B8
Paper #6043
Disclaimer—This paper partially fulfills a writing requirement for first year (freshman) engineering students at the University
of Pittsburgh Swanson School of Engineering. This paper is a student, not a professional, paper. This paper is based on publicly
available information and may not provide complete analyses of all relevant data. If this paper is used for any purpose other
than these authors’ partial fulfillment of a writing requirement for first year (freshman) engineering students at the University
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APPLICATION OF LIFTING BODIES FOR SPACEFLIGHT
Azalea Bisignano, azb19@pitt.edu, Mena, 6:00, Zachary Gubatina, zag12@pitt.edu, Mena, 4:00
Abstract—A lifting body design is an airframe design such
that the main fuselage body of a flying craft provides lift. This
is in contrast to conventional aircraft designs that rely on
wings for the production of the majority of lift. General
advantages of lifting body designs include improved loadcarrying ability and lowered air drag due to its aerodynamic
qualities. The most recent application being considered for
lifting body designs is spaceflight, with regards to its reentry
characteristics and resultant overall vehicle geometry.
As interest in spaceflight increases, so must the ease of
access to orbit. The opening of a new frontier serves to expand
current industries and potentially the creation of new
industries that help further humanity. By creating a spacecraft
which can easily be reused, monetary costs can be further
lowered, and a safe, effective vehicle creates a positive public
image.
Currently, the industries with uses for reentry spacecraft
are limited to scientific fields, and even then, the capability to
perform scientific work is limited. However, as access to space
increases, the development of a safer, more efficient, and more
comfortable passenger spacecraft increases in importance.
Taking all of the factors of reentry from space, a lifting body
design provides many benefits for such a spacecraft.
Key Words—aerodynamics, lifting body, reentry, spaceflight,
thermodynamics
NASA Ames Research Center. The eight lifting-body
configurations that were flown over this period “varied
tremendously from the unpowered, bulbous, lightweight
plywood M2-F1 to the rocket-powered, extra-sleek, all-metal
supersonic X-24B” [2]. The program’s 222 flights and 20,000
hours of wind-tunnel tests have been well documented in about
100 technical reports. Despite this seemingly intensive
research, until recently, documentation of lifting body research
has solely consisted of that generated from NASA’s lifting
body program which officially ended in 1975.
Although the program officially come to a close when
NASA as a whole decided to go with a ballistic capsule as
opposed to a lifting reentry vehicle exploration of the concept
of lifting bodies “has had highly significant influence on
decisions guiding the course of events in the space program”
as exemplified by the Shuttle which reentered Earth’s
atmosphere as an unpowered glider and continues “to have a
significant impact on the design and technology of current and
developing vehicles. In the 1980s and 1990s, the lifting-body
legacy went international as Russia, Japan, and France began
to design and test lifting bodies” [2]. It is only recently that
the concept of a lifting body design started to be considered for
spaceflight. “During the early 1990s the United States of
America began to develop lifting-body designs for use as
space-station transports as spacecraft, and as a future
replacement of the [now recently retired] Space Shuttle” [2].
INTRODUCTION TO LIFTING BODIES
WHAT ARE LIFTING BODIES
ORIGINS OF THE LIFTING BODY CONCEPT
Research and the development of lifting bodies first came
about in the 1960s and beginning of the 1970s following the
investigation of the re-entry of missile nose cones. Engineers
at the National Aeronautics and Space Administration (NASA)
“determined that a blunt nose cone was a desirable shape to
survive the aerodynamic heating associated with re-entry from
space…[B]y slightly modifying [the] symmetrical nose cone
shape, aerodynamic lift could be produced” [1]. This
discovery was incredibly significant as it enabled controlled
flight of the modified shape rather than the ballistic trajectory
that was characteristic of missiles designed up until that point.
During this time, lifting body vehicles were flight-tested at the
NASA Flight Research Center which is now known as the
University of Pittsburgh Swanson School of Engineering 1
Submission Date 2016-03-04
A lifting body is an airframe that is designed such that the
shape of the flying craft’s fuselage (main body) is what
provides lift as opposed to its wings. “Lift is a mechanical
force generated by a solid object moving through a fluid” [3]
and is in direct opposition of the force of gravity, which is
commonly known as weight, acting on the solid object.
