Dome Calculators
October 24, 2006
by David South, Jr.
Dome calculations are painful to do by hand. It's not impossible, just time consuming. So I have written this simple calculation worksheet to help. It will calculate the most commonly needed measurements for a dome -- both spherical or oblate.
For either calculation you enter the diameter, height, stemwall, and level information then click 'Calculate.' to get the results. Remember, if you change any one of these values, you must hit 'Calculate' again.
We also have the advanced calculator including the prolate calculations.
Spherical Dome Calcs Reference
- Diameter
- Diameter of the base of the dome. (see diagram above)
- Height
- Height of dome from base to apex. (see diagram above)
- Stemwall
- Vertical wall equal in diameter to the base of the dome extending from the base down to the ground. For hemispheres -- where the height is equal to half the diameter -- the stemwall can usually be inflated as part of the Airform. For low-profile spheres, the stemwall will have to be built before inflating the Airform -- this is the Orion style dome (see Italy High School). For Orion style Monolithic Domes, you must make the Stemwall tall enough to accomodate a doorway -- usually 8 feet minimum. For Airform style Stemwalls, it can be any height. (see diagram above)
- Radius of Curvature
- The distance to the center of the sphere described by the dome. Spherical domes are part of a larger sphere. For a hemisphere, the radius of curvature is equal to the height and equal to the radius of the base. (see diagram above)
- Circumference
- Distance around the perimeter of the dome.
- Floor Area
- Area of the floor. The floor is defined as a circle equal to the diameter of the base of the dome.
- Surface Area
- Dome, Stemwall, and Total Surface Area describe the surface area of the dome and stemwall separately and then totals the two together.
- Volume
- Dome, Stemwall, and Total Volume describe the cubic volume contained by the dome and stemwall separately and then totals the two together.
- Level
- The level above the base of the dome to calculate radius and area. (see diagram above)
- Radius @ Level
- The horizontal radius at the 'Level' specified. (see diagram above)
- Area @ Level
- Area of the circle described by the Radius @ Level. (see diagram above)
Oblate Ellipsoid Dome Calcs Reference
- Diameter
- Diameter of the base of the dome. The semi-major axis (a) of the ellipsoid will be defined as half of the diameter. (see diagram above)
- Height
- Height of dome from base to apex. The semi-minor axis (b) of the ellipsoid will be defined as equal to the height. (see diagram above)
- Stemwall
- Vertical wall equal in diameter to the base of the dome extending from the base down to the ground. For half-ellipsoids -- where the height is equal to half the diameter -- the stemwall can usually be inflated as part of the Airform. These formulas are setup to only calculate half-ellipsoids. Orion style walls may be built if you choose, however, low profile spherical domes may be more appropriate. (see diagram above)
- Ellipticity
- The ratio between the a and b of the ellisoid shape where 1.0 is a sphere, 1.35 is a moderately elliptical dome, and 1.45 is a highly elliptical dome.
- Circumference
- Distance around the perimeter of the dome.
- Floor Area
- Area of the floor. The floor is defined as a circle equal to the diameter of the base of the dome.
- Surface Area
- Dome, Stemwall, and Total Surface Area describe the surface area of the dome and stemwall separately and then totals the two together.
- Volume
- Dome, Stemwall, and Total Volume describe the cubic volume contained by the dome and stemwall separately and then totals the two together.
- Level
- The level above the base of the dome to calculate radius and area. (see diagram above)
- Radius @ Level
- The horizontal radius at the 'Level' specified. (see diagram above)
- Area @ Level
- Area of the circle described by the Radius @ Level.
177
Dome Park Place - Italy, TX 76651
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