Dive brakes or dive flaps are deployed to slow down an aircraft when in a dive. They often consist of a metal flap that is lowered against the air flow, thus creating drag and reducing dive speed. 
In the past, dive brakes were mostly used on dive bombers, which needed to dive very steeply, but without exceeding their red line speed, in order to drop their bombs accurately. The airbrakes or spoilers fitted to gliders often function both as landing aids, to adjust the approach angle, and to keep the aircraft's speed below its maximum permissible indicated air speed in a vertical dive. Most modern combat aircraft are equipped with air brakes, which perform the same function as dive brakes.  
A brake is a mechanical device that inhibits motion by absorbing energy from a moving system. It is used for slowing or stopping a moving vehicle, wheel, axle, or to prevent its motion, most often accomplished by means of friction.
A dive bomber is a bomber aircraft that dives directly at its targets in order to provide greater accuracy for the bomb it drops. Diving towards the target simplifies the bomb's trajectory and allows the pilot to keep visual contact throughout the bomb run. This allows attacks on point targets and ships, which were difficult to attack with conventional level bombers, even en masse.
The Arado Ar 240 was a German twin-engine, multi-role heavy fighter aircraft, developed for the Luftwaffe during World War II by Arado Flugzeugwerke. Its first flight was in 1940, but problems with the design hampered development, and it remained only marginally stable throughout the prototype phase. The project was eventually cancelled, with the existing airframes used for a variety of test purposes.
The Northrop X-4 Bantam was a prototype small twinjet aircraft manufactured by Northrop Corporation in 1948. It had no horizontal tail surfaces, depending instead on combined elevator and aileron control surfaces for control in pitch and roll attitudes, almost exactly in the manner of the similar-format, rocket-powered Messerschmitt Me 163 of Nazi Germany's Luftwaffe. Some aerodynamicists had proposed that eliminating the horizontal tail would also do away with stability problems at fast speeds resulting from the interaction of supersonic shock waves from the wings and the horizontal stabilizers. The idea had merit, but the flight control systems of that time prevented the X-4 from achieving any success.
A flap is a high-lift device used to reduce the stalling speed of an aircraft wing at a given weight. Flaps are usually mounted on the wing trailing edges of a fixed-wing aircraft. Flaps are used to reduce the take-off distance and the landing distance. Flaps also cause an increase in drag so they are retracted when not needed.
In aeronautics, air brakes or speed brakes are a type of flight control surface used on an aircraft to increase the drag on the aircraft. Air brakes differ from spoilers in that air brakes are designed to increase drag while making little change to lift, whereas spoilers reduce the lift-to-drag ratio and require a higher angle of attack to maintain lift, resulting in a higher stall speed.
The Schempp-Hirth Mini Nimbus is a 15 Metre-class glider designed and built by Schempp-Hirth GmbH in the late 1970s.
The Northrop BT was an American two-seat, single-engine monoplane dive bomber built by the Northrop Corporation for the United States Navy. At the time, Northrop was a subsidiary of the Douglas Aircraft Company. While unsuccessful in its own right, the BT was subsequently redesigned into the Douglas SBD Dauntless, which would form the backbone of the Navy's dive bomber force.
The Curtiss XBTC was a prototype single-seat, single-engined torpedo/dive bomber developed during World War II for the United States Navy. Four aircraft were ordered, powered by two different engines, but the two aircraft to be fitted with the Wright R-3350 radial engine were cancelled in late 1942, leaving only the pair using the Pratt & Whitney R-4360 radial. By this time, Curtiss Aircraft was overwhelmed with work and the Navy gave the XBTC-2 prototypes a low priority which delayed progress so the first flight did not take place until the beginning of 1945. One aircraft crashed in early 1947 and the other was disposed of later that year.
The Schweizer SGS 1-23 is a United States Open and Standard Class, single-seat, mid-wing glider built by Schweizer Aircraft of Elmira, New York.
The PIK-3 was a sailplane produced in Finland in the 1950s and 60s. It was designed to be a cheap and easy-to-build aircraft to equip the country's gliding clubs as their standard single-seat machine. It was a conventional design for its day, with a high wing and conventional empennage. Construction was of wood throughout, skinned in plywood.
The SZD-19 Zefir is a single-seat glider aircraft that was designed and built in Poland from 1957.
The IS-4 Jastrząb was a single-seat aerobatic glider designed and built in Poland from 1949.
The Slingsby Type 34 Sky is a high performance single seat competition sailplane built in the United Kingdom. It was successful in major events, particularly in the World Gliding Championships of 1952.
A glider or sailplane is a type of glider aircraft used in the leisure activity and sport of gliding. This unpowered aircraft can use naturally occurring currents of rising air in the atmosphere to gain altitude. Sailplanes are aerodynamically streamlined and so can fly a significant distance forward for a small decrease in altitude.
The Slingsby Type 45 Swallow was designed as a club sailplane of reasonable performance and price. One of the most successful of Slingsby's gliders in sales terms, over 100 had been built when production was ended by a 1968 factory fire.
The Ikarus Košava is a two-seat sailplane designed and built in Yugoslavia in the early 1950s. It won the 1954 World Gliding Championships in the two seat category and came second in the same event two years later.
The Ikarus Meteor is a long-span, all-metal sailplane designed and built in Yugoslavia in the 1950s. It competed in World Gliding Championships (WGC) between 1956 and 1968 and was placed fourth in 1956; it also set new triangular-course world speed records.
The Beatty-Johl BJ-2 Assegai was a single seat, high performance competition glider built in South Africa in the early 1960s. Only one was built; it was optimised for South African conditions and performed well there, winning two nationals and setting several records, but was less successful under European conditions at the 1965 World Gliding Championships.
The Civil Aviation Department Ashvini was the first two-seat glider designed and built in India. It was produced in small numbers in the early 1960s.