Hovercraft Air Cushion Calculator

This hovercraft calculator will provide the general lift air requirements of your proposed hovercraft design. Use this information to assist in selecting the proper lift/pressure fan or air cushion size for the gross weight you intend to support. 

You should disregard the Estimated Fan Diameter and the Estimated Lift Engine Power outputs because they are not compatible with modern-day axial fan properties.

We use 4 inches of water gauge (in.wg.) static pressure (997 Pascal's) as our default pressure for the air cushion, which supports 20.8 pounds per square foot, or 101.6 kilograms per square meter of aircushion area. Generally, if your hovercraft weighs more than 15 pounds per square foot of aircushion area or 76 kilograms per square meter, it is TOO HEAVY for the air cushion area size you have provided which will require more engine power to generate more airflow and pressure to support the extra weight.

The shape of your hovercraft is assumed to be rectangular. A length to width ratio of 2 to 1 is the most stable shape for a hovercraft. If your hovercraft is of another shape (round, oval, etc.), then enter an estimated length and width dimensions that will approximate the air cushion area of your craft.  Tip:  Draw out air cushion shape to scale on graph paper, then count the whole and partial squares.

Always use the measurement from the ground contact point of the hovercraft skirt, not the outside, overall hovercraft hull dimensions.  The air gap you will specify is the distance between the ground and the "contact point" of the  hovercraft skirt, not the distance from the ground to the bottom of the hovercraft hull, and is typically 0.25 to 0.5 inch.  If you double the air gap, this will require double the air flow reqired from your fan.  If you reduce your desired air gap to 0.25", the air flow requirement will be cut in half, from from a 0.5" air gap. Using a 0.25" air gap is acceptable as well, and may generate a higher aircushion pressure--a good thing.

Hovercraft lift calculator

Enter the required data in the following fields, use the metric or imperial boxes, not both.  When done, press the "Calculate" button. The answers will appear below.  Press the "Clear Input" button before starting a new calculation.

Enter air cushion length in meters:  or feet: 
Enter air cushion width in meters:  or feet: 
Enter Amount of air gap required in mm (i.e. 6): or inches (i.e. 0.25): 
Enter max. gross weight of craft in kg:  pounds: 


Results below are computed from the Input Data above and
are to be considered approximate values only.


Approximate lift perimeter (m) (ft)
Total hover gap area (m^2) (sq. ft.)
Total cushion area (m^2) (sq. ft.)
Cushion pressure (N/m^2 = Pa) (lbs/sq. ft, PSF)
Cushion pressure (mm of water @ 4degC) (inches of water @ 60degF)
Expected actual air velocity (m/sec) (ft/sec)
Cushion air flow volume (m^3/sec) (CFS)
Estimated lift engine power (kW) (HP)
Estimated fan diameter (m) (inches)

Thanks are given to Alex Olshove for developing this calculator based on James Perozzo's book, Hovercrafting as a Hobby.
Additional credit is given to Juergen Schoepf for incorporating metric units of measure into this calculator. 


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