Civilian Objectives & Goals Higher, Faster, Longer Distances, - Personal Thrill Cheaper, Safer, Reliable – Passenger Comforts Economical, Easy to Maintain, Spare Part Access, Hanger/Runway Restrictions – Airline Operators Familiar Layout, Less Retraining – Pilots, Crew
Military Objectives & Goals Speed, Maneuverability, Assorted Devastating Payload, Stealth ness Ergonomic and Human Factors associated with Pilot- Blackout, Redout in High g Environment, Oxygen Mask, Ejection Seat etc. Inherently unstable system requiring higher level of flying skill
Civilian- Boeing -777 Passenger 300+ Cargo 150 cu m Fuel 195 kL TO Wt. 340 T Range 16400 km M 0.84, Alt. 10.7 km (LxWxD) 64x65x6.2 m Engine 2 x 50 T 18 hr flight
Military- B-2 Stealth TO Wt. 150 T Payload 18 T Engine 4 x 7.8 T High Subsonic Cruise, 15 km Alt. Range 9600 km (LxWxH) 21x52x5 m Low Operability Multi Role Bomber
Military- Raptor F-22 Air-Dominance Fighter (LxWxH) 19x13.4x4.8 m Mach 2 Sustainable Engines 2 F119 PW- 100 TF Engines with ~ 16 T thrust Projected Date of Operation 2005
Century in Perspective StrengthWeaknessOpportunityThreat I QuarterCuriosity Challenge In-depth Knowledge Mtl./Manuf. Engine Power Military Applications Jealousy II QuarterRace for Supremacy Research Mtl./Limited IC Engine Power /Propeller Military GT Engine Commercial? Suspicion Secrecy III QuarterCommercial Composites Computers Relative War Free Period Cutting Edge Technology Space Race Espionage IV QuarterCustomer Focus IT, Biotech Uni-polar World Globalization Vast Array of a/c Cut Throat Competition
Birds and Bees Bird’s 3 Basic Motion Flapping-Tilting Lift forward for Thrust Twisting TE-Adjust Angle of Attack for Optimum Lift Folding-Wing span Variation for Minimum Drag Unsteady Flow-More Lift + Acceleration Insect with Four Equal Sized Wings Flapping is out of Phase between the Front and the Rear Wings- Foldable underneath when not in use High Amplitude, High Frequency Oscillations
Man v/s Bird – No Comparison Man’s arm has 29 bones It is a complex structure meant for dexterity & can perform skill jobs It has reasonably poor strength Birds arm has only 11 bones which are much longer and are fused together. These are much simpler with fewer joints involving fewer movements & hence rigid. Stronger wings provide Lift + Thrust
Birds Perfectly controlled natural flying machine (8600 species) Feathers: Light strong, flexible Two legs: Hopping & Claws Difficult Landing Adaptive: Body Organs Internalized Bustard: 10kg/1.2 m W Falcon: 160-320 kmph
Wing Shape Feathers give peculiar shape to the wings. The form & function of the same is directly correlated. Birds which fly fast in open air have long narrow wings. These birds experience difficulty during take-off but have long sustaining power. Wing flapping between 60-100 times in an hour depending on calm or rough weather. Woodland birds fly slowly but are extremely maneuverable. These birds have short broad wings with wide feathers.
Marvin Minsky developed the Tentacle Arm, which moved like an octopus. It had twelve joints designed to reach around obstacles. A PDP-6 computer controlled the arm, powered by hydraulic fluids. Mounted on a wall, it could lift the weight of a person.
