Chair Force Engineer

Tuesday, February 23, 2010

Carbon Cycle

The new NASA budget calls for development of a new hydrocarbon engine, similar to or greater in thrust than the existing RD-180, as part of its “Heavy Lift Research” effort. Instantly I’m reminded of RS-84, the large hydrocarbon engine that NASA had funded from 2002-2004 as part of its Space Launch Initiative. After the Vision for Space Exploration was announced, RS-84 lost its funding as it didn’t fit into the lunar return mission. The great opportunity it once presented was wasted, but the industry will pick up where it last left off.

The new engine won’t be exactly the same as RS-84; the old effort aimed at producing a reusable engine in the class of the F-1 that powered the Saturn V. The new engine is targeted at roughly half the thrust.

At the heart of a new hydrocarbon engine will be the complex machinery required for the staged combustion cycle. Past US hydrocarbon (kerosene) engines have used the gas generator cycle; even the F-1 and new Merlin 1e have only produced around 304 seconds of vacuum specific impulse. The Russians, on the other hand, developed staged combustion cycles for the RD-170 family of engines (of which the RD-180 is a member.) This more efficient burning process raises the vacuum Isp to 330 seconds or more. The challenge in perfecting this combustion cycle for hydrocarbon engines is avoiding the “coking” of carbon deposits along engine components where it interferes with operation. Coking is less of a concern for single-use engines than with reusable ones like RS-84, but it still must be mitigated to ensure the engine works reliably during boost.

The history of launch vehicles only validates hydrocarbon engines as a great asset for booster engines. While hydrogen/oxygen propellants have higher specific impulse, the low density of hydrogen means larger, draggier propellant tanks and engines that generally produce lest thrust than their hydrocarbon counterparts. This thrust is extremely important during the first stage of the mission because the rocket is at its heaviest. The thrust needs to be slightly greater than its weight at this point so the vehicle can boost straight up. Thrust becomes less important (relatively speaking) once the vehicle is above the densest layers of the atmosphere and pitches over for the rest of the ascent.

The Space Shuttle used high-thrust solid rocket boosters to overcome the deficiencies of its hydrogen-fueled main propulsion system. Solid rockets can generate large amounts of thrust and have very high density, but their specific impulse is very poor. Hydrocarbon engines seem to "split the difference" between the two extremes of hydrogen and solids. A launcher with a hydrocarbon first stage can clear the launch tower and loft its hydrogen-burning upper stages to an altitude where there's little atmospheric drag, before burning out and falling away.

Since the days of Apollo, the US has largely ceded its lead with hydrocarbon engines. Aside from incremental improvements to the Atlas I/II and Delta main engines, the only significant development has been the Kestrel and Merlin engines developed by SpaceX. The propulsion directorate of Air Force Research laboratory has been working on a powerhead for a kerosene-burning, staged combustion engine for several years; sadly, this effort hasn't been funded at a level that will lead to a flightworthy engine in the near term. The new NASA program will likely build a replacement for the Russian-produced RD-180. America's reliance on Russia for this vital component of the EELV program is a national security vulnerability that will hopefully be corrected in the next decade.

The requirement for an RD-180 sized engine seems to mesh with the heavy-lift options discussed by the Augustine Panel. Jeff Greason's assertion that a heavy lifter should be designed around a 50 tonne payload is borne out by the "Atlas V Phase 2" studies. (Of course, new propellant tanks and new engines means it's not really an Atlas V anymore.) A triple-core vehicle with boosters wider than 5 meters can meet the Greason-defined heavy-lift requirement. Its single-core derivative could launch a 20 tonne payload like the former Orion capsule. Each booster core would require two RD-180 class engines, for six in total on the heavy lifter. NASA had also looked into a bigger, three-stage heavy-lifter based on shuttle ET tooling. Such a rocket would be similar to the Saturn V in performance (possibly even greater) while using only seven RD-180 class engines on its first stage.

I'd expect both Pratt & Whitney-Rocketdyne and SpaceX to compete for NASA funding on the new engine. PWR likely has some knowledge of the RD-180 that can be applied for the new engine. SpaceX has been working on a "Big Falcon Engine" for several years. (I had even suggested at one point in the past that BFE should be designed as a replacement for the RD-180 and for the nine-engine cluster on the Falcon 9.) Whether the new effort will be collaborative or competitive seems unsettled. Also vague at this point is whether the effort will focus on kerosene propellants, or if alternatives like propane and methane are under consideration. (Hank Hill would get excited about the former prospect.) Methane would seem to be better suited for upper-stages and earth-escape stages; it's similar to hydrogen in many ways aside from its higher boiling point.) The involvement of SpaceX begs the question of whether a new engine development program is necessary if SpaceX was going to develop one anyways.

