Flying-V: Flying long distances energy-efficiently

Re:Flying-V: Flying long distances energy-efficiently by FabHK on Tuesday June 04, 2019 @06:47PM (#20099986)

Concerning the horizontal stabiliser providing negative lift: it's possible and frequently so, but not necessary for stable flight.

(If I understand correctly, what is required is that its angle of attack is lower than the one of the main wing, or equivalently (if the wings have the same shape) its wing loading.)

See section 6.1 here, for example:

http://www.av8n.com/how/htm/aoastab.html#sec-basic-stability

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Re:Flying-V: Flying long distances energy-efficiently by nabla9 on Wednesday June 05, 2019 @07:38AM (#20103340)

Yes. That's not theoretical requirement for tailplane.

But as the source you provides say: "indeed most aircraft operate with negative tail lift most of the time."

In practice all commercial aircraft have the center of mass so much forward that require negative lift for stability. If you look at the cross section of the horizontal stabilizer, it's like wing upside down.

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Re:Flying-V: Flying long distances energy-efficiently by FabHK on Wednesday June 05, 2019 @09:24AM (#20104060)

My understanding is that airlines like to load their planes such that the CG is such that the tail contributes basically no lift, to minimise drag and fuel consumption.