A.2.2.3 Range Safetypg. 1

A.2.2.3 Range Safetypg. 1

Range Safety:

Introduction

The range safety subsystem in our launch vehicle exists to ensure public safety during the launch and flight of our rocket. Public safety is defined as preventing damage or harm to people or property. If the rocket behaves erratically, fails to remain inwithin its flight corridor, or malfunctions in a way which prevents it from reaching orbit, then the range safety system can be used to recall the rocket to Earth.

Launch Corridor

To maintain public safety, the launch vehicle will fly within aflight corridor. The flight corridorexists in a space above the launch range. If the launch vehicle loses power during flight, the vehicle will fall to the ground in an uninhabited area. An engine failure outside the flight corridor means it may fall on people or property. Therefore if the launch vehicle exits the flight corridor, the Range Safety Officermust destroy the launch vehicle to ensure public safety. Destruction of the launch vehiclewill be done remotely using explosive charges, due to their high reliability.

Range Safety Officer

The term Range Safety Officer, or RSO, describes an individual who is responsible for the remote destruction and consequent flight termination of the launch vehicle should it be deemed a hazard. To assure public safety, the RSO and the personnel working under him mayevaluate the launch vehicle’s design as well as overview its manufacture and assembly. The RSO monitors both the launch vehicle and environmental conditions prior to launch for anything that may necessitate the postponement of the launch.Finally the RSO monitors and tracks the launch vehicle during flight.The RSO’sjob duration ends when either the launch vehicle is destroyed or reaches orbit. In our case we prefer the latter and define orbit as an altitude of 300km described in the mission statement.

Destruction Methods

The manner in which the launch vehicle is destroyed is highlycircumstantial. In most cases it is common to first terminate the launch vehicle’s propulsionsystem prior to destruction.Afterwards two real options are available. The first option is to detonate the explosive charges aboard the launch vehicle while it is still in flight. Detonating the charges allow the debris to dissociate through the air lessening the force of impact. The secondoption is to leave thelaunch vehicleintact. Not detonating the chargesallow for a localizeddebris field. Choosing either option is the responsibility of the RSO and dependsmainly on the current situation.In a study presented from the book “Streamlining Space Launch Range Safety”, it was shown that the malfunctioning rocket was first destroyed from dynamic forces before ground personnel reacted.

Automated Vehicle Termination

Flight tracking of the launch vehicle is also monitored internally and flight termination may be initiated automatically without input from the RSO.The avionics of the launch vehiclewill perform this task.The avionics will do thisby using sensor data that pertains to positioning, such as the IMU. The data is used by the flight computer to determine the vehicles current position in relation to its intended flight path. If the computer determines that it is outside its designated flight corridor, then the computer will initiate termination itself. Automated termination is used as a compliment to the RSO and is not intended to replace him/her.

Range Safety Considerations

The Federal Aviation Regulations, or FARs, require the launch vehicle have at least two adequate and independent components relaying tracking information from the vehicle to the ground. According to the FARs, it is acceptable to lose one of the two components needed for tracking.However ifboth componentsare lost, it is immediate cause to terminate the launch vehicle.The launch vehicle must be destroyed even if there is no indication that it is straying from the intended flight path.The launch vehicleis destroyed in this situation to ensure public safety. So it is understood that requiring two components is more a form of redundancy to ensure public safety and mission success rather than functionality. This lesson is used as a guideline to design a complete subsystem.

Existing Range Safety Subsystem

It was found through research that companies such as Honeywell and L3 Communications manufacture and sell complete range safety packages. Honeywell has a system calledBallistic MissileRange Safety Technology. They claimtheir systemhas everything required for a total mobile range safety solution. Likewise L3 has their version of a range safety system. However, Honeywell’s and L3’s packages are considered toocomplicated and out of scope of thisclass.Also the costs of Honeywell’s and L3’s systems significantly over expanded the design budget.

Our Range Safety Subsystem

Many components from the existing avionics packagewill be used to create a complete range safety subsystem.Using the existing components will save on complexity, weight, and cost. The avionics flight computer is incorporated into the design and used to perform the task of autonomous vehicle termination. The subsystem will also use the existing IMU, and sensor package. The IMU is needed to relay the tracking data to the flight computer so it can perform its assigned task. The existing sensor packageisneeded to relay vehicle health data back to the RSO which will aid in his task.

The range safety subsystem also requires components not in the existing avionics package.The new components include a transmitter, receiver, antenna, global positioning unit, explosive charges, and associated safe/arm devices.

A separate transmitter and receiver can be combined into one unit called a transceiver. The transceiver and antenna will be used as a dedicated relay for the destruct signal.It is also a good idea for the transceiver tohave encryption on it. The encryption will protect the launch vehicle from anyone besides the RSOfrom uploadingthe destruct command. Aerocomm has one such transceiver that will be adequate forus. The transceiver from Aerocomm operates on an S-band frequency, so the chosen antenna must also match this operating frequency in order to function.Using the antenna from Syntronicswill be adequate for us. Finally the global positioning unit, or GPS, will act as a second redundant unit working beside the IMU. A schematic of what a complete system looks like is shown in Fig.

Range Safety “Black Box”

The explosives and associated safe/arm devices had to be place into the avionics black box. This was done because no research material was foundon the subject matter and thus an analysis could not be performed. It should also be noted that a complete range safety system from top to bottom is largely unknown. Everything that has not been discussed in this appendix pertaining to a complete range safety system has been placed in this black box.

Author: Timothy Lorenzana