Reader's Favorites
Media Casualties Mount

Administration Split On Europe Invasion

Administration In Crisis Over Burgeoning Quagmire

Congress Concerned About Diversion From War On Japan

Pot, Kettle On Line Two...

Allies Seize Paris

The Natural

Gore Book Sales Tank, Supporters Claim Unfair Tactics

Satan Files Lack Of Defamation Suit

Why This Blog Bores People With Space Stuff

A New Beginning

My Hit Parade
Instapundit (Glenn Reynolds)
Tim Blair
James Lileks Bleats
Virginia Postrel
Kausfiles
Winds Of Change (Joe Katzman)
Little Green Footballs (Charles Johnson)
Samizdata
Eject Eject Eject (Bill Whittle)

Space
Alan Boyle (MSNBC)
Space Politics (Jeff Foust)
Space Transport News (Clark Lindsey)
NASA Watch
NASA Space Flight
Hobby Space
A Voyage To Arcturus (Jay Manifold)
Dispatches From The Final Frontier (Michael Belfiore)
Personal Spaceflight (Jeff Foust)
Mars Blog
The Flame Trench (Florida Today)
Space Cynic
Rocket Forge (Michael Mealing)
COTS Watch (Michael Mealing)
Curmudgeon's Corner (Mark Whittington)
Selenian Boondocks
Tales of the Heliosphere
Out Of The Cradle
Space For Commerce (Brian Dunbar)
True Anomaly
Kevin Parkin
The Speculist (Phil Bowermaster)
Spacecraft (Chris Hall)
Space Pragmatism (Dan Schrimpsher)
Eternal Golden Braid (Fred Kiesche)
Carried Away (Dan Schmelzer)
Laughing Wolf (C. Blake Powers)
Chair Force Engineer (Air Force Procurement)
Spacearium
Saturn Follies
JesusPhreaks (Scott Bell)

Biting Commentary about Infinity, and Beyond!

« Wings Or Not--Who Cares? | Main | The Floodgates Open »

In Search Of Intelligent Reporting

There was a skeptical article about suborbital flight in the Independent, yesterday. There's much to fisk here.

Going suborbital is like firing a cannonball into the sky and waiting for it to come back down again. It requires speeds of only about 2,500mph, and is the equivalent in terms of distance to going from Watford to Birmingham and back again. True orbital space travel - when you accelerate fast enough to fly continually above the Earth's surface - can only be achieved if the space vehicle reaches 17,000mph.

The problem is that there is no halfway house - you are either in suborbital flight or true space orbit.

I don't understand what this statement means. What kind of "halfway house" is the reporter seeking? What are its characteristics? And what is it that's "true" about a "space orbit"? Is he saying that if it's not in orbit, it's not worth doing, or not in space?

This whole bit is quite misleading, because it implies that suborbital is slow, and orbital is fast. But the 2500 mph is just a minimum (and a good place to start, given our paucity of experience). Velocities all the way up to 16,999 mph can also be suborbital. In fact, one can go faster than orbital velocity and still be suborbital, if pointed the right way (that is you include in the definition of suborbital those orbits that intersect the earth's surface...).

And if you reach orbit, there is the complex and dangerous issue of re-entry into the Earth's atmosphere, with all the friction and heat this generates - a phenomenon that led ultimately to the disintegration of the Columbia shuttle.

Entry isn't a problem unique to orbit. It's a problem for suborbital as well. After all, if you enter space, you have to leave it. The difference is that by starting in small suborbits, where the entry is relatively benign, we can gain experience with techniques and materials, and gradually increase the entry velocities, expanding our operational envelope until we can do it from full orbital velocities.

But the folks interviewed here don't get it, so neither does the reporter.

Ellis says that a prize for a suborbital flight does little, if anything, to foster true orbital space travel. "It's like being in the early 19th century and someone says, 'Well, I'm sure one day someone will get to the South Pole, here's a million-dollar prize for someone to go to the equator.' Getting into space cheaply - genuinely into space, that is - is a very different thing."

Alan Bond, the British rocket engineer who was the brains behind the ill-fated but revolutionary Hotol (horizontal take-off and landing) rocket engine, is equally scathing about the claims being made for the X-prize. "It's very fringe, and in particular it is potentially dangerous. On paper you can lash up a rocket and get the prize, provided you can cut out the safety measures. But it is putting lives at risk for no possible gain," says Bond, who now runs an Oxfordshire-based company called Reaction Engines...

