---------- Forwarded message ---------- From: Eric Hunting <erichunt...@gmail.com> Date: Wed, Feb 3, 2010 at 8:43 PM Subject: [luf-team] More Open Source Space To: luf-t...@yahoogroups.com
Looks like the concept of Open Source space programs is starting to snowball.
The unmanned suborbital hybrid rocket seems doable, but that's a long way from an orbital spacecraft and even more from one capable of going to the Moon.
At this time I think it's more important to focus on setting up an automated open source manufacturing base than directly aiming at the Moon.
The costs of spaceflight is not just $$, but mainly work hours of the people working on it. So automising the design and production process, developing OpenSource blueprints for components (turbopumps, valves, etc.) is a prerequisite for any small effort orbital travel.
On 2/4/10, Thomas Fledrich <thfledr...@gmx.de> wrote:
> > Looks like the concept of Open Source space programs is starting to > > snowball.
> > http://cstart.org/ > The unmanned suborbital hybrid rocket seems doable, but that's a long way from > an orbital spacecraft and even more from one capable of going to the Moon.
BTW, has everyone here seen that Analog short story "Openshot," about an OS moon shot project?
I'm one of the founding members of CSTART. One of our other members stumbled across this discussion and pointed it out to the team.
I just wanted to let the interested people here know that a lot of us at CSTART are very interested in talking/working with the Open Manufacturing Network (and other similar communities!) about what we should/can and shouldn't/can't do to best facilitate the low-cost, distributed construction of potentially large physical hardware. We have certainly given this *some* thought, but there has also been a little bit of "magical thinking" along the lines of "if we just make sufficiently detailed plans available under permissive licenses, eventually *someone* will build it!". It looks like your community and others have a lot to teach us about how to improve our chances of success beyond this.
As for the issue of open source blueprints, we are absolutely onboard with this - our Social Contract (see http://cstart.org/wiki/CSTART_Social_Contract) obliges us to (amongst other things) release all blueprints etc. under a CC license.
If anyone wants to talk more about ideas to facilitate the success of an open source space agency, myself and others from CSTART will be very happy to carry on detailed conversations here, on our forums (http://cstart.org/forum/) or via personal email.
> If anyone wants to talk more about ideas to facilitate the success of > an open source space agency, myself and others from CSTART will be > very happy to carry on detailed conversations here, on our forums > (http://cstart.org/forum/) or via personal email.
Since NASA's Moon program has been cancelled now Japans, Europe's and the US's manned government space programs are all behind those of Russia, China and India. I believe this charade that has been going on for several decades now, with each new administration cancelling the programs of the previous one has made it difficult to make any progress with long term stuff and is now even failing to maintain already achieved capabilities. So it's pretty much up to private industry and open source manufacturing if we ever will be able to establish a permanent off world presence. While I wish the national programs of the countries that still seem to be determined to make manned space happen good luck it would still be better if we could pull it off ourselves, optimally without any government involvement.
But it's all a long way off, lot's of work to do. My idea is to begin really small, do what we need to do anyway for everything else in the open source project.
- We need to set up the online blueprint producing and sharing infrastructure. This means upgrading/developing open source CAD programs and an easily accessible database for the blueprints along the lines of wikipedia.
- We need something like Cubespawn as a basic unit,coupled with some kind of robot arm that can automatically assemble the parts produced by it and also exchange worn out pieces.
- Then we can go on to design and build other tools with this assembly and then build more advanced products with these tools.
It is important that everything we do is able to be traced back to that basic unit and that the production process be ideally fully automated.
When designing anything new it should be standard practice to build it yourself first and only add the new blueprints into the online database when it has been proven to work in reality.
I don't know how long this will take and if we can get enough people interested in it but if we manage to get a contributor base of the size wikipedia is today it would completely change the world from the ground up. So it's definitely worth a try.
> Since NASA's Moon program has been cancelled now Japans, Europe's and the US's > manned government space programs are all behind those of Russia, China and > India.
Very true. My money is on China being the next nation to do anything in the field of manned lunar work, most probably a circumlunar flyby in a Shenzhou spcecraft, and on India becoming the 4th nation in space in the near future with their Orbital Vehicle. Russian progress seems a little bit slow at the moment, tied down by uncertain plans to cooperate with Europe. As far as I know Japan have no active manned spaceflight projects at the moment (although they have planned some very interesting stuff in the past, like the Fuji capsule).
