosion due to sea-water and a the expense of a recovery fleet are not necessary.

---------

A side note on the economics in general, think about the long term alternatives to the CaLV for HLLV?

#1. Space Elevator - This would be the best, but it may never be technicaly possible.  The start-up costs and time are bound to be huge even if it is possible (though I would agree that there are worth-while).

#2. Totaly Cheaply Reusable Launch Vehicle - SSTO or TSTO HTHL style - Still incredibly technicaly difficult to impossible.  And even if one of these is made, it is not very likely going to be in the 100MT range.  If we are lucky maybe 20MT or so.  Still leaving a place for the CaLV

#3. Clean Sheet HLLV, totaly or partialy reusable - the only solution we can count on being able to design.  The question is, could we improve upon the CaLV especialy, the CaLV/Pod design?
- The CaLV/Pod already mounts engines at the bleeding edge of performance, reusability, and relability, the SSME.  Unless some dramatic new fuel type is introduced, it is unlikely that a new engine type could be designed that has a drasticaly higher ISP than the SSME combined with being cheaper to reuse and safer.  The only area it could be improved upon is thrust, which really isn't that necessary.
- SRB are pretty cost efficent, but the CaLV could replace these with RS-84 Powered flyback boosters for even more juice and lower cost.
- Fuel Tanks are large and hard to recover no matter what you do.  I have a hard time imagning a re-usable tank that does as much as our current ET, with diffrent staging options you might though
- The EDT is currently totaly no-reusable, so there is room for improvment

Basicaly, when I look at the alternatices, the CaLV with upgrades looks pretty good.  It's hard for me to imagine how we could do better for large 100MT payloads than it in any new design, though I am open to suggestions.


He who refuses to do arithmetic is doomed to talk nonsense.

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#28 2006-05-21 16:49:47

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 21,678

Re: Engine Pod Economics

I never argued that we should somehow "save" the extra money in bank someplace, maybe "saved money" is a bad choice of phrase if it leads you to thinking down this path. What would instead happen is that NASA would have to spend less on the VSE and could spend more (or lobby for more money more succesfully) to spend on other productive endevors.

The trouble is congress directs how much money Nasa gets and seeing it can operate with less would mean that they would simply budget less money for Nasa to use...

SRB are pretty cost efficent, but the CaLV could replace these with RS-84 Powered flyback boosters for even more juice and lower cost.

Sure would be nice but the engine was a cancelled project of OSP or was it the SLI.

Back to topic of can we and should we forgo the cost to develope a reusable engine pod. Knowing that it will land in water means a total teardown after each use. The shuttles engine do not land in water and they still are under a million to refurb. Have posted this 96 shuttle reference before in that it breaks down which facility gets what with this regards.

As I said before, the pod will likely be recovered over land not see, and so corrosion due to sea-water and a the expense of a recovery fleet are not necessary.

If you are thinking a snatch and grap as in stardust its weight would make this not possible. If the soyuz style landing of clunk and bang would mean more weight to be added. TPS tiles would be better for weight but means now a landing bay door to seal as in the shuttles case for a runway landing.

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#29 2006-05-21 22:03:32

Martin_Tristar
Member
From: Earth, Region : Australia
Registered: 2004-12-07
Posts: 305

Re: Engine Pod Economics

If I was going to purchase launch vehicles for space and that I throw away 75-80% of the vehicle after one launch then that's crazy.  That means if a launch costs $200M then I would lose $150-160M and couldn't recycle that in space or on earth under the current launch methods. No wonder the government are the main customer for launches.

Why develop reusable engines like the space shuttle main engines (SSME) or RS-68 engines, If we don't reuse the engine assemblies / engine pods in other vehicles including unmanned automated vehicles for the advancement of space.

If we developed any other industries on an "once use" policy including the transport or communications or mining or any other industrial sector across the world, you would not get any funding from private industry without the use of government funds. So, when you look at the Space Industry in United States that is the government funded / backed industry , It doesn't function without those funds thus its a bankrupt sector getting held up by government money.

The only way to develop new technology it must be practicable and reusable in the long term viability for the space sector. That means we need to reduce launch costs and make the vehicles once in orbit easy to broken down in orbit and any parts in earth atomsphere be recoverable and reused in future launches.

I am being blunt about the future of the industry sector because " Handouts " can only sustain but doesn't expand the sector only Innovation and planning for the future of permanent human settlement in space.

8)

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#30 2006-05-21 22:15:05

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

Re: Engine Pod Economics

GCNR, Mr Money Bags !!!!!!!!

If we don't recycle and build vessels including drone / automated vehicles with recycled or reused components from previous launches then it will cost more money and resources then any one country has to offer and could afford. The first spacefaring nation or organization that develops their space program on a large recycle program will win the space race even on a smaller budget.

