Leonard David has a report from Las Vegas on what Bob Bigelow is up to with inflatable space structures. I probably haven’t emphasized this activity enough. If SpaceX is successful, we will soon have a private space habitat testbed launched on a private launch vehicle.
So what
John Derbyshire has been asking questions about why frozen sperm survives freezing, and gets a knowledgable email on the subject. The emailer does understand the issues, except for this:
A good post-thaw viability (survival of cells) is around 60% of the total of cells– some people advertise >80% or 90-%, but that is a bit of a ‘lie via statistics’ game– they don’t count all the dead population in computing the percentage. We are working here with different, more efficacious, and non-toxic CPAs, of which the most promising appears to be arabinogalactin extracted from larch trees.
As you can see, this is the reason that we will never get Ted Williams back among the living. His frozen body consisting of billions of cells simply would not work with only ~60% of the cells surviving the thaw process. As one can say, God instills the soul when He wishes, and outsmarts us all.
This, of course, presumes that the only method we will have, now and forever, is crude thawing. It ignores the future possibility of different techniques for restoring the tissue to room temperature and viability (e.g., nanomachinery that repairs as it warms). It’s fair to have an opinion that we may never have such capability, but it’s quite foolish, I think, to believe categorically that this is so.
I noted a while ago that Kerry’s space policy sounded as though he wanted to return to the nineties. That may still be the case, but Jeff Foust says that there may be some new blood coming into his kitchen cabinet for space:
…one wonders if the briefing on SpaceShipOne may have influenced some of the language in the Kerry campaign’s technology policy released last month that advocates increased use of prizes by government agencies, mentioning the X Prize by name.
If so, a Kerry presidency might not be as disastrous for space policy as I previously feared. Which is not to say, of course, that I’ll vote for him.
Kevin Murphy has some thoughts about supersonics, based on my previous post. He’s skeptical.
Given that he’s not stooped to calling me a scientific lightweight, and incapable of understanding mathematics, that’s fine, but he doesn’t really understand the whole picture, which is understandable since I haven’t really presented it. This is a matter of some frustration to me, but one that I can do little about until I can persuade the company involved to put up information on the web, so that it can be critiqued and reviewed.
Regardless, I’ll try to respond to his comments as best I can under the circumstances (which include limited time on my part).
…even if you have the same drag coefficient at supersonic as you do at subsonic — your drag, and thus fuel consumption, will increase substantially.
The key clause here is “if you have the same drag coefficient at supersonic.” At least for the wing, it’s actually possible to do better, at least in terms of induced drag (an effect of the end of the wing, which makes it greater than two-dimensional) which is actually improved at higher speeds. The notion, right or wrong, postulates that supersonic L/D for aircraft designed under this theory will be similar to that of subsonic aircraft, so it offers the potential (if not promise) of airfares comparable to subsonic fares for the same routes.
With regard to his comments on angle of attack, they’re not relevant, because any angle of attack that is non-zero will dramatically increase wave drag and induce shock waves. The aircraft’s nominal design condition is zero AOA. Takeoff and time to cruise aren’t an issue, either (as isn’t the engine) because we can get rid of the extreme sweep that has always been associated with supersonic aircraft (a design strategem that was always a kludge to come up with a way of minimizing wave drag without solving the fundamental problem).
Something like the SR-71 engines are a likely solution, in terms of the inlet, but that’s not a problem because they’ll be optimized for fuel economy at cruise speed (which will constitute most of their operating time), not takeoff/landing. Also, we’re not proposing anything as fast as the Blackbird–Mach 2.4 will probably be adequate.
But here is really the crux of the issue.
The claim is that with enough leading edge sharpness and the proper contouring behind, you can fly supersonically without shockwaves, except circulation (flow around the airfoil) which produces lift elimates the shockless effect. Why would this be? Well, without lift on a sharp symmetric airfoil the stagnation point would the the leading edge. If you add circulation, perhaps you move the stagnation point so that it is no longer on the leading edge. Could this be the problem? The flow splits at the stagnation point (that’s where it stops), and if it isn’t sharp where it splits, you get a shockwave? If that is the case, well, we’re screwed. No amount of adding in balancing circulation downstream will matter, and adding it to the flow over the wing to cancel it out will mean an end to the lift from the wing. Now you could make an unsymmetrical airfoil such that at the cruise condition the stagnation point is on the sharp point of the airfoil, but you’d have shockwave drag getting to that point (or if you had to fly off design point.)
The proposal is not to build a symmetric airfoil. Stagnation points really aren’t relevant.
Imagine a Busemann biplane, which is really a DeLaval nozzle inside two wings. The top of the upper wing is flat, as is the bottom of the lower wing. That allows the airflow to move past without shock. The ramping occurs within the two wings. Now, Busemann showed that this will have a shock-free flow, but because of the symmetry, it has no lift. Now imagine that the lower wing is dynamic–it’s actually a supersonic airflow coming from a non-shocking duct, with a flat lower surface. The lower surface of the “biplane” (after a short ramp) is a stream of higher-energy air (to satisfy Crocco), that mixes the total flow to provide the anti-circulation to balance the wing circulation.
