For those that want to know more about the Buick engines and their replacement, here's [0] a writeup about it.

[0] https://www.thesr71blackbird.com/Aircraft/Engines/starting-t...

> the engine ran too hot for electronics, so they designed a hydraulic mechanical computer responsible for regulating various inputs

There was a proposal at one point for NASA to deploy a 21st-century automaton to Venus because the atmosphere is too corrosive for an electronic computer. Supposedly it would have delivered its data to an orbiter using a balloon and then the orbiter transmits the information over radio. I really wish they'd do that, I would love to see what could be done with mechanical computing using modern technologies.

Unfortunately there aren't a whole lot of situations where clockwork logic makes more sense than semiconductors.

I remember quite well the day the auctioned off a unique "jet fuel analyzer" that was used to do some of the specialized testing for these exact aircraft.

It was not a benchtop unit, it was a forklift model :\

400 cubic inches for 401 horsepower each. Pushrods, two valves a cylinder.

This is nothing to celebrate.

I'd second that. I saw the surviving M-21 in Seattle. The highlight of the visit. If you get the chance, well worth your time

Big shout out to the Udvar Hazy Center in Chantilly, Virginia which has both an SR-71 and the Discovery Space Shuttle, as well as a bunch of other really interesting aircraft.

While i haven't seen SR-71, i have been to the Beaulieu Motor Museum (pronounced "byoolee" fyi). They have a land speed record hall. Those machines also have a presence. It is as if they are projections from the noosphere into the realm of physical stuff.

Also a Porsche 917. Incredible collection.

The Pima Air and Space museum in Tucson Arizona is incredible and has a SR-71. Highly recommend.

I think we can look to the SLS [1] for the answer there. It was basically NASA's answer to (amongst other things) get to the Moon in a kind-of-new way. For some historical context we first man a man in orbit in early 1962, so that was just barely starting to appreciate the systems involved in space. Kennedy would give his 'To the Moon' speech in late 1962. We'd then land a man on the Moon less than 7 years later.

The SLS started in 2011. 15 years later, it finally managed a manned flyby. The entire program has generally been an endless series of errors and mishaps, and the Moon flyby probably should never have happened, but was greenlit for political/managerial reasons - highly reminiscent of Columbia and Challenger, but with a better outcome owing purely to good fortune.

Not only has it been an endless series of mishaps over an increasingly absurd timeframe, but the program has already been obsoleted by the Falcon Heavy, to say nothing of the ongoing development of Starship. It has a lift capacity of about 50% more than the Falcon Heavy, but one SLS launch costs as much as 40 Falcon Heavy launches, so it's existence just doesn't make any sense, at least not as a space launch system.

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It seems likely that NASA would have been much better advised to have simply revived the Space Shuttle or perhaps even further back rather than trying to do something from scratch, simply because when you do it from scratch you end up trying to iterate on top of something that you no longer necessarily have the expertise or human knowledge of how to create.

I think where intuition fails a lot of us (myself included) is that in the software world if you have the code/documentation for something then building it is trivial. But in the hardware world, even if you have all the instructions and knowledge, actually applying that know how to create a working project is still very far away, through certainly nowhere near as far away as if you have started from scratch.

[1] - https://en.wikipedia.org/wiki/Space_Launch_System

I would bet good money it's one of two things:

a) Some clearly preposterous order that originated with the demented commander in chief, and they're just going through the motions. Same concept as ordering steam catapults put back on aircraft carriers.

or

b) Intentional misdirect/bait to send various groups of people off in a wrong direction as cover for something else entirely.

Up until relatively recently, the Saturn V (and the F1 engine) was the most powerful rocket ever made, even though it's almost 60 years old. Now I believe both SLS and Starship are more powerful.

So this led to the obvious question: why didn't we just recreate the F1 engine and the Saturn V? It turns out there were lots of reasons:

1. Materials science has changed. You can't necessarily make the same materials you made back then. And substituting them might have consequences on certification and testing that would make it much more expensive than a simple recreation;

2. We didn't necessarily know how to. Surprising as it sounds, the Saturn V program was pretty rushed. The engines and rockets were essentially handcrafted. Lots of things were documented but not necessarily everything. Even if it was, has that documentation been lost?

