An excellent document describing and detailing the separation and jettison of the Forward Bay Cover during re-entry. The FBC needs to be jettisoned to expose the EDL systems for parachute deployment and upright bag inflation after splashdown. It is interesting how what initially seems like an easy task can become very complex and complicated, involving several subsystems and teams across numerous organizations.
A few interesting points from the document:
1. The design of the FBC has gone through 4 iterations since 2006, including a complete re-design in 2009. The re-design switched from the initial (and current) one piece FBC design to a 6 piece FBC that would be jettisoned via airbags. This design was later dropped due to low confidence levels, uncertainties and costs associated to testing. The design also failed to converge on a solution to balance FBC mass, jettison velocities and risk mitigation of the other EDL equipment.
2. Due to the flow characteristics around the CM during high speed re-entry and reverse flow wake is formed above the apex of the CM. The wake would often cause the FBC to reverse direction and travel back toward the CM after jettison (which is obviously undesirable) during simulations and testing. This phenomenon was also observed during Apollo CM Forward Heat Shield design and testing to the surprise of many engineers.
3. Due to dynamic loading of the FBC parachutes during deployment, a moment was sometimes produced about the Orion CM, causing the CM Apex to pitch forward during the brief time of free fall between the jettison of the FBC and the deployment of the drogue parachutes. Engineers were worried that this could cause the CM to completely flip over (with the apex pointing down), which would have catastrophic effects on the main chute deployment.