LO fundamentals

Question 1

Stealth

Answer 1

The act of proceeding secretly or imperceptibly

Stealth does NOT equal invisible

Attempts to defeat the enemy’s ability to detect, identify and engage.

Question 2

Stealthy

Answer 2

Accomplished with the intent to escape observation

Question 3

Invisible

Answer 3

Incapable of being seen

Stealth does NOT equal invisible

Question 4

Active Signature

Answer 4

All observable emissions from an aircraft
RF signals (comms, nav, radar)
Acoustic (engine noise, sonic boom)
Infrared (engine exhaust, skin temp)

Question 5

Active signature collection is countered by

Answer 5

LPI designs and/or noise suppression (added devices or intentional construction)
Shielding (near and mid IR) over hot parts and/or IR absorbing paint (far IR)

Question 6

Passive Signature

Answer 6

All reflected signals from an aircraft
Electro Optical/Visual
Em (radar)

Question 7

Passive Signature collection is countered by

Answer 7

Exhaust suppression (smoke trails) 
Glint or reflection reduction (flat paint)
Camp paint

Question 8

What is most critical signature for most aircraft?

Answer 8

RCS

Question 9

Explain why RCS is most critical signature for most aircraft

Answer 9

Provides all weather long range detection (EW)

Provides range, azimuth and velocity to the enemy receiver

Question 10

Four basic methods to make an aircraft stealth to radar energy

Answer 10

Shaping
Absorption
Cancellation
Tranparencies

*shaping most important

Question 11

Shaping

Answer 11

Reflect radar energy back in any direction other than the receiver

Question 12

Absorption

Answer 12

Utilize RAM to turn radar energy to heat

Question 13

Cancellation

Answer 13

Actively or passively reflected radar waves added together to cancel out

Question 14

Transparencies

Answer 14

Allow radar energy to pass through a material with minimal reduction in energy or change to wave characteristics

Question 15

Faceted shaping

Answer 15

Orient flat surfaces to deflect radar energy away from the threat radar

Question 16

Compound curve

Answer 16

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

Question 17

Planform alignment

Answer 17

Return radar signature in very specific directions away from the threat emitter

Question 18

Different kinds of shaping

Answer 18

Compound curve, planform alignment, faceted shaping

Question 19

E-RAM

Answer 19

Resonant di-electric

Narrowband, thick and light

Reflects the wave into a phase shifted form that cancels itself out

Question 20

RAS

Answer 20

Non resonant, large volume

Broadband, thick and light

Converts radar energy into heat which is then absorbed into the aircraft

Question 21

Mag RAM

Answer 21

Non resonant magnetic

Broadband, thin and heavy

Converts radar energy into heat which is then absorbed by the aircraft

Effective over a wide range of frequencies

Question 22

Describe how aircraft surface breaks and gaps effect total RCS

Answer 22

Reflections from surface discontinuities become worse at high frequencies and low graze angles

Question 23

Describe engine inlet design

Answer 23

Bury engine faces within serpentine intakes to force incoming radar beams to bounce,
Then coat intake with RAM or place intakes on top of aircraft

Question 24

Describe canopy design considerations

Answer 24

Match canopy shapes to fuselage form then coat with radar reflective material

Question 25

Other considerations besides engine and canopy design to minimize RCS signature

Answer 25

Minimize external antennas, access panels, sensor windows and external stores

Question 26

Objective of stealth

Answer 26

Is to increase survivability if the aircraft by reducing probably of detection and exposure by engagement threat systems

Question 27

How can HF radars counter stealth aircraft?

Answer 27

Exploits scattering from surface irregularities

Disadvantage: shorter detection ranges, suffers from atmospheric attenuation

Question 28

Discuss Bi static and Multi Static radars

Answer 28

Separate tx and rx antenna
Reduces effective of LO shaping technologies
Uses wide beam antenna and has a long scan time

Tough to synchronize

Question 29

Discuss Passive Coherent Radars

Answer 29

Processes reflections from non-cooperative surfaces
Reduces LO effectiveness
Relies on third party illuminators, these are covert and difficult to jam (broadcast or communication towers) —VHF/FM, TV, Cell phone
Azimuth and range information only

Question 30

To reduce detection range by half RCS signature must be reduced by what?

Answer 30

A factor of 16

Question 31

Radar signature

Answer 31

The measure of a target’s ability to reflect RF signals in the direction of the radar receiver