Because air is a substance that deforms under an applied shear
stress, it is classified as a fluid. Therefore, any aircraft in flight
can be considered as a solid object moving through a fluid and
consequently requires lift to counteract the gravity acting on it
in order for it to remain airborne. This force acts through the
center of pressure (average location of pressure) of an aircraft
and is directed perpendicular to the flow direction. Lift cannot
occur without fluid or motion because it is generated by the
difference in velocity between the solid object and the fluid
due to the interaction and contact between the two. Although
Azalea Bisignano
Zachary Gubatina
lift is generated by every part of a flying craft, “most of the lift
on a normal airliner is generated by the wings” [3] unlike that
of the unconventional design of a lifting body.
Other forces which act on all aircraft, whether they be
winged or of a lifting body configuration include drag and
thrust. Drag is a mechanical force that is generated by a solid
object moving through a fluid and is directed along and
opposed to an aircraft’s motion through the air. Just like lift,
drag is generated by every part of the aircraft including the
engines and acts through the flying machine’s center of
pressure. The magnitude of form drag is dependent on the
component force applied by local pressures on the body
opposing motion. Another type, called ram drag, is produced
when free stream air is brought on board, as demonstrated by
jet engines that function on a cycle of intake, compression,
combustion, and exhaust. Cooling inlets on said engines to
prevent them from overheating are another source of this type
of drag. The final type of drag, while a main concern for
winged aircrafts, occurs to a much lesser extent on a lifting
body configuration. This type of drag, induced drag, only
occurs on finite lifting wings as drag due to lift. Because lifting
body designs have much smaller wings, mainly for
maneuverability of the vehicle and not as a source of lift, their
wings do not have as much of an increase of a local angle of
attack which leads to less of an induced flow of the wing tip
vortex and subsequently a smaller downstream-facing
component of the aerodynamic force acting on the vehicle
(drag).
reentry qualities. Other benefits may include a construction
conducive to spacious internal cargo volume. While lifting
body crafts can provide benefits over other designs, design of
such a spacecraft involve computations of “aerodynamic
performance, aerodynamic heating, capacity utilization and
stability” [4]. Optimization algorithms have been developed by
researchers for this purpose.
The reduction of drag and weight by minimizing
extraneous protruding structures is highly important for a
reentry vehicle. Because a lifting body vehicle efficiently
makes use of its total construction weight so that its fuselage
provides the majority of the lift, only short protruding winglets
may be required to mount control surfaces. Control surfaces
are still required by a spacecraft to provide it with sufficient
maneuverability in the thicker atmosphere once in its landing
phase. Regardless, the amount extending from the main body
is significantly less than on a non-lifting body design. Reduced
wing structure also reduces friction and heating [5].One of the
major beneficial reentry qualities of a lifting body design is its
ability to handle the thermal loads of atmospheric reentry. The
Space Shuttle was an early design, designed during a time
when data on reentry qualities were mostly limited to bluntbody craft. In the years that followed, research into lifting body
reentry vehicles increased, improving knowledge about the
interaction of spacecraft geometry and the aerodynamic factors
at reentry velocities.
In one such testbed, the Pre-X, the aerothermodynamic
qualities of a lifting body shape and resultant thermal
protection system (TPS) arrangement were tested [6]. This
ESA research project, conducted in the late-2000s by CNES
(French Space Agency), drew upon data gained from
numerous projects before it, including NASA’s X-series and
the Space Shuttle as well as Russia’s BOR-4, BOR-5, and
Buran. The Pre-X vehicle was designed to gather data in the
hypersonic range, between Mach 5 and 25. This speed range
encompasses the most intense stage of reentry for a space
vehicle, occurring right on entry of the atmosphere. Data
gathered displayed the thermal advantages in the
aforementioned blunt-nose shape, and control was sufficiently
provided by two elevons on the rear of the test vehicle.
