Army Aviation Digest - Oct 1979

8/12/2019 Army Aviation Digest - Oct 1979

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T HOSE OF US fortunate enough to have enjoyed a long association with Army aviation have witnessed many changes overthe years. We have seen Army aviation grow from its pre-Vietnamsupport role to the proud position it occupies in todays combatready force. We can point with pride to the ever-i ncreasing rolethat Army aviation plays in counteracting threat forces throughoutthe free world.

Today, at least symbolically , we embark on another chapter inour proud history. The new masthead which appears on the coverof this month s issue of viation Digest is designed to representArmy aviation today. This new masthead, as symbolized by thehawk, is indicative of the fighting spirit of Army aviation units andunderscores our versatility as a full-fledged member of the combined arms team. The hawk, a magnificent bird of prey that usesstrength , quickness and the element of surprise to outmaneuver Major General Merrymanits opposition, is indeed a worthy addition to the masthead of the viation Digest It symbolizes Army aviation s new role as a combat arm.

Other significant changes are occurring in the area of aviation operational concepts andcommissioned of ficer career patterns.

Today to counter the probable threat, a requirement ex ists in Europe as well as in manyother places around the world for highly mobile , lethal forces. Army aviation must playamajor role in providing this capability. To do this Army aviation units must be orga n ized sothat we use their full potential. Currently the Army is studying the establishment of anaviation brigade in its divisions. It would provide the division with a fourth maneuver brigadeheadquarters. The new organization is called the Air Cavalry Attack Brigade ACAB) andwould consist of battalion sized elements consisting of attack helicopter squadrons and acombat support aviation battalion. Operating asa full-fledged memberof the comb ined armsteam , the brigade s firepower and mobility could be critical to our success on the battlefieldof the future. An article on the ACAB will be forthcoming in a future issue.

To support Army aviation s expanding battlefield commitments, the Army Chief of Stafflast spring announced major changes which establish a new Army aviator career pattern.Designed to create long-term management policies for developing aviators under theOfficer Personnel Management System OPMS) , the changes affect branch determination,officer basic and advanced courses, initial utilization following flight school and additionalspecialty development.In the July 1979 issue of the viation Digest MAJ William B. Leonard discussed in depththe new career management program for commissioned aviators which is underway withinthe Military Personnel Center MILPERCEN). This program also was detailed by LTCGeorge A Morgan in the April 1979 issue of the Digest It is recommended that you familiarize yourself with these changes and how they may affect your aviation career. TheOPMS Corner in the viation Digesthas been carrying a continuing series on the emergingcareer management program.

This issue of viation Digest is significant in another aspect as well. It features an updateon the AH-1 S Cobra with a lead article by the project manager, COL Jay W. Pershing page2). In addition, the three-part AH-1 S series which appeared in the January, February andMarch 1978 issues has been updated and begins on page 25. The viation Digest hasreceived requests for thousands of reprints of these articles, and they continue to come in.

The modernized Cobra, with its improved firepower and mobility is keeping pace with theincreasing emphasis being placed on the role of Army aviation as a combat arm. So is theviation Digest with its new masthead. Major General James H. MerrymanCommanding GeneralU.S. Army Aviation Center and Fort RuckerFort Rucker , AL


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obra ProgramPositl R ReportColonel Jay W PershinProject Manager Cobra TS RCOMSt. Louis MO

T HE AH lS mod e rnization program has continued to progresss ince it began in 1975 . T oda y wear e about halfway th ro ug h th emode rniza tio n e ffo rt a nd a re fielding th e new productio n Enhanc edCobra Armam e nt Syste m (ECAS )Co bra with th e 20 mm ca nn o n andunive rsal turre t.

Th e c ha rt o n page 4 pro vid esan o ve rview o f th e to ta l mod e rni zation effo rt. The de livery schedulesfo r th e diffe re n t AH - l S mo de ls ar esh own in each blo ck. Ne w produ ctio n de liveries ar e sh own in ste p I(production S , step 2 (up-gun S)a nd step 3 (fully mo de rni ze d S).Modification of th e exi sting AH -1G fl ee t is shown in th e to p bloc k(mo d S) and st ep 3 (AH IG to full ymod e rnized S).

Maj o r m odifi cat io ns be in g ad d e d to th e AH IS in th e epara tes te ps in c lud e th e tu b e-la un c h-

d . op ti ca ll y- tr ac ked. wire -g u id e d(TOW ) miss ile sy te m, he lme t sightsu bsys te m , up rated e ng in e a ndpowe rt ra in, improved avio nics a nda ircraft sur viva bility equipment ,universal turre t with a 20 mm can no n, rocket manage ment sub systema nd fir e co nt rol sys te m. De ta ils o fth ese impro ve ments a re di sc ussedin the th ree mode rni zed Co bra a rti cles at the ce nt er o f this iss ue .Co mpletio n of th e th ree s te ps o fth e recycle pr og ram shown a t th elowe r right o f th e chart will prov id eth e Army with a standa rdized Co bra fl ee t with increased fire powe rand pe rfo rmance . Fie lding o f th e98 a irc ra ft show n in ste p 2 o f th ec ha rt has bee n acco mplished a t Ft.Hood . TX : Ft. Campbe ll, KY : Ft.Bli ss, TX ; a nd Ft. Bragg, NC .Fie ldin g o f th e re ma ining airc ra ft in ste p 2 began a t Ft. Carson ,CO las t mo nth. As a matte r o f inte res t, th a irc ra ft assigned to Ft.Bliss were th e first to be equippedwith th e new imp ro ved main ro to rblade . It is pla nn ed th a t a ll future

ne w pro du c tio n a irc ra ft w ill haveth e ne w blades in sta lled .As th e new pr odu c tio n AH - lSCobras are fi e lded , th e rema iningAH l G fl ee t is be ing ph ased intoth e Be ll H elico pte r Amarillo, TXfac ili ty fo r modificati o n to th e full ymod e rni ze d AH IS a irc raft. Afte rnex t mo n th all a ircraft de live redfro m th e new pr odu c tio n line inFt. Wo rth , TX a nd th e modificatio n lin e in Am a rillo will be in th efull y mod e rnized co nfig uratio n.

Op e rati o nal readin ess ra tes fo rth e Co bra / TOW ai rc raft ha ve me to r exceed ed th e Depa rtm ent o f th eArmy s tandard o f 70 pe rc e nt sinceits initial fie lding in 1975 . The ove rall Co bra flee t (AH I G and AHIS ) ope ratio na l readiness (OR ) ra tewa s 78 pe rce n t in Fe brua ry 1979 .This wa s th e hi ghes t OR ra te eve rachiev ed by th e AH I flee t.

The co n trac to rs tes tin g o f th efully mo d e rni zed AH IS with th enew fir e co ntro l sub sys te m wasco mple ted las t June . T es t res ult sto da te o n th e full y moderni z d


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Cobra have been extremely en couraging, surpassing our expectations, particularly the deadly accuracy being achieved with the 20

mm cannon. Development testingDT) began in July with operational

testing OT) scheduled to ollowthis month. Completion of DT T

testing s set for next month, whenit s planned for the irst ully modernized AH-lS to be delivered tothe Army. Monthly meetings with


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1 1975 1 1976 1 1977 1978 1979 1980 1981 1982 1983 1984 198590aircraft MODII I

. kill t i j EP 1i r ~ ~ f t EI",iii ST P 2I I I

a i r ~ ~ a f t W STEP 3I I IaiW 1ft

1975 1976 1977 1978 1979U. S. Arm y Missile Co mm a nd , .S.

rm y Arm a me nt Readin ess Co mma nd , .S. Army Communica tio nsa nd El ec tr o nics Ma te rie l Readin ss Co mmand , . . Ar m y T ro o pSupp o rt a nd A via ti o n Mat rie lR ea din ess Co mm a nd a nd Be llHe lico pte r a re be ing he ld to ass ur ea ll necessa ry ac t io ns a re take n too bta in a tim e ly ma te ri e l re lease o fth e full y mode rnized AH-IS.

Wh e n th e full y mode rni ze d Co bra is first fi e lded th e lase r ra ngefind e r and airbo rn e lase r trac ke r(AL T ) will no t be ins tall ed. Th elase r exp e ri ence d so me tec hnica lpr o bl ms, whic h , coupl ed with in c reased producti o n leadtim e, haveca used a s lippage un t il nex t Ju ly.Aircraft fi Id ed witho ut th e lase rra ngefinde r will be ret ro fitt d inth e fi e ld by exc ha nging s ta ndardTOW missile ub y te m te lesco pics ight units (TS ) with lase r ra ngefinde r equipped TS U. Th e dec isio nto d e fe r insta lla tio n o f th e ALT isr la ted to th e availa bility o f a fie lded lase r desig na to r. Ea c h ai rc ra ftwill be equipped with co mple teprov isio n so th e ALT ca n be installed in the fie ld at the appropria tetime .

Future AU-l Configurations.La st August a me mo randum o f und e rs tanding (MO ) o n AH-l co nfigur a tio n wa s es tablished a mo ng

4

AIf. GTORlUY MODERNIZED IIa i ~ r ~ f t ddt i.i.I

' 100 98 II rnm

fiR ISlfoderniz ltionProgram1980 1981 1982 1983 1 1984 1 1985 ch dule

th e co mm a nding g ne ra l o f theAvia tio n Ce nte r, Armo r Ce nt er a ndTSARCOM . The MO es ta blisheth e AH-l co nfigur at io n a nd assur e th a t future c ha nges to th eAH - l will e nh a nce th e co m bat e ffec tive nes o f th e Cob ra wea po nsys te m. All th ree princ ipa ls mu s tag r e to a ny future co nfig ur a tio nc hanges . As a res ul t o f th e ag ree ment , ac tio n has be en initia ted tote rmin a te the CON S nav iga tio npac kage, prox imity wa rning r ce ive r a nd the M-130 c ha ff d ispe nse r.Th e 1978 Arm y Av ia tio n yste ms Prog ra m Rev iew highlightedso m o p ra ti o nal limita tio ns o f a t-tac k he lico pte rs fo r th e futur e battl fie ld . Fo r th e Co br a, th e lac k o fa ni ght ca pa bility is an o p ra tio na llimita tio n. In a n e ffo rt to pr ov ide alimited night ca pa bility, th e Co braprojec t m anag r in co njunc tio n withNi ght Visio n Labo ra to ri es has initia ted a feasibility de mo ns tratio npr og ram fo r a FLIR (fo rwa rd loo k-ing infra red rad a r ) Au g me nt e dCo bra TOW Sight (FACT . Th eF T S y tem will prov id e th e co p ilo t gunne r with an improv d ca pability to acquire and engage ta rge tsduring pe riods o f poo r da ylight visib il ity (dawn, du sk , smo ke , haze,e tc .) a nd a t night.

