TABLE 8-6 (C). EVALUATION OF CANDIDATE DEVICES FOR NIGHT FORMATION FLIGHT

Visual Enhancement Night Vision Sensors Other Devices

Imaging Displays Perfect Sensor~c

Aircraft Designation ELP and

~

'" e Ul k 0 k

• ~ • • '"'

k • ~ 0 :; 0

'" e 0 .~

S k 0

'"

and Location RTL

ELP RTL NVG-I BNS-25 LTV FIR HIC CLL PMD HMD

Al-l bq abq bdq f/B2

hn m e e Takeoff l/B2 l/B2 l/B2 IIBl lIBl lIBO ?/ B2 0 I I

AI-2

1 1 1 •

1 1 Rendezvous ?/BI IIBO

~ AI-3 Cruise

Al-4 :JB3 :JB3 ~JB3 l'/B3

h h h eh eh Approach ?/BI ?/B2 ? I BO 0 ?

AI-5 b, be be i k k I i ek m Landing O/B3 0 0 ? IB2 0 0 0 I 0 ?/B3

A2-1 <I d f/B2

hn m j. e e Takeoff l/B2 l/B2 ?/B2 l/BI II BI IIBO j/BO 0 0, I 1

A2-2 g j Form up I/ID 11m a llBO llBO llBO

1 1 A2-3 ap pd Cruise 1/BO ?/BO ?/BO

A2-4.0 ap pd Approach llBO ?/BO ?/BO

A2-4. I e , e Ig h h h eh eh Approach O/B3 O/B3 O/B3 ? I B3 ?/BI ? I Bl 71 BO 0 ?

A2-5 ~ ~ ~ ~ i k k I m i .k Landing ? IB2 0 0 0 I 0 ?'/ B3

*Imaging displays were evaluated individually by assuming they had perfEfct sensor inputs.

NOTES: a)

b)

e)

d)

.)

I)

,)

h)

I)

j)

k)

m)

n)

Visual enhancement of leadshipe' signature ($Al) provides angle-off reference for follower.

Helicopter is less vulnerable to ground fire than baseline case with navigation lights dim. (LND)

Candidate device does not illuminate the ground immediatElly beneath the helicopter during landing. Present navigation lights provide some downward illumination to indicate proximity to the ground.

Leaders' rotor tip light provideF.l follower with immediate indication of cycical control corrections, plus stationkeeping reference for relative altitude,and range cues.

Candidate imaging displays considered singlY are assumed to have ideal sensor inputs. Partial mirrors have only about 30 percent transmission, and degrade baseline visual capabilities.

Resolution is limiting.

Serious interference from own-ship instrument panel lights. (LID)

Azimuth coverage inadequate to sense horizon to the side ($HS) for attitude control.

Elevation coverage is limiting.

Azimuth coverage may be inadequate for stationkeeping in echelon formation.

No stereo sensor for estimating height during landing.

Covert landing lights are only active during the last missi()n segment, and are only useful with image intensifier sensors, Sensor dynamic range limitation will tend to I'black oot ll the horizon and imagery at low illumination levels. Areas illuminated too intensely may Ilwhite out ll •

Horizon indicator concept is the same as the baseline case, except the pilot does not have to monitor attitude and heading instruments, and can spend full time looking outside the cabin.

p) Leadship reference system is incomplete.

q) Pilot of lead helicopter receives same signals as for the baseline case (see Table 8-4) single helicopter.

196

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Entry in Table 8 -6

h o

abp ? / BO

Explanation of Evaluation Code

Postulated add-on system does not satisfy basic requirements for this segment, because azimuth coverage is inadequate to sense horizion to the side for attitude control.

Postulated add-on system mayor may not satisfy requirements for this segment at illumination level BO. Visual enhancement of leadship signa­ture provides reference for angle-off. Helicopter is less vulnerable to ground fire than baseline. Leadship reference system is incomplete.

Notice that the evaluation decision is basically either "0", "1", or "?". The additional notes explain the key limitations and establish light level conditions.

(U) The individual evaluation of each candidate device will now be dis­cussed in detail starting with EL panels.

Visual Enhancement Devices

El Panels (ELP)

(U) For purposes of individual evaluation it is assumed that electro­luminescent panels with overlays (ELP) are used throughout the night assault mission instead of the baseline navigation or running lights. This assumption highlights the unique capabilities and limitations of the El Panels.

(U) The entries in the isecond column of Table 8-6 show the ELP evaluation for the single (or lead) ship and for the formation follower during each seg­ment of the night as sault mis sion.

(U) The ELPs on the leadship enhance its visual signature and provide good angle-off cues for stationkeeping in trail or echelon formations. The area lighting tends to minimize vertigo encountered by stationkeeping pilots viewing conventional running/ navigation lights.

(U) The visual detection range for rendevouz is marginal on nights with full moonlight when the E LPs are on "bright". (See Section 7. )

(U) Considered individually, the ELP is marginal for the cruise and approach segments, and not satisfactory for landing. During cruise on nights without a horizion the leadship vertical reference system and maneuver cues are not satisfactory. During landing the ELPs do not illuminate the ground beneath the helicopter as do the present navigation and running lights. This makes height estimation difficult for single helicopters and forma-tion followers.

197

(U) EL panels with overlays are much more difficult to detect from the ground than the existing navigation lights. Deficiencies noted in 1969 Fort Rucker test (Reference 97) have since been corrected by improving the over­lays (see Figure 5-3) and adding an on/off switch for all EL panels on both side s of the helicopter so that they can be turned off during the final approach.

(U) In summary, the ELPs offer additional oper.ational capabilities over that afforded by the baseline UH-l lighting system for night formation flight. However, the ELPs by themselves are not suitable for landing because they do not provide a reflection to determine proximity to the ground.

Rotor Tip Lights (RTL)

(U) For individual evaluation purposes it is assumed that rotor tip lights (RTLs) are used instead of the baseline navigation and running lights. This assumption tends to emphasize the unique capabilities and limitations of RTLs.

(U) Entries in the third column of Table 8-6 show the evaluation for the single (lead-ship) and for the stationkeeping helicopter during each segment of the night assault mission.

(U) The R TLs form a "halo" that can be seen from above or below. The circular light ring provides the stationkeeping helicopter with an improved signature and lead-ship reference system that is particularly effective for determining relative elevation, and for detecting cyclical control movements made by the pilot of the lead-ship.

(U) Tests (Reference 98) with RTL configurations similar to that described in Section 5 which effectively cut off all direct illumination below the plane of the rotor disk indicate:

1) Rendezvous can be accomplished at distances of 0.5 mile or less.

2) The lights are visible to a ground observer only during the approach when the UH-l is below 500 feet, with an airspeed greater than 80 knots.

The detection range for rendezvous is considered inadequate. With the beam patterns described in Section 5 the RTLs could be seen from the ground when the helicopter was 100 feet up, especially if banks or decelerations were made (Reference 97). The visual detection range on the RTLs is, therefore, less than for existing navigation and running lights on dim.

(U) The RTLs are particularly useful for cruise when there is no horiz[lll, and for the approach segment.

(U) RTLs alone are not satisfactory for landing without additional illumi­nation, because they do not illuminate the ground immediately beneath the helicopter as do the present navigation lights.

198

____ . ..1-__

(U) Although not adequate visual enhancement for rendevouz and landing, the RTLs are considered the single most valuable visual enhancement device for stationkeeping during night formation flight.

Direct View Displays

(U) For the purpose of evaluating the unique capabilities and limitations of direct view displays it will be assumed that:

1) A "perfect sensor" provides imagery input signals to the display.

2) The pilot continuously watches the display and its general sur­roundings throughout each segment of the night assault mission.

(U) The first assumption ensures that the display is not limited by imperfect sensor inputs; the second assumption makes it mandatory for the pilot to watch the display, (i. e., the pilot cannot discard a helment-mounted display, nor avoid watching a forward-looking display during landing).

Partial Mirror Display (PMD)

(U) The fixed forward coverage of the parttal mirror display (PMD), coupled with its relatively small field of view (30 degrees azimuth, 20 degrees elevation) make it useless for stationkeeping in echelon formations and for looking downward during landing. The brightness of the projected display may make ordinary downward viewing more difficult during the final landing, and require more light than the baseline system.

(U) The partial mirror has only about 30 percent transmission and degrades the baseline in the forward sector when sensor inputs are below baseline visual capabilities.

(U) The relatively narrow fixed field of view makes it difficult to sense the horizon to the side for attitude control during the final approach - - even with the assumed "perfect sensor".

Helmet Mounted Display (HMD)

(U) The helmet-mounted display (HMD) is evaluated as an add-on to the baseline UH-l with "perfect sensor" inputs assumed.

(U) The column "HMD" in Table 8 -6 shows the resultant evaluation for each segment of the night assault mission for a single helicopter (or leader­ship) and for' a formation follower.

(U) The limited field-oi-view currently available in an HMD (40 degree maximum) is a serious limitation even with the assumed "periect sensor" and sensor pointing by pilot head motion.

199

--~----- -~~-----.

8BNfl8ENTlAt

(U) Interview results suggest pilots try to keep their heads stationary during current night mis sions to minimize vertigo problems. Howeve r, the present 40-degree field of view is clearly inadequate for landing without additional coverage from head motions.

(U) A HMD with a 60-degree field of view is feasible but would be heavier and somewhat larger than the candidate device described inSection 5.

(U) Further testing of HMDs is necessary to establish the basic require­ments for stereo altitude cues and the minimum safe field of view for land­ing. The HMD provides a unique capability for sensor pointing during the critical approach and landing segments. However, additional testing and simulation are necessary to determine pilot performance with such equipment.

Night Vision Sensors (0.4 to 1. 3 microns)

Night Vision Goggles (NVG-·l)

(U) This evaluation of night vision goggles is based on the specified':' performance of advanced production goggles (NVG-l, Figures 7-22 and 7-24). It is assumed that the pilot wears the night vision goggles throughout the mission, and that the copilot keeps the instrument panel lights on dim to monitor the instruments without goggles.

(C) Figure 7-22 shows that for the critical targets (e. g., LZ requirement for 2 to 4 mr resolution with 0.3 contrast, CP requirement for 2 to 4 mr resolution with 1. 0 contrast) the goggles may be a marginal improvement over the unaided eye. However, amplified interference from windshield glare could outweigh the marginal advantage, particularly during the approach and landing segments, as indicated in Table 8-6.

