Army Aviation Digest - Oct 1969

8/12/2019 Army Aviation Digest - Oct 1969

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USAARlSCI SUPPORT CENTER

O BOX 620577FORT RUCKER Al 36362 0577

UNITED ST TES ARMY OCTOBER 96VIATION GES


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UNITED

DIRECTOR OF ARMY AVIATION ACSFORDEPARTMENT OF THE ARMY

MG John L Klingenhagen

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COMMANDANT U. S . ARMY AVIATION SCHOOLMG Delk M. Oden

ASST COMDT U. S. ARMY AVIATION SCHOOLCOL Bill G . Smith

DIGEST EDITORIAL STAFFlTC Robert E. luckenbill , ChiefRichard K. Tierney, EditorWilliam H. SmithJoe Lewelslinda McGowan

GRAPHIC A RT SUPPORTHa ro ld G. LinnHarry A. PickelDorothy L CrowleyAngela A. Akin

DIRECTOR, U. S. ARMY BOARD FOR AVIATIONACCIDENT RESEARCH

COL Eugene B. Conrad

USABAAR PUBLICATIONS AND GRAPHICS DIVPierce L Wiggin ChiefWilliam E. CarterJack DeLoneyTed Ko ntosCharles MobiusMary W. Windham

VIATiONDGES r

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RMY VI TION

1GESJOCTOBER 1969 VO LUM E 15 NUMB E

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VIEWS FROM READERSGANG TACKLING THE VC LT John F. LammSMOKE-A TACTICAL CONCEPT, MAJ Matthew R. KambrodALL BUT FOUR, MAJ. Allan L. SmithROSE COLORED GLASSES, MAJ Nicholas E. BarrecaWHAT IS PWD? Charlie MartinTHE DEADLIEST ENEMY, CPT Charles C. McCloskey IIIATTACK HELICOPTER PILOTS . ATTEN-HUTCPT Milton J. BrokawCHARLIE AND DANNY S WRITEINTORQUE: THE WHYFORS AND HOWFORSLTC Charles W. SillsARADMACS 8TH ANNIVERSARY, COL Luther G. JonesCRASH SENSE-WEIGHT AND BALANCE SENSEMAJ Chester GoolrickPEARL SMIRACLE AT FORT BASTILLE, Ted KontosUSAASO SEZ

36 ARMY AVIATION AIDS CAMILLE VICTIMS Inside

The mission of the U. S. ARMY AVIATION DIGEST is to provide information of an operationa lor functional nature concerning safety and aircraft accident prevention trainin9 mainte hance,operations research and development aviation medicine and other related data .The DIGEST is an official Department of the Army periodical published monthly under thesupervision of the Commandant U: S. Army Aviation School. Views expressed here in are notnecessar il y those of Department of the Army or the U. S. Army Aviation School. Photos areU. S. Army unless otherwise specified. Material may be reprinted prov ided credit is given to theDIGEST and to the author , unless otherw ise indicated .Articles, photos, and items of interest on Army aviation are invited. Direct communication isauthorized to : Editor, U. S. Army Aviation Digest, Fort Rucke r, Ala . 36360 .Use of funds for printing th is publication has been approved by Headquarters D.partm.ntof the Army, 3 November 1967.Active Army units receive distr ibution under the pinpoint distribution system as outlin.d inAR 310-1. Compl. t. DA Form 12-4 and send directly to CO AG Publications C.nt.r 2800Eastern Boulevard, Baltimore , Md . 21220. For any change in distribution requir.ments, initiate arevised DA Form 12-4.National Guard and Army Reserve units submit requirements through their Stat. adjutantsgen.ral and U. S. Army Corps command.rs respectiv.ly.For those not . ligible for official d istribution or who desire personal copies of the DIGEST,paid subscriptions 4 .50 domestic and 5 .50 overseas are available from the Superintendent ofDocuments, U. S. Government Printing Office Washington D. C. 20402.


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anemerge from the C U l ~ l U l t n V f ~ O f r : :and disi:lDOear

slid over the and lowof K 47 fire flashehe told

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Reacting instantly, the LOH returned fire and hopped nimbly outof the way, calling in the twoAH-IG Cobras poised high abovewaiting to strike. At the call, theshark-like helicopters attacked,raking the area with minigun androcket fire.Simultaneously, five kilometersto the east, an infantry companyof the 9th Infantry Division was inan Eagle flight. Five slickloadswere on the ground sweeping anintelligence target with no luck.Another five slickloads circlednearby as a ready reaction force.When the call came that theCobras were in contact, the reaction force left its orbiting positionand headed for the new target area.The sweeping element moved to apredetermined rendezvous point towait for extraction and movementto the contact. A few minutes laterthey hit a new landing zone nearthe target area and moved in as ablocking force.This chain of people sniffer,LOHs, Cobras and infantry is partof the first stages of a new and successful combination of classic tactics: reconnaissance and encirclement.

The new methods, known in the9th Divas Jitterbug and Sealoperations, have virtually shatteredthe grip of the Viet Cong (VC)main force units on the people inthe northern Delta.Such a combination was neededto overcome major problems neverencountered daily by Americanforces. Not only did they face anelusive guerrilla force, but some ofthe world's toughest terrain-thatof the Mekong Delta.Mud in the Delta is a slimy,sucking, unforgiving trap for theinfantryman. It holds him fastwhen he has to move. It fouls hisequipment and quickly saps hisstrength.The water that brings the mud isequally damaging. Besides beinguncomfortable to work in constant-

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ly, it breeds a skin disease calleddermatophysis. Combined with immersion foot, this fungal diseasecan incapacitate a man with alarming speed. The fast-paced airmobile tactics eliminate such constantexposure to water.The Delta also poses a fire control problem because of the highpopulation density, and commanders must be skilled and alert toavoid injuring civilians. They mustremember, however, that the VCcan easily blend with the civilianpopUlation.For all the problems it causes ,the clear, flat Delta region has onemajor asset as far as Seal operations are concerned. It can be described as one huge landing zone,making it possible for commandersto quickly hop troops from onearea to another and to place thesoldiers exactly where needed.The ultimate result is localizingthe VC in streamlines and patchesof nipapalm. It confines them to adefinite area which can be pinpointed and surrounded.Colonel Henry E. Emerson,former 1st Brigade commanderand innovator of Jitterbug and Sealtactics used in the Delta, explainedthe advantage of his methods, tgives us the capability of trappingthe VC and then pounding him. Ii

takes a lot of practice and coordnation, but it ultimately enables uto find and annihilate an entirbattalion.When initial contact is made bthe ground troops, the first step othe Seal process begins. Trying tdraw the VC into a fight, thgrDund troDps have to help the batalion commander determine thexact size of the VC force.The presence of automatweapons is an excellent benchmark. These weapons are usuallfound in units Df at least squasize, and i f there is a squad icDntact the chances are good theris a larger unit in the tree line onearby.N ext, the second set of slickmoves into position on what appears to be the best lane of escapfor the enemy. In nearby battaliobasecamps, standby and evestanding down soldiers are fillinmagazines and canteens and checking radios.By now, the brigade commandeis also circling overhead and usually determines whether or not tmuster the rest of the brigade foa pile-on. f he says go all helcopters available are pressed intservice and troops are poured intthe area.As they come in, the brigad

ir scoop nd hose (arrows) on a sniffer ship


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commander first cuts off the avenues of escape and then fills thegaps in between. f soldiers are notreadily available, artillery and gunships are used to keep the VC offthese lanes.f the encirclement begins in the

latter part of the day, this can, andhas, meant soldiers advancing ontree lines far into the night.Each slickload lands far enoughfrom the contact area to keep thetroops from being brought intocontact before they can spread outalong the perimeter and ill theirgap.While the Seal is taking shape,artillery and air strikes begin.Guided by a forward air controller,the jets pinpoint their bombs on

the entrapped enemy.When all companies are in andthe Seal begins to tighten, bombardment with tactical air becomesmore difficult. Often the circle isjust too tight to call in air strikeswithout endangering the troops andartillery alone does the pounding.When it gets that tight, the supporting batteries have to registertube by tube. In many cases thecommander of the supporting artillery battalion personally calls theshots.The C-47 flareships are called inwhen it gets dark to make it easierto adjust artillery and to preventthe VC from slipping through anyholes that might result i the Sealis not complete by nightfall. Illumination continues throughout thenight.As the encirclement progressesand the ring tightens, the brigadecommander periodically pauses inthe bombardment and offers thetrapped enemy the chance tosurrender. Using both hand-heldbullhorns and helicopter-mountedI,OOO-watt loudspeakers, Vietnamese interpreters and Tiger Scouts9th Divisions name for a Kit Carson Scout) explain to the VC thatthey are completely cut off and tocontinue means sure death.

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A \\snif fer machine mounted in the center o a Huey

Throughout the night, as parachute flares lazily drift down fromthe flareship, the infantrymen leanagainst the slimy rice paddy dikeswatching for any possible escapeattempt. Concertina wire is suspended across streams from a ropeand secured on both sides by engineering stakes.At sunup the companies beginan organized sweep of the area. Inmany cases it is only to countbodies. Other times they may meetscattered resistance from a bunkerthat has somehow escaped thehundreds of rounds of artillery thathave been dumped into the doughnut hole. Sometimes the enemy willstumble out to surrender, the willto fight gone.This may end it. The troops mayload on slicks or CH-47 A Chinooks and head back to their basecamp. f the action took place neara village and buildings were damaged, the brigade psychologicaloperations officer may be theremaking on-the-spot payments fordamaged homes, dead livestock ormissing rice, regardless of how thedamage occurred.In some cases only part of anenemy unit has been caught andthe escape trails of the larger unitcan be found and followed. f so,the brigade will probably begin

chasing the enemy. In some cases,such as the battles in the Plain ofReeds and northeast of Tan An,the chase can go on for four or fivedays before enemy units are finallytrapped and virtually eliminated.Like any precision operation theencirclement requires a lot of experience-and some luck. One ofthe classic examples of the Sealoperation is the battle in the Plainof Reeds.Only an occasional canal orsmall tree line break can be seenon the vast, flat area known as thePlain of Reeds. For years it was ahaven for the VC, but now it isnothing but miles of stagnant waterand rotting vegetation.

