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Possible Craft

Posted by: Sev - Sun Oct 10, 2004 4:10 pm
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Possible Craft 
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Post    Posted on: Fri Oct 22, 2004 1:31 pm
Ekkehard Augustin wrote:
Might it be possible that the vehicle could rescue the upper stage or its engine some way?


There are three basic problems with reusable upper stages:

1. By the time the upper stage has run out of fuel, it's in orbit. Force must be applied to it in order for it to re-enter (i.e. it has to 'save' some fuel to fire a retrograde burn).

2. The velocity of the craft has increased to the point that it will burn up on re-entry. Adding heat-shielding to *keep* it from burning up on re-entry is weight-prohibitive.

3. If you solve the above two issues and the upper stage is coming down to earth -- you have to control its landing somehow.

The only way to avoid an expendable upper stage is either an SSTO or a TSTO. Either of these require revolutionary new technologies that are almost assuredly beyond the reach of a $50 million contest.


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Post    Posted on: Fri Oct 22, 2004 1:57 pm
Yes, I know.

I look at the problem from the manned vehicle designed to reach Nautilus. If the vehicle could rescue the upper stage this stage could be connected to Nautilus some way. I know - that's not part of any concept right now but it might be possible if the existing concept is modified a little bit.

Supposed the upper stage would be rescued and brought to Nautilus. Then it could be left there first. Then there rae several options: 1. making it an integral part of the space station if it becomes growing, 2. making it a never landing spacecraft, 3. using it as a source of material for repairs, 4. slowly and slightly modifying it for reentry.

Next the vehicle docking to Nautilus has to reentry and do a controled landing as well as the upper stage would have...

The rule is said to be 80% reusability - allright, this is not set down in black and white yet, but it might be perhaps. So if this set down in black and white then I suppose that the vehicle has the greater percentage and this would mean that it has to be reusable. Again this means the winner of the America's Space Prize would be able to build an upper stage that is reusable.

But I'm doubting a little bit wether the upper stage reaches orbital velocity and needs a burn for reentry. It accelerates its payload to orbital velocity but which way then does the payload leave the stage? Then orbital velocity of the stage seems not to be required. Or by control engines or is the stage opened and the decelerated a little bit? In this case it wouldn't have rbital velocity at the end of its mission and reenter.

If the stage is rescued and brought to Nautilus only then for JP Aerospace's vehicles and infrastructure could be waited - I suppose their concept is providing a safe and secure way to bring the stage back to earth.



And we should have in mind what leaving the stages in orbit would mean: orbital tourism would cause a significant increase of the amount of orbital debris which would increase the danger of damages by colliding to one of all the private upper stages.



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Post    Posted on: Fri Oct 22, 2004 3:27 pm
If you can save the upper stage. A very big if. The upper stage will probably be at a lower orbital than the proposed station for one and rapid orbital decay is likely to happen due to its lower orbit.

It is unlikely that you could refurbish the upper stage in space, even with a space station available. Too much work involved and you can't be forever refurbishing used upper stages.

Just let Sir Isaac Newton do his job.


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Post    Posted on: Fri Oct 22, 2004 5:50 pm
Ekkehard Augustin wrote:
Supposed the upper stage would be rescued and brought to Nautilus. Then it could be left there first. Then there rae several options: 1. making it an integral part of the space station if it becomes growing, 2. making it a never landing spacecraft, 3. using it as a source of material for repairs, 4. slowly and slightly modifying it for reentry.


1. Attaching a spent upper booster to a space station as an 'addition' is akin to cleaning off the paper plates and plastic cups from a picnic and putting them in your china cabinet along with your fine dinnerware and crystal. They're made to last *just* long enough to get to orbit. There's nothing in them to make them useful to the station.

2. It's a big hollow shell. It's not a spacecraft and can't be modified into one while in orbit. Here's a science project for you -- take a trash can -- throw it in the nearest lake, then get some scuba gear, and modify that trash can into a submarine while working underwater.

3. There's no machine shop in orbit and won't be for some time. The expended booster won't simply break itself up and deliver ready-to-use building matrials to the airlock.

4. There's still no machine shop -- plus how do you see modifying an empty shell to add heat shielding, guidance systems, and propellant such that it can make a controlled re-entry?

