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#51 2004-05-05 08:09:09

Bill White
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Registered: 2001-09-09
Posts: 2,114

Re: Low-cost-reusable vehicle design-FICTION *2* - last topic got borked

Back to DH-1 economics... unfortunatly there are only like 200 satellites total surrounding the Earth, so there isn't much market for repairing them, especially as their electronics become obsolete. And how do you intend to get the fuel or the "larger payloads" up to LEO for the DH-1? Multiple launches to haul GEO injection fuel will at least quadruple the number of flights needed, and you still can't make two halves of one big payload.

No market for repairing satellites? You sure about that? wink
http://www.spacedaily.com/news/salvage- … e-04a.html
Alternatively sell them second hand. Profit margin might be lower but there is always a market for second hand that costs half as much and can do most of what a new item can. Lastly there is the insurance sector, who will be very interested in an alternative to writing off a $100M+ sat & launch.

And why do you object so strongly to multiple launches? Multiple launches is the whole point of the DH-1! It brings the cost down. 15MT to GEO would require something like 40 refueling flights, but most repair missions probably won't require that much mass. 1MT would do in some cases, especially when it's something as simple as a stuck spring or a blown fuse.

ANTIcarrot.

Okay lets look at this.

And why do you object so strongly to multiple launches? Multiple launches is the whole point of the DH-1! It brings the cost down.

Suppose you lose one DH-1 per 1000 flights. Skip the paylaod loss issues. 5000 pounds is trivial. Its the $250 million vehicle that just exploded.

At 1 total loss per 1000 flights you need to allocate $250,000 per flight for a replacement reserve. If you lift 5000 pounds per flight, you need to add $50 per pound to your base payload price to offset this contingency. If your loss rate were 1 in 100, then you need to charge an additional $500 per pound to cover the cost to replace lost vehicles.

We haven't paid the widow yet, either. ???

How many flights can a DH-1 make before it needs to be replaced?

$250 million just may be waaay too expensive a box for carrying only 5000 pounds of payload.

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#52 2004-05-05 14:03:47

ANTIcarrot.
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From: Herts, UK
Registered: 2004-04-27
Posts: 170

Re: Low-cost-reusable vehicle design-FICTION *2* - last topic got borked

It's supposed to be 0.999% reliable, equal to a modern business jet, and to require about as much maintinance. Anyone know how much that is? wink I was a litle conservative in my earlier estimates: Engines and tanks should last a hundred flights before serious maintinance/replacement is required. I'd assume that they'd be able to do 1000 flights apeace, eventually.

But even if it conks out after a hundred flights, a DH-1 can put 220,000kg into orbit during it's lifespan. And if an organisation is willing to spend extra money on down-range recovery of the first stage, that ammount can be 770MT to 1100MT. Hardly an ammount to be sneazed at, especially for a space-agency's first vehicle.

Don't forget the purpose of the DH-1 is not to just get people and cargo into space, but to get organisations up there as well.

ANTIcarrot.

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#53 2004-05-05 15:26:05

ANTIcarrot.
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From: Herts, UK
Registered: 2004-04-27
Posts: 170

Re: Low-cost-reusable vehicle design-FICTION *2* - last topic got borked

And, ah, I think some people on this board are confusing running costs with customer prices. Example:

ANTI's All Attitude Astranautics Agency owns two DH-1 ($250M each) and one launch facility ($150M). I owe the bank $65M a year in repayments.

Because AAAAA operates DH-1s as AM&M intended, each launch costs the company $1M + TAX. However the company sells at $2,000/lb, which includes on-site test, simple fixes and/or return to earth if needed.

Alternatively, tickets for one of 5 passenger seats can be purchased for $300K. This is a low profit line intended to increase interest in orbital tourism, and is a loss leader tactic.