...More important, Bond wonders, what would be the point of a suborbital flight lasting no more than 10 or 15 minutes? "Trips round the lighthouse have been popular for a number of years," he says, but they serve no purpose other than amusement for people with money to spend.

Yes, poo poo. We can't be bothered with that piddly suborbital stuff. We have much more important uses for the money.

And what's the point? So what if people are willing to spend their own money to go into space? They aren't going for reasons that I think are good, so it's a waste of money.

A little background is in order here.

Alan Bond is a British engineer, one of the technology uber alles types, who believes that launch is expensive because we just haven't funded the right concept (his, naturally). He has spent much of the past couple decades attempting to talk Her Majesty's Government into parting with the funding needed to develop his airbreathing launch concept, which he believes holds the key to universe.

He can't be bothered with all of this silly suborbital stuff, or the foolish dotcommers who would waste their money on it when they could be funding his project instead.

"Ellis" is Richard Ellis, a former Cambridge professor of astronomy now at Cal Tech. Let us put aside for the moment the nonsensical notion that a professor of astronomy would have any particularly useful insights into rocketry, or business--it apparently arises from the confusion between astronomy and astronautical engineering on the part of lay people, including journalists (hint, they've very little in common). Instead, just read this little vignette from earlier in the article:

Caltech was courting Bezos because it was looking for financial sponsors for its new, ground-based telescope. After a tour of some of JPL's research projects, the party sat down to lunch. Bezos had brought along a few of his employees from Blue Origin, as well as the science-fiction writer Neal Stephenson, a close friend and confidant of the internet billionaire.

Over lunch, the Caltech scientists realised that their dreams of receiving a large cheque for their new telescope were not to be. "It became obvious that Blue Origin was where Bezos was putting his money," recalls Richard Ellis, a Caltech scientist and a former professor of astronomy at Cambridge University.

Sure, he's a great unbiased source for opinions on the validity of these ventures...

The naysaying goes on to the end of the article:

But one cannot help but feel that the very rich men behind the private push to send people into space are not all in it for the benefit of humankind. As Richard Ellis says: "These guys have lots of money to spend, and they seem to be having fun."

When he met Jeff Bezos, he came away with the distinct impression that the Amazon boss was having fun also with the idea of space tourism. "But I have to say I just didn't see any evidence that Bezos and Blue Origin had an idea." It will take more than a rich man's intellectual distraction to get fare-paying passengers into space - and safely back again.

Well, I can't say whether or not Blue Origin has a solid plan or not--they've been extremely secretive, but there are certainly a number of other companies that "have ideas," and they're implementing them, regardless of the blinkered views of frustrated astronomers and propulsion geeks.

It's a shame that the reporter, Steve Connor, never bothered to interview anyone who actually understood the technical, economic and business issues.

Posted by Rand Simberg at August 06, 2003 04:34 PM

Comments

Was 90% of the article supposed to be a link?

Posted by Jeff Dougherty at August 6, 2003 04:39 PM

No, I fixed that...

Posted by Rand Simberg at August 6, 2003 04:50 PM

Having suborbital flights before orbital flights was good enough for NASA, and as we all know, everything NASA does is the right way to do it, so what's the problem? (Other than that it's taken forty years for people to follow in NASA's footsteps...)

Posted by Raoul Ortega at August 6, 2003 07:19 PM

A hundred years ago that article would have been about the folly of trying to perfect heavier-than-air atmospheric flight.

Posted by Kevin McGehee at August 7, 2003 07:28 AM

We can actually look at this the opposite way. Sub-orbital might be the actual 'key' we are looking for - if - we can find a way for a suborbital craft to deliver a sufficient payload to a craft passing by at orbital velocities. It's like breaking the system into two - one system stays in orbit - at orbital velocities - while a second system just pops up and passes the baton. It's kind of like the ESA Hopper - it gets the second stage going at a good clip - not quite orbital and gets it above the atmosphere.

Thus, perhaps all that is needed is the interface or link to effectively pass decent cargo from a slow ship at altitude to a fast one at the same altitude - Any thoughts?

The Tether system I think was something of an interface between the two - right?

Perhaps a large electric rail gun to shoot basic payloads up to speed?

