Chair Force Engineer

Thursday, September 22, 2005

Marine Shuttle?

The US Marines are seriously considering the development of a spacecraft that could put Marines anywhere on the globe in the matter of a few hours. It's a 21st-century extension of the Marine concept of rapid mobility and expeditionary forces.

A technical solution will not be simple. A ballistic spacecraft would put severe G-forces on the Marines; it's likely that they would be killed by the extreme deceleration. Further, today's rockets are too tiny to send a significant number of Marines anywhere on the globe. A spacecraft based on the X-37 or Common Aero Vehicle could only fit a few Marines, if it were to work at all.

Then I got a crazy idea, based on the craziest of sources. In the James Bond movie Moonraker, an Air Force shuttle delivers "Space Marines" to attack Drax's space station. During a recent episode of McLaughlin Group, pundit Pat Buchanan (reference my last post on pundits who should avoid comment on space policy) suggested that the shuttle be given to the military. His logic was that the shuttle was too dangerous for civilians, but too valuable a commodity to be retired. The military would be willing to accept the risk (except for the fact that the Air Force never wanted the shuttle, and it was forced down their throats by the Nixon White House, in which Buchanan worked as a speechwriter.)

If the Marines want a rocket to ride to a trouble spot on the opposite side of the earth, why don't they use the shuttle? It's capable of a low-stress, lifting re-entry. Its payload bay could carry a sizable contingent of Marines, despite the shuttle's 50,000 pound bringback capacity. Marines are known for doing extremely dangerous tasks that border between incredibly brave and stupid; perhaps a space shuttle flight would fall into this category. Suborbital military missions were given consideration during the shuttle's design, which necessitated the external tank.

With the space shuttle rumored for an imminent retirement, letting the Marines use it wouldn't be such a bad idea. There's no need for them to reinvent the wheel.

Wednesday, September 21, 2005

When Idiots Try to Comment on Space

Traditionally, I have loved savaging media pundits like Gregg Easterbrook and Elanor Clift when they have offered their half-witted insights into space policy and rocket science. It is generally wise to leave rocket policy to the rocket scientists, lest a layman make a fool of himself. The most successful space policy decisions have been made when the people who actually understood the underlying science were given maximum authority.

In the case of Michael Griffin (NASA's administrator,) this situation is brought to a logical extreme: one of the nation's most brilliant astro engineers is now the most powerful space policy-maker in the country, and perhaps the world. On the other end of the spectrum, we have self-appointed media "experts" like Martin Sieff who seem to think there is a strong parallel between the lunar return program and ballistic missile defense.

Where do I begin when intellectually tearing Mr. Sieff a new oriface? My biggest problem is that he tries to make the case that "rockets aren't as reliable as they used to be." Bull-plop. Didn't he watch that sequence in The Right Stuff where it shows rocket failure after failure during the late 50's and early 60's?

Space launch has generally become more reliable as history has progressed. The engineers had to start somewhere, so the first orbital launches in the 1950's were highly unreliable. Early in the space program, Thor missiles exploded quite often (again, refernce The Right Stuff.) Atlas rockets had a notorious habit of blowing up, too. This made NASA's Mercury-Atlas program even more risky. As time went on, engineers learned from their mistakes, and rockets became more reliable.

Today, the Delta (descendant of Thor) and Atlas rockets have become highly-reliable launchers. The Atlas II and Atlas III rockets (recently retired) combined to make 69 successful flights with no failures. The Delta 7000 series, currently the workhorse behind GPS and Mars missions, has a 97.94% success rate.

In the case of the last two failures of Ground-Based Midcourse Defense (GMD,) it is true that the interceptor missiles never left the ground. However, if Mr. Sieff actually did his homework, he'd see that neither failure had anything to do with the launch vehicle. The test on December 15, 2004 ended when an anomaly caused the launch system to shut down. The test of Feb. 14, 2005 also ended when the ground equipment failed.

Solid rockets are fairly simple and well-understood. As the astronauts say about the shuttle's solid rockets, "Once they ignite, you know you're going somewhere." In the case of GMD, the rockets were never ignited. The rocket is merely a small part of a highly-complex, integrated system that is designed to essentially hit a bullet with another bullet. In spite of GMD's setbacks, the Aegis missile defense system soldiers on, displaying extraordinary results during testing.

