11/10/06

 The Weeroona Canopy Story

Weeroona has used distinctive canopies for its vehicles since 2000. Here is the inside story.

 History

The original idea of a front hinged composite canopy came from a Bendigo Senior Secondary College design of about 1996 which they used for only a few years. Their basic idea was refined from the outset in several areas:

·        The width was set flush with the front wheels for improved aerodynamics,

·        the frontal area was kept to a minimum with a narrow centre section and arches over the wheels,

·        the windscreen was placed well forward to minimize windscreen area and the consequent greenhouse effect, and

·        the height and length were reduced.

·        Internal wheel arches were added to enable effective support from the chassis.

·        The overall shape was designed to enable flat sheet windscreens to be used with good aerodynamic results.

·        The overall size and shape was designed to fit a Greenspeed GR 16/19 chassis.

Versions

The design has evolved over the years with several improvements and a junior version.

Version one

2000, Prius Junior. First design with inherent features of front hinged clam shell, ease of access and high aerodynamic performance. Whilst it was originally designed for HPV use, the first vehicle to use the canopy was a hybrid 2 vehicle (petrol engine and electric motor only, no pedals). The canopy used chopped strand fibre glass mat, polyester resin and was relatively heavy.

2001, Discovery, MAX (became eMAX in 2002). Lighter woven fibre glass cloth construction was used to achieve low mass. Rider ventilation was fitted but windscreen demisting was poor and canopies were a bit fragile and suffered in crashes. The two canopy halves were held together with ‘Velcro’ which proved to be insecure.

Junior version

2002, PJ2. The original Prius Junior canopy was used to make a plug for a smaller version of the canopy, suitable for hybrid 2 vehicles (no pedals) and primary HPV's. The length was reduced approx. 150 mm and the height was reduced approx. 100mm. The front windscreen opening was shaped to give a smoother airflow around the flat polycarbonate wind screen. St Therese’s were the first to use this canopy for a primary HPV on their eco racer vehicles. It has since been used to make our first primary vehicle, Bee Bee, in 2004. A positive action dual stage latch was made and fitted to all canopies.

Version two

2003, Rocky. Reduced frontal area was achieved with 65mm height reduction of lower canopy half. Alterations to chassis allowed roll-bar height clearance requirements to be still achieved. Improved flange system with use of Kevlar and rolled edges. Higher strength also achieved with the use of vinyl ester resin. Addition of forced air demisting to front screen proved effective.

Version three

2004, Reloaded. Lower half of mould altered at front wheels to improve airflow around wheels. A separate mould was made for the lower flange to make it stronger and easier to construct.  Lower wheel arch reshaped to allow chassis to be removed without any disassembly. The lower flange was further strengthened by the use of carbon fibre. Windscreen and side-screen demisting was further improved. Upper canopy was used as longitudinal brace for main roll bar. Side screens extended further back to meet new RACV field of vision rules. A new design canopy latch was made.

Version four

2005, Fill. A separate mould for the top flange was made to simplify construction and to allow a small height reduction of the canopy top. The rear-view mirror openings were deleted and smoothed over to improve laminar air flow. The canopy shell was made of one layer of Kevlar and one layer of fibre glass. The mould was modified so the screens could be fitted into a recess and finish flush to the exterior surface. The windscreen was blow formed to give a convex shape which should further improve aerodynamics. Previously the main rollbar was made of chrome molly but it is now made of carbon fibre and is integral with the canopy top.

Construction

The canopy as fitted to Reloaded is constructed mostly of fibre glass woven cloth using vinyl ester resin for low cost. It is considered that this gives adequate strength without excessive mass for most of the canopy. Kevlar panels are added for strength and abrasion resistance in the event of a roll over. Carbon fibre is used for the flanges where high strength and rigidity is required.

The latest canopy, Fill, uses Kevlar and woven glass for the main canopy skin instead of fibre glass. This gives greater crash resistance. Other parts of the canopy are constructed similar to Reloaded. Four main moulds are now used; two large moulds for the main top and bottom halves, and two perimeter moulds for the reinforcing flanges for each half. Small moulds are used for front support and light boxes. The two lower castings are assembled with Sikaflex 227 whilst all other parts are assembled with resin. The front and rear roll bars are integral with the canopy top and are made of carbon fibre over polyurethane foam. Special permission was granted from the chief scrutineer of the RACV Energy Breakthrough for this construction of the roll bars.

The two halves are quite strong and rigid on their own and when the lower half is attached to the chassis and the upper half is closed, a very high strength protective shell is achieved. The top is held in place by the hinge, latch and locating pegs. A foam sealing strip is fitted around the perimeter of the join.

Features

The evolution of the design has resulted in a canopy with many desirable features.

