Is it possible for an airliner to safely fly with doors open? From another question asks about the possibility of dropping bombs from converted airliners. My question: is it possible to safely fly aircraft with a door open for the whole flight envelope? Would the aerodynamics be affected if we did not close the door?

I am not asking about the need of oxygen for the crew, just about the aerodynamics involved. I know the plane would not be pressurized.
The Stratospheric Observatory for Infrared Astronomy (SOFIA) is a modified 747 that has an 5.5 m x 4.1 m door that is opened during flight for the installed in infrared telescope. But the door is usually closed during takeoff and landing.

But according to this story there are emergency procedures to land with an open door and it had to do so once, when it became stuck half open.



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