Capability-Based Electric Personal Air Vehicles May 23rd 2007 Electric Aircraft Symposium Mark D. Moore NASA Langley Research Center 757.864.2262 [email protected] Prior Research Capabilities Missions The 100/100 Aircraft Enabling Technologies Prior Research • Not What Industry Considers All Electric – The Prospects and Potential of All Electric Aircraft, Cronin, LockheedCalifornia, AIAA-83-2478, 1983. – Evaluation of All-Electric Secondary Power for Transport Aircraft, McDonnell Douglas, MDC Report 91K0418, 1992. • Really Good Primer for Electric Vehicle Issues – Vehicular Electric Power Systems – Land, Sea, Air and Space Vehicles, Emadi, Illinois Institute of Tech, Marcel Dekker, 2004. • One of the Best Overall Electric Aircraft Technology Reports – Electric Power System for High Altitude UAV Technology Survey, Schmidtz, Paul, NASA Ames, 1997. Prior Research • Fuel Cell Electric – Investigation of Fuel Cell Power System for Aircraft Electric Propulsion, Stedman, J.K., Naval Air Warfare Center FCR-12194A, 1992. – Fuel Cell Powered Electric Propulsion for HALE Aircraft, Bentz, John, Naval Air Development Center, American Society of Mechanical Engineers Paper 92-GT-404, 1992. – Fuel Cell Propulsion for All Electric PAV, Kohout, Lisa, NASA TM 2003212354, 2003. – Fuel Cell Aircraft Applications Presentation, Dunn, Jim, Portable Fuel Cell Conference, 2002. – Latest GM Fuel Cell Developments, Bosco, Andrew, GM, 2001. – Hydrogenics Fuel Cell Specifications. Prior Research • Electric UAVs – Flight Testing of an Electric Powered Vehicle, Cross, US Naval Research Laboratory, AIAA Paper 92-4077, 1992 – Performance Characterization of a Lithium-Ion Gel Polymer Battery Power Supply System for an Unmanned Aerial Vehicle, Reid, Concha, NASA Glenn Research Center, SAE 2004-01-3166. – Flight Testing of an Electric Powered Vehicle, Cross, US Naval Research Laboratory, AIAA Paper 92-4077, 1992 • Recent Articles and Activities – Electric Flight – A Design Exploration, Palmer, EAA Sport Aviation, March 2007. – Electric Airplane (E-Plane), Stough, Paul, NASA Langley, Jan 2007. – Air Travel Greener By Design, Report of the Technology Sub-group, 2001. Prior Research • Small Aircraft Design Studies with Electric Propulsion – Electric Propulsion for High Performance Light Aircraft, Galbraith, A.D., Continental Group, AIAA 79-1265, 1979. – Practical Feasibility Assessment of Electric Power Propulsion in Small Helicopters using Lithium Hydroxide Battery Technology, Kirchen, Hughes Helicopters, 1981. – An Analytical Performance Assessment of a Fuel-Cell Powered Small Electric Airplane, Berton, NASA TM-2003-212393, 2003. – Emissionless Aircraft: Requirements and Challenges, Arun, Partial Unpublished Paper, 2003. Prior Research • Electric Sailplanes – Silent Worldwide Debut, SSA Convention and Airsports Expo, 2003. – Silent The Light Sailplane with a Glide Ratio Greater than 31, Alisport. – Silent AE-1 Specifications. – Silent IN Specifications. – Silent US Price List, 2003. – Antares A Self-Starting Silent Super Sailplane, Boermans, L.M.M., Soaring Magazine, Feb 2001. – Antares Electric Motorglider, Lange Flugzeugbau, 2005. – Antares The Electric Motorglider from Lange Flugzeugbau Part 1,2001. – Antares Fully Equipt – Sparrowhawk Ultralight Sailplane, Greenwell, Eric, Soaring Magazine, Jan 2001. – Battery Powered Sailplanes, Gehrmann, OSTIV Congress, 1999. Prior Research • Hydrogen Vehicles – BMW Hydrogen Vehicle Presentation, Gebler, 2002 Clean Energy Seminar. – Hydrogen – The Fuel for Future Powertrain Technologies, Braess, BMW Motor Group, 2002. – Hydrogen Storage, Niedzwiecki, Alan, Quantum Technologies, Hydrogen Vision Meeting, 2001. Prior Research • On the Wild Side – Futures of Civilian Aeronautics Presentation, Bushnell, Dennis, 2007. – Advanced Energetics for Aeronautical Applications, Alexander, MSE Technology Applications, NASA CR-212169, 2003. – Tip Driven Fan Based on SERAPHIM