Complex sentence: Lyle Shelton (1934-2010) was an American aviator who set a world speed record and won ten Unlimited air races, the most of all time, and six national championships, second only to Darryl Greenamyer.
Split into simpler sentences: Lyle Shelton (1934-2010) was an American aviator who set a world speed record. He won ten Unlimited air races, the most of any pilot, and six national championships, second only to Darryl Greenamyer.