Orbital Minotaur VI - Manual (Page 49)

Minotaur IV • V • VI User’s Guide Section 4.0 – Payload Environment
4. PAYLOAD ENVIRONMENT
CAUTION
The predicted environments provided in this user's guide are for initial planning
purposes only.
Environments presented here bound typical mission parameters, but should not
be used in lieu of mission-specific analyses. Mission-specific levels are provided
as a standard service and documented or referenced in the mission ICD.
This section provides details of the predicted environmental conditions the payload will experience during
Minotaur ground operations, powered flight, and launch system on-orbit operations.
Minotaur ground operations include payload integration and encapsulation within the fairing, subsequent
transportation to the launch site and final vehicle integration activities. Powered flight begins at Stage 1
ignition and ends at final stage burnout. Minotaur on-orbit operations begin after final stage burnout and
end following payload separation. To more accurately define simultaneous loading and environmental
conditions, the powered flight portion of the mission is further subdivided into smaller time segments
bounded by critical, transient flight events such as motor ignition, stage separation, and transonic
crossover.
The environmental design and test criteria presented have been derived using measured data obtained
from many different sources, including Minotaur flights, Peacekeeper motor static fire tests, and other
Orbital system development tests and flights. The predicted levels presented are intended to be
representative of a standard mission and contain margins consistent with MIL-STD 1540B. Satellite mass,
geometry and structural components vary greatly and will result in significant differences from mission to
mission.
Dynamic loading events that occur throughout various portions of the flight include steady-state
acceleration, transient low frequency acceleration, acoustic impingement, random vibration, and
pyrotechnic shock events.
4.1. Steady State and Transient Acceleration Loads
Design limit load factors due to the combined effects of steady state and low frequency transient
accelerations are largely governed by payload characteristics. A mission-specific Coupled Loads Analysis
(CLA) will be performed, with customer provided finite element models of the payload, in order to provide
precise load predictions. Results will be referenced in the mission specific ICD. For preliminary design
purposes, Orbital can provide initial Center-of-Gravity (CG) netloads given a payload’s mass properties,
CG location and bending frequencies.
4.1.1. Transient Loads
Transient events account for approximately 90% of the total space vehicle loads with the remainder due
to steady state events. Transient loads are highly dependent on SV mass, CG, natural frequencies, and
moments of inertia as well as the chosen separation system and Payload Attach Fitting (PAF). All of
these were varied to develop a range of transient lateral accelerations at the typical dominant transient
event and are shown as a function of payload mass in Figure 4.1.1-1 for Minotaur IV and Figure 4.1.1-2
for Minotaur IV+, V, VI, and VI+. These graphs cover a wide range of parameters whereas most
spacecraft/payloads will typically have lateral accelerations below 3.5 G’s.
Preliminary and final CLAs will be performed for each Minotaur mission where the payload finite element
model is coupled to the vehicle model. Forcing functions have been developed for all significant flight
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