Airfoils (cross-section of wing, directly determines lift properties):
Sweep/AR/Planform/Dihedral/Twist
Wings with high sweep are often indicative of supersonic flight capabilities. Sweeping the wings back helps tuck them inside the shock wave to reduce drag at supersonic speeds.
Wings with high aspect ratio are less maneuverable, but generally work well as gliders.
Elliptical wing planforms have better aerodynamic performance than straight/rectangular wings.
Wing twist helps prevent the full wing from stalling at a single instance. e.g. If the inboard section near the root (where the wing attaches to the fuselage) is at a higher alpha than the outboard section near the tip, then when you pitch up the root will reach its stall angle sooner than the tip. In that case the outboard region (where the ailerons are) will still have attached flow so you can still use the ailerons to provide roll control.
Engine Types
There are 3 major engine types used in aircraft: gas-driven propeller systems, electrically-driven (battery powered) propeller systems, and jet engines (including turbojets/turbofans/turboprops/ramjets). Several of these are shown below. They have different applications and efficiency levels. They are discussed in detail in Flight Science/Engineering.
Additionally, with propeller aircraft there are different styles of how the thrust is applied. Puller (aka “tractor”) systems have propellers in the front to pull the aircraft forward. Pusher systems have propellers in the back to push the aircraft forward.
Puller/Tractor system (left) and pusher system (right).
Tail (Empennage) Styles: An aircraft with no tail is sometimes referred to as a “flying wing“. The B2 (shown below) is an example. Here the wings are swept back so the ailerons double as elevators, and are thus called “elevons”. This is different from a “delta wing” where the wing and horizontal tail are one (see Space Shuttle below). An aircraft with a tail in front of the wing is referred to as a “Canard” configuration. The X-29 (shown below) is an example.
Miscellaneous Aircraft Features
Flaps and Slats are High-Lift Devices built into the wing that can be deployed to alter the airfoil shape and adjust the lift characteristics (CL) of the wing. These are often used during takeoff and landing to increase lift when the vehicle is traveling at its slowest speeds (where the wing would ordinarily stall). The ailerons can also be used for this purpose by actuating downwards in-tandem to increase the wing camber. (They are then sometimes humorously referred to as “flaperons”.) Various types of these devices are shown here, which each have different characteristics. Static Wicks (far left) are placed along the trailing edges of the wings to disperse static electricity that builds up on the aircraft from friction with the air. The pods underneath the wing (middle-left) are flap track fairings that house the mechanisms used to drive the wing flaps. The panels on top of the wing (middle-right) are spoilers (or “lift dumpers”) used during landing to reduce lift and speed (like brakes). Miscellaneous pods mounted elsewhere on the wing (far right) may be used for various purposes (housing radar equipment, weapons systems, fuel tanks, mass balance weights, etc).Ice can form on the leading edge of the wing in flight, which alters the airfoil shape and can degrade the aerodynamic characteristics of the wing; de-icing boots (far left) are installed on the leading edge and are slightly inflated to break off the ice. Fringed chevron pedals (middle-left) are used on some engine nacelles; they can be curled inward to help mix the exhaust with the freestream to reduce engine noise (modeled after the fringed trailing edge of an owl’s wing). Pitot tubes (middle-right) are used to measure the airspeed of the aircraft in-flight. Anti-shock bodies (aka Whitcomb Bodies or Kucheman Carrots) on the upper surface of the wing (far right) are used to reduce shock wave drag that can form during transonic flight.Winglets are surfaces mounted on the wingtips which are used to control the formation of wingtip vortices which degrade the aerodynamic performance of the wing. There are various types of the winglets as shown here, with varying characteristics.