The ESA’s IXV which came afterwards inherited qualities
from the Pre-X and other experimental programs. It was
intended to further test concepts of lifting body reentry
vehicles. From these experimental programs, more data was
collected concerning the interactions of craft geometry and air
flow and resultant thermal loads, alongside data for angle of
attack and control surface functionality at such velocities. The
IXV was designed with two winglets extending from the side
to provide in-atmosphere maneuverability.
EXPANSION OF TECHNICAL DETAILS
FUNCTIONS AND FEATURES OF LIFTING BODIES
The basic design of a lifting body vehicle can be described
as such: “Compared with the traditional layout of aircraft,
lifting body configuration does not have the major componentconventional wings; it produces lift force by using the threedimensional design of the wing-body fusion instead” [Huang].
Advantages are described as “not only eliminate the additional
torque of the fuselage and other parts, but also eliminate the
interference between wings and fuselage, thus a higher liftdrag ratio will be obtained to improve [the] vehicle’s
performance” [4].
In the area of spaceflight specifically, a “lifting body is
considered promising for such re-entry due to its favorable
aerodynamic characteristics at high angle of attack” [5]. The
general design of a lifting body spacecraft can be
geometrically described as “blunt-nosed, half-cone … without
the main wing structure seen on most conventional aircraft”
[5]. The flattened nose cone is stated to produce lift and
enhance stability.
To reiterate, unlike conventional aircraft, a lifting body
produces a significant portion of its lift using through the
aerodynamic properties of its main fuselage body geometry
instead of wings. From the resultant geometry stem a number
of benefits. The main benefit manifests in the form of favorable
ADVANTAGES OF LIFTING BODIES
In 2011, America and the world saw the retirement of
NASA’s shuttle fleet. While the Space Shuttle was used to
transport astronauts to and from the International Space Station
(ISS), this vehicle design had incredibly limited landing
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Zachary Gubatina
capabilities in that it was only able to land on select runways
that had sufficient length to accommodate for the distance
required for the Shuttle to come to a complete stop once its
wheels touched down at speeds of over 200 miles per hour. In
comparison, a lifting-body spacecraft recovery vehicle, with
the addition of a large gliding parachute, could potentially have
landing speeds of as low as 40 miles an hour, which opens up
the potential for both off-runway landings and accessibility of
any runway designed to accommodate jet aircraft landings
around the world [2]. The drastic increase in the number of
landing opportunities suggests a decrease in the risk associated
with missions to space because an increase in plausible landing
sites leads to an increase in the likelihood of a safe and
successful landing should anomalies during a mission require
an abort.
According to “Principles of Clinical Medicine for Space
Flight,” a book edited by Michael R. Barratt and Sam Lee Pool,
“Lifting body spacecraft are considered to have several
advantages over other vehicle types….Acceleration loads
during [re]entry [into the Earth’s atmosphere] may be limited
to about 1.5G[, a quality] considered important when returning
ill, injured, or deconditioned space station crewmembers to
Earth” (Barratt). The safety of astronauts on a mission is of
paramount concern to everyone including but not limited to the
engineers designing the spacecraft, congressmen whom are
instrumental in deciding on the budget of governmentally
funded space agencies, and the general public. The engineers
have an added investment in the safety of the astronauts
utilizing their spacecraft due to the engineering codes of ethics
that they as engineers are required to practice under which
include “hold[ing] paramount the safety, health, and welfare of
the public [of which astronauts are a part of] in performance
of their duties” [7].
