CAD/PAD Laser Ignitability Programs at theIndian Head Division, Naval Surface Warfare Center

Mr. Tom BlachowskiMr. Travis ThomIndian Head DivisionNaval Surface Warfare Center

2010 SAFE – Europe30 - 31 March 2010

Overview

Two laser ignitability programs will be discussed

• NACES USRM (MK123 Mod 0/MK124 Mod 0) EffortU. S. Navy – NACES (Navy Common Aircrew Ejection Seat)

USRM (Underseat Rocket Motor)Evaluate laser ignitability characteristics of USRM propellents

• ACES-II Rocket Catapult EffortU.S. Air Force – ACES-II (Advanced Concept Ejection Seat)New alternative propellent development effort

IHDIV, NSWC Current Capability to conduct other laser ignitability efforts

System Function

NACES Ejection Seat Test – F-14 Configuration – 15 Sep 1989 – NAWC CL

System Function

MK123 Mod 0 / MK124 Mod 0Underseat Rocket Motor

NACESEjection Seat

Laser IgnitabilityTest Approach

For all IHDIV, NSWC Laser Ignitability efforts, a consistent approachtest methodology has been adopted

• A Carbon Dioxide (CO ) laser is utilized to supply a uniform heat inputto the energetic material under test

• For the IHDIV test methodology, four differing laser input power levels are established and then, by varying the laser input pulse duration, assessmentsof the Time to First Light and the 50% Ignitability Thresholds are completed

• The “pass/fail” criteria for the 50% Ignitability Thresholds are adetermined if a “Sustained” combustion or an “Unsustained” combustionreaction is apparent at the completion of the laser pulse

2

NACES Laser IgnitabilityTest Program

• The primary objective of the NACES USRM effort was to evaluateany potential differences between the laser ignition thresholds for KU and Mechanite 19 double base propellents at ambient and at coldtemperatures.

• Specifically, this evaluation includes comparing both the 50% IgnitionThreshold and the Time to First Light (or Ignition Delay) parameters at ambient and cold temperatures for the two propellents.

• All tests were conducted at atmospheric pressure.

• Cold temperature for this test series was defined as conditioning eachsample to -75 F (-60 C) in the dewar and conducting the specific laser functional test within 15 seconds of the dewar and sample being removed from the chamber.

NACES Laser IgnitabilityTest Program

Dewar Cover Dewar Sample

HolderDewar Cover Dewar Sample

Holder

NACES Laser IgnitabilityTest Results

Example of a “Go” Test Result

Sustained Combustion Unsustained Combustion

Example of a “No Go” Test Result

The spatial power distribution from the laser was not uniform as evident in the “No Go”sample. However, this aspect was consistent throughout this test program.

NACES Laser IgnitabilityTest Results

Time to First Light vs Laser Flux

10

100

10 100 1000

Laser Flux (W/cm^2)

Tim

e t

o F

irst

Lig

ht

(ms)

Mechanite 19 (70°F)

Mechanite 19 (-75°F)

KU (70°F)

KU (-75°F)

NACES Laser IgnitabilityTest Results

Energy to First Light vs Laser Flux

1

10

10 100 1000

Laser Flux (W/cm^2)

En

erg

y t

o F

irst

Lig

ht

(J/c

m^

2)

Mechanite 19 (70°F)Mechanite 19 (-75°F)

KU (70°F)KU (-75°F)

NACES Laser IgnitabilityTest Results

50% Ignition vs Laser Flux

100

1000

10 100 1000Laser Flux (W/cm^2)

50%

Ig

nit

ion

(m

s)

Mechanite 19 (70°F)Mechanite 19 (-75°F)KU (70°F)KU (-75°F)

NACES Laser IgnitabilityTest Results

50% Ignition Energy vs Laser Flux

10

100

10 100 1000

Laser Flux (W/cm^2)

50

% I

gn

itio

n E

ne

rgy

(J

/cm

^2

)

Mechanite 19 (70°F)

Mechanite 19 (-75°F)

KU (70°F)

KU (-75°F)

NACES Laser IgnitabilityTest Results

• As expected, both the KU and the Mechanite 19 double base propellentsexhibited required significantly increased laser input power levels at low temperature to achieve sustained combustion.

• And as expected, both the KU and the Mechanite 19 double basepropellents demonstrated significantly longer reaction times at lowtemperature than the reaction times at ambient temperature.

Both propellents experienced “quenching” events when tested at -75 F(-60 C) temperatures. “Quenching” is defined as a single test resultwhere the input parameters (laser input power and pulse duration)resulted in a “Sustained Combustion” result; however, when the flamefront reached the top of the brass sample holder, the reaction was halted.

