Sept 25, 2016 - Polycarbonate Windshield Forming

This is U of T's method for forming a polycarbonate canopy without heat:

Prototyping labs with vacuum forming technology will also be able to help you. However, if you don't have either of these types of companies nearby, but have access to a negative canopy mold, carbon fibre/epoxy, and 1/8" polycarbonate, I can tell you a method that Blue Sky used on the past 4 vehicles that works very well and easy to do.

EDIT: Non-thermoforming method (no heat)

Plan out where your windshield will be in CAD (you need 1 -1.5 inch of extra bonding surface all along the edge of windshield.
Cut 2 copies of polycarbonate windshield screen (including the bonding surface)
Hot glue one copy of the polycarbonate windshield screen to the surface of the mold (You're going to throw this one out) and put mold release over the polycarbonate in the mold.
Layup over the polycarbonate onto the mold. (Creating a lip that the real good windshield will sit on.)
Pop it and cut out the holes for the windshield screen (I suggest you make sure you leave some material that connects the bottom half of the carbon to the top half of carbon to ensure shape doesn't deform)
Put the good polycarbonate windshield into the mold and put even layer of epoxy onto the bonding area to fix it (you can put vacuum on it while it's curing, but make sure you put flashbreaker tape along the edges of the bonding surface so you don't get epoxy all over your canopy)

Sept 10, 2016 - Dynamometer testing trip

On Sept 10, 2016, Minghao and 4 U of T Blue Sky members travelled from Toronto to Midnight Sun's bay in order to use our dynamometer to measure efficiency curves for their motors. A lot of knowledge was shared during the trip, although in the end U of T's dynamometer tests could not be completed due to suspected damage to our dyno's torque sensor. The notes below are a summary of key insights from Minghao's conversations with Frank Gu (PM) and Sean Doughty (Chief Engineer) during the return trip to Toronto.

Building a car in 2 months

According to Frank, U of T's design and manufacturing process is designed to only take one school year to finish. At the time of the trip, U of T had just returned from ASC 16 with the car inherited from the previous team. U of T's plan is to complete a total design for their next vehicle by November and begin machining and aerobody manufacturing before winter break.

This process involves heavy reliance on machining sponsors for the manufacturing of most metal components and Frank claims typical achievable lead time is 3 days. Their team has at times taken part patterns directly to shops and asked for machining services. In some extreme cases, unconventional methods that may not be considered politically correct are employed.

Frank claims that during manufacturing the team has as many as 12 to 15 team members working 12 hour days continuously each week, often resulting in skipped classes. The total manufacturing process is expected to be complete by May, and the team intends to race their car in FSGP 2017.

Some of these strategies are not realistically achievable for Midnight Sun due to Waterloo's co-op system, as well as the impracticality of regularly skipping classes for many core members. However, it does demonstrate the fact that a car can be fully completed from start to finish in only 8 months, while still producing a reasonably reliable vehicle.

Blue Sky's MSXI, "the build cycle that isn't talked about"

From 2007 to 2011, U of T's team spent 4 years building their Azure challenger car. The team that designed the car ran into design issues and consequently ended up passing the task of completing the car to a small group of new members and alumni. These members, led by Paul Park (recently ASC 16 race official), put a significant amount of work into completing the vehicle and took it to WSC 11. In Darwin, Australia, they tried unsuccessfully to fix/finish most parts of the car and were forced to trailer most of the race, placing 24th overall. According to Frank, team morale after returning from the race was worse than after the death of their driver in a solar car highway accident many years prior.

The build team that completed Azure were driven by the failures of this vehicle and their desire to design a vehicle of their own. This team then designed and manufactured the B-7, which competed in WSC 13 and finished 8th overall, and 2nd out of North American teams in the challenger class. Azure is often described as the embodiment of "how shitty an engineering design can be" and is used to remind members to adhere to good design principles.

Azure and MSXI demonstrate the importance of having a sustainable team cycle that balances the development of new vehicles and current members with the bring up and integration of new members, all while keeping a healthy budget. Interestingly, at the time of this writing (Sept 11, 2016) U of T is in an extremely similar financial position as our team.

Sept 4, 2016 - Minghao's visit

On September 4, 2016, Minghao visited U of T's Blue Sky Solar Car Team. This page documents some key points in their composite process explained by Sean Doughty, their Chief Engineer.

Mounting to composite panels

When they want to mount to composite panels (CF - honeycomb core - CF) using fasteners, they will cut out an area of their core material and replace it with a metal plate. Holes are then drilled through the entire piece after it has cured to achieve the desired mounting points. This is ideally designed as part of the panel itself and implemented during the initial layup of the panel, however they are also able to add an arbitrary mounting point to an existing panel by cutting out one side and removing the core, inserting the metal, and laying up CF over top (weaker than doing it during the initial manufacturing of the panel).

This technique was developed with help from their team alumni after they ran into issues with their suspension ripping out of their car during races. Sean explains that attaching fasteners directly to composite panels with a honeycomb core will crush the panel, compromising its structural integrity.

Unibody structure

The main aerobody for U of T's most recent car was constructed using many separate MDF molds with interior faces soaked in epoxy resin. The external walls of their aerobody are extremely thin (~3 mm) as the majority of the structural strength for their car comes from a composite chassis formed with intersecting composite bulkheads. These bulkheads use thicker honeycomb core material similar to that used for MSXI's monocoque.

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