ai-aerospace/ams_data_full_2000-2020 huggingface dataset:
342  

Figure 11: Results of ring profile revision on sub-24” predicted system stiffness  To maximize the load capability of the system (beyond the ESPA Grande requirements), the high-load  CBOD (13,500 lb / 60 kN) was incorporated. Band thickness was increased to handle the larger CBOD loads, and it was found that the band stress associated with deforming the band from its free-state to the installed diameter was higher than expected, severely limiting the gains of a thicker band. The thickness of the aluminum was adjusted to maintain similar installed force with previous designs. To improve margin on gapping load, the ring half-angle was reduced to 15° from the 20° baseline.   The final band design (Aluminum 7075-T7351) uses a nominal 9200-lb (41-kN) band preload (10,000-lb  (44-kN) proof load), with a yield stress margin of 0.05 and an ultimate stress margin of 0.22 (with SFy = 1.1 and SFu = 1.4, and a preload uncertainty factor of 1.1). The predicted stiffness and load capability for this size system is excellent even though only 75% of the CBOD load capability is used. The 9200-lb (41-kN) nominal band load in the sub-24 LPSS allows the CBOD to show >100% margin.  Analysis predicted local gapping of .0015” - .0035” (38 µm – 89 µm) at joint heel at the nominal 9,200-lb  (41-kN) band tension, depending on the stiffness (or constraint) of the interfacing structure on each ring. Our FEM showed that this gap was an artifact of the hoop compression stresses of higher band tension on our ring geometry, with negligible effect on system stiffness. The load and location at which “true” gapping occurs were also predicted by FEM (see Figure 12). At an axial load of 67,500 lbf (300 kN) (about 2.7 times ESPA Grande equivalent axial loads, not shown on chart), a gap forms at the heel, such that only a small contact point at the toe remains, changing the system stiffness to ~ 1.27E+06 lbf/in  (222 MN/m).    Stiffness Predictions  Sub-24” LPSS  (Averaged over 25,000 lb  (111 kN) ESPA-Grande  equivalent tensile load  limit )  ___________________  Axial Tension   2.1 x 106 lb/in (368 MN/m) 

Axial Compression  2.6 x 107 lb/in (4.6 GN/m) 

Radial   4.0 x 106 lb/in (700 MN/m) 

Moment (in-lb/rad)  1.0 x 109 in-lb/rad   (110 MN-m/rad)
343 Summary / Conclusion  Using an understanding of the design features of a robust clampband system, we were able to scale a  heritage design, reduce profile, and increase stiffness and load capability. Design and analysis of the sub-24 Low-Profile Separation System are complete, and engineering hardware has been assembled (see Figure 12). At the time of this writing, the sub-24” system is poised for development testing in early 2012 to confirm the analysis results and determine the true load capability. 

Figure 12: Engineering Development Unit of sub-24" (LPSS) and FEM 

References 

1. Wikipedia.org, “Marman Clamp” search word.  2. Morse, B & Wittmann, A “Shear Load Carrying V-Clamp for Spacecraft Application”, 1992. 3. NASA, GD-ED-2214, “Marman Clamp System Design Guidelines”, pp 4.  4. GOES-IJK Separation System Study, Astrotech Space Operations Inc, February 1987. 5. GOES-IJK Separation System Study, Astrotech Space Operations Inc, February 1987. 6. Marman Clamp Design, J.O. Mayor, SAI, April 1991. 7. GOES-IJK Separation System Study, Astrotech Space Operations Inc, February 1987. 8. GOES-IJK Separation System Study, Astrotech Space Operations Inc, February 1987. 9. Marman Clamp Design, J.O. Mayor, SAI, April 1991. 10. NASA, GD-ED-2214, “Marman Clamp System Design Guidelines”, pp 5. 11. GOES-IJK Separation System Study, Astrotech Space Operations Inc, February 1987. 12. GOES-IJK Separation System Study, Astrotech Space Operations Inc, February 1987, pp D-2. 13. Pegasus-SELVS, Clamp Band Design Philosophy, Brian Morse, OSC, December 1992. 14. GOES-IJK Separation System Study, Astrotech Space Operations Inc, February 1987. 15. Purdy, W & Hurley, M “The Clementine Mechanisms” Presented at the 29 th Aerospace Mechanisms  Symposium, May 1995.  16. Stadnick, S. “Analysis Techniques for V-Band Coupling Designs”, Hughes Aircraft Company, April  1975.  17. Lessick, D & Marrujo, T “ESPA Rideshare Users Guide”, Department of Defense Space Test  Program, May 2010.
345 Ares I Linear Mate Umbilical Plate and Collet 

