Structural Loads for Crew Escape System of Human Space Flight during Abort VSSC, Indian Space Research Organization

Format:

Book

Conference/Event

Author/Creator:

S, Subash, author.

Contributor:

Babu P, Girish

Daniel, Sajan

Conference Name:

AeroCON 2024 (2024-06-06 : Bangalore, India)

Language:

English

Physical Description:

1 online resource cm

Place of Publication:

Warrendale, PA SAE International 2024

Summary:

In any human space flight program, safety of the crew is of utmost priority. In case of exigency in atmospheric flight, the crew is safely and quickly rescued from the launch vehicle using Crew Escape System (CES). CES is a critical part of the Human Space Flight which carries the crew module away from the ascending launch vehicle by firing its rocket motors (Pitch Motor (PM), Low altitude Escape Motor (LEM) and High altitude Escape Motor (HEM)). The structural loads experienced by the CES during the mission abort are severe as the propulsive, aerodynamic and inertial forces on the vehicle are significantly high. Since the mission abort can occur at anytime during the ascent phase of the launch vehicle, trajectory profiles are generated for abort at every one second interval of ascent flight period considering several combinations of dispersions on various propulsive parameters of abort motors and aero parameters. Depending on the time of abort, the ignition delay of PM, LEM and HEM are adjusted in order to minimize the lateral acceleration on the vehicle, at the same time meeting the horizontal range requirement. Aerodynamic load distributions on the vehicle and aero forces and moments on the Grid fin are generated for various Mach No., Angle of Attack (AoA) combinations for jet ON and jet OFF conditions of PM, LEM and HEM. In order to estimate the structural loads for CES during abort, inertia relief analyses are carried out for static load on a free-free finite element model at all the time instances in the abort trajectory as a time sweep simulation considering the appropriate aerodynamic forces, propulsive parameters (mass consumption and thrust) and trajectory parameters (Mach No., Dynamic Pressure and AoA) at each time instant in the trajectory. During abort at lower altitude along with LEM, Pitch Motor (PM) is fired perpendicular to the axis of the vehicle to turn the vehicle towards the sea thereby increasing the AoA and bending moment on the vehicle. The Pitch Motor thrust acting perpendicular to the vehicle excites the first bending mode and augments the Bending Moment. LEM thrust and HEM thrust acting along the vehicle axis also can excite the axial modes of the vehicle. Similarly the lateral aero dynamic forces on the vehicle excite the lateral dynamics of the vehicle whenever there is a sudden change in the AoA due to wind gust. To account for the flexible body dynamic forces, a load augmentation factor called Flexibility Factor is multiplied on the static loads to arrive at the limiting loads on the vehicle. This paper briefly explains the structural load estimation methodology for CES abort, various inputs required and different steps involved in it

Notes:

Vendor supplied data

Publisher Number:

2024-26-0453

Access Restriction:

Restricted for use by site license