A misconception regarding “the lifting fuselage concept is
that the aspect ratio of the design is very low...there[by]
lead[ing] to high induced drag” [8]“The high aspect ratio [of
a] conventional [aircraft] design [supposedly has a] lower
induced drag because the effect of the wing tip vortices is
proportionally less: as air escapes from the higher pressure
underside of the wing to the upper surfaces, it pushes down on
the upper surface with consequent loss of lift. With a high span
wing, the wing tip vortices affect a smaller proportion of the
total surface area of the wing and therefore induced drag is
supposed to be less” [8]. Despite this reasoning, aspect ratio
does not necessarily predict drag which is instead dependent
on the Wetted Aspect Ratio: the “wing span squared divided
by total wetted area” [8]. Dr. M Watter discovered in his
evaluation of the advantages of the Burnelli lifting fuselage
that such an aircraft configuration leads to weight saving and
stability advantages. These advantages result from a lifting
body’s shortened wingspan as the aircraft does not have to rely
on aforementioned wings to produce lift. Shorter, and thus,
smaller, wings translates to less material required for the wings
and more importantly, a lighter aircraft with the same
capabilities and payload capacities as a conventional winged
craft. The implications of this discovery include the realization
of a less expensive, more fuel efficient spacecraft that has a far
superior load-carrying capability as opposed to the capsule and
glider designs which have been consistently relied on up to
date. The stability advantages result from the fuselage having
straight angular sides which “prevent cross flow of air from the
higher pressure underside to the lower pressure upper surface”,
thereby causing the fuselage to function as winglets (end plates
on the tips of conventional wings). In comparison, other
aircraft configurations employ “various curved blends to
merge the top and sides of the fuselage into the wings” [8].
Other advantages of a lifting fuselage configuration include a
simpler structural analysis of said design and also a greater
chance of survival upon a crash landing because it does not
have a conventional cylindrical fuselage and therefore will not
crumple or buckle when subjected to a compressive or shear
load.
The lack of a main wing structure in a lifting body
configuration also leads to less friction and the resulting
heating [9]. This is important because it signifies that a lifting
body vehicle requires less heat shielding to adequately protect
the vehicle during re-entry through the Earth’s atmosphere. A
capsule design or the Space Shuttle reached temperatures of
several thousand degrees Fahrenheit during the re-entry stage
while a lifting body design undergo less extreme temperatures
upon return to Earth. This phenomenon is a result of a lifting
body’s blunted nose which has the ability to more rapidly
dissipate the reentry energy through a large shockwave than
the NASA’s Space Shuttle or the Russian Soyuz [4].
LIFTING BODIES AND CURRENT
SPACEFLIGHT
INTERNATIONAL RESEARCH OF LIFTING BODIES
The Japan Aerospace Exploration Agency (JAXA) has also
recently begun to conduct tests on a subscale lifting-body
reentry vehicle. Their program is called the Lifting Body
Flight Experiment (LIFLEX) and its aim is to develop
technology for a future spaceplane. In 1996, the HYFLEX
lifting body was launched into a sub-orbital trajectory in order
to investigate hypersonic flight in the upper atmosphere.
Another design, “[t]he winged ALFEX was drop-tested several
times...to demonstrate automatic landing of a re-entry vehicle”
which was then followed up by an unpowered transonic drop
test of the subscale vehicle [10]. JAXA reports that their
wingless lifting body (LIFLEX) while having “inferior flight
performance in the atmosphere, has the advantages of lower
heating during re-entry and greater payload capacity” [10].
JAXA’s statement that “[b]lunt lifting bodies have poor lift-todrag ratios...making it difficult to maintain stability and
controllability at low speed[s]” is in direct disagreement of Dr.
Watter’s evaluation of Bernoulli’s lifting body and other
sources arguing that lifting bodies provide greater stability due
to their straight edged fuselage as compared to the
conventional cylindrical fuselage.
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Azalea Bisignano
Zachary Gubatina
gentle runway landing” [12] This variation is designed to be
optionally piloted and has the option of an attachment of a
disposable cargo module which would greatly increase the
amount of cargo (both pressurized and unpressurized) that can
be carried. The Dream Chaser Space System on the other hand
is a crewed spacecraft whose purpose is to transport crew to
and from the ISS. Therefore, this variant includes an
environmental control, life support system, seating for a crew,
and windows for crew visibility. Although the lifting body
research conducted by NASA during the 1960s and early
1970s was focused on airplanes constrained to Earth’s
atmosphere and not spacecraft, engineers at Sierra Nevada
definitely leveraged the knowledge gained from NASA’s
lifting body program and applied it as an integral building
block when designing the Dream Chaser.