A cargo flight therefore makes me $1800/lb profit. To break even  and cover the bank payments AAAAA need to launch 37,000lb, or launch the DH-1s a total of 8 times a year. This is roughly equal to a proton or Ariane 5 launch. I'm pretty sure even a low profile start up can manacge that much custome in a single year.

ANTIcarrot.

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#54 2004-05-05 15:47:24

Bill White
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Re: Low-cost-reusable vehicle design-FICTION *2* - last topic got borked

Why will they pay you $2000 per pound when the SeaLaunch Zenit 3SL is cheaper per pound and can lift larger payloads?

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#55 2004-05-05 16:32:34

ANTIcarrot.
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Posts: 170

Re: Low-cost-reusable vehicle design-FICTION *2* - last topic got borked

http://www.futron.com/pdf/FutronLaunchCostWP.pdf
According to this Sealaunch charges $2431/lb. The SL homepage doesn't seem to give away prices. (Do any of them?) May I ask what your source is?

They launch with me because:
*I can significantly undercut the competition and still break even with only one or two launch contracts a year.
*I can test for and fix satellite failures in orbit, where as SeaLaunch just shugs their shoulders and says, "whoops."
*I don't require the customer to put all their eggs in one basket.
*I can put more into GSO than SeaLaunch for the estimated price per launch of $80M.
*I can assemble larger sattilites in orbit than can be folded into a Zenit launch shroud.
*Five or ten years down the line I can go back up there and refuel/upgrade/repair for much lower cost than replaceing it brand new.
*I'm more enviromentlly friendly and don't dump stages into the ocean. wink

This assumes that the DH-1 functions as advertised. Personally I'd favour a *metric* 'EI-2' which put up 5000kg, but still I think the DH-1 has it's uses.

ANTIcarrot.

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#56 2004-05-05 16:52:31

GCNRevenger
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Re: Low-cost-reusable vehicle design-FICTION *2* - last topic got borked

No, you will not be launching. Why?

The DH-1 cannot access GEO directly. Multiple (I think four, payload + GTO stage + 2x Fuel) launches would be needed to launch a satellite half the size that SeaLaunch can loft. So, you need eight launches to match what one Zenit-IIISL can do. Zenit already comes with the GEO injection stage too I believe, so this would be an extra expense for the DH-1 method.

At $2,000 a pound, you would be charing your customers $80Mn for what Zenit or Delta-II can already do reliably for about the same. So unless you can substantially undercut the competition, then why would any company not pay the price for a proven vehicle? And remember... eight times the flights, eight times the risk, and this is assuming that each mission (not launch) goes as planned every time. Risk, like time, is money.

Just say the phrase "assemble satellite in orbit" and watch the blood drain from the investors' faces...

And no, you can't go up to a higher orbit to retrieve/repair older satellites, because of the huge amount of fuel and LSS you would need to push the upper stage up there and back, it would be cheaper just to launch a new one. This is again assuming that the mission goes as planned, and that the satellite can actually be fixed easily while in orbit.

Nor can you cram seats for six into such a small vehicle. The payload faring on the DH-1 is little bigger than a Soyuz capsule, which only really has room for two people to ride in with three seats.

Edit: Oh and it gets better... don't forget the extra engineering complexity of making two halves of one big satellite or the duplicity of hardware for making two separate ones. Alot of the mass for satellites comes from stationkeeping fuel, which you can't subdivide those fuel tanks without losing alot of volume or tank efficency.


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

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

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#57 2004-05-05 16:58:05

Bill White
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Re: Low-cost-reusable vehicle design-FICTION *2* - last topic got borked

My apologies on the figures. I use this:

http://www.futron.com/pdf/FutronLaunchC … CostWP.pdf

Zenit-2 is $1500
Zenit 3SL is $2431 as you say

but could / has Zenit 3SL come down in the face of your competition?

Protons have been cut significantly since thjis study - one Indian or Indonesian sat launch bought a Proton at nearly $1000 per pound. Link buried in the NewMars pile of posts.