Bio & Bio-inspired Aircraft
In nature we see a large variety of flying animals. Birds come in many shapes and sizes; some with long wings made for soaring (like vultures), some with small wings made for tight aerial manuevers (swallows), some made for aerial hunting (falcons/eagles/owls), some aquatic birds (ducks/gulls/pelicans), and some even capable of hovering (hummingbirds). There are also bats and flying foxes, which are members of the mammal family. There are many flying insects as well, as well as flying squirrels and flying fish (though these really just glide). Here are some interesting facts concerning the natural flyers:
Albatross have the biggest wingspan (~12 feet).
Peregrine Falcons can achieve the fastest speeds (241mph).
Owls can fly so quietly you probably wouldn’t hear them. This is due to fringed trailing edges on their wings which minimize the air disturbance that causes the “wooshing” sound on other birds. This helps them maximize stealth as aerial hunters.
Bio-inspired aircraft are those that seek to mimic flight mechanisms seen in nature. The earliest flight pioneers sought to mimic bird-flight by flapping feathered-devices strapped on their arms. While this did not succeed, there are flapping-wing aircraft, known as ornithopters, and other modern bio-mimetic aircraft.
Various bio-inspired flying robots created by Festo.
Traditional Aircraft
FighterAircraft
Fighter aircraft are often designed to be aerodynamically unstable in order to achieve high-manueverability. They require fly-by-wire mechanisms that automatically adjust the control surfaces to keep the aircraft stable so the pilot can control it. Lockheed Martin is a major designer of American fighter aircraft.
The C-130 Hercules (left) and Supper Guppy (right) are used to carry heavy cargo.
BomberAircraft
Bomber aircraft are used to transport and drop bombs for military offense purposes. The B-29 Enola Gay dropped the first atomic bomb on Japan in WWII.
The B-52 Stratofortress (left) and Avro 679 Manchester (right).
Private/Business Jets
These are small aircraft used for private transportation purposes. Gulfstream, Embraer, Bombardier, Learjet are some of the major suppliers. These often involve luxury interiors.
General Aviation Aircraft
These are very small airplanes that are just above the ultra-light category. They are typically 2-seaters, used for personal travel of small distances or for training new pilots. Cessna is one of the main suppliers of this category of aircraft.
Jumbo Jets
These aircraft are designed to carry large numbers of passengers long distances. Boeing and Airbus are major suppliers. These aircraft are used by major airline companies like Delta, United, Southwest, American, etc.
Airbus A380 (left) can carry up to 853 passengers! Boeing 787 (right).
Stealth Aircraft
These aircraft are designed with special geometries that are hard to detect on radar (the Have Blue appeared roughly the size of a marble on radar; bats would crash into it because their echo-location wouldn’t detect it). This technology was pioneered by Lockheed’s Skunkworks department, which operated in the 1950s and 60s under extreme secrecy to provide the U.S. government with military technologies that would outmatch enemy countries.
Have Blue (left), F-117 Nighthawk (center; fighter), B-2 Spirit (right; bomber). (The B-2 is an example of a flying wing; i.e. no tail.)
Reconnaissance Aircraft
These are used by military organizations to monitor ground activity from above.
The E-2C Hawkeye (left) carries a large radar dish for relaying/detecting communication signals. The SR-71 Blackbird (center) flies at high altitudes (80k feet) around Mach 3. The MQ-9 Reaper Drone (right) is an unmanned aerial vehicle (UAV) controlled remotely.
Rotorcraft
Rotorcraft are different than fixed-wing aircraft. Rotorcraft use long rotor blades (basically long/thin wings) that spin at high speeds to generate lift. The rotor blades can be tilted to pitch and roll the vehicle. Frequently helicopters also have tail rotors to provide yaw stabilization. Rotorcraft are capable of vertical takeoff and landing (VTOL), as well as hovering flight (flying in place). Traditional fixed-wing aircraft cannot do this. Toy quadcopters are also examples of rotorcraft, as well as gyro-planes/compound-aircraft (which have rotors and wings.)
