def func_rotor_weight_rotor_diameter(
    power: int, coeff_a: float, coeff_b: float
) -> float:
    """
    Returns rotor weight, in kg, based on rotor diameter.
    :param power: power output (kW)
    :param coeff_a: coefficient
    :param coeff_b: coefficient
    :return: nacelle weight (in kg)
    """
    rotor_mass = coeff_a * power ** 2 + coeff_b * power
    return 1e3 * rotor_mass