Wednesday, February 09, 2011

Betrayed by Heat: The SR-71 Blackbird

A couple of friends and I went to the Steven F. Udvar-Hazy Center, part of the National Air & Space Museum near Dulles Airport, a few weeks ago. The museum is home to over 160 aircraft, almost as many spacecraft and missiles, and several thousand smaller aviation-related artifacts. What is perhaps most exciting object on display, though, is the one that greets visitors as they first enter the museum -- the SR-71 Blackbird.

[The view you're greeted with upon entering Udvar-Hazy.]

The three of us were particularly struck with the Blackbird. It's not surprising since the plane is the museum's centerpiece, with the pearly white Enterprise peering over its shoulder from the next room.

[A view from behind shows the Blackbird's Delta-wing shape common to many supersonic airplanes.]

The Blackbird was developed by Lockheed Martin's division for secretive projects called Skunk Works. It was designed to replace another stealth aircraft developed by Lockheed Martin's Skunk Works -- the U-2 . The U-2 was created as a high-altitude reconnaissance aircraft (a spy plane) but it was not capable of flying supersonically, or faster than the speed of sound, making it vulnerable to anti-aircraft weapons. The Blackbird can fly above 82,000 ft. (15 and a half miles) and up to speeds of Mach 3.2, or around 2,400 mph.

[The Lockheed Martin Skunk Works livery.]

Developing a high-flying, supersonic airplane came with one giant problem: Heat. As a supersonic airplane flies faster and faster, the friction from air ramming it results in a lot of heat building up around the airplane. To keep it flying functionally, the designers had to find clever ways to keep the Blackbird cool.

[A man checks out an engine intake on one of the Blackbird's two engines. The cone in the center of the engine retracted while the airplane flew at supersonic speeds to help ensure proper airflow into the engine.]

A special fuel that was stable at high temperatures was developed for the Blackbird. According to the SR-71 manual, the fuel was used both as energy for the engine and also as engine hydraulic fluid - fluid used to power certain engine components.

When the airplane was traveling supersonically, the fuel was also used as part of a heat sink. A heat sink is a device that uses a fluid to wick away heat from a solid object. The Blackbird's manual states that without that heat sinking capability, parts of the airplane and its engines would overheat at high Mach speeds.

[A Blackbird engine from behind.]

Though the airplane was designed to be stealthy, it was fairly easy to detect on radar thanks to the large amount of heat coming out of its engines when it traveled at high speeds. According to, the Federal Aviation Administration could track the Blackbird from several hundred miles away by detecting the airplane's exhaust.

[The Blackbird was officially retired in 1990, though two were brought out of retirement in 1995 and are still used by the U.S. Air Force. This Blackbird set four world records on its March 6, 1990, trip from Los Angeles, Calif., to Washington D.C. on its way to its new home in the Udvar-Hazy. It made the journey in 64 minutes, 2 seconds, with an average speed of 2,144 mph.]

The Blackbird had another quirky heat-thwarting feature: It leaked fuel. According to Lockheed Martin, 93 percent of the airplane is made of titanium alloy. Titanium expands as it is heated. To keep the airplane from crunching up like a soda can when it was flying at high speeds, the designers left gaps between its body panels. Consequently, fuel, stored in the airplane's body, leaked out onto the runway before take off. Once airborne and warmed up by friction, the titanium would expand, the gaps would seal and the Blackbird would be refueled before leaving on its mission.

Skunk Works improved upon the Blackbird when it created the F-117 Nighthawk, their first truly stealth airplane. They also collaborated with Boeing to develop the more conventional-looking F-22 Raptor stealth fighter. And who knows what else is up Skunk Works' sleeve these days. Regardless of what it is, I doubt it could ever have the unique personality of its early predecessor - the SR-71 Blackbird.


  1. Top Pentagon Military Officers are also Top Lockheed Martin Salesmen

    Not sated after sacking the U.S. Treasury, like locusts our Military Industrial Complex is swarming around the globe seeking new sources of sustinance. In the photo linked below we see U.S. Air Force Chief of Staff General Norton Schwartz presenting a model of the C-130J-30 Super Hercules to Indian Defense Minister A.K. Antony at a ceremony at the Air Force Station at Hindon near New Delhi, India on Saturday (5 February 2011) to mark the induction of the first of six Lockheed Martin C-130J airplanes purchased for the Indian Air Force.