Blackhawk (left) is used for military operations. Life-Flight Helicopters are used to provide emergency medical transportation for people in critical condition. The Chinook (right) has two rotors and is also used for military transportation purposes.
Gyroplanes, also called Compound Aircraft.
Space Shuttle
The Space Shuttle is an example of an air- & space-craft. The Shuttle (also known as the Orbiter; STS series) typically launched vertically while attached to Solid State Booster rockets. In other configurations the Shuttle could deploy from atop a jumbo jet called the Shuttle Carrier Aircraft (a modified Boeing 747). The Shuttle would fly into space, re-enter the atmosphere using the heat-shield on the Shuttle underside and glide down to a runway using the wings and vertical stabilizer for control. The Shuttle was a NASA vehicle that flew during the 1990s. It was used to take astronauts into low-earth orbit (LEO) where they constructed the International Space Station (ISS). (The Shuttle is an example of a Delta-Wing.)
SupersonicAircraft
These aircraft are designed with special airfoils and extremely thin wings that allow them to break the speed of sound, also known as breaking the “sound barrier” (formerly thought to be an actual physical limit based on the immense increase in drag that occurs as you approach this speed). The speed of sound is also called Mach 1, and it the speed that sound waves travel through the atmosphere. This speed is a function of atmospheric temperature/density, which vary with altitude.
The X-1 (left) was piloted by Chuck Yeager and was the first aircraft to reach the speed of sound (Mach 1). The X-15 (center) was the first hypersonic aircraft; i.e. the first to Mach 5. The Concorde (right) was a supersonic public transportation aircraft that operated in the 1980s and 90s. (The Concorde is an example of a Delta-Wing.)
Gliders
These are typically unpowered aircraft (no engines/batteries) meaning they can only perform unpowered flight (gliding). They are often towed into the air by a powered aircraft and released, at which point they glide down gently. They cannot stay aloft very long without a thrust source, and so require wind or thermal updrafts to regain altitude. The characteristic long aspect ratio wings help provide lift even at low speeds.
VTOL Aircraft
These are fixed-wing aircraft capable of vertical takeoff and landing (VTOL). Vertical takeoff generally consumes more power than horizontal takeoff because the thrust source has to overcome the full weight of the vehicle, rather than just the drag as in horizontal flight. Vertical-to-horizontal flight transition is difficult from an aerodynamic perspective and is the focus of a lot of research for personal air vehicles. There are different mechanisms for vertical-to-horizontal transition including tilt-rotor, tilt-wing, and tail-sitting.
Left to right: V-22 Osprey (tilt-rotor); Harrier (tilt-engine); XFY-1 Pogo (tail-sitter); NASA Greased Lightning (tilt-wing). (The F-35 (not shown) can also perform VTOL similar to the Harrier.)
ElectricAircraft
These are electrically-powered aircraft that use batteries of hydrogen-cells which provide electric current that turns a motor connected to a propeller to provide thrust. This is different from traditional fuel-based aircraft that use gas/kerosene-combustion engines to turn the propeller shaft. There are also hybrid aircraft that have electric and fuel-based power sources.
Pipistrel (left) is the first certified electric plane. Solar Impulse (center) is a fully solar-powered plane and the first of its kind to fly around the entire world on only solar power. X-57 is a distributed-electric aircraft that has numerous electric propellers distributed across the wing.
Amphibious Aircraft
These are aircraft that takeoff and land using the surface of a body of water as the runway. Some of these are even designed to suck-up and store water on board that can then be dropped from the air to help with firefighting efforts.
Dual Wing Aircraft
These aircraft have two wing surfaces; twice the wing surface yields (theoretically) twice the lift.
A bi-plane (left) and a tandem-wing (right). In some cases a tandem-wing does not even need a horizontal tail.
Variable Sweep Aircraft (Swing Sweep)
Some aircraft have special actuators that allow the wings to fold into a delta-wing configuration for supersonic flight, or fold out into a more traditional configuration for slower flight.