> - We need to set up the online blueprint producing and sharing infrastructure. > This means upgrading/developing open source CAD programs and an easily > accessible database for the blueprints along the lines of wikipedia.
There definitely needs to be more open source CAD work done. Earlier drafts of CSTART's Social Contract bound us to only use open source software for design work, but we quickly realised that this would more or less cripple us, as the open source software of the kinds we would need are lagging quite badly behind the proprietary software. The Open Luna Foundation posted about this same problem on Slashdot recently, I think I saw a post about it in this group somewhere. For what it is worth, BRL cad is the most capable seeming open source CAD software that we have found.
> - We need something like Cubespawn as a basic unit,coupled with some kind of > robot arm that can automatically assemble the parts produced by it and also > exchange worn out pieces.
I hadn't heard of Cubespawn before, it looks very interesting, thanks for bringing it up.
One thought on spaceflight which lends itself rather well to this automated assembly line approach is the construction of large launch vehicles by clustering small, simple rockets together. This approach was tried in the 70s by a German company called OTRAG, but it fell through largely for political reasons (the idea seems technically sound). Armadillo Aerospace are looking in this direction for the future orbital vehicle plans, and to the extent that CSTART is interested in building launch vehicles (which varies with our changing assesments of how much of a legal pain it will be (ITAR, etc) and how cheap new generation LVs such as those made by SpaceX are likely to become), we are also very interested in this clustered approach, since it works well for distributed manufacturing (build the individual small rockets all over the world, ship them to one location and then cluster them together).
> I don't know how long this will take and if we can get enough people > interested in it but if we manage to get a contributor base of the size > wikipedia is today it would completely change the world from the ground up. > So it's definitely worth a try.
I would wager we could do incredible things with a much smaller contributor base than that. The team at Copenhagen Suborbitals (http://www.copenhagensuborbitals.com) seem to be doing very well with their one man suborbital microspacecraft project (first unmanned launch scheduled for June or July this year), and their team is just 17 people large (with the vast majority of the work being done by a core team of 2).
> Russian progress seems a little bit slow at the moment, tied down by > uncertain plans to cooperate with Europe.
The main problem the Russians have is similar to the one faced by NASA: Space exploration doesn't provide military superiority, and hence they don't get any money. Of course, even direct military research is getting shafted in the Great Motherland these days, but that's another issue.
> There definitely needs to be more open source CAD work done. [snip] > Armadillo Aerospace are looking in this direction for the future > orbital vehicle plans, and to the extent that CSTART is interested in > building launch vehicles (which varies with our changing assesments > of how much of a legal pain it will be (ITAR, etc) and how cheap new > generation LVs such as those made by SpaceX are likely to become), we > are also very interested in this clustered approach
Not to be a killjoy, but there are some elementary points here. You are talking about designing an orbital launch vehicle, and making the full design, schematics, control electronics and all available to all comers. The applications such a design could - and _would_ - have are rather magnificent. Specifically, any such vehicle could be used to move payloads from one continent to another. There is, incidentally, a special name for a vehicle used for that purpose.
Now, I don't know about you, but I think there are some very powerful folks out there who don't want to have to think about all the implications of that. The way they won't have to think about it is by stopping the project, and once they realise how dangerous the environment it sprang out of genuinely is ... I don't think this group and other like-minded thinkers will be able to go unsupervised much longer.
Basically, what I'm saying is that just maybe it might be wise to leave the ICBMs to the big (proprietary) boys for now. That way, we might not grab their attention until it's too late for them.
With greetings, Herbert Snorrason -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.8 (Darwin) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/
> Not to be a killjoy, but there are some elementary points here. You are > talking about designing an orbital launch vehicle, and making the full > design, schematics, control electronics and all available to all comers. > The applications such a design could - and _would_ - have are rather > magnificent. Specifically, any such vehicle could be used to move > payloads from one continent to another. There is, incidentally, a > special name for a vehicle used for that purpose.
Yes, we're quite aware of this unfortunate complication. ITAR seems to completely rule out hosting open source launch vehicle information in the US or Canada. Building orbital LVs is rather unpopular at CSTART at the moment for this very reason. Even if that project goes ahead, it is almost certain that we will still use commercial launch vehicles for our earliest projects simply because none of our own stuff will be ready in time.
It seems like our first orbital projects will almost certainly be light weight, simple satellites, launched by the cheapest proprietary option and designed primarily to test proposed communications and other hardware for use on the manned capsule (which is by far the project we have planned in the most detail).