    U.S. total debt $55.6 trillion, U.S. federal debt $14.1 trillion, U.S. federal deficit $1.5 trillion, U.S. dollar rapidly losing world reserve currency status, as U.S. politicians bought and paid for by multinational corporations (legalized by Citizens United vs. FEC) cut education, close schools, convert asphalt roads to gravel and accelerate America's descent into oblivion so they can pay Lockheed Martin and other greed- and graft-infested government contractors billions for Rube Goldberg defense systems and myriad non-defense boondoggles as unnecessary, unaffordable and unjustifiable as our unending wars for oil and profit. And with the open support of Pentagon top brass, the debt for death and destruction will grow to plague nations around the world:

  2. Pertaining to physics, some of your data is not quite accurate. Of course this is not your error, but like dozens of myths that surround the Blackbirds, disinformation and the secret classifications under special access required and need to know basis not many people know any of the facts.

    As far as the SR-71 skin expanding to seal the fuel tanks, that's a myth. When the airframe heats up, I does not seal the fuel tanks. The tanks are manually sealed using a special blend of 3M brand high temperature sealant. It is applied at certain locations depending on the measured drip per minute rates. When the aircraft flies and reaches operating temperature the fuel still leaks at the same rates, there is just no way the measure it in flight. The amount is so small that the effect is negligible. As the airframe heats up the titanium expands and causes the seems to get bigger.

    The stealthiness of the SR-71's was fantastic for it's time. The proof is that none were ever shot down by the thousands of MACH 5 missiles fired at it. The fact is that the tremendous exhaust would have emitted detectable heat for hundreds of miles if it weren't for one clever trick. This little trick was a material that the Skunk Works had nicknamed "Panther Piss".

    After they retired the Blackbirds, Ben Rich, the SR-71's co-designer and also the Director of Lockheed Skunk Works boasted in his book (memoir) titled "Skunk Works" on page 240.

    "We at the Skunk Works believed that the airplane's height and speed, as well as its pioneering stealthy composite materials applied to key areas of its wings and tail, would keep it and its crew safe, but we fortified that belief by adding a special additive, which we nicknamed "panther piss", that ionized the furnace-like gas plumes streaming from the engine exhaust. The additive caused enemy infrared detectors to break up incoherently."

    This little trick gave the Blackbirds enough advance lead time giving it a reduced intercept reaction factor.

    By now your wondering what the hell is "Panther Piss"?

  3. In 2007, the CIA released the History of the OXCART Program, written by Kelly Johnson, the Blackbird's Chief Designer.

    In that document around 1959, Johnson states-

    Page 4.
    " By this time we were working with P&W on a J58 engine. To overcome the afterburner problem of a large radar cross section return from the aft quadrant, we proposed the use of cesium additive to the fuel. This was first brought up by Mr. Ed Lovick of ADP, and its final development was passed over to P&W. It was eventually a basic part of our cross section reduction methods."

    Page 9.
    "We were able to prove by 1 January 1960 that our concept of shape, additive, and loaded plastic parts had enough promise to warrant going forward with the project."

    Dr. Abernethy was an engineer for P&W (Pratt & Whiney) the Blackbird engine builder. Notice the statement is dated nearly 2 years prior to Kelly Johnson's statement in the OXCART document.

    Below it a quote from Dr. Bob Abernethy's web site, a presentation to the Roadrunners and the J58 Reunion.

    "In late 1957 PW had two top secret, black, engine projects that were to use poison fuels! Not a good idea in the middle of Connecticut, how about the middle of the Everglades?? So I was invited to move to Florida. I was assigned to the J58, a Mach 3 Navy engine. To scrub the poison out of the J58 exhaust we built a huge swimming pool with a tall tower to centrifuge the poison out of the exhaust… If it didn’t work, we might wipe out the Palm Beaches so we were a little nervous. The Navy canceled the poison fuel just before we ran the first test. thank heavens!"

    Dr. Abernethy never knew about about the use of cesium in the jet fuel and to this day the Air Force has no record or information about it's use as it was classified top secret as well as a manufacture trade secret of the fuel suppliers.

    For more information about the phenomenal Blackbirds and to request an authentic sample of it's magnificent heat resistant and extremely rare Beta Titanium, check out