Digital-Fly-by-Wire

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.

Dihedral

The 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.

Dolly

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.

Dope

See: Cellulose Dope.

Doubled Butt Lap Joint

See also: Joints.

Doubler

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

One 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.

If you would like to see more pictures our photographic library is available on www.glue-it.co.uk.

Search for Douglas books on Amazon.co.uk

Downthrust

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.

Downwind

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

Drag

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

Search for aerodynamics books on Amazon.co.uk

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.