Hybrid Electric Aircraft Technologies and Alternative Fuels

NASA is developing a new hybrid-electric aircraft concept called the Subsonic Single Aft Engine (SUSAN) Electrofan. SUSAN uses 10MW class Electrified Aircraft Propulsion to Enable advance Propulsion Airframe Integration (PAI) in transport category aircraft. The aircraft will use alternative fuels to reduce the amount of emissions per energy used. Combining these features may reduce aircraft emissions by 50% per passenger/mile while retaining the size, speed, and range of large regional jets. This focus area seeks companies that wish to partner on technology that can be used in a 25% scale Group 3 size unpiloted demonstration aircraft under consideration. Required technologies include electrical power systems, batteries, thermal management systems, alternative fuels, and advanced electric propulsors. 

Of specific interest to NASA are technologies with a viable risk reduction path through ground and flight testing within two years. These technologies should have the ability to potentially transition into the large uncrewed aerial vehicle market ($18B with a 12% growth rate) or the emerging air taxi and small electric plane markets. Technologies relevant to the SUSAN demonstrator should have the potential to be built and integrated into the aircraft within one year.  

Nominal requirements for the components are:

• Generator – 100 kW capable of powering four independent 100V DC buses 
• Energy Storage – Capable of providing a minimum of 100 kW over five minutes 
• Wing mounted propulsors – 5-10 kW 
• Aft thruster – 75kW high propulsive efficiency in fuselage wake 
• Alternative Fuel Hybrid Engine – 150kW split 50%/50% between aft fan and generator 
• Fuel Storage – should allow two hours of continuous full-power operation of the engine  

Evaluation factors of specific interest include:

• Impacts on aircraft design
• In-flight and total lifecycle emissions reduction relative to Jet-A fuel
• Scalability of the proposed fuel to utilization by the entire commercial aviation fleet
• The land and water use required to produce the alternative fuel
• Fuel production, distribution, and aircraft fueling/handling infrastructure needs
• Areas of the globe best positioned to produce alternative fuels.