Futron asserts anecdotally that launch costs have fallen 20% to 30% since the report was published and sicne they are now so low, no one will talk in public about them.

= = =

What about Progress/Soyuz from Kouru? The Baikonur figures are about $2400  yet how much more leverage would you get from Kouru?

As an aside, Progress vs Sea Launch? Any thoughts?

= = =

Bigelow's space hotel - - that is what you should pray for.

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#58 2004-05-06 03:56:10

ANTIcarrot.
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From: Herts, UK
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Posts: 170

Re: Low-cost-reusable vehicle design-FICTION *2* - last topic got borked

Well... If I was ANTI's *American* All Attitude Astranautics Agency, I could bid to launch NASA payloads at a cost no other US company could match. Under current law my company would be protected against foreign competition. ^.^

Alternatively, my space-tourism flights raise $0.5M each, so all I need to do is find 600 people a year who want to spend a few hours in zero G and are willing to cough up $300,000 for it. The ultra-rich would probably turn their noses up at such a low price, but IIRC there are enough 'merely rich' people who would be interested.

ANTIcarrot.

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#59 2004-05-06 05:10:04

GCNRevenger
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Re: Low-cost-reusable vehicle design-FICTION *2* - last topic got borked

Not if Nasa says that 5,000lbs in a dinky 9m^3 rocket is useless they won't. You cannot build a pressure vessel  or fuel tank in orbit yet; you just can't do it safely, so for the forseeable future you have to launch such modules whole. And don't go getting all "but TransHab!" either, TransHab is a ~metal~ module with semi-expandable walls, it does not collapse down to a little cube like a balloon, which would be too flimsy. Nor would 5,000lbs be enough to lift a NTR engine off the ground, or the payload dimensions be big enough for a heat shield, or a pre-assembled nuclear reactor...

The list of things that the DH-1 can't do for Nasa is a long one. In fact, its even too small to bring up an ISS science rack without design changes.

As far as commertial duties, Zenit already comes with the GEO injection stage, how much is AAAA going to charge for that? I think that would put you pretty close to the same price against a rocket with more payload capacity. Show me a company betting the farm on space tourism paying for a >$1Bn rocket and i'll show you one that nobody would invest in.


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

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

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#60 2004-05-06 07:31:38

ANTIcarrot.
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Posts: 170

Re: Low-cost-reusable vehicle design-FICTION *2* - last topic got borked

Hmm. I could have sworn I had answered these questions before GCN. Maybe we’re talking at cross purposes. Just in case, I’ll start again.

The DH-1 can be refuelled in orbit by a second DH-1. The second DH-1 has to fly 15 times before the first is fully refuelled. This costs roughly $20M dollars TOTAL.

Once refuelled the first DH-1 can accelerate itself and 2.2 tons of cargo to 7.5kmps. Alternatively it can accelerate a greater cargo to a lesser speed. Alternatively it can accelerate a greater cargo half way to 4kps, dump it, and then accelerate another 4kps.

A satellite can be broken up into two or more pieces and reassembled in orbit. No part of the satellite has to be compromised for this to happen. If you disagree name an example (unmanned) satellite.

If you refuel two DH-1s in orbit and connect them, then one of them can carry a fifteen metric ton payload to GSO, stop, unload it and return to land on earth. The other DH-1 does the same thing. Two refuelled DH-1s in orbit will cost $40M.

So for one quarter the cost of an Ariane 5, half the cost of a Zenit-3SL or Proton, or two-thirds the cost of a Long March 3B I can put up three times the payload. Of course I'd charge whatever the market would bare and pocket the difference.

Since I can undercut everyone else I will get a reasonable share of the their business, plus space tourism, and maybe astronauts or utilities to the ISS. Eurotunnel ran at a loss for ten years and the banks still haven't foreclosed on them. I can probably do at least as well.

