second environment sensor for tube launched …...second environment sensor for tube launched...

Second Environment SensorFor Tube Launched Non-Spun

MunitionsApril 9, 2003

TTank-automotive & AArmaments COMCOMmand

LeadershipTeaming

CommunicationEmployee SupportStrategic ThinkingOrganizational Climate

Providing AmericaAdvanced Armaments

for Peace and War

John I. NickelElectronics Engineer, Fuze Division

47th Annual NDIA Fuze Conference

4/9/2003 JIN / DWW 2

Committed to Excellence

Participants

Curt Anstine, Mechanical Engineer Jim Campbell, Mechanical Engineer

Julian Knisley, Mechanical TechnicianJohn Nickel, Electrical Engineer

Dennis Ward, Team Leader Ron Wardell, Senior Electrical Engineer

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Smooth vs. Rifled BoreLaunch Environment Sensing

• First environment indicator

– Setback is a robust first environment for both artilleryand mortar rounds

• Second environment indicator

– Artillery rounds typically employ spin to sense launchenvironment and to activate reserve power sources

– Spin cannot be used for smoothbore mortars andother non-spun munitions

– Mortars often use air-driven turbines to sense air flowas a second environment and to generate power

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Alternative 2nd Environment Sensor

• Mortar and other non-spun munitions could employan electrically-sensed muzzle exit signature for asecond environment indicator

• A sealed electronic sensor would not haveenvironmental exposure concerns as turbines do

• Goal of sensor is to determine a unique tubesignature that clearly indicates a launch environment

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• RF-based 2nd environment sensor

– Active sensor that transmits RF energy, whichpropagates in mortar tube as though in a circularwaveguide

– Some RF energy is reflected back from theimpedance mismatch between mortar tube muzzleand free space

– Sensor output at any moment is the instantaneoussum of transmitted and reflected waves at that pointin the tube

– Sensor output contains velocity information

2ND Environment SensorOverview

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Sensor Development Activities

• Defined sensor architecture

• Collected data in lab on mock-ups of 60mm, 81mm, and120mm mortar tubes. Data included time-zero, sensoroutput, and tube exit indication

• Collected time-zero and sensor data under ballisticconditions on 60mm, 81mm, and 120mm mortars at APG.Data was collected using on-board recorders

• Analysis of collected data and work on sensing andprocessing algorithm development

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Sensor Architecture

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Typical Lab Test Set-up

60mm mock-up tube

Lab test vehicle

RF absorbent tominimize reflections

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Signature of MicrowaveTransmitter in a 60mm Tube

T-ZeroExit

Sensor Output

Expanded Trace

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Exit

Sensor Output

Expanded Trace

T-Zero

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Exit

Sensor Output

Expanded Trace

T-Zero

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BallisticTest #1

BallisticTest #2

RF Sensor Test Matrix

3221

1112

1113

3224

3234

3231

QtyQtyQtyCharge

120mm81mm60mm

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81mm test circuitboard and vehicle

60 / 120mm test circuitboard and vehicle

Ballistic Test Hardware

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Ballistic Test Hardware During Assembly

Test Vehicle Parts Pre-assembly testing

Potted sensor Battery Data recorder Connector cup

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Ballistic Test Results

Field test results were drastically different from labresults!

• Setback, balloting and other shocks induced high noiselevels into the circuitry

• Potting compound degraded IF signal

• Outward flaring of mortar tube lip reduced the amountof energy reflected back, thus lessening the sensitivityand effectiveness of the sensor

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Test Results - Raw Sensor Data

Sensor outputcontains velocityinformation

81mm Chg.1 (Lowervelocity)

81mm Chg.4 (Highervelocity)

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Test Results - Raw Sensor Data

Sensor outputcontains weaponinformation

120mm barrel (69.1”)

60mm barrel(35.3”)

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Test results - Raw Sensor Data

Induced noise candrastically increasewith firing charge

120mm, chg 1

120mm, chg 4

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2nd Environment SensorTask Summary

Completed:

• In-lab tube characterization tests (60, 81, 120mm)

• Ballistic environment tube measurements conductedin 60, 81, and 120mm mortar tubes at all chargeconditions and ambient temperature

• Sensor data reduction and analysis conducted

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Conclusions

Overall, the sensor shows promise, but it needs work

• Further investigation of waveguide propagationphenomena

• Refinement of detection and processing algorithm

• Redesign of RF and IF circuitry to minimize noise,temperature effects, unexpected interactions and energylosses

• Blast shield for 81mm and vehicle-mounted 120mmmortars should be included in testing

second environment sensor for tube launched …...second environment sensor for tube launched...

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