(U) Navigation lights on the lead aircraft may provide enough additional illumination for pilots of follower aircraft to land using goggles. However, this is only a possibility without further testing.

(C) Instrument and warning light reflections off the windshield introduce serious interference. However, light shields and flat black paint might reduce this to a tolerable level.

(C) Poor angular resolution may make the threshold for detecting closure rate dangerously high for stationkeeping, particularly if the large rotor cHam­eter is not visible.

,~

Performance based on measurements of presently available 18 mm micro-channel tubes (NVG-2, Figure 7-23) is clearly inferior to the eye in the critical 2 to 4 mr region.

200

, CDN~lgENJIAL

e8NFIBENfiAl

(C) Considered individually (with no auxiliary illumination), the night vision goggles offer only marginal improvements for single helicopters or formation leaders. Under full moonlight conditions, the goggle resolution is inferior to the dark adapted eye. Under less than full moonlight the goggle re solution is marginal for identifying rende zvous points, 'and enroute che ck­points. Interference from interior instrument lights (required for copilot monitoring of the instruments) is potentially serious. Because of these ' inherent limitations, the night vision goggles are considered marginal for formation leaders or singles during the critical approach and landing segments.

(C) The night vision goggles may be valuable as a night vision aid for formation followers. Interference from interior instrument lights i8 still

I a problem; however, the follower does not have to recognize checkpoints, or ,landing zones at long range. The goggles improve the detection range for rendezvous, and make a blacked-out helicopter visible at longer station­keeping intervals. The goggles may be satisfactory for formation followers during the critical final approach and landing segments. However, this can not be determined without further flight testing to establish what Army heli­copter pilots can safely accomplish while wearing night vision goggles.

(C) Present LZ illumination techniques using standard aerial flares presents dynamic range problems for the second-generation night vision

, goggle s. If the ground illumination exceeds about 1 0 -2 fc, they will tend to i l1white out".

Binocular Night Scope (BNS-25 mm tube)

(C) Figures 7-28 and 7-30 show the calculated performance of the binoc­: ular night scope. This device uses a 25 mm first-generation image intensi-, fie r tube that will go into saturation wheneve r the illumination from helicopte r I navigation light, aerial flares, exceeds critical upper limit. Tests with I similar tubes (Reference 99) suggest "blooming" occurs at a range of 220 feet from any helicopte r' with running lights on.*

(U) The evaluation in Table 8-6 is for the 25 mm tube only. The previous evaluation of the 18 mm goggles applies to the BNS-18 mm device, except that instrument panel interference is eliminated.

(U) The 25 mm BNS device satisfies the resolution and requirements for quarter moon illumination levels. The field of view is adequate for station-

: keeping; however, the fixed coverage in azimuth is too restricted for echelon ,formations. Elevation and azimuth coverage may be marginal for the final I approach and landing segments.

(C) The BNS resolution is better than the unaided eye, particularly for : low contrast. However, the threshold for detecting closure rates in forma­tion may be marginal unless the lead ship has RTLs to provide a larger reference dimension and some illumination on very dark nights.

"Automatic brightness controls may be added to correct this potential problem.

201

~8NFIBENlIAL

(U) Further testing is required to reduce uncertainties concerning the minimum field-of-view and azimuth coverage required for approach and land­ing under operational conditions. Inability to train the BNS using head move­ments during the critical final approach and landing may be a deficiency.

Low Light Level Television (LTV)

(U) For the evaluation of this candidate sensor, the pilot is assumed to watch the CRT display and the adjacent instrument panel. He does not look outside the cockpit.

(U) Figures 7 -32 to 7 -35 show the calculated performance for the 45 x 60 degree wide field of view, and for the 15 x 20 degree narrow field of view.

(C) Table 8-6 summarizes the evaluation results for this device column "LTV". The narrow field of view provides excellent resolution for locating check points enroute, and for lead ships to examine the Landing zone at the beginning of their approach. However, the narrow field is too narrow for final approach. Even the assumed 60-degree wide field may be marginal, because the pilot will probably have to leave the sensor pointed in a fixed direction throughout the final approach and landing. Landing the aircraft is a full time task, without the further complications of sensor pointing and immediate interpretation of the CRT instrument panel dis pia y.

(U) Assuming the pilot does not look outside the cockpit, the candidate LTV sensor is unsuitable for landing, because it does not provide stereo viewing nor equivalent information concerning height above the ground.

(C) Considered individually, the LTV with CRT display on the instrument panel may be satisfactory for single helicopte rs on the approach segment under quarter-moon conditions. For follower aircraft, it may be suitable for the approach segment down to starlight illumination levels.

(U) The candidate device described in Section 5 lacks stereo height capability conside red essential for landing, and require s manual sensor pointing during transition. This is clearly unsatisfactory. However, future LTF with helmet mounted displays plus an auxilary altitude indicator might circumvent these current deficiencies.

Othe r Device s

Far Infrared (FIR,)

(U) The currently available far infrared sensor (FIR) (8.0 to ll. 5 microns) is outside the spectral band specified in the requirement for this study. How­ever, it offers the unique advantage of good resolution on the darkest nights with no active illumination.

202

e8WFl9~NlIAL

(C) The resolution performance of this sensor, calculated using the same method described in Appendix B, is at least equivalent to the LTV sensor at quarter-moon illumination levels.

(U) Table 8-6 implies that with the CRT display mounted on the instru­ment panel, the 60-degree azimuth field of view may not be wide enough to adequately sense attitude cues during the approach segments.

(U) Assuming that the pilot does not look outside the cockpit, the current FIR candidate is unsuitable for landing because it does not provide stereo height information.

Horizon Indicator-Concept (HIC)

(U) In Table 8-6, column "HIC" shows the evaluation for this device con­side red as an add -on to the baseline UH -1 system. The advantage of this proposed concept is that it may permit the pilot to spend full time looking outside the cockpit on dark nights when there is no visible horizon, rather than having to periodically monitor attitude and heading instruments.

(U) Because of human factor uncertainties, it is not obvious that the proposed device will function as intended. If lights around the windshiel.d are easily interpreted by the pilot (e. g., as hilltop lights which pilots now use for horizon indication on dark nights) it may provide a cheap heads-up horizon and heading reference for all helicopters.

(U) Similar horizon indications could conceiv-ably be incorporated in the partial mirror display. However, this would require additional cue gener­ators and is beyond the scope of the present study.

Covert Landings Lights (CLL)

(C) Covert landing lights (CLLs) are turned on only during the landing segment, and are useful only with image intensifier sensors. They substitute for the white navigation light mounted on the belly of the UH-l which illuminates the ground during landing (see Section 4) and possibly for landing lights:

(C) The CLLs might be used much like the present landing lights. They would be extremely difficult for an enemy ground observer to detect visually unless he had night vision goggles.

(C) The limited imaging range of image intensifier systems (about 10- 5 to 10- 2 ILl, and the even more limited dynamic display range (about 100:1) will tend to "black out" areas of low illumination and "white out" areas illumi­nated too intensely. However, some artificial illumination is necessary on dark nights to obtain intensifier resolutions of 2 to 4 milliradians.

203

fl8NflBENTlAL

GBNFI8[Nfl~

EVALUATION OF SYSTEMS CANDIDATES

(U) The previous subsection evaluated candidate devices individually as add-ons to the baseline UH -1 system for night formation flight. The logical evaluation of combinations of candidate devices as add-on systems for the baseline UH-l is now considered.

(U) Inspection of Table 8-6 shows that all individual candidate devices were evaluated in each mission segment by classifying them as: "0" -does not meet requirements, "l!! -meets requirements for segment, or 11 ?11 exact requirements for this segment are uncertain.

(U) For single helicopters (or formation leaders) there are five such entries in each column of Table 8 -6. corresponding to the five segments of the night assault mission. These five entries can be considered as a (1 x 5) column vector which describes how well the candidate device satisfies the requirements. Similarly. the six entries for formation followers is a (1 x 6) column vector describing how well the device satisfies those requirements.

(U) Promising combinations of candidate devices for single helicopters (0 r formation leade rs) are selected by finding combinations of (1 x 5) vedo rs which have no 11011 states in COITlman, and preferably no common II?I! states.

Candidate Systems

(U) Promising combinations of candidate devices for formation followers were selected by examining the (1 x 6) column vectors to find combinations which have nO "0" states in common. This method of synthesis immediately eliminates almost all of the large number of possible combinations because they have some crucial defect.

(U) Inspection of Table 8 -6 shows that RTLs and ELPs tend to compli­ment one another. The horizon indicator concept tends to improve the base­line UH-l system. Most of the candidate sensors are deficient for landing; only the NVG and the BNS provide stereo height. The CLL concept compli­ments image intensifier systems.

(C) The above cons ide rations strongly suggest the following combinations of devices as promising add-on systems for the baseline UH-l:

• System A:

• System B:

• System C:

RTU:' ELP':' HIC Formation leaders and followers

(System A)':' NVG ':' CLL Formation leaders and followers

RTL':' ELP'" (BNS-25mm)':' CLL Formation leaders and followers

(U) Tables 8-7. 8-8. and 8-9 provide the critical signal path descriptions for each of the above candidate systems.

2.04

N o en

... w

-0

'" w ..:I ... 0

w On ~ .~

til

... w ~ 0 --0 .,. ~ 0 .~

~

'" E ... 0 .,.

TABLE 8-7 (C). CRITICAL PATH DESCRIPTION OF SYSTEM A RTL * ELP * HIC

Aircraft Number Mission Segment Signals to Pilot' 5 Eyes

AI-I, $TOP " ($HIC + $HH) Takeoff

-2, $AX " $RP " $HIC Rendezvous

-3, $AX ,', $CP " $HIC Cruise

-4, $LZ " $TA * $HS Approach

-5, $TB Landing

A2-I, $AI" $HIC Takeoff

-2, Formup

-3, Cruise

-4.0, Approach

-4. I, $TA "$HS Approach

-5, $TB Landing

NOTE:

a) Only white light on underside b) Last ship has beacon c) Flares hazardous with low ceiling

Copilot's Eyes

$INS ,', $AX

$INS

(a) $INS " $AX

$INS

Active Emitters Aboard Other Illumination

R TL ," ELP " LIP B2

B2+

B2

B3 + ADF + AIdC)

and LND(a) ! RTL ,', ELP x UP B2

BO(b)

BO

! B3 + ADF + AIC(b)

and LND(a) ! --

Symbol 'rxll eliminates logical AND Symbol 11+ II elirninates logical OR

tv o 0'

~

" "0

'" " "' ~ 0

" ~ 00 ~ .~

UJ

~

v ~ 0 ~ ~

0 ... ~ 0 .~

~

'" E ~

0 ...

