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Old 21st Sep 2022, 02:51
  #115 (permalink)  
fdr
 
Join Date: Jun 2001
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As suggested previously, when encountering the longitudinal stability issue, Boeing could have completed aerodynamic mods to the design to remove the anomaly, which resulted from the nacelle adding lift to the wing/nacelle structure that was more than anticipated. That alone would have suggested that an angle grinder should be taken to the strakes to trim their nose hair a shade. Instead, they came up with a neat trick to change a high speed design that had questionable redundancy on trigger events to being low speed too by removing one of the two trigger conditions which gave a single point of failure as a matter of certainty. As AOA probes have a fairly modest MTBF in use, that wasn't a great concept.

Here is a set of charts that show the effect of having strakes or not, which would have been a relatively minor change to the aircraft. As the engines are inboard, it is a matter of certainty that reducing the section CLmax proximate to the nacelle would have ended up in an improvement in the stick force/g. Being judicious, the effect to Vs1g would have been quite modest, and surely, please surely the OEM noted that the stall speed was curiously lower with their design than expected, otherwise, they need a serious boot in the bottom of their trousers for being myopic.


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