|
|
||||||
|
|
|
|
||||
|
|
||||||
|
|
Lorenzo
Trainelli’s research Meccanica
del volo Flight mechanics
Simplified framework for airplane trim and stability Traditional basic flight
mechanics courses approach the subject of trim and stability in a somewhat involved way,
tracing back from a preliminary design approach. The typical learning path
consists of a step-by-step
process from the airfoil, to the isolated wing, to the wing-body, ending with
the ‘complete’ airplane. Correspondingly, the
formulae – although mathematically simple – gradually get considerably unattractive
and uneasy to remember, being `cluttered' by a remarkable amount
of quantities that describe specific details of the assumed airplane model. A considerable simplification
can be achieved by stating the general aerodynamic constitutive laws pertaining to
the relevant flight conditions (stick-fixed steady level flight, stick-free
steady level flight, steady maneuvering flight, etc.), under the customary
assumptions of linear, low subsonic, steady-state aerodynamics. From the
investigation of the constitutive laws, appropriate characteristic points are
introduced: the first is the well known neutral point, while the second is
termed the control point (the
latter, for a traditionally tailed design, is located close to the
aerodynamic center of the tailplane). We end up with
the reduction of the complex system of aerodynamic forces acting on the
airplane to an equivalent one consisting in only two applied forces: the
first, termed the attitude lift,
depends on the angle of attack only, while the second, termed the control lift, depends on the elevator
deflection only. As a consequence,
basic considerations of trim and stability are easily carried out by simple, intuitive
reasoning upon a simplified force diagram. I contributed in this
work originated by prof. M. Borri. This methodology is
detailed in the following works:
|
|||||
|
|
|
|||||
|
Last updated 19/09/2006. |
||||||
|
|
||||||