TABLE 8-8 (C). CRITICAL PATH DESCRIPTION OF SYSTEM B (SYSTEM A) ~, NVG * CLL

Aircraft Number Active Emitte rs Mission Segment Signals to Pilot's Eyes Copilot's Eyes Aboard

AI-I, NVG ($TOP " $HIC) $INS ':' $AX R TL '" ELP ':' LIP Takeoff

-2, NVB ($AX ':' $RP ,~ $HIC) Rendevouz

-3, NVG ($AX ':' $CP " $HIC) Cruise

-4, NVG ($LZ " $TA x $HS) Approach

-5, NVG ($TB) $INS and CLL Landing

A2-I, NVG ($AI ':' $HIC) $INS x $AX RTL ':' ELP ':' LIP Takeoff

-2, Forrnup

-3, ,

Cruise

-4.0, Approach

-4. I, NVG ($TA ':' $HS) Approach

-5, NVG ($TB) $INS and CLL - ..

Other Illumination

B2

B2

BO

B2

I LanGIng ,

I

N o ...,

H ~

""d

'" ~ ...:i H 0

~

bl, ~ .~

rJJ

H ~

~ 0 ~ ~

0 ~ ~ 0 .~

~

'" E H 0 ~

TABLE 8-9 (C). CRITICAL PATH DESCRIPTION OF SYSTEM C RTL * ELP * (BNS-25rnrn) ~, CLL

Aircraft Number, Activ.:e Emitte rs Mission Segment Signals to Pilot's Eyes Copilot's Eye s Aboard

AI-I, BNS ($TOP ':' $HH) $INS ':' $AX RTL * ELP~' LIP Takeoff

-2, BNS ($AX " $RP " $HH) Rendevouz

-3, BNS ($CP " $HH) Cruise

-4, BNS ($LZ " $TA *$HS) Approach

-5, BNS ($TB) $INS and CLL Landing

A2-1, BNS ($Al ':' $HA) $INS "$AX R TL " ELP ~, LIP

Takeoff .

-2, Forrnup

-3, Cruise

-4.0, Approach

-4. I, BNS ($TA " $HS) Approach

-5, BNS ($TB) $INS and CLL . .. Lancung

Other Illumination

Bl

I !.

~

B2 +CLL

Bl

B2 + CLL

N o 00

o

TABLE 8-10 (C). EVALUATION OF CANDIDATE SYSTEMS FOR NIGHT FORMATION FLIGHT

Aircraft System C Designation SysternA System B BNS* CLL * RTC * ELP and Location Baseline System RTL ':' ELP * HIC NVG ':' CLL ':' (System A) 25 ms

Al-l I/B2 I/B2 I/B2 I/Bl Takeoff

-2 ! Rendevouz

-3 ?I Bl Cruise

-4 I/B3 I/(B3 + flares)

J ? I Bl Azimuth field of

Approach view marginal

-5 ! ! ? IBO With CLL ?IBO With CLL Landing

A2-l I/B2 I/B2 I/B2 Azimuth field of view too Takeoff 0, 1 /B 1 slllall for echelon

-2 I/BO I/BO I/BO Rendevouz

-3 Cruise

-4. 0 l Approach

-4. 1 I/B3 I/(B3 + flares) ?/BO With eLL on Leader ?/BO Azimuth field of Approach view marginal

-5 ! ! ~I/BO With CLL ?/BO With CLL Landing

BSNFlBENTIAl

Evaluation of Candidate Systems

(U) Table 8-10 shows the evaluation of these three candidate systems.

(C) System A offers additional operational capabilities over and above that afforded by the baseline UH-l system for night formation flight. The princi­ple advantages is making formation flight much safer. The operational risks of collision and enemy ground fire are considerably reduced. Minimum light levels necessary are not significantly reduced; however, the risk of colli­sion and ve rtigo are greatly reduced.

(C) System B may provide forma tion follower capabilities down to very low light levels. However, the minimum requirements for the final approach and landing are uncertain, and further testing is required to vedfy this possibility. The limited resolution and sensitivity of the 18 mm second­generation night vision goggles offers little performance improvement in single aircraft (or formation leaders) over and above that provided by the baseline visual system. However, the CLLs could greatly reduce helicopter vulnerability to ground fire during the final approach and landing segments.

(C) System C has the potential for being a good system for formation leaders; however, the fixed field of view may not be wide enough for safe landings. The azimuth field of view is too small for stationkeeping in echelon fo rrnations. Making the device trainable in azimuth wo uld co rre ct this latte r deficiency.

209

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6HNPln£NTIAl

9. CONCLUSION AND RECOMMENDATIONS

CONCLUSIONS

(U) This 7-month study and analysis of visionics and human factor for helicopter night formation flight has:

1) Established broad requirements for candidate devices

2) Analytically evaluated the effectiveness of off-the-shelf candidate devices individually and in combination.

3) Provided essential information concerning environmental factors and operational characteristics for helicopter night formation flight operations in Southeast Asia.

(U) The following off-the-shelf candidate devices were analytically eval­uated for single UH-l helicopters and for formation followers during the takeoff, rendezvous, cruise, approach, and landing segments of a typical night assault mission:

• Electroluminescent Panel (ELP) Lights

• Rotor tip lights (R TLs)

• Partial mirror heads-up display (PMD)

• Helmet-mounted sight/display (HMD)

• Second-generation night vision goggles (NVGs)

• 18 mm and 25 mm binocular night scopes (BNSs)

• Low light level television (LTV)

• Far-infrared sensor (FIR)

• Covert landing lights (CLLs)

211

e6NFIHENTIAl

----------------

88NFIB[NflA~

(U) Section 8 summarizes the evaluation of promising combinations of the above devices. These evaluations are based on logical analysis and demon­strated performance of off-the-shelf components. In many instances real uncertainties concerning mission requirements, human factors, and acceli't­able operational risks make it impossible to co!npletely evaluate, or exactly specify, minimum requirements without further operational testing involving prototype hardware.

(U) Rotor tip lights and ELF lights are common.to all promising system combinations. These visual enhance!llent devices provide the best currently available lead-ship reference system for stationkeeping.

(U) The approach and landing segtnents of the night assault formation mission impose the most stringent requirements on lead ships and formation followers. When the lead ship begins the transition maneuver, a stationkeep­ing pilot must visually acquire the ground and thereafter use it as his primary reference system. Some of the candidate systems !lleet the require!llents identified in the study, but further testing is required to validate these requirements.

(C) The operational !lllUl!llU!llS esti!llated for Vietnam night assault formation !llissions and used throughout this study are:

• Mini!llu!ll ceiling:

• Mini!llum visibility:

• MinirnuITl illurnination:

1000 feet above ground level (330 !lleters)

Z .. 5 !lliles (4 kilometers)

full moon for visual landing without night vision aids or auxiliary illumination

It was assumed that all other command and control ship functions could be performed satisfactorily under these conditions.

(C) Real uncertainties make it_ impossible to exactly specify minimum night vision requirements without further flight tests involving Ar!llY pilots using prototype equipment under simulated operational conditions. Never­theless, on the basis of this study and analysis it is concluded that key functional requirements for night forn~ation flight are:

• Resolution of 2 to 4 milliradians in the central field of view for sensing critical cues.

• Direct view heads-up display with 60-degree field of view and flexible coverage of +10 to -60 degrees in elevation, and -60 to +90 degrees in azimuth. Head control of direct viewing during landing.

• Visual enhancement of lead helicopters to provide a complete lead-ship reference system for stationkeeping equivaLent to RTL plus ELFs.

212

e6NFlnrNfiAt L

66NflHENfikt

• Downward illumination (covert, if possible) at least equivalent to present navigation lights for landing.

• Capability for sensing height above ground during landing equivalent to pilot's visual stereo in full moonlight.

• Closure rate detection capabilities for formation followers equivalent to present visual capability versus helicopters with RTLs.

• Night vision sensors with automatic gain control and imaging ranges of at least 10- 5 to 10- 2 fL are required because of variable battlefield illumination.

• The pilot requires the information described in Table 3-16, Section 3, with minimum data rates as indicated.

• To minimize ground fire risks, visual enhancement devices should not be detectable from the ground. During the final approach, ground observers should not be able to detect the helicopters head-on at ranges greater than the range at whic h the blacked -out silhouette can be detected.

• To provide 80 percent nighttime availability the lead -ship night vision system should function down to minimum illumination levels of 10- 5 fc.

• Stationkeeping and single helicopters require heads up peripherial horizon indicators when the real horizon is not visible.

• Better windshields, scratch free with no wide posts at the 45 -degree positions, are needed. Possibly, water jets for washing windows in flight should be provided.

(U) These baseline requirements, together with the environmental and ope rational information and the simplified methods of anal ysi s pre sented in this report, provide a sound and logical basis for

1) Further detailed studies

2) Prototype device requirements

3) Design of tests to verify minimum requirements.

(U) The present study, which is restricted to off-the-shelf devices, has not considered these advanced concepts which may offer significant advantages: 1) displays which combine imagery with cues similar to those provided by the horizon indicator concept, 2) rangefinders as an alternative to binocular night vision for landing, and 3) night vision sensors and displays which provide high resolution only in the central portion of a wide field of view.

213

, 6BNFlBENTIAl

--------------

-CONFID[NTIAt

(C) Under prevailing combat conditions, pilots may need a minimum display brightness of 10- 2 fL. This may be a serious constraint for sornie image intensifier devices.

(U) This final report plus the previous Special Annex (Reference 4), entitled "Army Helicopter Night Missions in Vietnam - Pilot Interviews" provides a complete documentation of the study.

