Nice one Adrian I particularly like the sketches and your method for changing units between SI and US (maybe this is an approach I could introduce in my own work). I see what you mean about the calculations on worksheets 'Calc1' and 'Calc2' being short but they are useful. worksheets 'Calc3' is difficult to encode because the acceleration curve is discontinuous. Its a bit like a shear force diagram with points loads on a beam may be you could take inspiration from calculations like
Alex Tomanovich's BEANANAL.xls. Alternatively you could encode a problem with a
continuous acceleration curve.
Remember to raise the issue number of the repository upload when you update your calculation. Well done so far.