Low-cost-reusable vehicle design-FICTION - possible to actually do this today?

Rxke · 2003-12-24 16:22:36

Just to notify there are further updates on the on-going story, all equally detailed...
One chapter about different ways to use a heat shield, for instance... Amazing stuff.

Ok, this is fiction, but the science behind it is oh-so interesting...

Rxke · 2003-12-24 18:52:43

To make navigating a bit easier: The Rocket Company

Gennaro · 2003-12-26 05:09:09

This is all so interesting. Thanks for the link!

But I got soooo disappointed when they opted for a two-stage vehicle.

I demand fully reusable VTOVL RLV! Nothing more, nothing less.

Rxke · 2003-12-26 06:08:03

But it still is totally reusable, it just separates, and after landing they mate the two stages again. I thought the reasoning behind the two-stage approach made a lot of sense... payload-wise...

Gennaro · 2003-12-26 17:12:12

But it still is totally reusable, it just separates, and after landing they mate the two stages again. I thought the reasoning behind the two-stage approach made a lot of sense... payload-wise...

I know, I know, I'm just being obstinate and unreasonable.

Question: what will the stage reassembly mean in terms of additional servicing and turn around?
You might say I'm childishly asking for the impossible, but I don't percieve the final goal for RLV's/SSTO's to be a system that can go to LEO, make a nice turn and land again. Rather, the final objective is to ultimately break free from orbit entirely, land somewhere else and then return. In that case it might be beneficial to carry along your tanks, thus making refuelling of the vehicle possible.

Whatever it takes, nuclear engines, exotic technology and risky development, just meet the stated objective of a truly reusable single stage design, landing under its own power. (Naturally we'd start with just making it to LEO and back.) If you can pull it off however, what's left at the end of the day? Well you'll need more rocket fuel, but so what? Propellant is cheap; the solar system will open itself up for you.

Delta V to escape is about 12 km/s from Earth and 5.5 km/s from Mars. Is it really absolutely impossible to do this directly with anything but a traditional chemical rocket dropping off its hardware as it goes along?
For a comparison, delta V from Earth surface to LEO is 9 km/s up and 9 km/s down.

Rxke · 2003-12-26 17:23:04

I have to agree with your vision, but the series opted for this design for the simple reason it's the most 'economical survivable' thing to do, today...
Let's face it, there's virtually no space market, except for some big comm sats and a probe or so every other year...

Building their ship could support the existing market, outcompeting rivals, and open up the market for more initiatives, and once there's a bigger market, totally reusables *will* be built, for there'll be a demand, a demand that is not there, today.
Shuttle would've been more economical if it could launch every two, three weeks, instead of twice, three times a year, but there simply is not enough stuff to launch...

Gennaro · 2003-12-26 17:45:53

Allright, the novel has its scope and it's still an excellent read.

Rxke · 2003-12-26 17:58:55

We now any billionaires that have time for a good read?

RobS · 2003-12-27 02:41:16

I find it absolutely fascinating. The solution to the one stage/two stage problem seems brilliant to me: launch the first stage straight up and recover it where you launch it! So simple! And if you make the first stage bigger, it means you can launch into a higher orbit and could put more mass there because the fuel in the second stage needs to achieve a lower orbital velocity. The chapters about the heat shield and the tanks, potentially very boring, kept my interest. There are a lot of lessons in the story about not rejecting old ways because there are prejudices against them.

-- RobS

Rxke · 2004-01-08 06:57:41

New chapter has been posted...

chapter 11

Rxke · 2004-01-10 04:36:15

Their orbital abort mode.... If this were ever developed (and why not?) I wonder how long before some adrenalin junky would push the big red button, just for the kick of a one-person re-entry... Sounds like lot's of 'fun'

Rxke · 2004-02-21 15:21:41

Another chapter of interest, maybe.. low cost-sats (1 million+ 0.5 million upper stage) discussed... a 1000 pounds to Mars orbit on the cheap... Add 100$/ pound launch cost: total 1600000$...

[http://www.hobbyspace.com/AAdmin/archiv … page1.html]Cargo, cheap probes etc

RobS · 2004-02-22 12:32:09

Yes, the new chapter is intriguing, but it makes me suspicious. Maybe it's true that if we could launch into low earth orbit cheaply, we'd be in the position to send out hundreds of probes instead of dozens. If so, why isn't someone doing something like this with a few probes, though?

