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This article is for those who aren't on aeroshell who want a general idea on how our layups work so they can come in feeling prepared Hi! I'm Elizabeth (Maylin) Rawson, the 2023 Aeroshell lead. I created this to give a general overview of how the layup process works! This is aimed towards new members/people not on aeroshell to get them onboarded to the layup process.

Background

The 2022-2024 aeroshell is made up of 3 major parts: 

• Top shell
• Bottom shell
• Canopy

Materials

There Composites are made of two types of materials composites are made from. Flexible materials: flexible fiber and a hard matrix. These combine to make a strong material.

• Fiber (fabric)
  • Fiberglass: heavy and flexible
    • Our molds are made of this 
  • Carbon Fiber: relatively strong for how lightweight it is
    • Our car is made of this
  • Kevlar: very strong, shatterproof and fireproof
    • Our canopy is made of this
• Matrix (epoxy resin)
  • Resin is made from mixing one resin with a hardener according to the ratio specified on the resin packaging (typically a 5:1 ratio of resin to hardener)
    • When the two are mixed a chemical reaction occurs and the viscous liquid turns into a hard solid which reinforces the fabric
    • We have a limited time to work with this (this is called pot life) so work fast
• We also use foam to reinforce the structure of the layupcomposite

Ply is the amount of layers of each fabric. The person in charge of the shift will tell you how much ply to do

• Topshell is made of 2 ply of carbon fiber, a layer of foam, and 2 ply of carbon fiber
• Bottom shell is made of 6 ply of carbon fiber
• Canopy is made of 2 ply of carbon fiber and 2 ply of kevlar on the sides, and fiberglass on the very top dome

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• Wear a respirator because epoxy fumes are bad
  • LHR has communal respirators but if you are a germaphobe I recommend you buy your own. You need a respirator and filters
  • Respirator: https://www.amazon.com/3M-Respirator-6200-Respiratory-Protection/dp/B007JZ1N00/ref=sr_1_4_pp?c=ts&refinements=p_89%3A3M&s=hi&sr=1-4&ts_id=2257619011
  • Filters: https://www.amazon.com/Respirator-Cartridge-Particulate-Effective-Particulates/dp/B0BM99H1CC/ref=sr_1_1_sspa?s=hi&sr=1-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&psc=1
• Wear gloves and your worst clothes to keep any epoxy from getting on yourself. It is very hard to get off
  • If you do get epoxy on yourself, use acetone to get it off. Use this very sparingly and wear a respirator when you are exposed to acetone.

Roles (Easiest to hardest)

• Scrapers: scrape out excess epoxy and make sure the carbon fiber is flush to the surface of the mold
  • 6-8 people
• Bucket duty: mixes an adequate amount of epoxy and distributes it in a timely manner
  
  • 2-3 people
• Fabric duty: applies the fabric in the right area so there are no creases, tends to be more experienced members and/or people who cut the fabric
  
  • 4-5 people
• Overseers
  • 1-2 people

Step-by-step guide

Pre-Layup

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Layup: We want to build up fabric and resin around in a loop, going from adjacent area to adjacent area. We want the composite to be as smooth as possible, with no air bubbles.

1. Have 2 people mix a bucket of epoxy Use a scale mix resin and hardener according to the ratio specified on the resin
   1. Depends on the brand so read the label
2. Apply epoxy to the mold with a paintbrush in the size of the carbon fiber piece you are about to lay down
   1. Make sure the entire area is saturated with epoxy
3. Put the carbon fiber on the epoxied area and press it down very flat until it is flush with the mold
4. Apply more epoxy until every single bit of fabric is wet
   1. We the fabric to be wet but apply epoxy moderately. We do not want to waste any.
5. Use a flat scraper to scrape out any excess epoxy from the fabric
   1. Be gentle and firm at the same time.
      1. Try to hold the fabric down taut with one hand so it doesn't move around. 
      2. Scrape with medium pressure and be conscious that you do not alter the weave of the fabric, we want to keep that nice checkerboard pattern.
   2. Move excess epoxy into the next area we plan to add fabric on  
6. Repeat this process
   1. On all subsequent layers, tack down carbon fiber and let the resin from the prior layer soak in before you add excess resin. This prevents waste

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