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Classic Theory Meets Digital Computer; Status Quo Emerges Unscathed

A 45-year-old essay about 'Carson Speed' became a point of reference for the wonkier class of pilot.

It turns out that the 'Carson Speed' is a very blunt instrument. [Adobe Stock]
Gemini Sparkle

Key Takeaways:

  • B.H. Carson's paper introduced "Carson Speed," a theoretical aircraft cruise speed (1.32 times the best L/D speed) designed to maximize time savings for the least excess fuel consumption.
  • Carson's model overlooked real-world engine and propeller efficiencies, which improve at higher power settings, shifting the actual optimal speed (the "Real Carson Speed" maximizing speed and mpg) higher than his theoretical calculation.
  • However, simulations reveal the speed-mileage efficiency curve is broad, indicating that while the "Real Carson Speed" is higher, flying at common, slightly faster cruise settings (e.g., 60-75% power) still yields high overall efficiency with only minor penalties.
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The late B.H. Carson’s AIAA paper on “Fuel Efficiency of Small Aircraft” emerged unsought, like a dinosaur bone poking out of eroded Wyoming topsoil, from the scree of papers on my desk.

First published 45 years ago, Carson’s essay became a point of reference for the wonkier class of pilot, to whose vocabulary it contributed a couple of novel phrases: “Carson Speed” and “the least wasteful way of wasting.”

Peter Garrison

Peter Garrison taught himself to use a slide rule and tin snips, built an airplane in his backyard, and flew it to Japan. He began contributing to FLYING in 1968, and he continues to share his columns, ""Technicalities"" and ""Aftermath,"" with FLYING readers.

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