NACES Laser IgnitabilityTest Results

Ash

Unburned propellant

Brass sample holder

Ash

Unburned propellant

Brass sample holder

Example of a “Quenched” Test Result

NACES Laser IgnitabilityTest Results

Sample Quenching EventsKU Propellent Mechanite 19 Propellent

10W of 8 None of 9

20W of 10 None of 10

30W of 10 None of 9

40W of 10 of 9

NACES Laser IgnitabilityTest Summary

• For both the Mechanite 19 and the KU double base propellents,significantly higher laser input levels were required to achievesustained combustion and the Time to First Light (Ignition Delay)times were significantly longer at cold temperature that at ambienttemperature

• The Mechanite 19 propellent results exhibited higher standard deviations than the standard deviation of the KU propellent test results

• The propellent “Quenching” event was unexpected and it has beenrecommended that further investigation into this event be conducted

ACES-II System Operation

ACES-II Ejection SeatF-16 Thunderbird Ejection

14 Sep 03

Cockpit Video

Pilot was not seriously injured

ACES–II System Operation

Video of CKU-5C/A Test – F-15, 600KEAS, HMTF – 10 Jul 04

ACES-II System Test Operation

CKU-5C/ARocket Catapult

Test – HMTF

18 June 2009

ACES-II System Test Operation

CKU-5C/ARocket Catapult

Test – HMTF

18 June 2009

ACES-II System Components

ACES-II Ejection Seat

A - AdvancedC - ConceptE - EjectionS - Seat

IHDIV, NSWCmanufactured

IHDIV, NSWCmanufactured

ACES-II Ejection Seat currently in use on USAF A-10, F-15, F-16, B-1, & B-2 aircraft

ACES-II System Function

ACES-II Ejection Seat CKU-5C/A Rocket Catapult

ACES-II System Function

CCU-22B/AImpulse Cartridge

Installed in the CKU-5C/A

• Gas Inlet at Breech ActuatesCCU-22B/A Impulse Cartridge

• Dual Firing Pins and Primers

• BKNO Charge

• Composite Propellant Grainproduces High Pressure

• Internal Locking Mechanismreleases Catapult Tubes

• Catapult Extends Lifting Seatfrom Cockpit

3

ACES-II System Function

• Catapult Gas Initiates Auxiliary Igniter

• BKNO and Propellant Chips inHigh Density Polyethylene Cup

• Rocket Motor Propellant Grainignites and Produces Sustaining thrust

• Catapult Booster Tube Separates andRemains in the Aircraft

3 Nozzles

Rocket ThrustExhaust

CKU-5C/A Catapult Effort

Primary Objective of the Laser Ignitability effort for theACES-II CKU-5C/A Rocket Catapult Alternative Propellent was:

• To establish the 50% Ignition Threshold and Time to First Lightvalues for each differing composite (HTPB) propellent configuration

These data points provided the system design engineers a rapid, low-costpreliminary evaluation to various differing HTPB propellent configurations

CKU-5C/A Laser IgnitabilityTest Results

Laser SpotLaser Spot

Example of CKU-5C/A Propellent“Sustained” Reaction - GO

Example of CKU-5C/A Propellent“Unsustained” Reaction – NO GO

CKU-5C/A Laser IgnitabilityTest Results

Example of CKU-5C/A Propellent – “Sustained” Combustion

CKU-5C/A Laser IgnitabilityTest Results

CKU-5 Laser Ignition

y = 7757.6x-1.0801

R2 = 0.9989

1

10

100

100 1000

Laser Power (watts/cm2)

Tim

e t

o 5

0%

Ig

nit

ion

(msec)

0020

Baseline

Pow er

(0020)Pow er

(Baseline)

Example of Typical Results of CKU-5C/A Propellent Testing

CKU-5C/A Laser IgnitabilityTest Summary

Summary: Over 10 alternative propellent formulations were evaluatedutilizing this laser ignitability methodology (800+ tests). One of these propellent batches (IHDIV S/N -0020) very nearly matched the Time to 50% Ignition performance of the older CTPB propellent

Therefore, the Sensitivity (or the 50% Ignition Threshold) and the Reactivity (Time to First Light or Ignition Delay) of this new propellentbatch very nearly matched the performance of the older CTPB propellent

Based on this data, in addition to other elements, sub-components and full-scale CKU-5C/A Rocket Catapults, utilizing the new HTPB propellentwere fabricated and tested at IHDIV, NSWC

All of these test results, both sub-component and full-scale, demonstratedthat the selected HTPB propellent was capable of achieving system requirements

Upgraded Capability

200W CO2 Laser

Test Chamber

200W CO2 Laser

Test Chamber

New Laser

NewTest Cell

Conclusions

• The IHDIV, NSWC Laser Ignition capability has successfully contributed to a series of design programs and on-going investigations

• NACES USRM double base propellents (KU and Mechanite 19)exhibited consistent laser ignitability characteristics at ambient and atlow temperature – “Quenching” effect requires additional investigation

• ACES-II CKU-5C/A Rocket Catapult, utilizing new HTPB propellent,successfully introduced into fleet

• The IHDIV, NWSC Laser Ignition capability has been upgraded and is being continually utilized to support a wide range of CAD/PADefforts