Now you have listed a lot of things which quite rightly cannot be done with the baseline DH-1. (Though I reserve opinion on the science rack.) This is what is known as a straw-man argument. You're effectively saying that since a 747 cannot sail across the Atlantic, no-one would ever want to buy a 747 since there is no other way aside from sailing to get across.

A variant DH-1a can get to mars using the same method needed to get to GSO. Do the math if you don't believe me. So you don't need an NTR engine. And since the DH-1a is going to mars you don't need  heat shield because the DH-1a is the heat-shield and the landing platform.

There are also ways on increasing payload. A stretched second stage would increase volume. A ballistic first stage launch would at least triple the mass and only double the cost. And even if it couldn't, soyuz is a very successful design and it can't do these things either. I never said the DH-1 or a design like it could do everything, but I do believe that such an RLV could do many things for potentially lower cost then conventional rockets.

There is also more than one way to skin a cat than the NASA way or the Transhab way. Take up two balloons and fill the gap with a material. Or just take up lots of balloons and inflate them one inside the other. Both techniques could use low strength balloons which could be folded up. Or just use a smaller version of transhab.
http://www.ilcdover.com/SpaceInf/habita … ermore.htm

I also think there's merit in the idea of selling RLVs rather than payloads in the same way Boeing sells aircraft and not seats. It segregates the risk and would make banks and investors at least a little less nervous.

ANTIcarrot.
End of Text from Clipboard Row 0
Delay for long paste: 6 seconds

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#61 2004-05-06 22:26:58

GCNRevenger
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Re: Low-cost-reusable vehicle design-FICTION *2* - last topic got borked

FORTY flights? Thats 40 times the risk! Man are you even really reading what its saying? So if you flew a vehicle weekly, it could move maybe one payload trip a year? If you are dealing with LOX/LH2, much of the fuel would boil off before you get enough up there to tank the thing up.

I also no longer take the low launch costs for the DH-1 seriously... the Kistler rocket essentially IS what the DH-1 is, only much simpler and with double the payload, and it was going for $14Mn a shot. Fourteen Million Dollars. $250,000 is not a number I can even entertain serious consideration for. With a minimum sane launch cost of over a million a flight, any advantage the DH-1 had over other launchers evaporates. Fuel costs $200,000+ a shot not counting handling, and thats with not one penny for paying any of the crews or for vehicle insurance or for launch pads or for payload integration or for stage processing or for vehicle assembly... etc etc. It would be several times this figure, at the least.

And how are you going to get the payloads up there? 2.2MT at a time? Sub-deviding larger objects into smaller chunks is difficult and expensive, having to engineer all the connections and bolts and latches and hoses and such... But building things in orbit, even Transhabs, actual construction of a pressure vessel be it manned or for fuel it patently impossible with near term technology. You can't do it, its too hard. Can't be done. You just can't build anything in space yet, assembly is bad enough.

Sooo along those lines, a Mars mission with DH-1 is a punchline, not a prospect. Which is why it is somthing of a contradiction that you called my post a "straw man", since this is what you alluded that it would be able to do.


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

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

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#62 2004-05-06 22:47:45

Rxke
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From: Belgium
Registered: 2003-11-03
Posts: 3,669

Re: Low-cost-reusable vehicle design-FICTION *2* - last topic got borked

DH-1 would, OTOH the perfect vehicule to do lots of experiments with building in space, crash-course-wise: send every week another 'naut up with his lil toolkit and a bit of stuff... let them play a week, come back, next...

Given, only NAASA or someone insanely rich could develop such a crash-course, so i'm not saying it is economical, just thinking about markets for non-profit stuff...

