Propeller (Propulsive) Efficiency
Compute a propeller's propulsive efficiency, η = (T·V/P)·100%, the ratio of useful propulsion power (thrust × speed) to the power delivered to the shaft. It measures how much of the engine power the propeller converts into forward thrust — well-designed propellers reach 80–88% in cruise. It drops sharply at low speed (takeoff) and near the speed of sound at the blade tips. Enter the thrust, the speed and the shaft power.
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Propeller (propulsive) efficiency
A propeller is a wing that spins: it converts the shaft power delivered by the engine into thrust. The propulsive efficiency η = (T·V/P)·100% measures what fraction of that shaft power becomes useful propulsion (thrust × forward speed). Well-designed propellers reach 80–88% in cruise — better than many jet engines at low speed. But the efficiency collapses in two situations: standing still on the ground (zero forward speed → thrust with no advance, η→0) and when the blade tips approach the speed of sound, where shock waves and noise take over. That is exactly why propellers use variable pitch and have a practical speed ceiling. Enter the thrust, the forward speed and the shaft power.
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Breguet Range (Jet Aircraft)
Calculates a jet aircraft's cruise range with the Breguet equation: speed divided by thrust specific fuel consumption, times the aerodynamic efficiency, times the natural logarithm of the ratio between weight at the start and at the end of cruise. Valid for cruise with V, specific fuel consumption and L/D held constant — in practice the cruise-climb, at fixed Mach and lift coefficient, or step-climb flight. Enter the speed, TSFC, L/D and both weights.
Bearing Power Loss
Calculate the power dissipated by friction in a bearing, P = T × ω, multiplying the friction torque T by the angular velocity ω (rad/s). The result, in watts, is the mechanical energy converted to heat per unit time by friction — a loss that reduces efficiency and heats the lubricant and components. This heat must be dissipated (by convection or oil circulation) to keep a safe operating temperature, since overheating degrades the lubricant and can cause seizure. Estimating the dissipated power is essential to size the cooling and the oil flow. Enter the friction torque and the angular velocity.
Power by Admiralty Coefficient
Estimate a ship's propulsive power by the Admiralty formula, P = (∆^(2/3)·V³)/C, from the displacement (∆, t), the speed (V, knots) and the Admiralty coefficient (C), characteristic of similar hulls. It is a classic, fast method to predict the required power in the preliminary design stage, based on similarity with existing ships. The V³ dependence shows the high cost of speed. Enter the displacement, the speed and the coefficient C.
Aircraft Fuel Efficiency
Compute aircraft fuel efficiency = distance / fuel.
Brake Power Dissipated
Calculate the power dissipated by a brake under torque, P = T·(2π·n/60), from the braking torque T (N·m) and the rotation n (rpm). Dissipated power is the rate at which the brake converts mechanical energy to heat — the product of braking torque and angular velocity. It differs from total braking ENERGY: energy is the total heat generated (joules), while power is the INTENSITY of that heat generation (watts), and it determines the brake's steady-state temperature. A brake dissipating much energy but slowly (low power) heats little; one dissipating the same energy fast (high power) heats much more. Dissipated power is critical in brakes working CONTINUOUSLY or repetitively: retention brakes on long descents, industrial equipment brakes (hoists, cranes, conveyors holding load), and dynamometers (which measure engine power precisely by dissipating it in a brake). There, the steady-state dissipated power sets the COOLING capacity needed (ventilation, water cooling) to keep temperature stable. Equating dissipated power to cooling capacity gives the equilibrium temperature. Enter the braking torque and the rotation.
Axle Load Equivalency Factor
Computes how many passes of the standard axle are equivalent to one pass of the real axle, using the power law of pavement design: factor = (axle load ÷ standard axle load) raised to the damage exponent. This factor is what converts a traffic count into the number N of standard axle repetitions, which in Brazil is the 8.2 tf, or 80 kN, single axle with dual wheels. The exponent amplifies overload brutally: an axle 20% heavier than the standard does not consume 20% more pavement but 2.07 times as much, which is why a single overloaded truck weighs more on the life of the road than thousands of cars, whose factor is practically zero. The exponent is an input rather than fixed at 4, the AASHTO value known as the fourth power law, because rigid pavement and fatigue cracking models work with exponents between 3 and 5 and the result shifts by a whole level depending on the choice. Enter the axle load, the standard axle load and the damage exponent.
The results provided by this tool are for general informational and educational purposes only and do not constitute professional, financial, medical, legal, tax or accounting advice. Always confirm important decisions with a qualified professional and official sources.