Aerodynamics. Smooth teardrop shape with minimal frontal area and high ground clearance. Small frontal area has been achieved by reducing canopy width above front wheels. Because the horizontal join line between the canopy halves is in the direction of airflow, any irregularities in the join do not effect the airflow. The natural high and low pressure areas of the aerodynamic shape have been utilized to create efficient ventilation for rider comfort and windscreen demisting. Air inlet and exhaust have been achieved without adding scoops which contribute drag. Circuit testing has shown a reduction of about 20% in lap time compared to a chassis with no canopy.

Low mass. The inherent strength of the shape of the two canopy halves has enabled the minimum use of materials.  The integral nature of side impact protection and roll bars with the canopy support flanges enables a high standard of safety to be met without the use of additional structures and mass.  High strength materials have been used in strategic high stress areas to give strength without mass.

Primary safety (accident prevention) is achieved in several ways.

1.      Good visibility. Clear polycarbonate windscreens cover a wide angle of vision.

2.      Good ventilation. Rider safety and performance is enhanced with an effective ventilation system which directs air to the riders head without compromising aerodynamics.

3.      Good windscreen demisting. The effectiveness of the ventilation and demisting system was proven in the 2003 RACV EB when light rain fell for many hours. We were able to continue racing with good visibility unlike many of our competitors who had great problems with windscreen fogging. The demisting of the 2004 model is further improved with wider outlets and side screen demisting.

4.      Minimal glass area to reduce greenhouse effect and heat build up in canopy.

5.      Width of front track gives stable vehicle.

Secondary safety (protection in an accident) is achieved in several ways.

1.   Fully enclosed front wheel arches prevent bodily contact with wheels at any time.

2.   Reinforcing to canopy in strategic areas provides protection against abrasion and impact. The required side impact protection and front roll bar is integral to the canopy construction and utilizes high strength carbon fibre.

3.   Front has a boxed section for added crash protection.

4.   Positive double action latch keeps canopy closed in accidents.

The effectiveness of secondary safety is proven by the many crashes the vehicles have had with only minor rider injuries and with minimal vehicle damage. No vehicles have DNF’ed through canopy damage.

Ease of rider entry and exit. In pit stops it is possible for a rider to exit on one side while the new rider is ready to enter on the other. An exhausted rider can virtually roll out of the vehicle. Pit attendants have full access to assist riders with drink bottle changes, headrest adjustment, seat belts, shoe cleats, etc. Very quick pit stops can be achieved.

Easy access to all parts of chassis for maintenance and repair. Rear wheel can be removed very quickly from the top. Top can be hinged right up to enable access to all front parts, crank, lights etc.

Ease of assembly and disassembly of vehicle. Chassis can be taken out with the removal of 5 fixing points and the disconnection of two electrical connectors. No part of the chassis has to be removed or disassembled.

Low cost construction. Mostly low cost materials can be used with only small amounts of high cost materials (Kevlar and carbon fibre) as in Reloaded. Shape is designed to make effective use of flat polycarbonate sheeting for side windscreens which is much simpler and less expensive than convex windscreens. The small size keeps the cost of making the front screen convex to a minimum (Fill).

Achievement Record  

We believe our success in many races over the past five years is partly due to the features of the canopy listed above. Considering Weeroona is a primary to year 10 college and many of our successes have been against older teams, our successes are quite outstanding.

2000 RACV Energy Breakthrough       Won Hybrid 2 class. Set fastest lap of event.

2001 RACV Energy Breakthrough       Won HPV class B on our first attempt in HPV’s

                                                   Won Hybrid 1 Open class and took hybrid line           honours.

                                                   Runners-up in Hybrid 2.

2002 RACV Energy Breakthrough       Runners up in HPV class B

                                                   Runners up in Hybrid 1 open class, set fastest lap.

           Runners-up in Hybrid 2, set fastest lap.

2003 Wonthaggi                             Won class B

2003 RACV Energy Breakthrough       Won HPV class B, completed trial in second place outright,      beaten only by one open class team.

                                                   Won Hybrid 1 Open class.

                                                   Won Hybrid 2.

2004 Wonthaggi                  Runners-up class B, completed most laps in class and set fastest lap of all vehicles in race.

2004 AIPP, Murray Bridge     Hybrid vehicle set fastest lap in practice to gain pole position. Won hybrid section of event.

2004 RACV Energy Breakthrough       Won HPV class B, completed trial in second place outright of all HPV’s, beaten only by one open class team. Set second fastest lap of race.

                                                   Won Hybrid 2.

2005 Maroondah Grand Prix        Won Seconday HPV, Primary HPV and Hybrid sections.

                                             Won line honours against all vehicles including several community class teams.

2005 RACV Energy Breakthrough       Second in HPV class B

                                                   Won primary HPV for small schools

                                                   Won Hybrid 1 Open class.

2006 Wonthaggi                              Runners-up class B, completed most laps in class.

2006 Maroondah Grand Prix       Won Seconday HPV, Primary HPV and Hybrid sections.

                                            Won line honours against all vehicles including several community class teams.

                                             Set fastest lap of all vehicles for race.

Other schools who have used our canopy have also been winners.

John Taylor

August 06