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Fig. 5. Graphs of variance of the soil normal reactions on three legs of the spacecraft
in the contact points (
1
,
2
,
3
) on the surface of a celestial body at different forces in
the shock absorber
soil reaction force on the legs is small but the strut inclination angle after
landing is also small (
α
f
= 32
.
3
◦
). This case is unacceptable since a critical
angle of the strut inclination after the spacecraft landing must not exceed
α
fl
= 30
.
0
◦
. Considering force excitations in the shock absorbers in the
third case, the strut inclination angle is lower than the accepted value after
the spacecraft landing. Therefore, for the legs of the given dimensions and
for the given design parameters of the spacecraft, the second case, where
the strut inclination angle after the spacecraft vertical landing is
α
f
= 43
.
4
◦
,
proves to be more acceptable.
We shall estimate different parameters of the spacecraft landing under
the following initial conditions:
y
0
= 1
.
4
m,
V
y
0
= 0
.
1
,
V
x
0
= 0
,
μ
1
=
μ
2
= 0
.
2
,
ϑ
0
= 10
◦
,
θ
g
= 0
◦
. Fig. 6 shows graphs of variance
of the soil normal reactions on the spacecraft legs.
It is clear that at the first moment there is a contact between the second
and the third legs. Then the spacecraft turns around on these legs until the
first leg touches the soil. When the first leg touches the soil, the soil normal
reaction force on the second and the third legs decreases to zero two times.
Fig. 7 contains graphs of variance of the deformation of the shock
absorbers during the spacecraft landing. The graphs of variance show that
Fig. 6. Graphs of variance of the soil normal reaction forces
F
N
1
,
F
N
2
on the first
(
•
) and the second ( ) legs
32 ISSN 0236-3941. HERALD of the BMSTU. Series “Mechanical Engineering”. 2014. No. 1