BEML Junior Executive flashcards

33 cards. Read the term and the definition here. The deck at the top of this page is optional.

Induced drag formula

Induced drag equals lift squared divided by the product of dynamic pressure, pi, Oswald efficiency, and span squared. It decreases with larger wingspan and higher speed at fixed lift.

Stall speed relation

Stall speed equals the square root of twice the wing loading divided by air density times maximum lift coefficient. Higher wing loading or lower C_Lmax raises stall speed.

Bypass ratio

The ratio of mass airflow through the fan bypass duct to that through the engine core. High bypass ratios improve propulsive efficiency and reduce fuel burn at subsonic cruise.

Breguet range equation

Range equals velocity divided by specific fuel consumption, multiplied by lift-to-drag ratio and the natural log of initial over final weight. It quantifies payload-range trade-offs.

Radar range equation

Maximum detection range scales with the fourth root of transmitted power, antenna gain squared, wavelength squared, and target radar cross-section, divided by receiver noise.

ISA sea-level values

International Standard Atmosphere at sea level specifies 101.325 kPa pressure, 15 degrees Celsius temperature, and 1.225 kilograms per cubic metre density, with a 6.5 degree per kilometre lapse rate.

Drag divergence Mach number

The Mach number at which drag begins rising sharply as shock waves form on the wing. Thin airfoils and sweepback raise this number, enabling higher cruise speeds.

Specific fuel consumption

Fuel flow required per unit of thrust or power produced. Lower values indicate greater efficiency and directly improve range and endurance in aircraft performance calculations.

Thrust-to-weight ratio

Engine thrust divided by aircraft weight. It determines climb gradient, acceleration, and takeoff distance; values above one permit vertical climb in some fighters.

Angle of attack and lift

Lift coefficient rises nearly linearly with angle of attack until the critical angle, beyond which the wing stalls and lift drops sharply while drag increases.

Excavator cycle time

The time for digging, swinging loaded, dumping, and returning empty. Productivity falls as swing angle increases beyond ninety degrees because swing time grows.

Bucket fill factor

A multiplier applied to struck bucket capacity to estimate heaped capacity. Values range from about 0.8 for rocky material to over 1.0 for loose, free-flowing soil.

Swell factor

The percentage increase in volume when bank material is excavated and loosened. Loose volume equals bank volume multiplied by one plus the swell fraction.

Shrinkage factor

The reduction in volume when excavated material is compacted in a fill. Compacted volume equals bank volume divided by one minus the shrinkage fraction.

Match factor

Trucks multiplied by truck cycle time, divided by loaders multiplied by loader cycle time. A value near one indicates a balanced fleet with minimal waiting.

Grade resistance

The force opposing motion on a slope, approximately ten kilograms per tonne per percent grade. It adds to rolling resistance when hauling uphill and subtracts downhill.

Rolling resistance

Resistance from tire or track deformation and surface condition, expressed as a percentage of gross vehicle weight. It is typically higher on soft or loose haul roads.

Slot dozing

A dozing technique where a narrow trench is cut and material is pushed along it. Material between the tracks reduces spillage and increases blade load.

Track tension setting

Crawler track sag measured at mid-span between sprocket and idler, checked against the manufacturer specification. Incorrect tension accelerates pin, bushing, and sprocket wear.

Specific energy in drilling

Energy required to remove a unit volume of rock. It decreases as thrust, rotation speed, and flushing are optimized for the rock type being drilled.

Ripper production estimate

Production equals material volume per pass multiplied by passes per hour and job efficiency. Pass spacing and rippability of the rock govern the volume per pass.

Equilibrium cant formula

Equilibrium superelevation in millimetres equals gauge in millimetres times speed in kilometres per hour squared, divided by 127 times curve radius in metres.

Cant deficiency

The difference between equilibrium cant and actual applied cant. It represents unbalanced lateral acceleration and is limited to protect passenger comfort and track stability.

Maximum curve speed

Permissible speed squared equals the sum of actual cant and permitted cant deficiency, multiplied by radius, divided by a constant near 11.8 for broad gauge.

Transition curve length

Length equals cant multiplied by speed, divided by the permitted rate of change of cant. It ensures gradual introduction of curvature and superelevation.

Thermal rail expansion

Change in rail length equals the coefficient of thermal expansion for steel, about 1.15 times ten to the minus five per degree, times original length times temperature change.

Stress-free temperature

The rail temperature at which continuous welded rail carries no longitudinal thermal stress. It is set during installation and determines the safe temperature range.

Adhesion limit

Maximum tractive force equals the adhesion coefficient multiplied by adhesive weight. Wheel-rail contamination from leaves, oil, or water can reduce the coefficient sharply.

Signalling headway

Minimum time between successive trains, comprising braking distance, overlap, sighting distance, train length, and station dwell, divided by operating speed.

Traction power equation

Mechanical power equals tractive force multiplied by velocity. It is used to size traction motors and substations for a given train mass and schedule speed.

Third-rail versus overhead

Third-rail DC systems, commonly 750 volts, suit metros with tight tunnels. Twenty-five kilovolt AC overhead suits mainline routes with higher power demand.

Metro tunnel ventilation

Longitudinal or transverse ventilation systems remove heat and smoke. Cross-passages and walkways provide emergency egress at intervals set by fire-life-safety standards.

Track modulus

Vertical stiffness of the track structure per unit rail deflection. Rail section, sleeper spacing, and ballast depth determine it and influence dynamic wheel loads.