The Strut Rides Again

In its next concept aircraft, Boeing floats a classic way to reduce weight.

Friday, August 11, 2023 at 12:24 PM ET

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In January, NASA contracted with Boeing to build a proof-of-concept airplane called TTBW, for Transonic Truss-Braced Wing. [Courtesy: Boeing]

Key Takeaways:

Historically, strut-braced wings were adopted by manufacturers like Cessna post-WWII for their weight-saving benefits, despite increased drag, but were later largely abandoned in general aviation due to aesthetic preferences and a shift towards higher speeds.
The fundamental trade-off between reducing structural weight through external bracing and the added aerodynamic drag has always been a critical design consideration, affecting an aircraft's overall performance.
Strut-braced wing designs are now being re-evaluated for future commercial aircraft, notably by NASA and Boeing with the Transonic Truss-Braced Wing (TTBW) project, to enable ultra-high aspect ratio wings.
This modern application aims to drastically improve fuel efficiency by significantly reducing induced drag, as struts facilitate lighter, longer wings, though the TTBW concept faces considerable engineering and logistical challenges for its practical implementation.

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The Cessna 120, introduced in 1946, bequeathed its strut-braced wings to nearly all of its successors, making struts and single-engine Cessnas almost synonymous. It wasn’t always so. In the 1930s, Cessna built airplanes like the C-34, a clean radial-engine four-seater with a cantilever wing. The demise in 1954 of the C-34’s all-metal descendant, the 190/195, left the Cessna universe to strut-braced singles. So things remained until 1967, when cantilever wings appeared more or less simultaneously on the 177 Cardinal and the 210.

This Article First Appeared in FLYING Magazine

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