Thread

NASA asked several former SR-71A staffers to help secret restart

327 points · 403 comments · ilamont

ggm · 1790747290 · focus · HN ↗
A couple of questions/observations:
1) when people say "destroyed the jigs, tools and spares in 2007" What do they actually mean? Burying things isn't destroying. Putting them in a furnace is destroying. Is it possible that both parts, and tools actually are recoverable e.g. from the seabed? The dimensional stability might be off, but to help reconstruct tools, it's not nothing. Likewise digging up something buried in its packing crate is not rocket science.
2) "that would be ludicrously expensive" doesn't mean much any more. It's not unlike "we can't make a saturn 1 any more because the tools were destroyed and it would be ludicrously expensive to make an F1 engine" -well yes, but thats not impossible, it's just unlikely and expensive. So maybe this is unlikely, expensive but ... has a unicorn sugar daddy?
3) there are craft in all sorts of places. Not just on sticks outside NASA property. I am not a historian or a federal government employee, but I wouldn't think it impossible for people to ask other agencies to let you inside the shell and remove the bits you want, or even ask for it back. The one on a stick in Balboa Park San Diego might have associated boxes of bits-and-bobs..
4) its a titanium alloy. It's temperature and corrosion resistant, noting some things (like chlorine according to the web) are bad for it. It's not made of pure chinesium or balsa wood. Interior surfaces would be in pretty good shape.
1. djriley · 1790752910 · focus · HN ↗
  As far as number one goes, the tooling has almost certainly been recycled when they say "destroyed". By recycled I mean in to new steel in an electric arc furnace. It's pretty common even in every day mass production for tooling to either be sent for destructive testing or a destructive decomissioning/EOL use (cutting, defacing, used for practice for facility apprenticeship, etc). I imagine something on the level of Blackbird tooling would have gone through a very strict decomissioning process before it even hit the scrap bin.
  As far as #2 and the rest goes, I agree that with enough money you could make anything happen. However, sometimes recreating something so complex could be a "not enough money in the world" type situation. Sure, drawings and specs exist, but even on today's 3-d modelled assembly you're not typically modelling every single part to full accuracy. You have things that are off the shelf that might be a black box drop in, you have things you contract out that are built to spec. You know what you get, but not necessarily exactly how it's done. Then in your own facility there is a certain level of institutional knowledge that is not necessarily documented in such a way you can just recreate it.
  Finally, one of the biggest hurdles, there's are not things that you can just throw an LLM and some engineers at. The actual trades themselves have changed so much since the time of production your only option is to call in retirees. The machinery is different now and so are the workers.
  I feel like with a large budget they could definitely get an SR-71 in the air for testing and exhibition purposes, Id love to see it happen. I guess it really depends on how much was removed and destroyed when the machine was decomissioned and how much damage lack of maintenance, environmental factors and age have taken their toll. The good news is it hasn't been operated in a long long time. The bad news is it hasn't been operated in a long long time.
  Source: I am a toolroom machinist at a material science lab in the aerospace and defense sector.
  1. bluGill · 1790772957 · focus · HN ↗
    Large production runs (think cars) the tooling is sold to a third party to make spare parts. However that third party will watch what sells and scrape the tooling when sales are not large enough to justify keeping it around. Things that never break have the tooling scrapped early. Things that collectors break the tooling stays around - if it wears out they make replacement tooling.
    The SR-71 was not made in large enough numbers to get the above treatment. If the government wants spare parts they need to pay to keep that tooling around.
  2. Tangurena2 · 1790791755 · focus · HN ↗
    > I imagine something on the level of Blackbird tooling would have gone through a very strict decommissioning process before it even hit the scrap bin.
    Being a military vehicle, the tooling would have been classified. It would need to be "demilled" (or de-militarized) before disposal. Depending on the materials involved, it could be melted or shredded before burial in a classified landfill.
2. hvb2 · 1790758982 · focus · HN ↗
  > The one on a stick in Balboa Park San Diego might have associated boxes of bits-and-bobs.
  That's an A-12, not an SR-71
3. crote · 1790759658 · focus · HN ↗
  > we can't make a saturn 1 any more because the tools were destroyed and it would be ludicrously expensive to make an F1 engine
  The bigger problem there is that we don't have the people any more.
  The Rocketdyne F1 was the pinnacle of hand-crafted engineering, with each engine being slightly different and the people having to account for those differences during assembly. It has a whole bunch of complicated welds which require a lot of tweaking, adjusting, and literally days of welding work? Neil's got to go to the moon, so you better get to it!