The feas ibility d e mo ns tr a ti o npr og ra m is o ngo ing w ith th e o bj ec-

ti ve to de mo ns tra te th e improvedAH-l adve rse wea th e r targe t acquisitio n ca pa bilities a nd to fo rm abas is fo r a required o pera tio na lca pab ility c ha ng in support o f ad ve lo pm e nt pr og ra m fo r FA CTS .Co nt rac to r tests co nduc ted in A ug-u t we re comple te ly suc cessfu l. FiveT W miss iles we re fired and a llmis iles hit th ta rge t.Th e Co br a TOW pr og ram i avita l o ne fo r th e de fe nse o f o urco untry. Th e Co bra tea m is wo rking ha rd to pr ov ide th e bes t attac khe lico pt e r wea po n sys te m for o urfighting fo rce now

COL Pershing entered the Army in 954after being graduated from Purdue Uni-versity in West Lafayette, IN. He earned amaster's degree in Business Administra-tion from Michigan State University, EastLansing, and is a graduate of the ArmyWar College

U .S. ARMY AVIATION DIGEST


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Helmet Mounted Sight

Fire Control Computer

Figure 1

~ o e r n i z e obraFire ontrol System

H MODERNIZED AH-1S1.Cobra is the result of a seriesof evolutionary changes responding to a changing battlefieldenvironment . When the AH-1Gwas introduced to combat in 1967the target array primarily wastrucks, troops and sampans . TheAH-1G ' rockets and turreted7.62 mm miniguns could be usedat close ranges and at altitudesof 1,000 to 2,000 feet with goodeff ct and relative immunity fromthe unsophisticated air defensecapabilities of the enemy. A simpleairspeed based jump correctionand eyeball estimated rangecorrection were sufficient forgetting turreted gunfire near theOCTOBER 1979

George L CohillManager Systems Integration

ell Helicopter Te xtronFt. Worth TX

short range targets and the firewas then walked onto the target.For rocket delivery a manuallypreset combining sight was usedalong with the tactic of making ashallow dive at the target. These

canned maneuvers were practiced until some of the old handsbecame proficient at deliveringrockets under a particular set ofconditions.The battlefield of today, domi-

nated by armor accompanied bysophisticated air defense capabilities, requires a gunship able todeliver accurate fire on the firstburst at standoff ranges whileflying nap-of-the-earth. Themodernized Cobra with its TOWmissile system, 20 mm turretedgun, remote set fuzing multifunction rocket warheads, rocketmanagement system, and integrated gun and rocket fire control system (figure 1 is equippedto respond to the demands ofthis new, more sophisticatedbattlefield environment . Theaddition of the TOW missilesystem (figure 2 to the AH 1 Gin 1972 gave the capability to

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deal with the armor threat of themodern battlefield.In the spring of 1978 theuniversal turret subsystem withits 20 mm automatic cannon wasqualified on the AH-1S see page34, figure 3, this issue). As partof the same program the additionof the rocket management subsystem page 38, figure 7 givesthe AH-1S pilot the capability tomanage the inventory of asmany as 76 rockets of fivedifferent types to select and firethem at various rates and toremotely set the RC fuzingsystem in the rockets.The stabilized telescopic sightunit from the TOW missilesystem can be used to aim theturreted 20 mm gun. TheAH -1S,therefore, had all of the elementsfor aiming and firing the 20 mmcannon at standoff ranges, butdid not have a fire controlsystem to provide the necessarylead angle and super elevationcorrections to make the gunfiresystem adequately accurate atthose ranges. The same was trueof the rocket system. The man-

ual techniques used in Vietnamwere totally inadequate to handle the problem of firing rocketsfrom nap-of-the-earth, at hoverand low air speeds, and out toranges of 6,000 meters withsufficient accuracy to make theweapon effective.Studies conducted at BellHelicopter Textron and testsconducted by the Army hadshown that gunfire and rocketfire accuracy could be improvedby factors of two to five by theaddition of a full solution firecontrol system. During the fallof 1976 BHT performed detailedsystems studies and prepared aset of specifications for a laserrangefinder, an omnidirectionalair data system a head-updisplay and a digital fire controlcomputer. In the spring of 1977Bell conducted a competitionand source selection for the fourmajor elements of the fire controlsubsystem. These major subsystems were integrated by BHTwith the TOW missile systemthe XM-128 helmet sight subsystem the AN / ASN-128 light-

FigureTOW Missile System Components

AADSADSBHTCRTDCEPUFCCFURHUDHUDS

~ l TLAILOSmmmradMTBFRCRMSTOWTSUTTL-MSIVVW

Glossaryairspeed and direction sensorair data subsystemBell Helicopter Textroncathode ray tubedirect currentelectronics processor unitfire control computerforward looking infraredhead-up displayhead-up display systemhertzlaser augmented airborneTOWlow airspeed indicatorline-of-sightmillimetermilliradiansmean time between failurerecent capacitancerocket management systemtube-Iaunched opticallytracked wire-guidedtelescopic sight unittransient transient logicmedium scale integrationyoltYoltamperewatt

weight doppler navigation subsystem the airborne lasertracker the rocket managementsubsystem the universal turretsubsystem and several otheronboard subsystems to provide afull solution fire control subsystem for the AH-1S. A functionalblock diagram of the fire controlsubsystem is shown in figure 3.In the subsequent paragraphsthe fire control system isdescribed in terms of a few of itsprimary modes of operation.Highest accuracy gunfire isachieved using the TSU fortarget acquisition and tracking.In this mode the gunner tracksthe target with the TSU andobtains accurate laser range tothe target by means of the TSUmounted laser rangefinder. Theuniversal gun turret is connectedto the TSU through the interfacecontrol unit. In the absence ofgunline commands from the firecontrol computer the gun turretpoints at the same target thatthe TSU is tracking. The fire


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control computer takes in line-ofsight angles, line-of-sight anglerates and range data from theTSU ; air data (three dimensionalairspeed, static pressure and airtemperature) from the air dataset; three dimensional aircraftground speed from the doppler;and aircraft pitch and roll angleswith respect to the local verticalfrom the vertical gyro.With the range and LOS ratedata and doppler velocity data ,the computer generates an estimate of target ground velocityand aircraft ground speed. Windspeed is computed by combiningdoppler velocities and vectorairspeed from the air data set.Air density is computed from thestatic pressure and temperaturedata.All of the preceding parameters are combined by the computer in a set of ballisticequations to compute azimuthand elevation offset angles bywhich the gun turret must bedisplaced from the line-of-sightto the target in order for thebullets to hit the target. Boresight corrections which arestored in the fire control computer are added automatically tothe azimuth and elevation offsetsto account for boresight errors.

The final azimuth and elevation offset angles are updated ata 50 Hz rate and added to gunlines displacing the gun turretfrom the TSU line-of-sight by acorresponding amount. Whenthe gunner pulls the trigger thecannon fires a burst of 20 mmrounds at a 730-shot per minuterate. The projectiles shouldintercept the target at the pointwhere the target will be when theprojectiles arrive. In the firecontrol solution the computerhas accounted for range, projectile ballistics, aircraft to targetgeometry, aircraft attitude aircraft motion, angles of attackand sideslip, wind, air densitytarget motion and weapon sys-OCTOBER 1979

TO WSTEfRING INDICATIOIlS

TELESCOPICSIGHTuN;T

R W lASER R NGE

lOS ERROR

~ ~ ~ ~ F I N E R t H_GE_

FceSTATUS

FIREeorHROle(> oPUTE_

igure

lO HIALT

Modernized obra Fire ontrol Subsystem

tem boresight error .Either crewmember can usethe helmet mounted sight todirect gunfire. In this modeaccurate LOS angle rate information is not available andmanually estimated range isused , but the fire control solution accounts for all of the othervariables listed above. The helmet mounted sight directedgunfire mode is not as accurateas the TSU directed mode, butsince the helmet sights are usedfor snap shooting at close-intargets high accuracy is notrequired.

There are two basic modes ofrocket delivery direct andindirect. In both modes the pilotuses the head-up display as theprimary sighting system. In thedirect mode the fire controlcomputer takes in range information from either the laserrangefinder or manually setrange on the rocket managementpanel; the type of rocket selectedby the pilot on the RMS panel;and collective position for down-

wash computation; in addition tothe inputs (other than LOS andLOS rate) used for gunfire.The fire control computer calculates a solution to the rocketdelivery problem and positionsthe HUD fire control reticle in

azimuth and elevation. The pilotthen maneuvers the aircraft in away such that the reticle superimposes on the target andpunches off the rockets. Basedupon the rocket and penetrationmode selected by the pilot thecomputer also computes a timeof function or a penetration delayfor the fuze.The indirect rocket deliverymode uses the TSU as the targetacquisition and tracking sensor.The HUD is used as if it were anordinary cathode ray tube typedisplay as opposed to a seethrough combining sight. Undercertain conditions such as longranges (more than 4,800 meters)it is necessary to elevate the noseof the Cobra so much that itactually interferes with thepilot s line-of-sight to the target.