The F-14 Tomcat in both wing configurations.
MiG-27 (left) and Dassault Mirage G (right)
The AD-1 Oblique Wing Aircraft is another type of variable-sweep aircraft that has a continuous wing surface that rotates about a central pivot, causing one side of the wing to sweep forward and the other side to sweep backward while maintaining the same center of gravity.
Experimental/Non-Conventional
The bracketing aircraft are members of the Virgin Airlines/Galactic Family. The center image is an asymmetric aircraft (Rutan Boomerang). The left image is a twin-fuselage vehicle.A joined-wing/box-wing/closed-wing concept (left), blended wing-body (center), and forward-swept wing (right; X-29). The X-29 is an example of a canard aircraft (tail in front of wing).
Lifting Body Aircraft have little or no wings and generate their lift from the shape of the fuselage itself. M2-F1 (left), HL-10 (right).
These are additional examples of closed-wing (annular/ring-wing) aircraft wing no wingtips.Saucer/Disk Aircraft; Lenticular Re-entry Vehicle (left), Vought V173 Pancake (center), Avrocar (right).
The Goodyear Inflatoplane is a novel concept involving a flexible/inflatable wing surface; handy for portability purposes.
Homebuilt/Kit Planes
Many homebuilt kits are small in size. The ones shown here are particularly tiny, bordering on the size of RC aircraft. The Stits SA-2A Skybaby (far left), Starr Bumble Bee II (mid-left), Colombian Cri Cri (mid-right), and Rutan Long EZ (far right) have wingspans as small as 5.5 ft.
Missiles
Missiles are rocket-driven explosives used for military attack/defense purposes. They can be launched from land/sea/air. The Iron-Dome (far right) is an example of a defense mechanism that fires missiles to intercept incoming missiles.
Spacecraft
Scitus Flight is primarily dedicated to aircraft and manned air transportation, so we don’t include much information on spacecraft/space-travel, but spacecraft are certainly related, and generally perform some amount of atmospheric flight (which requires aerodynamic design considerations). Plus, they are plain awesome, so enjoy:
Rockets
From left-to-right: Saturn V (used to get the first astronauts to the Moon in the 1960s as part of the Apollo Program; Named “Five” because of its 5 individual stages or segments that make up the rocket), Space Shuttle (used to build the ISS), Space Launch System (underwent maiden flight in 2022 to return humans to the moon as part of the Artemis Program), SpaceX’s Falcon 9 (used to transport astronauts and cargo to/from the ISS), SpaceX Falcon 9 First Stage post-flight (these rockets can fly back and land themselves on barges in the ocean to be re-used), SpaceX’s Starship (heavy-lift rocket that will be used for interplanetary travel and space tourism).
Crew Capsule
The astronauts (crew) ride the rocket into space from inside the capsule which is located on the top of the rocket (the Shuttle is an exception). When they get into Earth orbit they are generally traveling >17000mph. During re-entry the Earth’s atmosphere provides drag to help them slow down, but the tremendous causes the air to heat up to extreme temperatures. The capsule is equipped with a heat shield that is used to dissipate the heat through a process known as ablation. Once they have slowed down, the capsule deploys parachutes that they use to descend to the water. The capsule then floats in the ocean and is picked up by a Navy military vessel and returned to land.
Miscellaneous Spacecraft
Left-to-right: The Hubble Space Telescope orbits Earth and is used to capture images of distant galaxies. Various types of satellites also orbit Earth, like GPS satellites to help you navigate, or satellites to provide tv signal, or the SpaceX Starlink satellites which will provide internet signal. The International Space Station is a science laboratory that orbits Earth and has been home to hundreds of astronauts since it was became operational in 2000. SpaceX’s Dragon capsule is shown docking with the ISS, bringing a new batch of astronauts for a 6-month stay on the station. The Lunar Lander and Lunar Rover were used by Apollo astronauts to land and travel around on the Moon.
