Coil geometry
Diameter, length, turns and inductance are four figures and only three are free. This gives the fourth, and says by how much a published set fails to close when it does.
solenoid L(µH) = r²N² / (9r + 10l) r, l in inches flat spiral L(µH) = r²N² / (8r + 11w) r mean radius, w radial width
Wheeler 1928, and nothing else. These are the forms the hobby quotes and they are within about one per cent over the shapes a Tesla coil uses. The solenoid form is stated for a coil at least 0.4 diameters long, and this page refuses to answer below that rather than quietly being wrong.
A tapped primary: enter the tap, not the winding. The turns in circuit and the diameter those turns reach are what decide the inductance. Checked against three published machines, entering the whole spiral instead puts the smallest of them twenty per cent out on its own. Their turn spacing is a gap, so the pitch is conductor plus spacing, which their stated outside diameters confirm to under half a millimetre.
Close wound, single layer, air cored. A space wound secondary reads a little low here, and a coil on a ferrite floor is a different problem entirely.
No self capacitance and therefore no frequency. That is the other half of a resonator and it is not Wheeler's. Take it from a measurement or from a modeller, and put both into primary tank or coupled poles.