Load tests and moments evaluation of aircraft pylon using refurbished test assembly
Subas Chandrabose Satheesh Kumar
Date of Issue2014
School of Mechanical and Aerospace Engineering
An aircraft pylon is a suspension device under the fuselage or wing of an aircraft used to attach and carry missiles, gun pods, propulsion units, fuel tanks etc. The component-loaded pylon experiences considerable loads in yaw, pitch and roll during the corresponding aircraft flight manoeuvres. It is deemed necessary to have reliable test facility and methodology, and accurate load estimation procedure that can establish on ground the load coefficients for a pylon useful for arriving at various loads during the aircraft flight. In this dissertation, a non-jettisonable pylon of F- 16 Aircraft used for carrying an external fuel tank or store (600 gallons capacity), is studied. The pylon, which has been the specimen of this experimental stud y, is equipped with st rain gauge bridges to monitor the loads transferred between the fuel tank and the pylon structure. It was ensured that the test rig, although portable, was able to facilitate 13 predefined load cases without any distortions, lifting and deformations in any of its sections. Some of the important details are presented. Experiments were conducted as specified by the OEM report  and each strain gauge bridge response was monitored for different levels of (20 to 100%) loading for the all 13 load conditions. The methodology established for determining load equations and load coefficients (s lope and probable error) in pitch, roll and yaw using the obtained strain gauge data is explained. The strain gauge information was analysed using a MATLAB program written for this purpose. The load coefficients thus accomplished are specific to the pylon and the suspended load, and their trends, relationships, the effect on them of change in strain gauge locations are discussed. Additionally, a similar exercise is conducted using ASYS, a genera l-purpose FEA software, and findings are compared with the test results. Other inferences and deductions drawn from this study are deliberated. Apart from that, two different approaches for reducing the probable error are also attempted.