hi, i'm not the greatest expert in this field but the question of mach tuck came up at work the other day staring at the hori-stab.
An old LAME was with me while we where performing elevator free-play checks (i'm an AME at Qantas Brisbane Heavy Maintenance), i asked him why the hori stab has a percieved wash out, he told me it was for mach-tuck alleviation, i had to check wikipedia first to see what that ment. Anyway as he explained it, as the aircraft approaches critical mach, the hori stab produces a lifting moment which inturn induces an elevator control input the opposite direction. Feel free to bag me but this is the information i have, anyway no stones can hurt me as i leave oz in three days time for my first ever oshkosh .
