The world of aviation has been one of constant experimentation. Sometimes, alas, the coolest models don't takeoff, or are retired in their prime. <br /><br />Here we take a look at ten planes which, for better or worse, have been retired. <br /><br />Dan Hagedorn, curator of Seattle's <a href="index.php?page=&url=http%3A%2F%2Fwww.museumofflight.org%2F" target="_blank" target="_blank">Museum of Flight</a>, points to the now-defunct Lockheed M-21 Blackbird as one of history's greatest flying machines. The spy plane built to support a CIA program in 1963. It was a precursor to the SR-71 Blackbird, which Hagedorn describes as "the fastest, highest-flying piloted jet in history."
1. Lockheed M-21 Blackbird —
The world of aviation has been one of constant experimentation. Sometimes, alas, the coolest models don't takeoff, or are retired in their prime.

Here we take a look at ten planes which, for better or worse, have been retired.

Dan Hagedorn, curator of Seattle's Museum of Flight, points to the now-defunct Lockheed M-21 Blackbird as one of history's greatest flying machines. The spy plane built to support a CIA program in 1963. It was a precursor to the SR-71 Blackbird, which Hagedorn describes as "the fastest, highest-flying piloted jet in history."
Museum of Flight, Seattle
The well-known DC-10 took its last flight in 2014, 43 years after it first flew in 1971. The American-made "trijet" was famous for having three engines and was thought to launch modern air travel, and the long-haul flight, as we know it today. When manufacturer McDonnell Douglass was merged into Boeing, production of the popular model ceased.<br /><br />"McDonnell Douglas was overtaken by the success of other manufacturers," explains Hagedorn.
2. DC-10 —
The well-known DC-10 took its last flight in 2014, 43 years after it first flew in 1971. The American-made "trijet" was famous for having three engines and was thought to launch modern air travel, and the long-haul flight, as we know it today. When manufacturer McDonnell Douglass was merged into Boeing, production of the popular model ceased.

"McDonnell Douglas was overtaken by the success of other manufacturers," explains Hagedorn.
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Known as the "Flying Pancake," the Vought V-173 was designed during World War II to take off on short runways. <br /><br />"During its first few flights over the Connecticut countryside, it generated a lot of phone calls to sheriff's offices about UFOs," says Bruce Bleakley, museum director at the Frontiers of Flight Museum, where the plane is on a long-term loan from the National Air and Space Museum of the Smithsonian Institution.
3. Vought V-173 —
Known as the "Flying Pancake," the Vought V-173 was designed during World War II to take off on short runways.

"During its first few flights over the Connecticut countryside, it generated a lot of phone calls to sheriff's offices about UFOs," says Bruce Bleakley, museum director at the Frontiers of Flight Museum, where the plane is on a long-term loan from the National Air and Space Museum of the Smithsonian Institution.
Jay Miller, Frontiers of Flight Museum
This is an exterior view of the H-4 Hercules, or Spruce Goose -- a massive sea plane designed and built by American industrialist, aviator, and film producer Howard Hughes in 1947. Six times larger than any aircraft of its time, the Spruce Goose, also known as the Flying Boat, was built to carry 700 troops. Made entirely of wood (mostly birch), it only flew once. It now sits in the<a href="index.php?page=&url=http%3A%2F%2Fevergreenmuseum.org%2F" target="_blank" target="_blank"> Evergreen Aviation and Space Museum</a> in Oregon.
4. Hughes H-4 Hercules —
This is an exterior view of the H-4 Hercules, or Spruce Goose -- a massive sea plane designed and built by American industrialist, aviator, and film producer Howard Hughes in 1947. Six times larger than any aircraft of its time, the Spruce Goose, also known as the Flying Boat, was built to carry 700 troops. Made entirely of wood (mostly birch), it only flew once. It now sits in the Evergreen Aviation and Space Museum in Oregon.
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<a href="index.php?page=&url=http%3A%2F%2Fwww.pimaair.org%2F" target="_blank" target="_blank">Pima Air & Space Museum</a> in Tuscon, Arizona, displays a Fairchild C-82 Packet, a twin-engined cargo aircraft used briefly by the United States Air Force following World War II. The C-82 is perhaps best known for its role in the 1964 film "The Flight of the Phoenix," in which James Stewart flew the plane in Libya.
5. Fairchild C-82 Packet —
Pima Air & Space Museum in Tuscon, Arizona, displays a Fairchild C-82 Packet, a twin-engined cargo aircraft used briefly by the United States Air Force following World War II. The C-82 is perhaps best known for its role in the 1964 film "The Flight of the Phoenix," in which James Stewart flew the plane in Libya.
Courtesy Pima Air & Space Museum
Believe it or not, flying cars have been in existence since the '40s. The Convair Model 118 made a test flight in 1947. Alas, the hybrid vehicle never went into production after its one-hour demonstration flight, in which it had a crash landing due to low fuel, destroying the car body.
6. Convair Model 118 —
Believe it or not, flying cars have been in existence since the '40s. The Convair Model 118 made a test flight in 1947. Alas, the hybrid vehicle never went into production after its one-hour demonstration flight, in which it had a crash landing due to low fuel, destroying the car body.
FPG/Hulton Archive/Getty Images
In 1968, several Taylor Aerocar III's were built, though Hagedorn says they never really took off in the public eye.<br /><br />"They were cumbersome and a little bit underpowered" he admits.
7. Taylor Aerocar III —
In 1968, several Taylor Aerocar III's were built, though Hagedorn says they never really took off in the public eye.

"They were cumbersome and a little bit underpowered" he admits.
Museum of Flight, Seattle
A Church Army canteen worker is seen here handing a cup of tea to the pilot of a Sikorsky R-4 helicopter hovering overhead at an RAF Helicopter School in Andover, England, in 1945. Though not an airplane, the R-4 was the world's first mass-produced helicopter and the first helicopter used by the United States Army Air Forces and the British Royal Air Force and Royal Navy.
8. Sikorsky R-4 —
A Church Army canteen worker is seen here handing a cup of tea to the pilot of a Sikorsky R-4 helicopter hovering overhead at an RAF Helicopter School in Andover, England, in 1945. Though not an airplane, the R-4 was the world's first mass-produced helicopter and the first helicopter used by the United States Army Air Forces and the British Royal Air Force and Royal Navy.
Fox Photos/Getty Images
The Douglas DC-2 was, according to Hagedorn, "one of the most loved (planes) with the Royal Air Force." The Museum of Flight displays the last air-worthy model of the DC-2.
9. DC-2 —
The Douglas DC-2 was, according to Hagedorn, "one of the most loved (planes) with the Royal Air Force." The Museum of Flight displays the last air-worthy model of the DC-2.
Museum of Flight
Of course, no list of retired planes would be complete without the Concorde. The supersonic plane made its final transatlantic flight in October, 2003. British Airways flight BA001 took three hours and twenty minutes to reach New York from London's Heathrow Airport. <br /><br /><em>Feel we left something out? Tweet us at @CNNTravel, or tell us in the comments section. </em>
10. Concorde —
Of course, no list of retired planes would be complete without the Concorde. The supersonic plane made its final transatlantic flight in October, 2003. British Airways flight BA001 took three hours and twenty minutes to reach New York from London's Heathrow Airport.

Feel we left something out? Tweet us at @CNNTravel, or tell us in the comments section.
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