Studies on Lunar Lander stability behaviour using a 1/6th Scale Model
- Paper number
IAC-20,C2,IP,24,x58266
- Author
Mr. SARATH P MOHAN, India, Team Indus, Axiom Research Labs Pvt. Ltd.
- Year
2020
- Abstract
Safe and stable landing on lunar terrain is a critical design requirement for all Lunar Landers. Design of landing gears of a Lunar Lander is thus a very critical step. The Lander under consideration is equipped with four multi-functional Landing Gears incorporating special energy absorbing devices and foot pads. The safety and stability of the Lander with known mass/inertia properties and velocities (vertical, horizontal, angular) impacting on a terrain with differing properties is critical and must be evaluated and understood. Evaluating stability of the lander descending for different combinations of velocities and angular orientations/rates on different types of terrain under the reduced ‘g’ conditions of moon is indeed very useful for design validation at an early stage. This paper explains the work done in detail on the test setup, lander model and test results. Firstly, a free body drop of a 1/6th scale model on Earth produces dynamically similar effects as a full-scale model on the moon. This is due to similarity of the acceleration due to gravity ratios of both the scenarios. The model studies are done mainly for landing (static and dynamic stability) evaluation and the main parameters considered while scaling the model are the overall geometry of the lander and the CG location. An extremely simple set up of an instrumented pendulum test stand with a special terrain simulator (for ground testing) tray is designed and fabricated to conduct these model tests. The double bar linkage pendulum has an electromagnetically operated hold-and-release mechanism for simulating the specified horizontal touchdown velocities of the lunar lander. The test stand is able to give specified combination of velocities with lander descending in any given orientation. Also, the Lunar regolith in the tray can simulate terrain conditions including slopes and stiffness. This methodology enabled study of the stability of actual lunar soft landing and helped evaluate design parameters affecting impact well in advance. The full paper outlines the detailed experimental results obtained. In addition to the basic results on static and dynamic stability, the experiments were also very useful to study parameters like footpad penetration and sliding for different terrain conditions including slope. Parameters like vertical velocity, horizontal velocity, lander orientation, location of C.G of spacecraft and the geometry of the spacecraft with landing gear along with slope of the regolith play major role in the stability of landing. This paper explains the influence of these parameters also using test results.
- Abstract document
- Manuscript document
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