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FigureHead Up Display Subsystem

aircraft for rocket firing, and tomonitor certain critical flightparameters without divertingattention from the target scene.The HUDS (figure 4 consists ofthree line replaceable units, apilots display unit called aHUD , a symbol processor unit,and a boresightable mount.The HUD is mounted on top ofthe pilots instrument panel andpresents flight, target acquisition and weapon delivery information using a CRT/opticaldisplay. An optically-coatedglass, dual combiner is used toreflect the symbology which isgenerated by the CRT into thecentral 20 degrees of the pilot sforward field of vision. The

symbology which appears in thepilot s field of view is focused atinfinity giving pilots essentialinformation that they can viewsimultaneously with the target,without constantly refocusingtheir eyes and scanning a multitude of panel instruments duringtarget attack. Weapons systems, fire control, flight statusand flight control informationare displayed, including targetacquisition reticles, aircraftboresight reference, andgunner s sighting cues. The firecontrol data displayed includesaiming and firing data forrockets and TOW missiles and isbased upon the weapon typeselected by the crew. Also displayed are engine torque, radaraltitude, magnetic heading andtarget range data information.

The symbol processor receivesand processes inputs from thefire control computer and otheraircraft sensors and generates allof the symbology which is displayed on the HUD.The boresightable mount,which becomes a permanent partof the ship after boresighting,pennits complete interchangeability of the HUD at the unitmaintenance level without theneed for reboresighting.

The head-up display subsystem is a compact, lightweight

Under these conditions thepilot cannot superimpose the firecontrol reticle on the targetwhich must be done in the directmode. The pilot , therefore,switches to the indirect modeand has the gunner track andrange on the target . The LOSand range da ta from the TSU iscombined by the computer withthe other parameters describedabove and the fire control reticleis displaced by the appropriateamount. Pilots then fly theaircraft in a way such that thefire control reticle is superimposed on the aircraft boresightreference symbol. When the twosymbols are superimposed thepilot fires the rockets whichshould strike the target whichcannot be seen from the cockpit.The indirect mode can be used atshorter ranges as well, if thecrew prefers it to the directmode.

Figure 5

As stated, four major subsystems were added to theAH-IS to provide an accuratefull solution gun and rocket firecontrol system. Each of thesesubsystems is described in moredetail below.

The head-up display subsystem presents pilots the collimated symbology they require toalign the aircraft for TOWmissile delivery, to aim the8

Air Data Subsystem


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system weighing 6 pounds. TheHUDS is constructed of modulesfor quick replacement whenmaintenance is required. Thecurrent estimated MTBF isnearly 1,500 hours.Brightness of the display canbe adjusted to be compatiblewith night vision goggles fornighttime use. The addition ofthe head-up display subsystemto the modernized Cobra, withits ability to represent instantweapon delivery and flight information, significantly enhancesthe 24-hour mission effectivenessof the Cobra weapon system.

Accurate air data is essentialfor both gun and rocket firecontrol. This information is provided to the fire control systemby the air data subsystem. TheADS is shown in figure 5. The airdata subsystem consists of threeline replaceable units: The airspeed and direction sensorAADS), the electronics processor unit EPU) and the lowairspeed indicator LAI). Eachline replaceable unit is replaceable without any adjustment toother subsystem units.

The airspeed and directionsensor is a swivelling pitot-staticprobe, which senses local airflowpitot and static pressures, theangles of that airflow relative tothe helicopter, and the freestream air temperature. Pneumatic pressure outputs and electronic signals for angles andtemperature are fed to the EPU.The EPU converts pneumaticpressure information to analogsignals through electrical forcebalance pressure transducers.These pressure signals are combined with angle and temperature data by a microprocessorbased computing unit. Outputsignals from the E PU are in theform of analog and digital formats that interface with the firecontrol computer FCC), theradar altimeter and the LAI.

The low airspeed indicator is aOCTOBER 1979

standard 3-inch indicator whichdisplays forward and lateralcomponents of airspeed up to 50knots in any direction. Digitalsignals are available to the FCCfor forward velocities up to 223knots.

Total subsystem power consumption is less than 25W fromthe aircraft 28V DC supply andless than 200 V A from theaircraft 115V 400 Hz supply forAADS anti-icing. The subsystem weighs less than 10.5pounds.The single most importantfire control parameter that wasnot available on the basic AH-1S

was accurate target range data.This is especially true at thelonger effective range of the 20mm cannon. Accurate rangedata also is required to permitthe full use of the standoff rangecapability of the TOW missilesystem. In the modernized AHIS accurate range information isprovided by a neodymium laserrangefinder which is integratedinto the telescopic sight unit ofthe airborne TOW system figure6). This modified system is knownas the laser augmented airborneTOW system. An engineeringdrawing giving details and identification of parts may be seen

FigureLaser ugmented irborne TOW


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Figure 7Characteristics of Laser Rangefinder Subsystem

TRANSMITTERLaser mediumSwitchingWavelengthBeam divergence

Neodymium VAGdyeQ1.06 lAm80 in 0.5 mradRECEIVER

Detector typeMax rangeInstantaneous FOV

on page 42 figure 6 this issue.The laser provides four digitrange values through the TSUeyepiece to the gunner anddigitized serial data ranges toboth the head-up display andfire control computer in less thana quarter of a second after lasertrigger closure. The laser is capableof ranging to 9 900 meters. Multiple targets can be discriminatedand the gunner is provided withmultiple target indication.As shown in figure 6 thesystem hardware consists of atransmitter receiver and display

mounted within the sight and anelectronics box mounted on top

silicon avalanche9900 meters2 mrad 10

of the TSU. Complete integration is accomplished at aweight penalty of 18 pounds anda power dissipation of less than200 watts.Some of the more importantcharacteristics of the laser rangefinder subsystem are listed infigure 7.Another feature which wasincluded was a capability toestablish a minimum range gate.The gunner can adjust this gateand exclude laser returns nearerthan the gate value such astrees in front of a target.

The modernized Cobra firecontrol system is tied together

Figure 8Fire Control Computer

by the digital fire control computer. The FCC is shown infigure 8. The small cylindershown in front of the unit is theboresight memory module whichpermits boresight data to betransferred from the FCC in theCobra to a replacement FCC ifthe computer fails. Thus it is notnecessary to reboresight thesystem when the computer isreplaced.

The modernized Cobra firecontrol computer is a 16 bitparallel general purpose digitalcomputer. t has evolved fromthe Teledyne TDY-43 family ofaerospace minicomputers. Thecomputer is mature equipmentusing TTL-MSI components asthe primary technology base.The FCC interfaces with all ofthe weapon sighting and sensorsubsystems on the helicopter toprovide multimode fire controlsolutions. The crew makes modeand weapon selections throughthe cockpit controls and the FCCprovides coordination betweensights sights and sensors andsights and weapons.

The multifunction operation ofthe FCC includes the following:

Solves ballistic equations foreight types of 2.75 rocket and 20mm rounds providing rocketlaunch line and gun predictionangle based on instantaneousatmospheric range and target-helicopter velocity conditions. Performs control and switching for the various system modesof operation and establishespriorities. Generates drive signals forhead-up display symbology. Performs self test interfacetest and provides fault indications. Performs required computations to support the fire controlsolutions. Stores boresight transformation matrices for electronicboresight corrections betweenweapons sights and sensors.


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A RBORNE LASER TRACKERPILOT S HELMET SIGHT

GUNNER S HELMET SIGHTHEADS-UP DISPL YIR DATA SENSOR

TELESCOPICSIGHT UNIT

LAUNCHEROUTBOARDWING STORES(SAME O RH)

This kind of precision is accom-plished in the factory duringassembly of the AH-IS bymeans of highly accurate assem-bly jigs and a large, rigidboresight fixture with high preci-sion optical telescopes and colli-mators. The factory boresightfixture is shown in figure 10.

Figure 9

I t is easy to see that aboresight fixture as large andheavy as the factory fixture isnot practical for application inthe field. BHT therefore, under-took the design of a boresightfixture capable of providing therequired alignment accuraciesbut more suitable to field use. Aprototype field portable bore-sight fixture is shown mountedon the nose of an AHlS in figure11. This unit provides the samebasic functions as the factoryboresight fixture. The boresightfixture is used with standardAnny elbow borescopes and anew unit called the boresightcontrol ler figure 12).

Components Requiring BoresightingThe FCC provides ballistic solu-tions at a rate of 50 times persecond.The FCC is capable of 420,000operations per second using astandard mix of instructions andhas a memory capacity of 8,192words installed and 8,192 wordsadditional growth capability onthe same memory card. Usingspare card spaces for additionalmemory the growth capability is49 152 words. The presentoperational program occupies7,900 words of memory leavingmore than 100 percent growthcapability without adding cardsand the 50 Hz fire controlsolution rate consumes .60 sec-onds per second of operatingtime leaving time for 66.7 per-cent growth in the operationalprogram.

The modernized Cobra gunand rocket subsystem is capableof delivering highly accuratelong range gun and rocket fire.For this capability to be realized,however, the elements of thearmament and fire control sys-tem must be precisely alignedOCTOBER 1979

with each other. The process ofbringing all of the elements ofthe system into alignment isreferred to as boresighting. Infigure 9 the components requir-ing boresighting are identified.The orientation of each of thesecomponents must be mechani-cally aligned and/or electron-ically compensated with respectto the aircraft reference on topof the TOW telescopic sight unit)to accuracies ranging from 0.25degree down to 0.015 degree.

The boresight controller iselectrically connected to the firecontrol computer and permitsthe aircraft armament repainnanto use the fire control computerto assist in boresighting thesystem. This is one of the majorfeatures of the new fire controlsystem for the AH -I S. The firecontrol computer automaticallycompensates for boresight errors

Figure 1Factory Boresight Fixture


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FigurePrototype Field Boresight Fixture

among the armament and firecontrol components by storingthese errors during boresightingand then incorporating boresightcorrections dynamically into thefire control solution duringactual firing of the weapon.

The boresight concept for themodernized Cobra armament

and fire control system has beendeveloped with careful consideration given to the problems ofmaintaining and replacing components in the field. f it isnecessary to replace the telescopic sight unit the systemmust be reboresighted. Thehead-up display unit the air

Figure 2Boresight Controller

data sensor and the fire controlcomputer can be replaced without reboresighting. The boresightcorrection data that is stored inthe fire control computer iscontained in a small module onthe front panel of the computer.This module is removed byunscrewing a finger tight connector pulling out the boresightmemory module and trans-ferring it to the replacementcomputer.

