SR-72 Darkbird Stealth and Speed:The SR-72 Darkbird Will Take Your Imagination On Super-Secret Missions To The Edge of Space Skill Level: 4 - Challenging Length: 35.6 cm (14.0''), Diameter: 18 mm (0.736'') Weight (no engine): 30.0 grams (1.05 oz) Recovery Type: Glider. Power pod (engine) comes down on via a streamer.