Large Insects Large Insects Flapping 100~1000/s Flapping: up/down & forward/backward Thorax power sources for wings & legs Skeleton provides weather protection Ultra-light wing structure Static Hovering
Hummingbirds are quite small with a length of only 2 ¼ in to 8 ½ in, however, they are not the smallest of all birds. They eat the nectar of flowers for survival and can consume up to half their weight in sugar daily. The reason for this enormous appetite is the hummingbird’s extraordinary flight capability. The disadvantage of hovering is the excessive energy required for its success. The excessive energy requires the hummingbird to consume a lot of food. The energy output of a hummingbird in hovering flight is ten times as much as a man running nine miles an hour. Direct comparisons to a human being show that a 170-pound man would have to consume about 130 pounds of bread to keep up with a hummingbird’s energy-output University of Texas Project to Study Hummingbird - MAV
Figure "8" motif the wingtips of the hummingbird trace in the air while hovering, as well as the wing patterns at various positions. Notice the change in the pitch attitude of the hummingbird as the speed of the bird changes from top speed to hovering. Basic Equipment used in research: HS Camera, CT Scanner, Frame grabber, MSC/NASTRAN Software, Computer, Photo-Imaging Tools, Aero-elastic Analysis
At the sizes envisioned for these devices, normal aerodynamic rules no longer apply. Micro-flyers will have to operate in an environment more common to small birds and large insects than that of larger aircraft. The forces associated with air moving around the tiny devices are more pronounced than with conventional aircraft in flight, causing increased drag, reduced lift under the smaller wings at low speeds, and decreased propeller efficiency. Such aircraft, weighing only 50 grams, are more susceptible to wind gusts, updrafts, and rain. Other challenges include developing tiny sensors, engines, and power sources for such planes, as well as communications, control and navigation systems for the tiny robot aircraft, which would have to operate with little or no human input. Micro-flyers require an entirely new approach to aircraft design and miniaturization. As flying objects become smaller, the viscosity of the air becomes increasingly important because for the smallest insects, flying is more like swimming through honey. Micro-wings are also susceptible to boundary layer separation. Small changes in the angle of flight can result in extreme loss of lift
Flight Basic Weight: Gravity - Default Thrust: Machine / Muscle Power Lift & Drag: Aerodynamic forces due to Motion Level & Un accelerated Flight: L = W and T = D Flight Control due to unbalanced forces
Human Powered Flight Paul McCready June 79 English Channel Crossing- 22 miles in 2 hrs 49 min (12.5 kmph) 31 m Wing-Span and 31.5 kg weight 50000 UKP Kramer Competition 500 m equilateral triangle clock and anticlockwise in 7 minutes Flt. Speed 10 m/s, Altitude 5 m in a wind speed of 5 m/s at 10 m Alt.
RPV & UAV Tactical Reconnaissance & Surveillance, Missile Simulation 2 Stroke, 4 Cylinder, 24 hp engine + Carbon Propeller or Turbojet (WxLxH) 2.6x3x2.2 m TO 75 kg, Payload 20 kg, CCD Camera Max Speed 320 kmph Cruise 80 kmph Alt. 3km, 50 km Radius Guidance Remote+GPS
RPV & UAV Airborne Experiments Wing 1.75 m Wing Area 0.52 sq m Weight ~ 3 kg Cargo 1.4x3x1.2 cm 200 g fuel, 1.15 L, 1 hp, 2 cycle engine 72 MHz FM Transmitter/ Receiver Video Camera
Autonomous Helicopter Applications Search and Rescue Quick and Systematic Search Lock Position and follow it up
Autonomous Helicopter Applications Surveillance Patrol Area for Unusual Activity Day & Night Operations
Autonomous Helicopter Applications Law Enforcement High Speed Chase Assistance to Police
Autonomous Helicopter Applications Aerial Mapping More Accurate Topological Map Altitude v/s Area of Coverage v/s Resolution
Autonomous Helicopter Applications Cinematography Entertainment
MAV Design Philosophy Robots with High Level of Autonomy Minimum External Resource Dependence Mount System Power, Sensors, Controls, Computers on Board Choice Driven by Weight, Cost, Power Consumption Behavior based Control Approach
MAV Goal Mission Auto Start and Take Off Fly to designated Area on Prescribed Path Avoiding Obstacles Lock on Target and Pursue Send Information, Images back Home Safe Landing All Weather Flying Capability
MAV- Main Characteristics (L / W / H) – Not to Exceed 15 cm Weight 50 g, Payload 20 g Speed 35-75 kmph Cruise Altitude 70 – 100 m Range 10 km Flight Duration 20 – 60 minutes Six Degree Freedom Aerial Robots
Technology Feasibility Micro-ElectroMechanical Systems (MEMS) Integrated Multifunctional System- Sensors, Actuators, Micro-processors Micro-fabrication Techniques Low-Cost Production Potential Fast Processors, Smaller Storage Devices
Innovative Solution Needed Aerodynamics Control Propulsion and Power Navigation Communication Smart Structures
Aerodynamics Reynolds Number = ( u L) / , Limited knowledge at Low Re Low AR- 3-D Effects Agility, Range, Flt. Dyn. Observations for Bird, Insect Limited Mechanizing flight at low Re Difficult Unconventional Wings and Movement
