March 12, 2026, © Leeham News: In our series on the state of alternative propulsion projects, we are analysing where the electric hybrid projects are and how parallel hybrids work and perform.
Figure 1. The Pratt & Whitney Parallel Hybrid DH8-100 test aircraft, presently under preparation. Source: Pratt & Whitney
We summarized the status last week and compared it to the serial hybrids that we analyzed before Christmas. Serial hybrids are motivated in special cases, but in general, they make an aircraft more expensive to produce and operate.
For those who react, “But hybrid work very well for cars”?, let’s summarize: The car thermal engines are energy hogs, and you brake away all the acceleration energy at the next stoplight. Hybrids reduce this waste by recovering energy during braking. Aircraft and aircraft engines are wonders of efficiency by comparison, and there are no energy-recovery phases in an airliner mission.
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