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Model Aircraft Glossary



In 1988, Daedelus, a human powered aircraft was flown 74 miles across the Aegaen Sea, piloted and propelled by Kanellos Kanellopoulos.

See also: Chronology of Flight.


A reference line or point from which measurements are taken.

Dead Man′s Curve

The combinations of altitude and airspeed from which structural damage to the helicopter will occur in case of a power failure. Also called the height velocity diagram.

Dead Stick

A term used to describe a power model making a glide approach after the engine has stopped.


Markings come in many different forms and are normally provided with the kit.

Decimal Prefixes

Decimal prefixes from tera to pico along with their multiplication factors. more......

de Havilland, Geoffrey

de HavillandGeoffrey de Havilland was one of the early ace pilots. He worked at the Royal Aircraft Factory and developed the BE 2 from the BE 1 in 1913. Perhaps he is best known for the DH60 Moth and the derivatives of this famous type.

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An aircraft with a wing of a triangular planform, the base of the triangle forms the trailing edge.


A device operated by a slow-burning fuse or by a mechanical or electronic timer that puts a free-flight aircraft into a super-stalled condition to bring it down after a pre-set flight time.

Diecast Models

Diecast models are produced by various manufacturers around the world. more...

See also: White Metal Modelling.

Diesel Engines

Diesel engines can offer a lot in terms of power to weight ratio and the ability to turn a large propeller. more...


When ailerons are set to give more up movement than down movement. This is to reduce the effect of adverse yaw.

Differential Control

Differential control is used in many areas of radio control. In modern digital radio systems it is a standard function. However, it may be generated to some extent by expediant use of the control arms on a servo. more......

See also: Servo.


A flight control system whereby instead of mechanical links (cables and pulleys) from the cockpit to the aircraft’s flight controls, wires carry electronic signals. These electric/electronic signals allow a pilot to "fly by wire". Digital refers to digital computer inputs in the system; some fly-by-wire systems use analog computers. Virtually all modern, fly-by-wire flight control systems are digital.


dihedralThe dihedral angle is the angle made between one wing and the horizontal, as viewed from the nose or tail of the aircraft. The uptilt of wing panels toward the tips. Dihedral is applied for purposes of stability and to provide a turning moment for rudder-only models.

See also: Anhedral, Polyhedral.

Disc Area

The area swept by the blades of the rotor. This is a circle with its center at the hub axis and a radius of longest blade length.

Disc Loading

The ratio of helicopter gross weight to rotor disc area.

Display Cases

Once complete it is a good idea to finish the model and keep it clean with a display case. There are a number of different ways in which a display case may be constructed. more......

Dissymmetry of Lift

The unequal lift across the rotor disc area resulting from the difference in the velocity of air over the advancing blade half and the retreating blade half of the rotor disc area.


A wheeled frame that a model sits on to effect a take-off. The dolly either remains on the ground or drops off almost immediately.


See: Cellulose Dope.

Doubled Butt Lap Joint

See also: Joints.


A second sheet of material fixed inside the main fuselage side sheets on each side. For added strength.

Double-Surface Wing

A wing which is covered on both top and bottom with paper, cloth or other material.


Douglas DC3One of the most famous aircraft of all time is the Douglas DC3. Renowned as an airliner, general transport and perhaps most significantly for the vital part it played in the Normandy landings and the Berlin airlift. Still in service as a passenger aircraft, general transport and in maritime pollution control.

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The slight tilting down of the engine or propeller thrust line to exert a slight downward pull under pressure. When mounting engines be it IC or electric always try and incorporate some down and right thrust. This will vary with prop size, power and model type.


In the circuit flying parallel with the runway in the opposite direction to take-off.


A force acting on an aeroplane resisting its acting on an aircraft in motion resisting the movement through the air.

Reference: Aerodynamics Glossary -

Dual Rates

A switch that can make controls more or less sensitive. Lower rates are better for beginners, who tend to overcontrol.

Ducted Fan

A small diameter multi-bladed fan, operated at high rpm inside a tube or duct. The ejected air provides thrust in the same way as a jet engine, which the ducted fan is often used to simulate.

Dummy Engine

Often with powered scale model aircraft the engine has a single cylinder or electric and so a dummy engine is required.

Dutch Roll

A side-to-side wallowing motion of a model, often caused by insufficient fin area.