The modernized Cobra boresight kit provides a number ofadvantages over the approachused on the AH 1Q. Despite themuch tighter accuracy requirements and the new componentsrequiring boresighting the newsystem can be boresighted inconsiderably less time thanbefore. This is due primarily tothe fact that in boresighting theAH-1Q it was necessary to jackup and level the aircraft andout targets over a large clearlevel area and all of the finalalignments were done by meansof adjustment of resolvers ormechanical means. In themodernized Cobra it is notnecessary to jack up or level theaircraft; day or night indoors orout any space large enough tohold the aircraft will do; notargets are required; andfinally most of the highaccuracy adjustments are eliminated because the fire controlcomputer stores these smalldifferences and accounts forthem in the fire control solutions.

The elements of the modernized Cobra fire control subsystem were brought together forthe first time in the SystemsIntegration Laboratory at theBell Helicopter facility in HurstTX. Figure 13 shows the Cobraforward fuselage section thatwas used extensively in theintegration testing. Each of thesystem components was installed in the location where itwould go in the operational

12 U.S. ARMY AVIATION DIGEST


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aircraft and cable runs weremade identical to those used inthe aircraft. As each unit wasdelivered, it was functionallychecked, interfaces were verifiedand then the units were installedand interconnected.Then began the timeconsuming task of validatingand debugging the computeroperational flight program andthe functional interaction of thevarious parts of the fire controlsubsystem. Many interfaceincompatibilities, digital datachannel problems and softwarebugs were discovered and cor-rected in the Systems Integration Laboratory. By the use ofthe integration lab it was possi-ble to have the fire controlsystem debugged and operatingby the time the first prototypeCobra was ready. In August1978, 13 months from the startof the development contract, thefirst modernized Cobra fire con-trol system was delivered toYuma Proving Ground, AZ forthe critical issues demonstrationtest firing program.

In the critical issues testing atYuma the fire control systemperformed exceptionally well.The 20 mm gunfire specificationcalls for azimuth and elevationerrors less than 10 milliradiansRMS required 6 milliradiansRMS desired) over a spectrum offlight, range, wind and targetmotion conditions. Rocket test re-sults while not as spectacular asthe gunfire results show markedimprovement over the results ob-tained without fire control. Armydevelopment testing and opera-tional testing which are under wayat the present time should provideadditional data to further refinethe test results.

Bell Helicopter Textron smodernized AH -1S is the freeworld s first production attackhelicopter with a completelyintegrated full fire control cap-ability. All the new componentsOCTOBER 1979

Figure 3Systems Integration LaboratoryCobra Forward Fuselage Section

contribute to impressive weap-ons accuracies never beforeachieved in a production helicop-ter. The AH -1S will continue tobe the front line antiarmoraircraf t for 20 or more years. Tocapitalize on the effective firecontrol system, a night capa-bility can be added. The firstphase of examining this im-provement was completed inAugust 1979 when a FLIR TOWnight sight was used to guidemissiles to target impact duringa pitch black night. Otherimprovements are under con-sideration. The modern fire con-trol is one important step inkeeping the AH-IS up to date.

Mr George l Cohill

13


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Air To Air act Or ictionthe Soviets can be expected to use this form of offensiveaction when presented with lucrative targets

T HE CONCEPT OF a helicopter versus helicopter threat hasbeen discussed in tactical aviationcircles for the past 10 years. Init-ially there appeared to be a greatdisbelief concerning the subject.This skeptical attitude slowly hasevolved to one of concern and in-terest.

The question most often askedconcerning air-to-air regards capability and probability of engagement. The answer to both questionsalthough complex and qualified with

4

tain arl DaschkeThreat Branch

Directorate of Combat DevelopmentsFort Rucker L

many if's and maybe's: ' is a re-sounding affirmative . The fact isthat the Soviets have fielded tactical systems capable of air-to-airemployment. are most probablyconsidering the air-to-air potentialof the systems, and can be expected to use this form of offensiveaction when presented with lucrative targets. Let's examine each ofthese factors more closely. Equipmen The Soviets arefielding an ever-increasing numberof Hind and Hip series helicopters.

These aircraft are armed (or arecapable of being armed) with alethal and versatile weapons package capable of supporting an air-to-air role. Both the Hind and Hipcan mount weapons ranging frommachine and gatling guns, aerialrockets and the most soph isticatedantitank guided missiles. to multi-and general-purpose bombs.

The Hind A and newer Hind 0represent a major advance n Sovietrotary wing kchnology. The air-craft has been designed to survive

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18/72

~ h a f s n B A )In aviation training literatureSQT Help For The 93H

A N OFTEN ASKED questionis, How can I better preparemyself for the skill qualificationtest (SOT)' "" Well. the re is somegooJ news for those who have themilitary occupationa l specialty(MOS) of 93H / J.

The second edition of the SOTfor MOS 93H / J is in the field. This

2LT David R HalversonCourse Development Division

Directorate of Training DevelopmentsU. S. Army Aviation CenterFort Rucker AL

is a newly revised edition. Testingfor MOS ~ h e y l . n this monthand will begin for MOS 9]J on 1November. You sho uld rece iv e th eSOT notification booklet from yourunit at least 60 days before youhave to test. Study the info rmationin the notification bookle t carefully. It points out the specific areas

Figure 1Air Traffic Control Extension Courses

(TEC)TEC Lesson Number Title

I. 4-222-01 1 6201-A (Part I Co ntrol Information Symbols4-222-o11-6201-A (Part II ) Co ntrol Information SymbolsSubject: Basic ATe co nt rol symb o ls used o n ATe flight pr og ress

2. 4-222-011-6203-A Clearance AbbreviationSubject: ATe clearance abbreviations use d o n ATe flight progress strips

(as th ey re lat e to th e Soldier's Manual) upon which you will be tested.It is your bes t guid e for preparationand success on the SOT.

Another source of informationis TEe, which spells out trainingextension courses. They are multimedia, self-paced. validated les sons pr epa red to help you do your

SM Task No.011-145-1030

o 1 145-1OJO

AvailabilityOct 1979Oct 1979Oct 1979

3. 4-222-011 -6204-A Miscellaneous Abbreviations 011-145-1030 Oct 1979

16

Subject : Abbreviations used to indicat e typ e o f approach requ es ted by th e pilo t on flight progress st rip s4. 5-222-0 11 -62 17-F (Part I Aircraft Identification 01 1-145-10214-222-D11-6217-F (Part II) Aircraft Identification

Subject : Phraseo logy used when transmitting aircraft identification over ATe radio and int er ph o ne systemsS. -U22-0 11 -62 19-F Radio and Interphone Usage 011-145-1021Subject : Frequency usage, authorized transmissions and message pri o rity

Oct 1979Oct 1979Oct 1979

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6. 5-222-0 -6211-F SVFR Arrival and Departure Strips 0 -145- 1030 Dec 1979Subject : How to fill o ut SV FR arrival and de parture s trips using info rm a tio n provided in an AT C tower environm ent7. 4 5 17-011 -6006-A Part II ) Hourly Weather Sequence Reports 0 11 1 45- 10 18 Oct 1979

Su bject : Wea th er and o bstru ctio n to vis io n symbo ls8. 4-517-0 -6007-A Part III ) Hourly Weather Sequence Reports 0 -145- 10 17 Oct 1979Subjec t : In te rpreta ti o n o f sea level pr ess ure, surface wind, a ltimeter se tting and runway visual range RVR )9. 6 0 m ~ A Part IV) Hourly Weather Sequence Reports 0 11 -145- 10 17 Oct 1979Subject : Int e rpreta ti on o f OT AMs. PIR EPs a nd Re marks

10 . 4-5 17-6009-A Part V) Hourly Weather Sequence Reports 0 11 1 45- 101 7 Oct 1979Subjec t : Inte rpret a co mpl ete hourl y weather sequ ence reportII 4-517011 601 2-A Hourly Weather Sequence Reports 011-145 101 7 Oct 1979Subjec t : Int e rp retati o n of Na tio nal W ea ther Se rvice, Navy and Air Wea th er Se rvice termin al fo recas t12. 5-222-011-6209-F Introduction to Flight Progress Strips 011-1 45- 1030 Dec 1979Subjec t : Use of fli ght prog ress strips, how to mak e co rr ecti ons o n the s trips. use o f standa rd and no nstandard block s. bloc ks usedfor type of a ircra ft and spec ial equipment des ignator and bloc k used fo r a ircraft id entifica tion13. 5-222-0 -6210 F VFR Arrival and Departure Strips 0 11 -145- 1030 Dec 1979Subjec t : Initi atio n of V FR arrival and departure strips14. 5-222-0 -6213-F Clearance Transmissions for Flight 0 11 -145-1027 Dec 1979

Progress StripsSu bje ct : Rece ive and re lay IFR clea rances using s tanda rd air tr a ffi c co nt ro l termino logy15. 5-222-0 11 62 14-F Flight Progress Procedures 0 -145- 1030 Dec 1979

011 -145-I OJ7Subjec t : Initia te. ma int a in and reco rd IFR and SVFR clearance inform atio n on flight prog ress strips16. 5-222-011-6215-F Number Usage 0 11 -145-1021 Dec 1979

Subjec t : Ph raseology used to tr ansmit serial numb ers, a ltitud es, flig ht leve ls, MDA a ltitudes, DH altitudes, fie ld elev ati on.altimete r se ttin g. surface wind , hea din gs, run way designatio ns, radio frequ encies, spee d and miles17. 5-222-011 -6216 F Facility Identification 011-1 45-1022 Dec 19790 -145- 1040Subject : Phraseo logy used when tr ansm itting fac ility id entifica ti on and o peratin g pos itio ns18. 5-222-0 -6220-F Provide Emergency Assistance 0 -145- 1042 Dec 1979Su bject : Determine if a give n situ a ti on is an emerge ncy. proced ur es for ov erdu e air cra ft . proced ures for handling ELT signals.decode emerge ncy inform a tio n and initia te fac ility c ras h net19. 5-222-011-6 212-F IFR Arrival and Departure Strips 0 11 -145- IOJO Dec 1979Su bjec t: How to fill o ut IFR arriv al and departure s trips, usin g info rm a ti on prov id ed in an ATe tower enviro nment

Figure 2I AdvNCo lPTC BTC Basic NCO SkillSkill Level 2 Skill Level 3 Course Course Level 5

93 H20 93J20 92H10 93J10 93H J40 93H30 93J30 93J50R14 R34 R 7 R37 S12 R 2 R32

Subcourses 7 9 9 9 48 35 35 5

lessons 24 8 18 15 83 75 83 6

Credit 44 45 44 43 230 188 194Hours

*Courses which parallel tasks from the Soldiers Manual

OCTOBER 1979 17


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job better. TEC can come in theform of audio on ly (uses a standardcassette tape and player), aud iovisua l (uses a super eight film loopand cassette tape), and printed text(usua lly written as programed text).They are short and easy to use,and provide you with the information yo u need to do we ll on yourjob and the SOT. There are a number o f these lessons already ava il-ab le to a id yo u with the comm onSoldier's tasks. A total of 19 newlessons , specifica lly fo r air trafficco nt ro l, will be avai lable by theend o f this year (some of these canbe seen in figure 1 on the preced-ing pages. TEC lessons are avai lab le to you at your post's TEC library.

