The video discusses the bodywork of the Lotus Evora, focusing on why fiberglass was chosen over metal, the history of fiberglass, and the cost of replacement parts (0:30).
History of Fiberglass and Composites:
Modern fiberglass was accidentally discovered in 1935 by Daryl Kleist while working for Corning Glass.
DuPont later patented polyester resin, leading to the creation of the first composites.
During World War II, Germans furthered research, and British intelligence agents stole the secrets, leading to fiberglass components appearing on allied aircraft for radar covers.
The Boeing 787 Dreamliner is mostly made of composite materials, showing the progression of composites in the aircraft industry.
Fiberglass in Car Manufacturing:
Colin Chapman of Lotus realized fiberglass would be a good material for cars.
The first production fiberglass car was the Glasspar G2 in 1949.
Chevrolet introduced the Corvette C1 with a fiberglass body in 1953.
Lotus introduced their first fiberglass car, the Type 14 Lotus Elite, in 1957, which was one of the first fiberglass monocoque cars.
Advantages of Fiberglass for Lotus:
Fiberglass is good for low-volume manufacturing, and shapes can be changed more easily compared to expensive steel pressed panels.
Fiberglass Manufacturing Processes for Evora Panels:
Open Mould Process: Involves making a mold, waxing it, applying a gel coat, laying fiberglass mat, and impregnating it with resin.
Vacuum Assisted Resin Injection (VARTM): Pioneered by Lotus for the X180 Esprit bodies, using male and female molds with a vacuum to pull in resin.
Injection Compression System Resin Transfer Molding (ICSRTM): Used for external panels where quality is a priority. Glass fiber mat is laid in a heated closed mold, polyester resin is injected, and the molding is compressed. Panels produced this way include:
Front Clamshell Outer: Costs around £4,000 to replace.
Rear Clamshell Outer: Costs around £4,000 to replace.
Body Sides: A large panel, replacement takes 35 hours and costs around £1,800.
Tailgate Inner.
Roof Panel: Standard composite costs around £1,050, while carbon fiber is £3,000.
Door Inner.
Windscreen Frame: Costs about £1,500 to replace.
Resin Transfer Molding (RTM): Uses a liquid thermostat resin to saturate a fiber preform in a closed mold. Panels include:
Battery and Boot Box and Clamshell Reinforcement Panel.
Rear Bulkhead: Costs around £700 to replace.
Sheet Molded Composite (SMC): A plastic film laid on a moving bed with polyester resin and chopped fiberglass, then compacted and fed onto a roller. Panels include:
Tailgate Outer: Standard SMC costs around £1,400, and a carbon fiber version is about £3,500.
Door Outer Panels: Come with an extruded alloy beam for side intrusion protection.
A Post Panels and Front Access Hatch: SMC A post is around £400, carbon fiber is £795. SMC front access hatch is around £460, carbon fiber is £1,050.
Reinforced Reaction Injection Molding (RRIM): A mixture of polyurethane resin and milled glass injected into a closed mold. Used for front and rear bumpers, which are flexible and forgiving of small impacts. Standard bumpers cost around £1,000, and carbon fiber versions are about £3,500.
Challenges and Characteristics of Lotus Bodywork:
Fixings can be seized and break.
New panels may not fit perfectly and require adjustment.
Panels can have various different thickness shims that fall out.
A multitude of different size fixings and washers are used.
Lotus cars are hand-built, leading to inconsistencies that only humans can adapt to.
Lotus's Future:
The Evora is seen as an underrated sports car with a strong chassis and good dynamics.
Concerns are raised about Lotus's future with mass production in China and the potential loss of its hand-built heritage.
The video emphasizes the need for improved build quality, expanded dealer networks, and support for older models and enthusiast dealers.
Source: https://www.youtube.com/watch?v=s1d0pbnD2fE&t=205s
Source: https://www.youtube.com/watch?v=s1d0pbnD2fE&t=205s