Rotary Wing Low Speed & Hovering Capabilities Possible use in Data Collection on Mars Mission Easily Scalable Useful in studying Wind-Shear
Flapping Wing Imitating Birds Induced Vortex Generation Electric Impulse to Elastomer Actuators causes Contraction and Relaxation Adaptive Wings
Reconnaissance Mission Situation Awareness at platoon Level Real Time Day-Night Imagery MAV Relocating at Vantage Points Unattended surface sensors from Imagery to Seismic Detection
Urban Operation Mission Reconnaissance and Surveillance of Inner City Areas Ability to Navigate Complex Shaped Passages Avoid Obstacles Relay Information back to Manage Urban Disaster / Terrorism
Biochemical Sensing Gradient Sensors and Flight Control Feedback to Map Size of Hazardous Clouds Provide Real Time Tracking Information
MAV Applications Packed with Ejector Seat Mechanism of Aircraft-Sends Signals about Downed Pilot MAV could be used for Traffic Monitoring, Border Surveillance, Fire and Rescue Operations, Forestry, Wild-Life Survey, Power Line Inspection, Aerial Photography MAV can Provide targeting Information & Battle Damage Assessment Barrel or Overhead Flight Vehicle Launch is Possible
MAV System Integration MEMS based Components Individual Components Occupy More Space On-board Processor & Communication Electronics- MAV Core Critical Link between Major Subsystems is Important Multifunctional use & Synergy is Crucial
Propulsion Low Re -> L/D~1/3-1/4 -> Need More Power Small Propellers have Poor Efficiency Realized Power is Less Higher Energy Density is Necessary Battery Technology -> Fuel Cell Use
MAV Control Guidance Communication Current GPS is Too Heavy and Power Intensive Human Responses for Enhanced Agility are Slow Miniaturized and Advanced Navigation, Guidance and Control need to be Developed
MAV Payload Sensors-Optical,, IR, Acoustic, Bio-chemical, Nuclear Visible Imaging System-1 cu cm Camera Weighing 1 g with 1000x1000 pixels and requiring 0.25 milliwatt power Mature Technology is Available
MIT Concept of MAV 8 cm vehicle with 10 g weight & total power requirement of 1 watt Propulsion needs 90% of Total Power and takes 70% of Total Weight Forward mounted Video System looking down at 45 degree at 2 frames/s
Smart Structure: Entomopter Mechanical Insect Reciprocating Chemical Muscle (RCM) Generating autonomic wing beating from a chemical energy source Adaptive Wing Concept Self Repairing Structures & Nano- Technology Through direct conversion, RCM provides small amounts of electricity for onboard systems Robert Michelson, Georgia Tech Research Institute
Weight Issues Small Size -> High Surface to Volume Ratio Constraints on Weight and Volume Develop and Integrate Physical Elements & Components Multifunctional amongst System Components
Presently, work is progressing to develop the wings for the Mars Entomopter. Stereo-lithography and Fused Deposition Modeling techniques have allowed Michelson's design team to create intricate wing structures directly from computer models. Careful attention is being paid to material selection. Resilience, stiffness in opposite planes, chemical compatibility, and ease of bonding are but a few of the points to be considered in choosing wing materials. Wings have been grown in our stereo-lithography machines as well as ABS wing stiffening structures produced using Fused Deposition Modeling (FDM) methods with, and without interstitial materials. The interstitial material has been placed over the flexible wing structure to demonstrate that micro-channel ribs can be produced to create a wing that can distribute gas to portions of the wing for active flow control to increase lift and produce attitude control moments. Later wing designs are greatly simplified with a single "spar channel" encased in a composite thin wing.
Researchers from the Departments of Aerospace & Mechanical Engineering and Electrical & Computer Engineering at the University of Florida are doing on-going work on vision-guided autonomous flight for Micro Air Vehicles (MAVs).
Indian Efforts Indians involved in Research in MAV in USA (MIT, Georgia etc.) NAL, IISc, IITs carrying out Elementary Experimental and Simulation Work Commitment from Raksha Mantralaya as a Priority Area Lot more needs to be done Rudimentary MEMS Work Undertaken in a Few places
Flow past two impulsively started cylinders at Re=550 (15 seconds). Ph.D. Work of Prabhu Ramachandran, Dept. of ASE, IIT-Madras. IIT-M Efforts: CFD Simulation
5 degrees 10 degrees 15 degrees Flow Past Flat Plate at an Angle of Attack (Re=1000). Simulation time 10s. Ph.D. Work of Prabhu Ramachandran, Dept. of ASE, IIT-Madras
Flow past an oscillating flat plate. Work done at Cal. Tech.
Concept - Using thermoelectric generator modules to convert engine waste heat energy to useful electric energy for micro air vehicles Result - An enabling technology for extending the endurance and mission capabilities of micro air vehicles. Fleming, J. L., Ng, W. F., and Ghamaty, S., "Thermoelectric-Based Power System for UAV/MAV Applications", AIAA Paper 2002-3412, Unmanned Aerospace Vehicles, Systems, Technologies, and Operations Conference and Workshop, Portsmouth, VA, May 20-23, 2002.