Lots of good stuff over there today. Jeff Foust got an interview with Burt Rutan. I'm not surprised that the accident has caused a delay in engine development (I'd have been surprised if it hadn't). I am surprised to hear that they're considering going away from nitrous. What are the other options, if they want to continue to use a hybrid (whose safety Alex Tai continues to tout, a little too much I think)? Peroxide? LOX? They have their problems, too. I wonder if they'll finally consider releasing control, and giving the work to a propulsion subcontractor that knows what it's doing (e.g., XCOR, though that would mean a liquid, not a hybrid, since they have no interest in or experience with hybrids).

On other topics, there's an interesting article about the V-Prize, a concept that was new to me:

The types of aircraft capable of crossing the Atlantic in less than one hour will have rocket engines. Their average speed will be greater than 6,000 km/h and their maximum speed will reach Mach 15 or even Mach 20. “They will take off like space launchers, follow a ballistic trajectory like intercontinental missiles, reach an altitude of 100 to 200 kilometers and then land like gliders. At the height of the trajectory, the pilot will experience several minutes of weightlessness, then be subjected to accelerations of eight, nine or even ten g at the moment of re-entry into the Earth’s atmosphere, depending on the particular shape of the trajectory,” said Christophe Bonnal, a senior expert at the French space agency CNES.

While this is a suborbital flight, it's a very high-energy one. It will need thermal protection systems for entry similar to those needed for an orbital entry, and good mass fractions on the vehicle. I'll be interested in seeing the rules. Will it require a turnaround of the same vehicle for a second flight, as the X-Prize did? If so, how will they ferry it? Will two-stage systems be allowed? I think it's a good idea in concept, but I'm skeptical that it can be done by 2013. If it can, though, orbital capability wouldn't be far behind.

Taylor Dinerman writes about half a century of ICBMs (the technology that got us to the moon quickly, but off on the wrong foot entirely when it comes to affordable and routine space access).

And Nader Elhefnawy discusses the potential for a resource-based space program.

considering that X-Prize was just barely won, with just one serious entrant, others lagging years behind and that there have been no suborbital space flights at all since then and there wont be any in near future, the V-Prize is likely shooting too high too soon.

What do you mean by "near future"? I'll be quite surprised if (e.g.) Armadillo isn't doing suborbital flights within a couple years.

Armadillo, maybe, but they are about the only ones. You do remember, that Armadillo was considered close to suborbital at the time when X-Prize was won as well, and its now been a couple of years ..

By near future, i meant within a year or so. It does not look like anyone will fly a manned suborbital across the 100km boundary in 2007/08 right now, unless there is a dark horse in the running.

Maybe there will be some in 09. Getting from up and down experimental suborbital to across the atlantic manned hops in four years seems like too little time to me, considering the tempo of advancement so far.

I'd like to be wrong, of course, and it would be real nice if this prize would not have expiry date at all, and if there were second and third place prizes as well.

I suspect a skip trajectory would be better for that hypothetical transatlantic rocketplane rather than a near-orbital ballistic trajectory.

I agree, Paul. Again, I wonder if the rules will require ballistic, or just that it do it in an hour?

I really hope they do this. I know many people will say it is unrealistic, etc - but people said that about the X-prize, too. These things really work - at the very least they raise the excitement level!

At sufficiently high flight rates, suborbital rocket transport operators will have to worry about pollution of the stratosphere. Water injection, in particular, may be a limit. The current water flow into the stratosphere is on the order of hundreds of megatons per year, which is similar to the total water vapor released by current airline traffic (most of that goes into the troposphere, though, I believe).

It may end up that rockets using CO/O2 would be prefered, since the stratosphere, particularly at higher altitudes, contains much more CO2 than water (and if you extract CO2 from the troposphere to compensate, the system can avoid any contribution to longterm CO2 increase). I tried pointing out this advantage of carbonaceous over pure hydrogen fuels to our dear Mr. Elifritz a few years back, and got a rather negative reaction. :)

Sane comments to Elifritz rarely get a positive reaction.

How viable are these skip trajectories really? What L/D are we talking about at such speeds? Or what kind of leading edge heating?

The first IRBM:s had single stages, high mass ratios, ISP of about 250 s leading to an ideal delta vee of about 5 km/s, and still only had a range of less than 3000 km.
From New York to Paris it's 6000 km.

I think the V-prize folks are very seriously underestimating the engineering challenge. "Hey, it's just a bit more than a SpaceshipOne." But probably none of that figures in to the suit types' fantasies.

Wonder if they will limit it to rockets or allow other entries. This is only half the time (1 hr 56 miles) it took the SR-71 to cross from NY to London in 1974. A Mach 5 business jet would be much more useful commercially then a sub-orbital rocket. And much more likely given the state of the alt.space industry - although a Falcon 9 and Dragon, if built, could do it.

"“If you had told me [in 1967] that the performance forty years later of military fighters would be the same, it would have been totally nonsensical,” he said."

It's totally nonsensical now, unless you consider the F-35 and F-22 to have the same performance as military fighters from the 1960s and 1970s!

"Rutan noted that NASA made an “enormous amount of progress” in the 1960s and 1970s by creating a series of vehicles to take people into orbit and the Moon, and then developing the shuttle. Since then, though, there’s been little progress in Rutan’s eyes..."

Yes, and there's also been little funding. Let's not forget just how much Mercury/Gemini/Apollo cost.

