ai-aerospace/ams_data_full_2000-2020 huggingface dataset:
196 While performing the prototype testing with the 0.016- in (0.41- mm) restraining wire, the BCIS was tested to  very extreme conditions to  draw out any other potential issues.  This included using various actuation  currents, test temperatures, and vibration levels. Based on this testing, the next limiting component in the  design was the spools. The heritage  design used a spool  that was made of a glass -filled Torlon and reacting  against it was a metallic plunger with an edge that only had a small radius. Due to the low loads on the  plunger, this was not seen as an issue as there were never any signs of indentations  or any other  observable issues . However,  when testing at extreme environments, the additional wear from higher level  environment  and temperatures , revealed a new failure mode . High-speed video revealed that the  restraining wire could fully unwind, and yet the spool would temporarily not move ( Figure 3) . While this was  only temporary, it would fail to meet the customer commut ation time requirement.  

Figure 3: Unwound Restraining Wire with  No Movement  

From the hi gh-speed video it was evident that the slow commutation time was related to either  the spool - to-insulator interface, or the spool -to-plunger interface. It was determined that the lowest risk approach  would be to replace the plas tic spools with metallic spools. This would create a better coefficient of friction   between the three components and would eliminate the concern of any spool indentations.  Since the load  on the components was low, Aluminum 7075 was chosen. A DFMEA was held to determine potential risks  with a material change. The biggest concer n was that the metallic spools would be conductive, which could  lead to a short between the terminal T3 and the actuation circuit, as seen in Figure 4.  

Figure 4: BCIS Potential Electrical Path  

In order to eliminate this concern, a thin wall  of insulating material  was added to the insulating driver . This  added a physical barrier between the metallic plunger and the metallic spring that  contact s T3. In addition,  Restraining Wire  Fully Unwound  No Plunger Movement
197 a proprietary coating called Magnap late® HCR was applied to the spools.  This provided three benefits. The  first is that Magnaplate® HCR has high dielectic strength, meaning that it will isolate the metallic spools  from  any other metallic components . The secon d benefit  is that Magnaplate HCR increases the hardness of the  aluminum spools to above 50 Rockwell C , which is harder than the plunger. It is ideal for the spools to be  harder than the plunger, as this prevents the plunger from digging into the spools and preventi ng or slowing  release. A stress analysis was performed and showed that the stress remained well below the material  capability  for the spools and plunger  (Figure 5) . Testing was also performed to validate the results. The  testing showed that the spool and p lunger combination could sustain loads over 900 lbf  (4000 N) , while the  load during use was expected to be on the order of 44 lbf  (2 N) . 

   Figure 5: FEA of the Spool and Plunger  

The final benefit is that Magnaplate® HCR is self -lubricating , with a published coefficient of friction of 0.35  when used in combination with aluminum. Since the plunger is stainless steel, it is likely that the actual  coefficient of friction between the plunger and Magnaplate coating is less. A cros s-section of t he final design  is shown in Figure 6. The design meets t he primary design requ irement of fitti ng within the initial envelope  and it has  passed all initial development tests.  

Figure 6: Final BCIS Design 

Test Results  

As of the end of 2019, the unit has successfully completed prototype and development testing. The  development testing included the following:   • 40+ actuations   o Actuation Current = 1.5 amps and greater
198 o Temperature = - 70°C to +130° C  • Vibration Testing :  o Sine Vibration: Up to 110G   o Random Vibration: Up to 56 Grms   • Shock Input   o 2300G from 1300 Hz to 10000 Hz   • Thermal Shock:   o -62°C to +137°C  o 10 cycles  

Qualification testing will be conducted in April 2020 and is expected to be completed by May 2020. The  expected qualification sequence is  in Table 1.  

Table 1: Qualification Test sequence  

Conclusions and Lessons Learned  

1. EBAD has developed an updated NEA BCIS design that is insensitive to extreme environments  and actuation conditions (within reason)   2. During the initial phase of a program, parallel paths should be chosen to reduce the impact of  unforeseen risks   3. Perform mini design review s, DFMEAs, etc. early and often to prevent spending resources on risky  design concepts   4. The force margin on even the smallest components should be determined
200 It was decided that this air cannon should use a portable air compressor  or “shop air” in the range of 400  to 800 kPa. Early experimentat ion with burst disks showed that metal foil  disks yielded erratic results  at  these pressures  and they tend to shed foil debris which cause s serious problems  for some types of   electronic fuzes.  Conventional electromechanical pneumatic  valves were ruled out due to slow opening  times.   Given the drawbacks noted above, Electronics Development Corporation  elected to develop a novel type  of pneumatic valve that  offers fast pressure rise times comparable to burst disks yet be simple and  inexpensive.  This valve is  self-locking against pressure when closed yet be self -energized when opening.    Design   The schematic design of th e air canon is shown in Figure 1. Pressure is  supplied by a 75 L pressure vessel   with a 50 mm diameter opening. The valve inlet a nd outlet apertures are also 50- mm diameter. Downstream  of the valve the aperture increases to 75- mm diameter for the breech and the barrel.  