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#63 2004-05-07 08:02:02

GCNRevenger
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Re: Low-cost-reusable vehicle design-FICTION *2* - last topic got borked

Its not about skills, its about technology and infrastructure. Building anything in zero-G in space is simply not a viable option any time soon. No welding, no riviting, anything loose floating away (screws, clamps, tools, fuses etc), having to work in gloves with big hard-rubber finger tips in a space suit that resists motion, no easy way to carefully align anything, dark for half an hour on each orbit... the list goes on. Every move astronauts make today is carefully planned and done with the utmost delicacy, and thats just to bother with a few screws and rearrange a few things, most of which is designed for easy EVA handling. BUILDING anything, like an ISS module, from basic pieces is just not going to happen... It isn't a matter of expense, its a matter of practicality; it is practical to build on the ground and attach together in space, but its NOT practical to build in space.


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

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

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#64 2004-05-07 10:26:48

ANTIcarrot.
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From: Herts, UK
Registered: 2004-04-27
Posts: 170

Re: Low-cost-reusable vehicle design-FICTION *2* - last topic got borked

GCN, if you want to talk or even argue about the DH-1 then you really need to actually talk about the DH-1, not some other RLV of your own creation. Have you actually read the book?

The key selling point is aircraft like reliability. That means that you can fly it as many times as you like for a good ten years as long as you follow the proscribed maintinance schedule. Ignore this and you're talking about a fundimentally different RLV, and just distancing yourself and your arguements from that the DH-1 is and what it can or cannot do.

the Kistler rocket essentially IS what the DH-1 is

Well... in the sense that the Saturn V was really just a bigger and more advanced V-2, yes. But that's that got to do with anything? By that arguement any SSTO is essentially just another X-33, and doomed to failure through historical precident.

You just can't build anything in space yet, assembly is bad enough.

??? You mean to say you've been getting all worked up all this time because you think 'build' is not an appropiet word for how the ISS is being put together?! Did you *really* think I was suggesting lugging up raw metal ore and blast-furnaces in two ton pieces?! Of course I mean modules!

Inflatable habitats. You say the DH-1 can't do this. I say it can. Three Inflatable Compartments from the below link would easily fit within for the DH-1's 27m^3 cargo bay and be *well* within the weight limits. The remaining half ton of cargo could be used for interior supplies and fixtures.
http://www.ilcdover.com/SpaceInf/habita … ermore.htm
Two launches for 6ICs & two more for fixtures. That's a total of 8.8 tons. Since aerospace grade engineering seems to work out at ~$10,000/kg (construction cost) the station would cost $88M. So for less than a $100M you have a 347m^3 station. For the metrically challanged that's just shy of 13,000cf, which was Skylab's volume.

Even if it cost 5 times as much, a Skylab sized station, even if empty, would appeal to many at a mere $500M. Of course we could then sell it for $1B - which would pay DH-1 loan off in one go and leave plenty of room profits.

Yes assembeling things in space presents a challange, but it would be a lot easier with the aid of industrial robotics and a pressurised dry-dock. That's for large satellites though. for smaller ones the DH-1 can act as a mini-dry-dock, as long as the mini-sat can fit out the door when finished.

And let's look at those GSO figures one last time shall we?
DH-1; 40 launches; 15MT into GSO; $40M launch cost.
Zenit; 1 launch; 5MT into GSO; $80M.
a) One is 6 times cheeper than the other, and it ain't the zenit.
b) Why do you assume the DH-1 has hidden costs, and don't make the same assumption for the zenit?

I agree that we don't have the skills for frabrication in zero-G, but that's something you made up. I never suggested it.

Though now that you mention, as Rxke says, a depressurised DH-1 cabin wouldn't be a bad place to create the technology and learn the skills. ^.^

ANTIcarrot.

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#65 2004-05-07 12:49:22

GCNRevenger
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Re: Low-cost-reusable vehicle design-FICTION *2* - last topic got borked

When you can reach airline like reliability with a rocket like the DH-1, I don't think that we'll be using staged rockets to get from the ground all the way to orbit anymore. How do you intend to achieve this level of reliability, which is many times greater than any current or past vehicle, using the same piece of hardware? Powering the thing with RL-60 engines sure won't do it.

