All posts by Rand Simberg

Space Prize Hearings

SpaceRef has a summary of the hearing on prizes for space achievements, held on the Hill this morning.

Molly Macauley made an excellent point:

“Even if an offered prize is never awarded because competitors fail all attempts to win, the outcome can shed light on the state of the technology maturation. In particular, an unawarded prize can signal that even the best technological efforts aren’t quite ripe at the proffered level of monetary reward. Such a result is important information for government when pursuing new technology subject to a limited budget,” she said.

The DARPA Challenge is a good example of that, in my opinion.

Of course, we have the usual caviling:

“While establishment of a NASA prize program is certainly worth considering, we should not be lulled into thinking that it is any substitute for providing adequate funding for NASA’s R&D programs,” cautioned Subcommittee Ranking Minority Member Nick Lampson (D-TX).

Rep. Lampson is one of the representatives from JSC.

Overall, while there were some appropriate cautionary notes, there seemed to be a consensus that this was a good idea. Let’s hope that they can get the funding now.

More Post-Intelligencer Thoughts

Andrew, that piece really is worse than you say.

The trouble is that the space program’s purposes are inseparable from its Cold War-era context.

No, the trouble is not that they are inseparable–it’s that we’ve never made a serious policy attempt to achieve such a separation.

He gets the NASA budget wrong (it’s closer to twenty billion than fifteen). That doesn’t change his point (in fact it strengthens it, to the degree that it’s valid), but it’s sloppy. It’s also not clear that the plan will require a significant increase. That was one of the selling points of it–that by putting down the Shuttle program, we can shift funds to the new activities.

Along the way, the space commission he appointed has offered up a smorgasbord of absurd side benefits, such as possible improvements in our (so far non-existent) ability to deflect threatening incoming asteroids, of the sort that may have severely disrupted life on Earth as recently as 35 million years ago.

I guess his point is that it doesn’t happen very often, so it’s not a benefit. He’s probably unaware that if the Tonguska event had occurred on the eastern seaboard of the US, instead of in Siberia, we could have lost millions of lives only a century ago.

It really is a typical “why pour all that money into space when we have so many problems on earth?” rant. Nothing new here.

[Update in the afternoon]

Jeez, I’m almost starting to feel sorry for the schmuck. Dwayne Day really goes after a gnat with a howitzer in the comments section.

I’d say that he’s been pretty thoroughly discredited. Unfortunately, most of the PI’s readers probably don’t read this blog.

Why Not NOAA?

Can someone explain to me why Aura is a NASA mission, and not a NOAA mission? It seems to me that if one wants to focus NASA better, this is the kind of thing that would be better done by a different agency.

Myopic

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.

New Thinking?

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.

More Supersonics

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.