RECOMMENDATIONS

(U) These recommendations are based on the study conclusions, and reflect the broad military R&D experience and judgment of engineers whc) performed the study. Recommendations include: 1) additional work alorJig the lines of the present study; 2) recommendations for new efforts involv!ng laboratory simulation, experimental hardware for flight test; and 3) othel: r ecornrnendations.

Additional Study and Analysis

(U) Hughes recommends further study and analysis of additional prorrj.ising candidate devices, dynamic range requirements implied by current battl<J­field illumination techniques, far infrared environmental signatures and sensor performance, and requirements for approach and landing segments of the long range patrol night formation mis sion.

(U) The following promising devices that are readily available warraqt further analysis:

1) Beta self-luminescent rotor-tip lights

2) Laser range and closure indicator as an alternative to binocular vision for landing and as a stationkeeping aid

3) Candidate displays that combine night vision imagery and horizon cues, such as horizon indicator concept

4) Helmet sight/display modification required to provide 60-degree field of view and any associated penalties

5) Low light level television and far infrared sensor mod­ifications required to provide a 60-degree field of view and any as sociated penalties

214

BBNFIBENflAt

•

,

(U) Promising devices that are not currently available but warrant flfrther study include:

1) CRT displays with marginal cues similar to horizon indicato:r concept when looking ahead, and with perimeter cues analog~us to a "fisheye" lens when looking sharply downward during lam.ding"

2) Night vision system involving two sensors with different fields viewed simultaneously (e. g., 5-degree sensor and 5-degree high resolution. display for foveal viewing; 60-degree sensor and 60-degree low resolution display properly; superimposed and blanked)

(U) Additional environmental and operational analysis would:

1) Determine 8 to 12 micron signatures (e. g., statistics for eq\.dva­lent blackbody temperature differences) for helicopters and , environmental features important for helicopter night operations,

2) Determine landing zone illumination levels, and statistical variations with current battlefield illumination techniques involving air-dropped flares and artillery illuminating car­tridges. Identify other battlefield flash exposure threats, quantify them, and evaluate

3) Consider long range patrol helicopter night formation mis siop., described in the special annex pilot interview report (Refere1ce 4), because of its importance for future night operations in Southleast Asia. The requirements for approach and landing segments of the long range patrol mission may be significantly differen~ from those for the night assault mission analyzed in this repqrt.

(U) Additional performance evaluation would:

I)

2)

Analyze and evaluate current night vision candidate devices a~d displays with regard to i1naging range, dynamic range, and automatic gain control limitations under battlefield conditionq

Attempt to develop a simple fast-attack, two-phase-recovery:, automatic- gain- control rnodel to account for the expe rimenta\ facts of human dark adaption at low-light levels. Compare model with experimental data for various flash exposures on " fovea and elsewhere

"R. H. Wright, "Integrated Display/Control Concepts, " presented. at JANiAIR Meeting, HUMRRO, Fort Rucker, 19 June 1,96 9.

215

'I

Laboratory Simulation and Analysis

(U) The present study has identified and quantified the basic requirements. H.owever, some real uncertainties remain. Human factors make it impos­slbl~ to ex:act.ly specify mini;num requirements for reasonably safe flight in c~ltical.m1sslOn segm.en:s w1thout further testing. On this basis, laboraitory slmulation and analYS1s 1S recommended in parallel:

I) Devise simulation methods for varying sensor field-of-view, ~tere.o field·of-view, resolution, sensitivity, display brightness, 1mag1ng range, dynamic range

2) Simulate variable battlefield illumination and flash, and require operators to perform a second independent manual tracking task to simulate battlefield degradation effects.

3) . Verify and refine minimum requirements (coverage, field-of-iview, sampling rates, resolution) for critical segments of the night assault mission, and for similar complex manual tracking ta~ks involving visual feedback

Experimental Devices

(U) Immediate design and fabrication of these currently available devices for experimental installation in UH-I and flight test is recommended.

1 )

2)

3)

Horizon indicator concept for single aircraft and formation fliight

Laser range and closure indicator for landing and stationkeer;>ing

Modified helmet sight for flight experiments to provide record of head position versus time, and record of eye position. Provlde alternate visual field stops and lens to allow 60- to 90-degree field-of-view variation, and 0.5- to 5. O-milliradian resolutiqn variation for tests

4) Beta self-luminescent rotor-tip lights

Flight Test

(U) Hughes recommends UH-I helicopter flight tests as soon as pos sible designed to:

I) Determine operational utility of devices (1), (2)". and (4)

2) Use experimental device 3) to determine when and where pilot glances during the approach and landing (sampling zones and rates), minimum field-of-view required, and minimum accel1t­able resolution for critical segments of a simulated night assault mission,

216

, Other Recommendations

{U} The following recommendations may be of general interest and v<;tlue to the Army:

I} Prepare and include in future editions of Army Pilot's Handbook, Army Special Texts on Formation Flight, etc., accurate photo­maps of helicopter cockpit {sirnilar to Figures 6-1 and 6-3}.

2} Deterrnine if Arrny and Air Force Aviation interests in low­altitude ceiling, visibility, and lighting statistics warrant developrnent of portable autornatic equiprnent to sirnultaneou$ly rneasure and record these joint statistics at I-hour interval~ for extended periods. Data tapes could be analyzed by cornp~ter rnethod.

3} Subsequent cost comparisons which use the effectiveness evalu­ations in this report should be based on incrernental long-teI1rn production operation and rnaintenance cost estinlates {e. g., present value of total 15-year costs with 10 percent annual discount}

2.17

"

APPENDIX A. BASIC TIME-SHARE COMPUTER PROGRAM

FOR

COMPUTATION OF NIGHT HOURS AVAILABLE

(U) Figure A-I shows the flow diagram and explains the time -share computer program used to generate the results presented in Section 2. lhis appendix presents the exact listing of the computer program in the BASI¢ Programming Lauguage, and shows examples of two of the results illustrated in Section 2, different computer printout formats.

(U) A general explanation of purpose of this program, and the exact rttethod for estimating input parameters is given in Section 2. The notation for weather probabilities used there (e. g., PO, PI, 102) is also used in the following Ipro­gram li sting.

(U) Notice that each BASIC Statement is numbered (e. g., "100 DATA, .• ") and that some statements (e. g., "230 REM--HOURS FOR NIGHT FORMATION FLIGHT") are merely explanatory remarks, and are not executable.

219

( START ) i • Q

I I 5

DIM A(14), B(14), C(5), Z(5,14) LETDI=O

1 140-142 GO TO SUBROUTINE 1100 TO COMPUTE

,

I READ A(I), B(I), C(I), WW, L, M, PO, PI, P2 I MOON HOUR ANGLE

... 150-210 ~ 610-620

PRINT VNI, L

COMPUTES H

220 (FRACTION OF NIGHT

1 THE MOON IS UP)

LET V = 23.5 LET D = 18.0 ~ 630-740 LET ¢: 7r

LET CI = 0.017453 lETll"'Cl"'l lET VI ;::: Cl '" V CALCULATION OF lET Dl '" Cl '" 0 A (I) FRACTION OF

1 NIGHT LIGHT LEVEL

250-320 ABOVE MIN IMUM

COMPUTATION OF EI ~ 750-960

(SEASON ANGLE FROM WINTER SOLSTICE)

LETS=S+A(I) /14

~ 330-370 (AVERAGE VALUE OF A (I) OVER LUNAR MONTH)

LET EI = E2

~ 970

1 380 SET UP AND

GO TO SUBROUTINE MATRIX 1100 PRINTOUT

1 390 972-IOB6

"' "." ,-'"~ ~O,"" '" "'''" ;o~<" I LET A2 = AI (HOUR ANGLE, NOON-TO-SUNSED NO LET A = AVCI LAST

LET G = (1-A/90)' 12 (HRS OF DARKNESS) CASE GO TO

? 210

• 400-430 YES

PRINT M, G, ( END ) PO, PI, P2

-~ 450

1270

SUBROUTINE 1100

FOR J = I TO 5 ( ENTER ) LETBI =C(J) LETB2=3* 81 1100 LET 83 = 10 * 82 LET S = 0

COMPUTES F1

1 530-570 (HOUR ANGLE FROM WINTER SOLSTICE),

FOR 1=1 TO 14 A1 (HOUR ANGLE

LET E1 =E2+(I-o.5)' ~/4 NOON TO SUNSET)

I 5BO-600 I

1260 UNCLASSIFIED

Figure A-l. Computer Program Flow Diagram

220

S9NFlBENfiAl B(I) = MOONLIGHT ILLUMINATION _ fc x 103

for LUNAR DAY I = 1 to 14 100 DATA . 09, . 11, • 16, 122, . 35, • 5, • 8, 1. 5, 2. 3, 3. 5, 5., 7. , 10. , 15. 110DATA.00l, .1, 1., 10 MINIMUM LIGHT LEVELS REQUIRED

" FOR FORMATION FLIGHT _ fc x 10- 3 120 DATA SAIGON, 11, 0.0, .33, .80, .96 (LATITUDE, MONTH, PO, PI, Pt) 121 DATA SAIGON, 11, 8.5, .06, .41, .92 122 DATA SAIGON, 11,4.5, .21, .63, .95 130 DATA DANANG, 16, 0.0, .16, .40, .86 131 DATA DANANG, 16, 4.5, .33, .59, .96 132 DATA DANANG, 16, 8.5, .23, .53, .94 140 DIMA(l4), B(l4), C(5) 142 DIM Z( 5, 14) 150 FOR I = 1 TO 14 160 READ B(l) 170 NEXT I 180 FOR J = 1 TO 5 190 READ C(J) MINIMUM LIGHT LEVELS REQUIRED FOR FORMATION

FLIGHT - fc x 10- 3 200 NEXT J 210 READ WW, L, M. PO, PI, P2 (LATITUDE, MONTH, PO, PI, P2) 220 PPINT l'il~,J, "LAT :", L 2,~n HEM ----------f'f'UPS ':.'R iiI GFT rPfPlt;TI:c FLIGHT 2M) nc: r1 L,HITUJr::L: '1:1~ITli :i"!: LlJi~AR [1:\y - I. ~~~O LET V = ?.~.I) 260 Lf':T T) : )~. 27() PEr'1 D:iC"' DF.r,nE£<~S n~':L(-~\:I H(iiF;I'ZJnn F!/l!~ f)Arn<~;r,~~~s

