Chair Force Engineer

Mike Griffin, Saturn I, and the Potemkin Rocket

2009-10-28T11:43:00.001-07:00

After three years of anticipation, the "Potemkin Rocket" known as Ares I-X has launched. The flight appears to have been nominal. While Ares I-X was a low-fidelity test of a bad rocket design, the test's fundamental flaws should not detract in any way from the Ares I-X program personnel who devoted the last three years of their life to making this test a success. While I strongly believe that Ares I-X should have waited until the 5-segment SRB was available, Ares I-X still taught NASA personnel much about ground handling operations and ocean recovery for the Ares rockets. Perhaps the thrust oscillation questions will look a little bit more clear after the test, in spite of the SRB that was used for the launch being so different from the final SRB.

Ares I-X also serves as a backhanded endorsement of Michael Griffin's approach to Project Constellation. Ares got a foot in the door before Norm Augustine's panel could have the final word. For members of Congress who don't comprehand how much more work beyond Ares I-X is necessary before the real Ares I is ready, the visual of Ares I-X lifting off is evidence that the program is on track. Indeed, mebers of Congress are already spinning the Augustine Report as evidence that Ares is being well-executed, even though the committee largely ignored that question (and largely endorsed the idea of commercial spacecraft for low earth orbit missions, with Ares V Lite for deep space exploration.) Somewhere, Mike Griffin is smiling with glee. Not just because Ares I-X succeeded, but because the political winds growing across the Potomac will keep his Shaft Rocket airborne for the forseeable future.

When I think of Ares I-X, I start to think of the original Block I Saturn I rockets. (This is as flattering to Ares I-X as it is insulting to the Saturn I.) The four Block I flights flew with no fins, a dummy upper stage, a shortened first stage and less powerful first stage engines than the later Block II Saturn I and Saturn IB. It would be possible to look at the original Saturn I's and say they contributed nothing to the final man-rated Saturn IB. But that misses the point entirely. After the successes of the first Saturn I's, it was fairly easy to tweak the H-1 engines and stretch the propellant tanks. Even the redesign of the tail fairing wasn't the biggest challenge in the Saturn I evolution. Block I retired the risk on the first stage; Block II tackled the challenge of the new liquid hydrogen upper stage. Saturn IB went a step further by testing the new upper stage engine that would also take men to the moon. But Ares I-X didn't accomplish any major risk reduction, since the only hardware commonality is the SRB case segment design.

The Ares I-X test doesn't tell us much about the ultimate success of the Ares I program. But because the test did succeed, we know that the riddle and challenge of Ares will carry on.

Controlling the Platform

2009-10-23T15:47:00.000-07:00

For once in my life, I'm actually excited about upgrading to the new version of the Microsoft Windows operating system. After the major embarrassment of Windows Vista (which could never shake the somewhat-true perception that it was bloated and slow) comes a refined, streamlined Windows that breathes new life into computers from the 2003-2004 time period. I'll probably take advantage of the upgrade after I stick more RAM in my custom tower PC. I'll even forgive Microsoft for the fact that the new OS carries the confusing name "Windows 7" when it should be "Windows NT 6.1."

At the same time, the Mac fans are using the new Windows rollout to justify the fact that they've had a rock-solid OS for years. The Mac OS X family is based on BSD UNIX and benefits from the fact that few virus-writers want to spend their time attacking systems that only 11% of the population use.

If Mac OS is so great, why doesn't Apple release it for everybody to run on their PC's? It's theoretically possible, since the Mac platform migrated to Intel CPU's back in 2006. But Mac OS for Intel-based systems still requires Apple's firmware on your motherboard in order to run. Apple is primarily in the business of selling hardware, not software (Microsoft's business model is the exact opposite.) In Apple's view, having a good OS helps to sell hardware. (Intel's thinking isn't very different, as every Windows upgrade helps Intel to sell the more powerful hardware that the new Windows requires.)

With the brief exception of the mid-90's Mac clones, Apple has maintained exclusive control of the Macintosh platform. Is that a good business model for the PC industry? The conventional wisdom is that the openness of the Intel-Microsoft architecture has been good for the PC industry as a whole. But it may not be good for the individual PC manufacturers. Case in point is IBM, who pioneered the architecture we're familiar with today. "Big Blue" was beaten to the punch when Compaq introduced the first 386-based PC in 1986, and eventually quit the home PC business when it sold out to Lenovo.

It's debatable if IBM could have maintained its position as a market leader if it had adopted the 386 CPU earlier (which it didn't, because Intel refused to let IBM produce its own 386 chips under license.) But that point marked IBM's slide from being an innovator into being an also-ran. From that point on, it was clear that Intel, not IBM, would dictate the future of personal computing.

One of my favorite PC "what if" scenarios is the Commodore Amiga. When the Amiga platform was launched in 1985, it was easily the most advanced personal computer available, capable of pre-emptive multitasking and stunning color graphics with as little as 256 kilobytes of RAM. It was even priced competitively (nearly half the cost of the inferior Macintosh models of the day.) Yet Amiga never caught on like the PC or Mac. It was partly due to Commodore's reputation for producing low-cost computers aimed at the children's video game market, and partly due to an inept marketing department. But it's debatable whether Amiga clones could have saved Commodore from its 1994 bankruptcy. While Commodore could have made money selling its Amiga OS to owners of Amiga clones, Commodore was always in the business of selling computer hardware. Amiga clone computers would have likely taken away sales from Commodore.

It's been said that the Macintosh platform currently controls 11% of the personal computer market. Different flavors of Windows control nearly 90%, and Linux has around 1%. (I don't know if that figure comes from recent sales numbers, or surveys of individuals to see what computers they use at home.) While that might not sound good for Apple, it's pretty remarkable to think that the Apple hardware has an 11% market share. Just think of how many other PC makers dominate the market--Dell, HP, Gateway and Toshiba, just to name a few. I'd be interested to look at the total sales volume for the PC vendors to see where Apple stacks up. It's clear that the company is doing very well for itself.

All things considered, Apple's exclusive control over the Mac platform is good for the company. And regardless of whether your computer runs Mac OS or Windows or even Linux, it's likely that Intel is laughing all the way to the bank.

The World's Largest Stick of Dynamite

2009-10-20T18:52:00.000-07:00

Just when it seemed like the history books had been closed on the Challenger disaster, I came across a review of Truth, Lies & O-Rings, an interesting look at the faulty decision-making leading up to launch. (hat tip to Clark Lindsey's Hobbyspace.) The reviewer makes an interesting point about the dangers inherent in ground handling of solid rockets. Many of the inherent disadvantages of SRBs have been long-discussed, such as the inability to shut them down during abort situations. But handling and storing the motors carries all the potential dangers of riding on them. For that reason, SRB stacking operations are classified as “hazardous operations,” and all non-essential personnel are banned from the Vehicle Assembly Building. The procedure is similar for stacking the stages of other solid-fuel launch vehicles. In spite of all the precautions and built-in safety mechanisms, the potential always exists for a catastrophic solid-fuel detonation, as occurred with Brazil’s orbital launch vehicle.

While I tend to think that the risk is overstated (the industry has been dealing with large solid rockets since the 1940’s,) it can never be entirely eliminated. For this reason, Jeff Bell predicted that the SRB would be deleted from the shuttle-derived launch vehicles under development by NASA. Many “space boosters” are dismissive of Jeff Bell, viewing him as a cynic whose arguments aren’t worth the paper they’re written on. I’ll concede that his predictions often come with fatal flaws, but he does make a lot of solid arguments and presents plenty of pertinent facts. In the case of the aforementioned prediction, Jeff Bell’s fatal flaw is assuming that NASA would choose a safe, clean-sheet launcher design over one that protects the shuttle’s entrenched workforce and contractors.

The ground-handling of large solid rockets (and even the individual segments) was an issue that should have been re-examined when Ares I was designed to be "safe, simple and soon." While NASA personnel have done an admirable job in handling the SRB's up to this point, it's sobering to know that just one mistake could cost a lot of lives and pull the plug on the nation's manned space program. The Ares 5-segment SRB will be the world's largest stick of dynamite, and that risk should never be lost on anybody who works in the space business.

The Other Engine

2009-09-25T23:19:00.000-07:00

Whenever I check my gmail account, I see these odd adds from General Electric telling me that I should petition my congressman to continue funding for their F136 turbofan engine. While appeals to the public rarely have the desired effect in defense acquisition, it does raise an interesting point. The F136 program is an unprecedented development in military aviation acquisition: it's the first time that a major weapons system (the F-35 Lightning II) has been authorized with two separate engines before the first flight.

