Engineering topics
Publications and source records attributed to Madsen, Jennifer.
Presentation on the European Service Module mission description, propulsion subsystem, and propulsion and guidance navigation and control interface requirements. The content focuses on the updates to these areas between Constellation and the Multi-Purpose Crew Vehicle.
The manual piloting requirements specified under the NASA Constellation Program involved Cooper-Harper ratings, which are a qualitative and subjective evaluation from experienced pilots. This type of verification entails a significant investment of resources to assess a completed design and is not one that can easily or meaningfully be applied upfront in the design phase. The evolution of the Multi-Purpose Crew Vehicle Program to include an independently developed propulsion system from an international partner makes application of Cooper-Harper based design requirements inadequate. To mitigate this issue, a novel solution was developed to reformulate the necessary piloting capability into quantifiable requirements. A trio of requirements was designed which specify control authority, precision, and impulse residuals enabling propulsion design within specified guidance and control boundaries. These requirements have been evaluated against both the existing Orion design and the proposed ESA design and have been found to achieve the desired specificity. The requirement set is capable of being applied to the development of other spacecraft in support of manual piloting.
One of the most demanding tasks that must be performed by the Space Shuttle flight crew is the process of determining whether, when and where to abort the vehicle should engine or system failures occur during ascent or entry. Current Shuttle abort procedures involve paging through complicated paper checklists to decide on the type of abort and where to abort. Additional checklists then lead the crew through a series of actions to execute the desired abort. This process is even more difficult and time consuming in the absence of ground communications since the ground flight controllers have the analysis tools and information that is currently not available in the Shuttle cockpit. Crew workload specifically abort procedures will be greatly simplified with the implementation of the Space Shuttle Cockpit Avionics Upgrade (CAU) project. The intent of CAU is to maximize crew situational awareness and reduce flight workload thru enhanced controls and displays, and onboard abort assessment and determination capability. SAFM was developed to help satisfy the CAU objectives by providing the crew with dynamic information about the capability of the vehicle to perform a variety of abort options during ascent and entry. This paper- presents an overview of the SAFM application. As shown in Figure 1, SAFM processes the vehicle navigation state and other guidance information to provide the CAU displays with evaluations of abort options, as well as landing site recommendations. This is accomplished by three main SAFM components: the Sequencer Executive, the Powered Flight Function, and the Glided Flight Function, The Sequencer Executive dispatches the Powered and Glided Flight Functions to evaluate the vehicle's capability to execute the current mission (or current abort), as well as more than IS hypothetical abort options or scenarios. Scenarios are sequenced and evaluated throughout powered and glided flight. Abort scenarios evaluated include Abort to Orbit (ATO), Transatlantic Abort Landing (TAL), East Coast Abort Landing (ECAL) and Return to Launch Site (RTLS). Sequential and simultaneous engine failures are assessed and landing footprint information is provided during actual entry scenarios as well as hypothetical "loss of thrust now" scenarios during ascent.