2~O LST 0 : 3.1415~ 2"0 LF.T CI : 0.017Ij~3 300 LET Ll : CI*L 310 LET VI : CI*V 3'CO U:T DI : CI*D :'),~ 0 I ",'1< ,. 7 T:: I': N :'> (; 0 3~n U:T "11 : 11.7 - '1 350 8V Tr,~ ,"l~70

3()() LET ''11 = ~1 +0.,'\ 370 LET '? : "1)~ rj/(,

3("10 LET ~l : !.~

:,"fJ G?~~!F' I)on 4,)fJ LET "'~c: ,'I ~IO LET A? : Al 420 LET A = A?/rl 430 I.I':T G :(1.0-A/an.)*12. ';1.'0 P"I'IT ""''''11')1'' "lj~c; D'R"" "P(CLI't.f?)" "L'(·.'~T "'PI ,,, "r(c+'V)" l'1 r. '. "11'11'· ,.t\ .... ~i';\, '~,1,\, r 11), .' ._~) t

4 'i n PH HI T '1, r:, PO, PI, P2 II SI) Pf'l rn 1;7fJ PE'1 IfISI:1'IICS CALCULATI0 '1 prm "flA.CTI0~1 r>r TIM': LlGI'T L~:VEL If, "I( ~?O nE~ ?O I~ pnrGA~JLITY ?F N~ OVERCAST /I')() HEc~ PI IS PR08M',ILITY rr N:J flSAVY 0VCI,CAST 500 RF.'1 P(J) I:' "n~:ILI'l::T ILLIJ"H!,HI(,'N IN F['C1T-CMDUS X 1000 510 RE:1 PI IS '1I'1jr1U1" LISHT RF'lUIR[f) P!'l: PE:S0L11TW~' n: roc X IOOI}. 5~~0 pr·'H'T "r:"-C flUl[)" , "P<fJI(!C+V)", "P<f'IO", "t,1I H}lS ~l<" ~30 FOli ,I : I 1~ 5 540 LET RI : C(J) 550 LET G~ = ~.*Pl ')(;0 LET p,:') : I C\. *[ 1 ~70 I.F.T S : fJ

221

580 '0R I : I T0 14 590 REM --THE INDEX "I" IS LUNAR DAYS I T0 14 600 LET EI =E2 + <I -0.5)*0/14 610 LET D 1 : 0 620 GI1JSU8 II 00 630 LET '3 = 'I-F2 640 I' '3< (A2-A I) THEN 680 650 I' '3< 3.1416-(AI +A2) THEN 700 6.60 IF '3 < 3 .• 142 THEN 720 610 ST0P 680 LET H = 0 690 GI1J 10 750 700 LET H : ('3-(A2-AI»/(3.1416-2*A2) 710 G0 T0 750 720 LET H = 1.0 730 G0 T0 750 740 LET H :0. 750 I' 8<I) < 81 THEN 850 760 I' 8(1) < 82 THEN 870 770 I' 8(1) < 83 THEN 890 780 LET A <I) = I.O*H 790 LE TN: .09 800 If N <8 I THEN 910 810 I' N < 82 THEN 930 820 I' N < 83 THEN 950 830 LET A(I) : A(I) + I.O*(I.O-H) 840 G0 T0 970 . 850 LET A(I) : 0 860 G0 T0 790 870 LET A(I): PO*H 880 G0. 10 790 890 LET A<I) = Pl*H 900 GI1J T0 790 910 LET A(I) = A(I) + O.*(l-H) 920 GI1J T0 970 930 LET A(I) : A<I) + PO*(I-IO 940 (J0 T0 970 950 LET A(I) = A(I) + Pl*(I-H) 960 G0 T0 970 970 LE T S : S + A (l) II 4 972 Z(J,I) :A(I) 980 REM PRINT I, 990 REM PRINT X I, 1000 REM PRINT H, 1010 REM PRINT '0R

E 1 , X2,

A (I), CHECK0UT

V I , A I ,

S

222

n, ~ '2,

AS NECESSARY

• CO'IFIH~NTIAL

SI '3

'I1JR CHECKI1JT.

'.

•

•

.e9NFIHENfIAt

1020 'IEXT I 1030 l.ET ~2 = ~*P2 1040 LET S3 : S2*(0-2*A2l*12/V I 0 'i 0 PR IN T 'j I, S, S 2, S.3 1060 NEXT ,J I 06~PR I in lOG') PRInT 1070 PHI lIT 1071 PR I NT 1072 pF:un 1073 F;]H ,J:l Tn 'i I 074 PR I NT "8 I : ", 8 I 1075 PRINT 1076 PRINT "LUi,IAlI DAY", "PUJK/C+Vl", "P(010", "AV HI;S ~1(" 1077 PIHNT 107'3 F(1H I :1 I 1:1 I/! 107Q 02:r2*Z~J,ll 108003:02*(0-2*A2l*12/0 10'01 PF\INT I,'Z(J,Il, 82,03 1092 ,'JEX T I 10",3 prI r.:r 10"/1 PH I iH 10'35 PHI NT I 0~6 .'lEXT cl 10'10 rw T,) 21rJ 1100 LET 171: ATt.J<TMHEll/COS(Vlll 1110 LET SI : -ATil<TA.':(VIl*cnS(Elll II:? rJ RE'1 DECLH1ATI0t·1 f1F' THE SUN : r - ~; I IN RMlIAc'S. 1130 IF' ~I > ~/? THEn 1160 1140 IF "1 < -(In THf:r·! 1210 1150 Sf' T~ 1230 116rJ IF ~I > 3*7n Tflnl I1Q() 1171) L>:T F I : F I + n 1180 rw T::11230 IIQO LET FI = FI + 2*0 1~?()O ('H~' T~~ 1~2,7,()

12 I 0 LET F t = F I -:1 12_~? () ·'J0 T0 12,~O

1::>,..,0 U:T XI: -CSIN(Dll + SHIU;ll*SJNCLI)l/(C!'S(~;ll*cr>S(L1)) I? 40 LET X2 - X 1 /~1n( i.QOOI-X 11'2) 1:?5rJ U:T ,~1 : -HnCY2l

223

SBNflBENTIAl

.,...----'----

EBNFIHENflAl EXAMPLE OF COMPLETE OUTPUT

SA! G0N LAT = II M0NTH HRS DARK P[CLEAR] P[N0T S0LJ P[C:+V]

0 9.99768 .33 .8 .916

F'-C REOD P[0K/C+V] P [0K ] AV HRS 0K .001 I • .<:)6 9.5978 .01 .899568 .863585 8.63387 • I .467766 .449055 4.'18952 I .307802 .29549 2. <:) 5422 10 4.69533E-02 4.50752 E-02 .450649

Bl=.OOlxlO -3

LUN P.R DAY P[ 0K IC+ V] P [ f1JK 1 AV HRS 0K

1 I .96 9.5978

2 1 .96 9.5978

.3 1 .96 9.5978

4 1 .96 <:).5978

5 1 .96 9.5')78

6 1 .96 9.5')78

7 1 .96 9.5978

8 1 .96 9.5978

() 1 .<:)6 9.5978

10 1 .96 {).5978

1 1 1 .96 9.5978

12 1 .96 9.5978

13 I .96 9.5918

1 4 I .96 9.5978

Bl=.OlxlO -3

LUNAR DAY PUlK IC+VJ P[ f1JK 1 AV HRS 0K

1 .8 .768 7.67824 2 .80176 .76969 7.69514 3 .820201 .787393 7.87213 4 .838224 .804695 8.0451 I 5 .855848 .821'614 8.21426 6 .H73177 .83825 8.38059 7 .890366 .854752 8.54556

8 .907591 .871287 8.71088

9 .925022 .888021 8.87818 '10 .942797 .905085 9.04878

1 1 .960991 ; 922 552 9.22341

12 .979516 .940393 9.40178 13 .9983')2 .958456 <).58237 14 I .96 9.5978

224

: GONflO[NfIAl

-3 Bl~.lxlO

LlI\~ 1iF' ;)A Y

I 2. 3 4

I': 7

10 II 12 L~ I I,

Bl=lxlO- 3

LU~JAR ;l,W

.3

" I :) t I 12 13 I 4

-3 Bl=lOxlO

5 c " 7

" 1 [I 1 I I? L', I IJ

P[ (11< IC+ IJ]

o 2. ~n/18~: S- 03 7).~J3311 ~-()~~ (,.;'·0701 '!:-(YC .2?:~?,:t.~ .2r:'!? 71 .~G 1 'H;(; • 5;'. 7'l~ 5 • 1)25 I OR • 7t:~<:)g4 .~n/J~c,7

.2~78~rl

.'1':)1<:)5') I

P[ rl( IC+ IJ]

c o :)

o o n o .177525 • ~:()G2f,G .5711"7 • (}LI."''O)1':5 .71"305 .'tl}:J5~

I

P[(1l</C+IJ]

o o n o o o o o n o r, ()

.321"!,1J r; • .) ;r,

CQNFI9~NlIAl

r [ Vi< ]

i1

2.7f'FG2C-O.3 ,~.1 f)1)7~ ~~-O? r; • () ~, /1 7 3 ~~ ... 0?

.2<Q 001 •. ~LI7()07 .'116!J?J7 • 6()() I O~, .1;"5/,?5 • 77?7c,R .Z6t r')('1 ':)~("~t:! •.. ' c, ...

.'1f)

P [ V!( ]

o o o o n o o .17042L, .1?80:,4 • t) /P,~.3 I~

.61>:207 • 1S3'1572 .<)7~2? .Cl/S

o ()

o o o o o o o o o o

.31G8

225

~ONFIn~NTlAt

o ? • 797') r-., ;',~- D? .?)1~l)n5

• G05?,?,c, ? • I II II ()? ?~Oq07 3 .1,1)')28 'i.Ir..~ICl 5-. r:)';)!")Gf)

r;.?~)2(S:Z

7 • 725"2 .".1;17(;" <:).5?Or:;3 ~ • 5':) 78

A\I !~I?S ('){

o o (1

o ()

o o I .703[' 'i 1.')7"l~'1

5.L,['215 f).lgOGS G.S'>/'15 '1 • ">20 G.3 ~.~'")7r

o o o o ()

(1

o (1

o ()

o ()

0.IL1181 ~). I C 72 r::;

D~ ;'!A W, M01NTH o

F-C PE'lD .001

.0089

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• I I I 0

DANA/IS M0NTH ~.5

F-C f, EID .001

0089

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D A t.J {.\ n Ci :1 (.1~: T~-! <:7.~

F-C n rc~n • OO!

