Va and turbulent air penetration speed.

"Julian Scarfe" wrote in message
...

The "maneuvering speed" placarded in the cockpit is not Va. It is Vo. It
is
defined by 23.1507 and the placard is mandated by 23.1563. "Vs is a
selected speed that is not *greater* than Vsvn". My *s. At or below Vo,
the criteria that are generally (and erroneously) thought to apply below
Va,
do apply, i.e. the wing will stall before the positive limit maneuvering
load factor is exceeded.


Indeed. Vo was discussed in the thread in rec.aviation.piloting
that I referred to earlier. As I understand it, Vo is a more recent
certification requirement. Not sure then it came in, but 23.1507 is
dated 1993. My 1966 182 doesn't come with a Vo.

Certainly, terminology caused a lot of confusion the last time
this was discussed, and I expect it will again if the thread
continues!

--
Dr. Tony Cox
Citrus Controls Inc.
e-mail:
http://CitrusControls.com/

"Julian Scarfe" wrote in message
...

The "maneuvering speed" placarded in the cockpit is not Va. It is Vo.
It
is
defined by 23.1507 and the placard is mandated by 23.1563. "Vs is a
selected speed that is not *greater* than Vsvn". My *s. At or below
Vo,
the criteria that are generally (and erroneously) thought to apply below
Va,
do apply, i.e. the wing will stall before the positive limit maneuvering
load factor is exceeded.

"Tony Cox" wrote in message
news

Indeed. Vo was discussed in the thread in rec.aviation.piloting
that I referred to earlier. As I understand it, Vo is a more recent
certification requirement. Not sure then it came in, but 23.1507 is
dated 1993. My 1966 182 doesn't come with a Vo.

FWIW, here's the extract from AC23-19 (which is entirely consistent with
what you've said)

---
(c) The design maneuvering speed is a value chosen by the applicant. It may
not be less than Vs*sqrt(n) and need not be greater than Vc, but 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 14 CFR part 23, §§ 23.423,
23.441, and 23.455.

Va should not be interpreted as a speed that would permit the pilot
unrestricted flightcontrol movement without exceeding airplane structural
limits nor should it be interpreted as a gust penetration speed. Only if Va
= Vs*sqrt(n), will the airplane stall in a nose-up pitching maneuver at, or
near, limit load factor. For maneuvers where VaVs*sqrt(n), the pilot would
have to check the maneuver; otherwise the airplane would exceed the limit
load factor.

Amendment 23-45 added the operating maneuvering speed, Vo in § 23.1507. Vo
is established not greater than Vs*sqrt(n), and is a speed where the
airplane will stall in a nose-up pitching maneuver before exceeding the
airplane structural limits.
---

Julian Scarfe