Chair Force Engineer

Tuesday, January 31, 2006

Roadkill Rabbit

I was disturbed last night when a bunny ran in front of my car. While I slowed down to avoid hitting it, the bunny inevitably scraped the underside of my car and met his unfortunate death. I guess that these incidents are inevitable around Kirtland, where Jackrabbits and Prairie Dogs run amock. But that still doesn't make me feel good about it.

The irony of it all is that just hours earlier, I had been joking with my superiors about "car hunting," or deliberately using one's vehicle to kill animals for food. I guess it's not so funny anymore.

Monday, January 30, 2006

Delta Death--Delayed?

Some reports on the Internet speculate that Boeing will kill off the Delta IV after the "United Launch Allaince" merger is finalized. Supposedly Boeing will base its decision on military needs. My educated guess is that the death of Delta IV will not be coming for a while.

My biggest strike against Delta IV is that it has launched fewer times than its rival, the Atlas V; and when it does launch, those missions face repeated delays due to faults of the launcher. However, Delta IV has one advantage over Atlas V: a heavy-lift version that can put 25 tons in low earth orbit.

Presumably, United Launch Alliance could build an Atlas V Heavy to make up for the loss of Delta IV. Yet this is easier said than done. The Delta IV Heavy demo mission in December 2004 showed us how difficult this can be--cavitation in the propellant lines led to premature shutdown of the first stage engines, and the demo payload was left in a highly-eliptical orbit. Since then, Boeing has investigated the anomaly and has a fix that should hopefully work in the future.

At this point, it isn't wise to reinvent the wheel by coming up with an Atlas V Heavy (as long as Delta IV Heavy works on future missions.) United Launch Alliance may decide to fly the Atlas V for most missions and to whip out the Delta IV Heavy only for the missions where a heavy lifter is needed. In that sense, it will become a "pad queen" just like the Titan IV it's replacing--a rare, maintenance-intensive rocket that flies a handful of high-profile missions in its lifetime.

[EDIT 1/31/2006] Many of the other bloggers who are linking to this article are of the belief that the EELV program is a fiasco. I wanted to make it clear that I do not share this opinion.

While competition was planned from the outset, the collapse of the commercial satellite market has made real competition a fantasy. The value of two separate launch systems comes from redundancy. If a problem grounds one fleet of rockets, there will still be a second rocket fleet to launch essential payloads. As long as that redundancy is available, EELV will not be a failure, IMHO.

Saturday, January 28, 2006

Slipping the Surly Bonds of Earth

The traumatic loss of Challenger, twenty years ago today, is just as tragic today because we have largely ignored the accident's lessons. Three years ago from this Wednesday, Columbia was lost in a very different accident, but one which can be traced to similar management practices.

History has not done a good job of capturing the atmosphere that existed at the time of the Challenger disaster. For NASA, the year 1985 had been a productive one (by today's standards,) but the nine shuttle missions from that year fell far short of the predictions for 50 missions per year when the shuttle program was first authorized.

For 1986, NASA was attempting a launch schedule with even more flights, including the first launch from Vandenberg into polar orbit, two planetary probes (Galilleo & Magellan,) the Centaur liquid-fueled upper stage (which was supposed to launch the afforementioned probes,) and the Hubble Space Telescope. Challenger's final flight was a mission which had been originally manifested for fiscal year 1985 but had faced repeated delays. If NASA couldn't launch a "routine" satellite-deployment mission with a teacher on board, how could it launch the more risky missions later in the year? Obviously, the pressure was mounting to proceed with the launch, despite concerns that the shuttle was being operated in dangerous temperature conditions. The crew of the previous mission, STS-61C, had seen the mistakes people made while under schedule pressure; their mission was almost launched in spite of a partially-vented external tank.

Besides the oft-cited management problems, there were a tremendous number of technical mistakes that doomed the basic shuttle design.
--The selection of parallel staging (two SRB's burning at the same time, flanking the external tank) instead of serial staging.
--The selection of Thiokol's four-segment SRB's over Aerojet's single-segment SRB's.
--The selection of solid rocket boosters over liquid rocket boosters, despite the warnings of Wernher von Braun.
--The lateral mounting of the orbiter, which would preclude any chance of escape even if an escape system were available.