Program (ACCP). To date , thereare eight correspondence coursesfor MOS 93H / J personnel. Five ofthese courses track the tasks fromthe Soldier's Manual to help youdo better on the SOT (see figure2 located on page 17 .

Not only will you be able to do abetter job on the SOT, but by com-pleting these courses you also wi llbe better ab le to accomplish yourjob.

What, there is more? Yes, youcan earn promotion poin ts to gradeE-6 at a rate of one point for each5 credit hours satisfactorily com-pleted. These courses with thenumber of subcourses, lessons andcredit hours are listed in figure 2.

you. It is easy for you to enroll; allyou need to do is see your unittrainer or the post education officerand submit an app li cation (DAForm 145). Department of the ArmyPamph let 351-20-3, U.S. ArmyAviation Center CorrespondenceCourse Catalog, lists all coursesand subcourses (with subcoursedescriptions) to help you with yourselection .

The Commander's Manual liststhe TEC lessons and ACCP coursesthat will help you to prepare forthe SQT. Ask your commander ortraining NCO for assistance in locat ing the training materials youneed. Prepare o w ~ Remember,preparation is the key to the SQT -the SOT is the key to promotion-and promotion is the key to yourcareer.

Another way in which you mightprepare for the SOT is by enrollingin the Army Correspondence Course No matter what skill level youhold, there is a course designed for

18

OH-58 Kiowa A CAircraft Qualification CourseFrom the Army Training Support CenterNewport News, VA

Aviators preparing to qualify in the OH-58 Kiowa will be interested in theacademic instruction in a correspondence course being compiled at theU.S. Army Aviation Center, Ft. Rucker, AL.The correspondence course, which will be available in the second quarterof fiscal year 1980, provides the minimum academic training necessary foraviator qualification in this particular observation helicopter.Individual subcourses are those specified in TC 1-137, Aircrew TrainingManual Observation Helicopter, October 1978, and includes the followingsubjects: Introduction to the OH-58A, C AQC, Structure, Fluid Systems,Flight Controls and Rotor Systems, Mission Employment, Power Plant andRelated Systems, Electrical Systems, Weight and Balance and Operationallimitations, Performance Planning, Avionic Equipment, Inspections, TestFlight Requirements, Precautionary Measures and Critical Conditions, andan Operator's Manual Examination.Completion of 10 hours flight training in their units, as specified in TC 1-137, combined with the academic instruction, will provide aviators with 44hours of instruction.Individuals can enroll by submitting a completed DA Form 145, Army Cor-respondence Course Enrollment Application, to:Army Institute for Professional Development (IPOU.S. Army Training Support CenterNewport News, VA 23628

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Vi WSFRomRE DERS

Editor:In your article (EPMS Corner datedJune 1979) I noted that the 67VNYUXwears two hats, production and quality.My view of the subject is that whenyou take a supervisor that has a maintenance officer pushing production thata supervisor becomes productionminded. In my 10 years of experienceI have never seen a maintenance officer yell, "Quality" day after day. Qualityis mentioned only after a mistake, andis pushed for a day or so. Then usuallyin the same breath we want quality butdon t let production suffer.I have worn both hats and preferthe one of quality. When quality suffers accidents happen.

Editor:

SSG Larry A. CottonHHT 3rd ACRFt. Bliss, TX 79916

As a long-time reader of the Digest Ihave particularly enjoyed LaurenceEpstein's articles on the evolution ofaviation logistics. However, please forgive me if I do a little nit-picking.

Epstein, in recounting the arrival ofthe new aircraft during the KoreanWar states, Another excellent aircraft. the de Havilland L-20 Beaver(U-6) arrived in December 1952. Actually,the L-20 came to Korea several monthsearlier than that. Captains Tom Hall.Guy Meiss and Carl Colozzi had beentrained in Canada to fly the Beaver(Tom was the L-20 test project officer)and had flight-delivered the first production aircraft. Guy brought thefirst Beaver to Korea in the spring of1952. Almost immediately he begantraining pilots of the Dragon Flight,"the Eighth Army Flight Detachment.

OCTOBER 1979

stationed at the old race track airstripin Seoul. In the meantime, Carl wasassigned to the 3rd Infantry DivisionLight Aviation Section (the first trulyconsolidated division level Army aviation company ). Because of this presence, the first L-20 assigned to a combat unit came to the 3rd Division.Frenchy Fournier and I were amongthe first pilots trained by Carl Colozziand we were in hog heaven flyingthat big powerful bird.Interestingly, division , corps and theEighth Army commanders did not sharethe aviators' enthusiasm ahout flying inthe Beavers. Somehow there was moreprestige to he found in the privacy ofan L-19 0-1 Bird Dog). Then. too, theL-19 could get in and out of shorter,narrower places than could the "Iumhering" L-20. At any rate, very seniorpeople assigned to or visiting Koreacontinued to be flown in L-19 and H-13(OH-13 Sioux) "Iimousines"; the Beave rwas our hus.

As I recall, by December 1952 therewere several Beavers in Korea - andone L-23 (U-8 Seminole), flown hy thelate and great CPT Jim Lefler - threeor four of which were assigned to theDragon Flight. Nevertheless, whenPresident-elect Eisenhower paid hispre-Christmas visit to Korea in thatyear, he and every one of the verysenior officers accompanying him madeall their trips in L-19s. It read likewho's who: - Omar Bradley, Radford,Mark Clark, Ridgway, etC.-what aline of Bird Dogs climhing out of thesmoky Seoul morning smog The considerable press corps flew ignomiouslyin every Beaver that could be gathered.For the record, LTC 1. Elmore Swensonflew General Eisenhower in those days.Hugh Gaddis and I leap-frogged fromone destination to another in H-13s.Our mission was to dash in. pick Ike

up and hide him somewhere in thehills in case of a Chinese/ North Koreanair attack.A few days later, Billy Graham andCardinal Spellman came to conductfront-line Christmas services. Theyhadn't heard about the prestige ofthe L-19 and were delighted at the dignity afforded by wooden steps thatwere quickly fabricated and broughtto the passenger door of the Beaver.All we needed were stewardi-darn it

Editor:

COL Colin D. Ciley Jr.U. S. Army, Retired805 Northside Dr.Enterprise, AL 36330

An open question to those responsible for UH-60 mission planningwhat has happened to the door gunner?We learned in Vietnam that the crewfor a UH-l D/ H was four. I keep reading about the UH-60 and its crew ofthree plus 11 combat troops (see page23 of the May Aviat ion Digest). f youwant to tell me that one of the 11combat troops is going to be the gunner, then I ask, what happens in theLZ? Does the gunner wire his M60trigger in the pulled position and jumpout with the squad? Seriously, to be adoor gunner requires some special training. He is a key member of the crewresponsible for maintenance of theguns and he helps the crewchief maintain the ship. When can we push politics aside and admit that the UH-60requires a crew of four?CPT Victor A LentArmy Aviation Support FacilityDistrict of Columhia National GuardDavison U. S. Army AirfieldFt. Belvoir, V A 22060

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Load Em Up. Co. A, 327th Infantry troops load onto UH-1 Huey helicopters tomove out on a live fire air assault at the north impact area

ir ttackBringing The Birds. PFC Louis Earles, Co. A , 327th Infantry , flags in the UH-1Huey helicopters to the pickup site as the rest of his company waits in the grass

off to the left and right

20

Dean Fletcher1 1 st Airborne Division Air Assault)Public Affairs Office

Fort Campbell, KY

T HI CK CLOUDS of artillerysmoke hang deathly over abombed-out field. Suddenly 5roaring helicopters streak acrossthe horizon with their door gunnersfiring up the tree line.

They land.In the bat of an eye, a platoon ofcamouflaged infantry pours out ofthe choppers and races with blaz-ing weapons toward the woods tomeet the enemy.

This war scene is precisely thedrama created by the ist AirborneDivision s concept of air assault.The scene recently became reality



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at Ft. Campbell, K Y, at the northimpact area became realitywith real bullets.

Soldiers of Companies A and B2nd Battalion, 327th Infantry tookpart in the first tactical live fire airassault at Ft. Campbell since theScreaming Eagles return fromVietnam, according to LieutenantColonel Clifton Franks, 2nd Battalion commander.

Combat air assault is nothing unusual for the 10 1st. Air assault isthe heart, the meat and potatoes,of the division's purpose. But theair assault had an added touchwhen live ammunition was used.

I t was a good exercise, saidCaptain James Gibson, CompanyA commander. Anytime you canget the Soldiers out there firingreal bullets instead of blanks, itadds to the learning and enjoymentof the exercise.

' It also puts more stress on thenoncommissioned officers and platoon leaders as the threat of something serious happening increaseswith the use of live ammunition,Captain Gibson continued.

