With an RCS of an Eagle’s Eyeball the F-117 Nighthawk was one thousand times less visible than the D-21, the least visible shape previously produced at Lockheed’s Skunk Works

With an RCS of an Eagle’s Eyeball the F-117 Nighthawk was one thousand times less visible than the D-21, the least visible shape previously produced at Lockheed’s Skunk Works

By Linda Sheffield Miller
Nov 19 2023
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The F-117 Nighthawk

The Lockheed F-117A was developed in response to an Air Force request for an aircraft capable of attacking high value targets without being detected by enemy radar. By the 1970s, new materials and techniques allowed engineers to design an aircraft with radar-evading or “stealth” qualities. The result was the F-117A, the world’s first operational stealth aircraft.

SR-71 T-Shirts
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.

The first F-117A flew on Jun. 18, 1981, and the first F-117A unit, the 4450th Tactical Group (renamed the 37th Tactical Fighter Wing in October 1989), achieved initial operating capability in October 1983.

A total of 59 F-117As were built between 1981 and 1990. In 1989 the F-117A was awarded the Collier Trophy, one of the most prized aeronautical awards in the world.

F-117 Nighthawk low RCS

The F-117A program demonstrated that stealth aircraft with a low radar cross section (RCS) could be conceived, designed and developed, as the following story that appears in Ben Rich’s Book “Skunk Works” proves.

Rich (who served as the second vice president of Lockheed’s Skunk Works after Kelly Johnson) recalls that time Denys Overholser, engineer and radar specialist for Lockheed’s Skunk Works, spoke to him about the first completely stealthy airframe, the F-117.

KC-135Q, F-117s and A-7

The Hopeless Diamond

“Boss,” he said, handing me the diamond-shaped sketch, “Meet the Hopeless Diamond.”

“How good are your radar-cross-section numbers on this one?” I asked.

“Pretty good.” Denys Overholser grinned impishly. “Ask me, ‘How good?’”

I asked him and he told me. “This shape is one thousand times less visible than the least visible shape previously produced at the Skunk Works.”

“Whoa!” I exclaimed. “Are you telling me that this shape is a thousand times less visible than the D-21 drone?”

“You’ve got it!” Denys exclaimed.

“If we made this shape into a full-size tactical fighter, what would be its equivalent radar signature… as big as what—a Piper Cub, a T-38 trainer… what?”

Denys shook his head vigorously. “Ben, understand, we are talking about a major, major, big-time revolution here. We are talking infinitesimal.”

F-117A print
This print is available in multiple sizes from AircraftProfilePrints.com – CLICK HERE TO GET YOURS. F-117A Nighthawk (Stealth) 49th OG, 8th FS “The Black Sheep Squadron”, HO/88-843, Holoman AFB, NM – 2008

As big as an eagle’s eyeball

“Well,” I persisted, “what does that mean? On a radar screen it would appear as a… what? As big as a condor, an eagle, an owl, a what?”

“Ben,” he replied with a loud guffaw, “try as big as an eagle’s eyeball.”

Although officially retired in 2008, many F-117s remain airworthy and are used to support limited research and training missions (such as conducting dissimilar air combat training sorties with USAF and US Navy aircraft) missions based on overall cost effectiveness and their ability to offer unique capabilities.

I am sure that Ben Rich is smiling down from heaven knowing that his baby is still active.

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

Photo credit: Lockheed Martin and U.S. Air Force

Premium F-117
This model is available from AirModels – CLICK HERE TO GET YOURS.

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Linda Sheffield Miller

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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Comments

  1. Richard G Paquette says:

    RCS of an eagles eyeball? The flaw is, eyeballs don’t travel at five hundred miles an hour.

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