3. Loss of expertise. There's probably hardly anybody left who made those engines. Any complicated production line relies on reinforcing and building expertise through training and repetition. You'd have to build that from scratch. This is a common problem with any major weapons program. As soon as you stop making a particular weapon, it's almost impossible to restart it very quickly;

4. We don't necessarily have all the machining and secondary processes that existed then;

5. Advances in technology mean we can do better things now. For example, we can 3D print parts that we had no way of making them previously. It simply wasn't possible. This has come up in commercial aviation where modern aircraft (eg 787/A350) and their respective engines make heavy use of 3D printed parts, something the 747 could never have possibly have done;

6. Even if you can make all a complete system, what's your production capacity? The capacity for Saturn V rockets was quite low and because it was essentially bespoke, it couldn't be scaled. One of the impressive things about the Falcon 9 system is just how many of those rockets SpaceX could produce, even before extensive reuse of first-stage boosters. Capacity is something that almost has to be built in from scratch and it impacts everything. For example, a bunch of weapon systems have been depleted by the Iran War (eg Patriot interceptors, Tomahawks). You can't just turn a knob to ramp up production meaningfully. And where you can, it's incredibly expensive.

This is also a big part of China's current manufacturing advantage. There's an awful lot of standardization and regional specialization. You need a part? The factory that makes it is probably down the road. So certain things get made in Shenzhen because everything you need is also made in Shenzhen. This also means you can react very quickly, something a factory in the US could never do because it lacks that ecosystem.

They discovered all sorts of weird things when they made the original Blackbird. For example, titanium is so hard that they had to use special tools to machine parts like the panels. Well, in doing so they discovered that using cadmium in some tools to make them operate at higher temperatures and against harder materials would "poison" the titanium fatally.

So if you built a new hypersonic airframe now, would you use titanium? Do we have better alloys? We've had a lot of advances in single-crystal manufacturing for metals that have, for example, made jet engines incredibly reliable. And this btw is something China has had massive difficulties reproducing, at least for now. And they've spent decades trying.

As a simple example of this, there was a guy who went out of his way to make an electric toaster from scratch [1]. This is a relatively simple device but it shows how many inputs there are, which each have production lines (eg steel, aluminum and/or plastic). Now imagine what goes into a military plane that needs to fly at Mach 3-4.

[1]: https://www.ted.com/talks/thomas_thwaites_how_i_built_a_toas...

Guessing this project was also a way to pay Russian engineers while the Soviet Union collapsed with the goal to do "technology transfer" and prevent them from working for NK and the like as a way to make ends meet.

No Top Gun movie series then. :)

Ha ha, that would be a fun project. We might need a bigger basement, though :-)

Particularly toxic boron-enriched fuel at that, to sustain those same high temperatures.

https://en.wikipedia.org/wiki/JP-7

The engine cores alone expand 6” when they heat up.

The SR-71 was never designed as an interceptor, and would require extensive modifications to carry and employ weapons. Not going to happen. There was an earlier YF-12 interceptor program but it never proceeded beyond the prototype stage.

High-altitude balloons are hardly a new threat. They have been used for decades, although some recent Chinese models are more capable than before. Regular tactical aircraft already in the US inventory are perfectly capable of shooting them down.

https://www.af.mil/News/Article-Display/Article/3288579/f-22...

The service ceiling of the SR-71 is still well beneath the altitude of a modern balloon. The speed isn't necessary, and it's altitude record has been beaten by other modern jets.

If we're spitballing solutions, balloons are slow, fragile and move in relatively predictable paths. An F-15 could reach the same altitude, and launch it's own balloon with a small solid-fuel booster that also corrects the trajectory. If the interceptor balloon could get within 1-2km of the target balloon, then a cheap kinetic weapon firing HEI projectiles might be enough to destroy it.