The air assaults were planned tostopwatch precision. The sameprecision that would be needed inactual combat. First, the 2nd Squadron , 17th Cavalry performed visualreconnaissance of the landing zone.Battery A, 2nd Battalion, 31 st FieldArtillery unleashed 105 mm and155 mm howitzer fire on the landing zone.

The artillery fire lasted 6 minutes.As the smoke was clearing, threeAH-I Cobra gunships from Company A, 229th Attack HelicopterBattalion , flew over the landingzone firing 20 mm ammunition atthe targets.

On the Cobras heels came ISUH-\ Hueys from Company C,158th Aviation Battalion with acompany of infantry. The 327thtroops riddled the woods with M-16 M-60 machinegun, mortar andantitank fire. The infantry company stayed on the ground for al-

OCTOBER 1979

Getting Ready. SP4 Julian Garvin , Co. A, 327th Infantry, second platoon , loadshis M 16 magazines with live ammunition

most an hour before the Heuysreturned to pick them up.

It was all a pretty good firstcut, said Brigadier General WilliamC. Louisell Jr., assistant divisioncommander (operations), who was

o n hand to observe the exercise.The live fire air assault exercise

was carried out twice by the 327thSoldiers. Alpha Company launched the first assault with Bravo Company's assault coming 3 days later.

n Battle Heat Smoke fills the air as 2LT Robert Olds (right), Co. A, 327thInfantry, signals his troops to move forward . In the foreground SGT JohnBigham uses PFC Gerald Riggs radio

21


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u s RMY

VI TIONST ND RDIZ T ION

Directorate of Evaluation Standardization

R[P RT T TH[ fl[LODE S welcomes your inquiries and requests to focus attentionon an area of major importance. Write to us at: CommanderU S Army Aviation Center ATTN: ATZQ-ES Ft Rucker AL36362; or call us at AUTOVON 558-3504 or commercial 205-255-3504. After duty hours call AUTOVON 558 6487 or com-mercial 205-255-6487 and leave a message

What s In Chart?W HAT'S IN A chart? I f thisquestion refers to a helicop

ter performance chart in the newformat, the answer is, a lot. Thenew performance charts provide awealth of information that has neverbefore been available to aviatorsfor use in optimizing Army aircraftoperations. They give aviators virtually unlimited flexibility for determining aircraft performancecapabilities and limitations.A good example of the varietyof information appearing in thecharts is cruise performance. Inthe past the only airspeeds for whichpower required and fuel flow information was given were maximumrange and maximum endurance.Now, aviators can find informationfor all cruise speeds up to Vne.Other information that can be derived from the cruise charts s fuelflow for any given power setting;conversion of indicated airspeedto true airspeed and vice versa;changes in fuel flow with enginebleed air/ anti-ice on and off; Vne;22

maximum endurance/ rate of climb/range airspeeds; excess torque forrate of climb; torque limits andtorque available; and allowablegross weights for specific conditions.

Some of the most significant features are:

Charts are arranged in a sequence that requires a minimumamoun t of cross-referencing formost situations.

Old type charts that have noplace n performance planning havebeen removed from the new manuals, e.g., horsepower/ torque conversion table, density altitude chartand standard atmosphere chart. Color has been added to better portray the areas in which performance s restricted. All charts are based on pressurealtitude and temperature to eliminate the need to convert to densityaltitude. This also shows vividlythat density altitude s not a goodperformance indicator.A brief look at the charts shows

the variety of information available for performance planning byArmy aviators.

Torque Available Presentspower available n the terms reflected on the instrument panelwhich , in most cases, s torque not horsepower. The limitationsimposed on the use of torq ue areshown. For example, the UH-IHHuey chart shows a calibrated torquelimit of 50 pounds per square inchpsi), beyond which no informations presented. The chart that showsthe 30-minute operating limit reflects values based on the exhaustgas temperature (EGT) limit yellowrange 610 degrees to 625 degreesCelsius). This tells aviators that theycan anticipate the EGT being inthe yellow range when maximumtorque available less than 50 psi)s used. Additionally, if the maximum torque available (30-minuteoperation) s less than 50 psi calibrated torque, revolutions perminute bleed-off may be experienced if collective pitch s increased



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above that value. These charts alsodepict the differences in calibratedtorque and indicate torque for individual engines when the difference is significant.

Hover Using the maximumtorque available derived from aprevious chart, aviators can determine maximum hover height foran estimated gross weight or maximum gross weight for a desiredhover height. Hover performanceestimates reflecting changes inpressure altitude, temperature andgross weight can be made for allphases of a mission. The hoverpower check, based on the predicted values from this chart, tellsthe crew if the aircraft is performing as estimated and if flight shouldbe attempted.

Takeoff These charts showthe distance to clear obstacles andare based on the hover capability

determined previously. The optimum airspeed is shown in the toppart of the chart while various climbairspeeds are shown in the lowersection. Comparisons of the effectsof differences in airspeeds and hovercapabilities can be made. Also noteworthy is the significant differencesin performance for the two techniques-level acceleration and climbacceleration.

Drag This chart, when usedin conjunction with cruise charts.shows the effects on power required,fuel flow and airspeed with variousexternal stores.

Climb Descent The top portion of the chart shows the rate ofclimb/ descent for changes in torque.This information also must be usedwith cruise data. The most significant information shown on the bottom portion of the chart is the effects of airspeed on autorotation

performance. The chart shows thearea where powe red flight may notbe possible for specific airspeedsand approach angles. I n practicalterms, it tells the pilot that as anglesincrease, airspeeds used for the approaches become appreciably morecritica l Idle Fuel Flow This chartshows the fuel flow for two conditions and allows the crew to determine if the helicopter sho uld beshut down or idled while waitingfor loading/ unloading, flight clearances, etc.

Examples have been providedto aid the user in determining aircraft performance. Since the number of examples in the Operator'sManual must be limited becauseof the tremendous vo lume of information that can be derived fromthe charts. it is essential that unitscond uct formal training on theiruse.

I

E GLES VE

Ft. Campbell Soldie rs load one of fourHuey helicopters onto n ir ForceC 5A Galaxy transport aircraft duringdeployment operations for the Domin-ican Republic early Labor Day morning

A BOUT 60 Screaming Eag leSoldiers arrived in Santo Domingo on J September to providehelp to the disaster stricken peopleof the Dominican Republic.

Following close on the heels ofthe Hurricane David's ravagingforces. the 10 1 t Airborne DivisionSoldiers left Campbell Army Airfield. Ft. Campbell. KY. early LaborDay morn ing destination De

Las Americas International Airporton the Caribbean island.

Working through Labor Day'searly morning hours. crews loadedfour UH-I Huey helicopters. fourtrucks and other necessary equipment onto an Air Force C-141 Starlifter and a C-SA Galaxy.

The flight route to the Dominican Republic avoided HurricaneDavid and lasted about 4 hours.

Troops from the IOlst AviationBattalion. 426th Supply and Services Battalion. Division Pathfindersand Division Support Commandwent as a self-sustain ing task force.As such. they took a petroleumlaboratory team for testing aircraftfuel and a water purification teamto ensure the So ldiers have available drinking water while in theRepublic.

Plans ca ll for Task Force EagleSave to remain in the Republic forabout 2 weeks conducting disasterreconnaissance and providing aidwhere\er and whenever possible.IPAO. 10 1 t Airborne Division (AirAssault)1

2]


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Fort Rucker Doctors board

CH 47eployment

etty GoodsonPublic Affairs Office

Fort Rucker L

T HE CONCEPT HAS bee n proven by OperationNorthern Leap H-47C Chinook helicopterscan get from the United States to Europe under theirown rotors.Four of the tandem rotor helicopters did it in August,

and two of the people involved in the 6,000-mile tripwere from the U.S. Army Aeromedical Research Laboratory at Ft. Rucker.Major Dr.) Lawrence R. Whitehurst served as anevaluator and a flight surgeon and Major Dr.) AaronSchopper as a psychologist.

Sponsored by the Army Training and DoctrineCommand, Ft. Monroe , VA, the operation s purposewas to evaluate the Chinook s self-deployment ability.It is believed that such deployment will be essential ifthe Army s aviation resources are to be used successfully in any future European conflict.

The helicopters, accompanied by an Air Forcefixed wing support aircraft, left Ft. Carson, CO on 6August and arrived in Heidelberg, Germany on 20August. En route stops were made in Iowa, Pennsylvania, Maine, Canada. Greenland. Iceland, Scotlandand England.

Each Chinook carried three pilots. two crewchiefsand an evaluator.

Eight of the pilots, including the exercise commander, were from the 179th Aviation Company at Ft.Carson. as were all the crewchiefs. The other aviatorswere Army National Guard troops from Stockton.CA. and Army Reservists from Everett. W A.In addition to Major Whitehurst, evaluators were

4

Major Whitehurst in front of CH-47C Chinook

two majors from the U.S. Army Transportation School,Ft. Eustis, VA, and a Canadian Forces officer.As the crews physician , Major Whitehurst said

there were few medical problems. Pe rsonal stress andfatigue were two areas the evaluators checked closely,and Dr. Whitehurst said the test aircraft had theminimum crew that could accomplish such a missionwithout being subjected to undue strain.He said the average flight period lasted 2 hours.except for the leg from Iceland to England whichtook almost 9 hours, including a refueling stop inScotland.

That portion of the trip. according to the doctor,also covered about 700 miles of water and is thelongest overwater crossing an Army helicopter hasmade.

Further data on the crews attitudes and stress willbe obtained when the results of Dr. Schopper s psychological tests are analyzed.

The psychologist, who made the trip in the supportairplane, performed tests before the start of the missionand th en conducted brief interviews and testingprocedures at stopover points.Having the Chinooks go for extended periods oftime at high gross weights resulted in a plague ofmaintenance problems caused by vibrations, MajorWhitehurst said. And a few times the trip had to bedelayed while parts were flown to them.

Major Whitehurst was awarded the Air Medal forOpe ration Northern Leap, and Major Schopper received the Army Commendation Medal. . . .