General Electric makes its argument based on their experience producing the F110 replacement engine for the F-14 Tomcat and F-16 Fighting Falcon. Yet the F110 was the product of unique circumstances that are not present in the development of today's F-35 fighter jet and its F135 engine, produced by Pratt & Whitney.

The F110 story actually begins before 1964, when Pratt & Whitney produced the first low-bypass turbofan engine for supersonic fighter aircraft. The TF30 was eventually fitted to the F-111 supersonic medium bomber, F-14 Tomcat (a carrier-based fighter,) and the A-7 subsonic light bomber. All three of these aircraft suffered from engine reliability problems. The F-111's problems were least severe, and the aircraft still flies (in the Royal Australian Air Force) with its original engines. The A-7's performance with the TF30 was so poor that Allison Engines produced a license-built version of the Rolls-Royce Spey to replace it during future production models of the A-7. For the Tomcat, which suffered most from compressor stalls, a replacement engine would have to wait until the late 80's.

The situation was not much better when Pratt & Whitney designed the F100, a fighter turbofan that was well ahead of its time when it first powered the F-15 Eagle in 1972. The engine's reliability problems were less pronounced in a twin-engined aircraft like the F-15, but they became much more critical when the engine was used in the single-engine F-16.

General Electric came to the rescue with a derivative of the F101 turbofan designed for the B-1 supersonic bomber. With some modifications, the F101 was adapted into the F110 fighter engine. The new engine became the powerplant of choice for future F-14 and F-16 production, and was retrofitted to older F-14's. Interestingly, both the F100 and F110 will power South Korea's version of the Strike Eagle (F-15K.)

Having an alternative engine waiting in the wings was a great blessing to both the F-14 and F-16. General Electric reasons that they will be the savior for the F-35 program too. The problem for GE is that the two situations are very different. The TF30 and F100 were designed when supersonic turbofans were still in their infancy. By contrast, the F135 baseline engine for the F-35 draws on mature propulsion technologies developed for the F119 engine in the F-22 Raptor. The chance of F135 becoming a dud like the TF30 or F100 are far slimmer. While the F136 ensures two engine vendors for the F-35, it's a very expensive option for the defense department to retain. It seems like an expensive bailout of GE to keep two major fighter engine manufacturers in business, more than anything else.

Turn on the lite

2009-09-18T11:16:00.000-07:00

One curious recommendation of the Augustine Commission is their preference for "Ares V Lite," a proposed heavy-lift rocket which would fill the gap between Ares I and Ares V and be capable of launching the manned Orion spacecraft. When compared to the baseline Ares V, the "Lite" version can only lift 140 tonnes to the reference orbit instead of 160 tonnes. Bear in mind that even the "Lite" rocket has more performance than the legendary Saturn V.

With so little information in the public about Ares V Lite, it begs the question of that makes this new rocket so "Lite" when compared to Ares V? Because the Ares V baseline had switched to a 5.5-segment SRB (with a dummy spacer, to allow for an even longer core,) my guess is that "Ares V Lite" will use 5-segment SRB's similar to the one tested by ATK last week.

It's also possible that the "Lite" core stage is shorter, with the SRB attach points moved further aft on the SRB. This is necessary so the SRB cross-member can pass between the LOX and hydrogen tanks through the intertank structure.

The upper stage probably didn't shrink by much, because the propulsion requirements for escaping low earth orbit are similar (depending on whether Altair and Orion have changed in mass.) The biggest change is whether the upper stage is still expected to accelerate from Mach 12 to orbit, or if the staging velocity has changed. My recommendation to the Ares team is to invest any mass savings from the total system into systems which will reduce the upper stage's on-orbit boil-off, allowing it to loiter for a longer period of time.

My biggest question to the Ares V team is about the number and type of core engines. The baseline Ares V had six RS-68B engines. But if heating from the SRB's is an issue for the core engines, this is all subject to change. A regen-cooled RS-68R, or expendible engines based on the Space Shuttle Main Engine, might be better suited to surviving the thermal environment. They would also improve the overall performance of the rocket, at the expense of reduced thrust. Switching to regen-cooled engines results in a smaller core stage (either shorter or narrower, depending on the whims of the team at NASA-Marshall) carrying less fuel. Depending on how much lighter the core stage gets, the reduced thrust of expendible SSME's might not be an issue.

Ares V Lite might be moot if NASA doesn't see the $3B/yr budget increase requested by Augustine 2.0. Nevertheless, it would be interesting to see what Marshall cooked up, and whether it could live up to its performance estimates.

The Shape of Things to Come

2009-09-10T00:16:00.000-07:00

A lot of Constellation critics (particularly those who have singled out the Orion spacecraft) have questioned why we're going back to the Apollo shape for the capsule which will return astronauts to earth when the mission ends. Why not go back to the Soyuz shape? For that matter, can't we examine the shape of the Mercury/Gemini capsules, or come up with something new?

While some might attribute the Orion shape to romancing the past, there's one very good explanation for the reason why Orion looks like Apollo. It's because NASA and the industry have an extensive database of thermal and aerodynamic data on the Apollo shape, based off the capsule's performance during the Apollo program. Most importantly, this includes data from re-entries at lunar flyby and lunar return velocities.

Could the Soyuz shape make for a good lunar spacecraft? The answer is yes, if history serves as a guide. Soyuz-derived capsules flew around the moon during the Zond program, which was supposed to put a Soviet Cosmonaut around the moon before its cancellation. At one point, the Soviets looked into an upscaled, reusable version of Soyuz. Named Zarya, the new capsule would have fit within the 15 tonne estimate for a multi-man capsule equipped for low earth orbit missions. But one possible drawback to the Soyuz "headlamp" shape for future American capsules is whether American agencies and engineering firms could access the full database of thermal and aerodynamic data that the Russians have accumulated over the years. Without full unfettered access, there will be a significant hurdle to reusing the Soyuz shape.

The last viable option is the shape pioneered on Mercury and used again for Gemini. A favorite of the armchair engineers is the proposed Big Gemini, which seems to meet most of the Orion requirements and weighs in under 16 tonnes. While American firms have access to the data generated on these missions and during the development of these capsules, there's no real-world data for how these capsules behave when returning from lunar trajectories at the velocities these trajectories dictate. Perhaps McDonnell did this analysis during the 60's, but nothing beats real flight-test data. Additionally, I'd be interested to see how Big G compared to Apollo in terms of crew volume available to each astronaut. While Apollo was cramped, it was still quite an improvement over Gemini where each astronaut was prettymuch confined to a seat for up to two weeks.

Interestingly, it would appear that the SpaceX Dragon stays true to the basic geometry of the Gemini spacecraft. I don't have exact figures to see if the cone angle on Dragon is the same as on Mercury/Gemini, but they both capture the "tall cone" profile. Dragon also corrects a big problem that I saw with Big G: the awkward docking system. Since Dragon is designed from the ground up and doesn't incorporate any Gemini legacy systems, it is free to contain a docking tunnel in the "nose" of the spacecraft. Big G would have required an additional set of aft windows for docking, and introduces the risk that hot plasma could enter through the heat shield hatch during re-entry.

One last shape worth considering was developed during the CORONA program. Again, this would need to be subjected to rigorous analysis before it was ready for a lunar flight program.

It's not so easy to qualify a new shape for a re-entry capsule, especially if it's going to be returning from the moon. Re-inventing the Apollo capsule might not be the optimal solution, but it's fast one that gives the space program a proven result.

Orion Revisited

2009-09-03T22:52:00.000-07:00

Let's assume for a minute that the post-Augustine national space policy emphasizes the commercial development of a human spacecraft to replace the space shuttle. Obviously SpaceX has the inside track with Dragon, which might be capable of manned flight by 2012. But where would this leave Orion in the grand scheme of things? It might continue at a reduced funding level as a backup to the commercial capsules, but some strategic decisions by Lockheed Martin (and perhaps Bigelow Aerospace) might put Orion back on track to thrive in the commercial space market.

Unlike it's intended Ares I booster, the Orion spacecraft is a generally sound idea. It's rooted in mature technologies and design concepts that would assure safe human return from the moon. (A biconic design might be better for returns from Mars, but there's a lot of controversy about which shape is best for the Mars return vehicle, and how far off that objective really is.)

