In the
present work we describe a methodology for the optimization of the re-entry
trajectory during the mission analysis phase. The methodology is based on
sequential optimization of the AoA and bank angle profile. Specifically, the
AoA profile is first optimized to produce a re-entry corridor large enough to
ensure the ability to react to off-nominal entry conditions while guaranteeing
a downrange capability sufficient to reach the terminal conditions at Terminal
Area Energy Management (TAEM) interface. Downrange capability is determined as
the difference between the downrange obtained with a minimum value of the bank
angle and the downrange obtained with a maximum value of the bank angle. Using
the optimized AoA profile, a reference trajectory is then computed inside the
obtained re-entry corridor via bank angle profile optimization. This
optimization is carried out with the goal of minimizing the distance of the
final trajectory point from TAEM interface while ensuring that all mission
constraints are satisfied. The advantage of this sequential optimization is to
allow designers to plan the reference or nominal AoA profile and explore the
capabilities of the vehicle in terms of entry corridor and mission downrange
flexibility. The methodology described in this Note is applied to a case study
concerning the re-entry mission of the FTB3 vehicle, a winged flying test bed
designed by Italian Aerospace Research Center (CIRA) for in-flight validation
of enabling technologies for atmospheric re-entry. The results indicate that
re-entry corridor optimization allows taking advantage of corridor
capabilities thus improving mission flexibility.