The RS-84 program might have been the best element of the Space Launch Initiative program. It was certainly a step in the right direction, and it ended prematurely after NASA started sacrificing technology development in favor of a single-minded focus on the lunar destination. Hopefully this new effort will receive a much higher funding level and an aggressive schedule. We're back to square one in this effort, but this gives the industry a chance to fix past mistakes and get US booster development on the right track.

Monday, February 15, 2010

The Space Program We Can Afford

Reactions to the "Obama Space Plan" across the industry have been extremely polarized indeed. The debate has drawn in odd defenders of the president and some even stranger opponents. When Newt Gingrich is defending an Obama policy from the attacks of Charles Krauthammer, you know the world has been turned on its ear.

My brief take on the new space policy is that it's the only option our nation can possibly afford at this time. Every day I fret that America is going broke, and sliding into a debt oblivion before anybody realizes it's too late to claw our way back from the brink. Can we really afford "Apollo on Steroids" right now? We certainly can't give the former Constellation program the extra $3 billion per year that it needs simply to meet its baseline schedule. So what we get instead is no system to replace the shuttle when it's retired, an ISS extension to 2020 or later, continued American flights on Soyuz, and a "heavy lift research program."

The reliance on commercial spacecraft is one based in convenience and necessity. It's the most controversial aspect of the new policy and the linchpin of any future plans to travel down the "flexible path." I'm trying to temper my enthusiasm for a commercial spaceflight industry with a realistic outlook on the ability of these companies to deliver a safe and reliable manned spacecraft program. SpaceX and Boeing likely have the experience and knowledge to pull it off, although their schedules are anybody's guess. The other vendors I'm more skeptical towards.

Supporters of the new space policy are asking the White House to set some concrete goals. I'm reminded of Newt Gingrich's idea from the early 90's to create massive cash prizes for private firms who could successfully put a human on the Moon or Mars. Maybe such a scheme could work after one of the aforementioned firms can successfully launched a manned spaceflight mission. But I'm skeptical that the money even exists to create such prizes.

Rather than a NASA that has concrete exploration goals, I predict that the new space policy will make NASA less and less relevant towards achieving national goals in space. Example: The Bigelow vision is space tourism, utilizing space hotels and eventually outposts on the moon. Exploration beyond earth will eventually happen, but it will support commercial goals rather than nationalist ones. NASA will continue to lead in the fields of robotic exploration and pathfinding research & development, but it's hard to see NASA sending humans beyond earth orbit once it surrenders its manned spaceflight capability.

The most befuddling aspect of the new policy, in my eyes, is the need for heavy-lift "research." Wasn't the industry doing heavy-lift research in the 50's and 60's that lead to the Saturn V? If the nation needs heavy-lift, we don't need additional research to do it. A NASA-operated heavy-lifter could even use leftover shuttle SRB's, ET's and main engines for an early demo flight. But until we get more specifics on the new space policy, I'm not confident that's in the cards.

When President Bush first announced his Vision for Space Exploration in January 2004, I originally thought it was a fitting tribute to the fallen astronauts of Columbia. If NASA is putting its astronauts in harm's way, it should do so in support of bold objectives rather than the routine science missions of the space shuttle. But the affordable "marathon, not a sprint" that President Bush called for eventually turned into "Apollo on Steroids." It just wasn't possible to give the Constellation program the massive up-front development budget it needed while still operating the shuttle and space station. (I had been told by a congressional staffer that VP Dick Cheney's staff wanted to retire the shuttles after the Columbia disaster and not return-to-flight until the Crew Exploration Vehicle was ready. Maybe that approach could have saved "Apollo on Steroids.")

Sometimes I think that this new, commercial path is a more fitting tribute to the crews of our lost space shuttles. People will buy their way into space, rather than being selected by NASA to take their chances on a vehicle that was designed by committee. At least the shuttle's days are ending, much to the amazement of virtually everybody who's followed the program since it first flew (they would have expected it to be replaced with a better system much sooner than 2010.)

So do I think the new space program is a good thing, or a bad thing? It's both, and it's neither. It's an acknowledgment that the US Government as a whole is running on empty, and the future is in the hands of the private sector. The plan has even odds of spectacular success or embarrassing failure. That's why SpaceX, Boeing/Bigelow and the others deserve the moral support of the nation. Their success ensures prestige and continued technical competitiveness for the United States. Their failure effectively cedes control of the spacefaring future to Russia and China.

