11/10/06

How we design our vehicles

•         In 1999 we designed our own two seat hybrid vehicle completely from scratch. It required lots of home made parts, had reasonable performance but was limited by poor reliability.

•         In 2000 we purchased a set of drawings for a Greenspeed GR 16/19 recumbent trike, which has been the starting point of all our vehicle chasses up to Fill. However, our vehicles have evolved considerably from the original Greenspeed design to be quite unique. Crossover steering rods and centre spine layout are about all that remain of original Greenspeed design.

•         Modifications to Greenspeed design now  include:-

            - lowered centre of gravity.

            - steering altered to fit in Weeroona canopy, under-seat handlebars.

            - adjustable headrest to suit range of rider sizes. No need for cushions.

            - less expensive construction of king pins and rear axle dropouts.

            - easier to remove Aramid composite seat.

            - offset rear axle mounting to suit asymmetrical rear wheel.

            - steering Ackermann altered to better suit racing conditions.

            - steering arms repositioned to allow for easy canopy removal.

•         Canopy design was conceived in 2000 using ‘clam shell’ concept from Bendigo Senior SC but with our own shape and features. Canopy shape has been modified a few times and a separate ‘junior’ canopy mould for primary HPV’s has been adapted from the ‘senior’ one.

•         Technology teacher and program coordinator, John Taylor, is the chief ‘design engineer’.

•         Students perform some specific design tasks depending on skills and ability of students.

•         A range of information sources have been researched for the development of our vehicles; Greenspeed, USA patents office, IHPVA, observation of competitors, aerodynamic engineers, trades-people, etc.

•         Our major design constraints and  considerations in descending order are:

          1       Rule compliance: must meet all event rules, ie. vehicle dimensions

          2       Ergonomics; must accommodate riders satisfactorily. However, it is a racing vehicle, not a limousine.

          3       Physical environment; specifically air and gravity. To move freely through air requires good aerodynamics. Gravity acts on a vehicle's total mass to create issues when accelerating, hill climbing, cornering and in the rolling of tyres.

4       Systems: drive-train, steering etc.

5      Structure: chassis and canopy.

6       Aesthetics. This tends to go with good aerodynamics as a good streamlined shape will usually look good. Attractive vehicles attract students and promote positive attitudes to the activity.

7      Durability and ease of construction and maintenance; We want the vehicles to last a few years and be easy for students and newcomers to work on. This enables us to build up a fleet so more students can be involved at different levels. This tends to increase mass, a compromise is required.