Quote:
Originally Posted by freebeard
No.
There's form drag and skin friction. Aircraft strive for laminar flow but don't reach 100% (witness swing fences, etc).
Cars are immersed in time-varying microclimate turbulence and crosswinds that can exceed their velocity.
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I just wanted to make a comment about 'laminar' aircraft.
1) typically, 'laminar' would only be in reference to the wing
2) when referenced to wing and fuselage, the 'laminar' boundary layer flow is limited to the portion between the leading edge, and location of of 1st minimum pressure. Beyond this point, all boundary layer flow is turbulent boundary layer flow.
3) in the example of the Boeing 777 cargo aircraft, any laminar fuselage flow would be limited to between the forward stagnation point, and to just before where the nose forebody reaches maximum cross section width and height.
4) behind this point, all flow would be turbulent boundary layer flow.
5) unless the 777 is converted from tricycle to tail-dragger landing gear it's not a problem.
6) @ critical runway position/ airspeed- defined V2, the aircraft is required to perform elevator-induced 'rotation', which now configures the wing's angle of attack for takeoff lift.
7) with tricycle landing gear this would otherwise 'crash' the tail-boom into the runway.
8) as so, designers must 'mutilate' an otherwise streamlined boom, by scalloping it's bottom, to remove any material within this interference region.
9) a turbulent boundary layer on the bottom of the fuselage helps the air remain attached across this 'scalloped' upwards ramp, minimizing separation and drag.
10) there exists, some critical skin roughness which mimics what optimized vortex generators, in the vicinity of the tail boom would produce, to enhance this flow attachment.
11) absence of the VGs might have improved safety implications for ground crews working in the vicinity of the tail.