William C. Manley*, Gabor J. Tamasy* and Patrick Maloney* 

Abstract 

This paper will present umbilical carrier plate design and testing performed at KSC for the ARES 1 Upper Stage. The focus will be on the innovative linear mate ground carrier plate and electric solenoid actuated collet mechanisms. The linear mate ground umbilical plate is a unique, two-piece, design where an outer plate is first aligned and locked to the vehicle, and then an inner plate translates to engage the commodity connectors. The collet uses a spring-loaded over-center mechanism and redundant electric solenoids to release a traditional collet locking device. A high level discussion of the umbilical arm will also be presented as a corollary to the umbilical plate designs. 

Introduction  Umbilicals discussed in this paper were designed to support the Constellation Program Ares I launch vehicle shown in Figure 1. The Constellation program was initiated in 2006 to build a human rated launch vehicle to replace the aging Space Shuttles. The Kennedy Space Center (KSC) Launch Pad was redesigned for the Ares I rocket to use the clean pad concept. The launch tower is now located on the Mobile Launcher (ML) platform, as shown in Figure 1. The launch tower was designed to house the T-0 umbilical arms, T-0 sway damper and stabilizer, and the crew access arm, along with all the ancillary support equipment.                                                         * NASA Kennedy Space Center, FL 

Proceedings of the 41st Aerospace Mechanisms Symposium, Jet Propulsion Laboratory, May 16-18, 2012
346   Figure 1.  Ares I Vehicle on Mobile Launcher  The umbilical arms utilize a tilt up counterweighted configuration and rotate up as the vehicle rises from  the ML. The tilt-up umbilical arm (TUUA) design is shown in Figure 2. This is relevant because the motion of the arm for connecting and disconnecting from the vehicle is a major driver in the design of the ground umbilical carrier GUCP (umbilical plate) and the linear mate mechanism. The GUCPs are located at the end of the TUUA umbilical arms. A typical GUCP (Ares I Instrument Unit) is shown in Figure 3. The GUCP houses the QDs for transferring fluids, ECS (environmental control system), and electrical power/data between the ground and the vehicle. In this innovative design, the two primary functions of the GUCP are separated. The first function of attaching to the vehicle is done by the Outer Plate (OP) and the second function of transferring commodities between the ground and vehicle is done by the linear mate Inner Plate (IP). The other innovative mechanism introduced in this design is the fail safe T-0 solenoid actuated collet which structurally connects the GUCP to the vehicle during ground operations. These umbilicals have the potential to improve the performance and reduce the cost of the next NASA rocket to launch from Cape Canaveral.
348 GUCP Function and Mechanisms  The umbilical has two primary functions. One is to transfer fluid commodities and electrical power/data  between the rocket and ground. The second is to provide a safe T-0 disconnect to remove the commodities connections at the time of launch.  Connecting the Umbilical  In this design the outer plate (OP) provides the connect/disconnect function from the vehicle and the  structural interface designed for ease of connection and safe disconnection at T-0.   Connection of the GUCP to the vehicle is done in the VAB (vehicle assembly building). To make the  connection operation ergonomically friendly, it is preferred to have the GUCP in a tilted back (foot-forward) orientation shown in Figure 4. The GUCP starts in a 10° tilt back position and is extended by actuators on the TUUA toward the vehicle with the pivot feet at the bottom being the leading portion. In this process the technician guides the GUCP forward and visually verifies that the pivot feet are aligned to the vehicle perch (foot bracket). After the pivot feet are engaged, they form a hinge, which allows the GUCP to pivot up to the vertical (0°) position as it is being pushed forward. At this point the collet located at the top of the OP is engaged to lock the GUCP to the vehicle's flight umbilical plate. The linear mate mechanism makes this process much easier by allowing the QDs to be retracted and not in contact with the vehicle while the GUCP is being connected. After the outer plate is connected to the vehicle, the linear mate mechanism is used to extend the inner plate (IP) and plug-in all of the ground connections in one motion. The components of the linear mate mechanism are shown in Figure 5.
