APPLICATION OF NATURAL LAMINAR FLOW T O A SUPERSONIC TRANSPORT CONCEPT Henri D. Fuhrmann* NASA Langley Research Cent er Hampton, Virginia 23681-0001 Abstract Results are presented of a prelimina ry investigation into an application o f supersonic natural laminar flow (NLF) technology for a high speed civil transport (HSCT) configuration. This stu dy focuses on natu ral laminar flow without regard to suction devices which are required for laminar flow control (LFC) or hybrid laminar flow control (HLF C). An H SC T design is presented with a 70 ' inboard leading-edge sweep and a 20" leading-edge outboard crank to obtain NLF over the outboard crank section. This configuration takes adva ntage o f improve d subsonic performanc e and NLF on the low-sweep portion of the wing while minimiz ing the wave drag and induced dra g penalt ies associated with low-sweep supersonic cruise aircraft. In order to assess the benefits o f increasing natural laminar flow wetted area, the outboard low-sweep wing area is parametrically increased. Using a range o f supersonic natural laminar flow transition Reynolds numbers, these aircraft are then optimized and sized for minimum take-off gross weight (TOGW) subject to mission constraints. Results from this stud y indicate reductions in TOGW for the NLF concepts, du e mainly to reductions in wing area and total wing weight. Furthermore, significant reductions in block fuel are calculated througho ut the range o f trans ition Reynolds numbers considered. Observations are made on the benefits o f unsweeping t he wingtips with all turbule nt flow. Nomenclature A2IA~ Ratio o f th e outboar d wi ng area to total theoretical wing area CD Drag coefficient C D~ Nacelle base drag coeffi ci ent CDW Wav e dr ag coefficient FLOPS Flight optimizati on syste m FN/WGTO Take-off thrust-to-weight ratio - *~eros~ace ngineer, member AIAA HLFC HSCT LF C L/D M NLF n.m. R t r sw T B E TOFL Hybrid laminar flow control High speed civi l transport Laminar flow control Lift-to-d rag ra tio Free-stream Mac h numbe r Natural laminar flow Nautical miles Transitio n Reynolds numbe r Wing reference area Turbine bypass engine Tak e-o ff field leng th TOG W Take- off gross weight TOGW/TOGWA Take -o ff gro ss weight normalize d to that o f reference arrow-wing Ww/WWA Wing weight normalized to t hat of reference arrow-wing Introduction The National Aeronautics and Space Administration (NASA) has recently begun to focus on high-speed research with the intent o f pro viding the techn ology for an economically viable commercial supersonic transport to be certified aroun d the year 20 05 .' By the year 2015, more than 600,000 passengers a day are expected to be flying on the long, over-water routes that a supersonic transport could economically serve.2 The United States must act decisively to capture this lucrative market and bolster the positive balance of trade generated by the aerospace industry. In order to help U.S. companies produce an aircraft that will be both economically viable and environmentally compatible, NASA must consider and examine all promisin g technologies and the advantages they may offer for supersonic flig ht. Supersoni c transport wing concepts have evolved into highly effici ent cranked wi ng planform designs. These planforms consist o f an inboard section with a subsonic leading edge swept behind the local Mach angle, and an outer panel of reduced sweep to enhance low-speed stabili ty and performance. The highly swept inboard section achieves high aerodynamic effic ienc y at cruise because o f its subson ic leading edge Copyri ht O 1993 y the American Institute of Aeronautics and Astronautics Inc. No mp yr ia t is asserted in the United States under Title 17 U.S. Code. The U.S. Government has a royak free license to ex8rc is.e all rights under the'copyright claimed herein for ~ov ern me nri l urposes. All other r~ghts re reserved by the wpyr~g ht wner.
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Application of Natural Laminar Flow to a Supersonic Transport Concept (AIAA-1993-3467-139)
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7/31/2019 Application of Natural Laminar Flow to a Supersonic Transport Concept (AIAA-1993-3467-139)
numbers, these aircraft are then optimized and sized
for minimum take-off gross weight (TOGW) subject to
mission constraints. Results from this study indicate
reductions in TOGW for the NLF concepts, due mainlyto reductions in wing area and total wing weight.
Furthermore, significant reductions in block fuel are
calculated throughout the range of transition Reynolds
numbers considered. Observations are made on the
benefits of unsweeping the wingtips with all turbulent
flow.
Nomenclature
A 2 I A ~ Ratio of the outboard wing area to
total theoretical wing area
CL Lift coefficient
CD Drag coefficientC D ~ Nacelle base drag coefficient
CDW Wave drag coefficientFLOPS Flight optimization system
FN/WGTO Take-off thrust-to-weight ratio
-* ~ e r o s ~ a c engineer, member AIAA
HLFC
HSCT
LFC
L/DM
NLF
n.m.
Rtr
swTBE
TOFL
Hybrid laminar flow control
High speed civil transport
Laminar flow control
Lift-to-drag ratio
Free-stream Mach number
Natural laminar flow
Nautical miles
Transition Reynolds number
Wing reference area
Turbine bypass engine
Take-off field lengthTOGW Take-off gross weight
TOGW/TOGWA Take-off gross weight normalized
to that of reference arrow-wing
Ww/WWA Wing weight normalized to that of
reference arrow-wing
Introduction
The National Aeronautics and Space Administration
(NASA) has recently begun to focus on high-speed
research with the intent of providing the technology
for an economically viable commercial supersonictransport to be certified around the year 2005.' By the
year 2015, more than 600,000 passengers a day are
expected to be flying on the long, over-water routes
that a supersonic transport could economically serve.2
The United States must act decisively to capture this
lucrative market and bolster the positive balance of
trade generated by the aerospace industry. In order to
help U.S. companies produce an aircraft that will be
both economically viable and environmentally
compatible, NASA must consider and examine all
promising technologies and the advantages they may
offer for supersonic flight.
Supersonic transport wing concepts have evolved into
highly efficient cranked wing planform designs. These
planforms consist of an inboard section with a
subsonic leading edge swept behind the local Mach
angle, and an outer panel of reduced sweep to enhance
low-speed stability and performance. The highly
swept inboard section achieves high aerodynamic
efficiency at cruise because of its subsonic leading edgeCopyri htO 1993 y the American Institute of Aeronautics and Astronautics Inc. Nomp yr ia t is asserted in the United States under Title 17 U.S. Code. The U.S. Governmenthas a royak free license to ex8rcis.e all rights under the'copyright claimed herein for~ov ern me nri l urposes. All other r~ghts re reserved by the wpyr~g ht wner.
7/31/2019 Application of Natural Laminar Flow to a Supersonic Transport Concept (AIAA-1993-3467-139)
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7/31/2019 Application of Natural Laminar Flow to a Supersonic Transport Concept (AIAA-1993-3467-139)