LO Principles

Question 1

Objective of stealth

Answer 1

Increase survivability by REDUCING THE PROBABILITY OF DETECTION and exposure to engagement by threat system

Question 2

Describe active signature/ examples

Answer 2

ALL THE OBSERVABLE EMISSIONS FROM AN AIRCRAFT

• RF Signals: comm, navigation, radar
• Acoustic: engine noise, prop noise
• Infrared: engine exhaust, skin temp

Question 3

Describe passive signature/examples

Answer 3

ALL THE OBSERVABLE SIGNALS FROM AN AIRCRAFT RESULTING FROM EXTERNAL ILLUMINATION

• EO/Visual
• EM (radar)

Question 4

Countering RF Active Signature Collectors:

Counter threat data collectors with ____________ designs.

Answer 4

Low Probability of Intercept (LPI)

Question 5

Acoustic Signature Reduction: _________ are the primary source of noise

Answer 5

Engines

Question 6

Radar signature is dominated by………

Answer 6

Shape

Question 7

Why is RCS the most critical signature of most aircraft?

Answer 7

Radar provides all weather, long range detection capability (early warning)

Radar provide target range, azimuth, and velocity data (target tracking)

Question 8

Stealth is enhanced by …. (3)

Answer 8

• Forcing Threats to use active sensors sparingly
• Using intel data to minimize onboard active and passive sensor exposure
• Use tactics that combine w/ order of battle as well as man made environment

Question 9

Define RCS

Answer 9

RADAR SIGNATURE IS EXPRESSED AS AIRCRAFT RCS.

• Amount of energy scattered back to radar by a target
• Measure of power expressed as dBsm

Question 10

Explain the factors that determine RCS size

Answer 10

Target Aircraft Factors: Azimuth, Elevation

Viewing Radar Factors: Frequency, Polarization

*** Vertically polarized waves generate significant return from wing TRAILING EDGES; Horizontally –> wing LEADING EDGES.

*** To reduce detection range by half (3 dB), the RCS must be reduced by 16

Question 11

List 4 basic methods to make an aircraft stealthy

Answer 11

SHAPING (most important)

Absorption

Cancellation

Transparencies

Question 12

Describe shaping

Answer 12

Reflect radar energy into any direction other than back to the radar site.

***AIRCRAFT SHAPING TO BOUNCE ENERGY IN SPIKES***

Question 13

Describe absorption

Answer 13

Utilize RAM to turn radar energy into heat

Question 14

Describe cancellation

Answer 14

Actively or passively reflected radar waves add together to cancel each other out

Question 15

Describe transparencies

Answer 15

Allow radar energy to pass thru the material w/ minimal reduction in energy or change in wave characteristics

Question 16

Describe faceted shaping

Answer 16

Orient flat surfaces to deflect radar energy away from threat radar

example: F117

Question 17

Describe compound curve

Answer 17

Replace straight edges with curved edges to reflect less radar energy towards threat radar

Example: B2

Question 18

Describe planform alignment

Answer 18

Return a radar signal in a very specific direction away from the radar emitter (all in the same alignment)

Example: F22

Question 19

Goals of radar absorption materials

Answer 19

• Reduce specular and multibounce reflections
• Reduce energy diffracted from trailing edges or discontinuities by absorbing energy as the wave travels along the surface

Question 20

List types of absorbers

Answer 20

• Resonent absorber (specific frequency)
• Nonresonant absorber (range of frequencies)

Question 21

Characteristics of E-RAM

Answer 21

Resonant, causes waves to cancel each other out

• Narrowband
• Thick, but light

Question 22

Characteristics of MagRAM

Answer 22

Nonresonant, coating with ferromagnetic materials

• Broadband
• Thin, but heavy

Question 23

Characteristics of large volume RAS

Answer 23

Nonresonant, radar absorbant structure

• Broadband
• Thick, but light

Question 24

How does the aircraft surface breaks and gaps affect total RCS

Answer 24

Residual reflections are caused by surface discontinuities, more significant with higher frequencies.

Reflections reduced by:

• Coating aircraft with RAM
• Filling gaps with RAM

Question 25

Engine inlet design methods used to reduce RCS

Answer 25

• Screen grids
• Buried engines
• Intakes on top

Question 26

Canopy design methods used to reduce RCS

Answer 26

• Made of radar absorbing materials with a metallic coating
• Smoothly blended into aircraft
• Shape deflects radar away

Question 27

Other considerations/methods used to reduce RCS

Answer 27

• Antennas
• Windows for sensors
• Air data sensors
• Access doors
• External stores

Question 28

List 4 basic systems used to counter stealth

Answer 28

• Low freq radar
• High freq radar
• Bi/multi static radar
• Passive coherent radar

Question 29

2 limitations of low freq radar

Answer 29

• Few frequencies available and heavy clutter
• Poor range resolution

Question 30

2 limitations of high freq radar

Answer 30

• Short range
• Atmospheric attenuation

Question 31

2 limitations with bi/multistatic radar

Answer 31

• Synchronization
• Widebeam antenna or long scan time

Question 32

2 limitations of coherent radar

Answer 32

• Reliance on third party illuminators
• Azimuth/range only

“Listening to white noise… then aircraft comes along and disrupts the noise”

Question 33

Discuss mx practices that assure LO properties

Answer 33

• Mx tracking records
• Visual inspections
• Mechanical Verification
• Material reflective measurements
• True RCS measurements
• Diagnostic imaging
• Special Facilities

Question 34

Discuss elements that contribute to cost of stealth

Answer 34

• Cost per flying hr
• Acquisition cost
• Infrastructure cost (security, support, etc…)
• Inspection cost
• Personnel cost

Question 35

What is the value of stealth

Answer 35

• provides a method of breaking the kill chain

GREATER SURVIVABILITY EQUALS REDUCED RISK OF KILL CHAIN BEING COMPLETED.

Question 36

Discuss limitations of stealth

Answer 36

• Operating cost
• Limited number of assets
• Complex MSN Planning
• Lacks flexibility
• Threats