Vibration – Sine, Random & Shock
Vibration test specifications are determined by the type of motor used for launching the payload. Payload reactions depend on the size, weight and weight distribution (harmonic frequencies) of the payload. Vibration transmission problems can create excessive motion of sensitive electronic parts. Components are, therefore, vulnerable to failure from vibration and must be rigidly attached to prevent abrasion and subsequent shorting. Sounding rocket payloads are calibrated based on existing component qualification specifications for the 10 rockets in the NSROC Stable and for the newly designed payloads. The vibration test simulates the sound and shock which the payload will experience during various phases of motor burn and measures its ability to withstand that shock in order to complete a successful launch.

Balance: Static & Dynamic
Sounding rockets are made to spin during powered flight to aid in stability. Therefore, all payloads must be balanced, statically and dynamically. These tests are very similar to the tests performed by mechanics in order to determine whether or not the tires on your car are balanced. In both cases, correction weights are installed to adjust and balance the payload.

Operational Spin & Deployment Testing
All mechanically operated or deployed parts (nose cones, instruments, antennas, doors, booms) must be tested to ensure that they will perform successfully in flight. The spin of a rocket normally increases during assent. The rate of that spin is determined by the size and power of the rocket motor and the angle of the fins. To test the ability of a sounding rocket to withstand the impact of the spin at and after deployment, the nose cones, instruments, antennas, doors and booms are tested with machinery that duplicates the spin environment. Telemetry signals, sent to the ground station during the test, indicate the part's ability to withstand the centrifugal force applied. Click here to see the Boom Deployment Testing of the Fiberglass Boom Mount which was demonstrated on the Mechanical Engineering and Drafting Links.

Mass Properties
The payload's mass properties (weight, center of gravity, moments of inertia) are determined by test or calculation. Final measured properties are always determined during payload test and evaluation. Requirements for moments of inertia are necessary to determine suitability of the trajectory, predict Attitude Control System performance and to calculate stability.

Vacuum & Thermal Vacuum Testing

Thermal Testing:
Sounding rocket launch vehicles reach very high speeds traveling through the earth's atmosphere. Surface heating at hypersonic speeds is significant due to the friction encountered flying through the air mass. Atmospheric heating is encountered when a payload re-enters the atmosphere from space. Even though the payload's exterior skin surfaces experience relatively high temperature rises due to ascent aerodynamic heating, the temperature of internal components does not vary greatly over the course of a typical flight. This factor depends primarily on where and how components are mounted relative to the payload skin. Thermal testing determines a component's sensitivity to elevated temperatures and, relatedly, the need to insulate or isolate it from projected heat sources

Vacuum Testing:
When rocket payloads rapidly ascend in the atmosphere during launch, ambient atmospheric pressure drops quickly to essentially zero. Payloads are generally designed to vent internal air. Barometric switches are often utilized for switching functions in payload electrical subsystems. Some types of payload components may not tolerate low atmospheric pressures.

The two most common undesirable effects of vacuum are reduced heat transmission and corona. Both can be easily addressed when identified by vacuum testing. In many cases, some portions of payloads require hermetically sealed joints or doors to maintain sealed conditions either under pressure or vacuum.

Out-gassing:
When out-gassing can degrade the performance of an experiment, a thermal vacuum test is required to verify the absence of contaminants. The test may be performed in several parts; the nose cone, for example, may require a higher temperature for a longer period than the PI's equipment can tolerate. The test must conclusively show that contamination will not impair the data to be gathered during flight.