The inspiration for the design of the Vespa dates back to Pre-WWII Cushman scooters made in Nebraska, USA. These olive green scooters were in Italy in large numbers, ordered originally by Washington as field transport for the Paratroops and Marines. The US military had used them to get around Nazi defense tactics of destroying roads and bridges in the Dolomites (a section of the Alps) and the Austrian border areas.
Pre-war Piaggio employee Aeronautical engineer General Corradino D'Ascanio, responsible for the design and construction of the first modern helicopter by Agusta, was given the job of designing a simple, robust and affordable vehicle for Ferdinando Innocenti, whose pre-war metal tubing business Innocenti had suffered the same fate as Piaggio post-war. Innocenti defined a post-war vehicle to D'Ascanio that had to be easy to drive for both men and women, be able to carry a passenger, and not get its driver's clothes dirty.
D'Ascanio, who hated motorbikes, designed a revolutionary vehicle. It was built on a spar-frame with a handlebar gear change, and the engine mounted directly on to the rear wheel. The front protection "shield" kept the rider dry and clean in comparison to the open front end on motorcycles. The pass-through leg area design was geared towards all user groups, including women, as wearing dresses or skirts made riding a motorcycle a challenge. The front fork, like an aircraft's landing gear, allowed for easy wheel changing. The internal mesh transmission eliminated the standard motorcycle chain, a source of oil, dirt, and aesthetic misery. This basic design allowed a series of features to be deployed on the frame, which would later allow quick development of new models.
However, D'Ascanio had a falling-out with Innocenti, who rather than a molded and beaten spar-frame wanted to produce his Innocenti frame from rolled tubing, thereby allowing him to revive both parts of his pre-War company. D'Ascanio disassociated himself with Innocenti, and took his design to Enrico Piaggio to produce the spar-framed Vespa from 1946. Innocenti, after overcoming design difficulties and later production difficulties through his choice of a tubular frame, went on to produce the more costly Lambretta line of motorscooters.
On 23 April 1946, at 12 o'clock in the central office for inventions, models and makes of the Ministry of Industry and Commerce in Florence, Piaggio e C. S.p.A. took out a patent for a "motorcycle of a rational complexity of organs and elements combined with a frame with mudguards and a casing covering the whole mechanical part".
The basic patented design allowed a series of features to be deployed on the spar-frame which would later allow quick development of new models. The original Vespa featured a rear pillion seat for a passenger, or optionally a storage compartment. The original front protection "shield" was a flat piece of aero metal; later this developed in to a twin skin to allow additional storage behind the front shield, similar to the glove compartment in a car. The fuel cap was located underneath the (hinged) seat, which saved the cost of an additional lock on the fuel cap or need for additional metal work on the smooth skin.
The scooter had rigid rear suspension and small 8-inch (200 mm) wheels that allowed a compact design and plenty of room for the rider's legs. The Vespa's enclosed, horizontally-mounted two-stroke 98 cc engine acted directly on the rear drive wheel through a three-speed transmission. The twistgrip - controlled gear change involved a system of rods. The early engine had no cooling, but fan blades were soon attached to the flywheel (otherwise known as the magneto, which houses the points and generates electricity for the bike and for the engine's spark) to push air over the cylinder's cooling fins. The modern Vespa engine is still cooled this way. The mixture of two-stroke oil in the fuel produced high amounts of smoke, and the engine made a high buzzing sound like a wasp.
The first prototype was given the initials MP5 and baptized "Paperino," the Italian name for Donald Duck, a nick-name given to it by the workers because of the strange shape it had. Enrico Piaggio did not like the design and asked D'Ascanio to redesign it which he did with a more aeronautical-derived aerodynamic look. When the second prototype called MP6, was shown to Enrico Piaggio and he heard the buzzing sound of the engine he exclaimed: "Sembra una vespa!" ("It resembles a wasp!") The name stuck. Vespa is both Latin and Italian for wasp derived from both the high-pitched noise of the two-stroke engine, and adopted as a name for the vehicle in reference to its body shape: the thicker rear part connected to the front part by a narrow waist, and the steering rod resembled antennae.
Ape (pronounced Ah-pay), is Italian for bee. This was the three-wheeled variant used for commercial purposes, including the popular auto rickshaw.
Source: Wikipedia Vespa Article