Lonnie:

Radial firing order.

Looking at the engine from the front, pick any cylinder and name it #1. Usually this is the top cylinder, but not always. Makes no difference in the firing order though, you can start an any cylinder and it works.

Starting at your #1 cylinder, number them in order, in the same direction as propellor rotation.

The firing order is then first the odd numbered cylinders in order, followed by the even numbered cylinders in order. So a five would be 1-3-5-2-4- and repeat. The seven is 1-3-5-7-2-4-6- I'm sure you can take it from there.

Radials almost always have an odd number of cylinders per bank, there have been some few made with an even number. It is impossible to get even firing intervals with an even number of cylinders per bank with a four stroke engine, so the engineers just stayed with the odd numbers.

Bill.