> One thought on spaceflight which lends itself rather well to this > automated assembly line approach is the construction of large launch > vehicles by clustering small, simple rockets together. This approach > was tried in the 70s by a German company called OTRAG, but it fell > through largely for political reasons (the idea seems technically > sound).
Actually one of the key members of OTRAG, Dr. Hau-Po Mok, was teaching at the university I went to. He tought us about fluid dynamics. Sadly he passed away two years ago in a heart attack. On an occacion he presented that project. The whole idea was born out of necessity. After ww2 Germany was forbidden from building any rockets with a diameter exceeding 270mm. So they figured they'll just stack together a lot of these and see what that assembly is cabable of doing. Their calculations showed a rocket with a launch mass of about the Saturn V would be able to put about 10 tons into LEO. The modules were quite simple metal pipes with a pressure fed propellant. I can't remember the propellant type now, only that it was liquid, but can look it up if you like. It was pressure fed using nitrogen, not helium like is usual. It was chosen to reduce cost and complexity. They made a successful test launch somewhere in Africa (I think it was Zaire) before the project was shut down for several reasons. One was that the French were not all to happy with Germany developing long range rockets (quite understandable given the time and situation). But the other reason was that ESA was starting to form seriously and they were developing more conventional rockets in a European cooperation. So it was decided to scrap this project and invest into the likes of Ariane instead.
Ok so what do I think about this approach? It might be good for simple access to space, but if we are really looking to set up a continous stream of vehicles to orbit better performance design with more reusability, like I hope Falcon will prove to be look like a better choice. Also the rocket itself is just a part of the cost of a launch. There is also the cost of the launch infrastructure (OK for OTRAG this was quite small, they built a launch tower from wood they got from the local forest). But an air launched vehicle like SpaceShipTwo is much more flexible. You can assemble it anywhere in the world, then fly to an other airport with the carrier plane, refuel and it's ready for take-off. Of course the size is limited if you want to be able to use most airports but should still be good enough for small satellites. For bigger vehicles I like the sea launch, that could be made more or less independent from a single country. I'm quite surprised that the Sea Launch company went bancrupt. Launching GEO payloads from the equator should be a big advantage to all other sites except Corou. But I've seen concepts for floating launch vehicles that don't need a swimming launch platform at all (Sea Dragon, proposed by Boeing if I remember correctly)
In the end it would be nice to build something like the Loftstrom Launch Loop, but there are a few small problems to overcome before that will happen... http://launchloop.com/
For politics, I know about the delusional ways of certain governments to try to bring the whole world under their control, but in the end this looks to me very much like the Ming in the 15th century who scrapped their own fleet because of fears. It didn't do them any good in the long run and it won't do any good for these governments today either. You don't need ICBMs to cause trouble if you really want to in this world, the notion that some space exploration group would waste all their work in this way is laughable.
But as Herbert said, this is still a long way in the future. You can't do a true open source based spacecraft today because we haven't even closely developed the open source manufacturing infrastructure to that point. Of course you can still try a semi-open source project like CSTART seems to look to me, but the question is what you want to achieve. Do you want to put a wo-/man on the moon for 50 million $ with an architecture that would require a similar amount of money for each new flight? Or do you (like I) want to contribute to make spaceflight so cheap that anyone will be able to go out and survive there permanently? Then this is a slower approach with more work before any great results but I hope with very big long term gains.
> I would wager we could do incredible things with a much smaller > contributor base than that. The team at Copenhagen Suborbitals > (http://www.copenhagensuborbitals.com) seem to be doing very well with > their one man suborbital microspacecraft project (first unmanned > launch scheduled for June or July this year), and their team is just > 17 people large (with the vast majority of the work being done by a > core team of 2).
Thanks for the link, I'll have a look at their project.
> Actually one of the key members of OTRAG, Dr. Hau-Po Mok, was teaching at the > university I went to. He tought us about fluid dynamics. Sadly he passed away > two years ago in a heart attack.
It's really cool that you got to learn from someone with such excellent experience. It's a shame to hear he's died. As far as I know, the founder of the company, Lutz Kayser, is still doing well. He visited Armadillo Aerospace's facility somewhat recently, I recall reading.
