Case 15 / Rotorcraft aerodynamics
Rotorcraft power and climb analysis
Break helicopter power demand into induced, profile, parasite and tail-rotor contributions, then explore the ideal climb margin over airspeed.
Power breakdown · airspeed sweep · ideal climb analysisRotorcraft power modelling and performance analysis
How do airspeed and available power affect helicopter power demand and climb potential?
I modelled the main contributions to rotorcraft power demand and used the excess-power margin to estimate ideal climb performance. The interactive analysis varies airspeed and available power, showing how induced, profile, parasite and tail-rotor power combine across the operating range.
Method and workflow
- 01
Set the rotor
Specify the aircraft weight, rotor geometry, blade count, tip speed and air density.
- 02
Separate the terms
Calculate uniform-inflow induced power, a profile-power approximation and equivalent-flat-plate parasite power.
- 03
Account for the tail
Include a 6% tail-rotor power allowance and compare total demand with the selected power budget.
- 04
Read the margin
Convert excess power to ideal climb rate, while keeping advance ratio and model limits visible.
Four contributions. One power balance.
Air density 0.6531 kg/m³; weight 22,000 lbf; radius 28 ft; four blades; tip speed 650 ft/s. Tail allowance is 6% of main-rotor plus parasite power. Available power is the selected constant budget. A negative climb margin means the selected power budget is below the calculated level-flight requirement.
Model assumptions and scope
- The analysis uses a steady-flight, uniform-inflow approximation with simplified profile and parasite power terms.
- Air density is fixed at 0.6531 kg/m³. Available power is a selectable constant budget, with a default of 3,000 hp.
- The ideal climb estimate uses excess power divided by weight. Rotor flapping, compressibility and engine altitude lapse are outside this model.
Potential extensions
Compare the inflow approximation and power components with a documented rotorcraft reference case.
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