The European Space Agency (ESA) has carried out launch
tests on their Intermediate eXperimental Vehicle (IXV) this
past year. The mission of the IXV is to test cutting-edge
system of a lifting body configuration and hopefully provide
Europe with independent reentry capability which to date, they
do not have [11]. Unlike JAXA’s vehicle, the IXV‘s design
allows for high controllability and maneuverability for
precision landing. The ESA is planning a newer vehicle the
Programme for Reusable In-orbit Demonstrator in Europe
(PRIDE). It was approved in late 2012, and incorporate
features resulting from IXV testing.
The Russian Space Agency’s version of a lifting body
spaceplane was designed in 2006 as a possible replacement of
the currently used Soyuz as a means of transportation to and
from the ISS. This new design, if implemented, would greatly
reduce the amount of g’s experienced by its occupants as
opposed to the number of g’s they experience in the Soyuz
capsule. Due to a lack of funding, the project has unfortunately
been indefinitely postponed, leaving cosmonauts with no other
transportation options other than the Soyuz.
FUTURE OF LIFTING BODY
TECHNOLOGY
IMPORTANCE OF DEVELOPMENT
RECENT DEVELOPMENTS FOR COMMERCIAL
APPLICATIONS
Spaceflight may seem out of the realm of relevant subject
matter when concerning the everyday person. However, this
can be attributed to how out of reach it is and low everyday
recognition. It is a field unfamiliar to many, but a brief
overview of the current industry may help understanding in
how advancement in spaceflight technology helps everyday
people.
Although it may seem like ventures into space may be a
marginal concern compared to other engineering fields with
easily visible, realistic effects here on Earth, benefits from
innovations in the aerospace industry actually have multiple
practical benefits for people on the ground. At times, it may
seem like the only things happening in space are experiments
and explorations of deep space, but the space industry is much,
much wider than just scientific fields. For every publicized
launch of a scientific mission such as a probe or telescope, or
even scientific discoveries on worlds far away, there are
numerous launches of satellites intended for communication,
weather monitoring, GPS, and other functional purposes.
These are only the current, everyday benefits people enjoy
from innovations in space travel. The space industry will
doubtlessly continue to expand, possibilities of which may
include space tourism, asteroid mining, or space colonization.
With those details expanded, the detail that goes into space
operations is incredibly complex, relying on the interaction of
numerous components. Each component in a space launch has
its own factors which contribute to the overall operation. A
reentry vehicle is one such component, and it “can be studied
through different physical domains linked together, owing to
the entire system or sub-systems” [Pre-X]. The development
of improved reentry vehicles is parallel to advances in rocket
technology and other space-related technologies. The article
continues by stating that “the interdependence of one system
with respect to another is very strong: the modification of one
Sierra Nevada Corporation’s (SNC) Space Systems,
specifically the Space Exploration Systems sector, has recently
partnered “with NASA as part of the Commercial Crew
Program to design and build a commercial system capable of
transporting crew and cargo to and from low Earth orbit
(LEO). Their design, named the Dream Chaser incorporates
lifting body concepts into its airframe and therefore is one of
the major recent developments in the field of lifting body
design. “The Dream Chaser [s]pacecraft [a]irframe [f]eatures
[i]nclude a lifting body spacecraft capable of autonomous
launch, flight and landing; high reusability; low 1.5 g
atmospheric entry throughout the entire flight profile, gentle
runway landing on any compatible commercial runway, both
in the United States and internationally; immediate access to
crew or cargo upon landing; all non-toxic consumables,
including propellants; [and the] ability to perform an ISS
propulsive re-boost when docked” to the International Space
Station [12]. Never before have engineers been able to design
a spacecraft in which all consumables are non-toxic including
the propellants. Highly toxic consumables that have the
potential of having an incredibly negative effect on the
environment have always been a component of previous space
going vehicles, thereby making the Dream Chaser more
environmentally friendly than previous modes of
transportation to space.
Sierra Nevada Corporation has developed two variations of
the Dream Chaser to accommodate for the needs of different
missions although both share the same airframe. The Dream
Chaser Cargo System variation “is designed to deliver up to
5,500 kg of pressurized and unpressurized cargo to the ISS
with the ability to conduct orbital disposal services and
responsively return pressurized cargo at less than 1.5 g’s to a
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Zachary Gubatina
[2] R. D. Reed. (1997). “SP-42200 Wingless Flight: The
Lifting Body Story.” NASA Dryden Flight Research Center.