Figure 1: Schematic Arrangement of air cannon   The valve’s components  are arranged as shown in Figure 2. The valve consists of an inlet and an outlet  aperture, a flapper element, the flapper linkage, and an impact absorber.  A pneumatic actuation cylinder  and a trip lever are mounted on the rear of the valve and may be seen in Figure 3.
201   Figure 2: Physical arrangement of valve   In order for the valve to achieve the self -locking and self -energizing requirements a design variation on the  classic four -bar linkage was chosen  as shown in Figures 4 and 5. This linkage  (a-b-c-d) goes over center  (angle b- c less than  180o) to lock against the pressure force but only requires a small external torque to trip  

Figure 1: Resetting the valve  the mechanism out of the over center lock whereupon the pressure rapidly throws the valve open.  An impact  absorber is provided to stop the moving linkage when opened.  If the over center angle is kept small very  little torque is required either to trip the valve or to reset it. The torque to actuate the valve is supplied by a  small pneumatic cylinder  attached to the back of the valve. This version of the valve is simply reset by hand  as sh own in Figure 3.   

Impact  Absorber  Linkage  Flapper  Inlet  Aperture   Outlet  Aperture  Pressure   Transducer
203 Testing   A sample pressure curve is shown in Figure 6. Of note is the rapid pressure rise time of ~10 ms. While this  is not quite as fast as a burst disk it is much faster than the majority of electromechanical pneumatic valves  of similar aperture. The 75- L pressure vessel  completely empties in ~200 ms.  

Figure 6: Sample pressure curve  Live fire tests with 1- kg dummy test projectiles showed that the desired muzzle velocity of 75 m/s is easily  achieved at ~250 kPa pressures using a 3- m barrel.  100 m/s is possible using the full 400 kPa max  operating pressure.  

Field Use  

The first field use of the finished 75 mm air cannon was testing prototype munitions fuzes by mounting them  into test projectiles and shooting them past targets of interest . Figure 7 shows  one of the  test setups (note  the barrel in the foreground.)  This testing required hundreds of shots to be fired in as rapid a succession  as possible. The valve held up extremely well with no misfires or other mechanical deficiencies. No  adjustment s to the valve were required throughout the testing.
204   Figure 7: Use in the field  

Conclusions   The valve  for the 75- mm air cannon  has met or exceeded all requirements. The over center four -bar linkage  is surprisingly robust , needing no adjustment over the course of hundreds of shots. The valve can be  manufactured at a relatively low cost as the parts are  simple and few tight  tolerances are required.   It bears noting that this valve design is not limited to use on air cannons. The design is easily scalable and  could potentially be used in any application which requires t he rapid venting of a pressurized fluid.
205 Development of a L ow-Shock Separation Nut Out of the P yrotechnic Class 

Sebastien P erez*, Frederic Miralles * and François Degryse* 

Introduction  

About Pyroalliance   Pyroalliance is the European leader and a world- class player in pyrotechnics and mechanisms, delivering  innovative and cost -effective solutions tailored to our customers’ critical requirements. With more than a  half-century of experience as a manufacturer of state -of-the-art pyrotechnic and mechanical equipment,  Pyroalliance addresses the requirements of cutting- edge industries, including Aerospace, Defense and  Energy. We leverage our proven expertise and innovative mindset to develop products that combine the  performance and reliability needed to perform critical functions for our cust omers’ systems.  

Facts and figures:   • Counting over 240 collaborators, Pyroalliance is operating from two locations. The headquarter s  is at Les Mureaux (Region of Paris) and the second site is located in Toulon (Southe ast France)   • Pyroalliance is 90% owned by ArianeGroup, the remaining 10% be longing to the company OEA  Inc.   • The company has reached 40 million Euros turnover in 2018, representing a 15% growth  compared to 2017   • Exporting in more than 15 countries, Pyroalliance is pursuing its international growth  

Low-Shock Separation nuts   By adapting the design of its Pyrotechnics Nuts, Pyroalliance overcomes the preconceived notions and  changes the game by claiming its products are Ultra Low Shock.  

Pyroalliance has been desi gning and producing Pyrotechnic Nuts as well as Hold and Release  Mechanisms  for decades. Those are dedicated to maintain satell ites on dispensers as well as antennas  and booms on satellites. To date, Pyroalliance has delivered more than 6000 of those with a track record  of 100% operational success. Indeed pyrotechnic nuts provide major operational benefits thanks to their  very high energy density, very high standard of proven reliability, speed of execution (milliseconds scale)   and ideal synchronicity when several nuts are to be activated simultaneously (typical situation when  satellites are h eld on a satellite dispenser).  