Posted by Chris Eldridge at August 7, 2003 08:01 AM

I like the tether idea and would like to see it implemented asn one of many rungs to help orbital access.

The idea I thought the most practical was Robert Zubrin's. Basically create a space plane that uses Kerosine for fuel and which can refuel from a standard military refueling plane when it gets to high altitudes. You get less bang using Kerosine but its easier to handle and thus far more practical in a number of ways.

I think practical answers are more likely to provide cheap answers than pie-in-the-sky hail-mary attempts at technological breakthroughs.

Posted by ruprecht at August 7, 2003 08:53 AM

Typical,pompous,intellectual blowhards with a big case of Sour Grapes. It also looks like the writer lifted alot of stuff from the July Wired magazine article (or at least used it for his "research". The Big difference is that Wired at least tied to stay a little more neutral to positive, of course Wired likes Rich guys who are trying to do things different.

I should have just stuck with reading Rand's commentary. Instead of reading that article, I could have done something more useful with my time like playing M$ solitaire, or picking my nose.

Posted by William at August 7, 2003 09:40 AM

>pie-in-the-sky hail-mary attempts at technological breakthroughs

I love this! It's always great when you get a breakthrough like that unexpectedly, but it really isn't needed. As rand always says (THE fundamental design principle) you need to know what you want to do before you build a system to do it. Once you know that, its all how you break apart your requirements into specific designs: The planetary society is (I think as a lot of us have) recomending breaking apart human launch from Cargo Launch. This is what I mean by identifying requirements and breaking them up: like using Soyuz to launch people and Proton to launch cargo!

In this vien the idea of using suborbital craft to get you halfway there is a further breakdown
of your requirements: provided we can find an effective interface to pass the baton.

Posted by Chris Eldridge at August 7, 2003 09:45 AM

Gee, it's too bad that Bezos is "having fun" with his own money. Since before I saw the first moon landing, going into space was very important to me, and I had NO doubt that it would be common by now. After all, look how far air travel had gone in that time, and look how fast we got to the moon from our first small steps. But I have completely given up on NASA. If I had the money, I would be doing EXACTLY what Bezos is, and would love every minute of it. He, Rutan, and the other commercial types have given me hope I'll get there after all, DESPITE how much government idiots have screwed up. Suborbital? OF COURSE! One of the big problems with the present hardware is that they jumped too far, too fast. Going to the moon, and even orbit was a "Manhattan project" scheme: Big. Powerful. Fast. But also very expensive and very crude. Suborbital is the way to start (incidentally, X-15 would have gone that route if not cancelled). And a lot of non-techies aren't going to mind the technical difference between orbital and non-orbital space flight, they'll just love to GET THERE.

Posted by VR at August 7, 2003 03:31 PM

The other thing these folks who are down on suborbital miss is that the suborbital market will quickly prove the orbital market. And then all kinds of traffic will bear...

Posted by Andrew at August 8, 2003 10:36 AM

I just wanted to take a second to let you know what I meant by electric rail gun. Rail guns use an electric pulse to push a projectile down a tube at orbital speeds 17-25,000mph. Possible because the electric pulse can move much faster than expanding explosive gasses. There is no recoil.

In space applications (in the future of course) perhaps we could build a Hypersonic SST like craft able to get close to the limits of space, but no where near orbital velocities. From there, an electric rail gun running down the length of the aircraft’s fuselage could fire off 100lbs pound canisters of water and other basic supplies up to a passing spacecraft in orbit. After firing off 20,000 pounds of cargo from a holding pattern above its landing area, it would return without the need for tremendous heat shielding. The technology here ‘is’ of the ‘hail marry’ type, but not unthinkable - perhaps even a bit more attemptable than a Tether??? Not sure. The next generation of Tanks may themselves feature electric railguns.

It breaks the system needs into 'three' components - Spacecraft (ever remaining in orbit), Launch Platform (SST), and an Electrically Propelled projectle! Finding a way to use 'electricity' in the launch process is great because it is not a weighty propellent and can be obtained freely in space.

Future space stations too could be a rail gun platform to further boost payloads to hire and hire orbits!