And so, in order to get a payload of useful mass, you have to fly many times and perform a delicate docking operation each time. Flying many times multiplies the risk of failure for the mission likewise and its even worse with the docking/fuel transfer operation, especially considering the speed at which the flights must take place to mitigate fuel boiloff in orbit. And it gets better... you need two DH-1 vehicles, the GEO bound one and the fuel hauler, to launch one payload to high orbit, and the GEO bound upper stage can't be used for anything else until being fueled up and loaded, which will take months with once or twice weekly flights.

The Kistler rocket is what the DH-1 was intended to be... small payloads, fully reuseable, low cost of launch with simple operations/cheap fuel and ease of construction using proven hardware and materials. They even look similar... now, why should DH-1 cost less to fly? The K-1 costs $14M for double the payload, and it uses less expensive rocket fuel. Please, i'm eager to hear how this vehicle could possibly be flown for less than $7M needed to compete with the half-complete K-1, which would cost $280M to do what Zenit can do today right now for under $100M with this crazy refueling scheme... oh and avoid fuel boiloff and the extra cost of making lego-brick satellites, and the amoratized cost of inevitible "mission failure" for this rube-goldberg scheme.

And construction in space is exactly what you just proposed... Look, get this, TransHabs are not balloons. TransHabs are not balloons. They are conventional metal-framed pre-assembled modules, which just happen to have flexible walls to make them more efficent. Just bringin up balloons is useless; you can't put anything in them easily because there isn't anything to attach to, and the hatch sizees are limited by the DH-1, and balloons aren't all that strong structurally either... The list goes on of more reasons why launchind balloons for space stations is silly, and the list goes on with reasons why building DH-1 is silly.


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

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

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#66 2004-05-07 14:50:45

ANTIcarrot.
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Posts: 170

Re: Low-cost-reusable vehicle design-FICTION *2* - last topic got borked

There is no fundimental difference between a formula one racing car and my rover metro; bar one.

The F1 car is built to only last a single season. It's weight is cut down to the bare minimum possible, and performance pushed to the edge of the safety limits. All F1 cars are built this way, and all ELV rockets are also.

The existance and expense of an F1 car does not render a rover metro impossible though. Nor does it mean that you can't build a street-legal supercar that can go as fast as an F1 but still last many years. These things are done.

This is the arguement upon which the DH-1 hinges. The engines for example are very reliable and do not run at their highest possible thrust level. They run at lower levels and at much lower stresses, and hence last longer. RL-10s have been subjected to the kinds of flight sceduals the DH-1 would operate under and they haven't exploded.

The reason that it only launches 5000lb is that the rest of the theoretical max payload has gone into making the structure more like a an family car and less like an F1.

ANTIcarrot.

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#67 2004-05-08 10:03:55

dicktice
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Re: Low-cost-reusable vehicle design-FICTION *2* - last topic got borked

GCNR: I have no trouble envisiging erecting a rigid tetrahedron from six girders in space, and then inflating a balloon to envelop it, with four reinforced attachment points at the apexes, much as the current new Zeppelins which use blimp-like envelopes surrounding their rigid structures. Not silly at all!

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#68 2004-05-08 14:41:56

Rxke
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Re: Low-cost-reusable vehicle design-FICTION *2* - last topic got borked

Hee hee...

If you don't like DH-1 V1.0.0... There is http://www.hobbyspace.com/AAdmin/archiv … tml]Always Room For Improvement

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#69 2004-05-08 22:09:33

RobS
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Re: Low-cost-reusable vehicle design-FICTION *2* - last topic got borked

Very interesting, how they calculate the reasonable investment and manufacturing costs to make an improvement, and an interesting idea that the US Air Force should not militarize space, but be in the position to do so if there were hostilities. I suppose they won't follow that advice, but it is clever.

