Thanks for posting this, Adam

I'm not sure how much faith to place in the illustrations appearing in Popular Science, but assuming that they're reasonably faithful, here's my impression:

I'll never entirely dismiss anything that Jim Benson sets his mind to, but on the whole, the design looks like an amalgamations which is overly-wedded to heritige technology. I'm a big fan of using off-the-shelf hardware in the service of a good design. However, using off-the-shelf hardware *instead* of a good design is not a great idea. It'll usually save you a lot more than it costs.

Take the airframe that they're using -- basically recycling the X-43. My understanding is that the X-43 was designed for brief hypersonic cruises up to mach 10. The modifications required to upgrade it to a mach-25 re-entry vehicle would probably be significant. Quite possibly more significant -- and quite certainly less elegant -- than simply starting with a blank piece of paper. I'm sure that Gary could address this issue much more thoroughly than I, however.

Next concern is the stack configuration itself. It is very Space Shuttle-like, and that isn't a good thing. Even with boosters that can be shut down, its still an inherently unsafe configuration with no survivable abort scenarios during many stages of the launch. And even if everything always works correctly (which it won't), it's still a pain in the ass to recover, refurbish, and integrate a stack like that on a regular basis.

I'm not a fundamentalist when it comes to my preferred launchers, but I do believe that a successful commercial RLV will take one of the following forms:

- Recoverable vertical booster w/ a capsule on top, as in what SpaceX is presumably planning with the Falcon V. One thing I *am* fundamental about is the number of engines on such boosters. You should either use 1 engine, or 5+ (for an engine-out capability). Anything else increases both complexity AND risk, and is thus Bad Design. Yes, I consider all EELVs (save for the Delta IV light) to be Bad Design.

- 2-stage VTVL; picture a Delta Clipper atop a macro Delta Clipper. This is the path that both Blue Origin and the lesser-known but really cool Masten Space is pursuing.

- Winged HL airlaunch -- using either a very large existing carrier plane, or some new kind of carrier technology, such as a lifting-body airship or a fanwing. Presumably Scaled is looking at something like this.

- winged VTHL bimese -- like some European project (whose name is escaping me at the moment) -- where you've got two identical airframes launched belly-to-belly, Where one of them is only a booster stage. This is the path that SpaceDev would probably be best at pursuing.