Orion's problems up to this point have stemmed from NASA's shifting requirements. Until Ares I flies (if that happens at all,) the booster's performance (and Orion's mass budget) are uncertain. The original Orion specifications called for a maximum of six passengers, the ability to operate autonomously in lunar orbit, enough consumables to support four humans during a lunar round trip, and landings on terra firma. The new Orion specifications are for a four-passenger capsule that will likely maintain a pilot while in lunar orbit, and will land in the ocean at the mission's conclusion. Even the capsule's diameter changed, shrinking from 5.5 to 5.0 meters early in the design cycle.

Orion's mass budget always seemed optimistic in my view. The Apollo capsule, designed for a maximum crew of five and sized to a 3.9 meter diameter, weighed in around 30 tonnes in its lunar variant (although the earth-orbit missions loaded less propellant and consumables, weighing in under 15 tonnes.) The mass target for Orion was under 23 tonnes, even though it was sized for 5 meters diameter. Mass savings can be attributed to less propellant (Orion doesn't perform a lunar orbit insertion burn) and using solar panels instead of fuel cells.

Maybe these mass savings offset the added mass of the larger capsule when comparing Orion to Apollo. It's hard to say from my "Monday Morning Quarterback" chair. But it does seem safe, based off the Apollo experience, that a 5-passenger capsule with lunar-capable heat shield would weigh in just under 15 tonnes when configured for missions to the space station. Previous NASA estimates for comparable capsules, conducted during Mars design reference mission studies, came up with a mass under 10 tonnes. This lines up pretty well with SpaceX's estimates for the mass of a fully-loaded Dragon.

With all that being said, LockMart's work on Orion up to this point is far from a waste. If nothing else, LockMart should press on with its own money to get a commercial version of Orion flying (if the commercial capsule option comes to fruition.) Bigelow Aerospace has already proposed "Orion Lite" to launch on an EELV by 2013, but it's unclear if this idea has any official support from Lockheed Martin. And it's clear that for Orion to be commercially-competitive, it will need to fly in a "lite" version without all of the lunar frills.

A commercial Orion would need to keep its mass low, to fit on existing commercial launchers. Even if the capsule was scaled back to Apollo's 3.9 meter diameter, this may still be a tough order. After all, the "Zero Base Exercise" from the 2007 time frame cut Orion back to dangerously low redundancies in critical systems. Redundancy was only restored if extra performance squeezed out of Ares I freed up the mass budget to put it back in.

At the same time, a commercial variant of Orion would be free from NASA's fickle whims and requirements creep. There's no reason not to touch down on dry land. Soyuz has been doing it for over 40 years, thanks to six braking rockets in the capsule's heat shield. Orion could also move to two rows of seating and add more paying passengers (something currently banned under NASA's human-rating requirements, although it's featured in commercial capsule designs like Dragon.)

In short, commercializing Orion would give Lockheed Martin a head-start in the race for commercial orbital spaceflight and make for an interesting race between Orion and Dragon. But Orion would need to go on a massive diet, and the commercial Orion would be a very different beast compared to today's Orion designs. Ultimately it's in America's best interest to have at least two commercial capsules in operation, and it would be exciting to see Orion continue on in this fashion.

Unexecutable

2009-08-24T15:48:00.000-07:00

The biggest conclusion from Augustine 2.0 can be boiled down to one word, an unfortunately common one in the world of big-budget acquisition programs:

Unexecutable.

In short, we can't get there (the moon) from here. The "program of record," (i.e., Ares I&V, Orion & Altair,) can't be accomplished on the existing budget.

Of course there will be a political dimension to all of the fingerpointing that results from this conclusion. Critics on the left will blame Bush for not giving his vision an adequate budget. Critics on the right will accuse Obama of "throwing in the towel" in some non-existent moon race with China when he likely tells NASA they'll have to survive on their existing budget.

Plenty of fingers will point towards Mike Griffin and the people who worked directly for him, for pitching an unsustainable architecture. There's no doubt that ESAS was needlessly expensive, and plenty of cheaper alternatives existed. But Griffin's critics can't say with any certainty if their alternatives could have been fit within the existing budget. ESAS was colossally unaffordable, while something like DIRECT or EELV might have been marginally unaffordable. In the end, we're still not going to the moon anytime soon.

The one area where there's no excuse for either Mike Griffin or Sean O'Keefe is the gap between shuttle and Orion. The historical example of Apollo should have convinced both NASA administrators that capsule development would be a seven-year effort. If a contract for Orion were awarded in late 2004 (a reasonable amount of time after President Bush's January 2004 speech setting a goal of 2011-2014 for Orion,) we might have a manned capsule by 2011. Even with the Orion contract being awarded in 2006, first manned flight by 2013 would have still been realistic--if the capsule's requirements weren't continually shifting with each setback in the development of the Ares launcher. If the capsule people had a stable set of requirements they were working towards (i.e., the established performance of the Delta IV Heavy,) we wouldn't be seeing the gross schedule slips we've seen in Orion's Initial Operational Capability date up to this point.

Every time I talk to my friends within the aerospace industry, I hear the same set of doubts about why we're "wasting money" by paying NASA to launch humans into space. There's a growing sense among the public that there are diminishing benefits on earth for all the money the taxpayers spend on space activities. I'm certain that many people who used to support NASA are growing increasingly dismayed by the "competency gap." The agency has lost the ability to duplicate so many of its past triumphs.

Maybe the solution to all of NASA's ills is to hurl more money at its problems. But if the agency can't demonstrate why it can be trusted as a good steward of taxpayer funds, and why it's still relevant in the face of private-sector space programs, does it deserve the extra bucks?

Capsule-snatchers

2009-08-21T13:07:00.000-07:00

The fun in a James Bond movie lies in the way it can take the classic James Bond formula and put a fresh twist on it. Example: in most Bond movies, Agent 007 saves the world and gets the girl by the end. In 1965's Thunderball, James Bond and the girl are seemingly stranded in a raft in the middle of the ocean after a climactic battle aboard a yacht. Never fear, as Agent 007 always has a gadget from Q-branch to come to the rescue. In this case, he inflates a balloon tethered to himself and his damsel. On cue, a modified B-17 swoops in and snares the hero and heroine using a cable-catcher on the aircraft's nose.

What does this escapist Bond-fantasy have to do with spaceflight? Well, it's a flashy way of demonstrating the technique of midair recovery for spacecraft. After much trial-and-error, it was perfected for snatching re-entering film canisters, descending under parachute. Mid-air recovery is one thing for tiny film capsules. It's quite another matter to attempt it with a manned capsule, or a recoverable engine module. Yet Bigelow Aerospace wants to try the former, and United Launch Alliance is proposing the latter.

In principle it's not difficult, but it creates challenges for the aircraft involved. In the case of large objects descending under parachute, the suspended load mustn't be carried too far off-center, or it will create a situation where the aircraft is fighting a steep bank. It also creates an asymmetric drag force, greatly impeding the aircraft's top speed and adding pitch and yaw tendencies. The aircraft selected for the mission will need to be capable of flying with the payload mass of the object being captured. Even still, the aircrew will notice an immediate loss in altitude and airspeed when the capture is made, as well as a downward pitching moment.

The size of the aircraft making the grab is important. Just as airplanes like the C-119 were unaffected by catching tiny film canisters, a larger airplane will be required to snag larger capsules. I can't give some kind of first-order guess as to which airplanes would be suitable for the midair recovery mission, but the Bigelow trade study will definitely give us an answer.

While avoiding a water landing is desirable, it's still a necessary contingency to plan for. In the event of an abort from existing launch sites, the spacecraft will splash down in coastal waters. A flotilla will still remain on standby, even if midair recovery is the preferred option. If a flotilla is required for launch aborts, it's worth keeping around in case midair recovery fails.

Midair recovery for booster engines is a good idea, because exposure to saltwater could be fatal to any attempts at engine re-use. It's certainly worthy of study for manned capsules, because it spares the astronauts the possibility of being exposed to frigid Atlantic waters which could potentially sink the capsule before the astronauts could be rescued. But the launch abort issue ensures that the recovery flotilla isn't going away anytime soon.

Cool the engines

2009-08-18T15:50:00.000-07:00

Pratt & Whitney Rocketdyne, already busy upgrading its proven RS-68 engine on the Delta IV, may get even busier depending on which direction the Augustine Committee and the president decide to go with Project Constellation.

The current evolutionary roadmap for RS-68 goes to RS-68A, funded by DoD to improve performance for the Delta IV Heavy and eventually the entire Delta IV fleet. By upgrading the turbopumps for higher flowrates, PWR will put more injectors into the thrust chamber of RS-68A to improve thrust and specific impluse (raising from 409 sec to 414 sec in vacuum.)

