Aerodynamics and the mysteries of "why"..

Thank you Bob for clearing up that visual/geometric mystery!

 

Do I detect some kidding here?

 

Nope, 100% serious. I am car designer and have noticed that flat spot the first time I saw the plane in real. I wondered if the reason for it was to 1) reduce frontal area/drag and 2) reduce the blocking of the vertical stab by the fuselage with positive angle of attack.

 

Thanks, I do get kidded about it when I mention it to the uneducated but my partner and I worked on the Catia for a long time trying to get it to work when it was "pretty" but it didn't like the airflow. So, it was strictly just that, an airflow problem. It's funny stuff sometimes.

 

We really should educate the airflow to like pretty shapes!
And follow the arrows the stylists draw on the sketches.

Catia is a challenging tool when it comes to making shapes aesthetically pleasing. Alias and IcemSURF (now part of the Catia package) are the preferred tools in the car industry.

 

We ran a Goushen (SPL) airflow analysis on the pretty curve and got a glaring red band at the apex and we had to keep whittling the curve down until it quit. Very strange to end up with an unpretty curve. That whole exercise was to try to save some money in matching the entire 767 windshield cage and cab to the 777 fuselage that is higher and wider. Finally we threw away the 767 cab except for the windshield cage and went with an entirely new cab loft. In 1990 we broke a lot of new ground with the CATIA and pioneered a few things. I have three or four commendations from the big boss for the work that we did. (For once, I didn't say condemnations .)

 

Sounds like the car industry... Thank you for your insights!