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Adding an Electronic SelfAdding an Electronic SelfDestruct Mode to theDestruct Mode to the
M230 FuzeM230 Fuze
Shala M. StricklandShala M. StricklandUS Army TACOM-ARDECUS Army TACOM-ARDEC
nn As part of the As part of the D862 Fuze Technology IntegrationD862 Fuze Technology Integrationprogram to upgrade existing fuze designs, the Fuzeprogram to upgrade existing fuze designs, the FuzeDivision initiated an in-house design effort toDivision initiated an in-house design effort toincorporate an electronic self-destruct mode into theincorporate an electronic self-destruct mode into theM230 rocket submunition fuze.M230 rocket submunition fuze.
nn Program GoalsProgram Goalsnn Improved reliability of training ammo - ReducedImproved reliability of training ammo - Reduced
DudsDudsnn Existing fuze reliability 95% (5% dud rate)Existing fuze reliability 95% (5% dud rate)nn Goal of SD fuze - meet OSD policy of <1%Goal of SD fuze - meet OSD policy of <1%
unexploded ordinance on the battlefieldunexploded ordinance on the battlefield
M261 HE MPSM WarheadM261 HE MPSM Warhead
nn Part of the Hydra 2.75 rocket systemPart of the Hydra 2.75 rocket systemnn Fired by Apache and CobraFired by Apache and Cobra
HelicoptersHelicoptersnn Effective against Light Armor, Materiel,Effective against Light Armor, Materiel,
and Personnel.and Personnel.nn Main Fuze - M439 Remote Set TimeMain Fuze - M439 Remote Set Time
FuzeFuzenn Contains 9 M73 submunitionsContains 9 M73 submunitionsnn Each submunition fuzed by a M230 fuzeEach submunition fuzed by a M230 fuze
nn The M230 fuze combines a Ram Air Decelerator (RAD)The M230 fuze combines a Ram Air Decelerator (RAD)and a bore rider/slider combinationand a bore rider/slider combination
Basic M230 fuzeBasic M230 fuzeSequence of OperationSequence of Operation
nn Upon expulsion from the warhead the bore riderUpon expulsion from the warhead the bore ridersafety is removed.safety is removed.
nn The air stream forces deployment of the RAD,The air stream forces deployment of the RAD,breaking the shear wire and retracting the armingbreaking the shear wire and retracting the armingpin. Retraction of the arming pin unlocks the slider.pin. Retraction of the arming pin unlocks the slider.
nn The arming spring pushes the slider to the armedThe arming spring pushes the slider to the armedposition with the escapement providing safeposition with the escapement providing safeseparation.separation.
nn When the slider is in the fully armed position theWhen the slider is in the fully armed position thetrigger is unlocked.trigger is unlocked.
nn Upon impact the trigger releases the detent ball.Upon impact the trigger releases the detent ball.The firing pin is now free to move.The firing pin is now free to move.
nn The spring force of the firing pin causes the firing pinThe spring force of the firing pin causes the firing pinto impinge upon the M55 detonator initiating theto impinge upon the M55 detonator initiating theexplosive train.explosive train.
M230 fuze with self-destructM230 fuze with self-destruct
nn Two independent functioning modesTwo independent functioning modesnn Primary modePrimary mode – Operates in the same manner as the existing – Operates in the same manner as the existing
M230 fuze - same safe and arm mechanism and impact modeM230 fuze - same safe and arm mechanism and impact modeswitch. The fuze arms after expulsion and the M55 detonatorswitch. The fuze arms after expulsion and the M55 detonatorinitiates the explosive train & grenade at impact.initiates the explosive train & grenade at impact.
If the primary mode fails, thenIf the primary mode fails, thennn Secondary SD modeSecondary SD mode - Operates independent from arming. The - Operates independent from arming. The
electronic circuit & power source fire an electric detonator at aelectronic circuit & power source fire an electric detonator at afixed time after expulsion. The electric detonator output initiatesfixed time after expulsion. The electric detonator output initiatesthe primary mode’s M55 detonator. If the fuze is armed thethe primary mode’s M55 detonator. If the fuze is armed thewarhead functions warhead functions (self destruct)(self destruct) – if the fuze is not armed the – if the fuze is not armed thesensitive detonators are eliminated sensitive detonators are eliminated (self neutralization).(self neutralization).