So, Mr Money Bags, If you want to get charged for parts that can be reused including the engines particular they could be reused in space then we should look at those proposals. Also we have the technology ( both Hardware and software ) to launch and build a moonbase or marsbase with automated vehicles using gaming methodology and rule based logic systems. I think you don't see all the advances in technology at the hardware and software platforms that could be adapted to the space environment and function nicely.

I do think we could use automated systems to setup a small outpost landing for humans to arrive on Mars and could have the gardens and other systems running before any humans have landed and when the humans land the environment is set for life. So , think before you type, Mr Money Bags. (AKA GCNRevenger)

A fairy tale, recycling the fairly small spent upper stages and their engines is stupid, a little cheap metal and small rocket engines are never going to be worth as much as it will cost to reuse them.

And psuedo-intelligent robots to build bases? Please, robots thus far can't even roll up/down slopes without careful planning and human hand-holding by remote.


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

The glass is at 50% of capacity

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#31 2006-05-22 06:17:04

Grypd
Member
From: Scotland, Europe
Registered: 2004-06-07
Posts: 1,867

Re: Engine Pod Economics

Jeff Bell can I say any more has his view on the VSE and its engine and design selection.

The VSE Booster Switch


Chan eil mi aig a bheil ùidh ann an gleidheadh an status quo; Tha mi airson cur às e.

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#32 2006-05-22 07:28:50

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 21,678

Re: Engine Pod Economics

Some numbers on the developement costs, payload to orbit and Liquid flyback boosters.

Shuttle C. orbiter replaced by recoverable pod with shuttle main engines and payload cannister. Quick way for US to obtain heavy payload capability and reduce shuttle cost per kg to orbit by 3 X.


Manufacturer: NASA. LEO Payload: 77,000 kg. to: 400 km Orbit. at: 28.0 degrees. Liftoff Thrust: 2,069,940 kgf. Liftoff Thrust: 20,299.20 kN. Total Mass: 1,966,675 kg. Core Diameter: 8.70 m. Total Length: 56.00 m. Flyaway Unit Cost $: 84.97 million. in 1985 unit dollars.


Boeing's version of The engine pod would be recovered or integral and separable engine pod variations were explored, resulting in payloads between 59,000 kg and 91,000 kg. A three-SSME version could but 91,000 kg into orbit and would have a gross liftoff mass of 922,000 kg. A four SSME version could put 102,000 kg into orbit with a gross liftoff mass of 975,000 kg. The propulsion module was to be designed for 300 flights. Development cost was estimated at $930 million, and first article cost for the engine pod $135 million. Cost of expendable items per flight was estimated at $4.23 million, with total cost per flight $14.136 million, or $1118 per kg to orbit, as opposed to the $1323/kg expected for the basic shuttle at that time.


[url=http://www.astronautix.com/lvs/shulelrb.htm[/url]Liquid Rocket Boosters[/url]

Stage Number: 0. 2 x Shuttle LRB Gross Mass: 350,000 kg. Empty Mass: 52,000 kg. Thrust (vac): 1,052,154 kgf. Isp: 435 sec. Burn time: 121 sec. Isp(sl): 330 sec. Diameter: 5.50 m. Span: 5.50 m. Length: 45.54 m. Propellants: Lox/LH2 No Engines: 4. STME

Liftoff Thrust: 2,152,360 kgf. Liftoff Thrust: 21,107.40 kN. Total Mass: 1,575,493 kg. Core Diameter: 8.70 m. Total Length: 56.00 m. Development Cost $: 1,629.00 million. in 1985 average dollars.

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#33 2006-05-22 13:24:23

Austin Stanley
Member
From: Texarkana, TX
Registered: 2002-03-18
Posts: 519
Website

Re: Engine Pod Economics

The trouble is congress directs how much money Nasa gets and seeing it can operate with less would mean that they would simply budget less money for Nasa to use...

This is a poor argument against saving money, even if it was true.  NASA and the US Goverment at large would be better off not wasting money if they could avoid it, even if this means NASA wouldn't get to spend the saved money.  Wasting money is simply bad, no matter how you cut it.

But I don't belive this argument is true.  NASA's funding as a percentage of the US budget is probably most strongly influenced by public support for it.  As this is likely to remain constant or increase with a succesfull, thrifity, space program the percentage of the US budget that NASA gets will stay stable or increase.  Which means the real dollars they get will expand as the US economy and Goverment budget expands.

It is true that the Goverment is often guilty of throwing good money after bad (shuttle, ISS, Iraq), but it is even more true that successful, cost effective program is even more likely to get more money with less debate.  There are exceptions, of course, but certianly this is the ideal we should strive for.  Going with a less succesfull program instead of a more successful program in order to ensure goverment fuding is lunacy, AND it is exactly the same line of reasoning that got us the Space Shuttle and ISS.