0089 • 0 I • 1 1 to

&otIFlBENHAl

SUMMARY OUTPUT PRINTOUT

Lll T = I(R;, DARY

10.252')

p [ C1V IC+ V]

I •

1.

• f,'l'~1S I;; • II.~ .'I!, 0 5 • 2?~5~~1S I 2 .271/~/lr~"'02

l.AT -fiRS DAR)(

9.50567

P[ 0Y/C+I/J I • 1. .?lO377 .4~?21 .?R?l 17 4 • 7 1 I; ~~ ~ I!:_ 02

V, T = PH;'; fl'lj,j' 9.:'~IFl

P [ :'1< IC'+ \I] I • 1. .7g05<',2 • /17'~;,O5 .26?JIG7 o.2~571 ~-O2

I G P[CL[~f(]

• I I)

r[~',~{1

.re) · 86 .f)n16S7 .37!>58? • 1 '13 72 5 1.C)IiO.~?I<:-02

1 IS P[CLEAR]

• 3,~

l' [ ('1< J • 'lIS .96 • 777'96? ./,IS;;'1,)7 • 2 70?,~" 1;. C;2~)71 ';-02,

I () P[CLEAFl]

.23

P[['V]

• 0:) t\ .94 .73,,747 • II II 'i'(4 IS • ~~/; 73 77 ,'.0>'857E-02

226

~NFlD[NTlAl.

r n'l'[ ~.; "ll • II

~ \1 )1 r,:s f,'\(

~.f175:?'

8.817 ('.IG?S5 Z,.g,3037 1.c)81S?5 .?O()~~

P OJ 0T sell • ') 'l

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8. 1655 (;.61 7 13 ?, .1)/:~\~2 2, .;; o:z, (,:', .:Z':';.'~ ').'!:1

P[~' rH snL] • ')3

All fl RS C'I( 8. P,2-:,:)/\ 8. 82834 6.PS11~/j 4.1f?7;';} 2.~2?)33 .2">(1)7 /,

P[C+V] • !~ r-;

1'[C+\I ) • () G

f[C'+\f) .0 1;

APPENDIX B. PERFORMANCE ANALYSIS METHODS

(U) The periorlTIance of ilTIaging systelTIs can be parsilTIoniously spe~ified in terlTIS of 1) systelTI lTIodulation transfer function, which establishes the fundalTIental resolution capability of the systelTI, and 2) signal-to-noise ~atio in a characteristic resolution elelTIent, which deterlTIines the detection, " recognition, and identification perforlTIance. This appendix outlines the I lTIethod used to apply these concepts to the task of ilTIaging sensor evalua!tion.

(U) Using these two basic concepts, the technical perforlTIance of eac'lh candidate night vision systelTI will be predicted by lTIaking the following , four- step analysis:

1) Determine or estilTIate the sensor overalllTIodulation transfer function.

2)

3)

4)

Calculate the signal-to-noise ratio in an independent output salTIple, involving both optical resolution and the observer's integration tilTIe.

Based upon the results of step 2, calculate the signal-to-noise ratio in an output salTIple of any given spatial size and relate Ithis to the probability of resolving a standard USAF three-bar tar'lget having the salTIe apparent contrast. :

Use appropriate criteria to relate the task of resolving a starydard USAF three-bar target to the tasks of detecting, recognizing,1 and identifying the real target of interest.

MODULATION TRANSFER FUNCTION

(U) The overall sine-wave lTIodulation transfer function -- or spatial frequency response -- of a linear sensor systelTI is the product of the lTI08-ulation tran sfe r functions of the cOlTIponent s taken in se rie s. Thus, the tptal lTIodulation transfer function lTIay be expressed as '

227

---------_.

where

~

Y = sine wave MTF

N = line number (lines per vertical field of view)

and the subscripts 1, 2, etc. refer to the individual portions of the system contributing to the overall MTF such as optics, image tube, electronics, output display.

(U) In analogy with the theory of electric circuits, each modulation transfer function can be described by its equivalent spatial frequency paSiS­band. This bandwidth, denoted by N e , is defined in terms of the sine wall'e mod ulation transfer function as

co

Ne = f [Y(N)]2 dN (2)

o

(U) The reciprocal of the equivalent line number for each sensor com·­ponent represent the "blur" associated with each component. If each contributing MTF has a normal (gaussian) form these reciprocal line num­bers add exactly like random errors to give the total "blur" or autocorre~a­tion width of the system's response in the form

(N)) = (N)) 1 +(N~2) 2 + (~J 3 (3)

The above relation is strictly true only if all the MTF shapes are normal. However, in the context of system evaluation, which does not require extireme accuracy, it is generally permissible to calculate component Ne by Equation Z, and use these values in Equation 3 to approximate the overall Ne of the system. Even if the overall MTF of the system is known, it may greatly simplify per­formance analysis to calculate the overall Ne by Equation Z and then appr:oxi­mate the overall MTF as the standard gaus sian form.

i( 4)

228

o

Figure B-1 shows a typical image intensifier sensor overall MTF (NVG-I) and the gaussian approximation having the same value of Ne . As can be seen, the approximation is a pretty fair fit Over most of the spatial frequency range. However, for image intensifier sensors the cutoff frequency (defined as either 2 percent or 4 percent MTF) will generally be larger than that indicated by the gaussian approximation. Unless the MTF is highly non­gaussian, the Ne is likely to be a much better indicator of sensor perform.ance than the cutoff frequency.

(U) Since, later on in the analysis, the performance of the sensor is to be expressed in terms of its ability to resolve a standard bar target rather than a sine-wave target it will be necessary to relate the sine-wave mod­ulation transfer function to the square wave (average) modulation transfer function Y{N). These two forms of the modulation transfer function are related by

(5 )

2 - 1T [- I - I - ] Y{N) =8 Y{N) -"9 Y{3N) -"25Y{N) -'" ~6 )

SIGNAL-TO-NOISE RATIO IN OUTPUT SAMPLING APERTURE

(U) Based on the work of Schade, Coltman and Anderson, and Morton (References 87, 100, 101, and 102) the signal-to-noise ratio obtained in the output sampling aperture of size alNe by olNe can be expressed (for an image intensifer or LTV systern) as

where:

= contrast at range R (inherent contrast modified by atmosphel1ic attenuation)

D = entrance pupil diameter, cm

E = scene illumination, fc

N -- equivalent line number e

NF - noise figure (generally near I)

229

1.0 ~ ~

~ w m S

0.8

,Ill ~ ~

Z 0.6 .. '" 0-

Z Q

3 0.4 => 0 0 ::;:

0.2

o 0.1 0.2 0.3 0.4 0,5 0.6

SPATIAL FREQUENCY, LP/MR UNCLASSIFIED

Figure B-1. Modulation Transfer Function Approximation

230

I,

Sc "cathode luminous sensitivity, amps/lumen

T " integration time, seconds to. 2 second for the eye)

" =, vertical field of view, milliradians

P = background reflectivity

T = transmission of optical system

Equation 7 doe s not take into account the fact that a square wave signal at a spatial frequency corresponding to Ne is subject to a modulation transfer factor of 0.55 resulting from the overall square wave response of the sy's­tern. This correction is taken care of in the next stage of the analysis.

RESOLVING THREE-BAR TARGET

(U) Consider the task of resolving a standard USAF three-bar target with the angular width of each bar being "IN milliradians. N in this case is the line number corresponding to one bar width. From the work of O. H. Schade (References 100 and 101) the signal-to-noise ratio in an ele­ment of size ("IN) x (QJN) can be related to the signal-to-noise ratio in the output sample element of size ("/N e ) (cdN e ) as

k o (8)

If the modulation transfer function is expressed in terms of the normalized linenumberx=N/N, then

e

ko = K [y{x)lx ] (9)

and the functi on

y{x) = Y (x) Ix ( 10)

IS just the ratio of signal-to-noise ratio in an element of the bar chart to the signal-to-noise ratio in the output sample element. Figure B-2 shows the function y{x) for an assumed gaussian form of the sine Wave MTF of the sensor.

(U) chart, as

Having found ko' the signal-to-noise ratio in an element of the bar' the probability of resolving the three bar chart is given by O. H. Sdhade

( 11)

231

-------------------

0

'" ..: '" ~ ..; J: '" U ::>

~ !;; w ~

M ..:

(!) (!)

~ Z :;

> ~ ~

~ 0 ~ ~ w

'" ~ '" It '" z '"

~

Z ~

10

~\ 5

:\ 1.0

= --

0.5 --

-

0.1

= --

0.05 --

0.01 o

I\..

, 0.5

~

~ ~

'\

'" '\ I I I I \

1.0 1.5 2.0 2.5

NORMALIZED LINE NUMBER, NINe

I

3.0 3.5

UNCLASSIFIED

Figure B-2. Signal-to-Noise Ratio for Three-Bar Chart/Signal-to-Noi'se Ratio in Sampling Aperture

232

where

PAlko) =d>(ko /2)

Palko) = <I>(ko '-f5/2)

<I> (x) = cumulative normal distribution function

1 =--~

(12)

( 13)

( 14)

This resolution probability is shown in Figure B-3.

DETECTING, RECOGNIZING, and IDENTIFYING REAL TARGET

(U) The preceding analysis enables us to answer the following questions concerning system performance.

1) Given a specific three-bar resolution target, with what probability can this target be resolved?

2) Given a required probability level, what resolution can be obtained against the standard three - bar target?

(U) The final stage of the analysis relates the task of resolving the the USAF three-bar target to that of detecting, recognizing, or identifyin,g real targets. The empirical relationship suggested by Johnson (Refer­ence 103) is satisfactory for the purpose of system analysis. This empirical equivalence may be summarized as follows:

• Detection is equivalent to resolving a standard USAF three-bar pattern with bar width equal to 1/3 the target minimum dimension.

• Recognition is equivalent to resolving a standard USAF three­bar target with bar width equal to 1/7 the target minimum dilllension.

