For an independently established mean effective pressure pme, swept volume per revolution Vrev and shaft speed N, indicated work per revolution is Wrev = pmeVrev and indicated power is Pi = pmeVrevN/60. These are internal cycle values, not measured brake output or a rating for an unspecified historical engine.
Selected Indicated Work and Power
Calculate indicated work, mean indicated torque and indicated power from independently established mean effective pressure, swept volume per revolution and speed.
Equation Used
- Mean effective pressure is a valid net cycle-average value, not supply pressure.
- Swept volume is total active volume displaced per shaft revolution.
- Selected speed is steady and nonnegative.
- Leakage, friction, auxiliaries, transmission losses, transients and ratings are excluded.
The animation is illustrative topology only and does not define the selected swept volume or pressure cycle.
Historical topology and calculation boundary
The catalogued form is interpreted as a circular casing, rotating member with a radial working element and a retracting abutment. The visual shows that relationship schematically without assigning ports, seals or timing.
The calculator does not derive mean effective pressure or swept volume from the drawing. Enter only values obtained from a defined design, measurement or separately justified cycle model.
What the calculator determines
From selected pme, Vrev and N, the calculator returns indicated work per revolution, mean indicated torque, indicated power in kilowatts and indicated horsepower.
It does not determine brake power, efficiency, steam consumption, port capacity, safe speed, pressure rating, sealing, losses, durability or suitability for a particular load.
Selected indicated-work model
Wrev = pmeVrev. Mean indicated torque is Ti = Wrev/(2π). With N in rpm, Pi = WrevN/60 watts. The calculator converts bar to pascals and litres to cubic metres before applying these identities.
Mean effective pressure is cycle work divided by swept volume; it is not supply or boiler pressure. Establishing it requires an indicator diagram or a defined pressure-volume path.
Selected-input example
For pme = 5.0 bar, Vrev = 4.0 L/rev and N = 300 rpm, indicated work is 2,000 J/rev, mean indicated torque is 318.31 N·m and indicated power is 10.000 kW or about 13.41 hp.
Those values follow exactly from the selected inputs. They do not establish brake output because mechanical, leakage, auxiliary and transmission losses are not included.
Correction and safety boundary
The former calculator's core indicated-work equation was retained, while the arbitrary speed index was removed. The former article also supplied unsupported histories, pressure and speed bands, clearances, tolerances, materials, efficiencies, maintenance rules, failure diagnoses and a fabricated museum example.
Those unsupported claims and the unrelated video are removed. This page is a bounded calculation aid, not a construction, restoration, operating or steaming guide.
Questions
Can boiler pressure be entered as mean effective pressure?
Not generally. Mean effective pressure represents net cycle work divided by swept volume and must come from a defined pressure-volume cycle or measurement.
Is the result shaft power?
It is indicated internal power. Brake or delivered power is lower by the actual mechanical, leakage, auxiliary and transmission losses.
Does the calculator predict a high-speed power drop?
No. Speed is multiplied by a user-supplied constant mean effective pressure. Any change of filling, pressure, leakage or loss with speed must be modeled separately.
Does the animation define displacement?
No. It is illustrative topology and is not dimensioned.
Historical and technical references
- G. D. Hiscox, Mechanical Movements, Powers, Devices and Appliances — historical rotary-engine arrangements for topology context.
- T. W. Barber, The Engineer's Sketch-Book — period collection showing varied rotary-engine layouts behind broad form labels.
- OpenStax University Physics, Work, Heat, and Internal Energy — pressure-volume work requires integration along a defined path.
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