Does the length of your arms affect the power of an elbow strike? I was trying to work out if a longer arm would give more leverage to the blow.
There is a quote by John Von Neumann:
With four parameters I can fit an elephant, and with five I can make him wiggle his trunk.
Arm length is going to be just one of many variables (parameters) in the equation.
A longer, rigid arm moved through an arc is going to allow more speed, and given the same mass is going to hit with more energy.
Since most elbow strikes (that I can think of) are arcs, then yes a longer arm (more specifically the upper arm/humerus bone) will apply more force.
But really you're not talking about much of a difference. The average length of that bone (https://www.reference.com/science/average-length-humerus-bone-fb4ebf4c289dff34#) is 14.4 inches, and is (see link) alleged to be constant relative to height. So you're really not going to see a big difference in "normal" people. Whatever they are.
That said, technique (timing, hip rotation, angle) and raw strength will cause MUCH more variation and that's where you find your elephant (https://www.johndcook.com/blog/2011/06/21/how-to-fit-an-elephant/)