  Those highly-skilled highly-specialized engineers don't exist any more, and for a good reason: with CNC and robots we can achieve far superior results for a fraction of the cost. It just requires the designers to make it automation-friendly from the start. Those skilled people retired (and by now died) without a replacement, because the job had become obsolete.
  So no, we literally cannot build a new Rocketdyne F1. We can design and build a better F1-like engine, though!
  1. throwawayffffas · 1790760566 · focus · HN ↗
    > with CNC and robots we can achieve far superior results for a fraction of the cost
    As far as I know that is still not true. Manual welding provides less defects and higher quality welds. Provided one has experienced welders. The cost is much lower for robotic welding but the results are still not as good as manual welding.
    > Those skilled people retired (and by now died) without a replacement, because the job had become obsolete.
    The skills can be acquired by new people.
    Regardless I believe the industry has moved to 3d printed parts for engines due to lower costs, higher throughput. And in either case rigorous inspections are the way to get reliable parts.
    I do agree that they cannot build a new F1, but they can build a new better model. But I believe that has to do with engineering and the loss of the contextual knowledge and experience building these things, the loss of why the design settled at what it did, why the processes settled to the ones documented, the undocumented knowledge the people building these had.
    This knowledge can be rediscovered, but it would be easier/cheaper to start with a new design and acquire that knowledge organically.
    bluGill · 1790772630 · focus · HN ↗
    > The skills can be acquired by new people.
    They can be. However it will be expensive to train them. (starting with figuring out what training is needed - probably a lot of trial an error because not all of this was written down) Also you will need to pay people to get this training - they won't pay for it themselves since it is unlikely to be a useful job anywhere else anymore so they have better investments in their time/money.
    Tangurena2 · 1790791393 · focus · HN ↗
    > The skills can be acquired by new people.
    I remember a Wall Street Journal article about 25 years ago where business leaders were upset that there was a "terrible" shortage of Swiss-style machinists in the US (whose daily output of tiny stuff would fit into a shot glass). And that they had to import those machinists from Germany.
    Buried in the lede was that to get the skill level needed requires an apprenticeship that took at least 10 years. Germany provided that with trade schools and subsidies for hiring apprentices. In the US, the Cold War provided the money and incentive for aerospace and defense companies to subsidize that apprenticeship. High schools used to supply much of that trade education. I remember the high school that I was going to attend in NJ had vocational programs (for boys) in vending machine repair, machine shop and auto repair. Vocational education moved from high schools to community colleges. Along the way, community colleges went from free (for students) to something students have to pay for.
    So the question becomes "who is going to pay for this?" I don't believe that what would be needed can possibly be done in America.
    lovich · 1790799075 · focus · HN ↗
    US corporations are allergic to paying for training in any form.
    Everytime it’s come up people always argue that if you train the employee they’ll just leave for more money once they’re skilled.
    Somehow just paying them the market rate so they stay, or even making a (shudders) contract with the employee to stay for X number of years in exchange for the training costs is never an option.
    They’d rather have the position stay empty or outsource outside the country even if that has associated issues with shipping costs or quality control.
    MentalM · 1790801812 · focus · HN ↗
    > Somehow just paying them the market rate so they stay
    But your competitors can pay them more anyway, because they have not spend their money on training.
    > a (shudders) contract with the employee to stay for X number of years
    Literally shudders. Employer has no practical way to ensure adequate quality of work from their employee. Generally it is not a problem, because employer can get rid of those workers one way or another, but when you have spent money upfront... Shudders.
    lovich · 1790803143 · focus · HN ↗
    Thank you for reinforcing my point that no US corporation wants to pay for training.
    > But your competitors can pay them more anyway, because they have not spend their money on training.
    No, they spent their time without even having a partially trained employee and just having empty positions. If they are still outcompeting you, access to labor wasn’t your problem.
    You can structure a contract so that the company has the right to fire for performance still. It’s how moving bonuses are normally done with a “you’ll work here for X year/s or return the bonus”
  2. Beretta_Vexee · 1790761728 · focus · HN ↗
    > with CNC and robots we can achieve far superior results for a fraction of the cost.
    This is only true for mass production, where the set-up costs are spread across thousands of units. For small batches, the cost of automation often exceeds the cost of the batch itself. CNC machines are not magic; they require qualified and competent staff.
    The same applies to quality control, fitting and assembly.
    I don’t think they’re planning to start mass producing of SR-71s.
