German plane shows off its new design of retractable undercarriage.
Full title reads: "Berlin. Aviation's latest wonder. Whole under-carriage folds up during flight into wings of Germany's latest postal plane."
SV of Heinkel monoplane with engine running. The aeroplane takes off. Plane flies overhead showing that the landing gear / undercarriage have retracted and folded under the wings. Plane lands again.
Shots of plane in hanger demonstrating how the system for folding the landing gear works.