NASA's current roadmap relied on a further upgrade of RS-68, the RS-68B model, for the Ares V super-booster. The NASA-funded upgrade would increase the engine's redundancy in certain systems (required by the current man-rating rules, and a focal point of the Delta IV crew-launch studies) and reducing the amount of gas that collects at the launch pad prior to ignition.

Yet the findings of the DIRECT team prior to unveiling DIRECT 3.0 may put a wrench in NASA's plans. Their studies (and apparently NASA's internal studies confirm this) indicate the current RS-68 engines will not survive the extreme heating environment nestled between two SRB's. The baseline RS-68 is ablatively cooled, and apparently only a regeneratively-cooled engine can tough it out. The DIRECT team settled for throwing away SSME's as their core engine, believing that this was more cost-effective than developing the proposed "regen" RS-68R. But as I've argued in my previous post, SSME's that are designed for low production costs will be very different from the baseline SSME.

A regen nozzle for RS-68 is simple in concept. Keep the inner mold line the same (to preserve the expansion ratio,) and manufacture the nozzle from thinner stock (since the extra thickness won't be needed for ablating away during ascent.) Mill some cooling channels into the outer nozzle, then braze a thin cooling jacket over the top. Ironically, I'd suspect that the baseline RS-68 shows slight improvement in Isp the longer it burns, because the expansion ratio increases as more material is burned off the inner surface of the nozzle. RS-68R will not experience the same effect.

The turbopumps need to be analyzed to ensure they can pump enough cryogenically-chilled propellant through the coolant channels. RS-68 already employs regen cooling in the combustion chamber, so adding it to the nozzle shouldn't be a huge challenge. Still, this may require a further upgrade beyond what's planned for RS-68A's turbopumps. Previous studies of RS-68R, with the same expansion ratio as the current RS-68, show an Isp improvement from 409 sec. to 419 sec.

RS-68R is definitely a step in the right direction for improving the engine's mass, durability and performance. Still, it falls short of the SSME's 453 second Isp. A longer, wider nozzle would improve specific impulse, at the expense of lower thrust. Regardless of whether RS-68R's nozzle ever reached the expansion ratio of the SSME, I'd never expect to duplicate SSME's specific impulse. After all, SSME makes use of the more complex staged combustion cycle, and has a much higher chamber pressure. Still, it's not unreasonable to expect an Isp around 430 seconds for RS-68R if the nozzle is redesigned to a higher expension ratio. This is an estimate for how the proposed Space Transportation Main Engine would have performed; it would have used an expansion ratio somewhere between RS-68 and SSME, had a chamber pressure between those two extremes, and used RS-68's gas generator cycle.

At the end of the day, NASA-Marshall will have some big decisions to make, and the trades should be backed up by something more substantial and detailed than a 60-day study. Will it be more cost-effective to develop expendible SSME or RS-68R? And if RS-68R is cheaper to develop, procure on a unit basis, or both, will those cost-savings be offset by the engine's lower efficiency when comapred to expendible SSME? The last metric can be quantified with the additional number of launches that will be required to put the same payload mass in space.

Shuttle-Derived Devil's Advocate

2009-08-11T21:18:00.000-07:00

The Augustine Commission, appointed by the president to chart the future of NASA manned spaceflight, is looking at a variety of missions and boosters for the future direction of Project Constellation. One dark-horse concept that's gotten a lot of attention lately is a side-mount shuttle-derived rocket, which I think of as "Son of Shuttle-C." It's definitely an improvement over the existing Ares designs in terms of its development costs and schedule. But much like the rush to Ares, in which issues like thrust oscillation and air-starting SSME's were swept under the rug, it would be helpful to look at all of the challenges that will face the team developing the new rocket.

It's important to distinguish the new concept from the original Shuttle-C proposal. instead of flying the shuttle orbiter, Shuttle-C made use of a "cargo element" which looked much like an orbiter stripped of its cockpit, wings and tail. But the new design utilizes a much larger payload fairing, nearly as wide as the external tank. With a much wider cross section, the new rocket will be a "draggier" design than the existing shuttle or Shuttle-C.

Another thorny issue will be the separation between the new rocket's fairing and external tank. The fairing is supposed to jettison during ascent, with the exception of the aft thrust structure and the connected structure which supports the payload. There should be some concern about achieving a clean break when the fairing jettisons, although it shouldn't be much more dicey than when the SRB's are cast off. In the block I version of the new rocket, the thrust structure and payload structure would separate in the same fashion as the shuttle orbiter. I would guess that the payload would eject parallel to the vehicle's yaw axis, similar to the way the shuttle deploys its payloads.

The separation issue gets riskier on the block II rocket, where a live upper stage is carried inside the fairing. The upper stage ignites suborbitally at a speed just under Mach 17. I would be very concerned about recontact between the upper stage and either the payload structure or the ET.

The "Son of Shuttle-C" promises low development costs for as long as we have spare Space Shuttle Main Engines to throw away when the orbiters are retired. But the new challenge is creating a version of the SSME which can be economically thrown away after every mission. While promoted as an upgrade of the SSME, it's really an extensive new development (moreso than developing the RS-68A from the existing RS-68.)

There already was an expendible Space Shuttle Engine: it was called RD-0120, and it was developed by the Soviets for their own shuttle system. It pioneered the "channel wall" nozzle concept which would drive the production cost of SSME down if it were adopted. But do the Russians still have the tooling and industrial knowledge to build more RD-0120's? Is it practical and politically feasible to buy RD-0120's from Russia? The answer to both questions is probably "no." But it would be worth consulting with them when designing a new SSME nozzle. RD-0120 achieved a similar specific impulse to the SSME, but it required a higher expension ratio nozzle and produced less thrust.

A channel-wall nozzle, designed to the same expansion ratio as the existing SSME, can’t be developed overnight, although Wayne Hale has stated that the idea has been given some consideration in the past. Channel-wall nozzles are far easier and cheaper to manufacture than the existing shuttle nozzles, which use thousands of tiny tubes welded together to form the nozzle wall. Instead, the coolant channels are milled into a solid piece of metal, with a thin sheet of brazed over the top of the channels to seal them off.

Current Shuttle PM John Shannon also stated that the turbopumps would have to be redesigned for making a cheaper, throwaway SSME. Again, this isn’t a trivial modification. I have to wonder aloud whether it might be possible to substitute the expendable turbopumps from the RS-68 (which are designed for higher flow rates than those on SSME.)

When it comes to "Son of Shuttle-C," I don't think it's a bad idea, if your goal is to preserve the "Central Florida Economic Stimulus" that the shuttle program provides. But it will not be a trouble-free or inexpensive development; as long as NASA and the taxpayers keep that in mind, it should result in a workable launch vehicle. Everybody should be warned that an expendible SSME will be a very different beast from the current SSME, and developing the new engine may force the taxpayers to look back on the program with bitter feelings about what was supposed to be a quick and economical program to close the post-shuttle gap.

Abort, retry... fail?

2009-07-29T17:17:00.000-07:00

In response to my earlier post about man-rating the side-mount shuttle-derived rocket, NASA is dead-serious about putting humans on its side-mount heavy-lift launcher. Thanks to NASA Watch, we can now take a look at the agency's analysis of the side-mount abort situation. An initial study of the problem reveals no show-stoppers. As the days go by, side-mount is looking like a better alternative to Ares (assuming we are forced to accept a NASA-designed, NASA-operated launcher.)

At the same time, analysis of Ares aborts by the Air Force's 45th Space Wing at Cape Canaveral has led many engineers to believe this is a show-stopping issue for Ares I. I’m not ready to throw in the towel on Ares without more detailed analysis of the abort problem, but it's a vivid illustration of why solid rocket boosters pose such a challenge for manned launches.

Most Ares critics are focusing on a catastrophic failure of the Ares SRB which would immolate the Orion spacecraft in a cloud of burning fragments. Solid rocket boosters rarely blow up, but they create spectacular explosions and tragic results when they do. Two Titans suffered SRB explosions in recent memory: one in 1986 and another in 1993. The explosion of Brazil's VLS-1 solid rocket on the launchpad in 2003 killed 21 people and dealt the Brazilian space program a major setback.