    > because the job had become obsolete
    You are greatly underestimating the number of parts, welds and inspections carried out on critical equipment that are done by hand or in small batches by highly skilled workers. The fact that they use a CNC machine does not make their job obsolete. In fact, quite the opposite is true, its require more skills.
    Apart from the turbine section, virtually nothing on a helicopter is produced with a high level of automation or in large batch.
    m4rtink · 1790768670 · focus · HN ↗
    Still, I don't think anyone is ever going to hand assemble thousands of tubes for nozzle cooling & prepare them for brazing.
    Not when you can get the same for a fraction of the cost by CNC milling the channels & then shrinking a jacket over it. Or in some cases even 3D printing the thing.
    fragmede · 1790772964 · focus · HN ↗
    How does SpaceX's 3D printed raptor engine factor into your analysis?
    verzali · 1790780808 · focus · HN ↗
    The one that keeps failing?
    [deleted] · 1790780932 · focus · HN ↗
    [deleted]
    fragmede · 1790781222 · focus · HN ↗
    Does it? SpaceX doesn't publish official numbers, but nextspaceflight.com has the Falcon 9 at 99.5% success rate, which seems a bit better than "keeps failing" to me.
    <a href="https://nextspaceflight.com/rockets/3/" rel="nofollow">https://nextspaceflight.com/rockets/3/
    efromvt · 1790785413 · focus · HN ↗
    I actually agree with your point overall, but Falcon 9 uses the Merlin, not the newer raptor 3 for starship which is more 3d printing and has had some teething issues (no definite causation, and I expect they’ll get it sorted).
    verzali · 1790789816 · focus · HN ↗
    Falcon 9's don't fly raptors
    AshleyGrant · 1790793482 · focus · HN ↗
    The Raptor v3 had a 7% (3/39) failure rate on yesterday's Starship Flight 14. As others have mentioned, Falcon 9 uses the Merlin engine, which is a completely different, much lower complexity engine.
    Beretta_Vexee · 1790774344 · focus · HN ↗
    The assembly of the tube bundle in a nuclear steam generator is still carried out mainly by hand, using hundreds of shims, anti-vibration bars and supports.
    At the other end of the spectrum are stamped-plate heat exchangers, which are mass-produced using a press line.
    Each has its own specific application, and they are neither comparable nor interchangeable. The comparison makes no sense.
    rkangel · 1790773755 · focus · HN ↗
    >> with CNC and robots we can achieve far superior results for a fraction of the cost.
    > This is only true for mass production, where the set-up costs are spread across thousands of units. For small batches, the cost of automation often exceeds the cost of the batch itself. CNC machines are not magic; they require qualified and competent staff.
    This isn't right.
    CNC machines aren't magic and they do require skilled people to design for them and operate them.
    BUT: they are an enormous advance on capability compared to 30 years ago and are absolutely not limited to mass production. 3D CNC milling is how most prototyping of metal parts is done and can be done to extraordinary precision, repeatably. It was always a low volume technology - it was Apple that started applying it in volume as part of mass manufacture.
    BoxOfRain · 1790786407 · focus · HN ↗
    While not metalwork, some are surprised to learn how old CNC machined guitars are. I have a Peavey T-60 and they were among the first CNC-machined production guitars in the late 1970s. It's going strong to this day as well, they're very well-built instruments.
  3. dghughes · 1790774477 · focus · HN ↗
    > The bigger problem there is that we don't have the people any more.
    You don't have the education system and work ethic, stable family, curiosity. Many young people feel college is a waste and YouTube or AI has all the answers. Children in schools even now in 2026 right up to high school and even college can't read. Many who can read can't comprehend what they are reading.
    In addition to that I recall a UK study that said smartphones have caused a lack of hand dexterity. Not social media or content but the phone itself a two dimensional surface means hand dexterity is not developed. People do not have hobbies like wood working, sewing, anything that involves fine manipulation and strength. The biggest hit is to the medical field and lack of surgeons because people in medical school now do not have fine motor skills needed for the job.
    rtkwe · 1790776620 · focus · HN ↗
    > You don't have the education system and work ethic, stable family, curiosity. Many young people feel college is a waste
    I think a lot of this has been driven by businesses completely dropping their part of the deal in a pursuit of ever increasing profits. Formerly there was the long term promise that staying with one company would be rewarded and instead now for 99% of companies you're deeply punished if you don't hop jobs every couple years for a pay bump. Then they've also lobbied to completely gut funding for education to lower taxes or shift into subsidies. And a lot believe college is a waste because there's been a huge reduction in the value of just holding a college degree while the costs have ballooned.