> Their calculations showed a rocket with a launch mass of about the Saturn V > would be able to put about 10 tons into LEO. The modules were quite simple > metal pipes with a pressure fed propellant. I can't remember the propellant > type now, only that it was liquid, but can look it up if you like. It was > pressure fed using nitrogen, not helium like is usual. It was chosen to > reduce cost and complexity. > They made a successful test launch somewhere in Africa (I think it was Zaire) > before the project was shut down for several reasons. One was that the French > were not all to happy with Germany developing long range rockets (quite > understandable given the time and situation). But the other reason was that > ESA was starting to form seriously and they were developing more conventional > rockets in a European cooperation. So it was decided to scrap this project > and invest into the likes of Ariane instead.
It's been a while since I read up on OTRAG in too much detail, but if I recall correctly, the pressurant was actually just compressed air, the propellants were LOX and kerosene, and the African launches were done in Libya. I could be wrong about any of these, though.
> But an > air launched vehicle like SpaceShipTwo is much more flexible. You can > assemble it anywhere in the world, then fly to an other airport with the > carrier plane, refuel and it's ready for take-off. Of course the size is > limited if you want to be able to use most airports but should still be good > enough for small satellites.
It is true that a vehicle like the SpaceShipN vehicles can be assembled at point A and then flown to point B for launch, but there still has to be a point A - somewhere with a workshop large enough to create the entire vehicle. The big appeal of the OTRAG approach for CSTART was that the booster could be built at points A, B, C,..., Y and then shipped to point Z for launch. Constructing the individual modules would require only a fairly small and simple workshop, well within the means of a dedicated hobbyist. With this approach, access to space can be constructed in a *massively parallel fashion* at low cost. This approach takes maximum advantage of the open source approach. I will admit though that it has downsides, for example there is little scope for reusability.
> For bigger vehicles I like the sea launch, that could be made more or less > independent from a single country. I'm quite surprised that the Sea Launch > company went bancrupt. Launching GEO payloads from the equator should be a > big advantage to all other sites except Corou. > But I've seen concepts for floating launch vehicles that don't need a swimming > launch platform at all (Sea Dragon, proposed by Boeing if I remember > correctly)
If you are interested in sea launches, you should definitely talk to the guys from Copenhagen Suborbitals. They plan to launch their manned suborbital craft from a float launch pad outside of Danish territorial waters to get around various regulatory hassles. One of their team previously participated in the design and construction of the world's largest amateur submarine (the UC3 Nautilus, see http://www.uc3nautilus.dk/), so I believe they have what it takes to pull this off.
> In the end it would be nice to build something like the Loftstrom Launch Loop, > but there are a few small problems to overcome before that will happen... > http://launchloop.com/
I hadn't heard of launchloop before, thanks for the link, I will check it out.
> But as Herbert said, this is still a long way in the future. You can't do a > true open source based spacecraft today because we haven't even closely > developed the open source manufacturing infrastructure to that point. > Of course you can still try a semi-open source project like CSTART seems to > look to me, but the question is what you want to achieve. > Do you want to put a wo-/man on the moon for 50 million $ with an architecture > that would require a similar amount of money for each new flight? > Or do you (like I) want to contribute to make spaceflight so cheap that anyone > will be able to go out and survive there permanently? > Then this is a slower approach with more work before any great results but I > hope with very big long term gains.
This is perhaps a legitimate criticism of our current plans re: manned spaceflight. It betrays our origins as a very informal, almost whimsical group interested in getting a human on the moon as simply and cheaply as possible, without much thought about the bigger picture. Now that we have become a little more organised and directed we are trying to remold our ideas and projects into something of a more coherrent direction. It might be that our second manned spaceflight project, should we get that far, will be more geared around minimal cost, highly reusable, quickly relaunchable ideas.
> It's been a while since I read up on OTRAG in too much detail, but if > I recall correctly, the pressurant was actually just compressed air, > the propellants were LOX and kerosene, and the African launches were > done in Libya. I could be wrong about any of these, though.
I can't remember it very well either, only heard that one presentation about the project. And Mok was talking a lot about the different design choices they had to make along the way, so I could me mixing it up. But the one thing I clearly remember is the low payload mass to LEO for a very big rocket. That and the lack of reusability seem to make the apprach not very well suited as a long term solution.
> If you are interested in sea launches, you should definitely talk to > the guys from Copenhagen Suborbitals. They plan to launch their > manned suborbital craft from a float launch pad outside of Danish > territorial waters to get around various regulatory hassles. One of > their team previously participated in the design and construction of > the world's largest amateur submarine (the UC3 Nautilus, see > http://www.uc3nautilus.dk/), so I believe they have what it takes to > pull this off.