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The rule is said to be 80% reusability - allright, this is not set down in black and white yet, but it might be perhaps. So if this set down in black and white ...


If the rule is 80% reusability -- *and* this includes the spacecraft *and* the launch system, *and* no qualifications are given, then the prize will not be won. Probably no company will even get to the stage of making hardware.

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But I'm doubting a little bit wether the upper stage reaches orbital velocity and needs a burn for reentry.


The upper stage does not get any significant retrograde velocity when the separation charges split it from the spacecraft. Will it re-enter atmosphere at some point? Of course -- just as anything below about 1000km will. However -- a re-entry that is based on nothing more that atmospheric friction is completely uncontrolled -- there is no telling when -- or where it will re-enter. It's useless in terms of recovering the stage. There *must* be the ability to determine when and where the stage will re-enter if it is to be recovered. This means that it must have the ability to provide controlled retrograde thrust.

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And we should have in mind what leaving the stages in orbit would mean: orbital tourism would cause a significant increase of the amount of orbital debris


As per the above -- the orbit would decay through atmospheric friction.
Rules of thumb on orbital decay are:

At 100km your orbit lasts about an hour.
At 150km your orbit lasts about a day.
At 200km your orbit lasts about a week.
At 250km your orbit lasts about a month.
At 300km your orbit lasts about a quarter.
At 350km your orbit lasts a bit under a year.


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Post    Posted on: Fri Oct 22, 2004 7:37 pm
An additional entry for Sev's excellent table :)

Code:
Launcher      Payload  Cost($US) kg/$M  Margin
----------------------------------------------
Falcon V      6,200     13       476     1.00
Kistler K-1   5,700     17       335     1.42
Soyuz         7,000     35       200     2.38
Ariane 44L    4,900    100        49     9.77
Atlas V 521   6,000     95        63     7.55
Delva IVM+    6,120    100        61     7.80


The difference is that the K-1 *might* actually be able to achieve the 80% reusability threshold (assuming it ever flies...).


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Post    Posted on: Sat Oct 23, 2004 9:05 am
mrmorris wrote:
1. Attaching a spent upper booster to a space station as an 'addition' is akin to cleaning off the paper plates and plastic cups from a picnic and putting them in your china cabinet along with your fine dinnerware and crystal. They're made to last *just* long enough to get to orbit. There's nothing in them to make them useful to the station.


Interorbital seem to think they can do it. They have stated that the upper stage tankage of the Neptune OLV will be converted into habitat volume while on orbit. Exactly how they plan to do that is still a puzzle. :?


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Post    Posted on: Sat Oct 23, 2004 3:11 pm
There is also another question that occured to me. The offer that a contract will be awarded to the winner of the prize.

The winner of the prize might not be the most effective vehicle, both cost and design wise. As suggested, a team could design a very basic capsule design that could be launched onboard the SpaceX or any other commercial launcher and there could be another team with a SSTO design. The first team clearly has the advantage of having less engineering risk, while the second team would have a longer, more protracted development but a potentially more cost effective design on the long run.

I hope the prize will address this.


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Post Re: Possible Craft   Posted on: Sat Oct 23, 2004 7:36 pm
DerekL wrote:
Sev wrote:
There are currently two "reusable" launch vehicles, the SpaceX Falcon series, and Space Shuttle.


That's not quite correct. There is one "reuseable" vehicle, the Space Shuttle. The Falcon has yet to fly in any form and its final costs and capabilities are far from known.


Pardon me, but no vehicle which needs to have nearly all of the wiring and each tire replace for each flight counts as reusable, much less one that throws away a quarter of its dry mass (the SRBs) to float in the Atlantic (which then have to be completely and totally stripped down and rebuilt), and over half its volume to burn up in the atmosphere. Not to mention the 31,000 hand-applied, custom-machined heat tiles.

The Space Shuttle is the single worst failure of Aerospace Engineering in history, and is certainly not a "reusable" SSTO launch vehicle.

-- spacecowboy

P.S. -- Yes, I did note the quotes on "reusable". This was mostly for the benefit of those who think that the Shuttle actually has some positive design features. It doesn't.