(online article). http://history.nasa.gov/SP-4220/ch9.htm
element can imply effects all over the others. Some of these
subsystems have more functions at the same time: functional,
technological, experimental. The challenge consists in
designing a system capable to perform all these functions with
sufficient margins, safety and limited cost” [Pre-X].
To reiterate, development of one part of a system affects
the entire system as a whole. The entire system has a monetary
cost which is covered by a limited budget. By creating a
vehicle that is reliable, safe, and convenient for logistics, such
limited resources will be easier to allocate to other parts of a
space operation. And beyond a limited budget, there is the
physical constraint of payload weight able to be carried by a
launch vehicle. A lifting body reentry vehicle potentially has a
better ratio of weight to functionality than common blunt-body
crafts used today.
[3] Hall
[4] Y. J. Yongyuan, H. Chunping. (2010). “Shape Design of
Lifting body Based on Genetic Algorithm.” MECS. (online
article).
http://www.mecs-press.org/ijieeb/ijieeb-v2n1/IJIEEB-V2-N1-6.pdf. pp. 37-43
[5] A. Badarudin, C.S. Oon, S. N. Nik-Ghazali, et al. (2013).
“Numerical Simulation and Experiment of Lifting Body with
Leading-Edge Rotating Cylinder.” World Academy of
Science, Engineering and Technology International Journal of
Mechanical, Aerospace, Industrial, Mechatronic and
Manufacturing
Engineering.
(online
article).
http://waset.org/publications/6639/numerical-simulation-andexperiment-of-a-lifting-body-with-leading-edge-rotatingcylinder. Vol. 7, No. 3
COMMERCIAL APPLICATIONS
The most immediate commercial application of lifting body
reentry vehicle technology presents itself to space agencies
conducting research. As it is, spaceflight is a very expensive
field, which is one of the main barriers faced in conducting
space operations. Cost savings in operations costs lends itself
to the possibility of increased frequency of launches that can
be conducted. Increased launches leads to increased
opportunities for research, which in turn may produce results
beneficial to the wider population.
The advantage of increased cross-range of a lifting body
design helps reduce overall logistics costs as a reentry vehicle
has a wider variety of landing sites available to it. This is in
contrast to having to conduct recovery operations for current
blunt-body craft. There are additional cost savings due to ease
of reusability.
The advantages to crew health mentioned previously also
contribute to the commercial attractiveness of lifting body
designs. Safety and comfort of passengers increase positive
perception of spaceflight, which leads to increased public
support and interest. The industry of space tourism is foreseen
to emerge some time in the future, and as such, the qualities of
safety, comfort, and even convenience (by its ability to land at
a wider variety of runways) exhibited by the design are of even
greater importance.
Should the growth of spaceflight continue in a positive
trend, costs will lower, allowing new industries to emerge.
Lifting body reentry vehicles can contribute to the positive
growth of the area of spaceflight, which in turn, helps all
applications of human space travel, present and future.
The technology of lifting body spacecraft is becoming
more widely developed, and functioning examples are
expected to be seen in the coming years.
[6] P. Baiocco. (2007). “Pre-X experimental re-entry lifting
body: Design of flight tests experiments for critical
aerothermal phenomena.” NATO Research and Technology
Organisation.
(Article).
http://ftp.rta.nato.int/public//PubFullText/RTO/EN/RTO-ENAVT-130///EN-AVT-130-11.pdf
[7] “AIAA Code of Ethics.” The American Institute of
Aeronautics and Astronautics (AIAA). (online article).
https://www.aiaa.org/CodeOfEthics/
[8] Meridian International Research
[9] waset.org
[10] Coppinger
[11] esa.int
[12] sncspace.com
ACKNOWLEDGEMENTS
We would like to acknowledge the Writing Center for their
assistance in writing this paper. We would also like to
acknowledge our co-chair Kaitlin Keene for added guidance.
Lastly, we would like to acknowledge the Bevier Engineering
Library for continued support in researching the topic.
REFERENCES
[1] Gibbs
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