The 1st brigade s 2nd Battalion,39th Infantry hit a hot landingzone, 1 June and started an encirclement and chase that set apattern for future operations.For four days the brigade pursued three major VC units, finallytrapping them in a tree line on thesouthern edge of the plain.The 2nd Battalion, 39th Infantry along with the 2nd Battalion,60th Infantry; 4th Battalion, 47thInfantry; and Vietnamese CivilianIrregular Defense Group soldierssurrounded the VC and killed 192enemy bringing their three-daytotal to 233.

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airmobile force, the suspectedenemy location and on thearea the ground commanderand the air mission commanderdesired screened, they wouldreturn to the release point andorbit while awaiting the troopcarrier aircraft. Upon their arrival the smokeship wouldposition itself abeam the leadship on the approach to theLZ. Coordinating with the gunship leader, the smokeshipwould at this time descend toground level in position for thesmoke run. Timed iust ahead ofthe airmobile assault force andiust behind the leading gunshipescort, the smokeship wouldlay the smoke screen.

When the smokeship wasemployed in four early operations in areas where the battalion had habitually drawnheavy fire, the airmobile forcedid not once report receivingfire.However in one operation,due to a lack of intelligenceand unsatisfactory wind conditions, smoke was not utilizedas effectively as it might havebeen. n this instance fire wasreceived from the unscreenedside of the landing zone. It isfelt that due to the width of theLZ the smokeship should havesealed both sides of the landing area. This was realized toolate, however, but was henceforth given full considerationin all operations with similarexisting conditions.

The employment of thesmokeship was further explored by a ground commanderas a diversionary tactic. Sup-OCTOBER 1969

porting the 1st Brigade, 25thInfantry Division, the smokeship could not be practicallyutilized in the assault phase ofthe airmobile plan due to unsatisfactory wind conditions. Toinsure full use of all his available resources, the ground commander requested that thesmoke aircraft be used in adiversionary role by sealingthe periphery of a town on theapproach course of the inboundairmobile force. The primaryintent was to divert the attention of the enemy, thus creating the question of the exactlocation of the landing zone.Not only was this accomplished ,but also, by hampering thevision of the enemy forcespositioned along tree lines surrounding the hamlet on theapproach course, the smokeship very effectively affordedadded security to the entireflight.

Again, on an operation supporting the 1st Brigade, 25thInfantry Division, the smokeship, in coniunction with gunship teams from the 116th As-sault Helicopter Company, wasused most effectively in thesupport of ground troops in thewestern zone of the brigade sarea of operation.A battalion from the 1st Bri-gade was air landed parallelto a north-south tree linethrough which the unit was toadvance to the east to conducta search and destroy operationthrough two wooded areas.The first heavily wooded areaextended 1,500 meters to theeast, after which a clear area,

rectangular in shape, runningnorth and south approximately900 meters wide, was located.The infantry moved to the eastedge of the first wooded areaand halted.

At this time the 116th s gunships made a suppressive runfrom north to south down thecenterline of the open area.The smokeship, on the deck,made its first pass immediatelybehind the gunships. A wall ofsmoke now separated the in-fantry from Viet Cong elementsoccupying the tree line to theeast, the second obiective ofthe infantry battalion.

The infantry rapidly advanced to the smoke anddropped behind a series of 2-foot rice dikes. Before thesmoke could dissipate the gunships attacked the far tree line,the infantry s second obiective.The smokeship made a secondrun, again from north to southand behind the guns, on thewestern edge of the secondtree line. Sealed again by asolid layer of white smoke, theinfantry advanced and reachedthe next wood line, never onceaffording the enemy the luxuryof a point target. With no significant resistance the groundforces were able to close withand destroy the enemy.

Given free rein on many assaults conducted in support ofunits frequently worked with,smoke pilots developed numerous techniques for employingthe aircraft. Frequently thesmokeship, approaching thelanding zone from a directionopposite to the final inboundheading of the liftships, wouldsmoke the downwind side ofthe LZ seal the rear of theflight and continue the screening of the upwind side as theslicks pulled pitch. This r s ~ -shoe technique proved highlyeffective, especially in opera-

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Smoke A Tactical oncepttions wherein infantry forceswere being extracted from hotLZs. In such situations coordination and timing were absolutely essential to avoid havingthe smokeship inadvertentlyshot up by aggressive doorgunners laying down suppressive fires.As smoke operations continued to develop, the smokeship became so much a part ofinfantry assault helicopter operations that the aircraft wascontinuously requested to support air assaults throughout thecorps area and figured substantially in ground commanders operations orders. So suc-cessful had the concept becomethat smoke pilots were loggingin excess of 100 hours eachmonth. The aircraft s daily itinerary consisted of continuousshuttling from the landingzones of one operational areato those of another.

The smokeship, however effective in combat assaults, trulyendeared itself to the infantrymen in medical evacuation operations. Soldiers wounded onan LZ or in any operational

area were afforded a moresecure evacuation when thesmokeship was available toscreen the LZ to hide the Dust-off inbound for the pickup.Dustoff pilots also were mostappreciative of the servicesrendered.

Within four months of operation, the techniques for employment of the smoke aircraft wereestablished. Unquestionably,prime consideration had to begiven to wind direction andvelocity. The importance of thiscertainly will be confirmed byanyone who might have beeninvolved in the few early occasions when a miscalculationsuddenly rendered the LZ IFR

Altitude and airspeeds werealso critical in effective smokeoperations. Smoke runs above20 feet absolute and in excessof 100 knots were found to beunsatisfactory. Winds coupledwith the limited smoke densitycaused by a high airspeed leftthe mission almost ineffective.The most benefit was derivedfrom a run made as close tothe ground or trees as safetywould permit and at approxi-

/mately 80 knots. This techniqueguaranteed that the smokedensity was sufficient to preclude its dissipation for t least1 5 to 20 seconds, the ti me required to clear an LZ

Especially effective was theemployment of smoke alongcanals and river banks, frequently the location of VC em placements. The smokeship, fly


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The crew of the 269th Combat AviationBattalion s original smokeship are (fromleft to right> SP5 Paul Geving LTC JamesH. Merryman , MAJ Jack McKnight andSP5 Philip Busby

ing beside the brush growthalong a bank could lay smokeon water where it would be re tained for lengthy periods. Acanal could be smoked downits banks, down its center or a ta given distance from it, depending on the suspectedenemy situation. In each casethe smoke would render thefire received from the gun positions ineffective in that pointtargets were again denied theViet Congo

The principle in the mechanics of smoke emission are quitesimple. Two 55-gallon bladdersare laid parallel across thefloor of a UH-l C The bladdersare filled with fog oil, a petroleum composite similar to 10-weight motor oil. The fog oilis pumped through tubing to ametal ring emplaced around thecircumference of the aircraft sexhaust. As the oil is pumpedto the ring its flow continues

through iets into the intenseheat of the exhaust gases. Theoil is vaporized immediatelyand smoke billows to the rearof the ship.As the rear bladder empties,the auxiliary fuel pump switchis activated, transferring thefog oil from the front to therear tank. The entire load ofoil on board provides approximately eight minutes of smokeemission. Eight minutes is a

considerable amount of timeconsidering the brief time spanrequired to run an average LZin the III Corps area.

The smokeship is a relativelynew product of Army aviation scounterinsurgency role in Vietnam. After many months ofcontinuous operations, thesmokeship concept is beyondany doubt a success and an immeasurable asset in conductingcombat assault operations.

The smoke generator consists of a circular tube of small jets (arrow) fitted around the exhaust

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llBut Fourrolling in from the west. Theyseemed a long distance away butstretched s far as the eye couldsee to the north and south . Theops officer advised the troop com-mander of the situation and thathe probably would need relief onstation. The CO replied that hewas just preparing to depart basecamp for the extraction site.The gunships were very low overthe patrol. Slightly above the gunsthe two slicks droned in orbit. Awhisp of yellow smoke filteredthrough the foliage and quicklyboiled away downwind s the pa-trol marked its position. t h dmoved only about 50 meters butwas on course to the LZ.The sky began to darken and inthe high winds the guns had diffi-culty staying accurately on station.As the CO arrived he asked thepatrol to mark its position again.With darkness closing in the smokewas barely discernable but re-vealed that the patrol was stillabout 150 meters from the LZ.The patrol leader told the COthat he thought they were beingfollowed and requested extractionfrom their present position. TheCO decided there was no alterna-tive and ordered the first ship infor an extraction.As the first slick settled carefullyinto position above the thrashingtreetops the gun team requestedrelief. The relieving fire team hadjust departed the base camp and thealert team rapidly briefed its leaders the two teams passed enroute.The relieved alert team arrived atthe base camp s the first rain be-gan to fall. It was the last flight toget back unassistedThe long nylon ropes wereT ey clung tightly to the ropes s they

cle red the trees nd r in beg n to pelttheir f ces12


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dropped through the trees to thesix men. Every foot of rope wasused before the rigs reached theground as the ship hovered 5 to2 feet above the jungle roof. Theextraction orders to the patrol werethat only two men would be liftedby each ship and there would bethree lifts.