-- RobS

Rxke · 2004-03-22 12:49:03

Their last chapter talks about a 3-7 crew to Mars for a measly half a billion $....

[http://www.hobbyspace.com/AAdmin/archiv … page1.html]http://www.hobbyspace.com/AAdmin....e1.html

*And* mentions Robert Zubrin and the Mars Society!

RobS · 2004-03-22 18:34:39

Yes, I just saw the Mars chapter today, too, and wrote the author with a few questions. We'll see whether he responds. I am curious how a manned mission to Mars can be conducted with 20,000 lbs (9 tonnes) of supplies, including reactor, hab, vehicle, and food.

I see someone asked a question about reentry. The Rocket Company novel uses a heat shield that is water cooled somehow, but I don't know how.

-- RobS

SBird · 2004-03-22 22:04:54

I just read through the story up through chapter 16 or so. The author(s) seem to have a good grasp of rocket design. However, a lot of the design ideas they posit seem just wierd. For example, they go through a history of reentry heat shields and talk about how the Apollo capsule and the latest Chinese launches used bathroom caulk and resin treated wood to illustrate that you can get good performance from a disposable heat shield. Then they go on to propose this complicated shape memory metal alloy plate with microholes venting hydrogen.

There's a lot of times where the choices made for the rocket componentry seem arbitrary and sometime seem to go against the arguments stated just a paragraph before without any explanation as to why. Also, I just find it hard to get excited about a description for a reusable small lift booster. If their system was capable of lifting more than 50 tons to LEO, I'd be interested as that's pushing into Mars Direct territory.

However, the proposal that you're going to have a Mars mission capability with a cargo mass of 9 tons is just silly. Zubrin's estimates were at the 25-30 ton range for a 4 person crew and were really pushing the lower end of what I would consider safe levels of redundancy. It really makes me wonder if the rest of their figures are as unrealistic.

GCNRevenger · 2004-03-22 22:25:12

Mars for one half of one billion 2004 US dollars with only nine tons of supplies?

Ummmmm "yeah" suuuure...

Have to agree with Sbird again about some of the crazy stuff in here... activly cooling a heat shield with water would get mighty heavy, and cooling with LH would be mighty bulky, and neither one very safe.

Euler · 2004-03-22 22:39:33

I think that the 20,000 lbs of supplies does not include the earth return vehicle or its fuel. With the ERV, fuel, and supplies for the return trip there is 130,000 lbs.

RobS · 2004-03-22 23:02:16

I can't figure out the nine tonnes either; it isn't right. Yes, it is correct that it doesn't include the ERV or fuel; but it STILL isn't enough.

I think the authors have a good point about launch mass, though. If one were to build a reusable vehicle to put 25 or 50 tonnes into orbit at once, it would be expensive to design and build and it would be doomed financially because it would have to launch thousands of tonnes to cover its costs. There is no market for thousands of tonnes, and by the time such a market developed the company would go bankrupt. But 5,000 pounds (2.2 tonnes) to LEO is enough to launch several tourists at a time and enough to launch many satellites. The vehicle is cheaper to develop and build, and the quantity it has to launch into orbit per year to make a profit is less. Thus it represents a reasonable goal for a reusable vehicle. If you need 50 tonnes in orbit, you fly the vehicle 20 times, until demand increases and allows development of a larger successor vehicle.

-- RobS

Rxke · 2004-03-22 23:49:08

I'm a 'fan' of the rocket Society, but... Sometimes their chapters seem to be thrown together to reach a deadline, so i guess sometimes they're just making things up.

Note, too, that their numbers keep getting better through the story, there seems little consistency, sometimes.

Still, a lot of their stuff is sound, and 'educational' enough to keep me coming back for more.

And what if 9k kg is not enough? laungh 3 of 'em (27ton) still a measly 1,5 Billion, heehee!

Paul Allen, I hope you're an avid reader of "The Rocket Company"...

DanielCook · 2004-03-23 07:40:55

Does anybody have Paul Allen's e-mail address ? - He's known to support space initiatives ... maybe he'll be interested to
fund the "Rocket Company"

And maybe to convince his old buddy William Gates to pitch in - Microsoft has $53 billion in cash available. Another market that they can monopolize.