The entire shuttle design was driven by an ill-conceived attempt to marry the requirements of NASA (moderate sized payloads to easterly orbits) with those of the Air Force (large payloads to polar orbit, with sufficient cross range to return to base.) Many within the Air Force never wanted the shuttle, because manned spacecraft drew unnecessary attention to classified missions (and the Air Force baseline mission was cancelled after Challenger anyway.) To boot, NASA was trying to attempt something that had never been attempted before: the development, test and operation of a manned, winged, reusable spacecraft. Had NASA and the Air Force proceeded with a smaller experimental vehicle (like the X-20 DynaSoar,) the limitations on the shuttle's flight rate and other problems could have been revealed before the shuttle program was conceived.

I was too young to understand Challenger or even remember it when the accident took place. But the disaster was so great that the idea of totally ending manned spaceflight gained traction in mainsteam America. Overseas, the rest of the world no longer was awed by America's technological might or ingenuity.

On the evening of the disaster, President Reagan postponed his State of the Union address and delivered a speech, penned by Peggy Noonan, eulogizing Challenger's lost crew. Reagan (and Noonan) closed the speech by citing lines from High Flight, by John Gillespie Magee. The poem has become a staple of the Air Force ROTC education (which, I assume, took place as a result of the speech.)

The last three lines of the poem sum up so succinctly the feelings and motivations of the fallen astronauts, and indeed all the fallen aviators.

And, while with silent lifting mind I’ve trod
The high untrespassed sanctity of space,
Put out my hand, and touched the face of God.

For those on the ground, we should best heed the last line of President Bush's address to the nation when Columbia was lost: ...but we can pray that all are safely home. Pray we will, but we must also use our God-given abilities to bring the astronauts who rely on us safely home.

Thursday, January 26, 2006

Mars or bust

NASASpaceFlight.Com is reporting that NASA is conflicted about propulsion systems for a post-2030 mission to put humans on Mars. Both choices would use a nuclear reactor. The first method would employ a nuclear-thermal rocket, which would force vaporized hydrogen through a nozzle. The second, nuclear-ion rockets, would use the reactor's electricity to propel charged Xenon gas from a set of thrusters.

The tradeoff between the two systems is huge. Nuclear-thermal rockets have moderate efficiency (Isp between 800 and 900 seconds) and moderate thrust (tens of thousands of pounds.) Ion rockets have extremely high efficiency (Isp ~5000 seconds) but very weak thrust (only fractions of a pound.)

There is also a third way which has been woefully underfunded over the years--VASIMR. It would use large nuclear reactors (producing megawatts to electricity) to power microwave generators. The microwaves would excite a hydrogen plasma that would be ejected from the rocket by magnets. VASIMR offers similar Isp to ion rockets with sufficiently more thrust. Still, there is a long way to go until VASIMR is ready, and a lot more money will need to be invested in the technique.

The idea was pioneered by astronaut Franklin Chang-Diaz (one of the most experienced US astronauts, with 7 shuttle missions to his credit.) NASA has now decided to commercialize the concept with Chang-Diaz's company, Ad Astra Rocket Co. Perhaps some forward-thinking company will subsidize Ad Astra's continued research into VASIMR, with hopes it will be ready for primetime by the year 2030.

If we must choose between nuclear-thermal and nuclear-ion, I hope that a combination of both is selected. While a pure-ion rocket can get away with less propellant mass than a nuclear-thermal one, the mission time is made much longer due to the low-thrust spiral out of earth orbit and the low-thrust spiral to brake into Mars orbit. Humans will probably be cooked alive during a slow transit through the Van Allen Radition Belt. I would propose a reusable, nuclear-thermal tug to at least accelerate the crewed spacecraft to an orbit higher than the radiation belt, before the ion rockets are activated.

Besides the propulsion system debate, NASA has interestingly endorsed artificial gravity. This addition presents some challenging tradeoffs. It's known that prolonged exposure to weightlessness wreaks havoc on the human body, but the extent of the damage is not known (because the longest continuous stay in space for a human is 439 days, about half the length of a Mars mission.) Artificial gravity fights the ill-effects, with the drawback of dictating a larger and heavier spacecraft (to create the centripetal "artificial gravity" without the Coriolis force which leaves humans dizzy and disoriented.)

At the same time, an artificial-g spacecraft would require plenty of testing in earth orbit before it was ready for a Mars mission. Perhaps artificial-g will create more problems than it solves. Much like the exploration of Mars, if we never go, we'll never know.