Posted by Chris Eldridge at August 8, 2003 12:33 PM

Perhaps we should just launch spaceplanes from Quito Equador which is along the equator and at high altitude (9,500 ft) and not far from a reasonable seaport connected by rail. We could even run a railgun up Mt Cotopaxi (19,384 ft) to launch unmanned cargo rockets sort of like a recoiless rifle to space. It also has nearly unpopulated areas to the east in case of an accident.

Someone just needs to talk to the Equadorian government.

Posted by ruprecht at August 8, 2003 01:12 PM

Hope this is not too off topic, but I was wondering about this "suborbital has nothing to do with spaceflight" mentality. If an X-Prize seeking company like Armadillo Aerospace creates a single-stage vertical take off craft, wouldn't that be useful in a number of in-space applications such as an orbital transfer vehicle or even a lunar-lander? Seems like their design wouldn't have to be altered too much to be able to be used in such a fashion.

Posted by B.Brewer at August 8, 2003 04:54 PM

Rail guns use an electric pulse to push a projectile down a tube at orbital speeds 17-25,000mph.

Uh, no. I've heard of speeds around 4 km/s being achieved (with the power source providing six or seven million Amps), but at the moment gas guns (using fuel/air explosions to drive the projectile) still obtain much higher velocities. Rail guns like to disassemble themselves due to electromagnetic forces at high energies, too, so they are either very massive or one-shot devices (with shrapnel).

There is no recoil.

A gentleman by the name of Sir Isaac would like a word with you... Seriously, rail guns have a recoil -- conservation of energy and momentum still applies. It may not be as high as with an "explosive" gun, but it's still there.

Finding a way to use 'electricity' in the launch process is great because it is not a weighty propellent and can be obtained freely in space.

The electrons and the electric fields moving them may be very low-mass, but the storage of all that energy isn't trivial... nor light. This is the big problem with electric cars, remember? Also, the flighttime of the sort of vehicle you've proposed is far, far too short for it to gather the requisite energy, even allowing for 100% conversion of the relatively low-density energy of sunlight.

That's three strikes... ;)

Posted by Troy at August 8, 2003 10:41 PM

The 'recoil' would be spread out over the entire length of the accelerator instead of inside a several foot artillery tube. If a magnet pushes the object forward, the object pushes the magnet backwards.

Posted by Mike Puckett at August 9, 2003 07:59 AM

Troy,
The storage of energy (if indeed batteries were being used) would be heavy. In order for the army to get a rail gun into a modern tank what they are thinking is novel. They want to use one of those 100,000 RPM spinning/levetated devices where a mass is suspended in an electric field and spun. It provides the quick discharge when needed and the turbin motor of the tank gets it back up to speed to sustain a rate of fire equivalent to modern tanks. No doubte heavy but more effective than batteries.

I'll double check on the 17,000 - 25,000 mph speeds I mentioned. It was what I remembered from a military book. Projectles at such speeds from a "rail gun rifle" that a soldure would carry, was said to be enough for a single soldure to defeat a tank's armor: much like a spec of paint at 17,000 mph can do damage to an orbiter.

A tether system, Ion engine, and rail gun are ways to introduce electricity into the launch process. Finding a way to pass the baton from suborbital to an orbital vehicle may be the key to inexpensive space flight.

Posted by Chris Eldridge at August 11, 2003 06:57 AM

Chris, I think you're barking up the wrong tree with rail guns. The current densities necessary to reach speeds over ~4 km/s are such that they vaporize portions of the rails and the projectile; this is an unavoidable side effect of the technology, which requires a conducting loop (at higher velocities, plasma from the vaporizing components forms part of the circuit, BTW -- which is why it still works at all).

I understand that you're not limited to batteries (the capacitors would be heavier yet), but with your proposed system the logical question is this: is such a storage device, pumped by turbines, more efficient than rockets burning the same fuels? I think you're going to lose with multiple layers of inefficiency... it works with ground-bound tanks, maybe, but spacecraft are a different animal.

Posted by Troy at August 11, 2003 12:11 PM

Troy,
Went digging for my article snippets and have information about rail guns and gas guns. The figures seem to fall somewhere in-between what you and I talked about:

The University of Texas was developing the Tank Rail Gun. Its original test bed weighed 25 tons (gun and all) but was expected to shed one half to five times this weight in development. The original gun barrel was 30ft long. It fired projectiles at 9,000 mph at a rate of three rounds a minute. A second (newer) article on the same project stated “the force can accelerate metal projectiles mounted on electricity conducting rails to speeds of at least 10km per second!” “Firing a single tank bullet requires a brief surge of current equivalent to the output of several nuclear power plants.” “The secret was trading bulky capacitors for a ‘flywheel’ (an eight foot long cylinder of composite material spinning at about 10,000 rpm.” The flywheel can be brought back up to speed in 20 seconds. The tank gun was expected to be ready 2010.

