offset the disparity between electric and gasoline energy densities. Electric motors also do not lose power with altitude, unlike internal-combustion engines, avoiding the need for complex and costly measures used to prevent this, such as the use of turbochargers. The experimental Extra 330LE have a Siemens SP260D motor weighing 50 kg, with a kWh battery pack, for an aircraft weight of 1,000 kg. It replaces a 235 kW (315 hp) Lycoming AEIO-580 piston engine weighing 202 kg. The piston-engine Extra 330 empty weight is 677 kg, kg without the engine. The Lycoming engine has a fuel consumption of per hour when outputting , or kg/kWh: it needs kg of fuel to output the same 37.2 kWh. Besides the motor itself, an aircraft weight is hampered by the necessary energy reserves: a 19-seat aircraft needs the mandatory IFR reserves of 5% route contingency, the flight to a 100 nmi alternate plus 30 minutes of holding before landing – 308 kg of fuel for a turboprop, or 4,300 kg of 250 Wh/kg batteries, similar to a current 19-seater empty weight. An electric propulsion system also includes a power inverter, while fuel engines have a fuel system themselves. The experimental magniX magni500 electric motor weighs , while the certified Pratt & Whitney Canada PT6A-114 weighs , both powering the Cessna 208 Caravan. The increase in power, combined with Supplemental Type Certificate (STC) modifications can offset the weight of the batteries by increasing the airplane's gross operating weight, including the landing weight. Aircraft that use fossil fuels are lighter when they land, which allows the structure to be lighter. With a battery powered aircraft, the weight remains the same, and so may require reinforcement. Hybrid power A hybrid electric aircraft is an aircraft with a hybrid electric powertrain. It typically takes off and lands under clean and quiet electric power, and cruises under conventional piston or jet engine power. This makes long flights practical, while reducing their carbon footprint. By May 2018, there were over 30 projects, and short-haul hybrid-electric airliners were envisioned from 2032. The most advanced are the Zunum Aero 10-seater, the Airbus E-Fan X demonstrator, the VoltAero Cassio, UTC is modifying a Bombardier Dash 8, while the Ampaire Electric EEL prototype first flew on 6 June 2019. Magnetohydrodynamics In November 2018, MIT engineers achieved the first free flight with a model aircraft having no moving parts, the EAD Airframe Version 2.