Yes I've looked at the link you provided before, they seem to be quite far with their project already, definitely looks interesting. I will gladly help once I will have brought my current projects on the way.
> This is perhaps a legitimate criticism of our current plans re: manned > spaceflight. It betrays our origins as a very informal, almost > whimsical group interested in getting a human on the moon as simply > and cheaply as possible, without much thought about the bigger > picture. Now that we have become a little more organised and directed > we are trying to remold our ideas and projects into something of a > more coherrent direction. It might be that our second manned > spaceflight project, should we get that far, will be more geared > around minimal cost, highly reusable, quickly relaunchable ideas.
The suborbital rocket project seems doable, it's only the Moon landing one that I have doubts about. 50 millions is no small pricetag, you can take a Soyuz to the ISS for that. Basically I believe human spaceflight is unlikely to become viable before the cost to orbit per mass can be cut by at least a magnitude. All the NewSpace companies are trying to accomplish this and it should be happening in the coming years now if developments continue in the pace they had been going on in the past decade. As for the truly OpenSource part I would go with component development first, there is really a lot to do from gyros to engine nozzles. But we need to set up the basic production infrastructure in the first place. That will be a lot of work in itself.
> it's only the Moon landing one > that I have doubts about. 50 millions is no small pricetag, you can take a > Soyuz to the ISS for that.
Sure, 50 million is enough to put a Soyuz into LEO. The Soyuz TMA has a mass of 7220 kg. So a one person conical capsule (basically a modernised Mercury) with a mass of 1000 kg (this isn't a made up figure, it's been extrapolated from mass breakdowns of Mercury and Gemini and I think it is possible) can be put into LEO with 6000 kg of propellant behind it for this price. Okay, this is actually an exaggeration, you have to account for the mass of the propellant tank, engines, etc. Let's say 5000 kg of propellant for the sake of argument. If the propellants have a vacuum specific impulse of 250 s (which is achievable using hydrogen and oxygen), then the rocket equation gives a total impartable delta-v of 4390 m/s, which is more than enough for a TLI burn (these are around 3100 m/s). It's not enough for a TLI plus lunar insertion and lunar escape burns, so it couldn't do a full lunar landing, but it could do a circumlunar flyby. Now, with the Falcon 9, 50 million will buy you 10,400 kg into LEO, more than the Soyuz mass used above, which by our calculations is *just* enough to get a 1000 kg capsule, a 300 kg open-cab lander and all required propellant for a return lunar landing.
Of course, the spacecraft aren't free so the actual price is 50 million plus spacecraft costs. The 50 million total figure you've seen in our material is due to us accidentally using an outdated Falcon 9 cost of 35 million (this was the estimated price in 2006) and figuring 15 million would certainly be enough for the spacecraft. We'll have to revise the total cost estimate in light of this, obviously, but it's still definitely under 100 million.
> Sure, 50 million is enough to put a Soyuz into LEO. The Soyuz TMA has > a mass of 7220 kg. So a one person conical capsule (basically a > modernised Mercury) with a mass of 1000 kg (this isn't a made up > figure, it's been extrapolated from mass breakdowns of Mercury and > Gemini and I think it is possible) can be put into LEO with 6000 kg of > propellant behind it for this price. Okay, this is actually an > exaggeration, you have to account for the mass of the propellant tank, > engines, etc.
I know this is theoratically doable.
> Let's say 5000 kg of propellant for the sake of > argument. If the propellants have a vacuum specific impulse of 250 s > (which is achievable using hydrogen and oxygen),
Have you made any specific engine designs? LOX/LH2 should be capable of more that that, more like 400-450. The Ariane's HM7 has 444s at 35 bar combustion chamber pressure http://en.wikipedia.org/wiki/HM7B But it's turbopump fed. You would get less chamber pressure without the turbopump, but should still be quite high exhaust velocity. I heard with this propellant it is tricky to restart the engine. But that might be a turbopump related problem, so it probably is no concern for a pressure fed solution.
I guess you already made more detailed calculations concerning ISP. But you should build a small engine and test reignition if you want to be sure about that part.
> then the rocket > equation gives a total impartable delta-v of 4390 m/s, which is more > than enough for a TLI burn (these are around 3100 m/s). It's not > enough for a TLI plus lunar insertion and lunar escape burns, so it > couldn't do a full lunar landing, but it could do a circumlunar flyby. > Now, with the Falcon 9, 50 million will buy you 10,400 kg into LEO, > more than the Soyuz mass used above, which by our calculations is > *just* enough to get a 1000 kg capsule, a 300 kg open-cab lander and > all required propellant for a return lunar landing.