Sunday, February 14, 2010

Project Azorian: More Questions than Answers

Thanks to a Freedom of Information Act request, the CIA has finally admitted the existence of Project Azorian. This was probably the most audacious covert operation during the entire Cold War; at least a small section of the sunken Soviet submarine K-129 was secretly raised from the ocean floor in 1974 by a specially-built salvage ship, the Glomar Explorer.

Up to this point, the operation had been known in the popular press as "Jennifer," rather than "Azorian." When I heard the official name, I immediately thought of the USS Scorpion which sank near the Azores in May 1968. For years, author and naval nuclear engineer Kenneth Sewell has promoted the theory that Scorpion was sunk by the Soviets in retaliation for the loss of K-129, which was blamed on the Americans.

As I've grown older, I've grown far more skeptical of conspiracy theories. When it comes to the case of the USS Scorpion, I think that Stephen Johnson paints a compelling case in his book Silent Steel that Scorpion suffered an undetermined mechanical problem that forced the boat to rapidly sink below crush depth. The Soviets didn't have a good shot at locating Scorpion, let alone sinking her. But the "Azorian" name plants some seeds of doubt in my mind. Maybe the CIA saw themselves as "avenging" the 99 souls lost with Scorpion by retrieving K-129 from the Ocean floor. Who knows? But I have no doubt that Kenneth Sewell will claim this as one more piece of evidence for a larger conspiracy, and sell yet another book on the subject to prove his point.

Wednesday, February 10, 2010

Contract for America's Tanker

Northrop-Grumman is crying "foul" with the Air Force's plans for putting "KC-X," its new tanker aircraft, on contract. The tanker waters have been muddied for years; a deal to lease Boeing 767's was scuttled in 2003 after the Air Force's top procurement official, Darleen Druyun, was caught negotiating for an executive position at Boeing (in blatant defiance of Federal Acquisition Regulations.) Two years ago, the Air Force announced that the Airbus / Northrop-Grumman A330 would become the KC-45 tanker; the plan was dropped again after a successful protest by Boeing.

The seeds of doubt have already been planted about the legitimacy of the third attempt at buying new Air Force tanker planes. For starters, Northrop-Grumman objects to the use of a fixed-cost contract for the aircraft's development. Under the fixed-cost contract, the contractor promises that their development budget will come in at a certain cost. If the contractor exceeds the promised amount, they eat the difference. Fixed-cost contracts are great for the taxpayer, but they put the contractor at great risk. They are largely worthless for major development programs, because it's so difficult to accurately predict the costs for a system that's never been built before. They are best suited for buying additional lots of systems that have already been developed, like munitions and existing fighter jets.

Northrop-Grumman has some history on their side regarding fixed-cost contracts. In 1988, Northrop objected to the fixed-cost contract for developing the stealthy A-12 attack plane. The company withdrew from the contest, and the contract was awarded to the less-experienced team from General Dynamics. GD couldn't meet the plane's ambitious weight and schedule goals, and the contract was terminated in 1991. (Personally, I blame the Navy rather than GD for the program's termination. Between the contractual problems and the Navy's extremely aggressive schedule, it was impossible to see the program succeeding unless the Navy relaxed its requirements.)

DoD also uses "cost plus fixed fee" contracts, which usually guarantee that the contractor will be reimbursed for all work and still make a profit. Unfortauntely, these contracts also enable contractors to game the system. They often propose nonviable but inexpensive solutions so they can win the contract. After the program is secure, the contractor replaces the nonviable systems with more expensive (albeit viable ones) at expense to the taxpayer. There is little incentive for cost control, and contractors who give honest estimates of cost at the onset of the program are usually downselected.

The last type of contract is the award-fee contract, where a percentage of the contract value is awarded based on the government's subjective assessment of the contractor's performance. Of the three contract types, this is usually my favorite for covering development contracts. Yet the award fee is also far from perfect. The government rarely gives the contractors serious penalties for delays or hardware that fails to meet specifications. Awarding less than 95% of an award fee is seen as an insult by the contractors, even if they earned their low scores through poor performance. The award fee contract has merit, but only if the government people are willing to give it teeth.

As far as the KC-X contract is concerned, I am not losing any sleep over the use of a fixed-cost development contract. The tanker variants of both the Boeing 767 and Airbus A330 have already been developed in variants for allied air forces. They are a well-defined quantity. The biggest unknown is the difficulties of the politically-motivated transition of Airbus production from Toulouse, France to Alabama.

