Aircraft have different ways to take off and land. Conventional airplanes accelerate along the ground until reaching a speed that is sufficient for the airplane to takeoff and climb at a safe speed. Some airplanes can take off at low speed, this being a short takeoff. Some aircraft such as helicopters and Harrier jump jets can take off and land vertically. Rockets also usually take off vertically, but some designs can land horizontally.
Takeoff is the phase of flight in which an aircraft goes through a transition from moving along the ground (taxiing) to flying in the air, usually starting on a runway. For balloons, helicopters and some specialized fixed-wing aircraft (VTOL aircraft such as the Harrier), no runway is needed. Takeoff is the opposite of landing.
Landing is the last part of a flight, where a flying aircraft or spacecraft (or animals) returns to the ground. When the flying object returns to water, the process is called alighting, although it is commonly called "landing" and "touchdown" as well. A normal aircraft flight would include several parts of flight including taxi, takeoff, climb, cruise, descent and landing.
RTOL aircraft require shorter runways than conventional types, typically 3,500 feet (1,100 m) to 4,500 feet (1,400 m). [1] [2]
STOL is an acronym for short take-off and landing, aircraft with very short runway requirements, typically between 2,000 feet (610 m) to 3,500 feet (1,100 m). [2]
CATOBAR (catapult assisted takeoff but arrested recovery) is a system used for the launch and recovery of aircraft from the deck of an aircraft carrier. Under this technique, aircraft are launched using a catapult and land on the ship (the recovery phase) using arrestor wires.
Although this system is more costly than alternative methods, it provides greater flexibility in carrier operations, since it allows the vessel to support conventional aircraft. Alternate methods of launch and recovery can only use aircraft with STOVL or STOBAR capability.
STOBAR (Short Take Off But Arrested Recovery) is a system used for the launch and recovery of aircraft from the deck of an aircraft carrier, combining elements of both STOVL (Short Take-Off and Vertical Landing) and CATOBAR (Catapult Assisted Take-Off But Arrested Recovery).
Horizontal takeoff, horizontal landing (HTHL) — is the mode of operation for the first private commercial spaceplane, the two-stage-to-space Scaled Composites Tier One from the Ansari X-Prize SpaceShipOne/WhiteKnightOne combination. It is also used for the upcoming Tier 1b SpaceShipTwo/WhiteKnightTwo combination. A prominent example of its use was the North American X-15 program. In these examples the space craft are carried to altitude on a "mother ship" before launch. The failed proposals for NASA Space Shuttle replacements, Rockwell X-30 NASP used this mode of operation but were conceived as single stage to orbit.
The Lynx rocketplane was a suborbital HTHL spaceplane developed by XCOR Aerospace that was slated to begin atmospheric flight testing in late 2011. [3] However, after numerous delays, XCOR Aerospace went bankrupt in 2017 without finishing a prototype. [4]
Reaction Engines Skylon, a design descendant of the 1980s British HOTOL ("Horizontal Take-Off and Landing") design project, is an HTHL spaceplane currently in the early stages of development in the United Kingdom. [5]
Both the Lynx rocketplane and SpaceShipTwo have been proffered to NASA to carry suborbital research payloads in response to NASA's suborbital reusable launch vehicle (sRLV) solicitation under the NASA Flight Operations Program. [6]
An early example was the 1960s Northrop HL-10 atmospheric test aircraft where the HL stands for "Horizontal Lander". [7]
Different terms are used for takeoff and landing depending on the source of thrust used. VTVL uses rockets, whereas VTOL uses air, propelled via some kind of rotor system.
Vertical Take-Off and Landing (VTOL) aircraft includes fixed-wing aircraft that can hover, take off and land vertically as well as helicopters and other aircraft with powered rotors, such as tiltrotors. [8] [9] [10] [11] The terminology for spacecraft and rockets is VTVL (vertical takeoff with vertical landing). [12] Some VTOL aircraft can operate in other modes as well, such as CTOL (conventional take-off and landing), STOL (short take-off and landing), and/or STOVL (short take-off and vertical landing). Others, such as some helicopters, can only operate by VTOL, due to the aircraft lacking landing gear that can handle horizontal motion. VTOL is a subset of V/STOL (vertical and/or short take-off and landing).