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Post    Posted on: Sun Oct 24, 2004 5:26 pm
Hello, mrmorris,

as well as Bigelow is working on a private space station as an orbital hotel for tourists and astronauts another entrepreneur may decide to work on an orbital machine shop in the nearby future.

Remember that Interorbital plans to service satellites by their vehicles - refuelling, repair and the like. If they succeed in this they may be able to construct and install a macine shop too.

The machine shop don't need to be there NOW - it would be sufficient if it is there in ten or twenty years or so. My proposals 2, 3 and 4 are designed under perspectives like this - long term. It might be useful and advantageous for all space travellers to get control of the stages while they are in space. That means to collect them and store them at one certain well known place - t a spce station would be the best. And that could be assisted by a stage as integral part of Nautilus.

And during the decades orbital space tourism might expand to orbits of 1000 km and higher.

Under short term considerations (5 years) you are right - but that wasn't my perspective.

And JP Aerospace will be able to rescue stages at lower orbits than Nautilus will be installed.



Dipl.-Volkswirt (bdvb) Augustin (Political Economist)


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Post    Posted on: Sun Oct 24, 2004 10:09 pm
Hmm, right, time to clear up some things :)

As far as I know, there is no resuability requirement for the Bigelow prize, or at least not yet. That said, very little about the prize has been said yet.

Continuing that note, I think it is extremely unlikely (so much so that I would say quite blankly - it's never going to happen) that SpaceX makes the top stage of their launch vehicles reusable. Any such system is going to mean it has to survive full orbital re-entry, which quite frankly would at least double the cost of the entire vehicle, and probably much more. They're there to make money in the commercial launch business, not mess about with prizes, so it isn't going to happen. They would be more than obliged to provide a launch service for people, but they're not going to spend vast sums of money just to help someone win a prize. Personally, I doubt it will matter anyway. Anyway, the dry mass of an upper stage is quite small anyway, so it probably wouldn't affect anything.

To take a brief note about the Space Shuttle, not only does it require huge amounts of maintainance, but it is (once you have removed the government subsidies), ridiculously expensive. I believe each mission costs something on the order of $500M, which puts it about 5 times more expensive than the worst of the other competative launch vehicles, so more in line with 40-50 times more expensive than the Falcon.

To go back to the original topic, I don't believe there is any doubt that it would be possible to re-build a gemini clone and get it launched, all you need is the team to do it, the money to back it, and the prize to actually be announced.

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Post    Posted on: Mon Oct 25, 2004 7:21 am
Concerning the Shuttle my informations say that one launch costs 1,2 billion dollars.

Reusability of upper stages includes the question what reusability really is or means. Most of the posts considering reusability are based on the assumption that reusability really allways means or includes the ability to reenter safe of its own. Other posts are assuming that it means the requirement of braking rockets and the like.

Reentering safe of its own or braking rockets are methods - but not the only ones. JP Aerospace's vehicle will launch at 42 km altitude and go to orbit by an ion drive. It will take several days to reach the orbit. It will decelerate and reenter by the same technique I suppose. So it might take a stage and carry it to the atmospheric station JP Aerospace will provide at 42 ikm altitude. This is an additional way or method - the stage would return safe by assistance of another vehicle. It might be refueled and do service again.

A fourth method may be the Robert Wingley's idea of a particle beam for acceleration a spacecraft to 11,7 km/s - this beam can be used for deceleration too (and has explicitly to be provide at Mars as the target planet). So it could decelerate stages - but could accelerate suborbital vehicles too up to orbital velocities. What's required then is a sufficient sail added to the stage(s). ... ...

It might be useful to differ autonomous reusability (safe reentry of its own and having braking rockets) - and assisted reusability (reentry by a carrier or external deceleration).



Dipl.-Volkswirt (bdvb) Augustin (Political Economist)

EDIT: The space elevator has to be added as a possible assistant to rescue and reenter a stage, but I suppose that the particle beam is easier to realize than the equipment to rescue a stage by the elevator. And the beam might be there earlier than the elevator.


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Post    Posted on: Mon Oct 25, 2004 1:15 pm
Ekkehard Augustin wrote:
Concerning the Shuttle my informations say that one launch costs 1,2 billion dollars.


