def pad_position_l(self, i):
        """
        Determines the position of the ith pad in the length direction.
        Assumes equally spaced pads.

        :param i: ith number of pad in length direction (0-indexed)
        :return:
        """
        if i >= self.n_pads_l:
            raise ModelError("pad index out-of-bounds")
        return (self.length - self.pad_length) / (self.n_pads_l - 1) * i + self.pad_length / 2