Sandia National Labs has a ‘Coil Gun.’ It is like a rail gun but the projectile is magnetically suspended inside the tube thus avoiding friction and barrel ware. At the time of writing (5-8 years ago?) it was firing 7lbs projectiles at .316 km per second. A proposed 1000 meter version would propel 1000 lbs. projectiles fast enough from the ground to reach orbit with a small booster rocket. Sandia Labs also had a Gas Gun able to reach speeds of 27,000 mph.

Weapons Technology Directorate had a gas gun that could shoot a 15lbs projectile to Mack 8.

Lawrence Livermore Gas Gun: 11 lbs. at 9,000 mph and could place the projectiles 280 miles into the air.

A side not is that ‘EM Catapults’ are intended for the US Navy. They are able to launch 100,000 lbs. aircraft at 140 knots….

Not sure where this leads us…..If projectiles can only reach 9,000 mph, it would mean that the launch aircraft would have to make up the difference-flying at 8,000mph: presently unreachable: even for the Sanger SST!

Posted by Chris Eldridge at August 12, 2003 07:06 AM

Chris, just a few comments and then I'm done with this topic.

First, note that your figure of 9000 mph is in fact just about 4 km/s -- and this appears to be the practical limit for moderate masses (several kg, not tens or hundreds) fired from a rail gun.

Regardless of UT claims about a 10 km/s gun, they haven't done it to the best of my knowledge; the greatest velocity I'm aware of with a kg-range mass was 6 km/s, and portions of the rails and the projectile itself were vaporized in the shot. Sandia managed to get a much higher speed -- one report said 16 km/s (!) -- but this was with a tiny projectile, only a tenth of a gram... and the gun destroyed itself in the process of firing.

Plenty of claims have been made for rail gun performance, but the sort of thing you're projecting simply hasn't been achieved yet... and it may never be. This site gives a decent explanation:

When current is applied to the rails, a Lorentz force is created by the interaction of the armature current with the magnetic field of the rail current. This force accelerates the armature from the railgun breech towards the muzzle. The Lorentz force is proportional to the current squared. Hence, high currents are used to achieve high accelerations, resulting in high plasma temperatures. Consequently, the plasma armature ablates and accumulates material from the pellet and gun barrel. This increases inertial and viscous drag, lowering acceleration.

It's a power law you're fighting. Conductor resistance and material properties (vaporization temperatures and mechanical strength -- the Lorenz forces are huge, and tend to disassemble the gun) place fundamental limits on rail gun performance, enthusiastic supporters' opinions notwithstanding.

The link I gave discusses rail guns in movies; that's where most people's concept of the devices comes from, and it's simply not accurate. Perhaps someday the tech will be better, but for now the rail gun simply can't provide the performance you want, and changing that means developing materials which don't yet exist.

My apologies to Rand for using up more bandwidth and disk space; this is the last I'm going to post on the topic.

Posted by Troy at August 15, 2003 05:40 PM

Chris Eldridge wrote:
>Weapons Technology Directorate had a gas gun
>that could shoot a 15lbs projectile to Mach 8

Would that be the one at Eglin AFB? The one built from re-claimed parts and 'powered' by truck batteries? :o)

Randy

Posted by Randy Campbell at August 18, 2003 02:23 PM

Sorry, I missed the 'gas-gun' portion :o)

Actually there IS a Electromagnetic test gun at Egling that the Weapons Test directorate there DID build out of salvaged parts and truck batteries. At the time I last read about it, they were hitting M-2+ with the test shots and trying to convince the Air Force to let them extend it another 50 or so feet so they could test sub-orbital launch trajectories.
(The problem of course is Eglin is located on the Gulf coast of Florida and they would have been 'launching' over the main part of Florida. I dont think the Directorate would put up with that :o)

Randy

Posted by Randy Campbell at August 18, 2003 02:28 PM


Post a comment

Name:


Email Address:


URL:


Comments:


Remember info?