SR-71 Blackbird

Producing JP-7, the fuel that powered the SR-71 Blackbird, caused a nationwide shortage of bug spray. Here’s why.

The SR-71 Blackbird

In the 1960’s, the US Air Force (USAF) developed the SR-71 Blackbird, a plane that could travel more than 3 times as fast as the sound produced by its own engines.

CLICK HERE to see The Aviation Geek Club contributor Linda Sheffield’s T-shirt designs! Linda has a personal relationship with the SR-71 because her father Butch Sheffield flew the Blackbird from test flight in 1965 until 1973. Butch’s Granddaughter’s Lisa Burroughs and Susan Miller are graphic designers. They designed most of the merchandise that is for sale on Threadless. A percentage of the profits go to Flight Test Museum at Edwards Air Force Base. This nonprofit charity is personal to the Sheffield family because they are raising money to house SR-71, #955. This was the first Blackbird that Butch Sheffield flew on Oct. 4, 1965.

Throughout its nearly 24-year career, the SR-71 spy plane remained the world’s fastest and highest-flying operational aircraft. Flying at Mach 3+ from 80,000 feet, it could survey 100,000 square miles of Earth’s surface per hour. And in the off chance an enemy tried to shoot it down with a missile, all the Blackbird had to do was speed up and outrun it.

Its engineering was so cutting edge that even the tools to build the SR-71 needed to be designed from scratch.

JP-7, the SR-71 Blackbird fuel

In fact, given that the Blackbird became so hot because it cruised at a speed of Mach 3.2 conventional jet fuel could not be used in it. A jet fuel with a high flash point, and high thermal stability was required. To satisfy this requirement Shell produced a special blend of fuel called JP-7.

Specifically, JP-7 fuel (referred to as Jet Propellant 7 prior to MIL-DTL-38219) was developed for the Blackbird’s Pratt & Whitney J58 (JT11D-20) turbojet engine. During flight, the SR-71 could attain speeds in excess of Mach 3+, which was the most efficient cruising speed for the J58 engines. However, very high skin temperatures were generated at this speed due to friction with the air. A new jet fuel was needed that was not affected by the heat, so JP-7 jet fuel, with a high flash point and high thermal stability, was developed for this purpose.

JP-7 fuel production caused a nationwide shortage of bug spray

According to the SR-71A Flight Manual, “The operating envelope of the [J58] JT11D-20 engine requires special fuel. The fuel is not only the source of energy but is also used in the engine hydraulic system. During high Mach flight, the fuel is also a heat sink for the various aircraft and engine accessories which would otherwise overheat at the high temperatures encountered. This requires a fuel having high thermal stability so that it will not break down and deposit coke and varnishes in the fuel system passages. A high luminometer number (brightness of flame index) is required to minimize transfer of heat to the burner parts. Other items are also significant, such as the amount of sulfur impurities tolerated. Advanced fuels, JP-7 (PWA 535) and PWA 523E, were developed to meet the above requirements.”

This print is available in multiple sizes from AircraftProfilePrints.com – CLICK HERE TO GET YOURS. SR-71A Blackbird 61-7972 “Skunkworks”

Flit mosquito repellant

Noteworthy, JP-7 production caused a nationwide shortage of bug spray.

Shell Oil developed JP-7 in 1955. Manufacturing several hundred thousand gallons of the new fuel required the petroleum byproducts Shell normally used to make its Flit insecticide, causing a nationwide shortage of that product!

One of the ingredients in JP-7 just so happened to be a crucial part of Flit mosquito repellant. Bearing in mind the huge amount of fuel we’re talking about here, Shell didn’t exactly have enough supply to meet the newly increased demand, so mosquitos everywhere caught a lucky break!

JP-7 had a high flashpoint. It was not flammable and every time an SR-71 needed fuel, tankers were always there, they were terrific and deserve high praise.

SR-71 Blackbird JP-7 fuel used by the Boeing X-51 Waverider

Today the JP-7 fuel is used by the Boeing X-51 Waverider in its Pratt & Whitney SJY61 scramjet engine, with fuel capacity of some 270 pounds (120 kg). As with the SR-71, the X-51A design super-cools this fuel (cooled by extended subsonic flight in the stratosphere; prior to acceleration to supersonic speeds); then, when in supersonic flight, the fuel is heated by its circulation through heat exchangers which transfer to it the heat load of the interior spaces of the airframe. The fuel is then pumped through rotating mechanical parts of the engines and auxiliary mechanical equipment, providing both lubrication and cooling. Finally, at a temperature of nearly 550 °F (290 °C), it is pumped into the fuel nozzles of the engines.

Be sure to check out Linda Sheffield Miller (Col Richard (Butch) Sheffield’s daughter, Col. Sheffield was an SR-71 Reconnaissance Systems Officer) Twitter X Page Habubrats SR-71 and Facebook Page Born into the Wilde Blue Yonder for awesome Blackbird’s photos and stories.

Photo credit: U.S. Air Force

This model is available from AirModels – CLICK HERE TO GET YOURS.
Linda Sheffield Miller

Grew up at Beale Air Force Base, California. I am a Habubrat. Graduated from North Dakota State University. Former Public School Substitute Teacher, (all subjects all grades). Member of the DAR (Daughters of the Revolutionary War). I am interested in History, especially the history of SR-71. Married, Mother of three wonderful daughters and four extremely handsome grandsons. I live near Washington, DC.

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