The Space Environment Dynamometer Test Bed is designed to support a wide range of test article configurations by providing a flexible interface for physical, electrical, and control integration within a thermal vacuum environment. Housed in a modular 304 stainless steel chamber with a maximum internal length of 114 cm and diameter of 40 cm, it supports cold testing via a Cryomech AL325 cryocooler connected to thermal straps. Interface flanges with thermal standoffs are recommended for test article mounting, and several ISO-KF ports allow for instrumentation and sight glass access. Vacuum is maintained by a scroll pump (7×10⁻³ torr) or optionally by a turbo pump (5×10⁻⁶ torr). Input and braking loads are applied using a range of motors and pneumatic brakes, with torque measured by Interface static torque sensors and speed measured via resolvers or Renishaw absolute encoders. Rotary feedthroughs, linear rails for axial alignment, and configurable power supplies (up to 5000 W) support diverse test scenarios. Data acquisition is managed via a National Instruments cRIO system, capable of synchronizing multiple parameters into a single TDMS data file, with options for expanded I/O and real-time control customization by the Kennedy Space Center test team.

The Test Bed was initially designed for a test article with an integrated motor, hence a motor is not included with the Test Bed. However, a motor can be added with modifications.

Criteria	Quick Reference Value
Test Article Diameter Limit (cold testing )	17.2 cm
Test Article Diameter Limit (room temperature testing)	37.5 cm
Test Article Length Limit	87.6 cm
Achievable Vacuum	10-4 torr standard (10-6 torr optional)
Achievable Cold Environment	140 W @ 30 K
Output Braking Capability	960 Nm @ 500 rpm (upper range) 1.5 Nm @ 2500 rpm (lower range)
Feedthrough Limiting Speed	1640 rpm
Test Article Power Draw Limit	480 W (24 VDC @ 20 Amps)
Available Temperature Probes	23
Maximum Test Duration	100 days (continuous operation).

Thermal Vacuum Chamber

The test chamber area is made of 304 stainless steel, and is 40 cm in internal diameter. The modular design of the chamber allows for use of just one or two of the three available cylindrical chamber sections, or for additional sections to be installed to increase the total available internal length of 114 cm. If cold testing is required, all three sections must be used to accommodate the large Cold Finger Strap Mount Block (See Figure 2), unless a smaller Block is fabricated. In general, for cold vacuum testing, a maximum test article diameter of approximately 17.2 cm is recommended to allow for appropriate thermal strap placement.

Test Article Mounting Interface Plates

To limit thermal loses, it is recommended that all test articles be mounted on interface flanges with thermal standoff spacers. To mount the test article to the chamber, an adapter can be fabricated to interface with the bolt hole pattern on the pedestal mounted in the chamber interior (see Figure 3). This bolt hole pattern is shown below. This adapter should be of the correct length to position the test article in the center axis of the chamber for output shaft alignment. This adapter should also be designed to position the test article in the middle of the chamber, which is especially important for cold testing. When not cold testing, the pedestal can be mounted on any of the three chamber sections. The KSC test team is available to help design the adapter mount hardware.

Chamber Access Ports

Several ISO-KF style ports are available for interfacing with the test article. Optionally, additional sight glass windows may be installed on an available port if desired. Additional chamber sections may also be installed. If needed, KF Flange Tee’s may be used to increase the total amount of instrumentation pass through. These ports are detailed below.

Vacuum System

The Test Chamber is typically evacuated by an Agilent/Varian Triscroll PTS06001UVPI 500 lpm scroll pump capable of achieving 7×10^-3 torr ultimate vacuum. When needed, a turbo molecular pump can be added (depending on availability) to achieve a 5×10^-6 torr ultimate vacuum. If the user has detailed information available for their test article, final vacuum levels may be estimated from the following pumping curve for the standard scroll pump only configuration.

Cryo Pump and Chiller

Cold testing is achieved by the use of a cyrocooler. A Cryomech AL325 Gifford-Mcmahom cryocooler with a cooling capacity of 100W @ 25K is coupled to the braided copper straps to remove heat from the test article. Below is detailed information on the AL325 cryocooler.

External Load System

Input Motor Loads– Typical testing to date has only consisted of testing articles with integrated motors. However, input rotational loads from a motor external to the chamber is available for passive test articles such as gear boxes. The KSC Test Team has a wide variety of motors available for use, including open loop and close loop control schemes depending on customer requirements.

Braking Loads– Braking Loads for powered test articles are provided by Re pneumatic brakes. The load from the brake is closed loop controlled from the output torque sensor to provide a much smaller variance in load input. The brake consists of 6 calipers, each capable of providing minimum of 1.5 N-m at 0.3 bar and maximum of 160 N-m at 6 bar, a total of 960 N-m maximum when all calipers are used. Other loads outside of this may be accommodated.

Torque Measurement– Loads are measured from reactionary (static) torque sensors from Interface Force Measurement Solutions. Reactionary torque sensors can be used on the input and the output when possible to measure efficiency of the test article.

Speed Measurement– Typical testing to date has only consisted of testing articles with integrated resolvers. RPM telemetry had been captured by use of those resolvers. However, an incremental encoder on an input drive motor (if used) may be used. A Renishaw absolute encoder with 26-bit resolution can also be attached to the input and/or the output of the test article to record position and velocity. These can be located inside the vacuum chamber.

Vacuum Rotary Feedthrough

Feedthroughs for rotary motion out of the chamber use FerroTec vacuum rotary feedthroughs.

Linear Rail Alignment System

The chamber and all attachments are located on linear profile rails. These rails provide an easy method to assemble the test articles and other items while maintaining critical axial alignment between all rotary components.

Power

A variety of power service is available to test articles including:

• Multi-range 1200 W, 80 VDC at 60 amps
• Multi-range 5000 W, 250 VDC at 80 amps

Customers may also provide their own power equipment as needed. If customer provided power is provided, procurement of the proper vacuum rated electrical feedthrough may also be required.

Data Acquisition and Control Components

Experimental command, data acquisition, and control is achieved via a National Instruments (NI) cRIO based real time industrial controller. 25 temperature measurements are available and are recorded to the data log along with pressure, torque, and speed. The power draw of various components can also be recorded to calculate efficiencies.

Test Bed control system can be readily expanded to meet customer needs for additional Input and Output types. This is beneficial when synchronization of the control and response data streams is desired as all system parameters can be recorded into a single timestamped data file. The KSC test team is available to discuss software and control hardware modifications needed to accommodate different test articles.

Data Package Format

Data from the test will be made available in TDMS format. This is a compact binary data storage format native to the National Instruments Data Acquisition system. A free TDMS to Excel converter is available from National Instruments if needed.