What we have is a newsman who will deliberately ignore the facts to prove a contention that is very wrong. While the shuttle was the wrong direction for manned spaceflight, the unmanned side of the space industry has only been getting better. The "back to the future" approach of NASA's moon plan has absolutely nothing to do with missile defense.

Mr. Sieff knows that nobody buys newspapers to read the good news. Papers and news programs only garner audiences when they offer up gloom, doom, and sensationalism. Martin Sieff is trying to apply the song "I Ain't as Good as I Once Was" to American space efforts. It would be wise to leave that song to Toby Keith.

Saturday, September 17, 2005


The curmudgeon of the space pundit community, Jeffrey Bell, has an intriguing screed against Single Stage to Orbit rockets that deserves a look, followed by an intellectual discussion.

It should be noted that only a very small minority of the engineering community believes in single-stage rockets. All competent engineers know that, while the basic governing equations of space flight do not exclude Single-Stage To Orbit (SSTO) reusable rockets, the equations do tell us that SSTO is enormously challenging and downright impractical.

The Delta Clipper (DC-X) has often been dismissed as a stunt by supporters of the conventional "expendible rockets" paradigm. While DC-X clearly did not get us any closer to a single-stage reusable rocket (contrary to the optimism of G. Harry Stein in the recommended Single Stage to Anywhere,) the DC-X was an important program that did make several valuable contributions. It showed that a hydrogen-fueled rocket could be launched from austere facilities by a skeleton crew, hover and land, then get turned around and reflown in a reasonable amount of time. The project was an example of lean management and rapid prototyping.

If Delta Clipper had been fully funded, perhaps it could have resulted in a reusable SSTO. The concept was to build and test (now given the buzzword nickname of "spiral development,") incrimentally achieving the full performance after a series of increasingly-capable prototypes. In the mid-90's Mitchell Burnside Clapp (at the time, a Captain at Kirtland) proposed building a Mach-3 capable "DC-XB" and an enlarged "DC-XC."

In short, while Jeff Bell's physics and his mass figures for DC-X are indisputable, it's not clear that DC-X was the pinnacle of SSTO technology. In actuality, DC-X was probably on the heavy side, compared to what McDonnell Douglas could have built with cutting-edge materials and structures. DC-X was designed for a simple mission: take off, hover, and land. A high fuel fraction isn't needed for that.

Assuming that we could have incrimentally built ourselves up to SSTO (perhaps by the time "DC-XZ" came along,) the useful payload would have been such a small fraction of the total launch mass that we'd have to ask if all the effort was worth it. An SSTO will always have to carry the mass of empty tankage to orbit. A Two-Stage To Orbit (TSTO) allows you to drop off some of the dead weight, recover it for reuse, and put more payload in orbit. The more stages you have, the more payload in orbit for a given liftoff weight. However, the addition of each stage creates more complexity, and each staging event carries a significant risk of ending the mission.

After taking a long look at the old concepts for reusable launch vehicles, I have to favor something akin to Max Faget's "DC-3" space shuttle concept. The two-stage rocket (fully reusable, unlike the space shuttle that emerged) consisted of a booster and orbiter that both resembled airplanes. The booster would burn out, then return to base with its onboard jet engines. The upper stage (orbiter) would only ignite after the booster burned out, and it would fly to orbit without dropping propellant tanks or solid rocket boosters.

The critical flaw in Faget's DC-3 was that the orbiter dropped like a brick during re-entry, from the entry interface all the way until it reached subsonic speeds. This was a great technique for reducing vehicle heating (which is why SpaceShipOne uses a variation of this re-entry mode,) but it introduces a tendency to spin at hypersonic speeds.

Faget's orbiter had some novel features, like a straight, high aspect-ratio wing for good subsonic flight characteristics, and jet engines to enable ferry flights and aborted landings. However, it would be a shrinking NASA budget (and a demand from the Nixon White House that NASA's shuttle conform to the Air Force's proposed Vandenberg mission requirements) that doomed fully-reusable shuttles like Max Faget's DC-3. We got stuck with the space jalopy we have now, and the safety of the astronauts was the tradeoff.

If Burt Rutan or other rocket visionaries want to build a reusable orbital rocket, they would be wise to look at the work performed during the late 60's, before the shuttle's development budget was cut. They would also be wise to build a mini-shuttle (akin to the X-20) that would take many of the unknowns out of development.