> Of course, the spacecraft aren't free so the actual price is 50 > million plus spacecraft costs. The 50 million total figure you've > seen in our material is due to us accidentally using an outdated > Falcon 9 cost of 35 million (this was the estimated price in 2006) and > figuring 15 million would certainly be enough for the spacecraft. > We'll have to revise the total cost estimate in light of this, > obviously, but it's still definitely under 100 million.
It all sounds very exciting, question is just how you get people to fund it. I guess if you can prove it successful for several times you even might get some of those ISS tourists interested. But it's still very much out of reach of us simple non-billionaires.
> Have you made any specific engine designs? LOX/LH2 should be capable of more > that that, more like 400-450.
Oh, do pardon me, I absolutely meant to say 450s, which is the very upper range of what LOX/LH2 can do. In fact, you *need* 450s to get this to fit on a Falcon 9 (or you need to be able to get the hardware masses quite a bit lower than our estimates of what is reasonable - which may in fact be possible), so it's very close to the line. 250 s would not be anywhere near enough, I had that figure on my mind from work I was doing recently on our suborbital project.
> The Ariane's HM7 has 444s at 35 bar combustion > chamber pressure > http://en.wikipedia.org/wiki/HM7B > But it's turbopump fed. You would get less chamber pressure without the > turbopump, but should still be quite high exhaust velocity. I heard with this > propellant it is tricky to restart the engine. But that might be a turbopump > related problem, so it probably is no concern for a pressure fed solution.
We will certainly be using a pressure fed solution for simplicity. I don't specifically know what impact this has on reignitability, it is something we will have to look into. We could certainly use the help of people who have real experience with this stuff.
> It all sounds very exciting, question is just how you get people to fund it. I > guess if you can prove it successful for several times you even might get > some of those ISS tourists interested. But it's still very much out of reach > of us simple non-billionaires.
$100 million is a lot of money in the sense that the number of people who could afford to buy themselves a ticket to the moon at that price is very small. It's not so bad from the point of view of "we need to get this much money to send our first person up". Figures in the $10 million range are routinely raised through sponsorship and donations to finance teams entering things like high profile yacht races. Surely a manned lunar landing could attract a lot more than these sorts of endeavours? It's the kind of thing that wealthy IT executives, for instance, might be willing to throw rather a lot of money at. Also, if it looks like we're actually going to pull this off, there's always the chance that SpaceX will give us a discount on the launch simply in order to secure themselves the prestige of being the company that build the rocket that returned man to the moon.
Of course, this approach works well for the first time "proving that we can do it, despite the doubts of the world!" mission. It's not going to work for a sustainable industry of lunar landings. In a sense this isn't a problem for us because CSTART isn't a space tourism company or anything like that. We're heading to the moon to explore and to do science.
> Oh, do pardon me, I absolutely meant to say 450s, which is the very > upper range of what LOX/LH2 can do. In fact, you *need* 450s to get > this to fit on a Falcon 9 (or you need to be able to get the hardware > masses quite a bit lower than our estimates of what is reasonable - > which may in fact be possible),
You will also have a problem with the chamber walls. I don't want to say anything totally wrong here and you're almost making me get out the calculator :-) , but the max temperatures for that ISP and propellant should be about 3000K. So you would need some very good cooling and/or expensive materials. Tungsten is not taken because it is eroded fast by the propellants at this temperature if I remember correctly. I've had a radiation cooled nozzle made of pure platinum once in my hand, but that's not really cheap to experiment with I would say.
> We will certainly be using a pressure fed solution for simplicity. I > don't specifically know what impact this has on reignitability, it is > something we will have to look into. We could certainly use the help > of people who have real experience with this stuff.
I don't have any real experience with chemical rockets either. Could build you a nice high quality vacuum chamber though, but I guess that wouldn't help you much either :-) It would be great to get some experience, the only problem is if you work on too many projects at the same time you won't make much progress in any of them.
> Surely a manned lunar landing could attract a lot more than these > sorts of endeavours? It's the kind of thing that wealthy IT > executives, for instance, might be willing to throw rather a lot of > money at.
> In a sense this isn't a problem for us because CSTART isn't a space tourism > company or anything like that. We're heading to the moon to explore > and to do science.
