Mission Configuration – Large Payload – Lunar Descent
Section A-7.4.1
A-7.4.1 Structures
Structure
Our calculations of the frame mass for the Lunar Lander with a large payload scale from
the frame dimensions of the 100g payload Lunar Lander. The Lunar Lander for the 100g
payload does not have the additional engines required to do a hop like the Lunar Lander
for the 10kg payload. The extra two hopper engines have long chambers which cause the
height of the Lunar Lander to increase. A larger increase in height is unnecessary for the
Lunar Lander with the large payload.
Lander_Frame_hover.m calculates the total mass of the Lunar Lander frame for the
large payload case. The process of calculating this mass remains the exact same as the
process used in Lander_Frame_ball.m and Lander_Frame_hop.m for the 100g
payload Lunar Lander and 10kg payload Lunar Lander. Our methods for calculation are
identical to those described in Section A-5.4.1. Lander_Frame_hover.m differs in that
scaling factors are used from the original frame mass calculation. The dimensions and
shape of the Lunar Lander are illustrated in Figure A-7.4.1-1.
Figure A-7.4.1-1. Basic frame shape and dimensions.
Sketch is not to scale. (Ryan Nelson)
The basic frame design for the 10kg and 100g payload Lunar Landers is not practical for
this large payload Lunar Lander. The size and mass of the four rectangular floor supports
Author: Ryan Nelson
Mission Configuration – Large Payload – Lunar Descent
Section A-7.4.1
must be extremely large to support the bending moments at lunar touchdown. With the
previous frame design and analysis discussed in Section 5.4.1 and Section 6.4.1 the
length of these rectangular floor supports is small enough to handle the smaller bending
moments subjected to these frames. Since the outer ring on the Lunar Lander floor frame
scales up to the maximum diameter of the Falcon 9 fairing, each of these rectangular
floor supports becomes 1.385 meters long.
Equation 1 in Section A-5.4.1 shows that as the length of the rectangular beam supports
increases, the bending moments increase linearly. However, as the bending moments
increase, the thickness and mass of the rectangular floor supports increases exponentially.
The increase in bending moments prove that this simple design used in Section 5.4.1 and
Section 6.4.1 is not sufficient for a larger Lunar Lander. For this reason a frame scale
from the 100g Lunar Lander frame gives more accurate results. The scale up results in a
calculated Lunar Lander mass of 104.86 kg for the large payload case.
Lander_Frame_hover.m involves the calculation of each frame component with the
given large mass at lunar touchdown which is 2802 kg. However, the same dimensions
for100g payload Lunar Lander found in Section 5.4.1 are used rather than the dimension
of the large payload Lunar Lander frame. Once calculation for the mass of each frame
component using the 100g payload Lunar Lander dimensions occurs, the scale factors are
implemented. The rectangular floor supports, engine support ring, and outer floor ring
multiply by a factor of 2.77. The side supports and legs are multiplied by a factor of 2
and the top ring of the Lunar Lander frame and legs are multiplied by a factor of 2.4.
Various parts of the Lunar Lander frame are scaled differently to get the best fit for all of
the Lunar Lander subcomponents such as the main engine, H202 tank, payload, pressure
tank and other components.
The angle at which the legs are oriented modifies for this large payload Lunar Lander
frame. Since different parts of the Lunar Lander are scaled differently from the 100g
payload Lunar Lander frame, the angle of the legs is oriented at 16.7°. The thickness of
Author: Ryan Nelson
Mission Configuration – Large Payload – Lunar Descent
Section A-7.4.1
the legs is a function of the angle of orientation. A larger angle results in larger buckling
loads which the legs must withstand. The legs account for a larger portion of the overall
frame mass than with the 100g payload frame. Rectangular floor support beams still
account for the largest portion of frame mass.
Author: Ryan Nelson