Sure would be nice but the engine was a cancelled project of OSP or was it the SLI.

This is more of a tangental point.  I was just pointing out that developing the proposed liquid fueld fly-back boosters is another logical improvment upon the CaLV.  The SRB cost something like $15 million to refurbish and $50 million for new copies, so there is money to be saved here.  And they could improve performance.

If you are thinking a snatch and grap as in stardust its weight would make this not possible. If the soyuz style landing of clunk and bang would mean more weight to be added. TPS tiles would be better for weight but means now a landing bay door to seal as in the shuttles case for a runway landing.

I was thinking more along the lines of parachutes and air-bags, ala the CEV, but I am open to any option that works.  Maybe a parasail and a runway landing, or a retro rocket instead of air-bags.  Recovery of such a large object will be good practice for our Mars Mission as well.

-----

Shuttle C. orbiter replaced by recoverable pod with shuttle main engines and payload cannister. Quick way for US to obtain heavy payload capability and reduce shuttle cost per kg to orbit by 3 X.

Manufacturer: NASA. LEO Payload: 77,000 kg. to: 400 km Orbit. at: 28.0 degrees. Liftoff Thrust: 2,069,940 kgf. Liftoff Thrust: 20,299.20 kN. Total Mass: 1,966,675 kg. Core Diameter: 8.70 m. Total Length: 56.00 m. Flyaway Unit Cost $: 84.97 million. in 1985 unit dollars.

Compares not so favorably with my estimates.  The CaLV has ~65% more deliverable mass.  In 2004 dollars its price is some $236 million (by the most pesimistic measures).  Pretty high, but this includes both the SRB, payload capsule,  and ET in it's estimate, which mine does not (since both versions of the CaLV have to pay for that).

Boeing's version of The engine pod would be recovered or integral and separable engine pod variations were explored, resulting in payloads between 59,000 kg and 91,000 kg. A three-SSME version could but 91,000 kg into orbit and would have a gross liftoff mass of 922,000 kg. A four SSME version could put 102,000 kg into orbit with a gross liftoff mass of 975,000 kg. The propulsion module was to be designed for 300 flights. Development cost was estimated at $930 million, and first article cost for the engine pod $135 million. Cost of expendable items per flight was estimated at $4.23 million, with total cost per flight $14.136 million, or $1118 per kg to orbit, as opposed to the $1323/kg expected for the basic shuttle at that time.

Estimate compares favorably to mine.  The development costs are WAY lower than mine.  By the most pesemistic estimate those 1977 dollars are worth ~5 Billion in 2004 dollars, and thats for developing a much large more ambitious vessle then the pod I propose.  The cost per flight is not so favorable, but it likely also includes a great deal of hardware that the pod estimate doesn't include, like SRB, ET and various other disposable items.  The Class II versions figures come in pretty much in line with what I estimated.


He who refuses to do arithmetic is doomed to talk nonsense.

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#34 2006-05-22 14:15:21

Admiral_Ritt
Member
From: Imperial Capital of the Pacifi
Registered: 2005-03-09
Posts: 64

Re: Engine Pod Economics

Actually the first nation to able to get a launch vehicle to 2 mi/Sec
before engaging it's own engines will win the space lottery.

Which way would have been more efficient launch vehicle

1) Sled Launched into & out of a deep valley?

2) Carrier Jet/rocket hybrid

These two methods plus an equatorial launch latitude would
come close to halving the actual launch vehicle fuel/mass requirements for
orbital flights.   Unfortunatetly Many of the semi-moutainous equatorial areas
of the world are either too Seizmically unstable or  Politically Unstable, more's
the pity.

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#35 2006-05-22 21:00:40

MarsDog
Member
From: vancouver canada
Registered: 2004-03-24
Posts: 852

Re: Engine Pod Economics

 
Design a reuseable booster:
Beamed power, multiple stages, ending with a chemical rocket for last stage.

Sled Launched, ramp to space is possible, but expensive and long time to build.
 

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#36 2006-05-24 09:44:49

Jack Chandley
Member
From: Rhode Island
Registered: 2006-05-22
Posts: 14

Re: Engine Pod Economics

Engines do not like landing in the ocean and will add to the cost depending on how long they are in the water before recovery occurs.


I'd like to add to this.  Not only would you have a ater landing, but a salt-water landing.  You would then be introducing galvanic corrosion along with all the inherent (if applicable) damage to the electrical system.

If you alternately chose to do a parachute landing to a land location, even if one could devise a softer landing method, there are still some nasty side effects associated with the shock of the landing.

The SSMEs are less expensive to refurb due to a nice, controlled, soft landing with little exposure to the unsavory elements of shock and/or saltwater.

Not trying to discourage you, just pointing out a few challenges.


