OXYL8 have developed a free LEV App for Android and iPhones which will (using Fletcher’s Equations) calculate the Hood Entry Velocity required for any shape of Captor Hood.
The equations cannot be run backwards eg to determine Captor Distance (trust me several uni maths people have tried! :-)) but by typing in different distances into the App until you get the actual Hood Entry Velocity you have just measured – then by simple trial and error – you can arrive at the Captor Distance.
Give it a ‘go’ and you will see how intuitive it is.
The links to the App download pages on Apple and Google App Stores can be found here: