the Personnel Launch System or pls is a
vehicle which could provide future
transport of people and small cargo to
and from low-earth orbit although not
presently approved for development the
pls is being designed to complement the
space shuttle and is being considered as
a future addition to the manned launch
capability of the United States in the
era of space station freedom and
subsequent missions of the space
exploration initiative it may be
important that the United States have an
alternate means of getting people and
small cargo to low-earth orbit and back
to designs being considered for pls
differ in their aerodynamic properties
and mission capabilities while the
Johnson Space Center's approach uses a
bi conic shaped capsule with the
parachute landing the Langley Research
Center's design designated the hl-20 is
a winged lifting body which could make
conventional runway landings on return
from orbit
unlike the space shuttle the PLS would
have as a design objective a launch
abort capability to safely recover the
crew during ascent predating and
influencing the design of the space
shuttle several lifting body aircraft
including the HL 10 were flown by test
pilots during the period from 1966 to
1975 over the past few years the hl-20
has undergone considerable analysis at
langley and has evolved into a mature
design with capabilities which
adequately satisfied the PLS design and
mission requirements a lifting body
spacecraft such as the hl-20
and the HL 10 shown here would have
several advantages over other shapes the
spacecraft would fly over large land
areas and the number of available
landing opportunities would be increased
wheeled runway landings would be
possible permitting simple
cost-effective precision recovery at
many sites around the world including
the Kennedy Space Center launch site
a primary mission of the PLS would be to
deliver passengers to the space station
freedom typically a space station crew
of eight will be delivered by a two
person pls flight crew with an overall
length of twenty nine point five feet
and span across the wingtips of 23.5
feet the hl-20 concept would be a much
smaller craft than the Space Shuttle
Orbiter and will fit within the payload
Bay of the shuttle with wings folded
using the extensive one tunnel resources
at Langley researchers compiled a
comprehensive aerodynamic and
aerothermodynamic database on the hl-20
concept spanning the entire speed range
which the PLS will flock several models
were built for testing the various
tunnels ranging from a 6-foot model used
for forces and moments tests at low
speeds to six-inch models used in
hypersonic test results have shown the
shape possesses good flying qualities
and all speed regimes computational
fluid dynamics or CFD codes have been
used at Langley to study flow field
characteristics of the hl-20
these advanced computational grid
techniques were used in conjunction with
when tunnel tests to study patterns of
flow field phenomena shock waves
stability and control and heating on the
windward and leeward surfaces of the
vehicle it was found that heating
predicted by this concept will be within
the limits of space shuttle based
high-temperature a reusable surface
insulation except at the nose where
shuttle bays carbon carbon will be
requirement
in addition to computer modeling of
vehicle controllability during entry a
flight simulator has been set up at
Langley to permit pilots to study the
final landing phase of flight starting
at 15,000 feet the simulation presents a
realistic view of the approach to a
runway landing using a sidestick
controller at a minimum of
instrumentation pilots including one who
flew the x-15 rocket plane and the
lifting bodies have demonstrated this
configuration to be controllable and
capable of pinpoint landings a
cooperative agreement between NASA and
North Carolina State and North Carolina
A&T universities led to the construction
of the full scale model of the hl-20 pls
for use in further research of this
concept with requirements furnished by
Langley University instructors and
students designed the research model
during their 1990 spring semester with
construction following during the summer
the research objectives of the hl-20
model are to assess crew ingress and
egress operations assess crew volume and
habitability examine fit checks of
various subsystems arrangements and
determine visibility requirements for
the crew during critical docking and
landing operations the model will be
moved to the Langley Research Center
where human factors or search will be
conducted later the model will be
located at the Johnson Space Center
where the research effort will involve
members of the astronaut corps who will
evaluate the hl-20 for operations
efficiency the Langley Research Center
has defined a lifting body pls for a
sure advanced s2 space for future u.s.
space missions this reusable vehicle
designated the hl-20 has been designed
for safe and reliable operations
improved operability maintainability and
affordability and has a potential for
reducing lifecycle cost associated with
placing people in orbit