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L l J E ~ T I 1 H ~ E U [ ] L L J T ~ [ ] ~ P L I 1 ~290 100 98 99

MO ERNIZEAH-IS

I PRODUCTIONAH-lS

UP GUNAH-lS

MO ERNIZEAH-lS

Modified from ex istingAH 1Gs Low glint canopyNew instruments

New blade at 49Radar warningCONUS Nav radiosRAM improvements

2 mm cannonStores management1 KV A alternator

Laser rangefinderLaser detectorNew fire controlIR jammer

Figure 1

f iELDING THE AH-1S CobraTOW antiarmor attackhelicopter to operational unitshas been a tremendous success.The combination of proventechnology coordinated management and professional introduction speaks for itself. This newhelicopter has been demonstratedto several European countries anda t the Paris Air Show. In eachcase its capabilities have generated enthusiastic aviator re sponse and positive command interest.The fi rst ship of the 297 newproduction aircraft was deliveredto the Army in March 1977 with

inal delivery scheduled for February 1981. As these new helicopters are delivered from the production line they will be issuedinitially to FORSCOM CONUS units. This fielding began in August1977 at Fort Bragg NC with theassignment of aircraft to the 82dAirborne Division.This article the first of athree-part series addresses thescope of the Cobra program andhighlights the improvements thathave been or will be accomplishedwithin the next few years to modernize fully the AH-1S CobraTOW antiarmor attack helicopter . The second and third parts of

lJL[]SSfUiYADF automatic direction finder lS instrument landing systemAM amplitude modulation KHz kilohertz

CONUS Continental United States MHz megahertzECU environmental control unit NOE nap-of-the-earthNVG night vision gogglesFM frequency modulated

FORSCOM Forces Command RAM reliability availability andmaintainability

New IR suppressorDoppler NavNew transponder andsecure voice

this series will cover the new turretand weapons programs and thefire cofttrol aircraft survivabilityand laser rangefinder/trackerprograms respectively.

MODERNIZATION ACCOMPLISHED IN PHASES: Improvements to the AH-1S new production aircraft will be accomplishedthrough phased product improvement programs. The configuration changes and phasing forthe Cobra fleet evolution to modernized AH-1 S is summarized infigure 1. The first 1 aircraft pro -duced will feature a new canopyand cockpit a new T703 engineuprated transmission plus im-

TOW tube -launched optical/y -tracked wire -guided

TSU telescopic sight unitUHF ultra high frequencyVHF very high frequencyVOR VHF omnidirectional rangeHSI horizontal situation indicator SlAE standard lightweight avionics VSI vertical situation indicatorIFR instrument flight rules equipment

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OT BER 979

Figure 2 AH l S new production Cobrawith IR p intColonel Jay W. Pershing

Project Manager Cobra TS RCOMSt. Louis MOFigure 3 pilot station instrumentpanel and consoles

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proved survivability design features and reliability, availabilityand maintainability (RAM)characteristics.

Figure 2 is the new productionAH-1 S Enhanced Cobra ArmamentSystem ECAS) configured Cobra.The new improved main rotor bladedeveloped by Kaman AerospaceCorporation was installed in April1979 on the 149th production helicopter. The Air Cavalry Troop at Ft.Bliss, X received the first AH-1 Sswith this new improved main rotorblade. A new wing stores 2.75 mmrocket management subsystemand a universal turret capable ofaccepting 20 or 30 mm weaponswas cut into the production line inSeptember 1978 with the deliveryof the 101 st aircraft. A new firecontrol subsystem consisting oflaser rangefinder, ballistic computer,low airspeed sensor and a headsup display will be installed on the199th aircraft which is scheduledto be delivered in November 1979.

CANOPY AND INSTRUMENTPANELS: The production AH-1Smodel has a new outward appearance with its nearly flat canopy.This canopy has seven planes ofviewing surfaces designed to decrease the glint signature and reduce the probability of visual detection during NOE flight.Another advantage of the newcanopy is additional headroom forthe pilot's visibility in NOE flight.

The cockpits of both the pilotand copilot/gunner have been redesigned with a new instrumentpanel to provide .,for crew efficiency during NOE and IFR flight.Figure 3 is the pilot's new instrument panel. The major improvement in this panel is the groupingand the size of the instruments.The torque meter, pilot steeringindicator and radar altimeter arethe primary tactical instrumentsused by the pilot to accomplish theantiarmor mission. These threeinstruments are located in thecenter of the panel, under theglare shield, and are 3-inch diameter in size. They facilitiate NOEflight and maneuvering of the28

helicopter into position for firingthe TOW missile and keeping itwithin maneuver limits until missile impact.

Flight instruments are arrangedin a standard IFR T configuration comprised of 4-inch diameterVSland HSI grouped with 3-inchairspeed, altitude and verticalspeed indicators. The number ofengine instruments is reduced byusing dual scale 2-inch instruments where possible. All instruments are equipped with wedgeglass to distribute red lightingevenly over the instrument. Thedial range markings, numeralsand letters are designed to bereadable under extremely lowlight red illumination and whenusing night vision goggles.The instrument lightingswitches are located on the leftside of the panel and provideselective illumination of relatedinstruments for engine, flight,tactical and console groups. Thelight intensity is rheostat controllable and a toggle switch isprovided to the pilot and copilotfor returning lighting to the panelif the NVG lights malfunction.

NEW INSTRUMENT CAPABILITY: In addition to the grouping ofthe instruments on the panel,there are several new instrumentsthat have been added to improvethe effectiveness of the AH-l Shelicopter. The radar altimeter oneof the three primary tactical instruments, provides the crew theability to fly safely at NOE duringperiods of poor visibility. TheAPR-39 radar warning receiver -a survivability improvement - issimple and lightweight, capable ofbeing used during low level andNOE operations. This device provides the pilot sufficient warningin time to take evasive action before receiving fire from radar directed enemy antiaircraft weapons. This warning is providedthrough an audio and a visual display in the form of a strobe line ona cathode ray tube.

HSI and VSI These two instru-

ments provide a system thatmakes precision IFR flight andILS, VOR and ADF approaches asnatural in helicopters as it has become in fixed wing aircraft .Growth capability has been incorporated for future navigationsystems such as doppler andflight director computers.

Copilot Panel Figure 4 on thefacing page shows the arrange-ment of the instruments used bythe copilot/gunner. These flightinstruments also are grouped in astandard IFR T configurationlocated on the right side of thepanel and are all 3-inch diameterin size. A standby magnetic compass is mounted above and on theright side on the copilot/gunnerpanel glare shield. All of these instruments are marked and lightedas the pilot's. The eyepiece for theTSU is in the center of the cockpitand is used by the copilot to locatethe target and guide the missile onto the target during the firingsequence.

An ECU has been redesigned forthe AH-l S. The distributionducts and plumbing for ventilating and environmentally conditioning air within the crew compartments have been modifiedand rerouted to adapt to thenew cockpit configuration.

IMPROVED MAIN ROTORBLADE: A new composite mainrotor blade has been developed byKaman Aerospace Corporationfor use on the AH-l S. It has beendesigned to be used on the existing airframe without modifications to the AH-1S or its rotor system. It was installed in April 1979on the 149th new production ECAShelicopter which was fielded at Ft.Bliss in June 1979. This new bladeprovides improved flight perform-ance, survivability features andRAM, while reducing the radarcross section and acoustic detectabil i ty signatures. Figure 5shows the new blade installationon the AH-1 S new production ECAShelicopter. The chord of the bladeis 30 inches wide with the outboard.

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Figure 4 copilot/gunner station instrument panel and console

Figure 5 improved main rotor blade installed on AH 1 S Cobra helicopter

15 percent tapered in both chordand thickness.Figure 6 shows the tapering effect of the new blade and compares it to the present metalblade. The new blade has been de-signed for almost total repairabil-ity of the skin and core aft structure by personnel in field units.This is accomplished with the aidof a heat-pressure pack tool,shown in figure 7, which can accomplish the repair of the bladewithout removing it from the air-

OCTOB ER 1979

craft. A survivability feature ofthe new blade will allow 30 min-utes of flight after being hit witha single 23 mm high explosive, in-cendiary, tracer round and is in-vulnerable to a single hit 12.7 mmround. The through damage,which would result from this typeof a ballistic hit involving bothskins and the core, can be repairedby personnel in the field in lessthan three hours. The maximumallowable operating time for thenew blade is 10,000 hours which is

an increase of 9,000 hours overthe present metal blade.CANOPY ESCAPE SYSTEM: Anew crew compartment escapesystem provides a means of es-cape for the pilot and copilotgunner in emergency situationswhere normal egress is not possi-ble. Operation is accomplished bya ballistic jettison system whichexplosively cuts the acrylic sidewindows from the canopy supportstructure while l inear shapedcharges and thrusters explosively

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Figure 7 Right)-heat-pressurepack special tool installed on improved main rotor blade sectionincorporating repair

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Figure 6 left) - inboard and outboard cross sections of improvedmain rotor blade top) and outboardcross section of standard metalblade

Figure 8 left) - arming firinghandle for pilots canopy removalegress system

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separate the pilot and copilot/gunner entrance doors. Itis totally independent of the aircraft electrical system or of anyexternal energy source, and canbe actuated only from inside thepilot or copilot/gunner station byeither of two arming/firing handlemechanisms. Figure 8 shows thecanopy removal system components for the pilot station.

