SR-71: Now, That Was Some Airplane

Amazing plane. Though for this forum, not very good mileage. From 0.3 to 0.6 mpg (of JP-7), with two passengers and a lot of cameras. Surprisingly, the most efficient mileage was at Mach 3+ (I presume in part due to the very high altitude and consequent reduction in drag).

Also the turning radius at those speeds was a few Western states, so don't try to parallel park at Mach 3.

 

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Some people think that the performance of the SR-71 might have been partially responsible for the demise of the North American B-70:

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Sonic booms aplenty for both, but higher altitudes tended to change how folks on the ground heard them, from a sharp clapping sound, to more of a rolling thunder that didn't damage buildings(!) and whatnot.

My Dad was involved with this Air Force project, called "Operation Bongo" of all things; they subjected Oklahoma City (I think it was, yes, according to Wikipedia) to, like, a LOT of sonic booms, over the course of many months. Those ones included some lower level supersonic flights that actually broke windows and cracked plaster (though it was discovered that many of the claims were actually bogus!).

These tests did, however, prohibit the Concorde from flying domestic US routes, since it was not allowed to go supersonic over the US mainland...and, along with environmental and noise concerns (and the Vietnam War, and exponentially rising fuel costs) killed the Boeing 2707 SST project entirely.

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From Wikipedia:

Starting on February 3, 1964, the first sonic booms began, eight booms per day that began at 7 a.m. and ended in the afternoon. The noise was limited to 1.0 to 1.5 pound-force per square foot (48 to 72 pascal) for the first twelve weeks, then ramped up to 1.5 to 2.0 psf (72 to 96 pascal) for the final fourteen weeks. This range was about equal to that expected from an SST. Though eight booms per day were harsh, the peak overpressures of 2.0 psf were an order of magnitude lower than that needed to shatter glass, and are considered marginally irritating according to published standards. The Air Force used F-104 and B-58 aircraft, with the occasional F-101 and F-106.

Oklahomans initially took the tests in stride. This was chalked up to the booms being predictable and coming at specific times. An FAA-hired camera crew, filming a group of construction workers, were surprised to find that the booms signalled their lunch break.

However, in the first 14 weeks, 147 windows in the city's two tallest buildings, the First National Bank and Liberty National Bank, were broken. By late spring, organized civic groups were already springing into action, but were rebuffed by city politicians, who asked them to show legislators their support. An attempt to lodge an injunction against the tests was denied by district court Judge Stephen Chandler, who said that the plaintiffs could not establish that they suffered any mental or physical harm and that the tests were a vital national need. A restraining order was then sought, which brought a pause to the tests on May 13 until it was decided that the court had exceeded its authority.

Pressure mounted from within. The federal Bureau of the Budget lambasted the FAA about poor experiment design, while complaints flooded into Oklahoma Senator Mike Monroney's office. Finally, East Coast newspapers began to pick up the issue, turning on the national spotlight. On June 6 the Saturday Review published an article titled The Era of Supersonic Morality, which criticized the manner in which the FAA had targeted a city without consulting local government. By July, the Washington Post reported on the turmoil at the local and state level in Oklahoma. Oklahoma City council members were finally beginning to respond to citizen complaints and put pressure on Washington.

The pressure put a premature end to the tests. On July 30, the tests were over. A Oklahoma City Times headline reported: "Silence is deafening!" Zhivko D. Angeluscheff, a prominent hearing specialist serving with the National Academy of Science, recalled: "I was witness to the fact that men were executing their brethren during six long months ... with their thunder, the sonic boom, they were punishing all living creatures on earth."

 

<div class='quotetop'>QUOTE(Pinto Girl @ Nov 21 2007, 11:13 PM) [snapback]542835[/snapback]</div>

Although I consider the Valkyrie the coolest airplane ever built, I doubt the SR-71 is what did it in. The Valkyrie had some severe control problems, and besides, the SR-71 was a small production spy plane and the Valkyrie a bomber which was to number into the hundreds.

A cool video of the Valkyrie in flight . . .
http://www.dfrc.nasa.gov/gallery/movie/XB-.../EM-0039-01.mpg

A very good Valkyrie web site . . .
http://www.labiker.org/xb70.html

If you have the chance to see the Valkyrie at the Air Force Museum at Wright-Patterson AFB in Dayton, OH . . . it is an incredible sight!

 

Great article!

I've flown in the Concorde, which now seems like a Piper compared to the SR-71.