JimM · 2004-04-11 12:51:50

"If you want cheap launching to space the vehicles have to be reusable; expendables can't do that now, and it isn't clear that even with an economy of scale that will be possible."

Sorry, this is a myth. Going reusable at this stage in the space launching business is trying to run while you can still barely crawl. It is bound to lead to disastrous failure.

One reason is that whatever the TRC people say, developing and then flying a reusable involves far more design and research time and cost than they seem to imagine. You say, "The approach of the Rocket Company seems to be that simple tried and true technology is often the way to go..." but it is not in every case, by a mile. Just to take one small example, the idea of a heat shield that can be deployed at the rear of the vehicle to cover the engines and so permit rear-first reentry is interesting but has never been done in real life. I'd bet just to get that alone working with reasonable reliability and safety would probably cost a couple of billion dollars.

"Why put a pilot in the first stage?... With good computers, rockets don't explode nowadays; if an engine has a serious problem it is shut down. The pilot can eject from the stage in an emergency." So why put him there in the first place? If the computers are good enough to prevent the rocket exploding (which I most sincerely doubt) they are for sure good enough to take Stage One up vertically, down vertically, and land it. Further, the human pilot could not see the ground directly (look at the shape of the vehicle) so he would be depending on the computer in any case. No, he is 100% redundant; really he's just a liability. And man-rating Stage One would also cost a fortune— another couple of billion?

I could go one. However, more generally, the idea that reusability equals cheapness is an article of faith by those who like the idea of reusable launch vehicles (RLV), but it is just not born out by reality.

The unpalatable truth for these people is that until there is an EXISTING demand for several flights to LEO per week or even per day, expendable launch vehicles (ELV) will always be cheaper.

There are several reasons for this, and I could expand on this theme for days, but in summary here are a couple of the main ones:

(1) ELVs cost much less than RLVs to design, develop and build because they do not have to be used again. Throwaway goods in everyday life often are cheaper to use than reusable equivalents for the same reason.

(2) ELVs do not have to be brought back down, so they are much less complex than RLVs and don't require fancy reentry systems.

The basic, vital thing to remember is that the purpose of all these plans and projects is to drastically reduce the cost of getting to orbit. Everything else is secondary and unimportant. If the cheapest way was to fly there on a chariot pulled by geese, then so be it.

And in fact with today's knowledge the rational way to go is to build a large, expandable launch system to be used for cargo only; ideally something like Bob Truax's Sea Dragon Big Dumb Booster, but if not that, then you could do worse than rebuilding Saturn V, which nowadays could deliver 130 tons to LEO for lass than $500/lb. Being cargo only, it would not have to be man-rated, which cuts costs in half right away. Being expendable does the same again.

But really it does not matter what expendable vehicle is chosen; I would not object to an all solids vehicle if that were the cheapest. I don't care what the Isp is; I don't care what the mass ratio is. All I care about is getting the stuff up there as cheaply as possible. And that assuredly is not by way of a semi-SSTO RLV.

To get a better understanding of where I'm coming from, I strongly recommend you get hold of the book 'LEO on the Cheap' by Lt Col John R London III. Truly, it is an eye-opener.

dicktice · 2004-04-11 13:41:04

I'm leaning towards straight-up launching Mars expedition intentioned hardware to geostationary orbit, and using remote presence robotics to do the work in orbit, with the help of virtual reality visualization by the robot operators on Earth. Nothing returned, and the cargo keeps accumulating on a just-in-time basis. When the spacecraft is ready, the robots go along with it as astronaut substitutes. Communications time delay increases with distance, would be accomodated by previewing activities of the robots via virtual reality before carrying out each team activity, scenewise, scene by scene. Fuel constituents manufactured from water-ice cargo, en route. Vertical letdown to a tail-first powered landing on Mars. Assembly and expedition activities, likewise by means of adaptable robot teamwork, including extensive excavating, sample taking and onsite analyses. Nothing is returned from Mars. Meanwhile preparations for Expedition Two continue in geostationary orbit (robotic as well, with humans aboard if feasible--if not, on a later expedition). Launching cost estimation is beyond me, but surely the fuel saved--by not accelerating to LEO speed--would be available for single-stage-to-GEO launches, culminating with zero relative orbital velocity.