Recent market surveys show that:   • Separation Nuts require a growing capability to reduce levels of shocks on the payloads, what is  considered as an attractive feature for sensitive payloads, combined with an ability to ensure  synchronicity;   • Despite of their performance, a growing number of actors of the New Space are reluctant to use   equipment classified as pyro for operational reasons.   Understanding those challenges , Pyroalliance presents hereafter its recent achievements in those areas .    

* Pyroalliance, Les Mureaux, France;  sebastien.perez@pyroalliance.com,  frederic.miralles@pyroalliance.com, francois.degryse@pyroalliance.com  

Proceedings of the 45th Aerospace Mechanisms Symposium, NASA Johnson Space Center, 2020
206 Separation Nut Background  

Pyroalliance designs , manufactures and delivers  separation nuts or complete Hold and Release  Mechanisms  meet ing the requirements of various  mission profiles . However, each design is based on the  same principles  which have cumulated decades of flight heritage .  

Figure 1. Pyroalliance separation nuts – Principle  

Functioning  principle : The pyro- initiators make the pressure increase inside the sealed chamber, until  the release piston can translate. When shifted, the release piston, due to its inner geometry, allows the  radial expansion of the thread segments and, consequently, the release of the s crew. At the same time,  the ejection pin moves and ensures that the screw cannot remain or move back to  its initial location.   

Pyroalliance separation nuts are fully reset table on both Pyroalliance sites or customer facilities  using  cold gas (non pyro gas ). The Spring allows reset ting the parts in the initial position when actuated by cold  gas. Before delivery , 100% of our separati on nuts are controlled using  cold gas  actuation in a test set  reflecting the extreme operational conditions  of the mission (temperature and pre -load at release).  

The heritage design has the following main advantages:   • Outstanding reliability figures (> 1 – 5x10-5) despite extreme operational  conditions ; the simple  design made of  only a few parts and the motorization margins driven by the pyrotechnic s are the  key features enabling such level of reliability   • Extremely low  actuation time / actuation time standard deviation:  the actuation time of  Pyroalliance separation nuts remains  below 2 ms cumulating both contributions of pyrotechnic  and mechanical actuations . Then, the actuation time standard deviation is well below 1 ms which  is particularly suited  for multi -point release.   On top of those advantages, Pyroalliance recently started  to implement some adaptations to this heritage  design in order  to meet new emerging market requirements . They aim at :   • Reducing the level of shock induced on the holding structures  during the releas e   • Performing the necessary steps to make the device Out of Class (non pyro).   Pyroalliance is curently working o n implementing those adaptations while preserving all assets of the  heritage design.    Release pistonCombustion chamber Thread segmentEjector SeparatorSpringHousing BaseInitiator
207 Pyroalliance achievements 

First analysis   When analyzing the separation nut heritage design,  Pyroalliance made the assessment  that there were  three main contributors to the induced shock :  • Pyrotechnic shock due to the initiator actuation   • Strain energy stored in the screw during  the preload and freed during the release   • Kinetic energy stored in the release piston during the release and further distributed during  following shocks of the piston with other mechanical parts .  Table 1 summari zes the different contri butor s of the shock and quantif ies their respective impact. The  considered design is the heritage M10 separation nut (screw diameter: 10 mm / 0.39 inch) . 

Table 1. Shock contributors assessement – M10 separation nut heritage design   Shock source  Nature  Shock contribution*   Initiator actuation  Pyrotechnic  10% (tested with NASA Standard Initiator  / Space Standard  Initiator )  Screw release of  the preload  Mechanical  5% (preload: 20  kN ; screw length : 100 mm ; screw material:  stainless steel)   Impact of the  release piston  Mechanical  85%  *Note: Several tests / ana lysis have been performed in order to quantify the impact of each contributor.  

Pyroalliance found out  that the shock was  mainly caused by the impact of the release piston at the end of  his stroke once the threaded segment s are expa nded.  

As an ex ample, the sketch on  Figure 2 presents the c haracteristic of the piston collision  using  the  M10  separation nut . The velocity of the piston at the time of the impact has been captured using a high- speed  camera.  

Figure 2. M10 separation nut –  Collision characteristics      Impact characteristics •Release piston mass: 50g •Release piston velocity: 30 m/s •Kinetic energy: 22.5 J
208 Addition of a damping system   Based on those findings, Pyroalliance designed a specific damping system made of a dedicated damping  material and located after the release at the end of the release piston stroke. This system allows  performing a progressive braking of the release piston without degrading the reliability of the global  syste m. 

