[austinl]

I’d recommend reading Skunk Works by Ben R. Rich for more on the engineering of the Blackbird and other special aviation projects.

I knew the Blackbird was fast, but didn’t quite realize how fast until reading this book. The SR-72 would cruise at Mach 3, or three times the speed of sound. It would do this at 80,000 feet, over twice the traditional cruising altitude of a 747. Even at this height, where the temperature is -60°F, friction would cause the fuselage to heat to 600°F. This would melt traditional aircraft, so the plane was built with titanium (ironically supplied by the Soviet Union). The Blackbird used to overfly North Korea five days a week in just ten minutes.

[nehal3m]

According to this [0] article it leaks fuel sitting on the runway because:

"The fuel system of the SR-71 could not be sealed permanently because there simply were no sealants that were flexible and durable enough to deal with those kind of temperatures and shrinking-expansion cycles."

I think that says enough about how bonkers fast that thing is.

[0] https://nodum.org/was-sr-71-blackbird-leaking-fuel/

[SkyMarshal]

Yeah, heat expansion made it airtight at Mach 3, but sitting on a runway with its parts contracted back to normal dimensions, it had leaks.

[GartzenDeHaes]

Not just on the runway. The hangers had big drains in them to catch the fuel and anyone unfortunate enough to have to work under the plane would get soaked. "Hey, I think the plane is leaking" -- me.

[Loughla]

What blows my mind is that this aircraft was originally shown, formally, in 1964.

1.9.6.4.

They had this level of engineering in 1964.

Just imagine what shit goes on behind closed doors today. It really does sort of stagger you.

[game_the0ry]

Given how bloated and wasteful our government is today, and how much the dept of defense blew on the F-35, I would be staggered if anything useful happens behind closed doors, besides corruption.

I think we were able to accomplish a lot more in the past.

[bragr]

>Given how bloated and wasteful our government is today, and how much the dept of defense blew on the F-35

You are listening to the fighter plane mafia too much. F-35 is a capable platform with a reasonable but large price tag for those capabilities. If you want to have a discussion of those capabilities, and whether those are needed, that's fine, but "big price tag == corruption" isn't a self supporting argument.

[m348e912]

>>F-35 is a capable platform with a reasonable but large price tag for those capabilities.

We might have a different understanding of what reasonable actually means. I am curious if you are willing to share your understanding of how much has been spent to-date on the the F-35 program and your thoughts on how that price tag may be considered reasonable for what was delivered. I'm not being combative, I am genuinely curious.

[__MatrixMan__]

The majority of the engineers where I live work for, or have worked for, defense contractors. I've shut down a defense contractor recruiter once a week or more for the last several months. It's insanity.

I've been a fly on the wall for so many conversations about the stuff they're accustomed to spending money on... Fighter plane mafia aside, I have no trouble believing that that money is going nowhere useful.

[game_the0ry]

> "big price tag == corruption"

The DoD has failed 5 audits in a row. Take that however you want.

[nradov]

The DoD has had screwed up accounting systems for decades because Congress never appropriated funding to fix them. When the audits started a few years ago there was no expectation that they would pass. The goal is to identify the problems so that they can gradually be fixed without disrupting ongoing operations.

[Loughla]

Is your argument that DoD fails audits because they don't have enough money?

[game_the0ry]

See: https://en.wikipedia.org/wiki/Iraq_for_Sale:_The_War_Profite...

Stop coping.

[oatmeal1]

F-35 is an awful, awful, awful deal. It's an iteration on the F-22 that is expected to cost 1.7 trillion dollars in total. An absolutely unimaginable sum of money.

https://www.gao.gov/products/gao-22-105943

[ranger207]

It's $1.7 trillion in 2023 dollars (I think) total costs across the entirety of the program until 2070 (not sure if the number is "starting today" or "from the start of the program in ~1993") for ~2000 planes for the US and ~1000 for allies (although I don't think the $1.7 trillion includes allies). But the question isn't "how much does the F-35 cost", it's "how much more/less does the F-35 cost compared to whatever else would fulfill its place". Would that be modernized F-15s and F-16s? Would those be able to fulfill the requirements set by the Air Force and indirectly by Congress? Or would there be another program instead that might cost even more than $1.7 trillion across ~50 years (or 80 if counting from the start of the program)?

Also, the F-35 isn't an iteration on the F-22. It's an entirely new airplane. It's a bit worse in aerodynamics but has far better sensors and electronics, reducing the importance of aerodynamics in the first place. In a dogfight the F-22 is better; in a realistic engagement involving multiple platforms and missions being performed at once with air, sea, and land targets and allies, the F-35 is better.

