Hybrid VTOL: Increased Energy Density for Increased Payload and Endurance Top Flight Airborg 10K H8 with Micro Hybrid Generator Engine Dr. Paul DeBitetto, VP/Software Engineering, paul.debitetto@topflighttech.com, 781.258.9405 0
Drone Revolution: A paradigm shift for VTOL Design Multirotor drones account for approx 96 percent of flights for commercial and industrial purposes, (study by DroneDeploy) 1
Why? Multi-rotors are considerably simpler 2
Latest VTOL aircraft designs are taking cues from consumer drones! Airbus Vahana Project NASA X-57 Concept E-Volo Velocopter 2X AirspaceX MOBi Aurora VTOL Moller International Skycar 400 Terrfugia TF-X EHang Air Taxis 3
Houston, we have a problem. Fuel kwh/kg $/kwh Li Battery 0.15 0.11 Goose Fat 8.40 0.89 Kerosene 12.3 0.07 Gasoline 12.9 0.07 Natural Gas 9.80 0.02 Hydrogen 32.8 1.56 Battery energy density is still small compared to other fuel sources Batteries are heavy and they don t get lighter as they deplete! Power Req: 160 hp, 119 kw Max Load: 200 kg Approx batt wt: 800 kg 19 gal x 6.8 lb/gal x.45 kg/lb = 58 kg gasoline Empty wt: 400kg Robinson R22 UH-60 Blackhawk Power: 362 hp, 270 kw (base model) Battery: 60kWh / 150W-hr/kg = 400 kg Tesla Electric Car Poqwe Req: 2x1800 hp, 2685 kw Max Load: 1200 kg Approx batt wt: 17900 kg Empty wt: 4800 kg 360 gal x 6.8lb/gal x.45 kg/lb = 1100 kg of jet fuel 4
Why Batteries Alone Won t Fly Battery Challenges: Drones need to fly hours with significant payloads to expand into many real applications. Practical fast-discharge batteries in a package suitable for flight today weigh in at about 150 Wh/kg. Moore s Law does not apply to battery innovation. Improvements are expected to be incremental and linear. Meanwhile, electric batteries take time to charge, degrade over time, and are expensive. They present storage and end-of-life recycling challenges. New Solution Hybrid New Benefits: Combine the gasoline engine, a generator, and a much smaller battery and you get the best of both worlds. This solution fuses the portability and instant power availability with the high energy densities of gasoline while benefitting from the design flexibility of electric flight. Need a path to higher payloads, longer endurance. Larger, more powerful, higher reliability, lower system cost!! source: DOE JCESR The auto industry targets battery cost reduction to $100/ kwh in 2022. 5
Key Benefits of Hybrid Electric Technology Why Hybrid Electric? Fuel specific energy is about 75 times higher than batteries. At 20% conversion efficiency, it is still 15 times that of practical battery packages. A hybrid system eliminates time spent on a charger. Cost? Cost of (engine/overhauls + fuel) is on par with cost of (batteries + electricity). Reliability? Engines have a long track record and wellunderstood reliability plan. Compare that to fast-discharge batteries operating over large temperature ranges. Battery vs. Gasoline Tradeoffs Advantages Disadvantages Energy Density (Wh/kg) Batteries Rechargeable Low Energy Density ~200-250 Energy Conversion Efficiency Takes Time to Recharge Reliable Available in High Quantities High Power Availability Silent Operations Charging Inefficiencies Safety Issues Gasoline High Energy Density Requires Power Conversion ~12,700 Readily Available Fuel Extra Weight for Power Conversion Wide Operating Temperatures Environmental Pollution Reliable Energy Source Loud Operation 6
A Working Example System estimates for a multirotor capable of 30 minute flight with 100 kg payload. The batteries in the hybrid systems are sized for 4-minute emergency landing. Batteries scale very unfavorably for flights longer than this. Piston Hybrid Recuperated Turbine Hybrid Battery Electric Flight Duration 30 min 30 min 30 min Engine/Generator Volume (L) / Mass (kg) 125 L / 115 kg Fuel Volume (L) / Mass (kg) 25 L / 19 kg Battery Volume (L) / Mass (kg) 22 L / 44 kg 80 L / 90 kg 17 L / 13 kg 22 L / 44 kg X/X X/X 208 L / 417 kg Total Power System Volume (L) Total Power System Mass (kg) 172 L 160 L 208 L 178 kg 137 kg 417 kg 7