350   Figure 5.  Linear Mate Mechanism Details  The linear mate mechanism consists of a series of parallel linkages that move the inner plate  approximately 38 mm (1.5 inches). The inner plate is supported on eight needle roller bearings shimmed for a precise alignment and smooth in/out translation. The linkages are moved by turning the actuation nut with a standard 1-1/8 inch wrench as shown in Figure 6. In the mated position the load bearing linkages are in a straight (singularity) position which transfers all of the reaction loads into shear on the pins and has zero forces in the latching (gold) and horizontal (blue) linkages in Figure 5.   The 6061-T6 Aluminum 6061 plate carries up to 44,500 N (10,000 pounds) of separation load when all  lines are pressurized. The deflection and stresses in the plate and mechanism were analyzed with FEA (finite element analysis) to ensure they were within acceptable safety margins. Deflections of the inner plate were limited to 1/8 inch and all the components have a minimum stress safety factor of 2:1 for yield.  Complexity added by the linear mate mechanism is more than overcome by the problems that it solves.  The two-step mate operation provides high confidence for technicians by aligning the umbilical prior to  mating the critical connections. Linear engagement allows mating of fluid and electrical connectors in the same operation. Previous angular mate umbilicals made electrical connections in a separate operation after the initial mate.
351   Figure 6.  Linear Mate Mechanism Engagement – Inner plate translates to engage commodity  connectors as actuation nut is manually rotated.  Mechanism is locked with two ball lock pins and remains  locked through launch.   Disconnecting the umbilical  The TUUA arm is passively (counter weight) biased to tilt up and pull away as the GUCP releases. At T-0  the command is given to release the collet. First the GUCP pivots away from the rocket approximately 10° about the hinge line of the pivot feet. Once the GUCP has pivoted, the toe of the pivot foot is no longer engaged with the vehicle receptacle. At this point the TUUA pulls the GUCP away from the vehicle and begins to tilt-up to the retracted position. The rise of the TUUA/GUCP is tuned to match the speed of the vehicle. It takes approximately 4 seconds to disconnect and stow the GUCP.   Ideally there is no net force applied to the vehicle during disconnect (some small forces may be present  due to vehicle drift and other misalignments). The linear mate mechanism is in the forward (plugged-in) locked position during disconnect, resulting in an angular separation of the QDs. Compliance in the QDs allows for an angular disconnect. This was verified through extensive testing with the prototype GUCP to make sure no QD damage occurred during angular disconnect.  Fail safes are built into the design. In case of a collet release failure, a frangible pin is sheared by the  vehicle motion which releases the GUCP. Force for the secondary release is transferred to the GUCP from the TUUA by a wire rope. A high momentary load is transferred to the vehicle during the secondary release.  After release, the GUCP is retracted into a safe house where it is protected from the rocket exhaust blast  forces and contamination. Figure 2 shows the retract sequence. A cover plate is extended over the QDs, which are facing up after retraction, to environmentally seal and protect them from the rocket exhaust. After launch the ML is returned to the VAB where the GUCP is inspected and refurbished for the next launch.
353 An electric solenoid is perfect for this application since they can exert a lot of force but only over a small  distance. In this case, a pair of commercial-off-the-shelf (COTS) solenoids were wired into independent circuits for redundancy. Each solenoid sits adjacent to one of the linkages in the mechanism. When 60 VDC is applied to the solenoids, each one applies over twice the expected force to drive the linkage past center. The stored energy in the spring then pulls the coaxial pin out of the collet fingers. An elastomer bumper is installed to absorb some of the impact from the pin.  A prototype of this collet mechanism was fabricated by the in-house machine shop at KSC and has  undergone some preliminary testing. When both solenoids are energized simultaneously, the collet mechanism is released from the receptacle in about 8 ms. If only one solenoid is energized, to simulate a failure of a solenoid, the collet releases in about 12 ms. During the Ground Umbilical Carrier Plate testing mentioned later in this document, the collet underwent over 150 mate/de-mate cycles without any degradation in performance. With only a few launches per year for the Constellation program, this simulated over 20 years of use. Only some minor wear due to abrasion was noted at the pin and collet interface. 