Besides the ubiquitous helicopter, there are currently two types of VTOL aircraft in military service: craft using a tiltrotor, such as the Bell Boeing V-22 Osprey, and aircraft using directed jet thrust such as the Harrier family. 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).
Vertical takeoff, vertical landing (VTVL) is a form of takeoff and landing for rockets. Multiple VTVL craft have flown. The most widely known and commercially successful VTVL rocket is SpaceX's Falcon 9 first stage.
VTVL technologies were developed substantially with small rockets after 2000, in part due to incentive prize competitions like the Lunar Lander Challenge. Successful small VTVL rockets were developed by Masten Space Systems, Armadillo Aerospace, and others.
In aviation the term VTOHL ("Vertical Take-Off and Horizontal Landing") as well as several VTOHL aviation-specific subtypes: VTOCL, VTOSL, VTOBAR exist.
The zero length launch system or zero length take-off system (ZLL, ZLTO, ZEL, ZELL) was a system whereby jet fighters and attack aircraft were intended to be placed upon rockets attached to mobile launch platforms. Most zero length launch experiments took place in the 1950s, during the Cold War.
Vertical takeoff, horizontal landing (VTHL) is the mode of operation for all current and formerly operational orbital spaceplanes, such as the Boeing X-37, the NASA Space Shuttle, the 1988 Soviet Buran space shuttle, and the PRC CSSHQ/Shenlong. For launch vehicles an advantage of VTHL over HTHL is that the wing can be smaller, since it only has to carry the landing weight of the vehicle, rather than the takeoff weight. [13]
There have been several VTHL proposals that never flew, including the circa-1960 USAF Boeing X-20 Dyna-Soar project, NASA Space Shuttle proposed replacements, Lockheed Martin X-33, and VentureStar. The 1990s NASA concept spaceplane, the HL-20 Personnel Launch System (HL stands for "Horizontal Lander"), was VTHL, as was a circa-2003 derivative of the HL-20, the Orbital Space Plane concept.
As of March 2011 [update] , two VTHL commercial spaceplanes were in various stages of proposal/development, both successors to the HL-20 design. The Sierra Nevada Corporation Dream Chaser follows the outer mold line of the earlier HL-20. The circa-2011 proposed Orbital Sciences Corporation Prometheus was a blended lifting body spaceplane that followed the outer mold line of the circa-2003 Orbital Space Plane, itself a derivative of the HL-20; however, Prometheus did not receive any NASA contracts and Orbital has announced they will not pursue further development. [14]
German Aerospace Center studied reusable VTHL Liquid Fly-back Boosters from 1999. Design was intended to replace Ariane 5 solid rocket boosters. [15] The U.S. government-funded, US$ 250,000,000, Reusable Booster System program, initiated by the USAF in 2010, [16] had specified a high-level requirement that the design be VTHL, [17] but the funding was discontinued after 2012. [18]
In 2017 DARPA selected a VTHL design for XS-1.
Few airplanes can operate with conventional takeoff and vertical landing (and its subtypes STOVL, CATOVL) as the F-35B.
Horizontal takeoff and vertical landing (HTVL) in spaceflight has not been used, but has been proposed for some systems that use a two-stage to orbit launch system with a plane based first stage, and a capsule return vehicle. One of the few HTVL concept vehicles is the 1960s concept spacecraft Hyperion SSTO, designed by Philip Bono. [19]
Vehicles use more than one mode also exist.
Vertical and/or short take-off and landing (V/STOL) aircraft that are able to take off or land vertically or on short runways. Vertical takeoff and landing (VTOL) includes craft that do not require runways at all. Generally, a V/STOL aircraft needs to be able to hover; helicopters are not typically considered under the V/STOL classification.
A rolling takeoff, sometimes with a ramp (ski-jump), reduces the amount of thrust required to lift an aircraft from the ground (compared with vertical takeoff), and hence increases the payload and range that can be achieved for a given thrust. For instance, the Harrier is incapable of taking off vertically with a full weapons and fuel load. Hence V/STOL aircraft generally use a runway if it is available. I.e. Short Take-Off and Vertical Landing (STOVL) or Conventional Take-off and Landing (CTOL) operation is preferred to VTOL operation.
V/STOL was developed to allow fast jets to be operated from clearings in forests, from very short runways, and from small aircraft carriers that would previously only have been able to carry helicopters.