The first two patrol memberslooked anxiously up in the dark-ness as they felt the tug of the lift-ship. They clung tightly to theropes as they cleared the trees andrain began to pelt their faces. Theywere quickly taken to a nearby firesupport base and gently set down.Already the second liftship wasover the patrol and began to lowerthe ropes. Once again the orderswere sent to the patrol, only twomen on this lift also.The crews were now operatingin almost total darkness. The ten-sion was high, both in the air andon the ground. To the patrol mem-bers the minute or two that elapsedbetween the first and second lift-ships seemed an eternity. The windand rain were so loud that a heli-copter could be heard only whenhovering directly overhead. Thefour men began to sense a feelingof total isolation. When the ropeslowly settled down to them allfour hooked up. They gave the sig-nal to go.Meanwhile the winds had reached20 knots, gusting to 40. The hover-ing helicopter slowly began to rise.The load came up about 10 feetwhen the ship began to roll intothe load. There was no communi-cation possible with the soldiersdangling below.

The cyclic control was nearingits lateral stop as the aircraft com-mander attempted to level the heli-copter. Then the ship began tosettle sideways into the trees as thelow rpm audio and warning lightcame on. There was nothing to dobut jettison the load

The crewchief started to cut therope. Suddenly, the ship was lifted13


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ll But Fouron a high gust of wind and appeared to leap into the air clearing the trees with its load.

The CO ordered all aircraft toreturn to base camp and stand by.He next directed the extractionship to take the troops to the firesupport base. The first liftship onits way back from dropping off itsload turned toward the base campand reported going into cloudsthen went silent.

At this moment the relief gunteam leader was heard to tell hiswing man to execute an immediate1 SO-degree tum and return to basecamp. The gun leader informed theCO that he had also inadvertentlygone into instrument flight conditions and was attempting to makea lS0-degree tum to VFR condi-

tions. The CO advised him toreport when VFR or if he encountered any further difficulty.Back at the base camp thetroop maintenance officer had beenorbiting over the runway while hemonitored the progress of the extraction on the radio. He gave thelone wing man an FM steer andthe gunship managed to find thecamp. The CO also reque ted anFM steer but gusty winds madeaccurate navigation difficult. Providentially the storm subsided for afew seconds and the maintenanceofficer saw a helicopter passing tothe east of base camp on a southerly heading. The CO was told toturn to a heading of 270 degrees.In a few minutes he arrived overthe runway. wo down and threeto go

The extraction ship reported thathe was safely down in the fire sup-

he tr nsient elected to depart despite the severe weather warning

port base but two of the patrmembers were injured and twothers had fallen off into the treeThe slick was ordered to remainthe fire base until the weathcleared. hree down and two to gThe lost gunship had turned tward a nearby Vietnamese townwhich a Military Assistance Command Vietnam MACV) airfiewas located. When the ship failto fly into clear air the aircrcommander climbed to 4 500 fefor terrain clearance and continutoward the town. The aircraft commander began to experience tfirst uneasy symptoms of spatdisorientation. The fact that histitude indicator was 5 degrees oin the roll attitude was not helpimatters. Just as his aircraft contrbegan to get erratic he saw tclouds open up and down below the rain the crew could see ligh


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He orbited the lights a few timesto confirm his position over theMACV installation. Then hespiraled down through the hole.The spiral with its high rate of turnand unusual attitude began to effect both pilots. The only referenceoutside the aircraft was the fadinglights which appeared at a crazyangle out the right door.

In this confused condition theclouds swallowed them up again.The aircraft commander had directed the copilot to take the controls as the spiral began for fearthat if the aircraft did enter theclouds again he would lose controlcompletely. Somehow the copilotgot the ship level and climbing.The crew decided to get help andturned for an Air Force base to thewest. That was where the nearestGCA was located.At the base camp the maintenance officer was still airborne ashe vainly tried to contact the twolost ships. Suddenly, to his amazement, he heard a transient maintenance ship call the base camptower for takeoff. The maintenanceofficer advised the transient thatthe winds were gusting from 20 to40 knots, the visibility was less

than mile and the ceiling wasobscured with heavy rains in allquadrants.The transient reaffirmed his decision to depart and remarked thathe only had a 15-minute flight tohis home base to the west. Onceagain the airborne maintenanceofficer asked the transient to reconsider and added that there already were two ships lost in theheavy rain clouds.The transient replied, "Thanksfor the information, but I think Ican make it."There were four people onboardthe transient as it departed to thewest. Immediately the rain andclouds seemed to snuff out the departing aircraft's navigation lights.

The gunship heading for the AirForce base GCAhad been fiyingOCTOBER 1969

for 20 minutes at 6,000 feet andwas still in the l o u s The aircraftcommander had beep trying to contact the air base on all possiblefrequencies including guard. Hefinally managed to get the Armyheliport adjacent to the air baseand was told GCA was standing byon its primary frequency. For another five minutes he attempted tocontact GCA to no avail. Heswitched back to the heliport frequency and was just about to -callagain when the ship broke out ofthe clouds into a very large hole.Almost directly below was a basecamp.The crew decided the camp wasthe division base to the west andbegan a rapid descent. The aircraftcommander advised the heliport atthe airbase that he was landing atthe division camp. While descending, he was reminded of the earlieraborted descent. This time thelights stayed in sight and as theaircraft was rolled out on final approach he could not believe hiseyes'-he was landing at his ownbase camp He had flown 25 minutes on a westerly heading and hadgone three miles to the west andeight miles south. Four dawn andone to go.Troop operations was still tryingto contact the lost slick. The Dmodel had been flying for twohours and fuel was getting critical.The slick, at that moment, alsohad been flying west for some time.The pilot was having little difficultywith aircraft control at 7,000 feet,but had no idea of his position.When the indicated fuel remainingreached 300 pounds the aircraftcommander began to transmit adistress call on guard to Paris radarcontrol. Paris finally heard theship, but could not locate it. Paristhen advised that the weatherseemed to be improving on thecoast.The pilot turned south in a lastattempt to reach clear air. Radarbegan to cOncentrate its search to

the south and east. A weak targetwas located on a bearing of 130degrees at a range of 48 miles.That couldn t be the chopper outto sea?In desperation the radar operator called the ship, I have a possi

b e target 48 miles to the southeast. For radar identification tumright to 330 degrees."Slowly but surely the targetturned to the assigned heading thenfaded off the scope.Pa-ris quickly advised the shipthat radar contact was lost, but tomaintain a heading of 330 degrees.The pilot replied that he wasleaving 7,000 feet in a final descentwith 160 pounds of fuel indicated.Paris control could do nothingmore but advise air sea rescue ofthe ship's last known position andheading.As the slick descended the copilot stared into the red and greencurtain of cloud in front of thewindshield. Suddenly the red andgreen glare vanished and below hesaw snow No, not snow, but whitecaps. The shock passed instantlyas he saw the white line of surfpounding the beach just ahead. Alast call was made to Paris to report that they were landing on abeach. There was no reply. As theship settled onto the sand morerain obscured a dim light in thedistance. The engine was shutdown with two hours and 35 minutes flight time and 60 pounds offuel indicated. The wait began.A few hundred meters away ayoung RVN MP walking a guardpost in his company's bivouac position heard the unmistakable beat ofhelicopter blades. He peered toward the beach where -the soundseemed to originate. The soundshad been low as if a helicopter hadlanded, but now he could hearnothing except the wind and surf.He did not think a chopper wouldbe out in such weather. Still, hisorders were to report anything un-usual, so he sent word to his cap-

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ll But Fourtain that a helicopter may havelanded on the beach. The captainquickly aroused his Americancounterpart and with a few menthey headed for the beach.

the downed ship gave the magneticbearing from them to the rotatingbeacon light and requested fuel. ACH 47 Chinook, already alerted tothe downed aircraft, was soon onits way.

and it is now landing safely at tcoastal field) with all hands. FidownJust then the telephone rang.was the CO of a unit to the weasking about his maintenance shand its crew. He was informed the transient's hasty departuhours earlier in the storm. The Casked air troop operations to assin a search the following morninbut the trQop was able to p r o v ivery little assistance because it sthad a search of its own to conduc

On the beach the crewmen hadposted security and their immensesense of relief over a safe landingwas slowly replaced with anxietyover the security of their position.The rain subsided again and thelight in the distance began to winkagain. White, dark, white, darkagain green. t had to be an airfield.

As the aircraft commanderturned his radio off he heard thebooming voice of his crewchiefposted on flank security, Halt,who goes there?A cheerful American accent replied, H e y man, we're friendlypolicemen out looking for youguys. 'Need any help? The two missing LRRP patrmembers were found the next dafter an extensive air and g r o ~search. The patrol leader, wslightly injured but both had suvived the wild ride through ttrees and a full day alone in unsecure area.