Technology, Marder, Barry, Sandia National Lab, SAND2002-0029, 2002. – Electromagnetic Thrust Patent, Campbell, Patent 6,317,310, 2001. – Electromagnetic Thrust Patent, Patrick, Patent 6,362,718, 2002. – Why Small Engines, Edkins, General Electric, SAE, CN-51880, 1957. Prior Research • Web Pages – Batteries • Lithium Polymer (SAFT, Electrovaya, Apogee, Maintence) • Lithium Ion (Toshiba, Panasonic, Prismatic Polymer, Cells for Military Applications) • Lead Acid (TMF) • Carbon (Isuzu FDK) • NiMH (Ovonic) • Zinc/Air (LBL) – Fuel Cells – SoLong Solar Electric AC Propulsion UAV – Solar Cells (Beco Solar, Uni-Solar, United, Full Spectrum) – Ultra Capacitors (Power Cache) – Electric Motors (UQM) Capabilities • Major concern in approaching electric propulsion technologies for aircraft is to insure desired capabilities determine approaches, not a pet technology area. – What is the justification for investment over alternative approaches? – Electric propulsion promotes low emissions, noise, and improved safety, ease of use, and reliability as desired capabilities, but require a dramatic increase in cost while decreasing efficiency (for a conventional installation). – Why should stakeholders invest in this technology for aircraft? • Private investors • Small aerospace (AeroVironment, Scaled Composites, Cirrus) • Mid-size aerospace (Cessna, Raytheon) • Large aerospace (Boeing, Lockheed, Northrup) • Government (NASA, DARPA, FAA) • Non aerospace (Toyota, Honda, GM) Personal Air Vehicle GOTChA GOALS Reduce Training Time/Cost Goal = 5 days $1000 SOA = 45 day $10,000 1 Reduce Avionics Cost Goal = $15K/ suite SOA = $100K/ suite 2 Reduce Airframe Cost Goal = $20/ lbm struc. SOA = $100/ lbm struc. 3 Reduce Propulsion Cost Goal = $10/ lbf SLS thrust SOA = $40/ lbf SLS thrust 4 Reduce SFC Cruise Goal = .22 lbm/lbf hr SOA = .28 lbm/lbf hr 5 Reduce Community Noise Goal = 60 dBA @ TO/Land SOA = 84 dbA @ TO/Land 6 OBJECTIVES Reduce flight training time and cost by 90%. 01 Decrease avionics suite cost by 85%. Reduce airframe cost by 80%. 03 02 Reduce cruise sfc by 20%. Decrease propulsion system cost by 75%. 04 05 Reduce community noise by 24 db at flyover TO/landing. 06 TECHNICAL CHALLENGES Developing, integrating, flight architecture and control systems that are failsafe and reliable. 01 Developing and certifying flight architecture and control systems within cost. 02 Developing and certifying low labor assembly time structures at modest production volumes. Quality Assurance (QA) based certification procedures instead of Quality Control. 04 Develop reduced part count and lean design structural design concepts. Adapt mass produced QA products for aviation use.while developing new certification procedure framework. 03 APPROACHES Develop Naturalistic Flight Control Deck with control, guidance, sensing, avoidance, and airborne internet. 01 Develop health monitoring, healing, and recovery for failsafe user interfaces and flight critical systems.. 02 Develop autonomous operation capability within Digital Airspace 03 Develop streamlined software and systems certification procedures, processes, and tools 06 04 Develop certifiable simulatorbased training that facilitates use of Naturalistic Flight Deck. 05 Advanced low cost fastener technologies ie adhesives, laser and friction stir welding. 09 07 Validate low cost mfg processes, materials, and techniques for major components. Achieving low cost variable pitch ducted prop while maintaining efficiency in acoustically constrained system 05 Develop lowcost variable pitch ducted propeller hub and blades for low tipspeed,. 10 Reducing community and cabin propulsion noise sources (ie high tipspeed prop, asymmetric flow, exhaust, etc) while meeting performance reliability, and cost. 06 Develop integrated and shielded ducted propeller system with active wake control, and acoustical suppression. Develop engine exhaust systems that can survive sustained high power operation. 