    The whole system that created it has been dismantled for profit long before the culture of it started to fall apart.
    tclancy · 1790813637 · focus · HN ↗
    I’d suggest questioning the sources you are reading. Wood working and sewing are hugely popular hobbies across younger generations. There used to be a site, Ravelery.com maybe, that was on here all the time because of their engineering blog and all the work involved in sharing sewing patterns.
  4. nosequel · 1790778186 · focus · HN ↗
    Just to clarify one thing, Edwards AFB still has a lot of those highly-skilled engineers. Edwards has a huge machine shop with all the fancy tools and the engineers in there job is mostly making one-off replacement parts for planes. NASA and the Air Force are still flying all sorts of test planes out there and they often need some part they can no longer get from the manufacturer. They drop the spec for the part and it gets made, sometimes it takes a long time, but I promise there are skilled people on that base who can make it.
    IMHO the SR-71 is going to be problematic due to sourcing the materials and fluids more than finding skilled CNC techs.
    source: worked on Edwards for several years
    jjuel · 1790780746 · focus · HN ↗
    No doubt there are highly skilled engineers there, but saying "those" might be a stretch. It is possible someone there has worked on an SR-71A, but it last flew 27 years ago. It was originally introduced 60 years ago. A lot of the knowledge about this plane has most likely unfortunately passed on. That isn't to say people can't learn, but it is a tougher starting point. Honestly, almost like starting over I would guess.
    Jtsummers · 1790791258 · focus · HN ↗
    USAF has a lot of TOs (technical orders) that include things like schematics for the aircraft and its components. I'd be surprised if that data has disappeared or was incomplete for the SR-71. IME, TOs have been getting worse and systems from the time of the SR-71's period of service were generally better documented, though not perfectly.
4. Beretta_Vexee · 1790761238 · focus · HN ↗
  So titanium alloys are not completely resistant to all forms of corrosion. They are particularly prone to galvanic corrosion, which means that specific tools must be used, all forms of ferritic contamination must be avoided, special tools must be used, and they must be stored separately, etc.
  This is very labour-intensive, which is why it is generally carried out in dedicated workshops, with specialised equipment, and so on, by staff who have been specifically trained and do nothing else.
  If you add jigs, production-specific tools, and so on, all of that has been lost and needs to be recreated: staff need to be trained, QA defined and workshops need to be reorganised. This can take decades to return to the expected standard. You can throw as much money at this sort of problem as you like without actually being able to speed things up.
  Finding the drawings and dimensions is the easy part of reverse engineering a mechanical device. The real challenges lie in identifying the manufacturing processes and quality control procedures, and achieving the expected performance with an acceptable scrap rate.
  If I place a monocrystalline turbine blade on your desk, you’d be able to draw up the plans for it. But that would tell you absolutely nothing about the processes required to produce a monocrystalline ingot of a nickel superalloy.
  Source: former mechanical engineer in the nuclear industry, managing obsolescence was one of my day-to-day tasks.
  1. PostOnce · 1790772954 · focus · HN ↗
    "decades" is a stretch.
    The original A-12 took 4 years (or less) to design and build from scratch with slide rules and manual machine tools.
    Surely we can match that with our 70 years of advanced knowledge and equipment?
    Maybe our risk tolerance is low now, and we don't have Kelly Johnson.
    brookst · 1790773918 · focus · HN ↗
    Risk tolerance perhaps? But also our increased capabilities make it harder to keep things simple. Should it be radar-opaque? Of course! Capable of autonomous flight? Duh! Carrier landings? Well sure, that might be needed. Refuel midair? Obviously. Sigint to the gills? Seems useful…
    mitthrowaway2 · 1790781897 · focus · HN ↗
    The original definitely could refuel midair.
    brookst · 1790949374 · focus · HN ↗
    Sure, my point was more that the original was carefully optimized, today it’s easier to just check all of the boxes.
    j4k0bfr · 1790774108 · focus · HN ↗
    Not a mechanical engineer here, but I reckon close to a decade would be pretty realistic for full operational restoration. Even a small amount of lost critical maintenance knowledge could cost the whole airframe.
    I'd compare it to a really old codebase. Sure, our modern tech is much better. But if you need to make an old, top-secret COBOL program work as-is, you're in a pickle. Sure, we could rewrite it in Rust and make it way better, but management sees it as more cost-effective to just "turn the old one back on, it worked great!". And unlike software, it's pretty hard to comprehensively test a plane in a non-destructive way. Bolt falls off turbine while in flight, etc etc. Losing even a single SR-71A airframe would be a massive headache, methinks.