Keeps looking better and better doesn't it? :)

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Reentering safe of its own or braking rockets are methods - but not the only ones. JP Aerospace's vehicle will launch at 42 km altitude and go to orbit by an ion drive. It will take several days to reach the orbit. It will decelerate and reenter by the same technique I suppose. So it might take a stage and carry it to the atmospheric station JP Aerospace will provide at 42 ikm altitude. This is an additional way or method - the stage would return safe by assistance of another vehicle. It might be refueled and do service again.


I have always been a sceptic about JPAs plans, personally I doubt they are possible. Then again, they have invested more time investigating the subject than me, but there certainly seem to be some serious flaws in there thinking.

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A fourth method may be the Robert Wingley's idea of a particle beam for acceleration a spacecraft to 11,7 km/s - this beam can be used for deceleration too (and has explicitly to be provide at Mars as the target planet). So it could decelerate stages - but could accelerate suborbital vehicles too up to orbital velocities. What's required then is a sufficient sail added to the stage(s). ... ...


I actually think this would be an almost ideal solution, except for the fact there are a couple of problems that come with this.

Firstly, they don't give you much acceleration (like, 0.1 m/s^2), so slowing down from 8000 meters per second is going to take you a long, long time. This also becomes more of a problem when you consider the fact that when you reduce your velocity, you fall back to Earth - you'd hit the surface before you ever lost much speed. Personally, I still think some form of heat shielding (either solid or abalative) is probably the most effective at this point in time. We can ponder all these possible futuristic solutions, but most of them are pretty far fetched at this stage.

mrmorris wrote:
I've gone much more into detail on possibilities for this concept craft on the SPACE.com forum:

http://uplink.space.com/showflat.php?Ca ... d&sb=5&o=0


Nice post, shame you have to use space.com's boards, I absolutely abhor their message system :)

You know, the original idea was to build a craft with similar specifications and technology levels to Gemini, not necessarily a clone. I did some thinking on this, and there's a couple of interesting ideas you might want to think about:

When reentering, Gemini used to go down blunt-end first, which was where the heat shield was situated. In those days, that made sense, because having a large, flattish heat shield was the easiest to manufacture and place onto the craft, whilst still providing a large amount of drag.

Now adays, with proper non-ablative heat shieldsing, inverting the whole procedure would make sense. Picture a badminton shuttle-cock, which travels with the curved front-end travelling in front of it. If you could heat-shield a similar space (although it would probably cover a large proportion of the space-craft than the rubber bit on a shuttle-cock), it would allow the heat to be evenly dissipated over a larger area, while also allowing it to re-enter in the most aerodynamically stable position. The only other consideration is that the enter of mass would have to be quite far down the nose, otherwise it could possibly flip over.

The other thing you might want to look at is how large the Falcon V's payload fairing is, since any craft would have to be made to fit into that sized space. This could prove more of a problem than the weight in the end.

A final thing I would say is keep the amount of electronics to an absolute minimum, and certainly don't use anything too modern. Modern sub-micron design processors are extremely sensative to radation, and would be useless in space. To be honest, there is a good chance you could run the whole affair without using any digital processors at all, relying only on analogue electonics. This certainly would increase the reliability a great deal.

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Post    Posted on: Mon Oct 25, 2004 1:33 pm
Ekkehard Augustin wrote:
Concerning the Shuttle my informations say that one launch costs 1,2 billion dollars.


The 'launch cost' of a shuttle depends on what accounting method is used. The $1.2 billion figure is generally arrived at by taking the total cost of the shuttle program (employee salaries, infrastructure maintenance, etc.) and dividing that by five launches per year . That's not to say that if a sixth vehicle were launched (assuming it were a year when five made orbiters were launched) that the additional cost to NASA for launch six would be $1.2 billion.

The actual costs associated specifically with a given shuttle launch are closer to Sev's figure -- $300-500 million. (The wide variance is because NASA accounting leaves much to be desired). That said -- the shuttle is extremely expensive no matter *what* accounting method is used.

I might note that a significant part of the reason *why* the shuttle is so expensive is due to the emphasis on re-usability during its design. The shuttle is a prime example of why it's not necessarily a good thing to try so hard to make something re-usable that the end product becomes a nightmare to support. A telling sign that this might be happening is when it's necessary to devise elaborate and costly shemes to find ways of salvaging a couple hundred pounds of aluminum.

