11. Faster aircraft usually have retractable undercarriages , which folds away during flight to reduce air resistance or drag. 12. Like most airliners it is a monoplane with fixed wings and has a retractable undercarriage in tricycle configuration. 13. This increases internal storage for fuel, retractable undercarriage , armaments and in some cases even passengers and crew. 14. The amphibious floatplane Otter features a unique four unit retractable undercarriage , with the wheels retracting into the floats. 15. More complex types, like those with retractable undercarriage or variable pitch props, require additional training and licensing. 16. It was a twin-engine, low-wing monoplane with a retractable undercarriage , and a tailwheel. 17. The resulting machine introduced several features not found on trainers : retractable undercarriage and trailing edge flaps amongst others. 18. As an amphibian the Kittiwake needed to have a retractable undercarriage , a most unusual feature at this time. 19. The F . K . 54 was most notable as Koolhoven's first aircraft with a retractable undercarriage . 20. Though the Discus and the Carat share wings, they position them differently : the Discus is a retractable undercarriage .