• Identification is equivalent to resolving a standard USAF three­bar target with bar width equal to 1/15 the target minimum dimension.

233

,---------'--- ------.------------------~----------

1.0

0.8

- -----.."...-

>-!:: ,:

f- V ~ 0.6 ~

0 If z Q ... 0.4 :3 0 V> W

'"

0.2

f-- / V

- / -

./ V

I , I I , , o 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

SIGNAL-TO-NOISE RATIO, k o

UNCLASSIFIED

Figure B-3. Resolution Probability (Air Force Three-Bar Pattern)

234

"

The required line number to detect an object of minimum dimension L is then

N = 3<>R (15) Detect L

where <> is in milliradians, R is in km and L is in meters. In the same manner

7<>R NRecognize =-r:-

NIdentify

PRA CTICAL CALCULA TIONS

l5O'R =: --:r:-

( 16)

( 17)

(U) As an example of atypical calculation, consider the problem of determining the range at which a given target can be detected with a speci­fied probability. A flow chart of the required calculation is shown in Figure B-4, where Co is the inherent contrast of the target against the background and V is the meteorological visible range. The other parameters have been previously defined. Note that the functions ko(P) and x(y) are not expressed in closed form so that the values must be read from a graph or approximated using numerical methods.

(U) The above analytical technique has been programmed for a time­sharing digital computer. Appendix C contains a number of computer printouts showing the perforrnance of the 25 mm binocular night scope uillder various conditions as calculated by the method diagrammed in Figure B-4.

235

-------_._-----

------------,

8- SET SENSOR PARAMETERS SET TARGET AND BACKGROUND SCI 0, a, T , Ne , NF L, p., COl E ! s

SET R = I SET DESIRED PROBABILITY P

~ SET VISIBILITY COMPUTE ~ V K

0

Y COMPUTE COMPUTE COMPUTE COMPUTE -CR K Y=K/K X(y) = NINe

T IS

SET NO IRI - RI< COMPUTE COMPUTE -R=(R +RI)/2 ALLOWED RI ~,NV3a N ERROR

? YES

DETECTION RANGE END IS R

UNCLASSIFIED

Figure B -4. Detection Range Calculation Flow Diagram

23.6

APPENDIX C. SENSOR PERFORMANCE TABULATION

BASIC DEVICE CHARACTERISTICS

(U) The sensor performance characteristics presented in Section 7 of this report were calculated using the techniques described in Appendix B as programmed for a digital computer. For completeness the data used to generate the performance curves in Section 7 is given in Tables C-l through C-12. In addition, Tables C-l through C-12 include data for 50 percent probability level which was not presented in Section 7. The tables included in this portion of the appendix are listed below.

~ Detection

of Device Resolution Performance Light Sources

NVG-l C-l C-2

NVG-2 C-3 C-4

BNS-18 C-5 C-6

BNS-25 C-7 C-8

LTV-WFOV C-9 C-IO

LTV-FOV C-ll C-12

237

·--------------.

BINOCULAR NIGHT SCOPE EXAMPLE

(U) In order to illustrate in more detail the type of data that can be generated to aid in the evaluation of night sensors one particular sensor has been selected as an example -- the binocular night scope (25 mm) -- and the methods of Appendix B have been used to examine the performance of this device in the context of two specific tasks - seeing a helicopter against a variety of backgrounds and seeing an EL panel used as a visual enhance­ment device. The performance against helicopters is expressed as the range (km) atwhich the sensor can accomplish the tasks of detection, recog­nition, or identification with a specified probability - and is a function of the background and the incident illumination level. The cases presented include:

1) Clear Weather Cases

(U) Data showing detection, recognition and identification ranges against a helicopter are presented in the table numbers shown in the followi.ng chart.

Visible Background Range (km) p = O. 05 P = O. 15 P = O. 25 Sky

20 C-13 C-19 C-25 C-31 .

10 C-14 C-20 C-26 C-32

5 C-15 C-21 C-27 -

2) Overcast or Cloudy Cases

(U) Data showing detection, recogni.tion and identification ranges against a helicopter are presented in the table numbers shown in the followi.ng chart.

Visible Background Range

(km) p = O. 05 p= O. 15 p= 0.25 Sky

20 C-16 C-22 C-28 C-33

10 C-17 C-23 C-29 C-34

5 C-18 C-24 C-30 C-35

23.8

ImNflDENTlAl

(U) Data showing the detection range against E-L Panels for various transmission conditions and background luminance levels is given in Tables C-36 to C-3S. Full brightness corresponds to about 16 fl.

(U) Themode1s of clear and overcast atmospheric characteristics used in calculation of detailed performance of BNS-25 are described in Section 7, pages 135 to 139.

239

eBNFI8ENfiAl

--~---~----------------------

SENSOR: NV GOGGLES (NVG-l)

OONfiDENTIAl

TABLE C-l (C)

SEiSITIVny: .0101 " [A/LUI'IEII J APERTURE: 1.2 [CM) IPTICAL TRAIS.: .7 '1 ELD I' VI EW: Ion HlRAD) m. LIIE NIl.: 230

ANGULAR RESILUTII. IMaAD) FIR VARIIUS BACX8RIUID LEVELS paIBABtLny LEVEL: .5

CIIINTRAST BAClGaltlllD LEVEL ["-L)

I.OE"2 1.01-3 l.tI-4 1 •• Ejo5

." 3.58 '.87 17.44 50.8r .1 . 2.77 4.43 . 9.71 2C.4 .15 2.45 3." 7.13 18.28 .2 2.25 3.25 5.84 14.2l .25 2.15 3 5.07 ll.7.

.3 2.08 2.82 4.5" II.lIS .35 2.02 2.ct! 4.21 8.96 .4 1.97 2.57 3.95 8.'9 .45 . 1.93 2.48 3.74 7.41 • 5 1.89 2.41 3.58 6.87 .6 I.S3 2.28 3.32 ' •• 5 .7 1.79 2.2t 3.13 5.-tT .8 1.75 2.15 2.99 5.03

.9 1.71 2.1 2.87 4.69 I. 1.6' 2." 2.77 4.43

----

ANGULAR RESILunl"IMBADJ 'laVARIIUS BACKGRIUND LEVELS PRIBABILITY LEVEL: .95

BAeKGRIUND LEVEL r"-L) CIITRAST

1.IE-2 1.0E-3 1.'1-4 1 •• Er5

.05 5.17 12.18 33.93 "3.~2

.1 3.63 7.03 17.95 52.5

.15 3.09 5.35 12." 35.'~

.2 2.8 4.51 9.97 27.214

.25 2.CI 4.03 8.37 22.1~

.3 2.,47 3.71 7.3 18.8

.35 2." 3.48 '.'4 I C.41

.4 2.27· 3.3 5.97 14.C!'

.45 2.21 3.15 '.'3 13.2

.5 2.17 3.83 5.17 12.08

.C 2.89 2.85 4.64 10.4

.7 2.03 2.71 4.28 9.19

.8 ., 1.98 2.' 4.11 " 8.29

.f 1.94 2.51 3.8 7.59 I. 1.9 2.43 3." 7.03 ,

240

C8NflD[NllAl

I

C8NFlBENTIAl

TABLE C-2 (C)

SENSOR: NV GOGGLES (NVG-l)

APPARENT INTENSITY [CANDLES]

.025

.05

.1

.2

.4

.8 1.6

APPARENT INTENSITY [CANDLES]

.025

.05

.1

.2

.4

.8 1.6

SENSITIVI.TY: .000155 [A/LUMEN] APERTURE: 1.2 [CM] 0PTICAL TRANS. : .7 FIELD 0F VIEW: 1047 [MRAD] EQ. LINE N0. : 230

RANGE PERF0RMANCE [KM] AGAINST LIGHT S0URCES

PR0BABILITY LEVEL: .5

BACK GR "UNO LEVEL [ FT-LJ

.01 .001 .0001

.18 .57 1.64

.26 .8 2.32

.37 1.13 3.28

.52 1.6 4.64

.74 2.26 6.56 1.04 3.2 9.28 1.48 4.53 13.13

RANGE PERF0RMANCE [KM] AGAINST LIGHT S0URCES

PR"BABILITY LEVEL: .95

BACKGR0UND LEVEL [ FT-L 1

.01 .001 .0001

.18 .54 1.47

.26 .77 2.08 .• 36 1.08 2.94 .51 1.53 4.15 .73 2.17 5.87 1.03 3.06 8.3 1.45 4.33 11.74

241

80NFI8~NIIAl

.01ll001

4.:!!3 5.~8 8.46 11.96 16.91 23.92 33.83

.00001

3·43 4.$4 6.85 9.&9 13.7 19 •. 38 27.4

-----------_.

GONFISENfiAl

TABLE C-3 (C)

SENSOR: NV GOGGLES (NVG-2)'

SEISITIVITy: .0.0." [A/LUNU] APERTURE: 1.2 {CN] IPTICAL TRANS.: .1 FIELD IF VIEW: 1141 {"RAD] IQ. LIIE III.: 144

AlGULARRES.LUTUNrNRAD] FIR VARI.US SACUR.UND LEVELS Pl"'SABILlTY LEVEL: .5

C8NTRAST SACKGR8UND L!VEL(FT-LJ

I.OE-2 I.U-3 1.1!-4 I.OE-' . ., 4.17 8.15 18~a '8.:01 .1 3.84 '.69 10.89 21.leI .15 3.41 4.8' 8.31 19.146 .2 3.28 4.41 ·7.84 15.h .2' 3.14 4.11 6.31 12.i94 .3 3.'4 S.89 '.82 II .!31 .3' 2.,6 3.13 '.46 10.11' .4 2.9 3.59 5.18 ,.211 .45 2.84 3.' 4." 8.', ., 2.19 3.43 . 4.17 8.li' .s 2.71 3.31 4.48 1.2\5 .7 2." S.22 ".27 '.~9 .8 2.', 3.14 ".1 6.2!7 .9 2.55 3.07 3.95 '.~' I. 2.5. 3.01 3.84 5. ,

-ANGUt.AR RES.LUTI .. ("RAD] F8R VARIIUS BACKGR.UND LEVELS

PRIBA8ILITY LEVEL: ."