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A fourth method may be the Robert Wingley's idea of a particle beam for acceleration a spacecraft to 11,7 km/s - ... So it could decelerate stages - but could accelerate suborbital vehicles too up to orbital velocities.


No. You have no concept of the particle beam propulsion engineering. It's not applicable for orbiting or de-orbiting vehicles. It's a concept for interplanetary spacecraft only. It's only useful in vaccum, and doesn't provide the thrust levels required.


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Post    Posted on: Mon Oct 25, 2004 2:06 pm
You are right concerning the Shuttle. I posted the number 1.2 billion to agree to both you and Sev.

But we shouldn't pay too much attention to the Shuttle's weight and we shouldn't it take too much as an example because it's much heavier and much bigger than a passenger carrier to the orbit will be at a capacity of seven passengers including the pilot - of the whole Shuttle this is the cockpit only!!!

If this spacecraft is used as tourism-vehicle launched once a week at least it would be very economical because of the revenues. Reusability would provide significant advantages from this point of view - the orbital tourism supplier allways has aready vehicle at the site of launch and landing.

If there is no concept of the particle beam propulsion engineering now - can there be one in a couple of years? Why can't it be applied to suborbital spacecrafts that reach altitudes of several hundred or thousand kilometers?



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Post    Posted on: Mon Oct 25, 2004 2:07 pm
Sev wrote:
Now adays, with proper non-ablative heat shieldsing, inverting the whole procedure would make sense. Picture a badminton shuttle-cock, which travels with the curved front-end travelling in front of it. The only other consideration is that the enter of mass would have to be quite far down the nose, otherwise it could possibly flip over.


The only reason a shuttlecock falls the way it does is because of the heavy weight at the tip and the perforations in the 'tail' generate a high-drag (like SS1's tail). The craft in question would have to have a similarly large and high-drag tail for this to work (and the tail itself would have to be heat-shielded, etc.). The traditional capsule shape is so nice because the teardrop shape is aerodynamically stable. Atmospheric friction will orient the capsule automagically with no control surfaces. Any control surface required for the craft adds mass that can't be used for payload.


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The other thing you might want to look at is how large the Falcon V's payload fairing is, since any craft would have to be made to fit into that sized space.


Um -- no. The payload fairing is designed to allow launch customers to place non-aerodynamically shaped cargo (i.e. satellites) inside it to be shielded from the rigors of launching through the atmosphere. The capsule would simply sit atop the second stage -- possibly separated from the stage by an escape tower like the Mercury and Apollo programs to facilitate emergency launch aborts. The capsule has to be of a size to fit on that stage. You wouldn't want it to extend much beyond the diameter of the second stage (if at all), but at 11' in diameter, the Falcon V is already 10% larger than the Titan 2 which launched the original Gemini capsule.


Quote:
A final thing I would say is keep the amount of electronics to an absolute minimum, and certainly don't use anything too modern. Modern sub-micron design processors are extremely sensative to radation, and would be useless in space.


I don't know how much of that thread you went through. In the end -- I agreed on the use of the rad-hardened PC-Card and the VxWorks Real-Time OS. This OS was used on the X-38, and on many current military projects (i.e. figher jets and such).

I disagree about the expense. The more automation that is available to the craft, the better. Ideally it should be able to handle *everything* without pilot input. What is ridiculous is the 99% automation of the shuttle. For example -- the entire shuttle landing is computer controlled except the landing gear. A human must push the button to extend the LG. This is silly. Likewise docking with the ISS. The Russians have had autonomous docking for years, and it's only now that NASA is developing it for the US with the DART program.

It's possible to automate every single aspect of a flight -- from ground, to orbit, to docking, and back to a controlled landing. Every single aspect of this has been demonstrated on vehicles. The Gemini controls were incredibly complicated. This was largely because there *was* no automation. The pilots then had to receive extensive training. A pilot who hit a control out of sequence could easily doom the mission. This is a **much** more likely consequence than a hardened computer making a similar error due to radiation damage. Computer automation will seriously reduce training time for the pilots and will make it easier for them to be cross-trained for other activities (like maintenance on the station).


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