Tuesday, January 24, 2006

Rocket-Powered Rosebud

As jet aircraft made their way onto aircraft carriers, it was soon realized that aircraft carriers would need to grow to support the increasing takeoff lengths for these planes. A solution to longer decks was invented by the British in 1950: the steam catapult.

The Royal Navy quickly adopted the steam catapult, and the US Navy followed suit. Now carrier-based planes could be shot to takeoff speeds on existing decks. However, some people think that similar catapults (electromagnetic catapults or rocket-sleds) can help push rockets into space. While there is some historical precedent for this, you can count me as a skeptic.

Eugen Sanger, the Austrian who designed rocket planes for the Nazis in World War II, originally viewed the rocket sled as a means of takeoff for his "Sanger-Bredt Antipodal Bomber," also known as "Silverbird." After the war, Sanger continued his studies while working for Messerchmidt-Bolkow-Blohm. The Silverbird (which was supposed to skip across the upper atmosphere like a stone skipping across water, except for the heating problems which Sanger apparently didn't know about) evolved into the RT-8-01. This was a two-stage rocket, both stages with delta wings. While the RT-8-01 also used the rocket sled, Sanger's team had settled on vertical takeoff for its final iteration, the Sanger I.

Similarly, the American engineer Phillip Bono wanted to build a rocket sled to launch his Hyperion single-stage spacecraft. However, Bono realized that to take advantage of the speed boost, the rocket sled would have to run vertically with respect to the launch site. He proposed building his rocket sled up the side of a 1.7 km mountain.

One important thing to remember about catapults and rocket sleds is that they accelerate their associated spacecraft at low altitudes. The denser atmosphere near sea level (or even within a few miles of sea level) makes a huge difference in the drag and heating that the spacecraft will undergo.

As an example of the challenges of high-speed, low-level flight, we have the F-111. While "The Vark" was an exceptional plane for flying supersonically at low altitudes, this ability came at the expense of structural weight. As the F-111 was the product of a misguided "joint" effort between the Air Force and Navy, the two services had competing requirements for the F-111. The Air Force wanted it to fly supersonically at low altitudes so it could penetrate under the radar coverage of Soviet anti-aircraft missiles. The Navy was willing to settle for a high subsonic speed at low altitudes, knowing that a lighter structure was needed. The resulting F-111 could break Mach 1 at low altitude, but it was too heavy for safe carrier operations.

Even today, while planes like the the F-14, F-15, and F-16 can break Mach 2 at high altitudes, they can't achieve this same speed at low altitudes. The original B-1A bomber, with movable intake ramps, could make a Mach 2 dash at high altitudes only; the revised B-1B, with fixed inlet ramps, is optimized for flight just over Mach 1 at low altitudes.

Even if a lightweight airframe could withstand the stresses and heating associated with Mach 3+ flight at altitudes of just a few miles above sea level, there is still the problem of controlling the rocket's trajectory. Much like running the Hyperion up the side of a mountain, a sled-launched rocket must transition into a near-vertical trajectory. Not only does this maneuver bleed off precious velocity, but the aerodynamic stresses it imposes dictate a stronger structure lest the vehicle break apart.

While the book isn't entirely closed on rocket-sleds and electromagnetic catapults, there are many reasons for skepticism. There are good reasons why rockets have been launched vertically from the ground (and, less frequently, dropped from the bellies of aircraft.) These methods minimize drag and gravity losses without imposing excessive heating or aerodynamic forces.

Sunday, January 22, 2006

Engine Competition

The 2007 DoD budget request will supposedly drop funding for the F136 jet engine, which was supposed to be a competitor to the F135 engine that will power the F-35 Joint Strike Fighter. If history is any indication, the availability of alternate engines would have been a blessing for the JSF.

General Electric (who would have produced the F136) also makes the F110, which validated the soundness of having an alternate jet engine for supersonic fighters. Specifically, the F110 replaced the disappointing engines that had previously powered the F-14 Tomcat & F-16 Fighting Falcon. Derivates of the F110 (known as F118) also went on to power the B-2 Stealth Bomber and U-2S spy plane.

When the Tomcat was first built in 1972, it was powered by the Pratt & Whitney TF30. While this engine was the first turbofan designed for supersonic aircraft, it had many faults, especially the all-too-frequent compressor stall. The engine had already proven to be a disappointment in the F-111 and A-7, but it was the only engine that met the Tomcat's requirements at the time. Likewise, the F-15 Eagle and F-16 Fighting Falcon were designed around the Pratt & Whitney F100, another large turbofan with reliability problems.