The F-35 program was absolutely mismanaged in its early years and it's a crime that nothing was done about that. There's parts of the program that are mismanaged today (see [0] for examples of what the Air Force is trying to do to avoid those problems with their next fighter). But the program now isn't substantially worse than what other fighters went through, and despite all the program's failings the product itself is fantastic

[0] https://www.thedrive.com/the-war-zone/avoiding-f-35-acquisit...

[oatmeal1]

It's an iteration because it is basically just a more versatile F-22. But versatility isn't all that useful since we have bases all over the world*, and other similarly stealthy aircraft can perform surveillance and ground attacks. The F-22 is already fully capable of next-gen A2A combat.

[dragonwriter]

> F-35 is an awful, awful, awful deal. It's an iteration on the F-22

No, its not. While the program was initiated after the program that built the F-22 its a complement with a different set of niches, not an iteration on the -22. Loosely, the F-22 was the successor to the Air Force’s F-15s, and the F-35A, F-35B, and F-35C, was the successor to...every other contemporary fighter and fixed wing attack aircraft in the US Air Force, Navy, and Marine Corps inventory.

[jes]

Apparently the Air Force is planning a new fighter program[1], which I guess is subsequent to the F-35 program.

I wonder where the money to pay for this program will come from. My understanding, which may be wrong, is that interest payments and social spending is going to significantly reduce what can be spent on defense. Corrections are welcome.

[1] https://www.defenseone.com/business/2023/05/usaf-opens-biddi...

Edit: Delete redundant phrase.

[Mistletoe]

Powerpoint was created in 1987 and it was all downhill from there according to the military.

https://www.theatlantic.com/politics/archive/2010/04/why-the...

[Psyladine]

Not just for military:

https://mcdreeamiemusings.com/blog/2019/4/13/gsux1h6bnt8lqjd...

Turns out trying to contain a complex system within a simple system of abstractions is a trendline towards disaster for any enterprise.

[katbyte]

Indeed https://m.youtube.com/watch?v=aZ-7U95LYTo

[marcus_holmes]

Thanks for the link, that's fascinating, and resonates so much. Do you know what they used instead?

[hindsightbias]

I never understand this belief. The A-12 was only secret 20 months before the announcement so it wasn’t any mystery for long. The idea that there is some supermagic is weird. Materials science of titanium is known. It was new then. Turboramjet theory was novel then, but I read about the internals in the late 70’s in Airpower magazine.

Such a belief means there must be some unknown material or physics that has been embargoed, successfully, for decades.

There’s no there there to be staggered by. Look at a half century of fusion physics or billions on multiple failed hypersonic research. Shit is hard. There are no shortcuts.

[sizzzzlerz]

They had Kelly Johnson in 1964. He is, quite literally, the godfather of high-speed aircraft including the U-2 and the A-12/SR-71. He was not only a highly skilled engineer, he was a manager of the first order. A former colleague of mine had the privilege of working for Johnson early in his career and said that he'd never worked for a better boss. I believe it.

[carabiner]

I've got a lil titanium bowl for camping. Feels like alien material, it's so light and feels like you could snap it, but then it's incredibly strong. I used it in the oven last night to make TikTok feta pasta. No worries on being oven safe as its melting temp is 3,000°F.

[simlevesque]

> No worries on being oven safe as its melting temp is 3,000°F.

Two things:

- Your bowl is most likely not pure titanium and is probably made of an alloy.

- Over 1,200F titanium produces titanium dioxide and may give you titanium dioxide poisoning.

[carabiner]

It's grade 1 unalloyed titanium from Snow Peak: https://www.snowpeak.com/blogs/explore/ultralight-everything with the lowest oxygen content. Your hazard warnings are noted though, and I definitely will keep it at lower temps.

I've also got their titanium flask. I had it engraved from a random guy on youtube who had experience engraving on Ti, because everyone else I contacted (mostly jewelry shops) could only anodize it.

[AlbertCory]

My oven only goes to 500F. Some go to 550F. Even Ooni's are 1000F at most.

What does yours do?

[simlevesque]

Well most oven won't burn any of your cookware no matter the material.

I just wanted to emphasize that there are danger below 3,000F.

[flaminHotSpeedo]

I'll bear that in mind the next time I decide to make lasagne in a crucible

[garaetjjte]

>won't burn any of your cookware

Except PTFE coatings, which releases toxic gases above ~260°C/500°F

[AlbertCory]

except this post was originally about titanium.

[maybecorrect]

I'm pretty sure titanium dioxide is pretty inert. It's a primary ingredient in sunscreen and diaper cream.

Otherwise, I agree with your point.

[flangola7]

Outside the body is one thing. The EU banned it as a food additive last year and some US states are considering it too. TiO2 has genotoxic traits, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8323234/

[biztos]

I always found it odd that my acrylic paint and my toothpaste share this ingredient.