Northrop-Grumman does have a legitimate concern that the tanker contract will be awarded based on lowest cost per plane, rather than best value to the taxpayer. The Boeing 767's advantage is that it's not too much bigger than the KC-135's that are being replaced. The A330 is a much bigger airplane that is closer in size to a KC-10. It's also a more expensive airplane to build. I am more sympathetic than many of my peers to the A330 because of my affection for the KC-10 (a very reliable airplane that offloads a lot of fuel to many thirsty jets per mission.) A sound economic argument could be made for buying the A330 on the basis of its cost to refuel a given number of airplanes (using fewer A330's than 767's to refuel the same-sized fighter formation.)

It sometimes seems like the best (and most politically-sound) solution would be a split buy between the two airplanes (at added cost to the logistics chain, which would need to maintain two types of aircraft.) I just hope the Air Force gets it right this time. They can't afford another expensive mistake like the last two attempts at a tanker contract.

Friday, February 05, 2010

A Capsule of Knowledge

Rob Coppinger has an excellent piece about the demise of the Orion spacecraft, complete with pics of the Boeing/Bigelow spacecraft that's being dubbed "Orion-Lite." (Ironically, the cancellation comes just a week after a good friend suggested I should apply for a LockMart job in Denver working on Orion.) He makes a lot of good points about the distinctons between a capsule designed for missions to low-earth orbit versus a lunar-capable capsule. A beefier heatshield, more consumables and radiation shielding, and bigger parachutes are just some of the differences which necessitate a nontrivial redesign for a "Block II" spacecraft that can return from the moon.

But is it necessary to lug the capsule and reentry systems with you on voyages to the moon, Mars or asteroids? Some of Mr. Coppinger's commenters make this point as well. The parachute deployment pyros and heat shields might not hold up well when exposed to the cold vacuum and intense radiation of the space environment for extended-duration missions. If we follow some of Buzz Aldrin's old advice, we'd be flying reusable "cycler" spacecraft to Mars. Such a cycler would presumably aerobrake into orbit around Earth, where a capsule could be launched from Earth to recover the crew. A similar strategy could be followed for a lunar transportation architecture.

The jury is still out on how you'd recover a crew at the end of a round-trip Mars mission. Would they aerobrake into orbit around earth and spend a quarantine at a space station before being allowed to return to Earth? Or is it possible to spread out the deceleration forces from re-entry so that the stresses would not kill a crew that had been weakened by 900 days of minimal gravity? Boeing's 1968 IMIS proposal for sending humans to Mars posited a biconic "Earth Entry Module" to give astronauts a low-G, lifting re-entry. Other plans have ended with retrieval from the space station.

In many ways, Orion was a design tailored for the lunar mission. It was heavier than necessary for space station missions, yet probably not robust enough for a trip to Mars and back without some major modifications. I don't lose too much sleep about its cancellation, and I hope that its commercially-designed replacements benefit from Orion "lessons learned." Regardless, the traditional paradigm of "carry all your reentry systems with you" has its limitations, and it should be rigorously challenged as America feels its way along the "flexible path."

Monday, February 01, 2010

New Directions

I don't have much to say about the new NASA budget projections, aside from noting the bitter irony that they were released on the 7th anniversary of the Columbia disaster. The advantage of "Flexible Path" is a strong incentive for private enterprise to flourish in manned spaceflight; the consequence of its failure is no American manned spaceflight capability. The destinations of "Flexible Path" are equally susceptible to the vagaries of national will, the federal budget, and the capabilities of the private sector.

The new budget doesn't assure that the moon is lost; that was in the cards years ago with the mismatch between "Apollo on Steroids" and a shuttle-sized budget. Apollo thrived because of its front-loaded development budget; Mike Griffin gambled that he could either stretch that development out while still flying the Shuttle, or that Congress would give NASA a budget increase in the neighborhood of 20%. In the end, Congress kept the budget flat, and the timetable for a lunar landing kept getting pushed back to around the same time frame as an appearance in the World Series by the Chicago Cubs.

My hopes lie with the optimistic and upbeat people at firms like SpaceX who are now entrusted with America's future in space. Remember the adage of "Do good work" that drove the space industry during those heady days of Project Mercury. America is back to square one yet again, and her future rests on the shoulders of her industry. The nationalism-driven era of manned spaceflight is drawing to a close. The future has just begun.