In the late 70's, General Electric came up with a Derivative Fighter Engine (DFE) variant of the F101 it had created for the B-1A. With the B-1A cancelled by President Carter, GE needed to find a new market for the engine. the F101-DFE was successfully tested in an F-16 and an F-14.

The results of these trials were so impressive that future F-14's and F-16's were built with the DFE, put into production as the F110. The GE-powered Tomcats and Falcons had better reliability and more thrust. For the Tomcat, the airframe's full potential was finally reached, and the Tomcat could accelerate in a vertical climb. The F-16's powered by the F110 can break the sound barrier without the gas-guzzing afterburner. In short, the healthy competition between Pratt & Whitney and GE resulted in better engines for two fighters.

Surprisingly, the Air Force did not choose to incorporate the F110 into the F-15 Eagle. The logic behind this choice is because the F-15 had an established logistics system and billions of dollars invested into the old F100 (although a similar investment had been made into the F100 engine for the F-16.) However, South Korea announced within the past year that it will be buying F-15K Strike Eagles equipped with the F110, further cementing the reputation of the GE engine.

It's been speculated that if GE loses the F136 contract, it will be put out of the fighter engine business. For GE, the only hopes of future fighter engine sales will be F110's for future F-16's (although the future market for F-16 sales looks bleak,) and more F414's for the Navy's Super Hornet. While the F110 has also been mentioned for the proposed FB-22 "Strike Raptor," the FB-22's chances for production are bleak at best.

In the absence of competition from GE, Pratt & Whitney will likely become fat and complacent (even as it loses market share in the airliner engine segment t0 GE and Rolls Royce.) Most importantly, sole-sourcing the engine buy means that the entire JSF fleet can be crippled by an engine defect.

Thursday, January 19, 2006

Flying Reactors

Score: Science 1, Hippies 0

The successful launch of the New Horizons Pluto probe warrants a hearty congrats to Lockheed Martin, Johns Hopkins, NASA, and everybody else who made the mission happen. The probe will be our first chance to learn in-depth about our enigmatic ninth planet and the outlying Kuiper belt.

Of course, there were plenty of dirty hippies on hand to protest the 24 pounds of Plutonium that will power the Radioisotope Thermoelectric Generators of New Horizons. The press has mentioned that the number of protestors is greatly reduced versus the number on hand for the launch of Cassini in 1997. Still, it's too early to say if this is a sign that nuclear power is gaining more acceptance in the general public.

For an excellent treatise on the topic, I recommend Flying Reactors by LtCol James Downey, Wing Cdr Anthony Forestier, and LtCol David Miller. It examines the political and public policy challenges facing the use of nuclear power for space applications. I was fortunate enough to snag a copy while I was at Maxwell AFB; it's readily available from Air University Press.

Over the next hundred years, we will have to harness the power of the atom if we wish to do anything worthwhile or exciting in space. Engineers must always strive to reduce the risk of an accident, and to minimize the danger in the event of one. And the public must always believe that the science returns enabled by space nuclear power outweigh the risks involved.

Parking Vultures

During today's excursion to UNM, I parked in one of the 24-hour lots off Yale street just south of campus. Basically, you park your car in a numbered spot, then you are on your honor to put your money into a big box with a slot for each parking spot. How well is the lot monitored? I can't say for sure.

As I was walking back to the lot after class, a guy in a beat-up pickup asked if I was parked in one of the lots. While I told him "yes," I kept on walking while thinking to myself, Stay the hell away from me, you creepy bum.

As it turns out, he followed me into the parking lot and asked where I was parked. At the same time, a lady in a beat-up hatchback asked me the same question. As I pulled out, the guy in the pickup rolled into my spot. Apparently he wanted to park in my spot and use up the remaining 23 hours of parking I had bought with my $1.50. Maybe somebody should have told him that it's highly unlikely that you'll get towed away if you don't pay, since the lots don't issue passes when you hand over your money.

Wednesday, January 18, 2006

The Stick is Stuck

The rumor mill at NASA Watch and Space Ref reports that development of the Crew Launch Vehicle (a.k.a. "The Stick") has run into some problems. I feel an "I told you so" coming on here, but hear me out.

The problems revolve around modifying the Space Shuttle main engine. Not only does NASA want to air-start it so it can be used on an upper stage, but NASA also wants to make it cheaper so they can be mass-produced and thrown away after each flight.

