Expanding the range of possibilities-Biomimetics Airplane Design: Past, Present and Future – An Early 21st Century Perspective Affiliate Professor Department of Aeronautics and Astronautics University of Washington Seattle, WA John H. McMasters Technical Fellow The Boeing Company email@example.com and April 2007 Ed Wells Partnership Short Course Based on: American Institute of Aeronautics and Astronautics (AIAA) & Sigma Xi Distinguished Lectures & Von Kármán Institute for Fluid Dynamics Lecture Series: “Innovative Configurations for Future Civil Transports”, Brussels, Belgium June 6-10, 2005
A Area (ft.2, m2) a Speed of sound (ft./sec., m/s) AR Aspect ratio, b/č = b2/S b Wing span (ft., m) č Average wing chord (ft.,m) CF Force coefficients (lift, drag, etc.) = F/qS Cℓ Section (2D) lift coefficient CM Moment coefficient = M/qSĉ Cp Pressure coefficient = Δp/q D Drag force (lb., N) E Energy (Ft.-lbs., N-m) e “Oswald efficency factor” ew Wing span efficiency factor (= 1/kw ) F Force (lift, drag, etc.) (lbs., N) H Total head (reservoir pressure) I Moment of inertia kw Wing span efficiency factor (= 1/ew) L Lift force (lb., N) ℓ Length (ft., m) M Mach number (V/a) M Mass (kg) M Moment (ft. lbs., N m) P Power (ft.-lbs./sec., N-m/sec.) p Static pressure (lbs./ft.2) q Dynamic pressure (lbs./ft.2) = ½ρV2 R Range (mi., km) Rn Reynolds number (ρVℓ / μ) S Wing area (ft.2, m2) T Thrust (lb., N) T Temperature (oF) u Local x-direction velocity component V Velocity, Speed (ft./sec., m/s, mph, km/h) v Local y-direction velocity component w Downwash velocity (ft./sec., m/s) ż Sink rate (vertical velocity) (ft./sec., m/s) Greek: α Angle of attack (deg.) Γ Circulation γ Climb or glide angle (deg., rad.) γ Ratio of specific heats in a fluid ε Wing twist angle (deg.) θ Downwash angle (deg.) φ Velocity potential Λ Wing sweep angle (deg.) μ Dynamic viscosity ν Kinematic viscosity (μ/ρ) ρ Fluid mass density (kg/m3) Notation and Symbols Used
Presentation Overview • Expanding the range of possibilities • (Biomechanics of flight and morphing aircraft)
A Cosmic View of Aviation History Neil goes to the Moon Mass extinction from space Future of The World Economy ? X Insects Dinosaurs Birds ?? Life Evolves On Earth Boeing ManWright Bros. Solar System Formed Global climate change Big Bang Future of Earth ? ~ 300 million years of flight
To address societal needs and sustain an industry that continues to contribute to our national and global economy: Build an effective, efficient, safe and environmentally acceptable global air transportation system Contribute to our national security in the face of an increasing number of non-traditional threats Provide an important component to the “affordable access to space” 21st Century Challenges for Aeronautics
A Developing World-Wide “Perfect Storm” ?(Some Global Challenges for the 21st Century) Increasing World Population “I’m sure glad the hole isn’t in our end…” Global Climate Change Cultures/Institutions Unable or Unwilling To Change We, as a global community, are all in this together. Finite Supply of Key Natural Resources (Oil, Water, Minerals) Engineers play a fundamental role in any solutions or ameliorations!
The Nine Dot ProblemThe Origin of “Out of the Box” Thinking(or a Paradigm for Paradigm Shifting) Problem: What is the MINIMUM number of straight lines required to connect the nine dots shown without lifting the pencil from the paper?
Solving the Nine Dot Problem Basic Solution: 5 lines [Government required solution: 6 lines (5 lines to solve the problem and one more to assure compliance)]
Solving the Nine Dot Problem (2) The Creative Rocket Scientist’s Solution: 4 lines
Solving the Nine Dot Problem – The Final Frontier An 8-year Old Student’s Solution: Transform the nine dot problem into a “one dot” problem and jam a pencil through it (i.e. one line) Yes, it this is an “exact solution”; one line 9 thickness’ of paper in length. Fold Fold Thanks to Dr. Paul B. MacCready Jr.