But if you're just out to explore, then why take humans? A solar powered rover on the Moon would be much smaller mass and work for years. There is a reason why the likes of Elon Musk say they're out to make mankind a multiplanetary species. Statements like this would get you a laugh at best or in trouble if you were working as an employee for one of our glorious well funded government space programs.
> You will also have a problem with the chamber walls. I don't want to say > anything totally wrong here and you're almost making me get out the > calculator :-) , but the max temperatures for that ISP and propellant should > be about 3000K. So you would need some very good cooling and/or expensive > materials. Tungsten is not taken because it is eroded fast by the propellants > at this temperature if I remember correctly. I've had a radiation cooled > nozzle made of pure platinum once in my hand, but that's not really cheap to > experiment with I would say.
Since LH2 and LOX are both cryogenic liquids, regenerative cooling is a definite possibility. I fully admit I don't know if regenerative cooling will work in this situation. I'm not a rocket scientist and nobody currently at CSTART is. Most of us aren't much at all in the way of experts on anything, we just have good broad knowledge (degrees in things like mechanical engineering and applied mathematics). What we've done is crunch the basic numbers are described an overall mission architecture built on existing technology / test ideas and shown that a minimalist manned lunar return trip can be done for maybe $60 or $70 million dollars. What we desperately need now are lots of people with all sorts of experience to help us fill in details like these, help us figure out how to go about actually building this stuff, help us figure out how to finance the efforts, etc. We're headed to SpaceUp later this month to try to find some of these people. I am hoping that the Open Manufacturing Network can help us find some people to handle that middle problem.
> I don't have any real experience with chemical rockets either. Could build you > a nice high quality vacuum chamber though, but I guess that wouldn't help you > much either :-)
It won't help with propulsion, but it could certainly be helpful when it comes to testing that our capsule is pressure-tight, and especially testing EVA procedures (our capsule features an EVA hatch much like Gemini - EVA requires venting and repressurising the capsule). We're far away from having hardware ready to put in a chamber right now, of course, but the need will definitely be there one day!
Perhaps I'm being optimistic, but I think that the general public would be a lot more interested in / excited by a manned lunar landing than a solar sail test. Hopefully, anyway.
> But if you're just out to explore, then why take humans? A solar powered rover > on the Moon would be much smaller mass and work for years. There is a reason > why the likes of Elon Musk say they're out to make mankind a multiplanetary > species. Statements like this would get you a laugh at best or in trouble if > you were working as an employee for one of our glorious well funded > government space programs.
Okay, I need to clarify a few things.
First and foremost, in retrospect I never, ever should have said that CSTART was doing anything to explore and do science. I retract this statement. CSTART is an open, collaborative effort and we do anything that we do for all of the myriad reasons that our individual contributors want to see us do them. Not I nor anybody else speaks with any kind of authority about "why" we do things, we just do things because our community wants us to. When I said "exploration and science", I was speaking only for myself.
I can say that as far as I know, nobody involved in CSTART yet is viewing CLLARE as a leadup to any kind of high-volume tourist application. Thus, it hasn't really been designed toward this end.
Now, when *I* said "exploration", I suppose I implicitly meant "human exploration". Going there for the sake of being there. I personally would love to see mankind become a multiplanetary species. I agree with the idea that this is essential to our long term survival. That said, I don't really see CLLARE as much of a lead up to this either, although components of it could be used to drop supplies to a colony. Other open source groups, like the Open Luna Foundation, obviously are working on things which are a lead up to this. CLLARE is designed to get someone there quickly and cheaply to prove that simple, low cost spaceflight by large, collaborative teams is possible. It is possible that in the future CSTART will have other projects which are more geared toward long term human presence on the moon. Personally, I would like to see this. But we're going to pace ourselves and try to achieve simple things before aiming for huge things.
> Since LH2 and LOX are both cryogenic liquids, regenerative cooling is > a definite possibility. I fully admit I don't know if regenerative > cooling will work in this situation.
What know about that is you will get thermal erosion at the cooling channels if you re-ignite often. On one side there is the extremely hot gas on the other cryogenic liquid. That leads to uneven expansion of the walls due to heat. Each time the engine is turned off the channels bend back into the neutral position, then bend again after re-ignition. It's called the "doghouse effect" because the side closest to the chamber will bend into the shape of a roof after several ignitions. Shouldn't be much of a problem unless you are planning to do a lot of burns. Will be bigger trouble to set up the cooling channels in a way that they survive the first burn in the first place.