12 11 08 - Page 1 12 SOA = Cirrus SR-22/TCM IO-550N Personal Air Vehicle GOTChA GOALS Increase L/D Cruise Goal = 16 Decrease Empty Wt Fraction Goal = .58 Increase Propulsion System T/W Goal = 4.0 Increase Clmax Landing Goal = 9.0 Reduce / Eliminate Harmful Exhaust Emissions Goal = 0 SOA =11 SOA = .65 SOA = 2.0 SOA = 2.2 SOA = 350 CO2, 80 CO, 10 HC, 3.5 NOx, .2 lead (grams/mile) 11 8 7 10 9 OBJECTIVES Increase Clmax and L/D by 50% with a cruise-sized wing. 07 Reduce structural weight fraction by 15% Increase propulsion system T/W by 100%. Reduce subsystem weight fraction by 20% 08 09 Reduce required field length by 75%. Reduce HC, CO, CO2, particulates, and lead emissions by 100% 12 11 10 Reduce NOx emissions by 100% 13 TECHNICAL CHALLENGES APPROACHES Achieving simple, effective, highlift system for higher wing loading for efficiency and ride quality at low cost and high reliability. Lightweight minimum gage structures that achieve low cost.and assembly. 08 Lightweight subsystems that achieve low cost and high reliability. 09 Achieving high power to weight propulsion system while maintaining equivalent cost and maintenance. 10 13 Combustion based processes produce harmful emissions as a byproduct. 12 Current noncombustion based power generation, distribution, propulsion, and energy storage systems have low specific power and energy density. 13 11 07 Develop no external moving part Circulation Control highlift system (coanda blowing over trailing edge). Achieve simple, effective, powered-lift highlift system with low speed gust control and engineout robustnes at low cost. Lightweight, low density, stiff materials for minimum gage structures. 14 Integrated multipurpose structures. Lightweight, low cost deicing system 16 Integrated multipurpose subsystems. 17 Develop alternative propulsion systems (ie variable compression engines, multigas generator fan system, lightweight diesel, electric hybrid, etc.). 15 Simple, effective powered-lift systems. 19 Active and passive gust alleviation systems. 20 Develop combustionbased propulsion systems for use with alternative hydrocarbon fuels (eg. ethanol, methanol, bio-diesel) that avoid octane additives and has zero net carbon increase to the environment. 21 Develop lowemission combustionbased propulsion (eg. gas turbine, internal combustion) and energy storage systems for use with nonhydrocarbon fuel (hydrogen). 22 Develop highlyefficient, lightweight hybrid electric /combustion propulsion systems with compatible energy storage systems. Develop highlyefficient, lightweight electric propulsion power generation, drive systems, and energy storage systems. 24 18 - Page 2 13 SOA = Cirrus SR-22/TCM IO-550N 25 Missions • The design mission will assist in determining the desired capability priority. – What is the vehicle design mission of interest? • Light Sport Aircraft Recreational Market – $100 hamburger, flight training, joy flights, sight seeing • Recreational Market as emergent market for future transportation choice – Gridlock commuter, fast regional transport • New aerospace commercialization opportunities in air services – Community services, homeland security, surveillance, traffic monitoring, communication, lightweight express mail delivery • If advocating a technology development program without respect for specific future applications, this is a leap of faith. – Extrapolating that aircraft should follow automotive path of hybrid to full electric is not sufficient. – Automobiles have a very different mission that makes hybrid and all electric propulsion much more attractive than aircraft (lots of idling, large efficiency losses due to part power operation, auto engine avg duty is ~25% power). 