A dynamic model for aircraft poststall departure

An engineering model designed for the analysis of high angle-of-attack flight characteristics is developed and applied to the problem of aircraft poststall departure. The model consists of an aerodynamics package used interactively with a six-degree-of-freedom flight simulator. The aerodynamics are computed via a nonlinear lifting line theory with unsteady wake effects due to a discrete, nonplanar vortex system. A fully configured aircraft (main wing, horizontal tail and vertical fin) is mathematically constructed by modeling all lifting surfaces with bound, discrete vortex segments and associated control points; vehicle geometric influence on high angle-of-attack flight characteristics is included through complete variability in the relative locations, orientations and sizes of the flight surfaces. This aircraft model is “flown” through prescribed maneuvers by integrating the equations of motion. Selected results of trajectory simulations presented for a typical general aviation aircraft provide the following insights to wing-drop departure subsequent to stall. The abruptness of poststall roll-off depends on the presence of flight asymmetries at the stall break and the rate of stall penetration. Such out-of-trim flight conditions induce asymmetric wing panel unstall subsequent to deep stall penetration resulting in large wing-drop-producing roll moments. However, the abrupt departure from symmetric flight conditions is also found to be mathematically possible. This is a consequence of multiple lifting line solutions which exist for bound vortex systems assigned the lift properties of airfoils having stall discontinuities. The dynamic model is well suited to the prediction of departure resistance benefits realized through passive aerodynamic modifications, for example, drooped leading edge outboard wing panels. The model can also be applied to the generation of dynamic stability derivatives by analytically simulating forced oscillation test procedures.

Name thesis:degree_name

Ph. D.

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Aerospace and Ocean Engineering

Department dc:contributor.department

Aerospace and Ocean Engineering

Grantor dc:publisher

Virginia Polytechnic Institute and State University

Year dc:date.issued

1982

Author dc:creator

• Hreha, Mark A.

Chair dc:contributor.committeechair

• Lutze, Frederick H.

Committee members dc:contributor.committeemember

• Cliff, Eugene M.
• Kelley, Henry J.
• Marchman, James F.
• Burns, John A.

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en_US

Handle dc:identifier.uri

http://hdl.handle.net/10919/76592

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/76592