Originally Posted by
Owain Glyndwr
Well I wouldn't be so sure of that - such a relationship is fundamental airmanship I think.
I'm not sure of that, but to state that thrust and AoA have no relationship is simplifying to the point of inaccuracy.
But anyway, I think you have it a bit wrong - one doesn't calculate AoA from CL but CL from AoA.
I mangled my words a bit there - apologies (I think my brain needs a cooling fan). Strictly speaking AoA and Cl are reciprocal functions of each other - i.e. a change in one will result in a change in the other. I feared going into those kind of terms would cause folk to start dozing off...
CL doesn't figure directly in assessment of whether the aircraft is near stall or not - that is a simple function of AoA and Mach Number.
Agreed - but because of the relationship between AoA and Cl and the V(elocity) component of the Cl calculation there is an indirect relationship between airspeed, thrust and AoA - that's all I've been saying.
...but even then it would be possible to work with a default value which, even if it did not prevent "stall", would serve to avoid the sort of shambles that we see in AF447.
But there we get into the quasi-religious aspect of pilot authority. While it would be possible to do such a thing, those who consider the Airbus FBW and modern FMS as a step too far* would likely kick up a hell of a stink.
Assuming that is, there is enough thrust to maintain level flight and have something left over - which is not always the case.
Well yes - if you're already at maximum thrust and you can't decrease your pitch attitude then you're in a bad way!
[* - For all people say I defend Airbus and automation, I actually think it's gone about as far as it should with the current level of technology. Technically it would be possible to go further (after all, it's been 23 years since the A320 was launched - even longer for the B757 and B767), but given the fact that business practice seems dead set on abusing the current level of automation to enact cost-cutting measures that were never intended it would be foolhardy to do so. ]