Figure 8.  Solenoid Actuated Collet – Locked to vehicle receptacle
354   Figure 9.  Solenoid Actuated Collet - Locked and Unlocked Positions   Even though it is Ground Support Equipment (GSE), the collet uses NASA-STD-5017, “NASA Technical  Standard: Design and Development Requirements for Mechanisms” for design of flight mechanisms as guidance. All rotating joints feature redundant rotating surfaces and sliding joints are coated in friction-reducing material. The stored energy in the spring is more than twice what is expected to release the pin and each solenoid exerts twice the expected force on the over-center mechanism. These design details result in an extremely reliable mechanism for releasing loads of up to 44,500 N (10,000 lb). The solenoid actuated collet has other applications, such as a replacement for high cost pyrotechnic release devices.  Testing and Lessons Learned  Development of the linear mate GUCP was conducted through a series of design and test prototypes which incrementally demonstrated the efficacy of this design. Lessons learned from previous programs were used throughout the design to improve the operation and safety of the umbilicals.  One of the first items tested was the counterweighted tilt up arm design. A full scale prototype TUUA was  built and tested with our Launch Simulator as shown in Figure 10. This testing proved the original design  concept, helped validate the dynamic models, and pointed out some needed design improvements such as shock absorber sizing, and GUCP attachment strut design improvements.
355   Figure 10.  Prototype TUUA Testing  This sequence of connecting and disconnecting the umbilical incorporated many of the lessons learned  from previous programs. Experience from the Shuttle program Tail Service Masts (TSM) umbilical drove the pivot foot design and alignment method, allowing the new design to eliminate the laborious adjustment of the GUCP pivot foot. Umbilical mating actuators were also built into the TUUA to make positioning of the heavy (nearly 400 lb) GUCP much easier.   Other critical components were tested, such as the electrical and fluid QD angular mate and demate  functions. Some of this testing is shown in Figure 11. It was discovered that angular mating, which was the traditional method in previous umbilicals, was going to be a problem. Previous systems required fluid connectors to mate through a low angle as the plates were joined. Physical restrictions required a much higher mate angle for the ARES I umbilicals. Electrical connectors were damaged and the critical cryogenic fill QD did not align properly.
356   Figure 11.  QD Mate/Demate Testing  The linear mate mechanism was the solution to the problems discovered during angular mate testing.  Angular demate was still possible because of the extraction motion from the receptacles did not require a  precise alignment. Angular compliance in the QD design allowed for the 3 °-5° rotation during disconnects.  Once the design of the linear mate GUCP was completed, a fully functional prototype was built and put  through extensive functional testing. A special test fixture was built, shown in Figure 12, to simulate mating and demating dynamics, measure loads, and verify all the functions of the GUCP. 