Furthermore, this damping system is fully compliant with respect to LEO space requirements:   • Outgassing compliant with NASA / ESA Standards   • Tested on the temperature range [ -60°C;+80°C] without any performance degradation   • Compatible with a 10 years storage duration without any performance degradation (tested  through accelerate d aging ).  Pyroalliance has performed several tests with the addition of the damping system. The shock  configuration is  composed of an aluminum plate of 1m×1m× 5mm receiving the separation nut test  assembly. Four accelerometers are distributed on a 100- mm-diameter circle around the separation nut.   

Figure 3. Shock test configuration – M10 separation nut
209 The results are presented on the Figure 4. 

Figure 4. Shock Response Spectrum - Addition of the damping system  

These results have been measured o n Pyroalliance own shock test lab configuration. A comparison of the  shock with / without damping system has been performed in the exact same configuration considering  several units. The induced shock has been reduced by a factor 4 on the frequency band   [1000 Hz; 10000Hz].  Furthermore, the damping system brings  similarly better  results on the entire  frequency range.  

Tests have also been performed  on a spacecraft mockup at customer level . The accelerometers were  located on the spacecraft side close to the cup / cone interface . The results  measured by the customer  were the following:   - 4000 g SRS @2000Hz with the heritage design (without damping);   - 1000 g SRS @2000Hz with the addition of the da mping system.   The shock reduction by a factor 4 measured on the shock test lab configuration has therefore also been  verified with the same ratio at customer level.  

Pyroalliance is pursuing this effort to improve the damping system and reduce the shock induced by the  separation nuts  with a target of 500 g SRS @2000Hz on a spacecraft  configuration . 

Out of classification European procedure   In the context of aerospace industry, Pyroalliance is turning toward techn ologies  which contain  pyrotechnics  and its condensed power while being as safe as other non pyrotechnic devices.  

In order to be classified as non- dangerous good regarding  the law (c.f  French transport regulation law:  Recommandations relatives au transport des marchandises dangereuses ST/SG/AC.10/1/Rev.20) ,  Pyroalliance will conduct  several  tests  to demonstrate  that an unpackaged separatio n nut equipped with  pyro- initiators  satisf ies the 6 criteria  in Table 2.        1·1011·1021·1031·104g 21·1031·1041·10 Hz SRS MAXIMAX  (Q=10) - Shock comparison - M10 separation nut separation nut without damping system separation nut with damping system
210 Table 2. European criteria – non dangerous goods  transport regulation   Criterion  Content  Status  Sensor  type  Property when functioning   1 Surface  temperature  When actuated, external surface s of the product  shall  not reach a temperature higher than 65°C (149°F). A  transient 200°C  (392°F)  peak  remains  acceptable.  Checked  (measured  through tests)  Thermocouple   2 Integrity  Neither  rupture nor movement of any parts of the item,  or the item itself, should occur beyond a 1-meter range  in any direction. If the integrity can be affected by the fire  expos ure, tests under fire can be requested.  To be checked  under fire  expos ure High speed  Camera   3 Low noise  No audible effect above 135 dB at one meter from the  item in any direction.  To be checked  Sonometer   4 Arc and  flames  No electric arc, no flame should occur able to inflame  material such as a sheet of paper whose density is 80 ±  10 g/m2 in contact with the item.  To be checked  High speed  camera   5 Fumes  No producti on of fumes, emanations or dust should  occur which would reduce the visibility by 50% in a 1meter -cube chamber. The luxmeter is located at 1 meter  from a constant light.  To be checked  Luxmeter   Others   6 Inviolability  To make the item safe to manipulate even in case of  untimely firing, the design shall ensure  that the  pyrotechnic initiators can not be unscrewed from  the  separation nut, as a warrant of inviolability and safety for  operators and users.  Compliance of  design options  to be confirmed  by regulation  authorities  Conception  requirement   Note 1: If no fumes are observed during tests performed for previous criteria,  criterion 5) can be  exempted.   Note 2: The regulation authorit ies can determine that a packaged item is more dang erous than an  unpackaged one and can request  tests with packaging.  

Pyroalliance is in the process of verifying all of those  6 criteria until mid-2020 in order to submit the file  and request the EU out of class certification. Finally, Pyroalliance objective will be to transpose the EU  out of class certification to US regulation of goods by contacting US DoT.  

Conclusion  

While preserving all assets of the heritage design of its separation nuts (very high reliability and extrem ely  fast actuation time), Pyroalliance is cur rently working and quickly progressing on bringing new  advantages to its products:   • With the addition of a new damping system, Pyroalliance has already reduced the level of  induced shock by a factor 4 compared to its heritage design. As a next step, Pyroalliance is now  targeting to reach a shock below  500 g SRS @2000Hz measured on a small spacecraft  configuration   • Besides Pyroalliance aims at delivering separation nuts out of the pyrotechnic classification  (EU /  US regulation law s) by mid -2020.