Opportunities in the Knowledge Domain A balanced approach is needed. Aware “What we know we know.” “What we know we don’t know.” Knowledge Re-use Targeted Research Potential big $$$$ savings Unknown Known Curiosity-based Research “Prospecting” Hunting & Searching Traps & Surprises [Competitive Risk] “What someone knows, but that we haven’t found yet.” “What we don’t know we don’t know.” DARPA land Unaware
A More Complete View of Aviation History Insects Birds Proto-reptile Mammals Bats Pterosaurs Extinct Anemophilous Seeds Paleozoic Era Mesozoic Era Cenozoic Era • 248 65 Million Years Ago
Opportunities for Expanding the Range of Aeronautical Inquiry Extremes in Variable Geometry Wings Formation Flight Solar Powered Flight Unsteady Aerodynamics Ultra-Quiet Flight Micro Air Vehicles (µAVs)
Joel Grasmeyer’s “Microbat 3”Micro Air Vehicle Attacked by a Seagull A penny for size comparison
Insects and Entomological Engineering McMasters, J. H., “ The Flight of the Bumblebee and Related Myths of Entomological Engineering”, Amer. Scientist, Vol. 77, March- April, 1989, pp. 164-69. See Michael Dickinson’s work at Cal Tech at: http://www.dickinson.caltech.edu
The Myth of the Bumblebee– The Aerodynamicist’s Bane Aerodynamicist Proves Bumblebees Can’t Fly! The tabloids do it to science again? Seattle Muckraker Guru remains in trance for 20 years ..without food or drink $1..00 September 10 Elvis is Alive, Living in Argentina A 380 News Flash…. Britney Spears to run for governor of New York Giant fly devours jumbo jet …. Hundreds missing Astrophysicists find dark matter …its cosmic cow poop
The Myth of the Bumblebee – The Aerodynamicist’s Bane The Actual Origin of the Bumblebee Myth From A. Magnan, Le Vol Des Insects, Paris: Herman and Cle, 1934 (p. 8): “Tout d’abord, pouss’e par ce qui fait en aviation, j’ai applique’ aux insectes les lois de la resistance del’air, et je suis arrive’ avecM. [Andre] SAINTE-LAGUEa cette conclusion que leur vol est impossible.”
Typical Variation in Aerodynamic Efficiency (Lift-to-Drag Ratio) with Reynolds Number Size Matters ! Std. Aero. E. textbooks “Smooth” Model (Variable Boundary Layer Transition Locations) Large-Scale Laminar Flow Separation on “Smooth” Models 20 10 Maximum Subsonic Lift-to-Drag Ratio “Rough” Model (Fully Turbulent Boundary Layer) “Insect-like” Wings Bacteria flagella Bumblebee Sailplanes Birds 0 Insects Wind Tunnel Testing Large Airplane Flight 103 104 105 106 107 108 Reynolds Number (based on average wing chord) 10-5
Drag Variation With Reynolds Number Flat plate CD = 2.0 (height = d) Cylinder CD = 1.2 (diameter = d) Streamlined Body CD = 0.12 (thickness = d) Cylinder CD = 1.2 (diameter = 0.1d) Cylinder CD = 0.6 (diameter = d) Rn = 105 Rn = 15,000 Rn = 105 Curve for a circular cylinder Drag coefficient (CD) – based on frontal area Rn = 105 Rn = 104 With dimpling Rn = 107 Reynolds Number (Rn) While laminar flow produce lower drag, a turbulent flow is much more resistant to separation.
Aerodynamic Performance of a Crane Fly Airfoil Airfoil A Section Lift Section Lift Tipula oleracea Airfoil B Airfoil B a b c d e Angle of Attack Section Drag a b c d e A B a-a b-b c-c d-d e-e Tests in glycerin @ Rn = 900 Rees, C.J.C., “Aerodynamic properties of an insect wing section and smooth airfoil compared”, Nature, Vol. 258, 1975, pp.141-42.
Dragonfly Flight Testing and Flow Visualization http://jeb.biologists.org/cgi/content/full/207/24/4299
Flow Visualization on a Model Insect Wing Oscillating in Pitch http://jeb.biologists.org/cgi/content/full/207/24/4299
Witold Kasper and Trapped Vortices(“Enhanced Circulation” Wings) Vortex Flaps extended Lift - L Vortex Flaps retracted SAAB wing with span-wise jet Kasper “Bekas” sailplane Angle of Attack - α The Kasper wing does produce the vortices shown, but they have been proven to be unstable unless some method is employed to keep them intact (e.g. the SAAB scheme above). As flown, this was an extremely dangerous airplane. [Kruppa, E.W., “A wind tunnel investigation of the Kasper vortex concept”, AIAA 1977-310, Wash. DC, Jan 10-13, 1977.]