> I'm not a rocket scientist and > nobody currently at CSTART is. Most of us aren't much at all in the > way of experts on anything, we just have good broad knowledge (degrees > in things like mechanical engineering and applied mathematics). What > we've done is crunch the basic numbers are described an overall > mission architecture built on existing technology / test ideas and > shown that a minimalist manned lunar return trip can be done for maybe > $60 or $70 million dollars.
The people who originally "invented" rocket science were not rocket scientists either. They were enthusiastic visionaries of a similar kind as the group of people you describe. Unfortunately they had the very same problem with funding until politics got interested in what they were doing when it occured to the government hierarchy what great weapons those rockets would make. Maybe we will be able to pull this off without governments this time, but I believe the best way to do this is to get the effort needed into a range that we can handle ourselves. And for this we need DIY component development. For this we need to make open source manufacturing cabable of producing those components. Which is a huge load of work in itself.
> What we desperately need now are lots of > people with all sorts of experience to help us fill in details like > these, help us figure out how to go about actually building this > stuff, help us figure out how to finance the efforts, etc. We're > headed to SpaceUp later this month to try to find some of these > people. I am hoping that the Open Manufacturing Network can help us > find some people to handle that middle problem.
Definitely for a project of this size we need a lot of people to cooperate. We should also make sure different projects will be able to use each other's work for their own developments. I can help you with advice for now, but not much else until I got my own stuff together.
> It won't help with propulsion, but it could certainly be helpful when > it comes to testing that our capsule is pressure-tight, and especially > testing EVA procedures (our capsule features an EVA hatch much like > Gemini - EVA requires venting and repressurising the capsule).
For simple testing of pressure tightnest the easiest way to go is to increase the pressure in the capsule by the difference you will have between vacuum and cabin atmosphere. This can be done before any more accurate vacuum chamber testing.
> What know about that is you will get thermal erosion at the cooling channels > if you re-ignite often. On one side there is the extremely hot gas on the > other cryogenic liquid. That leads to uneven expansion of the walls due to > heat. Each time the engine is turned off the channels bend back into the > neutral position, then bend again after re-ignition. It's called > the "doghouse effect" because the side closest to the chamber will bend into > the shape of a roof after several ignitions. > Shouldn't be much of a problem unless you are planning to do a lot of burns. > Will be bigger trouble to set up the cooling channels in a way that they > survive the first burn in the first place.
This is a good thing to know, thank you very much. The bare minimum number of burns that would be involved is 3: trans lunar injection, lunar orbit insertion and trans Earth injection. Of course, it would be sensible to ensure that the engine can survive more than this bare minimum so that we have a safety margin to do minor corrections on course.
>> I'm not a rocket scientist and >> nobody currently at CSTART is. Most of us aren't much at all in the >> way of experts on anything, we just have good broad knowledge (degrees >> in things like mechanical engineering and applied mathematics). What >> we've done is crunch the basic numbers are described an overall >> mission architecture built on existing technology / test ideas and >> shown that a minimalist manned lunar return trip can be done for maybe >> $60 or $70 million dollars.
> The people who originally "invented" rocket science were not rocket scientists > either. They were enthusiastic visionaries of a similar kind as the group of > people you describe. Unfortunately they had the very same problem with > funding until politics got interested in what they were doing when it occured > to the government hierarchy what great weapons those rockets would make.
This is true, and quite an inspirational thing to keep in mind, thanks. :)
> Maybe we will be able to pull this off without governments this time, but I > believe the best way to do this is to get the effort needed into a range that > we can handle ourselves. And for this we need DIY component development. For > this we need to make open source manufacturing cabable of producing those > components. Which is a huge load of work in itself.
I agree that DIY component development would be a fantastic boon to CSTART and other projects like it. I am very interested to see what can be achieved in this field.
> For simple testing of pressure tightnest the easiest way to go is to increase > the pressure in the capsule by the difference you will have between vacuum > and cabin atmosphere. > This can be done before any more accurate vacuum chamber testing.
Of course, this is certainly something that we should try first.
> I agree that DIY component development would be a fantastic boon to > CSTART and other projects like it. I am very interested to see what > can be achieved in this field.
It might take quite some time to get it to the level where we will be able to DIY spaceship parts, but one has to begin somewhere... And open manufacturing will solve a lot of other problems along the way, too.
