M.Sc Thesis

M.Sc StudentShitrit Dor
SubjectThrust Vectoring and Aft Burner System for Increasing
Survivability of Micro Jet UAVs
DepartmentDepartment of Aerospace Engineering
Supervisor PROFESSOR EMERITUS Yeshayahou Levy
Full Thesis text - in Hebrew Full thesis text - Hebrew Version


A major current threat on Unmanned Aerial Vehicles (UAVs) and Air-to-Surface Missiles (ASM) is being intercepted by Surface-to-Air Missiles (SAMs) with maneuvering capabilities. There are many methods to increase the survivability of such UAV and ASM while the challenge is keeping them cost-effective and relevant to the modern battlefield.

One of the ways to increase survivability is by improving agility. Agility of an aircraft can be improved by using thrust vectoring and activation of an after burner. It enables the platform to accelerate by operating the aft burner while vectorizing the thrust - thus “breaking lock” from the potential threat.

This study aims to investigate such integration in micro turbo jet UAVs. It includes dynamic simulation of the after burner as well as the vectoring nozzle systems and their effect on the aircraft overall performance. A total of 3 engine power configurations (basic with constant nozzle, adjustable nozzle, adjustable nozzle with aft burner) and 2 vectoring configurations (with/without) are examined.

For this purpose, Dornier "DT-45" UAV and "SA7-Strella" SAM are chosen as target and interceptor demonstrators. Complete engine decks are created including designing engine control system to withstand the engine limitations during the transient state. Drag polar, stability & control derivations of the target and interceptor main characteristics are estimated. Evasive maneuvers are characterized, and a dedicated aircraft control system is implemented to support it.  Finally, a quantitative analysis for the joint contribution of thrust vectoring and after burner to the survivability of the aircraft is introduced by implementation of interception simulation. The analysis is conducted in subject to every engine power configuration with and without thrust vectoring capability and the feasibility of implementation of such system is discussed.

The main results indicate that after burner and thrust vectoring systems have a potential for increasing miss distances thus survivability. Although, there can be engagements in which these capabilities will not succeed to save the aircraft from hit. The most significant improvement in miss distance is accepted with after burner and thrust vectoring operation as well. Examining each of the capabilities separately, thrust vectoring is usually preferable above after burner. However, the priorities can be changed in certain interception conditions. Therefore, implementation of after burner or thrust vectoring capability is recommended conditioned by their detailed analysis as well as pre-known knowledge about the target and interceptor capabilities, optimal evasive maneuvers, and overall playground.