Wakes From Flapping Wings De Laurier Ornithopter (2006) Wake behind a cruising butterfly (Kokshaysky, N.V. “Tracing the wake of a flying bird”, Nature, Vol. 279, 1979, pp. 146-8.)
Various Ways to Create Wings From the Same Basic Set of Bones in Vertebrates Very limited span and area change capability, but as living tissue, the membrane is part of a sophisticated “smart wing” system Great ability to change span, area, sweep, twist and dihedral – symmetrically and asymmetrically. Pterosaur 1 2 3 4 Bird Human Bat Limited ability to change span and area, but powerful ability to control camber and twist.
The Wonders of Bird Flight Thanks to Sharon Finn
A California Condor (Gymnogyps californianus) in a Glide • Important Aeronautical Technology Incorporated • In Birds • Mission Adaptive Wing • Active Controls/ Control • Configured Vehicles • Composite structures • Damage Tolerant • Structures • Fully integrated System • Design • Advanced • Manufacturing • Techniques
One Possibility for the Origins of Bird Flight A plausible (and probably testable) explanation for a cursorial origin for the evolution of flight in birds due to Phillip Burgers and Luis Chiappe. Ref. Burgers, P. and Chiappe, L.M., “The wing of Archaeopteryx as a primary thrust generator”, Nature, Vol. 399, 6 May 1999, pp. 60-2.
Tandem Wing Fliers Microraptor gui Northern China 125 Mya Rutan “Proteus” (circa the present) www.scaled.com 77 cm (~ 30 in.) V Ref. Xu, et al., Nature, Vol.421, 23 January 2003, pp. 335-40. A feathered analog to a flying squirrel?
The Possible Origin of Birds Within theTheropod Dinosaurs (after Prum, 2003) Microraptor gui (~ 125 mya) Archaeopteryx lithographica (~ 140 mya) Evolution of powered flight, and loss of hind wings Evolution of four feathered wings and gliding Feathers ? I personally doubt this (except for the case of insect evolution). Richard O. Prum, Nature, Vol.421, 23 Jan. 2003, pp. 323-4
Case Study: The Quiet Flight of OwlsWonders of Owl Wings and Feathers Owls are: • Highly evolved and specially adapted primarily as nocturnal predators, often flying in confined spaces Need to fly slowly and with a high degree of maneuverability • Splendid examples of natural “stealth” technology Approach not detectable by prey while using highly developed bi-aural direction finding and night vision Note: The owl’s adaptations to do these two things are often confused with each other. They turn out to be synergistic. With thanks to Geoffrey M. Lilley and James Snyder
Basic Physics of Owl – Prey Interaction Lift (L) ~ V2 Drag (D) ~ V2 Speed (V) Distance - r Weight (W) Noise varies as ~ V5 / r2 Aerodynamic forces vary as ~ V2 Prey
Owl Wings and Feathers Have Special (and Sometimes Unique) Adaptations • To fly slowly (and thus with low noise) and maneuverable • A wing of relatively large area for its body weight • Special comb-like structures on the leading edges of the leading primaries that generate vortices that increase lift • To reduce noise audible to their prey (and not interfere with their own hearing - ”direction finding”) • Feathers with a velvety surface texture reduce mechanical rubbing and rattle, and “kill” higher frequency air flow noise • A soft and serrated wing trailing edge that diffuses and damps higher frequency components of air flow noise
Owl Feather Adaptations Combs on Leading Primaries Specialized form of vortex generators for increased lift for slow flight and enhanced maneuverability Velvety feather Surfaces Reduces both mechanical and aerodynamic noise Soft, Serrated Wing Trailing Edge Diffuses and reduces higher frequency edge noise
Owl Wings and Feathers Have Special (and Sometimes Unique) Adaptations The “Silent” Flight of Owls: Owl hearing range 100Hz - 20 kHz Lower limit of prey hearing range Owl bi-aural hearing range 3 - 6 kHz Typical spectrum of sound generated by most birds[qualitative only] Sound Intensity SPL- sound pressure level Owl noise spectrum Mouse squeaks and leaf rattles 2 10 Sound Frequency kHz
Some Conclusions About Owls • Owls don’t really fly “noiselessly”, they merely manage the noise they generate in relation to the hearing ability of their prey • Owls are highly and very cleverly adapted for what they do (and where and when they do it) • Several features of owl feathers are unique among birds (leading edge combs, velvety feathers, soft wing trailing edges) • Not all owls have all these adaptations (e.g. fishing owls lack leading edge combs) • Experiments in which the leading edge wing combs and trailing edge fringe were clipped from the wing showed a large deterioration in an owls ability to fly - and noise generated more like that of other birds.
