11.5 Design of Landing Gear Mechanism
383
Fig. 11.11 Connection of
parts. 1-Primary strut;
2-Secondary strut;
3-Footpad; 4-Ball joint II;
5-Universal joint I; 6-Ball
joint I; 7-Universall joint II
where: n is quantity of the landing gear mechanisms.
2. Design of Landing Gear Mechanism
1) Subsystem design of landing gear
(1) Joint design. As sown in Fig. 11.11, the primary strut was attached at the
upper end to main structure of the lunar lander by a universal joint I, while
at the lower end to a footpad by a ball joint I. One end of each secondary
strut was connected to primary strut through a ball joint II, while the other
end was connected to main structure through a universal joint II.
(2) Strut design. Every strut absorbed impact energy by cushion material
inside. The primary strut generally absorbed vertical impact load while
secondary strut absorbed horizontal impact load. The primary strut could
only be compressed while secondary strut could be both compressed and
stretched.
(3) Design of hold down, release, deploy and lock up mechanism. The primary
strut could be held down by additional joint between the primary strut
and the structure, or compression of the secondary strut. The deployment
spring and lock up mechanism at the joint connecting strut with the structure or inside the secondary strut were designed for deployment and lock
up. The minimum static torque (force) margin of the mechanism should
be not less than 1. In order to reduce locking impact load, a damping cell
was usually included.
(4) Support and anti-subsidence design. The footpad with a larger base area
could effectively support the lunar lander and prevent it from subsidence
on soft-landing surface. In conditions with larger horizontal velocity, the
lunar lander with footpad could smoothly slide on landing surface so as
to improve landing stability.
(5) Design of lunar surface sensing probe. The lunar surface sensing probe
was designed to output signal at touchdown, which might be a probe
beneath the footpad or triggering switch on the bottom surface of the
footpad.
2) Design of primary strut.
383
Fig. 11.11 Connection of
parts. 1-Primary strut;
2-Secondary strut;
3-Footpad; 4-Ball joint II;
5-Universal joint I; 6-Ball
joint I; 7-Universall joint II
where: n is quantity of the landing gear mechanisms.
2. Design of Landing Gear Mechanism
1) Subsystem design of landing gear
(1) Joint design. As sown in Fig. 11.11, the primary strut was attached at the
upper end to main structure of the lunar lander by a universal joint I, while
at the lower end to a footpad by a ball joint I. One end of each secondary
strut was connected to primary strut through a ball joint II, while the other
end was connected to main structure through a universal joint II.
(2) Strut design. Every strut absorbed impact energy by cushion material
inside. The primary strut generally absorbed vertical impact load while
secondary strut absorbed horizontal impact load. The primary strut could
only be compressed while secondary strut could be both compressed and
stretched.
(3) Design of hold down, release, deploy and lock up mechanism. The primary
strut could be held down by additional joint between the primary strut
and the structure, or compression of the secondary strut. The deployment
spring and lock up mechanism at the joint connecting strut with the structure or inside the secondary strut were designed for deployment and lock
up. The minimum static torque (force) margin of the mechanism should
be not less than 1. In order to reduce locking impact load, a damping cell
was usually included.
(4) Support and anti-subsidence design. The footpad with a larger base area
could effectively support the lunar lander and prevent it from subsidence
on soft-landing surface. In conditions with larger horizontal velocity, the
lunar lander with footpad could smoothly slide on landing surface so as
to improve landing stability.
(5) Design of lunar surface sensing probe. The lunar surface sensing probe
was designed to output signal at touchdown, which might be a probe
beneath the footpad or triggering switch on the bottom surface of the
footpad.
2) Design of primary strut.