The Challenger disaster was not the result of a catastrophic failure, but a similar O-ring burnthrough would still give Ares I’s guidance system fits as it struggles to keep the vehicle on course while being torqued by the hot blowtorch escaping from the failed joint. The most likely scenario for the Ares abort system would be escaping the cloud of hot fragments created if the range safety office had to destroy an off-course Ares. Range safety would probably have the luxury of a few seconds between the time when the capsule’s escape motors fire before sending the destruct command to the booster. Depending on how powerful the abort motor was and how much time they allowed, it’s possible for the Ares escape system to get the capsule high enough and downrange far enough to avoid the hot shrapnel that would doom the crew. Then again, this requirement would already add to the massive rocket which would allow Orion to out-run a thrusting Ares.

Much could be learned from the Challenger disaster in terms of how long range safety could wait before triggering the destruct sequence, and how big the debris cloud would become during the period of time Orion would be passing through its abort and descent sequence. Range safety waited what seemed like a long amount of time between the main vehicle breakup and the ground-commanded destruction of the SRB’s. I can't say if the crew module was subjected to an extreme thermal environment before slamming into the ocean. But this may be irrelevant, since the SRB's were quite some distance removed from the crew module before the SRB's were destroyed.

Taken together, all of the challenges going into the design of the Ares abort system demonstrate the compound problems created by the solid rocket first stage. The escape systems on Mercury, Apollo and Soyuz were far less challenging to design and test. They anticipated a shutdown of the liquid-fuel engines on the booster before the escape rocket fired. On a solid rocket, the only premature shutdowns are the ones caused by catastrophic failure. If there’s a need to abort, the astronauts had better hope their escape rocket can get them out of there in a hurry.

From the Earth to the Moolah

2009-07-16T19:48:00.000-07:00

For everybody contemplating the 40th anniversary of the Apollo 11 landings, I recommend heartily this retrospective by Ronald Bailey. In a world where "No Bucks" means "No Buck Rogers," Project Apollo was a grandiose feat, but one that could not be justified with sustained funding levels. "Flags and footprints" served the important geopolitical goal of demonstrating that a free society could be technologically superior to a totalitarian one. Once that goal was met, neither scientific curiosity nor heroic adventure could justify the expenses of further human lunar missions.

As a simple math equation, the Moon represents a goal to which the nation sinks its funds. Out of the moon come tangible and intangible benefits like scientific discovery, inspiration, and consumer spinoffs of space-related technologies. But even when taken together, these benefits of lunar exploration are hard-pressed to qualify as a return on investment on the funds that are spent on human lunar missions.

The answer to a sustained human lunar program is a capitalist approach in which profit is the primary motivation. Perhaps tourism or Helium-3 mining will motivate humans to return to the moon to stay. NASA may have paved the way, but firms like SpaceX and United Launch Alliance will be there to stay. We may not see the financial motivations for lunar exploration develop in my lifetime (and I stand a good chance of making it past 2040.) But all good things happen when the time is right, and when society is mature enough to handle their consequences.

There will always exist the cold warriors whose motivations behind Project Constellation mirror those of the Apollo cold warriors in racing the Soviets. This time the specter of Communist China is the new boogeyman. In spite of a methodically-paced human spaceflight plan and the lack of lunar hardware development, many people see imminent lunar ambitions behind China's current manned space efforts. Perhaps China will land a human on the moon during my lifetime. But any Chinese lunar effort that fails to learn Apollo's lessons is doomed to the same fate. If the Chinese Politboro no longer sees an overriding political goal in lunar exploration, they'll quickly view a human lunar program as a money pit from which they'll inevitably flee.

You aren't going to stick people on that thing, are you?

2009-07-11T07:26:00.000-07:00

During the Augustine Commission hearings, the side-mount, shuttle-derived vehicle has emerged as a surprising dark horse. Compared to Ares and even DIRECT, a side-mount can be developed quicker and cheaper than its shuttle-flavored competitors. It also does the most complete job of preserving more of the STS workforce within the first few years after the orbiters retire.

The most startling aspect of the side-mount SDV presentation is the option to mount a crew capsule and escape system. Because the crew capsule would be located laterally to the external tank, most observers feel it would not be a great improvement over the shuttle when it comes to launch aborts. Precise guidance and thrust-vectoring would be required in the escape system to pull the capsule away from the ET, even if the abort was triggered while the ET was structurally intact. In a Challenger-like situation where the ET rapidly disintegrates, there may be little or no chance of protecting the capsule from ET-produced shrapnel.

Another abort scenario worth considering is the shuttle's Return to Launch Site maneuver. The shuttle stack would flip end-over-end and fire the engines in the opposite direction to cancel out the forward velocity and head home. The orbiter would then separate and glide in for a landing. On a side-mount crew launcher, the capsule doesn't have the same cross-range as the shuttle orbiter. Hopefully the escape tower would be able to pull it away from the stack and set it down somewhere in the Atlantic ocean for recovery. The bigger question is the point at which the escape tower is going to be jettisoned for a side-mount crew launcher. Will the service module engine have the thrust and steering necessary to pull free from the ET during late-boost aborts?

The side-mount SDV has been given extensive study since the days before the first shuttle launch, and it remains a valid approach for transporting large unmanned payloads to space. But is it suitable as a crew launcher? It's probably no less safe than the existing shuttle, but it would still give me a high pucker-factor if I was an astronaut. The cynic in me suspects that NASA doesn't take the side-mount crew launcher seriously, but is pitching it as a means of undermining the rationale for EELV or DIRECT. After all, DIRECT may be a more difficult and expensive development than a side-mount SDV, but it's much more suitable for manned aborts during all phases of flight.

The approach I favored during the early days of Project Constellation was a Delta IV crew launcher and side-mount SDV for unmanned cargo. It's the cheapest crew launcher paired with the cheapest heavy lifter design. I would not be surprised if the Augustine Commission seriously considers this combination.

Shuttle-Derived Fratricide

2009-06-12T21:23:00.000-07:00

Rocketman, in his uniquely-unforgettable style, is taking a look at the race to replace Ares I. He thinks the writing is on the wall for the current Ares I, but continues to hint at a return to the original "Shaft" from the ESAS report using a stock SRB and an air-start Space Shuttle Main Engine on stage 2. At the same time, he thinks that the proponents of Ares, DIRECT and Shuttle-C are taking aim at each other, with the taxpayers getting caught in the crossfire.

After reading the presentation on DIRECT 3.0 from the International Space Development Conference, I can't help but agree with Rocketman. I must first congratulate the DIRECT team for pulling out all the stops to present their concept as a more sensible alternative to NASA’s technically-challenged and budgetarily-bloated plans for Ares I & V. The presentation is incredibly slick, and it’s the best apples-to-apples comparison between the two plans to date.

But near the end of the slides is an unnecessary slap in the face of Shuttle-C, trying to fend off competition from the easiest shuttle-derived option of all. I find their arguments to be a bit of a strawman, because even the most ardent Shuttle-C supporters do not see Shuttle-C as a crew launcher (they often leave that task to EELV’s.) And there’s no reason that Shuttle-C couldn’t be adapted to the clean-pad concept that DIRECT touts for their vehicle.

I have to confess some sympathy towards Shuttle-C or a similar design (perhaps using stock RS-68's instead of SSME's.) It would be the cheapest shuttle-derived rocket of all, at least from a development budget standpoint. But it doesn't offer a lot of room for future evolution, and it inherits the same inefficiencies that are ingrained into any shuttle-derived rocket.

Is the re-opening of the launcher debate good for the taxpayers? To some point I'd agree, because Ares I is a very expensive and a very behind-schedule vehicle that offers little benefit over the Delta IV Heavy (which has already been paid for.) The debate we're expecting from the Augustine Commission is one which should have been taken to the public in 2005. But there's also the risk posed by getting mired in continual debate and wasting taxpayer dollars on a succession of aborted development projects like Shuttle II, X-33, Space Launch Initiative, and Orbital Space Plane.

For both Shuttle-C and DIRECT, time is not on their side. The infrastructure of the shuttle program, particularly at the Michoud plant where the ET's are built, is being dismanted as the blue-ribbon panels busily debate. Unless the dismantling is halted, the panel may be left with no other choice than to put its rubber-stamp on "Plan Griffin." I would still argue for Delta IV Heavy as the fastest, cheapest and lowest-risk method for getting Orion into space. To retain the shuttle workforce, LC-39 could be converted for EELV use. One pad would go to the Delta crew launcher, while the other would be reserved for a future EELV variant capable of 55-tonne payloads (as per the Northrop-Grumman Crew Exploration & Refinement study of 2004.)

The Augustine Commission absolutely has to get this right. NASA has lost a lot of credibility with its string of past failures in developing manned launch systems, and it's hard to see how the agency can sustain a manned spaceflight program after another embarassing cancellation. It's not too late to change ships and abandon Ares, but the successor system cannot afford to be cancelled during its development.

