Model Engineering Glossary

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Radial Engine

Cylinders arranged radially around the crankshaft. In this case a 1850hp Wright R-2600-29 Cyclone 14-cylinder radial. Note that this is effectively two 7 cylinder radials back to back with the rear bank of cylinders being rotated half the cylinder to cylinder spacing.

See also:Engine Configurations.

Radiation

This is the electromagnetic radiation emitted by a body as a function of its temperature. The idealised body is a black body, this being one which absorbs all radiation that impinges on it. Stefan's law states that the total energy radiated per unit time per unit surface area of a black body is proportional to the fourth power of the temperature (kelvins) of the body.

E=sT⁴

where s = Stefan's constant = 5.67x10^-8Wm^-2K^-4

See also: Heat, Physical Constants.

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Red Gold

25 % Copper 75 % Gold

Red Lead

Chemical name: Plumbate

Chemical formula: 2PbO PbO₂

See also: Chemical Table.

Reith's Alloy

74.5 % Copper 9 % Lead 11.6 % Tin 4.9 % Antimony

Resistors

The basic laws relating to resistors.

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Rheostan

84 % Copper 4 % Zinc 12 % Manganese

Rivet

Used to permanently fix two or more sheets of metal together.

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Rotary Engine

Rotary engines were used extensively in early aircraft. Note that with a rotary engine the crankshaft is fixed and does not rotate, the propeller is fixed to the crankcase and the whole crankcase rotates with the propeller.

See also:Engine Configurations.

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