On Tue, 16 Feb 2016 03:26:42 -0800, Bruce Hoult wrote:

On Tuesday, February 16, 2016 at 3:23:18 AM UTC+3, Martin Gregorie
wrote:
1) The energy conservation law would be violated if the energy taken
from the moving aircraft as drag is less than that needed to generate
the side force.

Incorrect. Force is not energy.

If you're extracting work from the system (in this case generating a lift
force that moves the fuselage sideways) you're using energy that wouldn't
be consumed if there was no side force being generated.

This is really basic stuff: it should have been covered in School Cert
physics unless you had a really bad science teacher, and is certainly
revisited in the first year of any physics degree cause, mainly to
compensate for really bad science teachers

The only thing that aerodynamics adds to basic physics is the knowledge
that any object that generates lift also produces induced drag. There is
no induced drag if Cl = 0, but as soon is Cl is non-zero, induced drag
becomes non-zero as well and is added to the skin friction and shape-
related drag terms.



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martin@ | Martin Gregorie
gregorie. | Essex, UK
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