      -- RobS

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#70 2004-05-09 10:43:30

ANTIcarrot.
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From: Herts, UK
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Re: Low-cost-reusable vehicle design-FICTION *2* - last topic got borked

Very interesting indeed, especially since the chapter seemed to answer some of the issues raised here. Almost made me wonder if the author hadn't brought forward a later chapter for some reason or other. wink

ANTIcarrot.

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#71 2004-05-15 14:55:35

Rxke
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Re: Low-cost-reusable vehicle design-FICTION *2* - last topic got borked

I thought that, too, initially, but today there's a new chapter... but it's really part of an epilogue, so i guess the series is nearing its end sad

http://www.hobbyspace.com/AAdmin/archiv … l]Epilogue 1: Space is really a Place

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#72 2004-05-15 22:20:02

GCNRevenger
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Re: Low-cost-reusable vehicle design-FICTION *2* - last topic got borked

Still ain't gonna happen...

DH-1 is a rocket. All orbital rockets must operate under high dynamic stresses for the materials that its built out of, and is still subject to the limitations of fuel energy density and friction heating and control system accuracy and so on. The small payload mass is only a small part of the reuseable upper stage mass, so that doesn't make for a huge windfall of extra mass margin.

And that still doesn't change the fact that dinky payloads to LEO is pretty worthless, no ifs ands or buts, and if its pretty worthless then you won't make a dime selling DH-1's either.

You aren't going to build a pressurized volume like a Zeplin, either, because the balloon part isn't a balloon. Its a semi-rigid foot thick shell, and doesn't neatly fold down to a little box to cram into the DH-1's puny cargo faring.


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

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

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#73 2004-05-16 13:12:12

ANTIcarrot.
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Posts: 170

Re: Low-cost-reusable vehicle design-FICTION *2* - last topic got borked

The DH-1 is more realistic than any design for a gas core nuclear rocket. It's nothing to do with engineering, it's the simple problem of how to avoid enviromental contamination if/when an engine falls off the rocket. It's a lot more likely too, especially after accounting for the possible existance of 'Leonardo Da Vinci' style patent-protecting deliberate mistakes.

And to be completely honest GCNR, your posts have been riddled with mistakes and mistruths. You're not exactly in an unimpechable position to say whether the DH-1 is practical or not. wink

ANTIcarrot.

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#74 2004-05-16 20:25:33

RobS
Banned
From: South Bend, IN
Registered: 2002-01-15
Posts: 1,701
Website

Re: Low-cost-reusable vehicle design-FICTION *2* - last topic got borked

While I am more inclined to agree with Anti-carrott than GCNRevenger, let's not forget that the DH-1 is fiction. What I'd like to know from the author is how much the story is an attempt to be realistic and how much it is, inevitably, a story. Novels to some extent require some dramatic flair and other literary devices to be worth reading. The Rocket Company avoided a lot of that, but it had some touches, like the lunar monastery and the arund-the moon explorer who goes to Mars instead.

         -- RobS

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#75 2004-05-16 21:00:59

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

Re: Low-cost-reusable vehicle design-FICTION *2* - last topic got borked

Mistakes and mistruthes ey? Now thats pretty brash of you Anti, a person could interpret that as an accusation of lying... You continue to avoid any realistic apraisal of the situation, that the DH-1... isn't. It cannot be built with huge "engineering margins" because rockets don't have any, it cannot do anything useful save perhaps launch tourists or bulk rocket fuel because it is too small even with upgrades (no space construction, no practical competitive GEO access), and nobody will buy copies of a worthless vehicle... the DH-1 is as fiction as it gets, it would need a metastable fuel to work.

The GCNR rocket is still mostly a paper concept... a little fluid dynamics number crunching and table-top experiments, nothing of substance really... but what other concepts are available that provide high thrust and >1000sec ISP that don't require large technological advances? A GCNR engine if it is built will probably be fired only in space, the fuel is kept separate from the engine, and fresh U-235 is only a weak alpha emitter... eliminating serious threat of contamination if there were an accident.


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

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

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