IF SD and primary modes fail, timer turns off and bleed down circuit discharges electrical powerIF SD and primary modes fail, timer turns off and bleed down circuit discharges electrical power
Adds a totally independent self destruct modeAdds a totally independent self destruct mode
Modifications to the M230 Fuze toModifications to the M230 Fuze toIncorporate the Self-DestructIncorporate the Self-DestructModeMode
nn Modified the housing to move the gearModified the housing to move the geartrain and make volume for electronicstrain and make volume for electronics
nn Modified the slider to add an M100Modified the slider to add an M100detonator for SD functioning anddetonator for SD functioning andrelocated the gear teethrelocated the gear teeth
nn No changes to the impact switch, RAD,No changes to the impact switch, RAD,firing pin, or the fuze booster platefiring pin, or the fuze booster plate
nn Minor modifications to the bottom plateMinor modifications to the bottom plateof the gear train assemblyof the gear train assembly
Housing with sliderHousing with sliderand gear trainand gear train
M230 Fuze w/ SDM230 Fuze w/ SDM230 FuzeM230 Fuze
Relocation of Gear TeethRelocation of Gear Teeth
M230 fuzeM230 fuze
M230 SD fuzeM230 SD fuze
Location of SD electronicsLocation of SD electronics
Impact switch parts not shownImpact switch parts not shownCavity for reserveCavity for reserve
battery and activationbattery and activationmechanismmechanism
Self-destructSelf-destructcircuitrycircuitry
Electronic DesignElectronic Design
nn Utilizes PIC micro-controller toUtilizes PIC micro-controller toperform timing functions, andperform timing functions, andoperate 2x charge pumpoperate 2x charge pumpnn Low power consumptionLow power consumptionnn On board nonvolatile memoryOn board nonvolatile memorynn Small size - 8 pin SOIC packageSmall size - 8 pin SOIC packagenn On board flash memory can be used toOn board flash memory can be used to
“tag” ckt & prevent multiple power ups“tag” ckt & prevent multiple power upsfrom operating the circuit in dud fuzesfrom operating the circuit in dud fuzes
nn Battery bleed circuit in caseBattery bleed circuit in caseM100 detonator fails toM100 detonator fails tofunctionfunction
Assembly Language CodeAssembly Language CodeGenerated and DebuggedGenerated and Debugged
PowerPowerApplyApply
CheckCheckEEPROMEEPROM
Set flag inSet flag inEEPROMEEPROM
ExitExit
Call 4 Sec.Call 4 Sec.DelayDelay
Call 1 Min DelayCall 1 Min Delay
Fire DETFire DET Turn On BleedTurn On BleedCircuitCircuit
YESYES
NONO
Power Source OptionsPower Source Options
nn Reserve battery to activate on expulsionReserve battery to activate on expulsionnn Key Requirements:Key Requirements:
nn Electrical: 3-5 volts @ 150 Electrical: 3-5 volts @ 150 µµA TypicalA Typicalnn Active life Less than 2 minutes requiredActive life Less than 2 minutes requirednn Storage life : 10 years minStorage life : 10 years min
nn Candidates examinedCandidates examinednn Reserve battery in M234 fuzeReserve battery in M234 fuze
nn Miniature size, performed well in lab tests with the circuit,Miniature size, performed well in lab tests with the circuit,production line being setupproduction line being setup
nn Prototype OICW battery supplied by ATKPrototype OICW battery supplied by ATKnn Larger size may enhance producibilityLarger size may enhance producibilitynn Can fit into M230 design but smaller size desirableCan fit into M230 design but smaller size desirablenn Lab Tests plannedLab Tests planned
SD Circuit produces > 6 volts and exceeds detonatorSD Circuit produces > 6 volts and exceeds detonatorall-fire voltage by a large margin!all-fire voltage by a large margin!
2223344455666
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35
“No-Fire” = 1.8V“No-Fire” = 1.8V
“All-Fire” = 4.5V“All-Fire” = 4.5V
Used the Langlie Method to test 35 M100Used the Langlie Method to test 35 M100
detonators to determine “All-fire” and “No-fire” Voltagesdetonators to determine “All-fire” and “No-fire” Voltages
Lab Tests with M234 BatteryLab Tests with M234 Battery
Charging Curve of SD circuit with M234 reserve batteryCharging Curve of SD circuit with M234 reserve battery
Future PlansFuture Plans
nn Complete designComplete designnn Fabricate prototypesFabricate prototypesnn Perform rocket tests withPerform rocket tests with