Ackermann’s Law of Steering Geometry Re-Visited

IMG_3083Today’s buyers of high-end sports cars such as Porsche and Ferrari are hardly aware that just below the refined gadgetry of their machines lies the bare skeleton of a 19th century wagon.

The configuration of movable stub axles at the front was a huge leap in technology at the time for maneuvering into narrow lanes and it also resolved the chronic problem of metallic outer rings flying off on a turn due to mis-positioned wheels.

Calculating the angle in the Ackermann manner to compensate for the inner wheel’s smaller circumference has remained the car standard but required tweaking for ultralight commuting. Spoke wheels, even the toughest ones made for bicycles have a low wobble tolerance when under the stress of being in the wrong position during a turn.

Rather than applying a swing action to a set of stub axles, we chose the ‘turn on a dime’ effect you get from a bike fork and re-jigged the equation to work in unison with or totally free of the tilt-control. Ackermann always applies since the full turn angle during slow maneuvers such as parking is 20 degrees on the outer wheel and 35 degrees at the inner measure.

Toucan’s floating capsule setup allows riders to sit side by side while retaining overall control of the dual rolling tilt frames. Experience has shown us that when the front wheels are pointing perfectly forward at speeds as low as 15mph, the slightest lean either left or right propels the vehicle in that direction, which ups the speed in the process to give a roller coaster effect with the added luxury of brakes.

Toucan’s exhaustively tested push-pull pitch control linkage ensures that when deliberately going into a leaning turn, hypersensitive left-right capability is always available to engage for minor corrections.

Returning to the upright position is even easier at high speeds but the process of shifting the vehicle weight and payload requires no more than 10lbs of application force in human push-pull power in all eventualities.

E-CAR-TALK

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