(Georgia Institute of Technology, 2006-08)
Alemany, Kristina; Wells, Grant William; Theisinger, John; Clark, Ian G.; Braun, Robert D.
Entry, descent, and landing (EDL) is a multidimensional, complex problem, which is
difficult to visualize in simple plots. The purpose of this work is to develop a systematic
visualization scheme that could capture Mars EDL trades as a function of a limited number
of variables, such that programmatic design decisions could be effectively made with insight
of the design space. Using the Mars Science Laboratory (MSL) as a basis, contour plots have
been generated for key EDL figures of merit, such as maximum landed elevation and landed
mass as a function of four input parameters: entry mass, entry velocity, entry flight path
angle, and vehicle L/D. Additionally, sensitivity plots have been generated in an attempt to
capture the effects of varying the fixed input parameters. This set of EDL visualization data
has been compiled into a Mars EDL handbook to aid in pre-phase A design space
exploration and decision making.
(Georgia Institute of Technology, 2006-08)
Clark, Ian G.; Braun, Robert D.; Theisinger, John; Wells, Grant William
This study investigates the advantages and feasibility of using ballutes for Earth entry at
lunar return velocities. Using analysis methods suitable for conceptual design and assuming
a CEV type entry vehicle, multiple entry strategies were investigated. Entries that jettison
the ballute after achieving low Earth orbit conditions were shown to reduce heating rates to
within reusable thermal protection system limits. Deceleration was mitigated to
approximately four g's when a moderate amount of lift was applied subsequent to ballute
jettison. Primary ballute size drivers are the thermal limitations and areal densities of the
ballute material. Performance requirements for both of those metrics were generated over a
range of total ballute system masses. Lastly, preliminary investigation of a lower mass cargo
variant of the CEV allowed for additional reduction of ballute system mass. However,
ballute system mass as a percentage of the total entry mass was shown to be relatively
independent of the entry mass.
(Georgia Institute of Technology, 2005-05)
Clark, Ian G.; Francis, Scott R.; Otero, Richard E.; Wells, Grant William
On the heels of the recent success of the X-Prize, sub-orbital space tourism is nearly a
reality. Though the requirements are significantly tougher, orbital space tourism is the next
logical step. The Reusable Exploration Vehicle (REV) concept is an economically feasible
design capable of making this next step. Centered around a lenticular lifting body, the REV
concept relies on commercial launch vehicles to reduce DDT&E expenditures. Capable of
ferrying five passengers and one crew member for three orbits, the REV is shown to be
capable of keeping maximum debt exposure to less than $250M while attaining an IRR of
70% with an estimated market capture of 66%.