The aircraft commander crawledinto the ship and called the towerat the only airfield he could thinkof in such proximity to the beach.The tower immediately replied and

Gratefully the crew greeted thesmiling Vietnamese MP patrol andthe U. S. advisor. The MPs set upa perimeter and soon the Chinookarrived with the needed fuel.In ~ i r troop operations a message arrived from air sea rescue,


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The second type sunglasses toavoid are those advertised to automatically or mechanically vary thedarkness of the lenses. Theseglasses, when recently evaluated,were found to be unacceptable forgeneral use. Sunglasses are best ifthey transmit at least 10 to 15 percent of visible light. The variabledarkness glasses, under most conditions, transmit far below 10 percent of the available light. Again,rather a dim situation.These glasses, in addition tomany other glasses available commercially, are optically impure.Many have high degrees of colordistortion as well as excessiveprism (due to improper curvature)to further interfere with vision. Soagain the warning: Seek thoseglasses which have been specificallydesigned to contain the necessaryproperties for optimal optical performance, particularly the glassespurchased to meet military specifications. Remember also, the postexchange is not required to offersunglasses exclusively acceptableto aviators. Accept our standard,not so flashy, wire-rimmed issuesunglasses with a smile of confidence. They are for your protection and definitely should be usedfor the purpose intended.Incidentally, the sunglass visorprovided with your helmet servesa dual purpose. In addition to sunlight protection, it is utilized to decrease the surface area of skin andvaluable visual apparatus exposedto possible flash fires or missile andplexiglass fragmentation which mayoccur during emergency or crashlandings and combat situations. Itcan be most effectively used duringtakeoffs and l n d i n g s ~ Use commonsense, though. f visibility is already restricted, don't restrict itfurther with a sun visor and end upcausing an accident. The clearvisor used in conjunction with sunglasses is a better choice, for it canprovide protection alternatives forday and night flyingOCTOBER 1969

Glasses don't have to be coloredor tinted to create disconcertingproblems. Individuals wearing corrective lenses for distant vision mayparadoxically be at a slight disadvantage while flying at night.The corrective lenses, unless specially treated, only transmit 92percent of incident light. Antireflective coatings can be applied,increasing transmission to 98 percent. Such treatment of lenses provides us with night flying glasses.These glasses do not enhance nightvision magically, they are simplyan improvement over wearing plainglasses, for individuals requiringcorrective lenses.Some pilots, not wishing to admit their failing vision, will findthe rose colored glasses are theirown eyes. Under night circumstances, all of us become relativelynear-sighted due to a shift in thenature of visible light to the blueside. Pilots who are already slightlynear-sighted will become more soat night. Images under these conditions may become indistinct; visionmay be obscured. Aging pilots(those over 30, sorry fellas), par-

ticularly i f far-sighted, may havedifficulty with the red-lighted cockpits. We are all slightly far-sightedfor red light. f far-sighted underdaylight conditions, those of uswith weak accommodation (a notuncommon companion with age)will not be able to compensate forthis red-lighted far-sightedness.Thus, vision will be blurred.Each of these conditions can becorrected by your friendly flightsurgeon, if you put aside pride andungrounded fear. He can prescribe special night flying corrective lenses for each specific condition. These are usually minor problems that do not raise questions ofyour suitability for flying. Don'thesitate to bring them to medicalattention.Finally, remember what CaptainFinkleding-a-ling (cleaning hispipe, while peering quizzicallythrough the moonlighted mist withhis variable purple people peekers) ,said to Major Frozzleforth (whowas puffing billows of smoke fromhis 55th cigarette), Is that a radiotower I see before us? MajorFrozzleforth answered, I don'thear anything.

19


22/68

WH T S

PWDCharlie Martin

ANOTHER JUMBLE of let.l.. ters in the overcrowded jungleof acronyms? Perhaps, but those ofus who have had an opportunity tosee the Proximity Warning DevicePWD) -in actionand to test itdon't think it will be difficult toremember. close proximity and gives the aircrews time to avoid a possiblecollision.

Ft. Rucker, Ala., area took 2lives, 13 aircraft were destroyeand the materiel loss was approxmately 2Y2 million dollars.The PWD has been developed asan aid in the prevention of midaircollisions, and as all aid it maynot provide everything we'd like,such as range and azimuth, but itdoes warn of another aircraft in

Few of us are aware of the tragictoll in life and property of midaircollisions. During the 24 ~ o n t sfrom November 1966 to November1968, seven midair collisions in the

Everything possible has beedone to insure adequate separatioof training aircraft. The plans fotraining areas, air routes and alt

20

Blow, a typical application of the Proximity Warning Device. The helicopter at the center of the protective envelope would bewarned that an intruder is nearby and above. At the same time the aircraft at the right WQuid be cautioned that an aircraftrepresenting a potential collision hazard was below. The intruder s position is indicated by one of three lights on the displaypanel (above) ~I QUAL I[QJ----- ...--- ~

. .- -- ... \- , ,/ ?IS 1-1\ / / / ____ /3 toI / - -----... )\1

t < : ~ ~ ~ = ~ = ~ ~ ~ ~ ~ ~ ~ : : ~ ~ +, ---- : - - - -----------1------------ I.J .II

II

.1.....t--------2000 . . . .U. S ARMY AVIATION DIGES


23/68

Left, TH-13T helicopter installation of the Proximity Warn-ing Device with the panel display mounted on the centerconsole. Right the heart of the system includes the receivertransmitter on the left and two dipole antennas which giveomni-directional range coverage

tude separation are thorough andcomplete, but there will always bethe ever-present potential of humanerror. Someone doesn't get theword, misunderstands instructions,becomes pre-occupied with the jobat hand or simply becomes complacent. These are the things thatthe PWD is designed to overcome.Personnel of the U. S. ArmyAviation Center have been activelyworking on the development of thePWD since 1967. They enlisted theaid of the U S. Army Board forAviation Accident Research, theU. S. Army Electronics Commandand the U. S. Army Aviation TestBoard. The combined efforts ofthese organizations have resulted inthe development, testing and selection of a Proximity Warning Device for use in the training environment.The initial devices are tailoredfor use in the TH-13T helicopters,but will be readily adaptable toother aircraft. Studies (which laterproved to be valid) indicated thatthe device should provide a visualindication and an aural warningwhen another aircraft approachedwithin 2,000 feet horizontally and300 feet vertically. The visual indication was required to showwhether the approaching aircraftwas at an equal, higher or loweraltitude.The technical requirements established by the Electronics Command for a PWD that would produce the desired warnings wereconsidered to be within the existingstate-of-the-art and would not require extensive development, eventhough this was to be an entirelynew device.OCTOBER 1969

The PWD is a cooperative system. That is, each aircraft must beequipped with its own device because, as the developing engineersput it, the PWDs talk to eachother. Each device contains asealed barometric sensor, a receiver and transmitter. The barometricsensor determines the coding of thetransmitted pulses and positions anacceptance gate to permit receivingresponses from only those systemswithin the selected range. f thebarometric sensors are within plusor minus 300 feet vertically andthe pulses are received through theacceptance gate, a warning is generated. The altitude band is furthersubdivided to provide the requiredvisual altitude indications of above,equal and below.Testing of the PWD was a realchallenge; this was a totally newdevice. There was no precedent fortest or employment, and operational techniques were just ideas.Several manufacturers were submitting equipment and time waslimited. The first two weeks was alearning as well as test period and,fortunately, the first PWD playedas advertised and allowed us tolearn as well as test. During thesetwo weeks, I believe we literallyflew at each other from every conceivable angle and from groundlevel to 4,000 feet MSL to checkfor hysteresis of the barometricsensors. We measured the warningrange and time at a sufficient number of relative bearings, altitudesand rates of closure to insure thatthe area covered was, in fact, acylinder approximately 2,000 feetin radius extending 300 feet aboveand below each helicopter. Also

we wanted to be sure that therewere no holes in the cylinder thatan intruder might slip through.The minimum times from initialwarning to potential collision averaged seven to eight seconds forhead-on approaches and autorotations toward a climbing helicopter.We convinced ourselves by aborting collision courses after receivinga warning that there was sufficienttime to find and avoid an intruder.As a final test the PWD equippedhelicopters were assigned to theDepartment of Rotary Wing Training's Basic Instrument TrainingDivision. Two PWDs were scheduled for routine training flights andone was flown by test personnelas a deliberate intruder. I t didn'ttake long to get an indication ofhow this phase of testing would go.Most comments were favorable,along with some warranted constructive criticism.The instructor pilots were quickto recognize the capabilities andlimitations of the PWD. They usedit effectively and are looking forward to the time that all the helicopters in the training environmentare equipped with the PWD.

f all goes well, they won't havelong to wait. Honeywell AerospaceDivision of Minneapolis has beenawarded a $775,711 contract for222 warning devices for use in theTH-13T helicopters located t Ft.Rucker and Hunter Army Airfield.Options in the contract could resultin the purchase of an additional1,293 units for a total contract inexcess of $4.5 million.Installation of the initial orderwill begin in about a month andwill be completed by late spring1970.

21


24/68

THEDEADLIEST I _ _O_R_ED_O_M___IENEMY might as well go down on the deck I mnot doing any good up here I m bored to deathl

THE 0 1 Bird Dog is seensilhouetted against the clearmidday sky of the Republic ofVietnam. The complete master ofits environment, it passes effortlessly across mountain and jungle,river and rice paddy. I t now quickly descends, lower and lower, untilit barely skims the trees. After theaircraft passes out of sight for afew-seconds thick, black smoke isobserved rising where it was lastseen. The aircraft has crashed,killed both occupants and is totallydestroyed. Why?Safety Officer: The aircraft wasflown at a low altitude, approximately 50 feet above the trees, anot uncommon technique for the0 1. TIle pilot s attention evidentlywas distracted, leading him into asituation from which he could notrecover No evidence of hostile fireagainst the aircraft could be found.Flight Surgeon: The pilot wasan experienced combat veteran. Hehad been in the company for 10months, strictly as a pilot, and hadaccumulated over 900 combathours in the 0 1. He had flown

Captain Charles C McCloskey III103 hours in the past 30 days. Ihad seen him three days before hisaccident and found he showed nosigns of fatigue whatsoever. Hehad no complaints and stated hefelt great and wanted to continueflying NeverthelessI medically restricted him from flying for thefollowing day, t r u t i n g him toget a good night s sleep and torelax the next day. He had eatennormally the day of the accidentand had consumed no alcohol inthe previous 24 hours. He hadnoted no emotional problems toeither me or his fellow officers inthe company. I believe there wereno physiological or psychologicalfactors present having a directcausal effect on the accident.

