B757/767 wings
G'day
I understand that both the B757 and B767 have supercritical wings, the B757 with a mach speed trim to arrest the mach tuck tendency and the B767 with a trim compensator in order to arrest any longitudinal instability, but not mach tuck, which it doesn't have a tendency towards.
The reason for the differences are that the supercritical on the B767 was moved forward on the fuselage, which brought forward the aft loaded CP and reduced the tuck tendency, whereas the B757 did not have a design compromise in wing positioning and suffers mach tuck tendencies.
Can anyone validate these interpretations?
I am also trying to confirm that the B757 and B767 both have a limiting mach number (Cd) of 0.91. For those not yet cognizant of what the limiting mach number is, I am led to believe that it is the speed at which compressibility effects begin to affect the control of the aircraft - which might be considered as the point at which you will achieve a shockstall.
One other question that comes to mind chaps:
What is actually achieved when wheel plugs melt, from a design standpoint? I realise that the tyre deflates, but what are the designers trying to achieve in deflating the tyres at this point?
Thanks in advance.