Other significant improvementsare shown in figure 9 and include:Hydraulic Pump. An electricallydriven pump which takes the placeof the collective control accumulator which provides an unlimited number of collectivestrokes in the event of a mai n hydraulic system failure. It can beused for boresighting of the turretand TOW missile subsystemswithout the need of additionalground support equipment Hydraulic Mule).Rod End Bearing. An improvement to replace current rod endbearings of the hydraulic servocylinder connecting tubes whichwill increase the fatigue life of thebearings to 3,300 hours.Tungsten Carbide Bearing Sleeves. Animprovement to replace mainrotor teflon feathering bearingsleeves with a more durable mate-

NOE COCKPITFOUR LIGHTING CONTROLSELECTRIC LOCKSARMAMENT TOGGLE SWITCHES

RADAR WARNING ANTENNAFIRE DETECTI ON

riel for increasing sleeve life.Standard Lightweight Avionics Equipment SLAE): ARC- JJ4 Radio - An FM communication radio replacing theARC-54/131. t is a smaller,lighter radio that is compatiblewith secure voice systems. ARC-l64 Radio - A UHF-AMvoice communication radio replacing ARC-51. It performs allARC-51 functions but is smaller,lighter and compatible with secure voice systems. It provides 25KHz spacing in the 224-400 MHzband. ARC-llS Radio - A VHF-AMvoice communication radio replacing the ARC-134. It also iscompatible with secure voice systems.CONUS /NAV (ARN-l23). Improvesthe AH-l S navigation capabilityby adding VOR and ILS receivers,glide slope, marker beacon andindicator lights. The CONUS N Vpackage is currently included in theproduction AH-1 S; however futureaircraft will not have this package.Engine Declc Panels. A three pieceengine deck designed to reducebonding separations and providefor replacement of the forwardand middle panels by field units. Italso includes arms which support

Figure 9

No.1 hangar bearing.Antitorque Controls. Providespush-pull tubes between tail rotorpedals and tail rotor pitchmechanism thus eliminatingtroublesome pulleys, sprockets,cables and chains. This improvement is included on the Mod liSmodelsFire Detection. The system installed in the engine compOlrtment includes a single loop sensing element connected to a control unitwhich activates fire warning indicators, located on the pilot s instrument panel.Flex Beam Tail Rotor. A simple uniball feathering bearing with asingle piece hub which reducesmaintenance and provides betterantitorque controllability. Thisimprovement is included on allAH-1 models.

The Cobra attack helicopterhas proven itself to be a viableaircraft for today s antiarmor requirement. It also will complement the advanced attack helicopter in the high-low mix of attack helicopters in the U.S. Armyfighting force of the future.

The next article on the modernization of the AH-l S will coverthe new turret and weapons pro-grams.

FLEX BEAM TAil ROTORFLAT PLATE CANOPY /PROXIMITY WARNING ANTENNA (1-66 ONLY

TUNGSTEN CARBIDE BEARING SLEEVES/ IMPROVED ROD END BEARING

IMPROVED ENGINE DECK

HYDRAULIC PUMPINTERIM I R SUPPRESSOR

CON U S NAVIGATION PACKAGERADAR ALTIMETER ANTENNA

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WING STORES MANAGEMENT SYSTEM

/IMPROVEDM IN ROTORBL DE149 and Sub)

10 KVA ALTERNATOR.

2 m ~ N N O N N I V E R S L TURRETFigure l - Production upgunned AH-l S features

P RTColonel Jay W. Pershing Project Manager, Cobra, TSARCOMSt. Louis, MO

LAST MONTH port one of thisarticle presented an overview ofthe AH - 1 Modernization Program. It focused on the featuresof product improvements andhow the resultant improvementswill be incorporated into theCobra TOW (tube-launched,optically-tracked , wire-guidedmissile) antiarmor attack helicopter fleet.

This article addresses, in part,the new weapon subsystemswhich will increase significantlythe combat capability of CobraTOW attack helicopters.

The requirement to modernizeand upgun the Cobra was defined by a Special Study Group(SSG) during the Priority Aircraft Subsystem Review t Ft .Rucker, AL from November1974 to December 1975. (SeePass in Review, April 75 DI-GEST and liThe Upgun Di-

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lemma/' May 75 DIGEST.The SSG, under the direction

of the commanders of the U. S.Army Armor and U. S. Army Aviation Centers, was comprised ofrepresentatives of TRADOC(Training and Doctrine Command), DACROM (Army Ma teriel Development and ReadinessCommand), subordinate commands, the Cobra Project Manager's Office and field commands.Following affordability analysesof the SSG recommendations bythe Department of the Army staH,Required Operational CapabilityROC) documents were approvedand used as the basis for structuring the current Cobra Moderniza

tion Program.The first major effort to

upgun the Cobra attack helicopter was included in the EnhancedCobra Armament ProgramECAP). Bell Helicopter Textron(BHT) is the prime contractor

and system integrator. Theprogram is divided into twophases to best meet the fundingand development time frames .Phase I includes developmentand qualification of a universalturret to accommodate eitherthe 20 mm or 30 mm weaponsystem and a Stores Management/ Remote Set Fuzing Subsystem. It also will include aircraftinterface aspects and the application of additional fiscal year(FY) 78 product improvementprograms PIPs).

Phase II includes the qualifica tion of a new fire control subsystem, the incorporation of additional PIPs and improvementsin aircraft survivability equipment. Phase II will be discussednext month in part 3 of this article. Figure 1 summarizes thebasic features of the ECAPPhase I Program.

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~ U N I V E R S A ~ ~GUN CONTROL BOX

NIVERSAL TURRETCONTROL BOX

AMMUNITION ;) - - ,

Figure 2- Univers al turret systemSTORAGE U N I T

~ ~U r . i ~ U E R S I 1 L TURR TThe Armament Systems Depart

ment of General Electric in Burling-ton VT developed and manufacturesthe universal turrett. The objectivesof the Universal Turret Program areto provide an improved standoffcapability improve antipersonnel andantimateriel effectiveness andaccommodate either a 20 mm or30 mm weapon. This new turreteventually will replace the M28(7.62 mm/40 mm) subsystemnow installed in the Cobra.

The 101 st new production AH-1 S was delivered in September 1978and was the first to be equippedwith the universal turret and the 20mm M197 gun. The 30 mm weaponsubsystem is still a user require-ment however final approval forthis program has not been obtained. The Universal Turret is electrically powered and has a deSignweight limit of 175 pounds. The basiccomponents of the system (figure 2) are the turret, linked feedsystem and three electronics

OCTOBER 1979

PROPOSED UNIVERSALlOGIC CONTROL BOX

boxes containing the turret, gunand logic controls.In the AH-1 S, the UniversalTurret fires through 110 degrees forward azimuth and has avariable elevation of 20.5 de grees maximum and a depression of 50 degrees maximum.Turret position is controlled bythe pilot or copilot through helmet sights or by the copilotthrough use of the TelescopicSight Unit (TSU) of the missilesubsystem. The turret is electrically driven by two servomotors-one for azimuth andone for elevation. The motorsreceive position commands fromeither the TSU or helmet sightsand feature quick response andsafe, reliable operation.

s previously indicated the uni-versal turret will accommodateeither the 20 mm M197 Vulcan ora 30 mm weapon. The saddle of theturret is designed to accommodatea 30 mm weapon and the quick

release pin mountings of the M197.The ammunition storage containeris designed to hold either 20 mm or30 mm ammunition. Partitionswill be added to the container toaccommodate the shorter 20mm round. Ammunition chutingis easily exchanged by usingquick release fasteners. Theoperation of interchanging gunchuting and feed systems takes lessthan 30 minutes.

The M197 20 mm gun isshown in figure 3 mounted onthe universal turret with its ammunition container. I t firesstandard M50 series 20 mmommunition at a rate of 730- 50 shots-per-minute with aneffective range of 2,000 meters.For the AH-1 S, the gun is heldwithin the turret by a rear ballmount, a slider, and a low forcerecoil adapter. The low force recoil adapter reduces the recurring peak recoil load of the gunto about 1,150 pounds.

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TURR T ~ ~ I J ~ [ ] ~ T R [ ] L SOn the AH-l S, the turret ismounted under the nose of the

helicopter, the same as the present M28 turret. The turret contains the components necessaryfor positioning and firing the gunas directed by the gunner from thesighting station. Positioning ofthe gun is performed by a gimbaland a saddle which moves the gunin azimuth and elevation respectively The azimuth and elevationdrives are powered by direct current motors through gear reductions. Electrical current for themotors is controlled from theservo amplifiers, located in theturret control box, which use thehelicopter s 28 volt DC (direct current) power source.

The turret, gun and universallogic control boxes provide theelectronics for all controls andswitches in the system.

OCTOBER 1979

2Gll :11 :1 L ~ ~ K E I JS T ] R ~ I J E ~ ~ I J f IJ SYSTEI :1

complement of 75 2 mmrounds of linked ammunition isfed to the gun through flexible chut-ing from the ammunition box storedin the ammunition compartment ofthe helicopter. During firing, asmall booster motor pulls linkedammunition from the box andpushes it into a section of flexi-ble chuting which is connectedto the gun s feeder. The boostereliminates excessive belt pullloads, which occur when the beltis pulled on by the delinkingfeeder, and eliminates the requirement to manually fill thechute during loading.

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The 2.75 inch rocket subsystem has been one of the primaryaerial weapon systems used onthe Cobra. It provided valuablesupport to ground units duringthe Vietnam conflict.

There are several developmentprograms that have been initiated by the 2.75 Inch RocketProject Manager to improve thewarheads and launchers to beused on the modernized Cobra.The basic 2.75 inch rocketmotor and the available warheads are shown in figure 4 Thesubmunitions and chaff warheads are the newest developments in the warhead program.

During the SSG review in1974-5, the weight of any prospective improvement was a keyconsideration in structuring themodernized Cobra program. Asa result of the weight factor , arequirement for lightweight 7and 19 round launcher development was established. The design features of these launchersare illustrated in figures 5 and 6

The Stores Management/Remote Set Fuzing Subsystem developed and manufactured byBaldwin Electronics Incorporated, Little Rock, AR, will usethe 2.75 inch warhead and

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launcher improvements to ena ble more effective mission ac complishment by Cobra crews.To date provisions only have beenprovided for this subsystem on thenew production aircraft. It is scheduled to be installed on the 99thnew production modernized AH-1Sto be delivered in November 1979.

The control panel for thestores management/ remote setfuzing subsystem is shown infigure 7. The panel will providethe means to select and fire, whilein flight , anyone of five types ofexternal rocket stores. It will allow the pilot to set range andselect the fuze setting best suitedto the type target being engagedto include settings which will permit penetration of tree canopiesor fortifications protectingselected targets.

Although electrical power requirements for the AH-1 S continue to increase, a

Army Aviation Digest - Oct 1979

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