LIGHTWEIGHT, WRECK-RESISTANT CAR A vehicle, especially adapted for land travel, having strong, lightweight walls, comprising thin metal, cylindrical or corrugated cans, between skins, and surrounded by foamed plastic. These receptacles are sealed, thin-walled pipes or tubes; or rows of aligned short cans, end-to-end-glued together. The skins may be: metal sheets, epoxy glued or brazed to the cans; or metallic mesh attached to the cans by brazing or glue and/or bolts, coated with stucco. Optionally, each of the rows may comprise a plurality of aligned cans with adjoining end-caps that are strongly glued together, or a single, elongated, preferably corrugated tube. This invention pertains to lightweight and strong vehicles. Although its basic structure may be utilized in water-traversing vehicles, it is preferably incorporated in a wheeled vehicle, adapted for use on the land and also optionally in the air and in amphibious operation. One of its features comprises stabilization against roll of a two-wheeled or three-wheeled vehicle by providing balloon-lift approximately above its center of gravity. Light-weight, durable, land-traversing vehicle An automobile, wheeled aircraft or space craft, trailer, hovercraft, snowmobile, sled or other vehicle adapted for travel over land, having strong, light-weight frames that include elongated, vehicle-bracing beams (longitudinal stringers or optionally transverse ribs), having holes in their faces, and sealed bottles or the like, each having a pair of necks (or a neck and bottom) that are strongly glued in opposite holes of a pair of the vehicle-bracing pieces. The holes preferably are sockets, recesses, or depressions that do not extend thru the stringers or ribs. The beams may be of metal, but preferably are of waterproofed "Masonite" or other pressed wood, or of strong, molded or extruded plastic containing sufficient pores or reinforcing fibers for frictional holding of nails, or of cedar, cypress or other wood. Optionally and preferably, the beams are curved in the direction of their length. On their outer and inner edges metal or strong-plastic mesh (preferably expanded-metal lath, hardware cloth and/or poultry-type fencing) is nailed or screwed and/or glued. And on this mesh outer and inner layers of stucco (Portland cement, epoxy or other cement mixed with fine aggregate or fibers) are applied in pasty condition (by troweling or spraying) and allowed to set. Between these stuccoed skins, foamed plastic, from poured-in-situ liquids, imbeds the hollow elements. The vehicle is preferably curved in fore-and-aft direction; optionally it may also be curved vertically (i.e., barrel-curved), in which event, the bottle-holding holes preferably extend entirely thru the beams. The bottle-holding holes may be on each side of each beam and may be staggered, preventing interference of the holes and bottles on the opposite beam sides. Preferably, the vehicle includes: a pair of lateral wheel or runner supports, each having a flat, fore-and-aft inner surface and a curved outer surface; between these surfaces of each support a freely rotating, resiliently mounted wheel or runner; a narrow, streamlined, central, wheel support; and a front steering wheel and a rear driving wheel on the central support. The side wheels or runners ordinarily are clear of the ground, but contact it on sidewise tilting of the vehicle. Lateral and front buffers include foamed plastic and balloons imbedded in the plastic. These and optional other balloons inside the cabin, floating against the top, aid gyroscopic force in preventing tilting of the vehicle. Combination motorcycle and hang-glider A combination motorcycle and hang-glider comprising a triangular wing formed by a flexible sheet material affixed to a trifurcated frame structure which is pivotally attached to a vehicle, such as a motorcycle suspended below the wing by a plurality of truss members, whereby the wing and the vehicles are adjustably connected to each other. The frame structure includes pivotal means and means for changing the angle of attack of the wing to provide aerodynamic lift for the motorcycle.