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11 Landing Gear Technology of Lunar Lander
of the lunar lander by universal joint, and the lower end was connected to the footpad
by ball joint, while the middle was connected with two secondary struts by spherical
hinge. Moreover, the other end of each secondary strut was also connected to the main
structure of the lunar lander by universal joint. The cushion cells inside the primary
and secondary struts could absorb the landing impact energy. Most of vertical impact
was absorbed by the primary strut, while most of horizontal impact was absorbed by
the secondary struts. The primary strut could only be compressed and two secondary
struts could be compressed and tensioned. The footpad was applied to adapt to
diverse landing surface and avoid excessive penetration into lunar regolith, which
was also benefit to horizontal slide for the lunar lander at large horizontal velocity to
improve landing stability. The landing gears were held by the Hold Down and Release
Assembly during launch. When the lunar lander was injected into predefined orbit,
the landing gears were deployed and locked up. The landing gear was a kind of
typical spatial multiple DOF mechanism during the landing process and it could also
be taken as a special parallel mechanism.
11.4 Common Cushion Methods and Their Features
Up to date, there were a lot of methods for cushion. But only few of them are
suitable to landing cushion mechanism for space application, such as cellular material
deformation, plastic deformation of a thin-walled metal tube, hydraulic damping and
tensile deformation of the special material, etc.
11.4.1 Cellular Material Deformation
Aluminum honeycomb and aluminum foam were two kinds of typical cellular material. Because of high porosity, high specific strength, high specific modulus, excellent
heat resistance and corrosion resistance, they were usually used as shock cushion
material of irreversible deformation.
1. Aluminum Honeycomb
The mass density of aluminum honeycomb is lower, while its compression ratio
(ratio of compressible length to initial length) is higher with reasonable compression
strength and specific energy absorption up to 30 kJ/kg. Compared to fluid or gas
filled damper, the advantages of aluminum honeycomb are steady damping force, low
mass density, insensitive to space environment. Furthermore, according to different
impact load input during landing process, several chained aluminum honeycomb
blocks with different compression strength can be applied to ensure the stability of
impact response.
The correlation between load and deformation of aluminum honeycomb could be
acquired through static compression test and dynamic impact test. In application or
11 Landing Gear Technology of Lunar Lander
of the lunar lander by universal joint, and the lower end was connected to the footpad
by ball joint, while the middle was connected with two secondary struts by spherical
hinge. Moreover, the other end of each secondary strut was also connected to the main
structure of the lunar lander by universal joint. The cushion cells inside the primary
and secondary struts could absorb the landing impact energy. Most of vertical impact
was absorbed by the primary strut, while most of horizontal impact was absorbed by
the secondary struts. The primary strut could only be compressed and two secondary
struts could be compressed and tensioned. The footpad was applied to adapt to
diverse landing surface and avoid excessive penetration into lunar regolith, which
was also benefit to horizontal slide for the lunar lander at large horizontal velocity to
improve landing stability. The landing gears were held by the Hold Down and Release
Assembly during launch. When the lunar lander was injected into predefined orbit,
the landing gears were deployed and locked up. The landing gear was a kind of
typical spatial multiple DOF mechanism during the landing process and it could also
be taken as a special parallel mechanism.
11.4 Common Cushion Methods and Their Features
Up to date, there were a lot of methods for cushion. But only few of them are
suitable to landing cushion mechanism for space application, such as cellular material
deformation, plastic deformation of a thin-walled metal tube, hydraulic damping and
tensile deformation of the special material, etc.
11.4.1 Cellular Material Deformation
Aluminum honeycomb and aluminum foam were two kinds of typical cellular material. Because of high porosity, high specific strength, high specific modulus, excellent
heat resistance and corrosion resistance, they were usually used as shock cushion
material of irreversible deformation.
1. Aluminum Honeycomb
The mass density of aluminum honeycomb is lower, while its compression ratio
(ratio of compressible length to initial length) is higher with reasonable compression
strength and specific energy absorption up to 30 kJ/kg. Compared to fluid or gas
filled damper, the advantages of aluminum honeycomb are steady damping force, low
mass density, insensitive to space environment. Furthermore, according to different
impact load input during landing process, several chained aluminum honeycomb
blocks with different compression strength can be applied to ensure the stability of
impact response.
The correlation between load and deformation of aluminum honeycomb could be
acquired through static compression test and dynamic impact test. In application or