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Old 24th Apr 2012, 18:00
  #16 (permalink)  
Join Date: Oct 2006
Location: London
Posts: 424
Out of interest, what is the engineering reason bizjets are designed for typical optimum cruise in the mid 40s and airliners in the mid-high 30s?

The higher a jet goes the lower the specific fuel consumption? So higher is better. But, I guess the negatives for this are the airframe penalties for operating at a higher level (in terms of higher press. diff.) and relatively higher thrust engines to be able to achieve the climb. But then both these trade-offs seem to me to scale up and down across transport jets and bizjets? Is it that the bizjet operators prefer shorter runway capability, so the greater SL thrust has other benefits? Or is it wing related - something like a long slender wing optmised for very high levels is structurally too heavy if scaled up to airliner size? I don't know if there are certification issues with high levels that are more easily met in a smaller aircraft? I can't think what they might be, it feels like the smaller aircraft could depressurise much faster, so it's not "speed of pax accessing emergency oxygen" thing.

Sorry if this rambling question has misunderstood the technicalities!

Last edited by 421C; 25th Apr 2012 at 12:04.
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