Complex sentence: The R38 made its first flight on 23 June 1921 and after some modifications to the rudder and elevators and a second test flight flew on the 17 July to Howden, East Riding of Yorkshire for airworthiness and acceptance trials.
Split into simpler sentences: The R38 made its first flight on 23 June 1921. After some modifications to the rudder and elevators, a second test flight flew on the 17 July to Howden, East Riding of Yorkshire for airworthiness and acceptance trials.