100/100 Aircraft • Achieving low emissions and decreasing dependency on oil will be a topical research area for many years – but this does not necessarily mean that electric propulsion technologies should be developed. • As part of the previous NASA PAV research, a ‘McDonalds Fryer’ environmentally friendly vehicle concept was developed to investigate the possibility of a unconventional collaborative research partner. – Goal was 100 mpg vehicle that cruises above 100 mph. – Started with a Strojnik S-3 (50’ span side by side seating sailplane) to minimize power required. – Added GSE high specific output bio-diesel engine. – Low wingloading was undesirable for handling qualities and efficient cruise was at too low of a velocity (80 mph). Investigated lower span, higher speed alternatives. – Needed greater efficiency, investigated Goldschmied propulsor (also in order to achieve lower noise without ducted prop drag). – Needed greater static thrust since Goldschmied propulsor has relatively high discloading and is only effective at thrust = drag (130% hprop) – Investigated electric auxilliary wingtip propulsor/turbines as a joint method of reducing span and increasing takeoff/climb low speed thrust. 100/100 Aircraft • Analysis results looked compelling, especially for Goldschmeid propulsor potential, however wing oversizing in cruise still limited efficiency/handling qualities. 16 100/100 Aircraft • Example 100/100 aircraft concepts utilizing GSE engine Goldschmied propulsor, with forward batteries to balance and wingtip propulsor/turbines for TO/climb. 17 Synergistic Techs High Specific Output, Efficient Bio-Diesel Engine (GSE Heavy-Fuel SIETEC Engine with Variable Compression Ratio?) 55 hp / 45 lbs .5 to .6 sfc Integral supercharger Variable compression ratio Low pressure fuel injection Multi-heavy fuel capable Compact footprint 18 Synergistic Techs Efficient, Low Noise, Low Cost Propulsor (Internal Goldschmied Propulsor with Fixed Pitch Plastic Fan?) 130% hprop at thrust = drag Muted trumpet noise effect from fuselage Single inflow velocity condition No bird strike issues Similar BLPP Experiment 19 Synergistic Techs Electric Wing Tip Auxilliary Propulsor/Turbine Cruise sized engine Wingtip mounted electric motor/alternator Auxiliary low speed thrust for TO/Climb from batteries (Ps of 1000 ft/min @ 1320 lbs = 40 hp) Battery recharge during cruise with no engine power input and no drag penalty Blades need to be symmetric with full feather capability for rotation in both directions 20 Synergistic Techs Low Cost/Maintenance Small Aircraft Highlift System (Low Pressure Electric Compressor Pulsed Circulation Control System?) Cirrus SR-22 Drag Polar FAR Part 23 Limits 0.26 L/Dmax =18 L/Dcruise = 11 Cruise ~ 0.24 21 Synergistic Techs Ease Of Use - State of the Art (System Administrator User Friendliness) Ease Of Use – Haptic Flight Control System “H”- Metaphor 22 (Mac/Windows User Friendliness) Conclusions • Research justification is for low emission alternative fuel propulsion, not electric propulsion. • Electric propulsion on aircraft must achieve synergistic integration in order to be considered, otherwise alternative approaches look better (until technology level of energy storage changes significantly to achieve parity in performance, cost and efficiency). • Technology goals for research/demonstration activity need to be developed and attached to future desired vehicle missions and desired societal capabilities. • While investigating multiple dependent technologies at the same time is failure prone, a hybrid electric propulsion aircraft may be able to manage this risk. • Opportunities exist to publish at future ATIO conference and to establish a working group in preparation for future government programs. • It is likely that primary interest (and funding) will focus on electric propulsion for small military UAVs, so any effort should indicate applicability to this application. • Other government agency funding will be scarce, so leveraging other industry efforts in this technology area (ala Tesla) is critical, especially in order to achieve any near term cost practicality.
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