Personal Air Vehicles
Personal Air Vehicles (PAVs) include a wide variety of flying devices that vary in scale and pilot interface. Many of these aircraft occupy a vehicle design-space that is relatively new, so laws regulating the operation of these vehicles are still in development. Based on the size, some of these would be classified (in the United States) as “ultralight” vehicles which do not require a pilot’s license to operate. (Note: There are still air-space restrictions governing where such vehicles can be flown.) For details on the definition/classification of ultralight vehicles, see: Ultralight aircraft (United States) – Wikipedia.)
Many of the larger PAVs fall into the “flying car” domain and are being developed to provide “air-taxi” services for urban air mobility. Some of the smaller PAVs are more in the “jetpack” arena in how they integrate onto the pilot’s body. Many PAV’s are VTOL designs that could takeoff/land on top of buildings or front-yards. Hundreds of these aircraft occupying city airspace as part of a continual public transportation mechanism poses various technical challenges. There will need to be advanced automated air traffic control systems to prevent in-air collisions, and advanced Hazard Detection/Navigation systems to perform emergency landings in congested environments. These designs also pose a considerable noise pollution concern, since the engines/motors on most aircraft are extremely loud. Furthermore, for such a technology to really take off it must gain public trust and societal/psychological normalization. NASA Langley and the FAA are working on developing the air traffic control infrastructure and aircraft certification requirements through the Advanced Air Mobility Program (AAM). The US Air Force has a similar program called AFWERX Agility Prime, which is focused on aiding the development of small VTOL aircraft. A few of the more mature PAVs are shown below. Hundreds of others can be found in the database at www.evtol.news. With so many vehicles surfacing in this market every few months, the consulting group SMG has put together the “Advanced Air Mobility Reality Index” (ARI) to help keep track of the leading vehicles in terms of tech-readiness, company-readiness, etc. (www.aamrealityindex.com).
Joby Aviation S4 (left), eHang (center), Hoversurf (right)Airbus (left), Lilium (center), Volocopter (right)Roadable aircraft are truly “flying cars”. These often utilize folding/retractable wings so they can fly or drive on roadways. The Klein Vision Aircar (left) and Terrafugia Transition (right) are 2 examples.
Alef is an electric flying car concept that received FAA certification in 2023. It is designed to transform from car to aircraft by rotating onto its side allowing propellers in the wheel wheels to act as thrusters, and the side paneling to serve as lifting wing surfaces. The cockpit will also pivot to keep the pilot/passengers upright.
Xpeng AeroHT’s Flying Car (left) and X2 PAV (right).
The Airbus/Italdesign Pop.Up is a modular drone/car hybrid concept that would swap wheels for propellers depending on where you needed to locomote.
The Sirius Jet (left) is a liquid hydrogen VTOL concept with embedded ducted jets, and the Ascendance Atea (right) is a fuel/battery hybrid design with embedded fans.
The Helix Pivotal takes off with vertically oriented propellers, which then rotate horizontally to provide lateral thrust.
The Pterodynamics Transwing has a unique wing-folding mechanism that offers a compact profile during vertical takeoff/landing and a larger wing area for passive lift and increased efficiency during cruise.
NASA Puffin – A tail-sitter. This is still in the design-phase.
electraFly
The Flying Kyxz Koncepto Milenya (left; similar to the Jetson Aero aircraft). Hoversurf Scorpion (right).
Hunter Kowald Hoverboard (left), similar to Omni Hoverboard (not shown); Colin Furze Bicopter Hoverbike (right)
The Opensky M-02J is a combo of a hang-glider and a jet aircraft, controlled by traditional control surfaces and pilot weight-shifting. This is an example of a prone-pilot aircraft in which the pilot’s body is parallel with the fuselage, rather than seated upright. (The Horten Glider, Beecraft Wee Bee, and original Wright Flyers are other examples of prone pilot configurations.)