Hubble Disposal Revisited

2009-05-25T09:35:00.000-07:00

With the crew of shuttle Atlantis having completed the last servicing mission on the venerable space telescope, I've revisited the question of what happens to the large Hubble spacecraft when its mission finally ends in a few years. A piece of space debris the size of post-shutdown Hubble poses an increased risk to people on earth during an uncontrolled re-entry.

The original Hubble disposal plan called for a shuttle mission to retrieve it and send it back to earth. But the winding down of the shuttle program ensured that Hubble would out-last the spacecraft that delivered her to orbit in 1990. Besides, the risk to astronauts in order to deliver Hubble to a museum on earth really can't be justified for most people.

Back when Sean O'Keefe supported a robotic servicing mission to Hubble, the addition of a deorbit stage was considered. At least a deorbit motor would permit Hubble to control its re-entry and minimize the risk to people on the ground. The deorbit motor was also considered for the current mission before being dropped. Instead, the STS-125 astronauts added the Soft Capture Mechanism, which should allow future spacecraft to pay Hubble a visit. A deorbit stage could also be launched, although it would require some form of terminal propulsion and gudance to safely dock with Hubble.

It's always possible that a future Orion spacecraft could dock with Hubble, re-boost it, and perform maintenance. But Orion is ill-suited for the task at hand. It has no payload bay for delivering spare parts to Hubble, and there's no arm to reposition spacewalking astronauts who would repair Hubble.

The long-term Hubble situation reminds me much of the fate of Skylab. While the first American space station was boosted into a higher orbit in hopes that it would still be around when the Space Shuttle first flew, it ended up re-entering and breaking apart over the Australian outback two years before the first Space Shuttle mission. Hopefully NASA will have an executable plan to safely deorbit Hubble at the end of it's life, unlike Skylab. And if anybody's holding out hope for Orion giving Hubble another reprieve, I think they'll be sorely mistaken.

Amateurs talk rocket tactics, professionals talk rocket logistics

2009-05-19T21:28:00.000-07:00

The DIRECT rebuttal to NASA’s analysis of their concept includes some very telling observations of NASA’s mentality in creating and defending the existing infrastructure. Perhaps the most telling NASA observation comes on slide 64:

-More detail on Launch Infrastructure than on vehicle design.

--This is a design that is sized by infrastructure as they note in their paper.

--However to date Launch Infrastructure is not on the critical path of Ares-V or Ares-I

To which DIRECT responds by saying:

-The fact that the infrastructure is not being considered by Ares is one of the reasons why that architecture costs as much as it does.

--Cost of all supporting systems, not just infrastructure must be one of the many factors considered as part of the critical path.

All I can say in response is “Wow.” Are we to believe that ESAS was designed with little or no consideration of what the supporting infrastructure would cost? It would certainly explain why we’re stuck with the unaffordable Ares I and Ares V.

Further NASA statements such as “Ares I + Ares V uses 15 SRB segments, while two Jupiter 232’s use 16 segments” also reveal an incredibly simplistic approach to cost estimation. Such simple methods might be appropriate for pre-algebra students. Professional cost estimators ought to know better. That's why cost estimation is so difficult; there may literally be thousands of dependent and independent variables that make up the true cost of the system over its lifetime. Saving a few million in rocket hardware may have bigger reprocussions with development dollars, standing army costs, and infrastructure costs. It’s best summed up on Slide 26, where Jupiter’s higher launch costs (measured in tens of millions per launch) are offset by the savings of billions in development costs.

The DIRECT rebuttal also points out a problem the EELV advocates have encountered. In estimating upper stage masses, NASA has become excessively reliant on software tools like INTROS, which give fairly high estimates for upper stage dry masses. When INTROS cannot match the values for real, flight-proven hardware (like the EELV upper stages,) it might be time to revise the INTROS code. If nothing else, NASA’s impartial estimators should defer to the real values of flight hardware when the numbers conflict with the computer estimates.

All-in-all, DIRECT appears to be a more affordable architecture for a shuttle-derived lunar transportation system. I say this as somebody who earned a BS in Aerospace Engineering and actually did some serious study of solid-rocket internal ballistics during senior design class, giving me a first-order feel for how lengthy a new SRB development program will be for ATK and NASA.

With that being said, DIRECT still faces an uphill battle against “the unknown unknowns.” How well will the Centaur balloon-tank structure scale up to the larger diameter of the Jupiter rockets? What new guidance and rendezvous techniques and docking systems are required to mate the Earth Departure Stage to the Altair-Orion stack once on-orbit? What other previously-unknown problems, such as SRB heating of the core engines, will affect DIRECT once development begins?

At this point, a swap of Ares for DIRECT will result in little net gain from a schedule or technical risk perspective. While Ares proponents might argue that the last four years have seen the design mature, Ares is still years away from flying significant flightworthy hardware. The maturity of Ares today is comparable to where DIRECT’s predecessor, National Launch System (aka New Launch System) was in 1991. The only potential crew launcher with any maturity is Delta IV Heavy. If SpaceX is lucky, Falcon IX will have a successful flight before the Augustine Commission completes its report.

The Heat is On

2009-05-18T17:16:00.000-07:00

If you want some interesting technical reading, do yourself a favor and check out the DIRECT Launcher rebuttal to NASA's review of their concept. I'll go into depth about the review tomorrow, but the most exciting (or shocking, depending on your point of view) development comes on Slide 112 of the presentation:

DIRECT has come to the conclusion that the ablative nozzle of the RS-68A/B will not be sufficiently robust for a cluster application in such close proximity to the exhaust from a pair of SRB’s, and a regeneratively cooled nozzle is necessary to survive this extreme base heating environment.

The takeaway: RS-68 isn't going to cut it for DIRECT or for Ares V without some MAJOR modifications. The DIRECT team believes that a regen nozzle is necessary, and they're advocating the Space Shuttle Main Engine as a replacement. NASA is conducting a trade study between SSME and a regenerative RS-68 for Ares V. This is consistent with reports from earlier this year that SSME was back in the trade space.

We've been down this road before. During the days of ESAS, before the "Ares" name was official, there was Cargo Launch Vehicle (CaLV.) Much like the Jupiter 232 of DIRECT, it used Shuttle-derived tankage and an upper stage. It also used five SSME's on the core. Over the next year, the RS-68 replaced SSME because it would be too expensive to throw away five SSME's per flight. The consequence was a wider, all-new core with more propellant to compensate for the lower specific impulse of the less-efficient RS-68.

NASA faces the choice of switching back to SSME, or trying to create a regen RS-68. Both choices are fraught with many unknowns. How easy will it be to restart SSME production? Can any incremental changes to the SSME result in cost savings? After all, Wayne Hale has said that if the shuttle program continued past 2010, the next upgrade might have been a channel-wall nozzle to replace the thousands of welded coolant tubes in the current SSME nozzle. But a regen nozzle for RS-68 won't be trivial, and it will add to Ares V schedule and development costs. And if NASA is going to pay for a regen nozzle on RS-68, it should also reconsider the expansion ratio of the new nozzle to ensure an optimal balance between thrust level and specific impulse.

When I look at the design problem created by SRB heating of the core engines, I wonder whether "SSME vs. RS-68 Regen" is a false choice. For starters, could an ablative RS-68 be viable if the outer nozzle was thicker and absorbed more heat? For that matter, could RS-68 work if its position on the booster changed? Remember that on the shuttle, the main engines aren't mounted between the two SRB's. A similar arrangment could work on Ares V if the six engines were mounted in two separate pods. If the base of Ares looked like a clock with SRB's mounted at three and nine, one engine pod would mount at twelve and the second pod would attach at six.

Just when it might have seemed like the design of Ares V was set in stone, it's all open for debate again. Perhaps the sixty days of ESAS studies weren't enough to thoroughly review all of the underlying assumptions behind the study. At least the DIRECT guys deserve credit for laying all of their assumptions out in the open. Let's hope that NASA gets it right this time around.

My Military Acquisition Rant

2009-05-05T18:43:00.000-07:00

After a recent chat with a friend who is working on the F-22 program, I've decided that it's time for me to unleash my rant about the biggest problems I've observed with the way that the Pentagon and Congress deal with military acquisition. I make my case from the perspective that I hope we'll get smarter about the way we spend defense dollars, getting a good value for the taxpayer and ensuring that our fighting forces get the weapon systems that they need.