Here's some news for NASA: we already have a large, hydrogen-burning engine that is cheap and can be thrown away. It's the RS-68, and it's flown many times on the Delta IV. The RS-68 will probably need some modifications for an air-start as well, but the expendability is already built in. While RS-68 has a lower specific impulse than the shuttle engine (due mainly to the ablative cooling, instead of the shuttle's regenerative nozzle cooling,) it offers more thrust.

Of course, NASA's second engine choice is not the RS-68, but the J-2S. While this engine was a good one back in its day, it hasn't been produced in 35 years or so. Further, it's been revealed that the current upper stage design is too heavy to be propelled by two J-2S's working in tandem. NASA's solution to this one: shrink the upper stage, then add a fifth segment to the solid-rocket first stage. Come on, NASA. It's not like this is rocket science here...

At this point, we have to question the wisdom of choosing "The Stick" over a proven launcher like the Delta IV or Atlas V. While NASA has made a fuss about the challenges of "man-rating" these unmanned rockets, this point is specious. After all, "man-rating" never stopped NASA from using the Redstone, Atlas, and Titan II rockets back in the days when NASA was regarded as a competent agency. Man-rated or not, I'd feel safer riding a Delta or Atlas than I would feel riding in the Space Shuttle.

It would be wise to ask the engineers behind the Exploration Systems Architecture Study, Was "The Stick" really better than Delta & Atlas, or did you just do what Scott Horowitz told you to do? The former astronaut is now Director for Space Transportation and Exploration at ATK-Thiokol. If you think the decision to build The Stick was shady, I'd say that your B.S. detector has been well-calibrated.

[EDIT 1/19/2006] A canny reader of Transterrestrial Musings points out that Scott Horowitz has left ATK and became associate administrator for the Exploration Systems Mission Directorate at NASA in Sept. 2005. While I want to avoid making a personal attack against a man who has done great things for this nation, I wanted to point out that "The Stick" is his intellectual baby, and his positions of influence (at both ATK and NASA) undoubtedly helped it to gain acceptance within NASA.

Outside NASA, I don't think "The Stick" has found much acceptance. While Horowitz and NASA tout the solid rocket's simplicity as enhancing the rocket's reliability and safety, many of us don't agree. We remember the prescient words of Wernher von Braun, who warned against using solid rockets in manned spacecraft. And NASA's dirty little secret is that they still haven't addressed the OSHA issue with retrieval of the 5-segment SRB.

Tuesday, January 17, 2006

E Pluribus UNM

I started my class at the University of New Mexico today. The first challenge was finding a place to park. I looked for a shop that was under-staffed and not visited by a lot of shoppers. The local "Family Dollar" fit the bill. However, I've heard that the local businesses like to tow people away in these situations, so I'll probably shell out the entire $1.25 for a parking spot next time. As long as I'm not parking in UNM's poorly-designed parking garage, I'll be alright.

Class was conducted in a conference room (which the instructor admitted wasn't conducive to learning.) It felt a bit weird to be sitting in a 200-level nuclear engineering class. Still, I'm not the oldest student there.

I kept thinking about the imminent "New Horizons" mission to Pluto, which will use Plutonium, and will hopefully give us the best info yet on the ninth planet. The combaination of astronautics and nuclear power is what will drive mankind's quest to colonize space. While my continued education in nuclear engineering may have to wait until the Air Force (one way or another) lets me become a full-time student, my desire to see mankind as a spacefaring species makes the educational travails worth the while.

Monday, January 16, 2006

Walking on broken glass

The city of Albuquerque is notorious for auto theft. Nearly two weeks ago, I learned this lesson first-hand. A thief in the night (I later learned that my car alarm was heard just before 5 AM) tried pulling my windows down. When that failed, he smashed through the rear passenger window and pulled the door handle. This triggered the car's impotent alarm system, which apparently scared the thief away (as it appeared nothing was stolen from my car.)

Last weekend was spent at A-1 Auto Salvage, buying a replacement window from a wrecked car for $55. This past weekend was spent trying to put the new window in place.

