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Lockheed D-21

Early Jet (1946–1969)

Lockheed D-21 — Fixed Wing
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The Lockheed D-21 was a high-speed, high-altitude unmanned reconnaissance drone developed by Lockheed's Skunk Works in the early 1960s as a stealthier follow-on to the manned A-12 Oxcart for overflights of denied airspace, particularly mainland China. Designed to cruise at Mach 3.3 above 90,000 feet on a single Marquardt RJ43 ramjet, the D-21 carried a single Hycon HR-335 panoramic camera. After overflying its target, the drone ejected a hatch containing the camera and film for mid-air recovery by a JC-130 Hercules; the drone airframe was then destroyed.

Initial launches were from a modified M-21 A-12 mothership at Mach 3 — an arrangement that proved fatal in July 1966 when a D-21 collided with its M-21 launch aircraft, killing one of the two crew. Lockheed switched to launching the redesignated D-21B from B-52H Stratofortress motherships, with a solid-rocket booster providing initial acceleration to ramjet ignition speed. Four operational D-21B missions were flown over China between November 1969 and March 1971, all targeting the Lop Nor nuclear test site. None of the four returned a usable film hatch — the drones were lost or the recovery failed in every case — and the programme was cancelled in July 1971.

Of the 38 D-21s built, several survive in museums including the National Museum of the United States Air Force, the Pima Air & Space Museum, and the Smithsonian's Udvar-Hazy Center. One D-21 lost over China in 1971 was recovered by the Soviet Union, briefly studied, and contributed to the early Soviet Tu-141/Tu-143 reconnaissance drone programme. The D-21's combination of Mach-3 ramjet propulsion and a faceted-edge stealth shape (uncommon for the period) makes it an early ancestor of modern stealthy unmanned platforms like the RQ-4 Global Hawk and the RQ-180.

For Kids — a shorter, friendlier version

The Lockheed D-21 was a super-fast drone made in the 1960s. It was built by a secret team called Skunk Works. The drone could fly faster than three times the speed of sound. That made it one of the fastest flying machines ever made.

The D-21 was designed to fly over places and take photos. It carried a special camera inside its body. After taking pictures, the drone would drop the camera out. A plane nearby would try to catch it in mid-air. Then the drone itself would be destroyed.

At first, the D-21 was launched from another fast plane called the M-21. That plan turned out to be very dangerous. After a bad crash in 1966, the team changed the plan. They started launching the drone from a big bomber called the B-52. A rocket booster helped push the drone up to flying speed.

The D-21 flew four secret missions over China between 1969 and 1971. Each mission aimed at a place called Lop Nor. The drone was smaller than a school bus but could fly higher than most planes ever go — above 90,000 feet! Sadly, not one of the four missions brought back useful photos.

Fun Facts

  • The D-21 could fly at more than three times the speed of sound — faster than almost any plane of its time.
  • It flew above 90,000 feet, which is nearly three times higher than where most passenger planes fly.
  • The D-21 was smaller than a school bus but could outrun nearly anything in the sky.
  • A special rocket booster was used to kick-start the drone after it was dropped from a B-52 bomber.
  • After taking photos, the drone would eject its camera so another plane could catch it in mid-air.
  • The drone was always destroyed after each mission — it was never meant to land.
  • Four missions were flown over China, but not one came back with usable photos.
  • The D-21 was built by the same secret Skunk Works team that made the famous A-12 spy plane.

Kids’ Questions

How fast could the D-21 fly?

The D-21 could fly at more than three times the speed of sound. That is incredibly fast — faster than a rifle bullet. Almost nothing else in the air could keep up with it.

How did the D-21 take pictures and bring them back?

The drone carried a camera inside its body. After flying over its target, it would drop a hatch holding the camera and film. A plane called a JC-130 Hercules would try to catch that hatch while it fell through the sky.

Why did they stop launching the D-21 from the M-21 plane?

In 1966, a D-21 crashed into the M-21 plane that launched it. The crash was very serious and hurt the crew. After that, the team decided to launch the drone from a safer distance using a big B-52 bomber instead.

Did any of the D-21 missions over China work?

The D-21 flew four missions over a place in China called Lop Nor. Sadly, none of the missions worked. The drones were lost or the camera hatches were never recovered, so no useful photos came back.

Variants

D-21
Original variant designed to launch at Mach 3 from the M-21 A-12 mothership. Cancelled after the fatal 1966 launch accident.
D-21B
Redesigned for B-52H launch with a solid-rocket booster for acceleration. Flew four operational missions over China between 1969 and 1971.

Notable Operators

United States Air Force (1969–1971)
Strategic Air Command's 4200th Test Squadron operated D-21Bs from Beale AFB. All four operational missions targeted the Lop Nor nuclear test site in western China.

Frequently Asked Questions

What was the D-21 designed for?

The D-21 was designed to overfly Soviet and Chinese nuclear and missile test sites at Mach 3.3 — too fast and high for any contemporary surface-to-air missile or interceptor. After photographing the target, the drone ejected its film hatch for mid-air recovery and self-destructed.

Did the D-21 ever succeed in its mission?

No — none of the four operational D-21B missions over China between 1969 and 1971 returned usable imagery. Two drones were lost on outbound legs, one disappeared over China, and the fourth's film hatch was lost in a recovery failure. The programme was cancelled in July 1971.

Why was the D-21 retired?

The four operational missions all failed to return imagery, the loss rate was 100%, and reconnaissance satellite imagery was simultaneously becoming both better and cheaper. The Skunk Works also turned its attention to the SR-71 fleet and to early stealth aircraft work.

What happened to the D-21 lost over China?

The D-21 lost over China in 1971 was recovered by the Soviet Union (via Chinese cooperation), briefly studied, and is believed to have informed the early Soviet Tu-141/Tu-143 reconnaissance drone programme. It is not known to have contributed to any specific Chinese drone design.

How fast was the D-21?

The D-21 cruised at Mach 3.3 above 90,000 feet on a single Marquardt RJ43-MA-11 ramjet — slightly faster and higher than its A-12 mothership.

Sources

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