Exploring the Unknown: Selected Documents in ... - The Black Vault

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Project Apollo: Americans to the Moon
on a performance basis, since it is possible from a weight standpoint to convert from
storables to cryogenics at a later date, but the reverse is not true. Only LOR or 2-man
EOR are compatible with the choice of storables in all space stages.
Weight Margin. The establishment of a proper weight margin is a factor
in the realizability of the C-5 direct modes. Our experience has shown that weight
levels for manned space vehicles have grown approximately 25% over initial “hard”
estimates. This growth accommodates initial misestimates of hardware weights,
equipment additions to increase mission capability, and design changes required
by better definition of the environment. As a result of their studies, both Space
Technology Laboratories and McDonnell Aircraft Corporation concluded that a
l0% weight margin would be adequate to cover initial weight misestimations. Our
experience dictates that an additional 15% be included for both increased mission
capability and design changes which might result from increased environ mental
knowledge. The requirement for this increased weight margin does affect the
possibility of using a storable return propulsion system for the 2-man C-5 direct
mission. Considering all factors, the use of storable return propulsion would not
provide sufficient assurance of success for the 2-man C-5 direct mode.
Lunar Landing Configuration. There are important differences in landing
configuration between the Lunar Excursion Module (LEM) and the Command
Module (CM). Although the landing can be achieved with either module, the
LEM can be “optimized” for the lunar operations more readily than the CM which
must also accommodate re entry. The main factors are the internal arrangement of
the capsules, and the degree of visibility provided the astronauts during the lunar
landing phase. Landing the CM (particularly the 2-man version) would undoubtedly
require use of television cameras to augment the pilot’s field of view.
[4] In comparing the modes in the vicinity of the moon, both the C-5 direct
and the EOR flight configurations must be staged during the terminal descent
phase to reduce engine throttling requirements and landing gear loads. This
staging requirement and the less desirable module arrangement are the factors
in the direct landing mode which must be weighed against the requirement for
rendezvous in the LOR mode. Continued study of alternate configurations has
indicated that the simplicity of the LOR landing configuration is most desirable
for early mission success.
In LOR, the re-entry and flight capsule can be separated from the lunar
landing capsule during the course of the development program. Re-entry and
flight requirements will affect the mass and moment of inertia of the re-entry and
flight capsule, as well as the internal couch arrangement and the pilot displays.
Astronaut position during lunar landing will affect the internal arrangement of
the lunar landing capsule, and the visibility requirements can profoundly affect
both capsule shape and structural integrity.
The industrial firms bidding on the LEM concluded that this separation
of function was highly advantageous. (Their comments are summarized in
Appendix C.)