Here's a few tips about trying to replace a car side window.
1) Don't turn to a Chilton's guide for help. Chilton books are expensive and they don't help you worth a damn. They make everything seem easy but don't tell you that you will need specialized tools for half the things you will need to do.
2) When you try to remove the inner door panel (and the window crank on cars without power windows,) you will almost certainly need a special prying tool. They're available at Auto Zone for about $6. (The poor kid at Auto Zone was getting bitched out by his boss at the same time he was helping me. The schmuck running the local Auto Zone has no fricking clue about leadership.)
3) For an amateur, it's almost impossible to put the new window back into the rubber window channel without breaking either the channel, the window glass, or both. They make special tools for doing that, too.

Basically, I tried putting the glass in on Sunday, but quit because the new glass didn't want to go in, and because the Bears game was on (don't get me started on how pathetic their defense looked.) I taped a plastic bag over the window for the evening (a bad choice, when considering the risk of the thief coming back for my car) and took it to a local glass repair shop on Monday. The guy charged me a $25 pittance to put the new glass in, clear the remaining shards of glass out, and reshape my mangled rubber window channel.

The repair looks pretty good, considering that the new window isn't tinted like the other ones (which I can barely notice.) Unfortunately, the new window is somewhat scratched, and it has scum stains from being soaked in my bathtub to remove the junkyard grime. Perhaps I will get the window polished at a later date. Until then, my car doesn't look like somebody punched through the window.

In the near future, I will be making two investments. The first is a better alarm system, which will go off the second somebody touches my car. The second investment is a gun of some sort, so I can shoot car theives in the crotch.

Friday, January 13, 2006

Give me meth, or give me death

Methane, that is.

NASA recently dropped a requirement that the Crew Exploration Vehicle use methane and liquid oxygen for its propulsion system. The space blogs are up in arms about this, and rightly so.

When President Bush proposed his Vision for Space Exploration, he made it clear that the moon was a short-term goal, meant to prepare us for an even greater challenge--putting humans on Mars. The challenge was to show traceability between living on the moon and an eventual Mars mission.

Over the past 15 years, astronautical engineers have come to embrace the idea that, in order to live on Mars, you will need to live off the land. Part of this is making your own fuel by combining carbon dioxide from the Martian atmosphere with hydrogen (brought from earth) to make methane and water. The methane would be used for fuel, while water could be consumed by the crew, or electrolyzed into oxygen for breathing and fuel.

In the initial draft for the CEV's requirements, NASA wanted to use methane for the main propulsion system. The analogue here was obvious: develop methane-fueled rockets now, then apply them on the Mars mission later.

Methane has other benefits, too. Amongst chemical rockets, it's specific impulse is beaten only by hydrogen (and fluorine, but the stuff is too toxic for use in rockets.) It's also considered "space storable," as it doesn't boil away in space as fast as hydrogen does (due to its higher boiling point.) Storability will be important, as the Earth Departure Stage will have to wait in earth orbit until the CEV can successfully launch and dock with it.

NASA's reasons for eliminating methane as a requirement are quite specious, as it will not significantly shorten the development time or budget for the CEV. It's doubtable that an off-the-shelf engine can be used for the CEV. Methane doesn't present any real challenges; existing hydrogen engines like the RL-10 and Russian RD-0120 have been modified to run on methane in tests.

While there's nothing in the CEV's requirements that forbids Lockheed-Martin or Northrop Grumman/Boeing from using methane propulsion, it's unlikely that the big contractors will do anything other than meet the bare minimum requirements. Sadly, America's shattered aerospace industry can't be counted on to deliver a product that is forward-thinking and loaded with growth potential. LockMart and NorthGrum/Boeing have no incentive to pursue methane as a fuel; they have invested billions of dollars in hydrogen and kerosene, while most of the current work on methane-fueled rockets is being done by small companies like XCor.

The big contractors will likely go with hydrazine or one of its derivatives (monomethyl hydrazine or aerozine) as the fuel, and nitrogen tetroxide as the oxidizer. This fuel combination was used for the Apollo spacecraft, and its biggest advantage was the storability of the fuels. It has many major drawbacks, including low Isp and being lethally toxic. Personally, I wouldn't shed a tear if hydrazine was abolished as a rocket fuel.

Much like the Space Shuttle's troubled development, NASA is saving a little bit of money in near-term CEV costs, while losing fistfulls of money and creating more problems in the long run. While methane is not essential to landing on the moon, it will result in a smaller, more capable spacecraft, and it will remove an early hurdle in the human exploration of Mars. NASA Administrator Michael Griffin would be wise to listen to the space bloggers and get the methane requirement put back in the CEV specifications.