The space shuttle's biggest failing is that it tested too many new technologies despite being an "operational" system (opposed to being a prototype system.) No vehicle had ever flown with the shuttle's fragile heat shield or reusable hydrogen engines before. As a result, NASA had no clue how difficult it would be to maintain the orbiters between flights until it had actually flown them a few times.

With hindsight being 20/20, we should have a good idea of how to competently build a reusable rocket. The question is, who will build it, what will its mission be, and where will they find the startup funds?

Saturday, September 10, 2005

Falcon Fallout

Late in July, I created a stir by speaking at length about the Falcon IX rocket. Suddenly, my little blog came to the attention of all space boosters wanting to get the inside story on Elon Musk's next rocket.

However, the newfound fame (infamy is a better term) made me realize that it was inappropriate for me to comment on Falcon IX before a public announcement had been made. This was wrong on my part, a youthful indiscretion, and I hope to make sure it never happens again.

My biggest fear is that Elon Musk would be pissed at the Air Force because of something I had said. However, it appears that Elon Musk has much bigger reasons to be pissed off at the Air Force. All we can hope is that this dispute is resolved, that the Falcon I inaugural launch (scheduled for October) goes off without a hitch, and that SpaceX and the Air Force can build a strong and mutually-beneficial relationship.

God Damn Right, It's a Beautiful Day

The road trip to Clovis to see the Cannon AFB Air Expo went well. I've never driven on the interstate for seven hours in a single day before, but having friends and music helped the time fly by.

Plenty of interesting things happened during the drive. I played chicken with a semi and lived to tell the tale. On the way back home, I was tailed by two Dodge Vipers that were on display at Cannon. Later in the drive, I was passed by a truck and trailer that were carrying a third Viper, one which actually raced at Cannon. I also got caught in a charlie-foxtrot of trucks that kept passing me up, only for me to pass them when they slowed down. I eventually overcame.

Fuel economy was good. At one point on the way down I was getting 40 miles per gallon. Start and stop driving on base reduced this to about 36 mpg for the first leg of the trip, and the return leg probably saw similar gas mileage.

The drive to Cannon from Albuquerque isn't too scenic. Aside from the mountains east of Albuquerque, it's all open prairie, with the occasional grain silo or herd of cows. 84 runs parallel to some train tracks, and we did see a really long freight train. There were a few small and scenic towns, but that was the only trace of civilization.

The most rewarding part of the trip was getting to be with other bachelor lieutenants and learning to toss our pre-conceived judgements out the window. It was a great group of guys, and I'd love to take the trip again.

(Title of this post taken from the Road Trip sountrack)

Tuesday, September 06, 2005

Still standing after three shots

I finished my Air Force-mandated immunizations this afternoon. For some reason, I remember it as being much more painful back in my youth. I was more of a wuss then, but I also think that the hospital supply companies have put more effort into taking the discomfort out of vaccination. When it was all done, I got to wear not one, but TWO Snoopy band-aids on my upper arm. Score!

Thursday, September 01, 2005


When I worked for the university, I discovered that getting money from an engineering professor (to buy a gift for our secretary) was like getting blood from a stone. Still, there were a few professors who were quite generous.

After leaving academia for the world of practicing engineers, I can say that the same fiscal behavior holds true. I bought breakfast and lunch for the engineers during today's meeting, and asked for three dollars from everybody to cover my losses. At the end of lunch, several engineers hadn't paid up. It was left to the people who already had paid to make up the difference. I'm grateful for the people who showed extra generousity in making sure that I broke even.

Watch out, Radioactive Man!

The Nuclear Surety Inspection at Kirtland went well, according to the base paper. I was able to experience part of the inspection with the Readiness Support Team, which decontaminates people emerging from an accident site.

The team performed well, given that it was the first experience running a decontamination station for many of us. Mad props go to the captain, who led us ably during his first drill.

All I could think of during the inspection was how tight the mask was against my face. I kept adjusting it, relieving pressure on my forehead. Note to self: loosen the mask next time. The hood will keep it plenty tight.

Being on the RST is a pretty visible volunteer opportunity, and I'd recommend it to anybody who gets the chance. We get in the base paper all the time, and we get called away from work to run around in yellow suits and duct tape.