The main advantage of V/STOL aircraft is closer basing to the enemy, which reduces response time and tanker support requirements. In the case of the Falklands War, it also permitted high performance fighter air cover and ground attack without a large aircraft carrier equipped with a catapult.
The latest V/STOL aircraft is the F-35B, which entered service in 2015. [20]
A short take-off and vertical landing aircraft is a fixed-wing aircraft that is able to take off from a short runway and land vertically. The formal NATO definition is:
A Short Take-Off and Vertical Landing aircraft is a fixed-wing aircraft capable of clearing a 15 m obstacle within 450 m of commencing take-off run, and capable of landing vertically.
A vertical take-off and landing (VTOL) aircraft is one that can take off and land vertically without relying on a runway. This classification can include a variety of types of aircraft including helicopters as well as thrust-vectoring fixed-wing aircraft and other hybrid aircraft with powered rotors such as cyclogyros/cyclocopters and gyrodynes.
Takeoff is the phase of flight in which an aerospace vehicle leaves the ground and becomes airborne. For aircraft traveling vertically, this is known as liftoff.
A lifting body is a fixed-wing aircraft or spacecraft configuration in which the body itself produces lift. In contrast to a flying wing, which is a wing with minimal or no conventional fuselage, a lifting body can be thought of as a fuselage with little or no conventional wing. Whereas a flying wing seeks to maximize cruise efficiency at subsonic speeds by eliminating non-lifting surfaces, lifting bodies generally minimize the drag and structure of a wing for subsonic, supersonic and hypersonic flight, or spacecraft re-entry. All of these flight regimes pose challenges for proper flight safety.
Human spaceflight programs have been conducted, started, or planned by multiple countries and companies. Until the 21st century, human spaceflight programs were sponsored exclusively by governments, through either the military or civilian space agencies. With the launch of the privately funded SpaceShipOne in 2004, a new category of human spaceflight programs – commercial human spaceflight – arrived. By the end of 2022, three countries and one private company (SpaceX) had successfully launched humans to Earth orbit, and two private companies had launched humans on a suborbital trajectory.
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. Vertical takeoff and landing (VTOL) aircraft are a subset of V/STOL craft that do not require runways at all. Generally, a V/STOL aircraft needs to be able to hover. Helicopters are not considered under the V/STOL classification as the classification is only used for aeroplanes, aircraft that achieve lift (force) in forward flight by planing the air, thereby achieving speed and fuel efficiency that is typically greater than the capability of helicopters.
A reusable launch vehicle has parts that can be recovered and reflown, while carrying payloads from the surface to outer space. Rocket stages are the most common launch vehicle parts aimed for reuse. Smaller parts such as rocket engines and boosters can also be reused, though reusable spacecraft may be launched on top of an expendable launch vehicle. Reusable launch vehicles do not need to make these parts for each launch, therefore reducing its launch cost significantly. However, these benefits are diminished by the cost of recovery and refurbishment.
A spaceplane is a vehicle that can fly and glide like an aircraft in Earth's atmosphere and maneuver like a spacecraft in outer space. To do so, spaceplanes must incorporate features of both aircraft and spacecraft. Orbital spaceplanes tend to be more similar to conventional spacecraft, while sub-orbital spaceplanes tend to be more similar to fixed-wing aircraft. All spaceplanes to date have been rocket-powered for takeoff and climb, but have then landed as unpowered gliders.
The Lockheed Martin X-33 was a proposed uncrewed, sub-scale technology demonstrator suborbital spaceplane that was developed for a period in the 1990s. The X-33 was a technology demonstrator for the VentureStar orbital spaceplane, which was planned to be a next-generation, commercially operated reusable launch vehicle. The X-33 would flight-test a range of technologies that NASA believed it needed for single-stage-to-orbit reusable launch vehicles, such as metallic thermal protection systems, composite cryogenic fuel tanks for liquid hydrogen, the aerospike engine, autonomous (uncrewed) flight control, rapid flight turn-around times through streamlined operations, and its lifting body aerodynamics.
The DC-X, short for Delta Clipper or Delta Clipper Experimental, was an uncrewed prototype of a reusable single-stage-to-orbit launch vehicle built by McDonnell Douglas in conjunction with the United States Department of Defense's Strategic Defense Initiative Organization (SDIO) from 1991 to 1993. Starting 1994 until 1995, testing continued through funding of the US civil space agency NASA. In 1996, the DC-X technology was completely transferred to NASA, which upgraded the design for improved performance to create the DC-XA. After a test flight of DC-XA in 1996 resulted in a fire, the project was canceled. Despite its cancellation, the program inspired later reusable launch systems. Michael D. Griffin has since praised the program as "government R&D at its finest."