Platoon Leader: The pilot wasone of the best in the platoon, ifnot the best. He had not had anaccident since receiving his wings.He was very skilled at his job,consistently returning from his missions with a great amount of intelligence data and/or reports of numerous enemy killed and structuresdestroyed by air strikes or artillery

he had called in. He was dappointed if he came back frommission with nothing to report. Henjoyed doing his job and togreat pride and satisfaction in ding it well His only drawbacwhich I had counseled him on least twice, was that he flew lolevel to excess. I explained to hithe inherent dangers of flyingthis low altitude and he agreed astated that he would be morecarful. I have no idea what could hahappened to him.Maintenance Officer: All paof the aircraft were recovered evthough heavily damaged by fiThe engine was examined and indications were found of materfailure. The control cables and sufaces were also free of materfailure. It is felt that the aircrawas in normal operating conditiupon impact.Investigating Officer: All avaable evidence points to the fathat the aircraft crashed due pilot error in putting himself inposition from which he could nrecover.

U S ARMY AVIATION DIGES


25/68

The above comments are notuncommon in 0 1 accidents. Butthe reason for the pilot's error hasnot been discovered nor explained.What and where is the reasonwhich caused it to happen? Was itweather, the enemy, materiel, themission, improper supervision,poor training or what? Who orwhat is the deadliest enemy of the0-1 pilot in Vietnam?

Pilot Boy, it sUre has been anothing day so far. Spent thosefirst two hours adjusting artillery.What a waste of time Round andround in circles for 120 straightminutes-and only two registrations completed This whole AO'sbeen dull lately . And thought thisvisual reconnaissance flight mightbe good. There's not a damn thingdown there worth looking at, justrice and trees. Can t see anythingfrom 1,500 feet anyway. And thisobserver I've got How come always get the neW guys? He doesn'teven know how to read a map,much less talk on the radio . . .hey, wait a minute. That nextvalley is where saw those fiveNVA last week. I'll bet there'smore there now. Might as well godown on the deck, I m sure notdoing ariy good .up here. I m boredto death.

And there it is, as plain as anormal takeoff. The deadliestenemy to defeat in flying the 0 1in combat is plain boredom. Thefirst few months, duty as an 0 1pilot will not normally be dull, butafter the newness has worn off, theboredom can very easily set in.There are times when low-levelflight is warranted and justified,e.g., confirmation of ground sightings and evasive action. But thetemptation is t6 fly low level whenthere is no rational or profitablereason for doing so. And the oddsfor surviving any kind of aircraft

m a l f u n c t i o ~ enetp.y hit or abnormal occurrence in flight dropmeteorically at low altitude.OCTOBER 1969

o what is the best way to fightthis often fatal human frailty?First, a mature, professional attitude must be maintained towardmIssIon accomplishment. Eachpilot must understand that he cannot be successful or necessarilysatisfied each and every time heflies a mission.Secondly, boredom can be overcome by self-improvement. Thepilots must learn new lessons andtactics from reference manuals,from articles and publications andfrom other pilots. He must improvehis skill within sensible safetylimits. He must not lower theselimits to obtain success, for he thenendangers his life and the lives ofothers.Next, he can develop teamworkin the aircraft, so that the man inthe back seat does contributesomething to mission o ~ p l i s h -ment. True, some o b s e r v ~ r s arebetter than others, but with patience and perseverance an effective and successful team can be-

come a reality. Perhaps not on thisflight, nor this day, nor ever withthe same pilot, but none the less aneffective team some day in thefuture, working together professionally to accomplish the mission,scaling out the hazards of boredom.And last, the pilot must keep inmind the responsibility he has toothers-his wife, his family, friends

and relatives, his fellow pilots, hisunit, his country. He, as an individual, is of great importance tothese people and groups of people.Does he have the right to unnecessarily risk lives to merely break hisboredom? Even with an unsatisfiedego and a high degree of selflessness the answer is no.So chalk up the above accidentto pilot error, combat loss or whathave you. Regardless, the underlying factor was boredom. It is notunusual among 0 1 pilots, or allpilots for that matter, but it is adangerous aerial trait which mustbe avoided. Save your boredom forthat 17 -hour flight home-and h u ~insure you do make the flight.

23


26/68

Attack Helicopter Pilots

. T'tten . UAlthough the 2.7S-inch rocket and the 40 mm grenade have bad proximity fuzes formore than a ye3l', very few units are using them effectivelyCciptain Milton J. Brokaw

TH VALUE of the .attack_ helicopter has .been proventime after time in the Republic ofVietnam. As an experienced attackhelicopter pilot, I want to speak toll the aviation and. ground personnel who are iIfterested in increasing the fire support these helicopters are capable of giving. Allof us have been looking for methods to increase their effectivenessand, as a result, such things as newor improved tactics have evplved.Also, new aircraft have been designed with better performancecharacteristics.

result, tremendous breakthroughshave been accomplished. One sucharea concerns the fuze d e v i ~ s forthe 2.7 5-inch rocket and the 40mm grenade.

Emphasis on training attack helicopter pilots at Ft. Rucker, Ala.,and Ft. StewaI1, Ga., has increasedto the point where these pilots arenow learning as many of the fundamentals of attack helicopter em- \ploymeilt as they possibly can inthe time allotted. There remains onearea where a sigumcant increase ineffectiveness is possible. This areais in the weapons themselves. Quitea few people have been concernedwith this particular prob1em. As a

The proximity fuze can mean the end tothe Viet Cong's seemingly charmed life.This closeup view demoilstates how the2.75-inch rocket can effectively putsmoke on Charlie

How mariy times have we all

seen or heard about the Charliwith the charmed life ? We hafired rockets and 4b . grenadarid have seen die impacts around him omy to fihd that whthe smoke clears he was still ru

24 U. S. ARMY AVIATION DIGES


27/68

ning, ~ p p a r e n t 1 y unhurt. The s a m ~thing has occurred with the "Cparlie" that you can dearly see s n u ggled down behin i that d i k ~ but\ v h o ~ you just can't seem to hit.Your immediate reaction is thatthese ,"darn" rounds are no good.The 'reason for this ineffectivenessis simple. In many types of terrain,especially soft < >r wet, the roundswith point d e t ~ n ~ t i n g (PD) fuzesactually penetrate into the m ~ dwater, ground, etc., before t h ~ y explode. As a result, a large portion ofthe fragmeQts and e x p l o ~ i v e poweris ~ o n t a i n e d underground and muchof the rest directed upward andcauses no damage whatsoever.What is the answer to this p ~ o b -lem? The answer is the prqximityfuze, whiGll will get those lethalfragments down b e h i ~ d that log ordike or down into that foxhole.This will end the 'days of ' the

OCTOBER 1969

"charmed life Charlie."It has long been known that byplacing a properly designed proximity fuze on a high explosive warhead you can increase the lethalarea anywhere from three to 10times and even more in certain special cases. The problem has beento provide a r e l i a b l ~ proximity fllzeat a relatively low cost. Unfortunately, some of the older fuzes thathave been stock-piled from WorldWar and Korea have not beenable to withstand long-time storage,and their reliability is sQmewhatless than desirable. New d e v ~ l o p -ments in the state-of-the-art havechanged this. Today's solid statecomponents and circuitry allow usto build small, reliable, low costproximity fuzes. The M429 proximity fuze for the 2.75-inch rocketis the first of these new fuzes to beisslJ ed. When understood and properly employed, this proximity fuzecan literally multiply effective firepower.Now I come to the very heart ofthe message. The M429 fuze hasbeen in the fielp for about a year.Tremendous effort has been putforth in order to get this moreeffective weapon into the hands of

the troops. However, it has becomeapparent that for various reasonsthere is some reluctance to use thisitem. The reasons stated ~ n g e anywhere from I can't get them'" to"The terraip. in my area isn't rightfor this weapon." When you showthe reluctant ones that they arewrong on both counts, then theyusually come up with the actualreason: "Well, to tell the truth, Idon't really know much aboutthese new proximity fuzes. The oldPD fuzes still work, don't they?And, besides, I have heard STORIES that. "One such "story" was related bya pilot who swore that he had beenhit by a fragment from a VT f u z ~ drocket which had exploded in frgntof his aircraft. It turned out t ~ a ta proximity fuze for the 2.7 i n c h

rocket hadn't even been producedat the time of the incident. Afterbeing informed of this, he readilyadmitted that he had just assumedit was a proximity fuze since itdetonated in the air. The harmdone by that story and qtherstories of a similar nature is tremendously difficult to overcomeand seriously hampers the a ~ c e p t -ance of a new, more effective item.Let me now explain a little aboutthe capabilities and characteristicsof the M429 proximity fuze for the2.75-inch rocket. In general it iseasy to understand. f you don'tworry about the engineering details, the M429 is simply a radiotransmitter and receiver. I t bouncesnidio signals off the target andmeasures how strong the returnsignal is; and, when the signal isstrong enough to indicate the presence of the target (at the desiredheight of burst), it detonates thewarhead. It carries its own battery

f ~ r electric power and a safety anda:rming device. The safety deviceassures you that unless the roundproperly launched and travels as'afe distance, the fuze will dud.This safety and aqning (8 A)device is a standard requirementfor all fuzes induding the pointdetonating type. In addition, thereis an impact element indudedin the M429 so that if the radioportion fails, the round will stillfllnction when it strikes the grQund.All of the above parts must worktogether in the proper s e q ~ e n c e .\Vhen the fuze is a t t ~ c h e d to arocket and fired, it must tum itselfon, warm up in a fraction of a second and perform flawlessly underextreme conditions of temperatureand humidity. Even before this, ithas to survive shipping around theworld by rail, ship and airdrop. Inaddition to being just plain safeand rugged, it must have specialcircuits that make it smart enoughto see the ground but npt the roundin front or in back the rockettraveling alongside, and it must not