Pterosaurs – 150 Million Year of Success(A Natural Model of Cylindrically Cambered Rogallo Wings) Rhamphorhychoidae Older “stability configured” sub-order. Rhamphorhynchus sp. Newer “control configured” sub-order (no tails). Pterodactyloidea Note: Although they share a common ancestor, pterosaurs are not dinosaurs. They existed contemporaneously and also became extinct at the end of the Cretaceous, 65 million years ago. Pteranodon ingens (Wing span ~ 7 m)
Rogallo Wings & Hang Gliders “Batso” circa 1971
The Relative Aerodynamic Efficiency of Conically and Cylindrically Cambered Rogallo Wings “High” AR cylindrically cambered Lift-to-Drag Ratio L/D Lift coefficient - CL
How Pterosaurs Really Worked Remains Controversial Pteranodon ingens Adult wing span ~ 7 m After R. McN. Alexander More recent “Narrow Wing” Conjecture Traditional “Broad Wing” Model After Bramwell and Whitfield38 After Padian, circa 1985 Awkward quadruped ? Bipedal runner ?
The Texas Pterosaur ( Quetzalcoatlus northropi ) Max. adult wing span ~ 12 m (~ 39 ft.) California Condor Possible “narrow wing” membrane ? Possible “broad wing” membrane ? Conjectural uropatigium
Gravity According to Newton(The Shrinking Earth Hypothesis)For which there is currently no shred of evidence - yet. Assume the Earth has been shrinking as it cools since it first formed….. F = k M m R2 m Where: F = mutual force of attraction (or weight of object of mass m) M = mass of the earth R = distance between the centers of the two masses K = universal gravitational constant m RtRn Fn Ft M Thus: If, say 100 my bp, Rt was 20% larger than now (Rt = 1.2 Rn), and M and m are constant over time, the same object (m) on or near the surface of the Earth would have weighed 31% less then than it does now (Ft = 0.69 Fn). This example represents an average, almost undetectable change in diameter of less than three meters per century !
The MacCready Robotic Replica of the Texas Pterosaur Quetzalcoatlus northropi (circa 1986) From the Texas Cretaceous circa 70M years ago. Adult wingspan up to ~ 40 ft.
Pterosaur Brains Pterosaur Brains 5 4 3 2 1 0 Birds Pterodactyloids Anhanguera Log Brain Mass (mg) Non-avian reptiles Rhamphorhynchus Note: The floccular lobe in pterosaur brains has been found via CAT scans of fossil skulls to be greatly enlarged relative to that in other animals. The purpose of the flocculus is to collect and organize sensory data received from the network of nerves distributed through the animal’s body (including the living tissue in the wing membrane). 0 1 2 3 4 5 6 7 log Body Mass (g) Anhanguera piscator Rhamphorhynchus
Size MattersThe Square-Cube Law Applied to “Geometrically Similar” Animals L = characteristic length L2 ~ area (surfaces and cross sections) L3 ~ volume (and thus weights) Consider a spherical cow: L A B C How big ? Z Y X How small ?
Mass - Wing Area Relations for Flying Devices in Comparison with the Square-Cube Law 103 10 -3 Wing Area S (m2) M = S3/2 1 M = 15 S3/2 10 -3 10 –6 1 106 Mass – M (kg)
Comparison of Large Soaring Birds Different Soaring Modes and Environments Different Geometries Wandering Albatross (Diomedae exulans) California Condor (Gymnogyps californianus) Albatross Condor Wing Span (m) 3.5 3.0 Wing Area (m2) 0.72 1.5 Aspect Ratio 17 6 Mass (kg) 9.8 10 Wing Loading (kg/m2) 13.6 6.6