JimM · 2004-04-11 15:16:56

"…surely the fuel saved--by not accelerating to LEO speed--would be available for single-stage-to-GEO launches, culminating with zero relative orbital velocity."

Nope. I don't have the time or inclination to post an entire tutorial on orbital mechanics here, but the theoretical net gain from your proposal would be zero; in real life more probably considerably less than zero.In other words, a net loss.

I think your question is based on a misconception, which is that a satellite in GEO is stationary. But it is not, it is orbiting at exactly such a velocity that is keeps pace with the surface of the earth approximately 5.6 earth radii below it.

So here goes:

The orbital velocity of a circular orbit is related to distance from the center of the Earth by:

V = \sqrt{\frac{\mu}{r}}

Where \mu is the gravitational parameter and is 398,600 km^3/sec^2 for Earth.

In low Earth orbit, roughly 200km (=6578km to center of the Earth), the orbital velocity is ~7.8km/sec

In geo-synch (6.6 Earth Radii ~= 42100 km), the orbital velocity is ~=3.1 km/sec

The most energy efficient way to transfer to another orbit is typically a Hohmann transfer (http://liftoff.msfc.nasa.gov/academy/ro … hmann.html)

The semimajor axis of the transfer ellipse is: \frac{r_{LEO} + r_{GEO}}{2}, ~24250km

The velocity at any point on the ellipse (the above is merely a special case where a = r) is: V = \sqrt{\mu(\frac{2}{r}-\frac{1}{a})}

The velocity in LEO to get into the transfer ellipse (with LEO for r and trans for a) works out to ~10.4 km/sec

The velocity of the transfer ellipse when it gets to GEO (GEO for r and trans for a) is ~1.6km/sec

The delta V needed is obtained by finding the magnitude of the change in each spot.

3.1 - 1.6 + 10.4 - 7.8 km/sec = 4.1 km/sec delta V

Hope that makes the situation clearer.

RocketCo · 2004-04-11 16:56:58

Author’s reply;

(1) 'Build it and they (customers) will come' has already been tried. It's called 'Shuttle'. They did not come.

1. The Shuttle was a government program and was never aimed at making money.

(2) Don't forget NASA promised Shuttle would deliver payload to LEO for $60/lb. The actual true cost is a closely guarded NASA secret, but it's certainly well over $10,000/lb and may be as much as $20,000/lb. (That's why it's a secret.)

2. In the book the Company sells launch vehicles at $250,000,000 a pop. As will be discussed in the epilog it takes ten years of operating the vehicles at a loss to get to low cost transportation.

(3) In that light, TRC's promise of $200/lb to orbit (which, allowing for inflation, is just about the same as NASA’s $60/lb promise) must be taken with a gigantic pinch of salt. In the first place, it represents a price reduction from the real-life Shuttle cost of between 50 and 100-fold. The very best achieved today, by the Russians and ESA, is around $4,000 to $5,000— and these are not manned vehicles. But TRC promises a manned vehicle that's 20 to 25 times cheaper. Yeh, right. If I were you, I'd not be holding my breath.

3. We know that cost of many products has fallen dramatically over time if there is no fundamental reason why they can’t. The Saturn V used 22 lb of propellent per pound to orbit. Or about $5 a pound. That said no one knows how the possibility of low cost space transportation, will be achieved. The point of the book is to say; sell the vehicle not the services and used no new exotic technology in the vehicle.

(4) What's more, the additional cost of man-rating a vehicle has been disregarded in all this, but you can generally assume it will increase design and build cost by at least 100%.

4. For a reusable it does not cost more because the reliability is need anyway.

(5) What's yet more is the additional cost of design and build to make a vehicle re-usable rather than expendable is also ignored. Another 100% on top again, please.

5. The development cost is set at $3-7,000,000,000 about that of a new jet transport. The technology proposed is less complex than a jet airliner and the vehicle is a lot smaller. The Falcon V under development by Space-X has twice the payload at a cost of $12,000,000 vs $250 million for the DH-1.

