That story (or a variation on it) was in Ben Rich's Skunkworks memoirs, yep.
The radar demonstrator's RCS was considerably smaller than a bird—more on the order of a large bird's eyeball. Birds sitting on the test stand definitely would be noticeable.
According to Ben Rich in Skunk Works, the challenge was in creating a design that broke down into a series of triangles when viewed from every major angle. 90-degree angles provide clear radar reflection, so everything had to be oblique and obtuse angles. (Contrary to popular opinion, stealth is far more a product of an aircraft's shape than anything else. Radar absorbing material absolutely helps, but shape is the critical factor—even more so than size. An enormous F-117A-shaped aircraft would have pretty much the same radar cross section as a small one.)
And they did it—when you look at the Have Blue demonstrator or the F-117 final planform, it's all triangles—everything is triangles. The resulting design is unstable on all 3 axes and wouldn't work without fly-by-wire, but it does work.
The usage of triangular facets was a limitation of the computing power available to engineers in the 70s when Have Blue was being designed. More modern stealth airplanes like the B-2 and the F-22 have fewer facets and more curves because they were built with supercomputers that could work out the complex radar cross section equations necessary.
There is a really cool book called Skunk Works, which talks about this technology-race during the cold war. I recommend it for anyone interested in reading about the stealth tech development.
I seem to recall, in Ben Rich's book "Skunk Works", more engine wasn't enough. They had to use the computer to constantly manipulate the control surfaces to keep the thing in the air.
I might as well start.
Skunk Works -- This is a memoir by Ben Rich of Lockheed's Advanced Development Programs division(AKA Skunk Works). If you're interested in aviation, I'd highly recommend it! Ben Rich lead the Skunk Works during development of the F-117 Nighthawk and the development of stealth technology(including a stealth ship for the Navy that never got the green light). He also worked on the U-2 Dragonlady, and designed the engine inlets for the SR-71 Blackbird.
The Machine that Changed the World -- I'm currently working on this one, so I don't have a fully developed opinion just yet. So far it's pretty neat. This is an expositional work about the Toyota Production System, and similar aspects of industrial engineering(dubbed Lean Production) that were developed in Japan after WW2. The authors have a tendency to proselytize it seems like, but maybe that's for good reason. It's not my area of expertise.
His second in command at Lockheed, a man named Ben Rich also wrote a very good book: https://www.amazon.com/Skunk-Works-Personal-Memoir-Lockheed/...
The story of the development of the Stealth Fighter is absolutely riveting. The book to read is:
Skunk Works by Ben Rich. Ben Rich was the head of Lockheed Martin's "Skunk Works" division that developed this amazing airplane. The book reads like a Tom Clancy thriller, but it's non-fiction and all true. Deserves the incredible 4.8 average star rating on Amazon, everyone loves this book.
When they were testing the car-sized wooden model of the initial stealth airplane design, the radar operator at first thought the model had fallen off the 12 foot pole it was mounted on. The radar was only 1500 feet away from the model. Then, the radar operator all of a sudden picked up the model. A crow had landed on top of the model and the radar saw the crow. When the bird flew off, the model of the aircraft was invisible again. The stealth design technology was so unexpectedly incredible, they had to spend half a million dollars designing a new stealth pole, because the radar would see the pole.
If I remember correctly, the radar cross section of the final stealth fighter -- the first true stealth aircraft ever built -- was the equivalent of a marble, roughly the size of an eagle's eyeball.
Edit: Formatting, typos
My personal favorite is Skunk Works: A Personal Memoir of My Years at Lockheed
One of my favourites. My wife also loved it.
It's great that you brought up "Sled Driver", I'm actually currently saving up to buy a copy. Brian Shul still has new copies available on his website for $250. I think the copies that go for very high prices on eBay are the first editions or some of the special commemorative versions.
May I ask your opinion on the print quality of "Sled Driver"? I know Shul is a photographer, in addition to being a former SR-71 pilot, so I assume the photographic print quality is quite high. Have your read his companion book "The Untouchables"?
Want to build a Mach3 aircraft in the days when most people thought jets were pretty clever?
Want to do it in <2years using materials that had never been used in a plane before - and do it on budget.
And repeat the success with half a a dozen other projects.
And it's described in a book that everyone in technology (or management) should read http://www.amazon.com/Skunk-Works-Personal-Memoir-Lockheed/d...
At the time, I recall a number of people who read the book bemoaning 1991 as a bygone era of opportunity, as if all the good ideas and opportunities to invent had been "used up". Interesting how different people take the same text as self-defeating vs inspiring.
Also, on the topic of inspirational books, I always have to mention Skunk Works, one of my all-time favorites.
This is not a civil engineering book, but one of my favorite 'engineering' stories is "Skunkworks" about Lockheed's secret development division.
Other than that I recommend:
"Traffic, Why we Drive the way we do"
"Rust: The Longest War"
The SR-71 is, to me, for sure the greatest plane ever built. I highly recommend reading Skunkworks .
That TEB he mentions for the ignition system is nasty, nasty stuff. It autoignites at 20 C below, burns at 3000 C and boils at 95C(meaning, it has to be stored nearish to the cockpit). Its necessary to ignite the JP-7 (Jet Propellant 7), which is intentionally hard to ignite as the tanks can get up to 300C. Its a very careful mix, which is unsual- gasoline, oils and jet fuels aren't really a mix typically, they are just pulled at different points in distillation. JP-7 is so hard to ignite you can hold a lighter to it to no effect. JP-7 has a ton of additives, for extra lubrication, to add some mild self-oxidation for a little extra oomph, and A-50, which obscures the radar and infrared signatures of the exhaust. There isn't a single part on that plane which isn't a marvel and an engineering masterpiece. Skunkworks was a bunch of guys running around asking each other for the impossible, with Kelly Johnson at the top dispensing genius and expecting it from everyone on his team.
So the fuel is stored in tanks that reach 300C. The fuel itself reaches 180C. The outside of the windshield gets to 260C, and during normal operation the inside of the windshield is 120C, again obviously requiring special glass. Don't touch it. The cockpit is kept at... 60C, I think? Cold enough to make a noticeable heat gradient in the cockpit. Without a flight suit you would 1) not last long and 2) feel like you were sitting in front of a stove. That massive amount of heat gets dumped into the fuel before it gets burnt using an absolutely MASSIVE heat exchanger. It caused them a whole lot of headaches before they said fuck it, lets just do it. Its powered directly by a bypass from the compressors. The air in the compressors is 400C. Any problem at all in heat exchanger would kill the pilot in seconds, if not instantly. They are kept cool by air at 400C, moving heat into fuel that is hotter than the cockpit. Its witchcraft. They tested the thing by putting it inside a giant furnace because they wanted to be 100% sure it would work. Because its terrifying.
And thats just the air conditioning system. THIS PLANE IS SO COOL
If you geek out on this kind of stuff, this a great book...
Skunk Works: A Personal Memoir of My Years at Lockheed by Ben R. Rich