Wednesday, January 11, 2006

American Chopper

One of the Army's current high-profile projects is the Joint Heavy Lift (JHL) rotorcraft, which will carry 26 tons of cargo (i.e., the Future Combat System) into the middle of the battlefield. Current designs include a Bell-Boeing quad-tiltrotor (based on the V-22 Osprey,) two helicopters based on Sikorsky's X2 technology (with counter-rotating rotors,) a "variable speed, hingeless tiltrotor" from Frontier Aircraft, and a conventional dual-rotor chopper resembling the CH-47 Chinook on steroids.

What the Army is really doing is foolishly reinventing the wheel. The CH-62 heavy-lift helicopter was Boeing's answer to an Army requirement for a helicopter that could lift 22 tons. The project stalled in 1974 due to drivetrain problems, and Congress withdrew funding. Still, the project made technical headway that led to fly-by-wire helicopters, composite structures on aircraft and the precursors to the V-22's turboshaft engines. The unfinished prototype was airlifted to the Army Aviation Museum at Fort Rucker, Alabama.

The XCH-62 prototype languished at the museum for years, falling victim to neglect. As the 50th anniversary of Fort Rucker neared, the museum was cleaned up for the Army brass who were marking the occasion. Unfortunately, museum director Steve Maxham ordered the XCH-62 to be scrapped in a truly philistine fashion. An important piece of aviation history met an untimely end in October 2005.

It would be unfair to say for certain that a resurrected CH-62 would meet the Army's JHL requirements. One of JHL's goals is to build a faster chopper, as helicopters haven't gotten significantly faster over the past forty years. Still, the CH-62 was a far-sighted program that deserved to be built in its day, and deserved to be preserved as a historical artifact. Wise engineers involved with JHL would be wise to give the CH-62 another look and determine whether it is a good starting point for the new heavy-lift chopper.

Tuesday, January 10, 2006

Back in the USSR

SpaceDev has gone back to the drawing boards, redesigning its "Dream Chaser" space tourism craft for future orbital applications. The move demonstrates a forward-thinking approach and a hopeful look at things to come. It also draws upon a sound design that was examined by the Soviets in the 1970's.

The original Dream Chaser concept used the basic shape of the Orbital Sciences X-34. When I first saw the proposal, I felt that it was the wrong shape for what SpaceDev was trying to accomplish. SpaceDev wanted a rocket that would blast off vertically, fly on a suborbital trajectory, and return its passengers to earth safely. The X-34 was supposed to be dropped horizontally from an aircraft, then ignite its engine and execute a stressful pitch-up maneuver. The X-34 would then fly the same suborbital trajectory and re-entry projected for the Dream Chaser.

The wings on the X-34 were sized and stressed for the powered pitch-up maneuver, which occurred while the vehicle was flying supersonically and still carrying a sizable load of fuel. These heavy wings would let the Dream Chaser survive an abort with a substantial amount of fuel on board, but they were dead weight during ascent and during a nominal re-entry.

Ultimately, it was thermal protection concerns that led to the redesign of Dream Chaser. The new design will encounter a more benign thermal environment when returning from orbit. It's based on the NASA HL-20 lifting body, which in turn was an evolution of the Soviet BOR-4 from over 30 years ago.

BOR-4 was an early attempt by the Soviets at a reusable space plane. Several models of BOR-4 were launched on suborbital jaunts, while the MiG-105 validated that a pilot could land the BOR-4. Ultimately, BOR-4 was dropped in favor of BOR-5, a copy of the US Space Shuttle. Soviet paranoia over potential military uses of the American shuttle led to the multi-billion dollar Energia-Buran program, which greatly contributed to the bankruptcy of the USSR.

After Challenger was lost, NASA looked at BOR-4 (given the NASA name "HL-20," for "Horizontal Landing") as a backup to the Space Shuttle that would provide assured access to the Space Station. While HL-20 was seen as a successful program, it lost funding in 1992 in favor of the crew-rescue X-38. When NASA's doomsday scenario played out in 2003-2005, space station access was provided by the reliable but payload-limited Soyuz.

SpaceDev's concept art shows the Dream Chaser (aka BOR-4/HL-20) straddling three hybrid boosters, in an arrangement similar to the shuttle. A rocket attached to the Dream Chaser's tail will probably provide the needed push for orbital injection, possibly doubling as an escape system.

