 When researching for my video on the history of airplane wings, I came across a lot of cool experimental planes. I didn't want them to go to waste, so here are three of the coolest ones I found. Don't forget to subscribe and hit that notification bell so you don't miss out on any future uploads, and let's jump in. First up, the Rutan Voyager. The initial idea for the plane was first sketched out on the back of a napkin before being built in the Mojave Desert over the course of five years, mainly by a group of volunteers. The airframe, largely made of fiberglass, carbon fiber, and Kevlar, weighed 2,200 pounds before more than 7,000 pounds of fuel were loaded on board. That meant that a takeoff, more than 75% of the aircraft's weight, was the insane amount of fuel that would be required to circumnavigate the globe. Voyager came equipped with two propellers, one in the front and one in the back, powered by two separate engines, although the rear propeller was only used during takeoff. Voyager's world record flight took place on the longest runway in the world at Edwards Air Force Base at 801 a.m. on December 14th, 1986, with 3,500 of the world's press and attendance. As the plane accelerated down the runway, the tips of the wings, which were heavily loaded with fuel, were damaged when they unexpectedly flipped downwards and scraped against the runway. You might wonder why the designers didn't realize this would happen in advance, but in the 67 test flights that led up to this flight, the plane had never been fully loaded to capacitate. Contact with the ground caused parts of the wingtips on both sides to be ripped off, exposing the blue foam core, but the pilots determined that the aircraft was still within its performance specifications, despite the damage, and decided to continue west. During the flight, the two pilots had to deal with extremely cramped quarters. To reduce stress, they had originally intended to fly the plane in three-hour shifts, but the plane was so difficult to control while heavily loaded with fuel that it prevented routine changeovers, and so Dick Rutan stayed at the controls without relief for nearly all of the first three days of the flight, not three hours, three days, and that was only about a third of the way into the plane's journey around the globe. Along the way, the pilots had to maneuver around bad weather numerous times, most perilously around the 600-mile wide Typhoon Marge, and Libya when they were denied access to the country's airspace in response to the American bombing of Libya earlier that year. With that in mind, I'm not sure why they hadn't planned to fly around Libya in the first place. In front of 55,000 spectators and a large press contingent, including 23 live feeds breaking into scheduled broadcasting across Europe and North America, the plane safely came back to Earth, touching down at 8.06 am at the same airfield almost exactly nine days after takeoff. The average speed of the flight was 116 miles per hour, about a fifth the speed of modern commercial airliners. At touchdown, there were only 106 pounds of fuel remaining in the tanks, less than 2% the fuel they had to take off. The flight was the first successful aerial non-stop, non-refueled circumnavigation of the Earth that included two passes over the equator, as opposed to just circling the North or South Pole in a few minutes. In the 36 years since, this feat has only been accomplished one more time by Steve Fawcett in the Global Flyer, designed by the same man as the Voyager. Number 2 – The LTV-XC-142 Kind of a mouthful. Planes are great because they can go far and fast while carrying a lot of cargo, and helicopters are great because they can take off and land with very little space and without having a dedicated airstrip. But what if you could combine all of these traits into one plane? Well, meet the XC-142. The 142 was a tilt-wing experimental aircraft designed to investigate short takeoff and landing transports. Its wings could turn up to 90 degrees relative to the ground, so it could take off and land vertically while being able to achieve the faster speeds and larger cargo holes of a traditional plane. In service, it would carry 32 equipped troops or 8,000 pounds of cargo at a max speed of 400 miles per hour. The 142 first flew in September of 1964, and a few months later it crossed the Atlantic in normal flight while taking off and landing vertically. But while initial testing proved promising, problems would start piling up. During continued testing, the aircraft's crosslink drive shaft, the mechanism that allowed the plane wings to tilt, proved to be its Achilles' heel. The shaft resulted in excessive vibration, wing flexing, and difficulty operating the plane. And one major problem found in the aircraft was an instability between wing angles of 35 and 80 degrees, usually encountered during takeoff and landing. And new propellers designed especially for the XC142 proved to generate less thrust than expected. And as these problems piled up, the Air Force continually requested changes to the plane's design until the program was cancelled altogether. After that, the one surviving aircraft of the five originally built was handed over to NASA for testing and now sits on display at the U.S. Air Force's National Museum at Wright Patterson Air Force Base near Dayton, Ohio. Although this wouldn't be the death of VTOL aircraft, the first widely successful one came just a few years later in 1969 with the introduction of the British Harrier Jumbo Jet, which saw extensive use in the Falkland Wars and is still in service to this day, making it one of the most successful and most famous VTOL planes ever developed. And the U.S. didn't abandon the idea of VTOL aircraft altogether. Both the V-22 Osprey, first introduced in 2007, and the new F-35B stealth fighter have VTOL capabilities. Lastly, the Grumian X-29. The Grumian X-29 was an American experimental aircraft that tested a forward swept wing for NASA and the U.S. Air Force from 1984 to 1991. It was part of a quest to build the ultimate fighter jet by taking advantage of its inherent instability that would allow it to outmaneuver any enemy fighter. The aerodynamic instability of the X-29's airframe required the use of computerized fly-by-wire, which made corrections to the flight path 40 times a second to control the plane. The engineers concluded that if all the flight computers failed, aerodynamic forces would have destroyed the plane before the pilot even had a chance to eject. Planes with forward swept wings, which are angled in the opposite direction of conventional wings, are rare, but the X-29 wasn't the first to employ them. The German Junker Bombers from the Second World War were the first successful prototypes with this design, and the man who designed them would later create the Hansa HBF-320, a small business jet with forward swept wings that took to the skies in 1964. To this day, they're the only commercial aircraft to have ever employed forward swept wings, and a few still fly to this day. In the Hansa Jet, the wings were swept forward to allow them to be mounted further back along the plane's body, creating more space for passengers and an otherwise cramped aircraft. But whereas the Hansa Jet's wings were swept forward by just a few degrees, the X-29's were swept forward by 33. This put such immense forces on the wings, a new advanced composite had to be specially designed for them to keep the wings from being ripped off by the aerodynamic forces. The X-29's unique design led to another interesting effect. Have you ever seen those small flaps that go up and down on the wings of a plane, often around takeoff and landing? Well, those are called ailerons, and they're a crucial component to controlling a plane. When a normal plane goes into a stall, a loss of lift that can lead to a crash, the ailerons are usually the first thing to stop working, because stalls tend to start at the wing tip and move inward, due to the way the air flows over a wing. This loss of use of the ailerons leads to a loss of control in an already dangerous situation. But with forward swept wings like the ones on the X-29, air flow is forced in the opposite direction, moving inwards towards the fuselage. This causes stalls to start closer to the main body of the plane, leaving the ailerons functional for longer and giving pilots much needed control. While the plane was being developed, this maneuverability was believed to be essential for fighter superiority, because if you're playing stalls before enemies, you can easily be shot out of the sky. The X-29s were flown in 422 research missions between 1984 and 1992, but in the end, as stealth became more important than maneuverability, the X-29 was resigned to history. And since then, forward swept wings have also been made obsolete by thrust vectoring, or the ability to physically move an engine to control the direction of its thrust, ensuring maneuverability even in case of a stall. Well, I hope you liked learning a bit more about these unusual planes. If you liked the video, be sure to subscribe. And remember, there's always more to learn.