Figure 12.  Umbilical Plate Test Fixture  Experience with the Saturn and Shuttle swings arms, and the Shuttle ET (external tank) vent drop down umbilical was incorporated during the design of the TUUA. The design of the TUUA and linear mate GUPC eliminated many of the drawbacks of these previous systems, such as the complexity of the drop
357 down design, and the much more fail safe tilt up motion of the arm vs. APOLO swing arms which could  endanger the vehicle during a retraction failure. Another lesson learned and corrected in this design was the operation where the Space shuttle umbilicals plates were connected first, then the electrical connectors were installed. The separate operation avoided the angular mate problems, but created extra work, delays and higher cost.  Conclusion  Over the 4 year period since the start of the Constellation program KSC has developed a new generation of improved state of the art umbilicals. These new umbilicals draw on 40 years of experience and incorporate many improvements such as the TUUA, linear mate GUCP, and solenoid actuated collets. These umbilicals have the potential to improve the performance and reduce the cost of the next NASA rocket to launch from Cape Canaveral.  Complexity added by the linear mate mechanism is more than overcome by the problems that it solves.  The low risk two-step mate operation provides high confidence for technicians. This umbilical combines the precision alignment of a linear umbilical with the simple demate function of a traditional angular umbilical. Linear engagement allows mating of fluid and electrical connectors in the same operation.  The solenoid actuated collet is a new method to reliable release a high load. The use of redundant  solenoids is an all new method for T-0 umbilical systems. The combination of the release and engagement function into a single over-center mechanism is the key to the simple operation. The solenoid actuated collet has the potential to replace many high cost pyrotechnic release devices.   The development effort is not over. In the next phase a fully flight certified version of the umbilical is being  built and scheduled to be completed in early 2012. This umbilical will be fully functionally tested at KSC using a vehicle motion simulator with cryogenic fluid transfer, and will be put through a full range of launch, abort, and simulated environmental conditions. The collet will also be used during this test providing more valuable data and life cycle testing. The goal is to use it for the future SLS (Space Launch System) rocket to be launched from KSC.
360 signals for the resolver across the slipring interface was a potential source of, or contributor to, the  WindSat on-orbit spin anomalies [2].    

Figure 1. The completed Flight 1 SMA Assembly   The SRA is mounted on the top of the SMA drive and provides an electro-mechanical interface to pass all of the GMI instrument electrical signals and power from the spun-side payload (RF receiver signals, power, telemetry, etc.) across the spinning interface to the stationary-side of the GMI instrument to the GPM spacecraft. The SRA consists of a preloaded angular contact bearing pair, gold-on-gold, double v-groove type brush to ring design, with a total of 124 electrical circuits (rings), and it is wet lubricated. A despin shaft with bellows coupling is used to provide the mechanical despin interface to the stationary upper instrument calibration assembly structure and provide a slight misalignment capability between the bearing pair in the SMA drive and the bearing pair in the SRA. Bearings, lubrication, and material choices will be discussed later in this paper along with the selection and sub-assembly level testing of the drive components. The completed SMA drive is approximately 8.6 inches (22 cm) in diameter by 24.15 inches (61.34 cm) long from the instrument interface base to the top of the SRA, See Fig. 2. A brief overview of the control system architecture and SMA drive electronics will also be described briefly later on in this paper.  

Figure 2. Cross-section view of the SMA
363  

Figure 3. Cross-section of the GMI Instrument Bay Structure (IBS) with the SMA installed  

Figure 3 shows a cross-section of the primary structural elements of the SMA within the GMI instrument.  A critical factor in the final configuration of the instrument architecture was the analytical determination that the GMI Instrument Bay Structure (IBS) would have to be restrained for launch in order for the SMA bearings and design to remain the same as the heritage drive. Substantial effort and care was taken in the IBS design and structural analysis to ensure that the load path from the IBS launch restraints, to the IBS structure, and transferred thru the SMA structure during launch were maintained to acceptable levels to meet adequate margins of safety with modeling and testing uncertainties.    The SMA drive design was also analyzed for adequate stiffness to meet the deployed frequency first mode requirement after the launch restraints and main reflector have deployed on orbit. Figure 4 shows the stowed and deployed structural analysis Finite Element Models (FEM) used for the stowed and deployed stiffness determination and the first modes, respectively.                            

Figure 4. Finite Element (FEM) model of GMI instrument with SMA and launch restraints meets the  first mode stowed frequency requirement (>50 Hz), meets the first mode minimum deployed  frequency requirement (>6 Hz) predicted on-orbit  De-spin Mechanism  Bellows (SRA inner  shaft to de-spin  capsule)  Bellows (SRA inner shaft to torque tube) Slip Ring Assembly (SRA)  (SRA Frame base attached to  SMA resolver housing)  SMA Resolver Housing  Torque Tube  Scan Mechanism  Assembly (SMA )  SMA to ISS interface