 

How lucky are those American citizens to be used as guineapigs by their own elected government. Lucky ducks!!

 

i was at March AFB in Riverside, CA on the flightline when and was able to see a demonstration of the Blackbird including a mach 2 touch and go vertical to 20,000 feet... very impressive

 

<div class='quotetop'>QUOTE(patsparks @ Nov 22 2007, 04:03 AM) [snapback]542860[/snapback]</div>

Come to think about it, I couldn't agree more.
I remember, as a kid, growing up in Sacramento and hearing sonic booms - undoubtedly from SR-71s taking off and landing at Beale AFB . . . about 30 miles north (as the Blackbird flies) from Sacramento.

Beale AFB satellite image with Blackbird static display centered:
http://maps.google.com/maps?ie=UTF8&ll...p;z=18&om=1

I also cherish the memories of hearing rocket motors for the Apollo moon missions being tested at Aerojet here in Sacramento County. It gave us kids something to aspire to, and the feeling of somehow being connected to the moon missions. Kind of like the people in Perth, Australia who got to witness the nighttime firing of the Apollo rockets in space - propelling the ship out of Earth orbit and on its way to the moon.

On my visit in the early 80's, the people of Perth would still mention it. I'm jealous.

 

interesting trivia about the blackbird:

when sitting on the runway it actually leaks fuel because at high mach numbers skin actually tightens up due to the extreme temperatures the aircraft is subject to

 

<div class='quotetop'>QUOTE(SureValla @ Nov 22 2007, 02:47 PM) [snapback]543000[/snapback]</div>

Which isn't a hazard because JP-7 won't ignite even if you drop a lit match into it.

My favorite SR-71 photo:

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<div class='quotetop'>QUOTE(Sufferin' Prius Envy @ Nov 23 2007, 06:58 AM) [snapback]542994[/snapback]</div>

I get the feeling not everyone felt the same way as you with daily sonic booms. If towns people really were so proud of being treated like white mice they didn't show it very well.

Hey you're no orphans though, we had the poms at Maralinga and nuclear bomb testing right here in South Australia. http://en.wikipedia.org/wiki/British_nucle...ts_at_Maralinga

 

<div class='quotetop'>QUOTE(Sufferin' Prius Envy @ Nov 22 2007, 04:28 PM) [snapback]542994[/snapback]</div>

So, let me get this straight: You like the sound of rocket motors, but are bent out of shape that my muffler is *1db* louder than stock...?!?
[laughing]


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In 1992 I cut class and drove out to Edwards with a few guys...someone had heard that one might be going out on a mission. We stayed there all night until the plane took off almost directly over us...SPECTACULAR!!! And, come to think of it, the weather was somewhat similar...
[said, hopefully]

I didn't see those shock diamonds in the exhaust, though, and I don't think it was the dual cockpit version, either.

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I feel like, the sound of rocket motors is actually one of inefficiency...the poor dears are laboring mightily, primarily against the weight of their own fuel. Then...after all that effort...something like a ton or two of mass actually makes it into orbit...?

Ghastly.

 

<div class='quotetop'>QUOTE(Pinto Girl @ Nov 23 2007, 09:46 AM) [snapback]543250[/snapback]</div>

Just a technical point, but the SR-71 is powered by axial-flow turbojet engines, not rocket motors. A rocket motor is little more than a chamber to contain a chemical reaction with a carefully shaped nozzle at one end, usually always operates at maximum power and almost never operates for more than a few minutes (the Space Shuttle is powered by rocket motors). Turbojet engines can't produce anywhere near the power of a large rocket motor, but they can be throttled and are immensely more fuel efficient. Both are ear-splittingly loud.

Even with the "fuel efficiency" of its turbojets vs rockets, all SR-71 flights nonetheless had exactly the same departure profile: takeoff with enough fuel to reach a tanker a few minutes after rotation, top-off from the tanker, then climb to mission altitude. "Enough fuel" to takeoff and reach the tanker was close to the total fuel capacity of the aircraft - such is the enormous cost of high acceleration in the thickness of the lower atmosphere.

MB

 

<div class='quotetop'>QUOTE(Pinto Girl @ Nov 23 2007, 09:46 AM) [snapback]543250[/snapback]</div>

Laughing right back.
I never said one thing about the sound of your new muffler.
Personally I don't care . . . unless it wakes me up at three in the morning like some anti-social cretin who lives somewhere in the neighborhood and every once in a while thinks it's cool to blast his highly modified Harley muffler up and down the street for ten or fifteen minutes. <_<