A tiltwing aircraft features a wing that is horizontal for conventional forward flight and rotates up for vertical takeoff and landing. It is similar to the tiltrotor design where only the propeller and engine rotate. Tiltwing aircraft are typically fully capable of VTOL operations.
Hopper was a proposed European Space Agency (ESA) orbital spaceplane and reusable launch vehicle. The Hopper was a FESTIP system study design.
Philip Bono was a Douglas Aircraft Company engineer. He was a pioneer of reusable vertical landing single-stage to orbit launch vehicles. As a visionary designer, he is credited with inventing the first version of a recoverable single-stage spacecraft booster, and his contributions influenced spacecraft design.
The HL-20 Personnel Launch System was a NASA spaceplane concept for crewed orbital missions studied by NASA's Langley Research Center around 1990. It was envisaged as a lifting body re-entry vehicle similar to the Soviet BOR-4 spaceplane design. Its stated goals were to achieve low operational costs, improved flight safety, and a possibility of landing on conventional runways. No flight hardware was built.
Vertical takeoff, vertical landing (VTVL) is a form of takeoff and landing for rockets. Multiple VTVL craft have flown. The most successful VTVL vehicle was the Apollo Lunar Module which delivered the first humans to the Moon. Building on the decades of development, SpaceX utilised the VTVL concept for its flagship Falcon 9 first stage, which has delivered over three hundred successful powered landings so far.
A powered lift aircraft takes off and lands vertically under engine power but uses a fixed wing for horizontal flight. Like helicopters, these aircraft do not need a long runway to take off and land, but they have a speed and performance similar to standard fixed-wing aircraft in combat or other situations.
Science Realm is a United States Government project with the aim of creating a vertical-takeoff horizontal-landing (VTOHL) single-stage-to-orbit (SSTO) craft, the term is also associated with the software this project uses to simulate takeoff and landing.
Prometheus was a proposed crewed vertical-takeoff, horizontal-landing (VTHL) lifting body spaceplane concept put forward by Orbital Sciences Corporation in late 2010 as part of the second phase of NASA's Commercial Crew Development (CCDev) program.
The DARPA XS-1 was an experimental spaceplane/booster with the planned capability to deliver small satellites into orbit for the U.S. Military. It was reported to be designed to be reusable as frequently as once a day, with a stated goal of doing so for 10 days straight. The XS-1 was intended to directly replace the first stage of a multistage rocket by taking off vertically and flying to hypersonic speed and high suborbital altitude, enabling one or more expendable upper stages to separate and deploy a payload into low Earth orbit. The XS-1 would then return to Earth, where it could ostensibly be serviced fast enough to repeat the process at least once every 24 hours.
Bristol Spaceplanes (BSP) is a British aerospace company based in Bristol, England, who has designed a number of spaceplanes with sub-orbital and orbital capabilities. The company's stated goal is "to realise low-cost access to space", primarily through reusable launch vehicles, claiming the cost of human space travel has the potential to be reduced by a factor of 1,000.
work is coming along nicely on building the first test flight vehicle which the company hopes to fly by the end of the year.
Lynx: Type: HTHL / Piloted ... SpaceShipTwo: Type: HTHL / Piloted
CEO Dave Thompson said ... "I don't, at this time, anticipate that we'll continue to pursue our own project in that race. We'll watch it and if an opportunity develops we may reconsider. But at this point, I would not anticipate a lot of activity on our part in the commercial crew market."
Officials anticipate awarding up to three contracts for the project, where winners would compete for individual tasks of experiments and demonstrations that address technology, processes and other attributes of a reusable booster system, or RBS. Air Force officials envision an RBS that includes a reusable rocket and an expendable upper stage rocket. The reusable rocket would be launched vertically and return, landing aircraft style on a runway, after carrying the space craft to a point where the expendable rocket could take over.
The 'Hyperion' vehicle was truly remarkable since it would have been launched horizontally and landed vertically (HTVL) — an extremely rare combination. The payload capability was 110 passengers or 18t of cargo.