Aerodynamics is so complicated compared to other disciplines

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Turd Ferguson

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Don't most cruise at just above stall?
I think it would be generalizing to say "most." Perhaps "some" would be more appropriate; At work they were smart enough to recognize my limitations and assigned me to "Jets for Dummies."
As you can see, close to the maximum altitude (41,000) at planned cruising Mach number, there is a generous buffet margin envelope. All the planes I've been in with advanced supercritical wings fly like this. I noticed when riding in the jumpseat of an MD 88 the margin was somewhat narrow at FL340. Not sure how high it can fly but that was the highest it could go on that day.


PFD.jpg



Why? From a non-aero engineer, I would expect them cruise at the highest L/D.
The only time we would fly near L/Dmax would be for endurance because in a jet powered airplane, max endurance occurs at L/Dmax. Of course, the performance chart won't allow flight exactly at L/Dmax because of inadequate buffet margin so it's typically about 25% faster. If you need to maneuver, the extra speed provides stall protection for up to 25* of bank.
 
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Himat

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https://www.youtube.com/watch?v=QKCK4lJLQHU

Dough McLean, retired Boeing Technical Fellow on fire debunking a lot of even elaborate theories of aerodynamics. It's worth 48 minutes of your life. Be forewarned it is full geek at full throttle.

Enjoy.
And I got the book as a birthday/Christmas gift from my sister this year.:ban:
I just have to wait until Christmas before official opening of the gift and start reading.
 

Swampyankee

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