[twright0]

Dihydrogen monoxide too!

[maybecorrect]

Correcting myself, I was thinking of Zinc Oxide. But it's still pretty inert. I wouldn't want a plate of it, but whatever level of toxicity it possesses, it is low enough that it requires careful study to detect.

[petsfed]

If there was a way to bend this particular exchange into the style of the article, I would. Its definitely in the same spirit.

[wkat4242]

This sounds like a job ChatGPT would excel at :) I will leave actually doing so as an exercise for the reader.

[antod]

Our wedding rings are titanium. The engineering geek in me loves it for nerdy reasons, and the metal allergies in my wife love it for other reasons.

[alsodumb]

My materials science professor always used ring as an example in intro to matse classes of what not to do with titanium.

His point was that if you ever get into an accident and the first responders have to cut your ring for whatever reason (MRI machine, etc.), literally none of their tools would be able to do that on a titanium ring. None of the tools in hospital would work either. It may not always be feasible to pull it out the usual way.

Take it as you will.

[lightedman]

"His point was that if you ever get into an accident and the first responders have to cut your ring for whatever reason (MRI machine, etc.), literally none of their tools would be able to do that on a titanium ring"

As a somewhat-experienced jeweler, titanium is not terribly-difficult to work. It's a pain to solder and weld (I use it for wire-wrapping in various gauges,) but cutting it is relatively easy, a good pair of hardened-steel thick wire cutters will absolutely shear it.

[debatem1]

Unfortunately, this is an urban legend. While titanium is amazing stuff a normal ring cutter can go through it.

[sokoloff]

I got Tungsten Carbide rings for that reason (and they happen to also be extremely inexpensive). They’re very hard (scratch resistant) in everyday use, but also quite brittle and easy to shatter to remove if needed for a finger injury.

[wkat4242]

Titanium is more flexible and softer than steel. It also has a similar melting temperature.

I've heard it's just harder to machine because it's more flexible so it tends to bend away from the cutting tools, as far as I understand. Not because it's so strong. But I don't know much about machining so this is second-hand knowledge.

It's just a hell of a lot lighter than steel which is why it's so great for cutting-edge aviation stuff. It's much stronger than aluminium. It's the strength/weight combo that makes it special.

[phone[phone]]

If it's that dire then I'll just take losing the finger.

[jacquesm]

Try working it with regular tools and you'll be even more amazed. It's incredible stuff.

[Tangurena2]

The early 80s Corvette used titanium for the air filter cover. There had to be all sorts of bulletins for mechanics. Even though the cover was held on by large plastic thumb screws (and thus needed no tools for removal) it was a very convenient flat spot in the center of the engine compartment for placing tools on. The cadmium coating on hand tools will cause titanium to corrode, so don't use ordinary hand tools.

[jacquesm]

That's super interesting, I did not realize that. Isn't Cadmium banned nowadays? It's a pretty bad compound to ingest, especially in dust form. Not quite Beryllium Oxide but not exactly flour either.

[carabiner]

Yeah I used to work in aerospace (defense) and was shown a large part, about 3 feet wide, with very complex geometry that was machined from a huge solid chunk of titanium. They said that one part was worth $1 million, on a vehicle that cost total $80m or so. I'm guessing a lot of it was due to difficulty in fabrication.

[peteradio]

I'm not sure how to take this comment. Is it unworkable or surprisingly workable?

[jacquesm]

Very much unworkable. I got a chunk of titanium tubing at some point of my more metal oriented years and tried to do something useful with it, it ate up my tools pretty quickly. Typical standing time for a regular HSS bit was < 1 hole. Carbide did a bit better, but still that too went much faster than usual.

[nickff]

Titanium is very hard to work with; for instance the carbide coatings on many drill-bits can cause it to degrade over time. Tooling for production of the blackbirds was a challenge in and of itself, as little was known about working with titanium at the time.

[VBprogrammer]

It's quite well known for being difficult to machine generally.

[jasonwatkinspdx]

The more you cut titanium the harder it gets. It can eat even carbide drill / mill tools. Welding it is a nightmare.

[SkyMarshal]

/second that book, one of the best on US aviation history and engineering.

Also iirc, ironically the technique for shaping the F-117 to reflect away radar came from a Soviet journal article on shaping nosecones to minimize their interference on radar emanating from them.

[p_l]

Another fun thing is that claims about no computers being used for A-12/SR-71 are mostly boasting possibly to avoid mentioning then black project details, like CIA buying a custom computer (PDP-2) to do calculations on A-12 shape.

[vegasbrianc]

Can also recommend this book. Good read.