M.Sc Thesis

M.Sc StudentAvichai Socher
SubjectA Parametric Investigation of Propulsion Systems for Air
Launch of Micro-Satellites from a Combat Aircraft
DepartmentDepartment of Aerospace Engineering
Supervisor Professor Emeritus Gany Alon
Full Thesis text - in Hebrew Full thesis text - Hebrew Version


Commonly, satellites are launched from the ground by very large, multi-stage rocket launchers. Launching satellites from aircraft can substantially reduce the launcher size and mass. It can also provides low cost and short-notice launch capabilities for tactical applications, replacement of non-functioning satellites, providing fuel for life extension of existing satellite in orbit, and more. This research studies the subject of air-launch of micro-satellites from a combat aircraft, specifically air-launch from an F15 aircraft into a 250 km circular orbit, or a more elliptic one. The following three concepts and configurations were analyzed, coping with the limitations imposed by the carrier aircraft. A gravity turn trajectory was chosen for minimizing structural mass of the launcher:

  • GTLV (Gravity Turn Launch Vehicle) - consists from three solid rocket motors (totaling 3.9 ton), and can launch a 48 kg satellite to a 250 km LEO.
  • DRLV (Ducted Rocket Launch Vehicle) - consists from 1st stage ducted rocket (ramjet) and two solid rocket motors (totaling 3.2 ton), can place a 75 kg satellite in LEO.
  • TRIPOD - a three body configuration (5.7 ton), employing five solid rocket motors in three stages, can place a 114 kg microsatellite in LEO.

The launch sequence and all the parameters were modeled in MATLAB, and a thorough parametric investigation was conducted. A spherical rotating earth model was used in the equations of motion that were written for a planar flight above the equator.

Sensitivity analysis was done on all parameters, to determine the influence of small changes in one parameter on the others, and on the launch results. All calculated results were optimized by total energy at burnout of the 3rd stage.

The results show that there is a sound basis for developing a micro satellite launcher for air-launch from an F15 combat aircraft. Payload capability can be improved in a phased process starting with a standard GTLV configuration, through the use of air-breathing (ramjet) ducted rocket motor and culminating with a unique three-body launcher. The payload improvement is substantial.

The use of an F15 as a platform for launching a tactical microsatellite via three conceptual launchers has been demonstrated. The concepts proved to be viable, and the use of COTS motors decreases costs and development complexity and relieves carrier aircraft constraints in terms of structural modification and flight envelope.