    MisterMower · 1790776559 · focus · HN ↗
    “I’d compare it to a really old codebase.”
    Yes, you are not a mechanical engineer.
    j4k0bfr · 1790838933 · focus · HN ↗
    What, it's a good analogy for this audience. I know enough to have an opinion though. You'll never see me using a thread to locate a part. And I know taste isn't the only difference between red and blue loctite!
    If you think my reply was off-base, give me a bit more than this mate.
    Beretta_Vexee · 1790775100 · focus · HN ↗
    The A-12 was not developed from scratch, whether in terms of its design, production facilities or in-house expertise.
    Design is a very different matter when you have a workshop full of skilled workers and machinery right on your doorstep, who can critique your work and explain what they can and cannot produce. A lot of engineers discovered this the hard way when companies started outsourcing to the other side of the world and lost control of production process.
    Designing parts that look nice but are impossible to machine or assemble is simple.
    Designing the plane may only have taken four years, but training the staff, organising the workshops and mastering the production tools took much longer.
    Just look at the struggles faced by all the organisations that stopped producing anything for a long time and then wanted to restart production. Whether it’s ships, aeroplanes or nuclear power stations, each time it takes something close to ten years to restart.
    When they manage to do so.
    dingaling · 1790775735 · focus · HN ↗
    "Designing the plane may only have taken four years, but training the staff, organising the workshops and mastering the production tools took much longer."
    Lockheed had no experience with titanium prior to OXCART. 95% of the first 6,000 sheets of titanium had to be scrapped.
    It was the first production design to incorporate low-observable shaping.
    It was 50% faster than anything Lockheed had previously tried to build, and four times faster than the U-2.
    And they literally did all that between April 1958 and April 1962.
    So, yes, it was designed from scratch as nothing useful from prior projects read across to it.
    mmooss · 1790775214 · focus · HN ↗
    Complexity and knowledge grow over time. It's likely that the last SR-71 and the processes and materials behind it were much more complex than the first. You have to recreate not only the first unit, but decades of added knowledge, skill, and complexity.
    Merad · 1790778805 · focus · HN ↗
    The A-12 was built in an era when the aerospace industry was flush with knowledge and active R&D into mach 3+ flight - everyone was convinced that it was the future. Today's industry is heavily optimized for subsonic airliners and fighter jets that have top speeds of "only" mach 1.5-2. No one in the west has built a mach 3 aircraft since the 60s and not in Russia since the early 80s. The knowledge isn't _lost_ (well, we hope) but there is a lot that will need to be relearned, and we all know how even the best documentation is usually missing a lot of details.
    HumblyTossed · 1790791486 · focus · HN ↗
    > Surely we can match that with our 70 years of advanced knowledge and equipment? I don't think we can, because: > ... we don't have Kelly Johnson.
    or the engineers from that time who had an intuitive knowledge of how this should all be designed. You can't teach a computer intuition.
  2. toomuchtodo · 1790776854 · focus · HN ↗
    What are your thoughts on creating processes and systems to maintain continuity of this institutional knowledge across programs and talent generations? How do you keep this muscle memory strong over decades besides keeping folks building and working? Or would you say that is the only way?
  3. Tangurena2 · 1790790410 · focus · HN ↗
    > They are particularly prone to galvanic corrosion, which means that specific tools must be used, all forms of ferritic contamination must be avoided, special tools must be used, and they must be stored separately, etc.
    The C4 Corvette had a titanium component back in the early 1980s (I worked for GM back then). The piece was flat and mechanics tended to use it to hold tools. Leaving the tool on that piece when closing the hood resulted in a dented (fiberglass) hood. Most tools (at least back then) have a cadmium coating (to keep them shiny). Cadmium causes corrosion to titanium. There were lots of service bulletins about this.
    gurumeditations · 1790792045 · focus · HN ↗
    Do you mean the magnesium pizza box?
5. lp92 · 1790771418 · focus · HN ↗
  If I recall correctly while reading Ben Rich's book he said the tooling was cut up in to pieces and sold for scrap metal.
6. nancyminusone · 1790772943 · focus · HN ↗
  Sure you "can" have a new F1. But you could also make a brand new design using current capacity manufacturing that will also do the job for a lot less. So why would you do the former?.
7. Tangurena2 · 1790790654 · focus · HN ↗
  The original tooling to build the aircraft were destroyed back in 1968.
  <a href="https://news.ycombinator.com/item?id=8251084">https://news.ycombinator.com/item?id=8251084

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