Start Date
4-1968 8:00 AM
Description
Parachute decelerators used exclusively or in combination with retro rockets have been considered prime candidates for the terminal descent and landing system of a scientifically instrumented Mars lander. The objective of this study is to understand basic relationships between parameters affecting dynamic response of the parachute and capsule and to define those aspects of the system which have a sensitive effect on the design of the lander capsule. Of particular interest is the response of the capsule to wind gusts and to establish the sensitivity to gust onset rates in the VM series of Martian atmospheres.
The model used in studying parachute/capsule relationships consists of two bodies, each with three degrees-of-freedom, connected by an elastic riser cable. The total elastic nature of the parachute and shroud lines is simulated by the equivalent elasticity of the riser cable. The parachute and its enclosed and apparent inertia effects are treated in a rigid body sense. Parachute opening phase dynamics are included in the analysis model.
Motion of the system is examined in either the pitch or yaw plane with roll motion assumed to be controlled near zero by an attitude control system. Capsule attitude excursions and attitude rates are investigated in detail because of their impact on optical and radar sensors. The ability of a simple rate damping attitude control system to combat capsule oscillations is included in the study.
Usually a planetary entry vehicle utilizes a blunt body aeroshell coated with ablative material for the high dynamic pressure, high Mach number portion of the entry trajectory. Once this region has been traversed and Mach number is reduced to approximately 1.6, the parachute decelerator may be deployed. From this point on, the aeroshell serves little usefulness and may complicate the touchdown mechanics. It may be desirable, therefore to jettison the aeroshell as soon as possible after parachute deployment. The ease of accomplishing aeroshell separation while descending on a parachute is evaluated.
Mars Lander Vehicle/Parachute Dynamics
Parachute decelerators used exclusively or in combination with retro rockets have been considered prime candidates for the terminal descent and landing system of a scientifically instrumented Mars lander. The objective of this study is to understand basic relationships between parameters affecting dynamic response of the parachute and capsule and to define those aspects of the system which have a sensitive effect on the design of the lander capsule. Of particular interest is the response of the capsule to wind gusts and to establish the sensitivity to gust onset rates in the VM series of Martian atmospheres.
The model used in studying parachute/capsule relationships consists of two bodies, each with three degrees-of-freedom, connected by an elastic riser cable. The total elastic nature of the parachute and shroud lines is simulated by the equivalent elasticity of the riser cable. The parachute and its enclosed and apparent inertia effects are treated in a rigid body sense. Parachute opening phase dynamics are included in the analysis model.
Motion of the system is examined in either the pitch or yaw plane with roll motion assumed to be controlled near zero by an attitude control system. Capsule attitude excursions and attitude rates are investigated in detail because of their impact on optical and radar sensors. The ability of a simple rate damping attitude control system to combat capsule oscillations is included in the study.
Usually a planetary entry vehicle utilizes a blunt body aeroshell coated with ablative material for the high dynamic pressure, high Mach number portion of the entry trajectory. Once this region has been traversed and Mach number is reduced to approximately 1.6, the parachute decelerator may be deployed. From this point on, the aeroshell serves little usefulness and may complicate the touchdown mechanics. It may be desirable, therefore to jettison the aeroshell as soon as possible after parachute deployment. The ease of accomplishing aeroshell separation while descending on a parachute is evaluated.
Comments
No other information or file available for this session.