The idea is to provide that balance to eliminate the need for the highly entropic downstream vortices, that require far more energy than that required to simply provide that balance. It spreads the residual shocks over a much larger footprint, reducing almost to insignificance the PSF on the ground, and essentially eliminates the wave drag.
Bottom line: if this works (and I don’t claim that it will–only that it’s not obvious to me that it won’t), this means wide-body supersonic aircraft, at non-ozone-eating altitudes, at ticket prices comparable to subsonic ones. It means obsolescing the current subsonic fleet in the same way that prop-driven airplanes were put out of business by jets, other than niches.
I think that it’s worth spending a tiny fraction (how about a percent of one year’s budget?) of the billion-plus dollars that NASA wasted on the High-Speed Research program, but NASA didn’t agree in the late nineties, even when Congress specifically appropriated it.
I was listening to Fox just now, and they ran a report on summer camp for Palestinian children, at which instead of making lanyards and leather products, learning to swim or sail, and engaging in various sports, they are learning to sneak past Israeli checkpoints, and the virtues of dying for the Palestinian cause. You know, the kind of child abuse that Charles Johnson documents on a regular basis.
And then I recalled that people like Human Rights Watch have actually expressed concern about the use of children as soldiers. Surely, thought I, they will have had something to say about this?
I wandered over to see, and sure enough, it’s a major area of concern. So I clicked on the link on the right of the page, for specific area reports, confident that I’d find the abuse described above reported in detail, with appropriate opprobrium.
But (and I know you’ll be amazed to hear this), there was no obvious mention of it among the reports as listed. Oh, wait, down toward the bottom, there’s a discussion of Lebanon, which at least is in the neighborhood. We discover there that some civilians have been expelled from Lebanon for refusing to join a militia.
Well, that sounds promising. Of course, am I cynical to suspect that the only reason this gets a mention is because, according to the little blurb, it is “an Israeli auxiliary militia”?
But of course.
But I wanted to be fair, so I decided to dig down another level, to the latest (2003) overall HRW report on the subject.
This showed a little more promise–it has a section called “ISRAEL AND THE OCCUPIED PALESTINIAN TERRITORIES.”
Surely, I thought, now we’ll find out about all of this turning young Arab children into Jew-hating killbots.
Imagine my surprise again, to learn that they discuss:
Now, arguably some of these, if true, can certainly be said to be human rights violations, but I’m straining my brain to determine how they constitute forcing children to be soldiers, which I thought was the point of this particular report. And as to the Palestinian summer camps that Charles and others point out?
There was no evidence that the Palestinian Authority (PA) recruited or used child soldiers. In May 2002, the PA addressed the United Nations Special Session on Children and advocated the application of the CRC-OP-CAC, which prohibits the use in hostilities of those under the age of eighteen.129 In 2002, the PA also reaffirmed its commitment to the Coalition not to use children in hostilities in a private communication…
…During 2002, both Hamas and Islamic Jihad disavowed the use of children after under-18s were involved in suicide bombings and armed attacks on Israeli settlements in the Gaza Strip. A Hamas statement in April 2002 called on mosque imams
I couldn’t quite figure out how to categorize this one. There are stories of children being raised by wolves, but here’s the first case, at least of which I’m aware, of a man being raised by chickens.
It will be certain to be the butt of jokes, but of course it’s a tragic situation. I really mean it–once you get past the absurdity of it, it really was catastrophic for the poor guy.
But it could have been worse–he was fortunate that it happened after he had at least developed the ability to speak. Children raised without human contact from birth never develop the ability to do so–there’s a certain critical point in development and the wiring of the brain during which speech is acquired, and if you miss it, you’ve apparently missed it forever. The story claims that he is learning (or relearning) how to speak, and presumably to eat with utensils instead of pecking.
Of course, as the old joke in the Woody Allen movie (Annie Hall?) went, they may not want to go too far in rehabilitating him. They won’t get any more eggs. Besides, he may have a thrilling career ahead of him as a sports team mascot.
Michael Mealing reminds us about this weekend’s Return to the Moon conference, in Vegas. So I do too…
On next week’s thirty-fifth anniversary of the first manned lunar landing?
[Via Rob Wilson]
[Update a few minutes later]
Boeing has established an anniversary web site.
Via RLV News, the presentations from the most recent COMSTAC meeting are available. I haven’t read any of them yet, but I figured I’d post a pointer. I’m a little snowed under trying to make sure I’ve read everything I ought to read in order to do a decent job for the SOI, but I think the paper by Terry Hardy on Ec[*] calculations is a good place to start. I’m beginning to think that the single best paradigm change for moving towards a sustainable and vigorous spaceflight industry is a public safety regime that doesn’t use Ec as a figure of merit. Ec is a little bit like man rating in that it implicitly assumes that the norm for space vehicles is that they blow up with some regularity.
[*] for those not already familiar with it, Ec is the expected number of casualties from operations of a given launch vehicle. You need less than 30 casualties per million flights in order to get a launch license.
Reader John Breen points out this “Foxtrot” comic strip, about a little kid making an X-Prize attempt.