Report CopyRight/DMCA Form For : Universal Dual Safe Training Fuze For Mortars
1 Universal Dual Safe Training Fuze For Mortars Presented by Michael De Gregorio Prepared by Michael De Gregorio and Eugene Mogendovich
Current Situation,Mortar Training Fuzes are only single safe and. released for use with a waiver from the AFSRB,Arm on setback. Require a pull pin for safety during transportation. Each training cartridge has its own variant of the. training fuze,60mm M769 M775 Fuze,81mm M879 M751 Fuze. 120mm M931 M781 Fuze,There is a reliability issue at charge 0 on the. During PQT of the M879 cartridge M751 Fuze a,ballistic reliability of 27 2 for charge 0 was. demonstrated,Current Design,During shipping and,handling the fuze is kept 5. safe by a combination,packing clip and pull pin 6,1 Prior to firing the pull 7. pin is removed by hand,Upon firing the 3,acceleration moves the. setback pin 2 rearward,against the spring,releasing a slider 3. which has been holding the,striker 4 in its rearward 2. Current Design,Once the striker 4 is,released it travels upward 5. allowing the ball bearings,5 to be forced into 6,central alignment between 7. the striker 4 and the,Model does not show the 3,plastic covering that keeps. the striker 4 from flying,out of the fuze once it is. Upon impact the striker,4 is driven into the ball 2. bearings 5 which,detonates the primer 6,igniting the spotting. Proposed Solution,Develop a Mortar Training Fuze that will. work across all cartridges,Add a second safety that meets MIL STD 1316. and remains low cost,Look at the use of set forward after tube exit. Will get rid of the pull pin,Optimize the current setback mechanism. for all charges on all systems,Work with Pyrotechnics and Ballistics. Groups to come up with one spot charge,for all cartridges. The Game Plan,Complete the work on the second safety. Design work,Characterize the set forward environment for. Standardize the existing first safety,Commonize set back pins. Increase the reliability of the M751 at charge 0,Standardize the spotting charge. The Road to a Second Safety,Design Concept,Drag force and gravity. deceleration during the,ballistic flight move the,set forward pin 11. forward against the,spring 12 releasing,the slider 13 which. had been holding the,striker 5 in its,rearward position the. second safety,The Road to a Second Safety,A test was held on 6 March. 2006 to prove out our,concept Rotation,rev min Gs Comment. Used the centrifuge to Striker Without Spring 446 111 Released. simulate the set forward,event Striker With Spring 638 226 Released. Found that we needed,approximately 200 Gs of force. to release the set forward,At this point we were,uncertain as to what set. forward forces we would have,to work with,Environment not. characterized for mortars,However we were certain,that we would be working. with less than 200 Gs of set,Redesign needed,The Road to a Second Safety. Work began on an,improved design,A heavier design of the. set forward pin would,lower the Gs needed,for activation of the. This design was tested,on 24 October 2006,Reduced activation Gs. from 200 to 20,Experimented with Original Dry CRC 143DF. Lubricants Design Parts Power PTFE,Still felt that the Gs Gs Gs Lube Gs Gs. needed to be reduced 226 23 2 33 4 27,Mean Values for each case 9. The Road to a Second Safety,Set forward environment hard to characterize. empirically, Ballistic test required to characterize the forces. seen on the projectile throughout its entire, Looking for a unique event that is independent from. Awaiting the fabrication of telemetry units, Once this test is complete we will know for certain. the forces that we have to work with,The Road to a Second Safety. Fuze Radius Rotation Gs Comment Tested same design. with all parts coated,1 19 200 21 6 Released,with low friction. 2 19 325 57 Rough belt Molybdenum,Disulfide Titanium. 3 19 210 24 0 Released,4 19 180 17 5 Released,Results showed that. the parts reacted,more consistently,when coated with. Mean value was 21,The Road to a Second Safety,We have completed another. Original Design Gs First Iteration Gs Second Iteration Gs design iteration. No Lubricant No Lubricant Power Lube 143DF PTFE MoS2Ti Coating MoS2Ti Coating Adjustable weight design for. testing purposes, 226 23 2 33 4 27 21 13 4 Three times as heavy as the last. Mean Values design when using the largest,extension Twice as heavy when. the smaller extension is used,Tested this design on 9 May. Mean Value was 13 4 Gs,The results of this test when. compared to the ballistic forces,that are being collected by the. telemetry units will tell us,whether or not set forward is a. viable option,A Complete First Safety, In parallel to the second safety effort an effort is. being made to fix the charge 0 reliability issues,associated with the M751. Using this as a springboard for standardizing the set. back mechanisms across all cartridges at all charges. Three solutions were looked at,Change hollow pin to a solid pin. Increase the depth of the setback chamber and the,length of the pin offset design. Implement a zigzag design in the current hardware,A Complete First Safety. Performed a drop test 12,December 2006,One accelerometer was. placed on top of the fuze,in the striker hole to,observe the forces within. the fuze during the drop,and upon impact,We then developed a. model and used this data,to verify our results,Allows us to trust the. results of our model,Offset Design,Original Design. A Complete First Safety,Case Drop Results Firing Results. Hollow Pin no offset Pass Does Not Arm,Current Configuration 27 2 historically. Hollow pin 04 offset Pass Does Not Arm,Average Weight Pin 04 Pass Does Not Arm.