At this point, I have issues with the escape system. Unless the Dream Chaser was mounted at the top of the launcher, it will be incinerated in the fireball of an exploding booster, and has a good possibility of colliding with the booster if the rocket fails in a more benign way. The ony reason I can see for this arrangement is because the rocket becomes more unstable as the winged vehicle is moved closer to the nose of the booster rocket.

If th boosters are reliable enough, the debate over an escape system will be moot. Time will be the judge of whether SpaceDev's hybrid engines are really necessary for space tourism. While the engines may be inherently safer than liquid engines, their specific impulse is a lot weaker than liquids (and, dependent on the oxidizer chosen, can be worse than solid rockets.) The case can also be made that liquid engines are "safe enough" for manned sapceflight, especially if engine-out survivability is designed into the system.

Thursday, January 05, 2006

Support Your Troops

"I Support the Troops" is a phrase repeated so often, it has become cliche. Each time you see the phrase on a car magnet or a yard sign, what does it mean to you? Is it simply a way of saying, "I don't actively support the enemy"? Words have meaning, and supporting the troops implies that people who do so should go out of their way and physically improve the lives of Soldiers, Marines, Airmen, or Sailors who have deployed to the combat zones.

I remember an interview with Denzel Washington (back when he was promoting The Manchurian Candidate) where he asked the question about what Americans are really doing to support the troops, especially when they come back from combat. We need more people like Denzel to raise the issue, generate support for those called to serve, and improve their morale as they slog through hellish conditions.

When I was training in Alabama, I joined a small group of folks who volunteered for the charity "Serving Those Who Serve." We spent a Saturday renovating the home of a Marine to make the house more accessible to him. This Marine had lost a leg in fighting near Fallujah back in August 2004. He told us parts of his story, like coming off the plane to the states while as high as a kite on pain medication. Yet he never seemed bitter about his service. He was proud to be a Marine, and fortunate to have lost only his leg when his fellow Marines had suffered worse fates.

Although the holidays have passed, there is never a wrong time to serve those who serve. For the fighting men and women who are deployed to the warzone with none of the amenities we take for granted in the US (like beer and adult magazines,) a simple gesture like a care package can make a world of difference. When they come back home, they will still need our love. All real Americans must support their troops--with actions, not empty rhetoric.

Tuesday, January 03, 2006

Marriages of Convenience

PlanetSpace (the sponsor of the Canadian Arrow space tourist rocket) has made some provocative alliances over the past few months. The first deal was an alliance with ARCA Space of Romania. The second is the assistance of hypersonics expert Paul Csysz on the "Silver Dart" orbital vehicle, an adaptation of the FDL-7 lifting body.

Looking at what ARCA Space has accomplished thus far, it's hard to tell what PlanetSpace hopes to gain from this arrangement. To ARCA Space's credit, they have successfully demonstrated a propulsion system and have flown several test rockets. This is a lot better than I can say about many other X-Prize contenders. Yet it should be noted that ARCA Space's engine uses the decomposition of 70% Hydrogen Peroxide rather than the fuel + oxidizer approach of most engines. The peroxide monopropellant engine has a low specific impulse, and has been relegated to reaction control rockets such as those on the X-15 and Mercury capsules.

ARCA has some big plans, such as the air-launched "Orizont" rocket. However, Orizont is a horribly complicated affair with swing wings and an "expendible air-breathing engine." ARCA would be advised to keep it simple. The simplest approach to space tourism is a single-stage rocket that lifts off from the ground, flies above the arbitrary 100 km boundary of space, then separates into capsule and booster segments that parachute to earth separately. This is precisely what Canadian Arrow is doing. Canadian Arrow has made real progress towards a manned capsule and a propulsion system, while clearing many of the legal and logistical roadblocks on the way to launching their rocket. The V-2 that has formed the basis for the Canadian Arrow is a proven design, and while it didn't have the most effecient of engines, it still used a potent LOX-Ethyl Alcohol propellant combination.

The announcement of the "Silver Dart" orbital vehicle struck me as being a bit premature ( I believe that companies should demonstrate their competence before making bold claims, and such an announcement should have waited until the Canadian Arrow actually flies.) However, it demonstrates forward planning and a desire to revisit sound ideas from the past.

In short, an alliance with ARCA Space is the last thing I'd want to pursue if I were the Canadian Arrow team. The deal with Paul Csysz is a bit better, but it will be many years before we see the benefits from this teaming.