I'd stick a tiny capsule on top of a two stage rocket if someone asked me what was the easiest way to accomplish this. :)
No scramjets or other headaches.

Using rockets to make suborbital passenger flights around the world was a staple of many great Robert Heinlein novels. It would be awesome if someone could say that they are taking the noon rocket to London, but they'll be back for dinner in New York by eight. It might even make up for not having flying cars by now.

Viewed that way, the Starchaser people might have the best shot at it...

maybe they should try a shorter distance for starters .. like, say, northern Germany to London .. er, wait ..

Actually, densityduck,
someone might think some modern aircraft are not so advanced after all. ;) ;)

"“If you had told me [in 1967] that the performance forty years later of military fighters would be the same, it would have been totally nonsensical,” he said."

It's totally nonsensical now, unless you consider the F-35 and F-22 to have the same performance as military fighters from the 1960s and 1970s!

There are many measures of aircraft performance. If all you're looking at are parameters like top speed, service ceiling, range, etc., then it is apparent that today's fighters aren't performing any better than those of the 1960s. However, if you look at other paramters that factor into operational effectiveness, then today's planes are much, much better. Some of these parameters include sustained G loads, weapons accuracy, radar cross section, system performance (radar, navigation, engine power and reliability, etc).

Look at the top US fighters of the 1960s and today. That would be the F-4 Phantom II verses the F-22 Raptor. In terms of combat ability, the Raptor would eat the Phantom's lunch. With its stealth and long range missiles, the Raptor could easily destroy the Phantom before the Phantom even knew it was there. If they got close enough to rumble one on one, the Raptor has much higher maneuverability, better missiles, and a better gun (an afterthought on the Phantom). The Raptor could also find it much easier to penetrate defended airspace to bomb a target.

You can go down the line and compare virtually any of the 1960s fighters against their modern counterparts and come to similar conclusions. Sure, the speeds have not increased but the capability has and that's what really matters.

As as aside to mz, could you please post that article hyperlink as text? When I opened it in the comments window, it was hard to read because the window is too small and I can't resize it.

sure,
http://www.ausairpower.net/Analysis-JSF-Thud-2004.html
(you can click mouse2 and copy address with firefox, with opera you can middleclick to open in a new tab).

It's just a piece by an australian defence analyst which says that JSF is really a strike craft in the Thud vein (F-105) and not a fighter, and thus not suitable for Australia, who needs top air superiority fighters against all the neighbours' new Sukhois. (And F-111s for long range strike.)

Thanks for the link. I've skimmed the article and found he made some rather glaring mistakes when comparing the F-105 to the F-35. First, he admits the F-35 has more wing area. He completely fails to mention it's thrust to weight ratio advantage. According to this article, the F-105 had a thrust to weight ratio of 0.74 and a wing loading of 93 lb/square foot. According to the numbers in this article, the F-35 has a full fuel thrust to weight ratio of 0.968 (1.22 with 50% fuel) and a wing loading of 91.4 lb/square foot. If those numbers are accurate, the F-35 would be a much more maneuverable plane.

He's really doing an apples-to-oranges comparison, anyway. He's claiming that the JSF isn't an air superiority fighter and he's right! The JSF stands for "Joint Strike Fighter". It wasn't designed to be an air superiority fighter. What Australia needs to consider is what type of aircraft best meet their projected needs over the next few decades. Do they need a plane like the F-22 with great air superiority capability (and great cost) that can drop a couple bombs, or do they need a strike aircraft that can also defend itself?

Yeah, it's a bit of a stretch but the logic of the comparison is clear - Thuds could not defend themselves against Migs and needed Phantom support (the synonyme is questionable content!) - same could be with JSF:s, they would need F-22:s to protect against the Su-27 derivatives. The JSF is slow and has little fuel so it really is a sitting duck against the Sukhoi.
Stealth and maneuverability help the JSF, but the Thud had some advantages compared to Migs too and still needed support.

It might be a nice cost effective plane for bombing in third world countries, but not for the needs of Australia's home defence.

Don't underestimate the challenges of shooting down a plane you can't see. Stealth is a big effectiveness multiplier. The Su-30 is an amazing plane but it's far from stealthy (meaning it can be seen) and can't do much against a stealthy platform.

Air superiority fighters are great for clearing the sky of enemy planes. However, they're pretty limited in being able to do other things. That's why the F-15C isn't being used very much in Iraq or Afghanistan. Fighers that have an air-to-air capability with an solid air-to-ground capability (e.g. F-15E, F-16, F-18) are much more useful in more situations than a pure air superiority fighter like the F-15C.

Australia will make their decisions based on their particular needs. Given the relatively small size of their highly professional and skilled military, they may opt for planes that are multi-role like the JSF because they offer greater flexibility and utility than single mission planes.

If you read the site more, it presents a good case of the as JSF a lose-lose option. It's slow and not very stealthy either, especially the downgraded export version. It also has low range.

It's the worst of both worlds.

The author argues that F-22 would be far better for air superiority (where JSF is next to useless, it has a sucky radar too) and the strikes could be done with the existing domestically maintained and domestically upgradeable fast F-111 aircraft. Total cost being less than buying a big amount of F-35 craft. (And they must buy Super Hornets in the mean time since JSF will take so long, adding cost more. Super Hornets are slow, short range and have bad radars too.)
Basically, the big distances in Australia's case favor bigger aircraft.
But it's not an area where I'm an expert, just that it seems a pretty well presented case for me.

http://www.ausairpower.net/jsf.html