8ACKGR.UID LEVEL (FT-L] . CINTRAST

1.'E-2 1.'E-3 1.OE-4 I .',E-'.

.05 6.41 13.26 .55.11 104!.2

.1 ... 83 8.21 1,.13 '3._8

.15 4.22 '.51 13.81 U.~4

.2 3.87 '.17 H.l' 28.~2

.25 3.'2 '.27 9.5' 23.a1

.3 5.'" ".92 8."8 2.

.35 5.58 ... 66 7.12 11.~'

.4 5.5 ..... , 7." 1'·i9 ... , 3.23 ".29 6.14 14. 9 3.16

. ".15 6.41 13. , .5

.6 3.0' 3.93 ,., Il·r .1 2.98 3.1' '.53 10. 8

.• 8 2.91 3.62 '.2" 9.4 .9 2.8' 3.53 5.01 8.1 1. 2.81 3.45 4.83 8.21

242

8iJNflB[NTlA~

eOllfl8ENTlAl

TABLE C-4 (C) st"NSOR: NV GOGGLES (NVG-2)

APPARENT. INTENSITY [CANDLES)

.025

.05

.1

.2

.4

.8 1.6

APPARENT INTENSITY [CANDLES]

.025

.05

.1 .2 .4 .8 1.6

SENSITIVITY: .000155 [A/LUMEN) APERTURE: 1.2 [CM) 9PTICAL TRANS. : .7 FIELD 0F VIEW: 1047 [MRAD) EQ. LINE N0. : 144

RANGE PERF0RMANCE [KM) AGAINST LIGHT S0URCES PR0BABILITY LEVEL: .5

BACKGR9UND LEVEL [FT-L] .01 .001 .0001

.12 .36 1.08

.16 .51 1.52 .23 .72 2.15 .33 1.02 3.04 .47 1.44 4.3

.66 2.04 6.08 .93 2.88 8.6

RANGE PERF0RMANCE [KM) AGAINST LIGHT S0URCES PR0BABILITY LEVEL: .95

BACKGR0UND LEVEL CFT-L] .01 .001 .0001

.12 .35 .99

.16 .49 1.41 .23 .7 1.99 .33 .99 2.81

.46 1.4 3.98 .65 1.98 5.62

.92 2.8 7.95

243

.00001

2.93 4.14 5.86 8.29 11.72 16.58 23.44

.000011

2.47 3.5 4.95 7 9.9 14 19.8

·.~-----------. ------.-----------------~----------

-G8NfIBENfiAl

SENSOR: BNS - 18 TABLE C-5 (C)

SENSITIVITY: .000142 [A/LUMIN) APERTURE: 1.3 rCM] 8PTlCAL TRANS.: .7 PlELD ., VUW: 1047 ("RAD] Ea. LIIE II.: 264

AHULAR RES.Lun •• [MIAD) "IR VARIeus BACKGR"UID LEVELS .. PRIBABILITy LEVEL: .5

BACXGRIUND LEVEL [FT-L] CfIlfTRAST

•• 5 .1 .l5 .2 .25 .3 .55 • 4 • 45 .5 .6 .7 .8 .9 I.

I.OE-2 I.OE-3 I.OE-4 I.U-5

3.25 6.44 IC.'4 48.~' 2.49 4.08 9.18 25.311 2.19 3.33 6.', 17.~5 2.82 2." 5.45 13.5,2 1.91 2.71 4.71 11.1!6 1.85 2.54, 4.21 9.58; 1.79 2.41 3.8' 8.4, 1.15 . 2.;U 3.61 1.62 1.71 . 2.23 3.41 6.9$ 1.68 2.16 3.25 . 6.44 I.U 2." 3.01 5." 1.58 1.'6 2.84 5.0, 1.55 1.,1 2.7 4.6'1 1.52 1.86 2.5' 4.3" 1.49 1.83 2.4, 4.08i

ANGULAR RES8Lunl. UtRAD] "R VAR18US BACKGR8UID LEVELS PRIBABlLITy LEVEL: .'5

C.ITRAST BACKGR.UND LEVEt [FT-LJ

1.8E-2 1.01-3 1.0E-4 I.U-5 .05 4.8 1J.47 32.H 99.117 .1 3.3 6.' 17.13 5'.~5 .15 2.8 l.97 11." 34.~1 .2 2.52 4.J6 9.43 26.0, .25 2.3" 3.69 7.89 21.~1 .3 2.22 3.38 6.86 17.!6 .35 2.12 3.1, '.12 15 •• 4 .4 2.t" 2." 5.57 13.9: .45 1.97 2.85 5.15 12.515 .5 1.93 2.14 4.8 II .4:7 .6 1.86 2.57 4.29 9.841 .7 1.8 2.44 3.93 8.681 .8 1.16 2.34 3.67 7.81 ., 1.72 2.25 3.46 7.14' I • 1.6, 2.18 3.3 C.,

244

88NFI8ENHAl

08NFl9~NJIAl

TABLE C-6 (C) SENSOR: BNS-IS

APPARENT INTENSITY (CANDLES)

.025

.05

.1

.2

.4

.8 1.6

APPARENT INTENSITY [CANDLES)

.025

.05

.1

.2

.4

.8 1.6

SENSITIVITY: .000142 [A/LUMEN) APERTURE: 1.3 [CM) 0PTICAL TRANS. : .7 FIELD 0F VIEW: 1047 (MRAD) EQ. LINE N0. : 264

RANGE PERF0RMANCE (KM) AGAINST LIGHT S0URCES PR0BABILITY LEVEL: .5

BACKGR0UND LEVEL ( FT-L)

.01 .001 .0001

.21 .65 1.86 .3 .91 2.63 .42 1.29 3.72 .6 1.83 5.26 .85 2.59 7.44 1.2 3.66 10.52 1.69 5.17 14.88

RANGE PERF0RMANCE (KM) AGAINST LIGHT S0URCES

PR0BABILITY LEVEL: .95

BACKGR0UND LEVEL [ FT-L)

.01 .001 .0001

.21 .62 1.65

.29 .87 2.34 .42 1.23 3.3

.59 1.74 4.67

.83 2.46 6.6 1 .18 3.48 9.34 1.66 4.93 13.21

245

~NfIBENfIAl

.00001

4.73 6. ()9 9.46 13.,38 18.'92 26.76 37.85

.00001

3.8 5.3~ 7.6 10.174 15.19 21.49 30.$9

r I

88NFlBENfiAl

SENSOR: BNS-25 TABLE C-7 (C)

SnSITIVlTY: •• 00142 [A/LUMENJ APERTURE: 2.26 [C" ] IPTICAL TRA.S.: .7 FIELD ., VIEW: '42 [/IIRADl &a. LINE N •• : ~~4

AIGULAR RES'LUTI •• ["RADJ FIR VARI.US BACKGReUND LEVELS PR.BABILITY LEVEL: .5

CIITRAST BACKGReUND LEVEL [Fr-Ll

.05

.1

.15

.2

.25

.3

.35

.4

.4'

.5 .,

.7

.8

.9 1.

1.0E-2 I.OE-~ I.OE-4 l.tE-5

2.12 ~.'4 '.81 28.36 I." ·2.' 5.52 14.1, 1.47 2.Ii 4.09 10.21 1.1' 1.93 ~.37 8.01 I.~ 1.19 2.'4 6." . 1.26 1.68 2.66 5.75 1.22 1.6 2.41 5.1 J .2 1.54 2 •• U 4.62 1.11 1.4, 2.21 4.24 1.15 1.45 2.12 ~.'4 J .11 1.38 1.97 ~.4' 1.09 1.34 1.86 3.16 1.06 I .3 1.18 2.'2 1.04 1.27 1.71 2.7" 1.03 1.25 1.6' ·2.6

ANGULAR R!SeLun •• l"RAP l·"R VARnus BACtGRIUND UVELS PReBABILITy LEVEL: .95

BAC.8ReURD LEVEL [Fr-ll CIRTRAST

1.0£-2 1.("':-3 1.0.E-4 I.OE-5

.05 .'5 6.83 18.'5 57.28

.1 2.15 4.03 10.09 29.25

.15 1.84 3.09 7.1~ 1,.91

.2 1.67 2.'4 5.66 15 .. 2"

.25 1.56 2.37 4.77 12.44 .• 3 1.48 2.19 " .II! 10.~n

.35 1.41 2.06 3.16 9.23

.4 1.37 1.9« 3.4" 8 •. 23

.45 1.34 1.88 3.1, 1.45

.5 1.31 1.81 3 6.83

.6 1.27 1.1 2.11 5.9

.7 1.23 1.62 2.51 5.23

.8 1.2 1.5' 2.36 4.73

.9 1.18 I.' 2.24 4.3" I • 1.i6 1.4' 2.15 4.03

246

88N~18fNlIAl

SENSOR: BNS-2S

APPARENT INTENSITY [CANDLES]

.025

.05 • 1 .2 .4 .8 1 .6

APPARENT INTENSITY [CANDLES]

.025

.05

.1

.2

.4

.8 1 .6

bQNFIQ~NTlAl

TABLE C-8 (C)

SENSITIVITY: .000142 [AILUMEN] APERTURE: 2.26 [CM] 0PTICAL TRANS. : .7 fIELD 0f VIEW: 942 [MRAD] EQ. LINE N0. : 334

RANGE PERf0RMANCE [KM] AGAINST LIGHT S0URCES

PR0BABILITY LEVEL: .5

BACKGR0UND LEVEL [ F'T-LJ

.01 .001 .0001

.3 .92 2.68 .42 1.3 3.79 .6 1.84 5.36 .84 2.6 7.58 1 • 19 3.67 10.73 1.69 5.19 15.17 2.39 7.34 21.45

RANGE PERf0RMANCE [KM] AGAINST LIGHT S0URCES

PR0BABILITY LEVEL: .95

BACKGR0UND LEVEL [ FT-LJ

.01 .001 .0001

.29 .88 2.42 .42 1.25 3.42 .59 1.76 4.84 .83 2.49 6.84 1 • 18 3.53 9.68 1.67 4.99 13.68 2.36 7.05 19.35

247

S8NFIQENUAl

.00001

7.01 9.91 14.01 19.82 28.03 39.64 56.06

.00001

5.73 8.11 11.46 16.21 22.93 32.43 45.86