Complex sentence: The airplane stands on a sprung and retractable main undercarriage with a six-inch hub diameter, placed at the center of gravity and a nose wheel, which is likewise sprung and retractable via the same lever in the cockpit.
Split into simpler sentences: The airplane stands on a sprung and retractable main undercarriage with a large six-inch diameter wheel hub placed at the center of gravity. This location requires a nose wheel, which is likewise sprung and retractable via the same undercarriage lever in the cockpit.