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Old 19th Feb 2018, 05:34
  #86 (permalink)  
zzuf
 
Join Date: Oct 2004
Location: australia
Posts: 215
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Well, AC 23-19A has a different take on this.

"48. What is the design maneuvering speed VA?

a. The design maneuvering speed is a value chosen by the applicant. It may not
be less than Vs√ n and need not be greater than Vc, but it could be greater if the applicant chose the higher value. The loads resulting from full control surface deflections at VA are used to design the empennage and ailerons in part 23, §§ 23.423, 23.441, and 23.455.

b. VA should not be interpreted as a speed that would permit the pilot
unrestricted flight-control movement without exceeding airplane structural limits, nor
should it be interpreted as a gust penetration speed. Only if VA = Vs √n will the airplane
stall in a nose-up pitching maneuver at, or near, limit load factor. For airplanes where
VA>VS√n, the pilot would have to check the maneuver; otherwise the airplane would
exceed the limit load factor.

c. Amendment 23-45 added the operating maneuvering speed, VO, in § 23.1507.
VO is established not greater than VS√n, and it is a speed where the airplane will stall in a nose-up pitching maneuver before exceeding the airplane structural limits."

While the FAA did not introduce a Vo for FAR Part 25 aircraft (after American Airlines Flight 587 12Nov2001), the full control deflections are about rudder, elevator and aileron structure. Careful reading of FAR 25.331 shows that at Va, with maximum elevator deflection, loads which occur beyond the limit load need not be considered.
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