The De Lackner HZ-1 Aerocycle (left) and Gen H-4 Helicopter (right) are two rotor-based PAVs.
Project Falcon is an electric ornithopter exoskeleton being designed by Douglas C. George. This vehicle is still in the design-phase but could enable humans to fly like the birds, perhaps the way it was depicted in this unrelated hoax video (emphasis: this video is not associated with Project Falcon and involves special effects rather than actual flight): Man Flies Like a Bird using Actual Wings – YouTube
The Boeing GoFly Competition is a contest that is encouraging small businesses/universities to develop personal aircraft for a cash prize. Various concepts from this contest are shown here.
Miscellaneous
Hang-gliders; unpowered (left), powered (right). Unpowered hang-gliders must launch from the top of a hill or catch thermal updrafts to generate lift. The pilot hangs below the wing and shifts his/her center of gravity using the control bar to steer the glider.
An ultra-light trike aircraft. Uses a hang-glider-esque wing and control bar, and includes a cockpit/seat and propeller for power.
Paramotor. (Without the motor it is just a “Paraglider”. If a paraglider is towed by a boat it is known as “Parasailing”. These parafoils are similar to parachutes but made for very different purposes.) To steer, the pilot pulls down on control cables that warp the parafoil and alter the airflow passing over it.
Parachutes are used for skydiving and spacecraft capsule re-entry/landing. Speed-parachuting involves special parafoils that enable aerial acrobatics and high-speed maneuvering.
Wingsuit – modeled after a flying squirrel. Wingsuit flyers are trained skydivers/base-jumpers.
The Archaeopteryx glider. (Check out this foot-launch video: https://www.youtube.com/watch?v=c0KzLeCm-Jw&t=11s )
The MacCready Gossamer Albatross is a human-powered plane. The pilot drives a pedal (like a bicycle) which turns the propellers to generate thrust. This vehicle crossed the English Channel in 1979.
A gyrocopter uses an unpowered rotor blade that develops lift by auto-rotating due to the air-flow generated by the independent (powered) horizontal thrust source.
Balloons “fly” via the principle of buoyancy. The gas inside the balloon (whether helium, hydrogen, or hot-air) is less-dense than the ambient air on the outside of the balloon. This causes the ambient air to push up on the balloon, causing it to rise. This is also how floating lanterns work.
A Blimp/Zeppelin/Airship/Derrigible utilizes a lighter-than-air gas (like hydrogen) to float like a balloon. These aircraft, however, are controllable/steerable. Hydrogen is very flammable which makes these aircraft, as they could explode if there is a spark onboard. The Hindenburg is an infamous example of this happening (see History of Flight).
The Airfish-8 is a Ground-Effect Vehicle (GEV) or Wing-In-Ground-Effect (WIG) Vehicle that flies a few feet above the surface of water by making use of the interaction of the wing-tip airflow interacting with the surface below.
A hovercraft rides on top of a thin layer of air that comes out from underneath the airbag. The air passes between the airbag and the ground, so the vehicle can glide along the surface of the ground (or over water) with minimal friction. It is similar to how a puck glides over the surface of an air-hockey table. It’s not exactly flying, but worth mentioning.
A cyclocopter/cyclogyro is an aircraft with multiple small wings/blades oriented horizontally that spin about a horizontal axis to create vertical lift. Russia’s Cyclocar is one example of a large-scale cyclocopter.
Kite-surfing (left), Wind-surfing (center), and Wing-surfing (right) are not “flight”, but they utilize a parafoil, sail, and handheld wing (respectively) to provide lift/thrust from the wind so the surfer can ride a board across the surface of the water.
A kite is a flying toy that requires a cable mounted at the center of lift in order to tow the kite into the sky and help it maintain controlled flight.
A frisbee is able to fly in a stable manner because of spin-stabilization. (Try throwing a frisbee without spin… it won’t go far.)
