PPRuNe Forums - View Single Post - Acceleration check procedure for liners
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Old 14th Aug 2019, 05:09
  #21 (permalink)  
FlightDetent

Only half a speed-brake
 
Join Date: Apr 2003
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Originally Posted by hans brinker
I am going to disagree a little with some of that.
If the thrust is set for a desired (2.4 OEI) climb performance, depending on the mass of the aircraft, there would be a certain Thrust/Mass ratio. Not constant but as a function of flaps and the density altitude it should be pretty coherent. Per Sir Isaac's F=-a*m, by its mathematical definition, thrust to mass ratio IS the acceleration.

So where's the problem?

Obstacles requiring a higher than 2.4 ratio? I do not think so, with two running you'd clear them anyway.

But about the gradient: it is actually achieved by Lift /Mass, contrary to the suggestion I made above. The lift does evolve from the (square of) speed, but the required speed needs only to be achieved within the constraints of TODA/ASDA, so the acceleration required varies greatly. (lederhosen's post #12).

I still think the idea is good. Understanding the reasons why all the clever and experienced minds of yesteryear had not brought forward a solution already is part of the approach on how to crack the nut.

As a recap of the previous debates, the wide range of valid accelerations is part of the problem
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