(6) What on earth is the point of a pilot in Stage One? I thought elevator operators had died out as a breed some time back. With its straight up, straight down flight path, I doubt it would take even a particularly expensive computer to do the job— say one of today’s laptops?

6. A pilot will make the stage more reliable and in the long run a piloted stage is going to be easier to license for launch near population centers.

(7) There is also no word about flying Stage Two in unmanned mode. But this is vital. As we have learned from the history of Shuttle it is clear that risking men on missions that don’t need men, such as delivering cargo pure and simple, is almost criminal. That’s apart from the obvious fact that an unmanned version could deliver more payload to orbit.

7. Unmanned aircraft are less reliable, unmanned space vehicles more so.

(8) Flying Stage One straight up and down again is an amusing notion, but an exceptionally inefficient way to get the payload into orbit. Existing launch vehicles follow the trajectory they do not for fun but because it is significantly more effective than this proposal. But what about recovering Stage One?……

8. The DH-1 is not a missile where max payload/min wt is important, for the DH-1 nothing matters but overall cost. The DH-1 losses only about 30-40% of it payload by flying the trajectory which is optimized for ease of recover of the first stage. The vehicle should not be compared to a optimized two stage but to a single stage. It has better payload and lower development cost than a single stage but retains much of the simplicity of operation of that of a single stage.

(9) Don’t bother recovering Stage One. By making it expendable a fortune would be saved, as it would not have to be built for reuse. Recovering and refurbishing the Shuttle’s solid rocket boosters almost certainly costs more than letting them sink and building new ones. Which leads naturally to…

9. The first stage is very simple and would need little or no refurbishment between flights. An expandable stages of the same size will cost 2-5 million even from a company like Space-X and of course if it is maned rated it will cost a lot more. An expendable stage also does not fit the proposed marketing plan.

(10) Recoverable launch systems (RLS) will only become cheaper than expendable launch systems (ELS) when there is far more traffic than today. And as already pointed out, there is absolutely no assurance that low cost to LEO will deliver more business in a short enough time to prevent the RLS makers going bust in the meantime. If NASA had not been a government agency, I think it’s clear that Shuttle would have bankrupted them long ago.

10. I have to agree, for a RLV to be economical there must be a lot more traffic, but there must be a lot lower launch cost in order to get more traffic. It is a classic chicken and egg problem. The book presents one proposed solution to the problem. The market for a maned RLV might be different than the market for launch services, and if a number were sold, the market of services would grow.

(11) No-one should ever forget that today we have the absurd situation where sending a given payload to LEO by Shuttle costs several time more than it did using Saturn (in constant dollars) over a third of a century ago. Since the instruction to the Saturn engineers was to get the thing to work never mind the cost, and the Shuttle was justified almost solely on the basis of its cheapness compared with expendable systems, it’s abject failure is clear to all to see, or should be.

11. The situation today is hard to understand and it is not just the US and NASA that have problems nobody has found a low cost solution to the problem of space launch. The book is an attempt to look at the reasons why space transportation costs have not fallen very far and proposes a possible solution. More importantly the aim is to educate, and perhaps contribute to better design solutions in the future. No more NASP or X-33 or Buran, billions spent with no results.

(12) Certainly the day must come when re-usable SSTO systems will be the way to go into space, but that day is most certainly not yet. What NASA ignored when lobbying for funds for Shuttle, and what people like TRC continue to ignore, is that at the present state of our technology, the cost of designing and building a re-usable vehicle makes such a so-called cheap system horrendously expensive. Indeed it is far more expensive than an expendable system in terms of the only measure that matters, which is cost per kilogram of payload to LEO.

12. The day is not yet, but the book argues it not the technology the is postponing the day, it is pursuing the wrong markets and wrong technology that give space launch a bad name. It is certainty true that a reusable vehicle is not cheaper unless the market for launch services is large maybe 10-1000 times larger than existing markets. The book tries to show one way that it might be possible to drive down launch cost with out a large transportation market, by selling launch vehicles. Only about 5% about of fiber optic cable band width was in uses in 2001. It may have made no senses to build so much bandwidth, but the fibers networks were built and cost for bandwidth are falling and demand is growing.

Something like that is need for space transportation.

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Re: Low-cost-reusable vehicle design-FICTION - possible to actually do this today?

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