25


28/68

be confused by local radio or radartransmissions. Although some individual parts of the fuze are delicate, the overall fuze is designed towithstand some pretty rough treatment.Although both the M429 proximity fuze and the M423 PO fuzeare rugged and reliable, neither isperfect. In this imperfection therelies a major misunderstandingabout the proximity fuze as well asan unreasoning reluctance to usethem. When a regular PO fails, theprojectile is a dud. With a proximity fuze some of the failures areduds and some are earlies. Anearly is defined as a detonationprior to reaching the target. Withthe M429, the rate of earlies isactually less than 1 percent, whichis the lowest early rate of any comparable fuze. What is really hardto grasp is the earlies, althoughstartling, are not necessarily dangerous.Earlies are new and frighteningto most attack helicopter crews because they think that the round iscapable of exploding close enoughto be dangerous. Such not thecase. The safety mechanism of theM429 has been designed to insurethat the round must travel a safedistance from the aircraft before itcan physically detonate. As a matter of fact, the safe distance wasextended a considerable amount inthe M429 compared to theM423 PO fuze just to give an additional safety margin. Extensive testsby the Test and Evaluation Command have shown that M429 fuzedrockets are completely safe withrespect to the crew that i r ~ s them.

. Now let's discuss the troops onthe ground and the effect of anearly function along the flight pathof the round. We can break thisflight path into two parts. First isthe mid-range portion which isnormally a considerable distancefrom the ground, and second is theterminal phase as the projectile ap-26

The 2.75-inch folding fin rocketproaches the ground. Consider firstthe mid-range portion. A detonation here will normally cause nomore damage than any other object, such as falling brass frommachineguns, etc. The reason isthat these small fragments have avery high drag through the air andvery soon lose velocity to the pointwhere they become very small freefalling objects. In most cases, smallfree-falling objects do not have

enough momentum to penetrate thskin. At worst, a person might rceive a small scratch from one these particles. As an examplcontact one Of your friends whdoes bird hunting with a shotguand ask him what it is like to havshot raining down on him whesomeone is firing close by. Hwill probably answer irritating bmost certainly not harmful. Physcally speaking there is little chanBefore putting proximity fuze to use

I ,

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, ," , ,I; , ,r, ' ' ',. ;.;, /' ., '\ " ,

l' . f. ;4'I ,

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29/68

of harm; however, psychologicallyspeaking, there may be some con-cern until personnel understandthat these detonations are relativelyharmless.The last portion or the terminalphase of the flight path is a differ-ent matter. Here the round beginsto act as it was designed to act.However, you would normally as-sume that the terminal phase iswithin the general target area. f

, \

with the proximity fuzefiring in close support of groundtroops is necessary, then use of thenormal prescribed procedures offlying parallel to friendly troops,steeper angles of approach, etc.,should be considered. These nor-mal tactics are employed in closesupport, not so much because ofthe devastating effect of the war-head, but because of the inherentinaccuracies of the delivery system,mainly the rocket itself.

After

What is the safe distance then?Let me first remind you that thepublished minimum arming dis-tance for the M429 proximity fuzeis 500 feeP which was designed toprovide maximum safety to the fir-ing crew. A further study of thedata available indicates that theprobability of a casualty from an'"early" decreases rapidly as youincrease the distance from thepoint of burst. At a lateral distanceof several hundred feet from thepoint of burst, the probability ap-proaches zero. (For more detailssee reference in footnote 2.)Then why is a proximity fuzemore lethal if it doesn't significant-ly increase the distance or burstingradius of the round? Simply be-cause it lifts the burst up off theground and allows all those parti-cles that would have been buriedto act on the target area. As I saidbefore, this increase in lethality isin the neighborhood of three to 10times and in some cases even more.I think we would certainly call thata significant increase.In summary, it should be em-phasized that the M429 is a safe,rugged, reliable item which hasshown and will continue to show atremendous increase in effective-ness of the attack helicopter con-cept. Every man in the Army isvitally concerned with accomplish-ing the mission and increasingeffectiveness anywhere he can. TheM429 proximity fuze is a giantstep in the right direction. Othersteps are also being taken. One isa proximity fuze for the 40 mmgrenade used in the aircraft weap-ons system. t will be in production soon and in the bands of thetroops shortly t h e r e a ~ e r It is itemslike these that will end the days ofthe "charmed life Charlie" forever

1 1M 91340201, 2.75lnch Foldin, Fin A.rillRocket," 15 July 1968, p. 211.2 Joint Munitions Effectiveness Mlnu,1 Air To Surface), Slf. Distlnces for Friendly Troops"CONFIDENTIAL), TH61Al45, 18 Noy 68.

27


30/68

CI/flr/ie find Dflnny s IIIrite-inDear Danny: Something is mlssmg from tUH 1D/H dash 10 that a lot of us wrench twisteliked that is the instructions for computing the iformation that is entered on the GO-NO-GO takeodata placard. Huey maintenance personnel hereabouare having to refer to a November 1967 manual finstructions. Can we get that information back the manual?Danny's answer: The dash 10 was changed to githe pilot instructions on how to use the informatiyou and your wrench twisting buddies put on tGO-NO-GO placard. Instructions on how to compute the GO-NO-GO data is located in the Organzational Maintenance Manual (dash 20).Dear Charlie: Why is the red line at 3200 rpm the TH 13T engine tachometer? The way I read tdash 10, rpm is not limited to 3200. Which amto believe?Danny's answer: Charlie says I should do the woon this one so here goes. The red line is in the correplace on the tachometer and indicates maximucontinuous rpm (3200). For limited periods (notexceed 5 minutes), if you allow the rpm to go abo3200 the engine will not be damaged, provided 33rpm is not exceeded. From 3300 3400 rpm fany duration or 3200 - 3300 rpm for over minutes requires an entry in DA Form 2408-1From 3400 to 3500 rpm for any duration an inspetion is required. Above 3500 rpm the engine mube removed. In any case, engine operation abo3200 should be limited to the shortest time possibAny time 3300 rpm s exceeded the amount aduration must be recorded on DA Form 2408-1Dear Charlie: A lot of _us here at Ft. Leavenworare flying T-41s and have a hard time finding checlists. In fact, I've never seen a Department of tArmy checklist for the T -41. Is there such a pulication?Charlie's answer: Some aircraft such as the T-4and T 42 were procured as off-the-shelf' trainerManufacturers' handbooks are the only publicatioavailable and Department of the Army CLs are npublished for these aircraft. A request has beesubmitted for a change to this policy thereby allowing publication of dash lOs and dash CLs for aArmy aircraft.

U S ARMY AVIATION DIGES


31/68

And now here's the book towhom the news wouldn't bethe news without the newsHere's Dummy er. . . ah Danny

Dear Charlie: I feel that it is time to design anddistribute a dash 10 CL which can and will be usedby the individual aviators in the field. Right now weare required to use the dash CL as issued in (1)loose-leaf form, (2) stapled together or (3) stuffedin the TM 1500-1 binder which is too large, toocumbersome, too expensive, too hard to get andoften ignored in the form of a locally producedchecklist. Why shouldn't field units develop theirown CLs; USAA VNS has its own version. A firmstand behind a practical product has long been necessary in Army aviation.Charlie's answer: The checklists tbat you refer tohave been designed and are distributed as they become available. The TM 1500-1 has been proven tobe extremely effective as a container for the CL inall aircraft except the AH-1G, 0-1 and the OV-1and w are currently working on a modification ofthe binder for use in these aircraft. We had deviseda CL which can be used by any field unit, regardlessof its location, and which wlll provide standardization of procedures Army wide. USAAVNS does not,and I repeat does not, have its own version of theCLs. The school uses the approved DA checklists(except for off-the-sheH trainers) and has taken afirm stand behind these practical products. Why notjoin us in our stand?Dear Charlie: Investigation of a recent U-8D accident revealed that takeoff distance data was notavailable to the pilots for the most common takeoffOCTOBER 1969

condition of 20 degree flap. While it is realized thatproviding data for all takeoff conditions would notbe reasonable, data for a minimum run takeoff (i.e.,20 degree flap) would be more useful than the zerodegree flap data which is rarely used. Can this information be added to the dash CL and dash lOinthe next revisions?Charlie's answer: A performance data chart for the20 degree flap minimum run takeoff was not compned for the U-SD on initial procurement. Sinceyour request steps have been taken to obtain thisinformation for publication in the duh 10 and CL.Look for it in future changes to these publications The U-SD has been around for a long time and thisis the first request I have had for this data. Makesme wonder i f performance data charts are usedbefore takeoff or i f they are reserved for the accidentinvestigations.Dear Danny: We just got our new OH-58s and thenew manuals that go along with them. We've noticeda f w items in the operators manual that seem to bein error. The one that drew the most comments ison page 4-4, figure 4-2, normal approach and landing, power OFF. Step 6 says, 5 feet altitude, transition to forward flight. That maneuver would be abit difficult power off, wouldn't it?Danny's answer: Not just difficult - impossible.Thanks for looking at tbe manual so closely. Thatstep has been changed to read, Just prior to groundcontact, increase collective pitch as necessary tocushion landing. The new manual containing thischange is in distribution now.

