Original vintage 1960s Bell Helicopter advert for the company's VTOL (a subset of V/STOL) airframes - what's a VTOL? Think the iconic Bell V-22 Osprey, but half a century older.
"Helicopter and airplane characteristics are efficiently blended in a highly versatile vehicle with multi-service mission potential. Speed is increased by over 100% in comparison with contemporary helicopters. The effect is global self-deployment capability and a corresponding increase in radius of action on all traditional military helicopter missions, which include reconnaissance, tactical troop lift, re-supply, medical evacuation and rescue."
Dimensions: Approx. 16.50 inches wide by 11 inches high - this is a two page advert
A vertical and/or short take-off and landing (V/STOL) aircraft is an airplane able to take off or land vertically or on short runways, with vertical takeoff and landing (VTOL) aircraft as a subset of V/STOL craft that do not require runways at all. Helicopters are not considered under the V/STOL classification as the classification is only used for airplanes, aircraft that achieve lift in forward flight by planing the air, thereby achieving speed and fuel efficiency that is typically greater than the capability of helicopters.
Vertical take-off and landing (VTOL) is a subset of V/STOL – this classification can include a variety of types of aircraft as well as thrust-vectoring fixed-wing aircraft and other hybrid aircraft with powered rotors such as cyclogyros and gyrodynes.
The idea of vertical flight has been around for thousands of years, and sketches for a VTOL (helicopter) show up in Leonardo da Vinci's sketch book. Manned VTOL aircraft, in the form of primitive helicopters, first flew in 1907, but would take until after World War Two to be perfected.
In addition to helicopter development, many approaches have been tried to develop practical aircraft with vertical take-off and landing capabilities, including Henry Berliner's 1922–1925 experimental horizontal-rotor fixed-wing aircraft, and Nikola Tesla's 1928 patent, and George Lehberger's 1930 patent for relatively impractical VTOL fixed wing airplanes with tilting engines.
In the late 1930s, British aircraft designer Leslie Everett Baynes was issued a patent for the Baynes Heliplane, another tiltrotor aircraft. In 1941, German designer Heinrich Focke's began work on the Focke-Achgelis Fa 269, which had two rotors that tilted downward for vertical takeoff, but wartime bombing halted development.[10]
Some VTOL aircraft can operate in other modes as well, such as CTOL (conventional take-off and landing), STOL (short take-off and landing), or STOVL (short take-off and vertical landing). Others, such as some helicopters, can only operate as VTOL, due to the aircraft's lack of landing gear that can handle taxiing. Some lighter-than-air aircraft also qualify as VTOL aircraft, as they can hover, take off and land with vertical approach/departure profiles.
NASA has flown other VTOL craft such as the Bell XV-15 research craft (1977), as have the Soviet Navy and Luftwaffe. Sikorsky tested an aircraft dubbed the X-Wing, which took off in the manner of a helicopter. The rotors would become stationary in mid-flight, and function as wings, providing lift in addition to the static wings, with the Boeing X-50 is a Canard Rotor/Wing prototype that utilizes a similar concept.
Besides the ubiquitous helicopters, there are currently two types of VTOL aircraft in military service: tiltrotor aircraft, such as the Bell Boeing V-22 Osprey, and thrust-vectoring airplanes, such as the Harrier family and new F-35B Lightning II Joint Strike Fighter (JSF). In the civilian sector, currently only helicopters are in general use (some other types of commercial VTOL aircraft have been proposed and are under development as of 2017). Generally speaking, VTOL aircraft capable of STOVL use the latter wherever possible, since it typically significantly increases takeoff weight, range, or payload compared to pure VTOL.
Presently, electric vertical takeoff and landing aircraft, or eVTOLs, are being developed along with more autonomous flight control technologies and mobility-as-a-service (MaaS) to enable advanced air mobility (AAM), that could include on-demand air taxi services, regional air mobility, freight delivery, and personal air vehicles (PAVs).
With eVTOLs, there exists an emerging demand for new aerial vehicles capable of facilitating greener and quieter flights within the domain of Advanced Air Mobility and Urban Air Mobility. Electric and hybrid propulsion systems (EHPS) have also the potential of lowering the operating costs of aircraft.
EVTOL designers include legacy manufacturers such as Airbus, Boeing, Embraer, Honda, Hyundai, LEO Flight and Toyota, as well as several start-up companies, including Archer Aviation, Beta Technologies, EHang, Joby Aviation, Overair, and Volocopter. This ecosystem of firms developing eVTOLs includes the spin-off of legacy aircraft manufacturers, such as Eve Air Mobility, which emerged from the EmbraerX division of Embraer, as well as partnerships, such as Wisk Aero, which was launched as a joint venture between Boeing and Larry Page's Kitty Hawk.
In April 2020, the USAF announced $25 million-worth funding of eVTOL projects for development in 2021; during the same year, the United States Air Force (USAF) held a demonstration flight of an electric vertical take-off and landing aircraft at Camp Mabry in Austin, Texas marking the first time a manned eVTOL aircraft took flight under USAF Agility Prime program.
