EnergyTech2015.com Track 2 Session 3 HYBRID ELECTRIC POWER FOR AERONAUTIC PROPULSION PANEL Moderator: Michael Heil, Ohio Aerospace Institute This panel will explore benefits and technology challenges associated with distributed, hybrid electric propulsion for future subsonic aeronautic vehicles. Panel members will include aeronautics propulsion industry, NASA, and the DoD. James Felder, NASA Glenn Research Center John Nairus, Air Force Research Lab, Chief Engineer Power & Controls Division Neil Garrigan, GE Aviation Meyer Benzakein, OSU - Aeronautic

1. 1
Integrity  Service  Excellence
Hybrid-Electric
Propulsion
Energy Tech 2015
30 Nov 2015
John Nairus
Chief Engineer
Power & Control Division
Aerospace Systems Directorate
DISTRIBUTION F. Further dissemination only as directed by AFRL/RQQ,
1950 Fifth Street, WPAFB, OH 45433-7251 (Nov 2015).

2. 2
Power & Thermal – The Problem
• 6th Gen mission systems need
more electric power
– Advanced Radar systems
– Special Mission Loads (DEW, EA, EW)
• Power is increasingly flight critical
– 4th Gen  Flight control computer
– 5th Gen  Added actuation power
– 6th Gen  Mission systems
• More power equals more heat
– Advanced LO aircraft have limited
heat dissipation options
• Efficient engines provide less fuel for heat sink
• High power extraction could affect engine
operability
DISTRIBUTION F. Further dissemination only as directed by AFRL/RQQ, 1950 Fifth Street, WPAFB, OH 45433-7251 (Nov 2015).

3. 3
5th vs. 6th Gen Aircraft
• 5th Gen aircraft today have ~250KW installed
electrical power capability
• 6th Gen aircraft concepts desire 1000KW peak
Mission system duty cycles
are highly variable
6th Gen
Power for 1000 homes (6-10x)
Power for 150 homes
5th Gen
DISTRIBUTION F. Further dissemination only as directed by AFRL/RQQ, 1950 Fifth Street, WPAFB, OH 45433-7251 (Nov 2015).

4. Turbo-Electric Efficiency & Weight
2015
Conventional
Turbo-Electric (2015 Technology)
vs
Propulsor Efficiency
Efficiency Improvements from
Boundary Layer Ingestion (drag/air
frame/engine integration)Conventional Propulsion System Efficiency = 39%
Turbo-Electric Propulsion System Efficiency (2015
SOTA) = 36% (Turbine * Electric * (Prop + BLI))
Weight of Conventional Propulsor (2015
SOTA) = ? lbs
Electrical Weight of Turbo-Electric Propulsor (2015
SOTA) = 75,000lbs
(Does not include
distribution wire weight,
circuit protection)
Notes:
- Turbo-Electric and conventional propulsion use 55% efficient turbine engine
- More-Electric secondary power will result in 3-5% improved aircraft fuel efficiency
vs. conventional secondary power regardless of propulsion system (not included in
above propulsion efficiency calculations)
- High voltage distribution voltage/wire weight for aircraft still needs to be
addressed
assume 1lb thrust = 1hp
DISTRIBUTION F. Further dissemination only as directed by AFRL/RQQ, 1950 Fifth Street, WPAFB, OH 45433-7251 (Nov 2015). 4

5. 5
Turbo-Electric Efficiency & Weight
Future Example
Turbo-Electric (Future Technology)
Propulsor Efficiency
Efficiency Improvements from
Boundary Layer Ingestion (drag/air
frame/engine integration)Conventional Propulsion System Efficiency = 39%
Turbo-Electric Propulsion System Efficiency (2015
SOTA) = 46% (Turbine * Electric * (Prop + BLI))
Weight of Conventional Propulsor (2015
SOTA) = ? lbs
Electrical Weight of Turbo-Electric Propulsor (2015
SOTA) = 18,750lbs
(Does not include
distribution wire weight,
circuit protection)
Notes:
- Turbo-Electric and conventional propulsion use 55% efficient turbine engine
- More-Electric secondary power will result in 3-5% improved aircraft fuel efficiency
vs. conventional secondary power regardless of propulsion system (not included in
above propulsion efficiency calculations)
- High voltage distribution voltage/wire weight for aircraft still needs to be
addressed
Conventional
vs
assume 1lb thrust = 1hp
DISTRIBUTION F. Further dissemination only as directed by AFRL/RQQ, 1950 Fifth Street, WPAFB, OH 45433-7251 (Nov 2015).

6. 6
Thoughts…
• “Hybrids Always Win”
– Richard Quigley, Director, Propulsion Directorate, Air Force Research Laboratory, circa 1999
• Turbo-Electric propulsion includes gas turbine engines
• Trade studies must look at total aircraft, not just
propulsion system (i.e. thermal management)
• Hybrid/turbo-electric propulsion is being pursued for
unmanned aircraft
– Fuel cells, batteries, motors, engines, turbo-generators
• Challenges: Megawatt-class aircraft power systems vs.
conventional and more electric
– Size/weight/cost/reliability
– Scale-up of unmanned hybrid/turbo-electric to commercial aircraft
(technical and cultural)
DISTRIBUTION F. Further dissemination only as directed by AFRL/RQQ, 1950 Fifth Street, WPAFB, OH 45433-7251 (Nov 2015).