Sure people dream about space travel.  There's nothing wrong with that.  Everything humankind has made, was once but a dream.

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#37 2006-05-26 18:42:49

RedStreak
Member
From: Illinois
Registered: 2006-05-12
Posts: 541

Re: Engine Pod Economics

Reuseability is a nice option but at our stage its obviously why the shuttle proved to be a nightmare - that and fact it was built on too many compromises.

Engine pods are out of the question.  The new 5-segment SRVs will be enough to tweak; if they can manage to reuse them that's more than enough for the CaLV and the CLV for that matter.  The CEV crew capsule could potentially be reused too, but beyond that reusability is too much of a headache when the main focus is just getting something up to the moon or beyond.

Do it in small, manageable bits.  I don't want to see another Challenger or Columbia bursting into flames because of too many compromises again.  sad

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#38 2006-05-26 18:54:51

RedStreak
Member
From: Illinois
Registered: 2006-05-12
Posts: 541

Re: Engine Pod Economics

Engines do not like landing in the ocean and will add to the cost depending on how long they are in the water before recovery occurs.


I'd like to add to this.  Not only would you have a ater landing, but a salt-water landing.  You would then be introducing galvanic corrosion along with all the inherent (if applicable) damage to the electrical system.

No offense, but logically if the capsule is air-tight how the heck can water get inside to even do any damage?

I can see how this'll be a problem for an engine pod, and I doubt there's anyway to get it to float engines-up.

Galvanic corrrosion?  Will that be an issue for the CEV if it needs to make a sea-landing?

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#39 2006-05-31 07:19:31

Jack Chandley
Member
From: Rhode Island
Registered: 2006-05-22
Posts: 14

Re: Engine Pod Economics

Engines do not like landing in the ocean and will add to the cost depending on how long they are in the water before recovery occurs.


I'd like to add to this.  Not only would you have a water landing, but a salt-water landing.  You would then be introducing galvanic corrosion along with all the inherent (if applicable) damage to the electrical system.

1] No offense, but logically if the capsule is air-tight how the heck can water get inside to even do any damage?

2] I can see how this'll be a problem for an engine pod, and I doubt there's anyway to get it to float engines-up.

3] Galvanic corrrosion?  Will that be an issue for the CEV if it needs to make a sea-landing?

I numbered the items in your post to address which comment is applicable.

1] Capsule?  Are you talking CEV or the proposed reuseable engine pod?  For the CEV, I doubt there would be a great deal of issue.  However, this thread, and my comments were regarding an engine assembly, and that would be something else, entirely.  An engine pod requires significant openings.  A capsule requires minimal openings.  To devise a method to have an automated way to enclose an engine pod in an extendable heat shield does not sound practical-too many moving parts.  Please advise if otherwise.

2] Concur. No doubt it is possible, but not practical.

3] Galvanic corosion would again be an issue for the engines.  The CEV, "not-so-much". There will need refurb on the CEV between flights, and I assure you (in the case you are not personally familiar with it) that saltwater is a nasty substance to protect from.  (In case you are wondering, I deal with satellite communication systems for nuclear submarines)

Unless the engines have every metal component made from exactly the same alloy (and I'm taking a leap here, and am assuming this is not the case), then a saltwater landing is a big refurb challenge.  The galvanic corrosion always attacks the least noble metal first.  Of course, there is one simple, but rather unelegant solution: place a few sacrifical anodes (zincs) on the engine.  It'll buy time, and could limit the corrosion damage.  The downside is the added weight & how to make it heat resistant from launch and re-entry.


Sure people dream about space travel.  There's nothing wrong with that.  Everything humankind has made, was once but a dream.

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#40 2006-06-02 17:18:56

Austin Stanley
Member
From: Texarkana, TX
Registered: 2002-03-18
Posts: 519
Website

Re: Engine Pod Economics

All good points, but this is again why the engine pod would be recovered over land, the same way the CEV is (with air-bags and parachutes).  This eliminates the problems with sea-water corosion and eliminates the expense of a recovery fleet.


He who refuses to do arithmetic is doomed to talk nonsense.

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#41 2006-06-05 04:35:20

MarsDog
Member
From: vancouver canada
Registered: 2004-03-24
Posts: 852

Re: Engine Pod Economics

 
Recycling is $$$ driven.
Drive a new car and soon the value is considerably less.
Each time it is repaired, you recycle it to yourself.
Eventually it becomes scrap metal value.

The only reuseable spacecraft is the space shuttle.
The concept did not turn out as well as intended.
Perhaps, need larger numbers before the design is perfected.
 

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#42 2006-06-09 11:14:42

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

Re: Engine Pod Economics

Enough with the re-usability crap. Build big and simple. A recoverable engine module will just add to costs.

HLLV--not HLV is what we need.

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