The D-21 Drone and project Senior Bowl: i.e. the SR-71 Blackbird was not the Most Secret Program ever developed by famed Lockheed Skunk Works

By Linda Sheffield Miller
Aug 16 2024

The D-21 Drone and project Senior Bowl

The D-21 Drone and project Senior Bowl: i.e. the SR-71 Blackbird was not the Most Secret Program ever developed by famed Lockheed Skunk Works

At Beale Air Force Base (AFB), in California, you would think that the SR-71 Blackbird program would be the biggest blackest deepest secret.

But you would be wrong.

The biggest secret was Project Tagboard/Senior Bowl.

B-58 navigator recalls dropping Mark-53 nuclear bomb (without plutonium pit) while flying at 500 feet and at 628 knots, low level recce missions, dinner with Doolittle Raiders and Jimmy Stewart
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.

Project Tagboard/Senior Bowl is a relatively unknown project in the history of Area 51 reconnaissance A-12 aircraft. This project was Top Secret from its inception and during the Senior Bowl part of the project, there were less than 100 personnel cleared to work on it.

According to Air Force Test Center History Office documents, all manned flights over the Soviet Union were discontinued by President Dwight Eisenhower after Francis Gary Powers’ U-2 spy plane was shot down May 1, 1960. However even if the US government was planning on using satellites for reconnaissance, the technology was still a few years away and the Central Intelligence Agency (CIA) determined unmanned drones could fill the gap until satellites became viable.

For this reason, in the 1960s the famed Lockheed “Skunk Works” developed the D-21 a highly-advanced, remotely piloted aircraft (RPA) designed to carry out high-speed, high-altitude strategic reconnaissance missions over hostile territory.

The D-21 Drone and project Senior Bowl: i.e. the SR-71 Blackbird was not the Most Secret Program ever developed by famed Lockheed Skunk Works
M-21 and D-21

Launched from the back of the M-21

According to the document Project Tagboard/Senior Bowl Overview by Road Runners Internationale, Project Tagboard/Senior Bowl was the brain child of Lockheed’s Skunk Works’ Kelly Johnson. It consisted of a drone (D-21) mated to a modified A-12 aircraft (M-21), the combination known as MD-21 (mother/daughter).

The project was first conceived in 1962 when Lockheed’s Kelly Johnson got approval from the CIA to add two aircraft to the existing A-12 assembly line. Known as M-21’s, these aircraft were built with a second crew station for the Launch Control Officer (LCO) and structurally enhanced aft fuselage with a large dorsal pylon to carry the new drone atop the rear fuselage. When attached, the wingtips of the D-21 would have only six inches of clearance with the tops of the vertical stabilizers of the mother ship. This combination was known as the MD-21 (mother/daughter).

The D-21 would be launched from the back of the M-21. Ideally, after conducting its reconnaissance mission it would eject a hatch with photo equipment to be recovered either mid-air or after the hatch landed.

The D-21 Drone and project Senior Bowl: i.e. the SR-71 Blackbird was not the Most Secret Program ever developed by famed Lockheed Skunk Works
B-52 – D-21

However, on the fourth flight test, the D-21 experienced an “asymmetric unstart” as it passed through the bow wake of the M-21 causing the mothership to pitch up and collide with the D-21 at Mach 3.25. Crewmembers Bill Park and Ray Torick ejected from the M-21, but Torick opened his helmet visor by mistake and his suit filled up with water causing him to drown.

After the accident and after the death of Ray Torick, a test flight engineer, the M-21 launch program was cancelled but testers still believed the D-21 would make a valuable reconnaissance vehicle and decided to launch the drone from B-52Hs under a top-secret test program named Tagboard. The new code name for the D-21 project became Senior Bowl.

Modified B-52s

It was Kelly Johnson, President of Skunk Works, who suggested to use the B-52. As a result of Johnson’s advice two B-52’s were modified: 61#0021 and 60#0036. Both B-52’s are still in the US Air Force (USAF) inventory. The ultra-secret 4200 test squadron was formed at Beale.

The D-21 Drone and project Senior Bowl: i.e. the SR-71 Blackbird was not the Most Secret Program ever developed by famed Lockheed Skunk Works
D-21 drone.

+Only a few of the men that flew the SR-71 had been read into the program: out of necessity one of the few included my father Richard “Butch” Sheffield, SR-71 RSO who had already been read into Oxcart in 1965. In his unpublished book he writes that on the flightline he was with Bob Spencer, SR-71 pilot. They were taxing out when they saw the B-52 with a drone underneath it. Spencer asked ‘What is that under that B-52?’ My Dad responded ‘I have no idea.’ He couldn’t tell Bob Spencer the truth.

These two B-52‘s were kept away at the end of the runway apart from any other operations.

The D-21s were used on four flights over communist China but none of these missions fully succeeded.

Two flights were successful; however, the imagery could not be recovered from the D-21’s hatch. The other two operational flights ended with one being lost in a heavily defended area and the other D-21 simply disappeared after launch.

D-21 over China and Senior Bowl

The main mission of the D-21 was to fly over China and take pictures of its nuclear weapons test facility in the remote west central of the country near Lop Nor.

An Omega KDC-10 is the first commercial tanker to refuel USAF B-52, MC-130J over Pacific Ocean
This print is available in multiple sizes from AircraftProfilePrints.com – CLICK HERE TO GET YOURS. B-52H Stratofortress 2nd BW, 20th BS, LA/60-0008 “Lucky Lady IV”.

The pictures were supposed to be dropped in the ocean and recovered by the Navy. During the Cold War this information was necessary for the defense of the US.

The fourth and final mission of the D-21 drone took place on Mar. 20, 1971 and was undertaken by D-21 #527. Experts at the 4200th Support Squadron and at Skunk Works concluded that #527 must have malfunctioned. It was thought to have gone down near Lop Nor. This drone is on display in China at their national aviation museum. So, we know that it got close to the target.

Senior Bowl lasted from January 1968 until Jul. 15, 1971. Interestingly, after the fall of the Soviet Union, Ben Rich (then retired president of Lockheed’s Skunk Works) finally had an opportunity to tour Russia himself. While in Moscow, the KGB presented Rich with a gift of what they thought were the remains of a stealth fighter that had crashed in their territory. As it turned out, the wreckage was actually pieces and parts of the lost D-21 Drone!

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, Instagram Page SR71Habubrats and Facebook Page Born into the Wilde Blue Yonder Habubrats for awesome Blackbird’s photos and stories.

An Omega KDC-10 is the first commercial tanker to refuel USAF B-52, MC-130J over Pacific Ocean
This model is available from AirModels – CLICK HERE TO GET YOURS.

Photo credit: U.S. Air Force

Linda Sheffield Miller

Linda Sheffield Miller

Linda Sheffield co-author of Helion’s new book “Ohio to Supersonic: Flying the SR-71 to the Secret World of the Skunk Works,” Linda helped bring her father, SR-71 RSO, Col. Richard “Butch” Sheffield's book to life. Linda grew up on Air Force bases primarily at Beale Air Force Base California. The home of the SR -71. Linda is a graduate of North Dakota State University and taught public school for over a decade as a substitute teacher. Linda writes daily about the SR -71 the A-12 and the U-2 on her various social media accounts. Linda lives in the suburbs of Washington DC with her husband Rodney Miller, they are the parents of three daughters and four grandsons. She is the co-founder of the SR-71 group, Habubrats. Linda has been asked to write articles for the Distinguished Flying Cross magazine, and the Evergreen Museum newsletter. Linda enthusiastically enjoys contributing articles weekly to The Aviation Geek Club.

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