I think the poster-children for all the problems with military acquisition are the Seawolf-class and Virginia-class submarine programs. The Seawolf-class was designed during the 80's as a class of subs that could autonomously track and destroy Soviet ballistic missile subs. When the Soviet Union fell, the Seawolf-class was seen as a relic, and dropped after only three boats were authorized. But there was a problem; namely, how do you replace all the aging Los Angeles-class subs in the US Navy fleet? Rather than building more Seawolf-class boats, the Navy authorized the Virginia-class submarines. In comparison, the Virginia-class was smaller and slower than the Seawolf-class, with fewer torpedo tubes. After a lengthy and costly development program, the Virginia class proved to be only marginally cheaper per boat than the Seawolf-class.

Another case-in-point is the F-22 fighter program. I will be the first to admit that it would have been wise to cancel the F-22 back in 1992 when the Soviet Union dissolved. But that didn't happen, and the F-22 development program slogged on, logging its first flight in 1997 and Initial Operational Capability by late 2005. Now it appears that F-22 production will soon end at 187 airframes. While the F-22 is undoubtedly an expensive plane, much of that can be attributed to its protracted and expensive development. Now that the development costs have been sunk, the marginal cost of each F-22 is a steal compared to what the F-35 will cost early in its production run. By comparison, the F-22 is faster, stealthier, and more maneuverable than the F-35. Even the F-35's touted advantages in attack capabilities are largely moot, because the F-22 can also carry two Joint Direct Attack Munitions internally. The F-35's only advantage is the novel lift fan which allows the Marine Corps' variant to land vertically.

The F-35 Joint Strike Fighter is another example of a program that has pressed on in spite of its questionable value to the taxpayers. It's supposed to replace the Air Force F-16 and A-10, Navy F/A-18 (and the A-6 long-range strike plane, which has been retired for the last 12 years,) and Marine Corps AV-8 Harrier. But is it really necessary to build an all-new fighter possessing "an affordable degree of stealth"? Stealth is overrated after the enemy's air defenses have been wiped out, and it constrains how much ordinance you can carry. The F-16 and F/A-18 are still very capable airplanes, and will remain on-top with avionics upgrades and integration of the newest weapon systems. Even the venerable A-10 is becoming less relevant, with F-15E Strike Eagles performing much of the close air support work in Iraq and Afghanistan. While the Harrier brings some very unique capabilities to the battlefield with its ability to operate from short airstrips and amphibious assault ships, it's worth asking whether the costs of Harrier acquisition and operations were superior compared to using Marine AH-1 Cobra attack choppers to meet the mission requirements.

So the F-22 production will soon end, while troubled programs like Global Hawk are kept on life support. Global Hawk is five years behind schedule, while the Predator series of tactical unmanned aerial vehicles continues pressing on at a remarkable pace. Originally used for recon in the Balkans, the baseline Predator has become a vital weapon for taking out high-value terrorists in Afghanistan and Pakistan. The bigger Predator-B was re-christened as the "Reaper," and it's living up to its name in dishing out laser-guided death to Jihad Joe. The new Predator-C introduces stealth and higher speeds to the successful Predator formula. While Global Hawk is more of a strategic intelligence asset than the tactical Predator, its myriad delays have motivated the defense department to find interim solutions that get results.

The big lesson for Congress and the military acquisition bureaucracy is that major development programs may take a decade or more and will require billions of dollars. They should never be undertaken lightly. And once we commit to them, we have a duty to see them through to production and build as many weapon systems from that program as we can to meet our mission requirements. It is a complete waste of taxpayer dollars and a dangerous disservice to our fighting men and women if we go back to the drawing board every time that we balk at the unit cost of a major weapon system.

Orion Takes a Backseat to Nobody

2009-05-02T09:51:00.000-07:00

NASA recently announced that the Orion Spacecraft will be initially limited to a crew of four, even for ISS missions. This is another step backwards from the ESAS Study which called for a crew of six on ISS missions and four on lunar missions.

There is a very clear reason why ESAS had a requirement for six crew to the ISS on Orion. The ISS has a crew of six, and it makes sense for Orion to deliver a full crew compliment to ISS and return them to earth. The alternative, in the post-shuttle era, is to send two Soyuz capsules (or one Dragon, if SpaceX ever sees COTS-D funding.) Apparently NASA is counting on one Orion and one Soyuz being docked at ISS at all times. If the station had to be evacuated in an emergency, NASA will have to hope that both capsules work properly to get the full crew compliment home.

Officially, NASA is justifying the smaller crew because it will eliminate the need for two different seat configurations in Orion. Development costs and mass savings have nothing to do with it. Yet this argument is pretty weak when considering that Apollo supported three crew for lunar missions and five crew in the Skylab Rescue configuration. The difference between 1973 and today is that NASA was willing to seat its astronauts in two rows during the Apollo era. Orion is significantly bigger than Apollo, in part because NASA is unwilling to have astronauts sitting in two rows during a hard landing. Only time and testing will validate this safety fear.

With the growing likelihood that ISS will see a life extension to 2020 or beyond, it doesn't make a lot of sense to take seats out of Orion and prevent it from serving as an ISS lifeboat.

Test like you fly

2009-04-25T10:22:00.000-07:00

In the business of aerospace, the phrase "test as you fly" can never be repeated too often. All hardware should be tested on the ground in as realistic fashion as possible. Flight testing should come as close to the environments where the hardware will be flown. Traditionally, new rocket designs have been tested one stage at a time, using dummy upper stages. Why then would NASA reject this test strategy for Ares I?

Perhaps it's because Project Apollo abandoned incremental testing in favor of all-up testing. Nowhere was this more pronounced than Apollo 4, the first Saturn V flight, which was the first instance when the S-IC and S-II stages had ever flown before. Of course, NASA and its contractors had extensively tested the stages on the ground before, and S-IVB had been tested on Saturn IB launches. Project Apollo is often held up as a model for how a space program should be conducted, but it's really an exception rather than the rule. Apollo was the unique product of its circumstances, and its "crash the schedule" approach should not be viewed as standard industry practice.

The current Ares test schedule calls for Ares I-X this year, a test of a 4-segment SRB with a dummy fifth segment, dummy upper stage, and avionics that don't represent Ares flight avionics. The next step is Ares I-Y in 2012. I-Y will be the first flight of the real Ares I SRB, plus an inert upper stage that, minus the engine, resembles the real Ares I upper stage. Ares I-Y will also test the Orion escape system.

As I've said many times before, Ares I-X has little to no bearing on the Ares I flight hardware and should be terminated. Ares I-Y is a far better test because it does involve Ares flight hardware, but I'm not certain there's much to be gained from flying an engine-less second stage in place of a dummy upper stage.

Recently there's been talk of an "Ares I-X Prime" which would actually test a five-segment SRB with dummy upper stage. Now we're actually getting serious about "testing like we fly." This is what Ares I-X should have looked like all along. The problem with the "Prime" test flight, in my view, is that it's being considered as a replacement for Ares I-Y instead of Ares I-X.

At this point, Ares I-X doesn't really buy NASA anything, aside from positive PR if it works correctly. Ares I-Y isn't doing much more than Ares I-X Prime would do, aside from testing the supper stage structure under flight loads and allowing for the high-altitude abort test. A wiser and more fiscally-responsible strategy would be cancelling both Ares I-X and Ares I-Y, skipping ahead to Ares I-X Prime, and then making Orion 1 (the first in-flight ignition of the upper strage and first on-orbit test of the Orion spacecraft) the last test flight before humans fly on Ares-Orion.

Spiral Development: The Chair Force Engineer Plan for Closing the Gap and Enabling Human Lunar Exploration

2009-04-21T21:36:00.000-07:00

Today's big news for Project Constellation comes in the form of Aerospace Corporation's independent study of using Heavy EELV's to launch the Orion spacecraft. The short of it: there are no problems with black zones, and the launchers can launch Orion with performance to spare. But the costs of doing so won't be trivial, and EELV+Orion won't be operational until 2014 or later. That's not much of an improvement over Ares I.

Right now NASA faces two challenges that are often opposed to each other. The first is fielding a human space launch capability in a minimal amount of time after the shuttle is retired. The second is the political consideration of retaining as many shuttle jobs as possible after the shuttle retires. Ares retains shuttle jobs, but it won't be ready for another six years or more. EELV and COTS-D might be able to shorten the post-shuttle gap, but they don't retain the shuttle workforce.