,The response we have had from you\\workers in the field is appreciated. Anyquestions Charlie or I can help you withjust write and let us know Your letters donot have to be fancy, typed or any th ing-scribble me a not on an old C ration boxif th t is all you have I will guaranteeyou an answer


32/68

TORQUEThe Whyfors and HowforsWhat every good mechanic should know about a muchdiscussed but often misunderstood term torque

W HY IS torquing correctlyso important to property,life and limb? Torque this, torquethat, too much torque not enoughtorque what difference does it

make anyway as long as it's"plenty tight"? f you don't know,you're in trouble.Let's consider an imaginary ro-tor hub and main rotor blade con-nection and make some supposes.Let's suppose that: It's properly designed and willwork-also, that there's some wayyou can get into the contraptionwith a torque wrench. The nut and bolt are the cor-rect ones for this particular rotorsystem. The nut has been tighteneddown till the joint between therotor hub and main rotor bladefits snug. You didn't have a torquewrench and, in this case, notenough torque was applied.30

Lieutenant Colonel Charles W Sills

What will happen to this rotorsystem under operating conditionscan best be described by explainingSir Isaac Newton's third law whichstates, For every action there is anequal and opposite reaction." Thiscould best be likened to someone

punching you in the nose with hisfist-which, according to Newton'sLaw, is the same as you punchinghim in the fist with your nose withthe same force No matter howmuch it hurts-that's torque.Armed with this punchy explana-tion we can now make the followingobservations. f we start the bladerotating we know that centrifugalforce will try to throw it off and inthe direction of rotation-that'swhy we've got it bolted The out-ward force on the blade is 10,000pounds and, according to Isaac,there must be a force of 10,000

pounds in the opposite directionThe bolt has 10,000 pounds of puon it (if you suspended the rotohub from the ceiling and hun10,000 pounds on the rotor bladeyou would create the same situation) .You say you tightened the nudown "snug"? Well let's take

closer look at the rotor hub anmain rotor blade and you will sethat they have pulled apart sommeasurable amount. Know whhappened? The bolt actuallstretched-just like the 01 girdlEvery metal has a limit to which can be stretched and still return tits original size. This is called thU. S. ARMY AVIATION DIGEST


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elastic limit. Metal stretched -yond this limit is said to be n theplastic range and once the forcethat produced it is removed, themetal will never return to its original size (pr length) but will rema.in permanently changed-andweaker For example we w ll assUme that the Bolt stayed in theplastic range.Let's suppose (again) that wecan get our hands on a torquewrenchqn that main rotor bladecavity (while the blade is rotating ) and tighten down that nuttill we pull the hub and bladeback together so that they againtit snugly. Now, stop the rotorblade and let's see what's happened. First, we know the hubisn't trying to throw the rotorblades off because it's standing

OCTOBER 1969

still. The 10 OOO-pound force ofacceleration is gone but do youknow what we've got?-10,OOOpounds of torque on the bol t squeezing for it's worth. Youcan't see it, but that's torque. Andwhat's more, it's 1,000 poundsmore than we need in normal operating rpm so we have a little"gravy" in case of over-rev during af o ~ e d landing. Now are you beginning to see it? We've preloadedthe bolt to 10,000 pounds and anytime the rotor is turning at normaloperating rpm (or less) there'sreally no varying load on the bolt.Even if we exceed redline we'vestill got that safety factor (gravy)built in because the mechanictorqued the nut correctly.There's one more thing weshould discuss which will be easierto explain now that you understandtorque-it s just as bad to under

torque as overtorque because thisgives you a loose joint (so tospeak) and the rotor hub or nut orbolt or all three will fail from vibration and ultimate metal fatigueOne word of warning about another "trap" we don't want to beled into--using too small a nut onthe bolt. You can easily imagine how weak the connectionwould be if, for instance, we useda nut that was half a size or withhalf as many threads in there"holding on." It doesn't take anaeronautical engineer to figure thatone out.Finally, remember that how accurately that torgue wrench is usedcan mean the difference betweenlife or death-yours and possiblythe mechanic who torqued the nuttoo much, or not enough For along and prosperous life, let's allagree that there's only one correctsolution to torque JUST RIGHT.

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ARADMAC Sth Anniversary

Tl1e A ~ m y s I ~ l r g e s t d e p o t - I ~ v e l mQintenancefacility, ARAI)MAC, celebrates its eighth an-n iversary th ii year. From its Texas base at

C ~ r p u s 'Christi Naval Air Station, it repairsthe Army's mission-essential aeronauticalequipment

Colonel Luther G. Jones

THIS YEAR marks the eighthanniversary of the establishment of the U. S. Army Aeronautical Depot M a i n t e n a n c ~ Center (ARADMAC) within theconfines of the Corpus ChristiNaval Air Station, Corpus Christi,Tex. A,RADMAC operates underthe direction ' of the U. S. Army-{\viation Systems C o m m a n ~ , St.Louis, ' Mo., and perfprms depotievel maintimance on the Army'sinission essential aeronauticalequipment. This service also is provided t h ~ U. S. Navy, MarineCorps ~ d Air Force oli a limitedbasis. . .the seemingly improbaple situation of t4e Army qperating itslargest depot-level ~ a i n t e n a n c e f a ~cility in the h ~ a r t of a Naval installation dio not Gome abollt bychance, bUt as result of calculateddesign. freviQus articles concerning R D M ~ C appeared in the

DIGEST in November 1961; March1964; April 1965 ( Project Flattop ); and September 1968. Thisfacility originally was constructedin 1941 as a major ~ a v a l aircraftoverhaul and repair site. t f u ~ c tioned in that capacity fpr 18 yearsuntil deactivated by the Department of Defense in 1959. Subsequently, the Arm.y, recognizing theneed for an inhouse capability ofdepot-level maintenance n supportof its aircraft and assocjated equipment, petitioned the pepartment ofDefense for approval to developsuch a facility. Aftel' careful con

s i d e r ~ t i o n the present site wasselecteq. R e a c t i v a ~ i o n of the site

took place on 22 February 196when the Secretary of Defenssigned the activity into existenceIn addition to it primary main

tenance mission, ARADMAC haother a ~ s i g n e d responsibilitieThey inclpqe avionics maintenancand calibration, maintaining abilizationbase, providing a maintenance technical training base, peforming storage anq d i s t r i b ~ t ifunctions attendant to depot maintenapce activities a?d providin32 U. S. ARMY AVIATION DIGEST


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required worldwide mission supportto the Floating Army MaintenanceFacility.A by-product of the ARADMACoperation is that- it provides theArmy a means with which tocompare similar operations performed by industry for the Army.Acting as a ' "provipg ground,"

OCTOBER 1969

R D M ~ C checks the validity ofcertain specifications prescribed byindustry for Army hardware. tattests the reliability of establishedprocedures and the necessity ofcertain r e q u i r e m e ~ t s and items.This capability provides the Armywith first-hand knowledge enabIes t h ~ s s ~ m p t i o n of a s t r ~ m g ~ f

position in dealing with privateindustry.In the final analysis, however, overhaul production isARADMAC's main concern. Thisproduction is geared to deliver thehighest quality s ~ r v i c e a b k ~ aircraftassociated equipment to theuser in the required amount at theproper time. In other wrds, Wh nit comes to providing serviceableaircraft and engiQes, ARADMACinsures that our buyers "get the-Fefustest with the mostest " The im-

portance of this capability becamefully evident with the intensiflpation of hostilities in the Republicof Vietnam. That bbildup resultedin such greatly expanded Armyaviation overhaul requirementsthat the greater portion ofARADMAC;s accelerated effort isnow expended in suppOrt of requirements in Southeast Asia. tmight be said that duripg these trying times ARADMAC became ofage.Operations at ARADMAC began just six months after it openedits doors. The firs.t aircraft, ri 0 1( then designated L-19) liaison/observation type, and the first engine, an R-1820-103 type (used nthe CH-21B - Shawnee aircraft),rolled off the lines in September1961. Since, about -1,384 aircrafthave been p r o c e s s e d ~ 20,540 engines have been overhauled and astaggering 193,075 a i r c r a f ~ 'components have been worked. Anample of the increased tempo inproduction is the fact that 445aircraft were p r o c e s ~ e d in FY 68,exceeding t ~ e combined output ofthe first five years. Current prOOuc:-tion is increasing at an even f ~ t e rrate, as 25 3 s ~ r v i c e a b l e aircraftwere produced in the first half ofFY69.Engine overhaul has been evenmore d r a m a t i c - { v ~ r 20,000 'ineight years. these, more than11,000 were T-53 and T-55 typeturbine engines. The T-53 e n g i n ~is the mainstay of the Army'srotary wing aircraft and comprisesthe largest portion of the engineworkload at ARADMAC. t powers nine out of 10 helicopters inVietnam. History has shown thatArmy aviation ~ u p p o r t would havebeen seriously impaired pad notARADMAC responded to thepressing n ~ for serviceable T-53and T-55 engines. Over 6,600 wereturned Qut in FY 67 and 68. As itwas in the case of aircraft, thisprOduction was mo:re than the total

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output of turbine engines in thefirst five years of operation.The remarkable growth experienced by ARADMAC u ~ g itsrelatively brief existance also isreflected in the size of the facilityitself. Initially, 60 acres of landwith 22 buildings and 2,031,736of capital assets and productionequipment were transferred to theArmy from the Navy. The totalvalue was 9,111,185. At the endof the first year of operation,ARADMAC's work force totaled

