Rodney Gibbes joined the Air Force in July 1936 .
Two of Gibbes ' cousins -- both born in 1915 and , like Bobby , only sons -- were also pilots in the RAAF .
Rodney Gibbes joined the RAAF   in July 1936 .
Two of Gibbes ' cousins -- both born in 1915 and , like Bobby , only sons -- were also pilots in the RAAF .