Abstract: A variable-diameter blade suitable for a trans-media aircraft. The blade is divided into a blade root section, telescopic sections, and a blade tip section in a direction from the root to the tip. The blade further includes a telescopic rod, the blade root section and the blade tip section are fixed to the telescopic rod, respectively, and the telescopic rod is fixed to the trans-media aircraft; a spring arranged in the telescopic rod, the spring is used to drive the telescopic rod to extend; a pulley installed on the trans-media aircraft, the pulley is closer to the blade root section; a pull rope, an end of the pull rope passes through an inside of the blade and is fixed to the blade tip section, and the other end of the pull rope is wound on the pulley; and a driving device for driving the pulley to rotate.

Abstract: A polybenzoxazine aerogel film and a preparation method thereof are provided in the present disclosure, belonging to the field of preparation of aerogel film composite material. The preparation method of the polybenzoxazine aerogel film includes the following steps: dissolving benzoxazine monomer in a solvent and catalyzing to obtain a polybenzoxazine solution; coating the polybenzoxazine solution as a wet gel film; and aging and drying the wet gel film to obtain the polybenzoxazine aerogel film.