Possibly re-regoing over old ground here but Figure 6 from the following NASA report stands out to me ... (thanks to BJ-ENG for posting the link)
http://ntrs.nasa.gov/archive/nasa/ca...2005208658.pdf
So, from the wind tunnel data for this generic-ish twin engined commercial aircraft, we have a family of curves showing the relationship between pitching moment and AoA for elevator angles from -30 deg to +20 deg, all at a zero HS angle and CG mid.
How about we then factor in a typical HS cruise trim angle and aft CG and consider what sort of AoA value might start becoming a nasty place to be?
From page 4 (Section B) of the same document:
1. Static Pitch Stability
Aerodynamic pitching moment characteristics from the
wind tunnel tests are shown in Fig. 6. This figure shows the
variation in static pitch stability and elevator control
effectiveness over the angle of attack range. The
configuration is statically stable at low angles of attack as
indicated by the negative local slope of pitching moment
coefficient with angle of attack. However, in the stall region
(
α≈10°-14°), the stability is reduced generally due to
combined effects of outboard wing stall and downwash
interactions with the horizontal tail. The pitch control
remains effective throughout the angle of attack range but
diminishes with increasing angle of attack, due initially to
the immersion of the horizontal tail in the wing wake and
ultimately due to flow separation on the horizontal tail itself
at post- and deep-stall angles of attack. The maximum
steady angle of attack with full nose-up elevator deflection
is at
α≈25°, which is significantly higher than the stall
region near
α≈12° and this result indicates the potential for
the airplane to enter upset conditions using normal pilot
controls during un-accelerated flight.
Edit: added aft CG