Originally Posted by neorich2002
1.) By how much (i.e. 30% more etc) does the lift on takeoff generally exceed the weight of the aircraft. Also, when defining the maximum take off weight for an aircraft what is the regulation about providing more thrust than weight (i.e. the mtow is the weight at which the lift generated is a minimum of x% more than mtow, or something to that effect).
There's no direct regulation in Part 25 (or equivalent) that sets a minimum % of lift at takeoff.
Things that may provide hints:
Vmu could be taken as the equivalent of stall-speed for an on-ground/in-ground-effect aircraft, since it's the minimum speed you could get airborne at. FAR25.107 states (at amdt 42):
25.107 (e) (1) VR may not be less than--
.....
(iv) A speed that, if the airplane is rotated at its maximum practicable rate, will result in a VLOF of not less than 110 percent of VMU in the allengines-operating condition and not less than 105 percent of VMU determined at the thrust-to-weight ratio corresponding to the one-engine-inoperative condition.
So min Vlof=1.05Vmu (OEI) and so CL@lo=CLmu/(1.05*1.05)
So the answer is that CL at liftoff must have a margin of at least 11% below CLmu.
There's no regulation about minimum thrust, other than that the aircraft must meet the various climb gradients, which imply minimum thrust capabilities dependent upon drag, etc.