Accession Number:

ADA244051

Title:

Analysis of an Advanced Fighter Aircraft Using Jet Flap Techniques and the Vortex Lattice Method

Descriptive Note:

Master's thesis,

Corporate Author:

AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING

Personal Author(s):

Report Date:

1991-12-01

Pagination or Media Count:

137.0

Abstract:

A computer code using the vortex lattice method with modified boundary conditions was used to determine the induced aerodynamic characteristics of high aspect ratio, vectoring, exhaust nozzles located at the wing root of a canard configured fighter aircraft. Comparison with existing wind tunnel data verified results of the method. The exhaust was modeled as a singularly blown jet flap at deflection angles of -10, 0, 10, 20, 30, and 40 degrees. Jet momentum coefficients were based on gross engine thrust for maximum afterburner and military power settings at a Mach number of 0.6 and an altitude of 20,000 ft. Lift, induced drag, and pitching moment coefficients were calculated for untrimmed conditions. The nozzle provided lift augmentation at all deflections and blowing conditions, a reduction in induced drag at high lift coefficients, and an increased nose down-pitching moment. An optimum flap deflection to achieve minimum induced drag existed for each unique lift and blowing condition. Measurement of the static margin showed that the aircraft as configured was statically unstable. Example cases of comparable wing platforms varying in aspect ratio from 2 to 5 and taper ratio from 0.05 to 1 showed similar behavior.

Subject Categories:

  • Aerodynamics
  • Attack and Fighter Aircraft

Distribution Statement:

APPROVED FOR PUBLIC RELEASE