I haven't read the whole thing yet, but here's a long piece from ABC News about the prospects for public space travel, and it seems to take it quite seriously.

Amazing! He is only slightly clueless (he bemoans Big Government Programs while admiting that the best stuff will come from the private sector) and doesn't understand the rocket equation, but overall, not bad.

The last paragraph is powerful:

Why? Because real, cutting-edge innovations in commercial aviation are at a standstill. Supersonic and hypersonic transports are far too expensive for any responsible company to develop alone, and Congress is essentially clueless as to the immense benefits of nationally and fully financing such major projects for the greater good. So the pathway not only to orbit, but to major innovations in transportation between points on the planet will come from brilliant private, entrepreneurial collaborations in space. In truth, the race to achieve routine passenger spaceflight is also the cutting edge of aviation's future.

His book looks like it may be worth something, too.

Supersonic and hypersonic transports are far too expensive for any responsible company to develop alone

This should be a clue that they're probably not worth developing at all. A technology where taking the next step is too expensive is probably not going to be able to survive in the technological jungle, and will have a very hard time progressing further even if it does find a niche.

"Supersonic and hypersonic transports are far too expensive for any responsible company to develop alone

This should be a clue that they're probably not worth developing at all."

It may well be that supersonic and hypersonic air transports aren't worth developing, but I've never understood the notion, implicit in your comment, that high development costs automatically mean a technology is not worth having. History is full of technologies that were difficult (and hence expensive) to develop, and yet have proven both useful and economically viable once mastered. I question whether any single company could have borne the full development cost of jet engines, computers, or the internet (to name just a few), yet all of these seem in retrospect to have been "worth developing."

High development cost certainly creates a barrier to entry, but it does not necessarily mean the resulting technology, once fielded, will be uneconomic. Or, to pick up on your metaphor, survival in the jungle depends more on the characteristics of the mature beast than on how difficult the gestation was. Or so it seems to me.

I've never understood the notion, implicit in your comment, that high development costs automatically mean a technology is not worth having.

It's not entirely automatic, but it's a strong indicator. Successful technologies become successful by exploration of design space on multiple paths, and the more the better. This becomes more difficult as the cost of a step increases. It's an illusion that designers are smart, unbiased and unencumbered enough to be able to pick the best approach beforehand.

Being too expensive for more than a few development efforts (or even just one) also means the market is limited (relative to the development cost). Offshore oil platforms were expensive to develop, but the market for them was also sufficiently large, so many different designs were tried over the decades.

If there really was a large, robust market for supersonic passenger aircraft, then there would be a strong incentive for private companies to develop them, and you'd see multiple efforts to do just that. So why don't we? For most air travelers, the time saved traveling above the speed of sound would not be worth enough to justify much increase in the ticket price. The market has optimized on cost-reduced high subsonic aircraft.

The market has optimized on cost-reduced high subsonic aircraft.

Not to mention vastly improved levels of service and comfort for high value travellers.

I recently got upgraded to Cathy Pacific First on a leg from Hong Kong to London. I had a 6'6", 3' wide flat bed, large desk, power, noise cancelling headphones (which I do have anyway) and an internet connection for email (on SAS and Lufthansa Skype works fine too).

One of the considerations was having the high value exec arrive unable to work, or be out of the loop for 12 hours. Neither applies now. You can arrive pretty much ready to go, and you've been able to work, talk and function in the plane.

It is going to make sitting in Economy all that much harder :)

Successful technologies become successful by exploration of design space on multiple paths, and the more the better. ... It's an illusion that designers are smart, unbiased and unencumbered enough to be able to pick the best approach beforehand.

This actually supports my point: It's not clear that the "goodness" of an engineering solution (or a basic technology) is in any way related to the difficulty (and hence cost) of finding it. As you point out, all that "exploration of design space" costs money... but that doesn't necessarily mean the products and technologies it leads to will be expensive to produce and use.

Insisting that the private sector bear all development costs within a purely commercial model risks depriving us of wildly useful (and profitable) technologies that have high development barriers to entry. Decoupling development cost through some form of public-sector support, OTOH, mitigates that risks.

I can't prove it, but I'm convinced that's what happened with jet engines: Absent government support in the form of both direct research and military development, I'm convinced the commercial aviation industry would never have developed jet propulsion, because the technological barriers were high and air travel was already so much faster than competing forms of transportation. Many of the same arguments now being used in the supersonic vs. subsonic debate would have been used in the jet vs. piston debate (if any), if developing jet engines had been left solely to the private sector.

Just MHO, of course....

I'm convinced the commercial aviation industry would never have developed jet propulsion, because the technological barriers were high and air travel was already so much faster than competing forms of transportation.

This glosses over other major benefits of jet propulsion. Jet engines are much more reliable than piston engines and require less maintenance. They also have higher power/mass. This is why you see turbine engines instead of piston engines in turboprop aircraft and helicopters.

I don't know if these benefits would have been enough to get to jet propulsion in the absence of a military market. Perhaps development would have been via industrial gas turbines, which one could argue would have been developed for peaking power.

Interesting discussion!

This glosses over other major benefits of jet propulsion. Jet engines are much more reliable than piston engines and require less maintenance.

All true... certainly true now. I'm not sure these things were as true in the years immediately before and after WWII, when piston aeropropulsion was a fairly robust, mature technology and turbine engines were still essentially experimental. More to my point, I'm not sure these once-and-future advantages would have been obvious enough to justify extensive private development spending. The question for the commercial aircraft companies and their risk-sharing customers would not have been "is this technology better," but rather "will this technology make our product enough better than it already is, soon enough, to create a monetary return that can offset $X millions of upfront spending?"

Given how superior air travel already was compared to competing transportation, it's not at all clear to me what their answer would have been. Basically, I think we're close to agreement:

I don't know if these benefits would have been enough to get to jet propulsion in the absence of a military market.

OTOH...

Perhaps development would have been via industrial gas turbines, which one could argue would have been developed for peaking power.

If gas turbine engines had been developed first for industrial applications -- esp. for stationary powerplants -- then I'm even more sure they wouldn't have ended up on commercial airplanes: Aero engines make good generators -- most gas turbine powerplants in service are aeroderivatives -- but it doesn't follow that you can go the other way. A gas turbine designed from a clean sheet of paper for powerplant use would be optimized for efficiency and power output in uninterrupted steady-state operation; it would not be optimized for low weight, efficiency over a wide range of power settings, stable startup and shutdown sequences, thrust transients, or any of a variety of other parameters that are critical to aircraft propulsion but meaningless to ground-based power generation. Turbine engines developed for power stations would have been like computers developed for banks and think-tanks were: Big Iron.

But regardless of whether you buy the jet engine example, I stand by my original point: The difficulty/cost of developing a given technology is not necessarily dispositive of the "goodness" of that technology once developed.