Ronald Veraar and Eelko v. Meerten (TNO)Guido Giusti (RWMS)

Flight and Terminal Ballistic Performance Demonstration of a Gun-Launched Medium Caliber Ramjet Propelled Air Defense Projectile

GMS conference, March 27-30, 2006Ramjet Projectile Performance Demonstration2

Contents

• Solid Fuel Ramjet Projectile Concept

• Ramjet Projectile Technology Development

• Ramjet Projectile Technology Demonstration Program• Programme definition• Design requirements and strategy• Projectile design• Free jet test facility and test results• Flight demonstration tests• Terminal ballistic firings• Conclusions

GMS conference, March 27-30, 2006Ramjet Projectile Performance Demonstration3

Solid Fuel RamJet (SFRJ) Projectile Concept

• No on-board oxidizer ⇒ superior propulsive performance• Applications

• Naval Fire Support, artillery (extended range & reduced time-to-target)

• Direct-hit ammunition (reduced time-to-target & increased kinetic energy)

• Technology development at TNO since 1980

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Ramjet Projectile Technology DevelopmentCooperative TNO/FOI research program (1995-2000)

Demonstration SFRJ propulsion for generic projectile through

• design

• manufacturing

• development

• flight testing

Thrust equal to drag capability demonstrated in flight tests

GMS conference, March 27-30, 2006Ramjet Projectile Performance Demonstration5

Ramjet Projectile Technology Demonstration ProgramProgram definition

Joint effort by TNO and RWMS

Goal• Demonstrate SFRJ technology for a specific application

Application • Medium calibre spin-stabilised air defence projectile• Fired from a standard gun

Approach• Design• Manufacturing• Flight testing of a technology demonstrator• Firings to obtain indication of terminal ballistic performance

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Ramjet Projectile Technology Demonstration ProgramProjectile design requirements & strategy• Requirements

• Total projectile length ≤ 179 mm• Projectile launch mass ≤ 0.375 kg• Acceleration load ~70000 g• Spin rate at launch ~80000 rpm• Propelled flight range ~3 km (~constant flight velocity)

• Design strategy• Geometric projectile design based on aero-thermodynamics• Mechanical design using geometric design as input• Perform experiments to verify different aspects of projectile

design• Iterate projectile design until requirements are satisfied

• Challenges• Extreme interaction between aerodynamic & mechanical design• Aero-heating of intake and gas dynamic heating of nozzle

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Ramjet Projectile Technology Demonstration ProgramAero-thermodynamic projectile design

• Air intake design based on engineering design rules

• CFD calculations by CFS Engineering SA using NSMB code• Calculation of complete internal flow field of projectile

• Projectile flight performance prediction• RP5 = Engineering code modelling subsystem performance

and their interaction• Optimize projectile configuration

GMS conference, March 27-30, 2006Ramjet Projectile Performance Demonstration8

Ramjet Projectile Technology Demonstration ProgramMechanical projectile design

• Mechanical design based on engineering design rules

• Verification of structural integrity• Projectile structure by gun

firings• Fuel by tensile tests and

bonding tests• Fuel grain by gun firings

GMS conference, March 27-30, 2006Ramjet Projectile Performance Demonstration9

Ramjet Projectile Technology Demonstration ProgramFree jet test facility

• Following ignition problems encountered in TNO/FOI flight tests• To enable on-ground verification of intake performance and

projectile functioning• Free jet Mach numbers: 3.25 and 4.0• Fixed projectile as well as spinning set-up available

GSS Air heater Free jet nozzle Projectile set-up -

GMS conference, March 27-30, 2006Ramjet Projectile Performance Demonstration10

Ramjet Projectile Technology Demonstration Program Free jet aerodynamic heating tests• Aluminium nose cone• Schlieren video

• Projectile intake• Thermo-graphic image (top)• Schlieren image (bottom)

Material other than Aluminium is required for Mach 4 SL flight

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Ramjet Projectile Technology Demonstration Program Free jet intake performance verification tests (1/2)• Fixed nozzle throat areas• Pressure measured at 4 locations

along combustor wall• CFD predictions performed by

CFS Engineering SA

0.00

0.05

0.10

0.15

0.20

0.25

0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14x-coordinate along combustor wall [m]

Free

str

eam

tota

l to

com

bust

or w

all p

ress

ure

ratio

[-]

CFD Dt=13.0mmExp. Dt=13.0mmCFD Dt=13.5mmExp. Dt=13.5mmCFD Dt=14.0mmExp. Dt=14.0mm Good agreement

with CFD predictions

GMS conference, March 27-30, 2006Ramjet Projectile Performance Demonstration12

Ramjet Projectile Technology Demonstration Program Free jet intake performance verification tests (2/2)

• Variable nozzle throat area• Good agreement with fixed nozzle

results

0.00

0.05

0.10

0.15

0.20

0.25

10 11 12 13 14

Equivalent throat diameter [mm]

Free

str

eam

tota

l to

com

bust

or w

all p

ress

ure

ratio

[-]

F020128-02Dt=13.0 mmDt=13.5 mmDt=14.0 mm

critical

sub-critical super-critical

Intake performance verification in one experiment

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Ramjet Projectile Technology Demonstration Program Free jet projectile performance verification tests

• Pressure measured at 1 location• Fast auto-ignition• Stable and efficient combustion

until fuel burn-out

Proper functioning complete projectile demonstrated0.15

0.25

0.35

0.45

0.55

0.65

0.75

0.85

0.95

1.05

1.15

1.25

1.35

23.00 23.50 24.00 24.50 25.00 25.50 26.00 26.50 27.00 27.50 28.00 28.50 29.00

Time (s)

Pres

sure

(MPa

)

F 021031-03Ch39

air heater ignition

full ramjet ignition

ramjet burn-outair heater termination

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Ramjet Projectile Technology Demonstration Program Flight demonstration tests

• Fast ignition• Constant flight velocity• Good reproducibility of flight

performance

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0 0.1 0.2 0.3

Time of flight [s]D

rag

coef

ficie

nt [-

]T = D @ 1400 m/s = world record !

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Ramjet Projectile Technology Demonstration Program Terminal ballistic firings (1/2)• Firings on range targets representing

the structure of a fighter aircraft

• Damage on target platesAll plates perforated

11 Aluminium plates with 2 mm thicknessSpacing between the plates 300 mmFirst plate 70 degrees NATO

GMS conference, March 27-30, 2006Ramjet Projectile Performance Demonstration16

Ramjet Projectile Technology Demonstration Program Terminal ballistic firings (2/2)• Firings on range targets representing

the structure of an armored helicopter

• Damage on target platesAll plates perforated

Spacing between the plates 700 mmFirst plate 10 mm RHA, 60 degrees NATOSecond plate 2mm Steel, 30 degrees NATOPlates 3-6: Aluminium plates with 2 mm thickness

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Ramjet Projectile Technology Demonstration Program Conclusions• Projectile design satisfies mass & length requirements

• Structural integrity verified successfully in gun firings

• On-ground free jet tests verified• Aerodynamic heating• Intake performance• Projectile functioning

• Flight demonstration tests demonstrated• Very short ignition delay• Clear capability to maintain initial flight speed of 1400 m/s

• Firings on range targets demonstrated• Excellent terminal ballistic performance

SFRJ projectile technology = ready for application