def mass_surface_solid(
        chord,
        span,
        density=2700,  # kg/m^3, defaults to that of aluminum
        mean_t_over_c=0.08
):
    """
    Estimates the mass of a lifting surface constructed out of a solid piece of material.
    Warning: Not well validated; spar sizing is a guessed scaling and not based on structural analysis.
    :param chord: wing mean chord [m]
    :param span: wing span [m]
    :param mean_t_over_c: wing thickness-to-chord ratio [unitless]
    :return: estimated surface mass [kg]
    """
    mean_t = chord * mean_t_over_c
    volume = chord * span * mean_t
    return density * volume