Lithium Ion Battery Challenges: Safety Energy density, heat management, and safety. Battery power-to-weight ratio not sufficient to power a man-carrying vehicle for more than a few minutes at a time Heat: batteries dissipate heat. Cooling solutions albeit active like liquid coolers or passive like heat sinks add weight. Safety: You regularly hear about laptops or aircraft batteries catching fire. It is not uncommon. https://youtu.be/jecjagrsp-4 8
A Modular Approach to Aviation Design Hybrid Electric: for now, best of both worlds Decouples the Mechanical Systems in Traditional Aviation Design Reduces Complexity, Part Count, Repairs, MRO A Modular Approach to New Aviation System Design (LEGO-like) Energy/Power Systems Easily match system power to program Significant Auxiliary Power for: Avionics Sensing/Computer Power Communications Payload balancing Pilotless/Autonomous 9
Hybrid Engine Challenges ( 2017-2030) Building Hybrid Engines is NOT easy Designing high power to weight ratio Energy conversion efficiency (e.g. no gearbox) Magnetic field generation & magnetic field control (motor technology) Power & energy management (distribution, AC/DC Conversion, safety) The Never Ending Challenges Heat & Vibration! High energy density = high RPM = Problems (24000 RPM for turboshaft engine) Examples: coupling methods, material wear, overheating component qualification and life cycle definitions 10
TFT Hybrid vs Honda 10,000 Watt Generator TFT Hybrid 10kW Honda EB10000 Weight (kg) 8 kg 183 kg Max Power Output 10,000 W 10,000 W Size (inches) 13 x13 x13 55 x27 x35 Efficiency (100% Power) 2000 Whr/kg 1700 Whr/kg Efficiency (50% Power) 1500 Whr/kg 1333 Whr/kg 11
Scaling Top Flight Technologies Power System Roadmap Future Power Roadmap 1 MW Engine (Gas Turbine) +40 Months 250kW Engine (Piston/Gas Turbine) 100kW Engine (Piston) +20 Months 10kW Engine (Piston) Today TODAY (March, 2017) Scaling Engines for More Power More Power = More Efficiency Transition from Piston to Gas Turbine at 250 kw Piston is viable up to 250 kw Gas Turbine is viable beyond 250 kw < 40 Months: 250 kw 1 MW HE Engine 250 kw 1 MW of Total Power 250 1000 kg of Payload 3+ Hours of Endurance 20-50% Efficiency, 60k-120k Ultra High RPM Engine ONLY < 20 Months: 100 kw HE Engine (Piston) 100 kw of Total Power 100 kg of Payload 3+ Hours of Endurance 20-25% Efficiency Engine + Platform TODAY: 10 kw HE Engine (Piston) 10 kw of Total Power 4 kg of Payload 3+ Hours of Endurance 20% Efficiency 12
Airborg H8 10K Hybrid UAV A Next Generation Platform with Extraordinary Technology Trade-Space for Payload, Endurance, Power Availability, Computing, Sensing, & Communications Capabilities Up to 3 hours fight time with 4 kg payload using standard power-plant Up to 1 hour flight time with 10 kg payload using standard power-plant Payloads over 10 kg possible with enhanced power-plant option Built in battery backup and engine self starting in case of in flight engine failure. Up to 2 minutes of flight time under battery power for safe landing and recovery. Built in 5V DC and 12V DC payload power (100 W total). Other DC voltages and power levels available upon request. Redundant design for high reliability 8 lift motors in standard Quad layout provides for safe and stable operations. Optional partial and full shroud kits available. All components are modular for easy field replacement Prop arms are removable for convenient packing and transport Self starting Flexible payload mounting options Various sensor and navigation packages available 13
What We Solve for Drones/Robots: Endurance Payload Power 14
Challenges for autonomous VTOL aircraft FAA Regulations No drones > 55 lbs No air traffic control for autonomous vehicles o About 87000 aircraft flights per day in US o About 250 Million cars hit the road each day. Safe Autonomy Commercial aircraft are largely autonomous o Environment is highly structured Autonomous cars are still in infancy stage o Extremely challenging, unstructured and unpredictable environment Energy Density Distributed electric powered aircraft are coming, but battery technology is not progressing fast enough o Zero emissions, high power to weight rating, high efficiency, simplicity, scalable, and very little noise or vibrations. 15