Date of Award

3-22-2012

Document Type

Thesis

Degree Name

Master of Science

Department

Department of Aeronautics and Astronautics

First Advisor

Andrew J. Lofthouse, PhD.

Abstract

Both the RC-135V/W Rivet Joint (RJ) and the RC-135U Combat Sent (CS) aircraft are United States Air Force (USAF) electronics reconnaissance platforms. The RJ is the USAF's standard airborne signals intelligence (SIGINT) gathering platform, while the CS is designed to collect technical intelligence on adversary radar emitter systems. Both aircraft are extensively modified C-135's characterized by protruding cheek fairings along the sides of the fuselage forward of the wings as well as the addition of numerous antennas along the top and bottom of the fuselage. The major distinguishing feature between the two variants is the nose radome, wherein the RJ has an elongated nose while the CS has the standard C-135 nose with a protruding chin radome along the underside. The RJ has recently experienced problems with antenna buffeting resulting in broken antennas and damage to the aircraft. Flight testing confirmed the presence of unsteady loading on certain antennas that has been traced back to the turbulent exhaust flow of a liquid cooling system (LCS) installed in the forward cheek fairings. Both variants have this modification but only the RJ has experienced structural damage. Computational fluid dynamics (CFD) was applied with the intention of characterizing the differences between the two variants. The LCS mass flow rate, angle of attack, and configuration of each variant was altered and results compared. Slight differences in the flowfield about each variant were noted with very similar turbulent fluctuations observed with the LCS installed. A strong correlation to angle of attack was confirmed while a weak correlation to mass flow rate was discerned.

AFIT Designator

AFIT-GAE-ENY-12-M06

DTIC Accession Number

ADA561659

Download

Share

COinS