stage separation
Post on 29-Nov-2014
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SPENT STAGE RETARDATION
INTRODUCTION
Stage separation is important in multistage vehicles to drop the burnt out stages from a moving vehicle to improve the performance.
Stage separation failure leads to Mission failure. To avoid this problem separation of burn out or spent
stage has to been done with out any failure. But in stage separation in space removed stage follows
ongoing vehicle with some velocity after the separation due to inertia
STAGING Generally in multi stage vehicles staging is classified in to
two types: Parallel staging. Tandem or serial staging.
In parallel staging both stages fire simultaneously at launch, but the first stage (booster) drops off in mid –flight when spent, while the second stage continues on.
In serial or tandem staging schemes, the first stage is at the bottom and is usually the largest, the second stage and subsequent upper stages are above it, usually decreasing in size. In this one by one get fire after the spent of below stage
PARALLEL STAGING TANDOM STAGING
IMPORTANCE OF STAGE SEPARATION
A multi stage rocket uses two or more stages, each stage fires for a specified period of time and then drops off. This reduces the weight drastically and allows the rocket to reach higher altitudes with low fuel usage.
Multi stage rockets are more efficient than A single stage rocket engines in accelerating the rocket
STAGE SEPARATION
Stage separation program broadly effects on the success of any launch vehicle.
Separation of spent stages as early as possible is a standard practice adopted for improving the performance of multistage launch vehicle.
Stage separation in multi-stage launch vehicles is broadly classified in to 2 types:
I. Stage separation within the atmosphere.
II. Stage separation in space
STAGE SEPARATION
Two possible separation sequences are available for safe separation
Firing of the upper stage motor before the thrust of lower stage motor has decayed
The use of short duration solid propellant rockets to bridge the gap caused by the decay of lower stage thrust
STAGE SEPARATION
STAGE SEPARATION
Some functional requirements essential for separation system in long range missiles
Collision free separation of spent stages Minimum shock transmission to continuing stages Achieve separation in minimum time Mechanism Provides structural rigidity
SEPARATION ELEMENTS
Generally three elements are require to functioning of stage separation process
Actuator - to trigger the event. Release system - for physical separation Jettisoning system - to impart sufficient release
separation velocity to the system
ACTUATOR
actuator is a mechanical device for moving or controlling a mechanism or system.
It takes energy, usually transported by air, electric current, or liquid, and converts that into some kind of motion.
Generally two types of actuators are use in space applications
1. electric based 2. probased
RELASING SYSTEM
Release systems imparts the physical separation to two stages
Various mechanisms can be deployed for stage separation of a large multistage vehicle, and its choice depends on availability of space and requirement of mission.
These systems break the connection between spent stages and moving vehicle with suitable mechanism.
RELASING SYSTEM
Two types of release systems are available i.e.I. Pyrotechnic systems: In pyrotechnic systems Electro explosive devices
(EED) ignite by radio frequency or electric discharge then two stages are separated by releasing the link between them .
Ex: FLSC, explosive bolts, pyrotechnic nuts II. Mechanical systems: Mechanical systems are generally available along with
zip cords and springs these are helps in separation of two stages
Ex: ball and socket, pin pulleys etc
PYROTECHNIC SYSTEMS
EXPLOSIVE BOLTS
PYRO TECHNIC BOLTS1 Light blue First stage 2 Dark blue Second stage P Yellow Piston C Light Green Clamp and extension B Dark Green Pyro body F Grey Fixation wire X Red Pyro charge
PIN PULLEY
JETTISONING SYSTEM
Jettisoning systems are provide the required separation velocity to separating stages.
These systems helps in collision free separation between two stages
These can be active or passive. Passive systems being those which does not require additional systems for jettisoning the spent stages.
Energy required for jettisoning the systems are provided by employing following
Spring thrusters Pneumatic thrusters Rocket thrusters
SPRING THRUSTERS
SEPARATION WITH IN ATMOSPHERE
Generally first stage of launch vehicles are separated with in the atmosphere.
Due to the aero dynamic forces and gravity effect the separation with in the atmosphere don’t cause damage to ongoing vehicle
Spent stages with in the atmosphere easily separated by using suitable release and jettisoning system
STAGE SEPARATION IN SPACE
All stages except first stage are separated in space Stage separation Beyond the atmosphere effected by the
delay between the burnout of lower stage and light up of upper stage. it causes the problem due to absence of aerodynamic forces
Here separation of the two stages is not sufficient because empty shell of lower case follows the upper case
RETRO MOTORS
Retro motors also called as retro rockets and small rocket motors
These are produce the reverse thrust to retard the spent body
The arrangement of retro motors in motor case sweeps equal angles with respect to reference axis
The structural components are
Chamber shield
Propellant grain
Nozzle
RETROMOTOR COMBUSTION CHAMBER
RETROMOTORS
Chamber outer shield is made with HE15 aluminum alloy
Other aluminium alloy useful which are withstands chamber internal pressure forces
Inner surface of the chamber lined with olass-phenolic composite ablative material to with stand thermal protection of motors
RETROMOTORS
The propellant should be high energy type and keep minimum weight and at the same time mechanically strong to with stands pressure loads
The double base propellant has got excellent mechanical properties with very low smoke exhaust.
INGREDIENTS
Nitrocellulose (NC) -51.3 - Binder
Nitroglycerine (NG) -43.0 - Reactive plasticizer
Diethyl phthalate (DEP) -3.0 - Plasticizer
Ethyl centralite (EC) -1.0 - Stabilizer ,oxidant
Candelilla wax - <1 - Lubricant
RETROMOTORS
These motor exhaust nozzle canted(kept at an angle) for convenience of structural arrangement
Retromotor exhaust nozzles are cant angle such that thrust doesn't effect the vehicle
STAGE SEPARAION USING REROMOTOR
All the motors which are placed in the rocket case ignite at one time
These are produce the 06 to 10% of vehicle velocity in opposite direction
After the separation is made by the release system these are retard the spent body to decelerate the velocity of sent stage
RETARDATION OF SPENT STAGE USING RETRO MOTORS
RETROMOTOR DESIGN
Retro motors are designed based on the ongoing vehicle velocity at that stage separation
Material selection depend on the chamber internal pressure forces
Propellant grain and its structures restricted to some types depend on the requirements
CONCLUSION
Stage separation beyond the atmosphere is higher importance
Retarding the spent stage after the separation in space should be done for not disturbing the path of ongoing vehicle
Use of small rocket motors for retarding the spent stage is advantageous than use of spring thrusters
THANK YOU
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