Since everybody seems to have their own ideas about how Project Constellation should run, I'd like to share mine. My ground rules are simple:
1) Get a manned spacecraft flying to ISS as soon as possible
2) Whenever possible, minimize development costs
3) Take a spiral approach to development, sacrificing the arbitraty 2020 moon landing date in favor of incremental and affordable advancements.

The first step would be halting all work on the Ares launch systems to evaluate which elements are applicable to the spiral development program that I propose, albeit on a longer time schedule than the current NASA plan. Once that's been accomplished, the Chair Force Engineer plan for manned spaceflight can begin in earnest.

1) Fully fund SpaceX's COTS-D effort
This is a no-brainer. Dragon is a simple capsule designed for one mission: deliver humans and cargo to ISS. It's the furthest system along the path that can shorten the gap.

2) Replace the current Space Shuttle system with a block I Shuttle C
Shuttle C shouldn't be hard to develop, as much of the work was completed prior to 1993. Even the leftover engines from the shuttle program can be expended on Shuttle C missions. While Shuttle C would be tasked with delivering cargo to ISS, we have to face reality: it's really there as an interim measure for retaining the shuttle workforce over the long haul while not endangering astronauts on further shuttle missions.

3) Make block upgrades to Shuttle C as the budget permits
The first order of the day is to find a replacement for the finite supply of space shuttle engines. RS-68 is a good canddiate, but it needs upgrades to even come close to SSME performance levels. The new injector plate and turbopumps from RS-68A&B are a good start, but a regeneratively-cooled nozzle would be really nice.

Shuttle C is also expandable in the SRB department. If NASA insists on paying ATK to develop longer SRB's than the current ones used byu the shuttle, they can be integrated with Shuttle C fairly easily.

4) Create a manned capsule capable of returning to earth from lunar trajectories
Perhaps Dragon could be upgraded for lunar missions. Certainly SpaceX has been discussing circumlunar Dragon missions, and I wouldn't rule out a "Block 2" variant with a beefier heat shield and enough consumables for a lunar mission. If Dragon Block 2 doesn't pan out, the Orion spacecraft could be revived using Falcon 9 Heavy or a Heavy EELV as a launcher.

5) Create an Altair lander and other elements of a lunar transit system, designed for launch on Shuttle C.
I'm agnostic on whether rendezvous in earth orbit is superior to rendezvous at an earth-moon Lagrange point. The important thing about my plan is that decisions such as EML vs. LEO are deferred until the budget exists to develop lunar-capable hardware. Certainly both would be possible using Shuttle C, in-space assembly, and on-orbit refueling. It's certain that a competent lunar mission could be staged using a capsule launched on a Heavy EELV, a lander and propulsion stage that are launched unfueled by a Shuttle C, and a load of propellant delivered by a second Shuttle C.

In closing, NASA has gotten itself into a lot of trouble by avoiding the "pay as you go" approach in favor of redoing Apollo on a shuttle-era budget. Unless the agency changes direction very soon, there will be a long gap and a brain drain in central Florida. The solution is the time-honored technique of spiral development. NASA should accelerate Dragon, fly an interim Shuttle C, and upgrade Shuttle C for sustainable operations before devloping lunar hardware in earnest. Such an approach gives policymakers enough options to ensure that the US stays in the manned spaceflight business even if the lunar goal is abandoned or replaced with more ambitious exploration targets.

Shaky Math

2009-04-20T22:17:00.000-07:00

SpaceX is delaying its next Falcon 1 launch because of "dynamic interactions" between the launcher and its RazakSat payload. A lot of commenters are coming down hard on SpaceX or wondering how this issue could have been left to simmer until the very last minute. Having observed a spaceflight program dealing with serious launch vibration issues, it's pretty easy for me to see how this happened.

Every launch vehicle users' manual contains a vibration profile for the launcher across the range of frequencies at which the rocket is expected to vibrate. SpaceX has been publishing users' guides since at least 2005, three years before the vehicle made its first successful flight. Furthermore, the flight configuration is somewhat different from the original one in the first users guides, after the change from a Merlin 1 to a Merlin 1C engine on the first stage.

The most likely scenario is that RazakSat was designed to the old vibe specs that were published for Falcon 1 several years ago (after all, RazakSat wasn't designed, fabricated, and integrated overnight.) It wasn't until all the data came back from the successful September 2008 Falcon launch that the vibe problem was discovered with RazakSat. Perhaps it affected certain structural modes of RazakSat, or maybe the vibe profile was more intense across the spectrum. Either way, it's time to go back to the drawing board.

The vibe problem doesn't require any drastic solutions. By placing a series of Softride isolators between the launcher and the payload separation system, vibrations can be damped down to a survivable level. A coupled loads analysis is absolutely necessary to examine the full launcher-softride-payload stack and determine how the isolators can be tuned for the RazakSat mission. I don't know how much time CSA Engineering would need to solve the RazakSat issue, but it would seem like the quickest possible option for getting the next Falcon 1 successfully off the pad.

Silent Eagle

2009-03-18T21:09:00.000-07:00

Boeing recently unveiled its concept for the “Silent Eagle,” the next model in the F-15 family designed to keep the venerable super-fighter in production for a few years more. In the Silent Eagle design, Boeing is hoping to offer foreign air forces an “affordable” degree of stealth. While the specifics are highly classified, the basic concepts behind designing a stealth aircraft aren’t hard to grasp:

--Introduce as few protuberances or angles as possible in the overall layout.

--Utilize radar-absorbing materials in the aircraft’s structure

--Submerge the engines in a way that protects the compressors from exposure to radar

--Reduce the noise and infra-red signatures produced by the engines through cooling, shielding the nozzles, sound dampening, and other methods.

The F-15 is still a world-class fighter aircraft, especially in the hands of a highly-trained pilot. Continuous avionics upgrades could keep it competitive with super-fighters like the F-22. But the F-22’s distinct advantage is that the airframe was designed to be stealthy from the start. While Boeing has done a few things to the F-15 airframe to reduce its radar return (submerged weapons carriage, an exportable radar-absorbent material coating on the airframe, and outward-canted fins,) it’s still a decidedly non-stealthy airplane.

Friendly foreign air forces have to face the question of whether they need stealthy combat aircraft in their arsenals. In scenarios like Afghanistan and the 2003 invasion of Iraq, stealth was not as vital a factor as it was in Operation Desert Storm because of the enemy’s degraded air defenses. Stealth often becomes a hindrance because internal weapons carriage reduces the overall payload the aircraft can carry.

I’m interested to see if anybody is interested in buying the F-15 “Silent Eagle,” especially with the price of the F-35 rising. The F-35 was designed with an “affordable” degree of stealth in mind, but it’s quickly becoming as expensive as the F-22 (an airplane which is faster, stealthier, more maneuverable, and just a better all-around air-to-air fighter aircraft.) "Silent Eagle" is the poor man's F-35, sacrificing the F-35's level of stealthiness for affordability, superior maneuverability, a higher top speed, a dual crew, and twin-engine reliability.

Japan is likely to be the target of Boeing's "Silent Eagle" marketing. The Japanese already fly F-15's but really want the F-22. With the US Congress prohibiting F-22 exports, Japan will likely settle for the F-35 unless Boeing can make a better offer (i.e., one that includes a higher degree of the plane's production in Japan) with the "Silent Eagle."

A Jem of an administrator?

2009-03-18T19:31:00.000-07:00

The hunt for a NASA administratorgot even messier today, with the nomination of retired Major General Scott Gration to the position of envoy to Sudan. Formerly the rumored front-runner for the job, his position has been taken by astronaut Mae Jemison in the rumor mill's pool of candidates.

I take the Jemison rumor with more than a grain of salt. My personal preference is still for Lester Lyles or Steve Isakowitz, of the people whose names have been floated. But with that being said, I'm interested in the Jemison rumors because I've actually met Dr. Jemison during a lecture and a Q&A session. I came away highly impressed with her intellect, but she definitely struck me as a scientist moreso than a manager or a leader. Maybe it was just the subject of her lecture which blinds me to the possibility of her as an administrator, but she strikes me as somebody who takes a very global view of utilizing human technological prowess to solve social problems and alleviate human suffering. These goals are very admirable, but they're not completely aligned with the NASA mission.

Service as an astronaut does not qualify one to be NASA administrator. At best, it should be viewed neutrally for an administrator candidate. Management acumen is the key here, and that's the reason why I view General Lyles or Steve Isakowitz so highly compared to the other rumored candidates. That might not mean the others are bad managers, it's just that they haven't had the opportunities to demonstrate it on a large scale. With the agency in a precarious position, I'd like to see a proven track record before supporting a candidate.