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Resolving Projectile Fracture with Piccolo Igniter for 40mm KE Ammunition

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Explore how a piccolo-type igniter successfully reduced negative differential pressure in 40mm KE ammunition, solving projectile fracture issues. Results, causes, and adopted approach are discussed, along with evidence and achieved outcomes.

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Resolving Projectile Fracture with Piccolo Igniter for 40mm KE Ammunition

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  1. Reduction of the Negative Differential Pressure by Using a Piccolo-type Igniter to the 40mm KE Ammunition 2003. 10 Presented by Myung-Jun, Lee Agency for Defense Development, Korea

  2. Contents • The projectile fracture experienced. • What’s the problem? • Negative differential pressure • The approach adopted. • Results achieved

  3. 40mm APFSDS-T Ammunition

  4. The projectile fracture experienced • In-bore security problem • Evidence • Footprints in yaw cards(hard boards) • Still video records • Doppler radar data • Recovered debris

  5. The projectile fracture experienced(2/6) • Footprints in yaw cards • @ 20m fr. Muzzle • Penetrator broken into 3 pieces

  6. The projectile fracture experienced(3/6) • Footprints in yaw cards • @ 20m fr. Muzzle • Broken penetrator • Fin Missing

  7. The projectile fracture experienced(4/6) • Footprints in yaw cards • Normal marks • @ 20m fr. Muzzle • (center) penetrator with a stabilizing fin 3 rounds • (left below) sabot • (right up) sabot

  8. The projectile fracture experienced(5/6) • Still video records • Fractured projectile • @ 7m fr. Muzzle • Sabot + penetrator + fin

  9. The projectile fracture experienced(6/6) • Still video records • Normal projectile • @ 7m fr. Muzzle • Penetrator/fin + sabot(3 pieces)

  10. What’s the problem? • Probable Causes • Defects • Design error • Unexpected high pressure • The others

  11. What’s the problem?(2/5) • Defects • NDT • Penetrator • Sabot • Stabilizing Fin • Alignment gage test • Complete round

  12. What’s the problem?(3/5) • Design characteristics • Maximum design strength • 80,000psi • Stress concentration • Designed to avoid as possible • Safety factor (estimated) • SF= 2.0

  13. What’s the problem?(4/5) • Unexpected high pressure • Measured max. pressure: 65,000psi • Piezotransducers: PCB • Gage Locations: 90mm, 280mm from RFT • Max. design strength  calculated strength

  14. What’s the problem?(5/5) • The others • Negative differential pressure(NDP) • Pressure history curves  yes

  15. Negative differential pressure • NDP • Gage locations -Rear:@ 90mm -Fwd:@ 280mm from RFT • Pmax 65,000 psi • -p  25,000 psi • Abnormal burning

  16. Negative differential pressure(2/2) • Anther evidence was found • Cartridge case • Rear face of the cartridge case • Blow back marks

  17. The approach adopted • Primer redesign • Button-type  Piccolo-type • Base burning  Center-core burning

  18. The approach adopted(2/4) • Design parameters • No. of holes in the flash tube • Length of the flash tube • Diameter of a hole • Hole distribution pattern • Ignition propellant (type, quantity)

  19. The approach adopted(3/4) • Piccolo-type primer • Length: 240mm • Ignition propellant • Benite strand • Weight: 8.0g • No. of hole: 16 • Hole pattern: 4-row • Diameter of a hole : 3.2mm

  20. The approach adopted(4/4) • Test apparatus • Transparent window • Grid • Primer • (above)before firing • (below) after firing

  21. Results achieved • Hole opening phenomena • High speed digital video camera • Frame: 4,000frames/second • 5.0msec after percussion (firing) • (above) Button-type • (below) Piccolo-type

  22. Results achieved(2/4) • Pressure history • Button-type primer • Pmax = 56,000psi • -P = 15,000psi • Gage locations -breech: @90mm -base: @280mm • Multi peaks

  23. Results achieved(3/4) • Pressure history • Piccolo-type primer • Pmax = 55,000psi • -P = 2,000psi • Gage locations -breech: @90mm -base: @280mm • Mono peak

  24. Results achieved(4/4) • Finally, when the piccolo-type primer was used in 40mm KE ammunition, the in-bore security problem has been resolved. • No blow back marks in the rear face of the cartridge case • No multipeaks in pressure history curves • No NDP in pressure history curves

  25. Thanks The above porcelain is a goblet which depicted a knight on a horse and is assumed to be used for drinking wine or something at the oath ceremony in ancient Korea.

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