34

1,249 civilians and 14 military.The latest figures, as of January1969, reveal the present extent ofthe expansion tp be: 119.4 acres of land containing 40 buildings, four miscellaneous structures, a 73,000 galloncapacity fuel tank farm and23,824,000 of capital assets andproduction equipment. Total value

over 58 million dollars. 1,559,558 square feet of maintenance, administrative, supply andmiscellaneous areas and troop

quarters; 762,922 square feet aredevoted to maintenance shop areasalone. A civilian work force of 4,564and 28 military. .The foregoing statistics represent a 641 percent Increase in thevalue of ARADMAC's capital assets and production equipment, a199 percent increase in land areaand a 363 percent employee increase. This growth was not merelythe response to an immediate needarising from the c o n f r o n t ~ o n inSoutheast Asia, but also the naturalevolution of a facility respondingto the ever ~ h n g i n g and increasingrequirements m he field of Armyaviation. From perhaps a limitedmuster of rather unsophisticatedfixed and rotary wing aircraft ofA bove left: a field of broken Hueys and. Cobras await repair in ARADMACworkshops Bottom left: aT 53 engine as-sembly line where final assembly prior totesting takes place Right: like new againthese helicopters will go back to Vietnamfor more c o m b ~ t

restricted capability, Army aviationhas burgeoned into a complex,highly sophisticated, expanding operation that demands corresponding changes in the capability of itsmaintenance facility.The keys to ARAOMAC's success can be found in three areas:employee attitude and technicalcompetence; the center's ability toadjust to new mission w o r k l o d ~and changing requirement; andthe way ARADMAC-is organized.During the difficult and somewhat hectic tooling-up period following the opening of the c ~ n t e rARADMAC was fortunate to havea ready source of skilled aircraftworkers, eager to pick up with theArmy where they left off with theNavy. This cadre of competentemployees greatly reduced the con-

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eightandalance Sense

No M TTER WH T some aviators seem to. think, the law of gravity has not been repealed.t is exactly the same today as it was when Oog theCaveman was keeping a sharp eye out for fallingcoconuts. Everything which goes up is due to comedown sooner or later, except maybe the price ofsirloin steaks.

nd flop down fairly hard at that, as a rule, unlessthere is a safeguard involved.Nope, the law of gravity hasn t been repealed oreven amended. The thing is that all of us, persistentcritters that we are, have been trying for the lastcouple of thousand years or so to do somethingabout the situation. Homemade wings flapped byone-man arm power. Gliders. Kites. Hot air balloons., t all seemed fairly hopeless until Wilbur andOrville came along and hooked a one-lunged engine

36

aior hester Goolrick

to their flimsy contraption down at Kitty Hawk.The age of flight had arrivedNobody needs to be told what happened after that.Before anybody could draw a deep breath, the RedBaron was operating over the skies of France, peoplewere flying the Atlantic in job lots and then aroundthe world, and your dear old Great-Aunt Ada, age90, was casually booking weekend trips from NewYork to Las Vegas to have a fling at the roulettewheels. They don t call Aunt Ada a charter memberof the jet set for nothing.You might say that if the law of gravity hasn tbeen amended, we have at least found ways to getaround it. Temporarily at least. Oog had troublelifting the big rock he put in front of his cave dooreach night to keep out the sabertooth tigers, but hemanaged to do it with the help of his friends. As

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for us, if there were any public outcry to turn Grant sTomb into a jetliner and the idea looked profitable,you could bet that before long somebody would comeup with a powerplant which could get it off theground.Under such circumstances, there is little wonderthat it is a temptation for an airman to lull himselfinto a feeling that gravity has been suspended forthe duration-that an aircrafts trusty engine will gethim into the air and keep him there no matter whatthe load is or how it is arranged.Else, how do you account for the number of accidents in Army aviation which have occurred becausethe rules regarding weight and balance-you mightcall them the antigravity shield-have been ignored?It just happens-all too often.t just might be worthwhile, as a quick brushup,to take a look at how the rules work and what hashappened when they have been violated.

WEIGHT LIFTEROne unchangeable fact is that a chap can t lift one

OCTOBER 1969

cr sh senseth e following 28 pages prepared by the U S rmyBoard fo r vtation ccident R esearch

ounce more than his muscles are built for withoutbusting a gusset. The law of inertia, blood brotherto the law of gravity, causes inanimate objects tohave a firm desire to stay glued to one spot, like aMissouri mule. The heavier they are the more oomphit takes to get them started-up or sideways. There salways a limit involved. Not even an Olympic weightlifter is going to try to heft an anvil in either handunless he wants t6 wind up with a set of musclesresembling guitar strings after a hard workout by arock and roll outfit .For an aircraft, vertical lift cannot exceed thepowerplant s ability to heave aloft a given numberof pounds under a particular set of conditions.Everybody knows this, natch. But here is onething that is frequently forgotten. ALL AIRCRAFT

C N BE D NGEROUSLY OVERLOADED.WHAT IS MORE, THEY OFTEN ARE.

It is common knowledge that any aircraft cantake more punishment than the handbook recommends if the occasion seems to demand it. Manu-

If it were profitable to turnGrant s tomb into a jetliner, someone would comeup with a power plantto get it off the ground

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WEIGHT ND B L NCE SENSE

A chap can t lift one ounce more thanhis muscles are built for without busting a gusset

facturers build in something extra, the way the soft-hearted sodajerker used to slip you an extra scoopon your ice cream cone when you stopped by onthe way home from school. That doesn t mean thatan aircraft, fixed or rotary wing, should be pushedpast the red line, except in the direst emergency.Sometimes, when the density altitude (DA) hassoared out of sight like an Apollo rocket boundnonstop for the moon, an aircraft can be pushed toofar. t will cling to the ground with a grip of steel.You just might be able to coax it into the air byusing spurs and horsewhips. You are not going tocoax it very high or very far.Just the same, the temptation is there for a pilotwho doesn t know or fully respect his dash 10. Thetemptation to forget the limitations. To overlookthem. Or, what is probably the case 99 times out ofa hundred, to gamble.

Gambling can be great sport, if you can afford tolose.As your Aunt Ada might observe when she jetsback from Vegas, some days you win and some daysyou can t make a nickel. The reason all horse playersdie broke is that when they were young, they werefalsely encouraged by the occasional long shot winnerLady Luck handed them on a platter.You might call it bait to catch suckers.38

YOUR MONEY DOWNThere are about as many ways to gamble at Vegasas there are to catch the common cold. The oddsalways favor the house.There are several interesting means by which youcan gamble with weight and balance with Army air-craft, particularly helicopters. You might well winfor a while, too, but don t worry. The odds catch upwith you in the end. You can grossly overload an aircraft under thesimple theory that it will obligingly haul upstairs any-thing you can cram into it. This is known in gamblingcircles as the Beginner s Approach and is not recom-mended by old hands. You can make a hasty estimate of the weightand balance situation rather than arrive at anexact figure. This is the mark of the born gambler.All orn gamblers are due to die broke. You can forget about the whole thing, ignorethe odds. People like this aren t even allowed at thetables at Vegas. They make the other playersnervous. You can look at one aspect of the situation andforget the other. In gambling circles this is referredto as Blind Man s Bluff and nobody will argue that it

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isn't as exciting as all get out. As long as it lasts,which probably won't be too long.One long-shot way of gambling is to tinker withdensity altitude.A LOT OF HOT AIRThe big trouble with density altitude is that youcan't see it the way you can a charging rhino or arunaway diesel tractor-trailer. When a pilot about totake off is confronted with a thunderhead whichlooks like the after-effects of a 20-megaton nuclearblast, he prudently stays on the ground. The sameairman, no matter how experienced, can be capableof sailing blithely off into the wild blue yonder on asunny day which is every bit as lethal for an aircraft

The heavier they are the moreoomph it takes to get them started

~ ~ ~ ~ . : ; ; ~ ; a s i . ~ ~OCTOBER 1969

All aircraft can be dangerouslyoverloaded. What is more,they ofte n ARE

which has. been loaded with no thought of DA.It's no great secret that hidden dangers are theones most likely to trip you. f Lucrezia Borgia'sdinner guests had been able to taste the deadly dosesshe slipped into their wine, her list of victims wouldhave been considerably shorter. f you could tasteDA, or feel it the way old soldiers predict weatherwhen the wound they got on D-Day begins acting up,there'd be no problem at all.DA may be hidden from you. t isn't hidden fromArmy rotary wing aircraft, which are as sensitive tosudden changes as a skittish colt. On a sunny Julyday, Ft. Rucker loo s the same at noon as it did atbreakfast. No new mOUli'tains, or anything. Just the

same old flat Alabama landscape we all know andlearn to love.But no Huey in its right mind is fooled. t knowsthat while Rucker's actual altitude is under 400 feet,its density altitude varies between minus 1,000 andplus 4,000, depending on the time of day and th-emood the sun is in. To a hard-working Huey thatmakes the difference extra pounds do to a horse ina handicap race. t will tell you so, too, anq in nouncertain fashion, if you lond' it with no thought toDA.Rucker is not an exception. There is hardly anyplace where Army aircraft are operating that DA

ranges can't vary widely gn a' day-to-day basis. Ajungle which can be comparatively cool at night canbe steamier than a Chinese laundry by midmorning.You can very nearly freeze to death on arid terrainduring the dark and a few hours later feel like thosethree lads in the Bible who ,were tossed into the fieryfurnace. t may be that under such conditions theweather might bug you to the pOInt where you couldforget about DA. Your faithfpI helicop

Army Aviation Digest - Oct 1969

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