Army Aviation Digest - Jul 1958

8/12/2019 Army Aviation Digest - Jul 1958

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EDITORIAL STAFFCapt Theodore E. WaskoLt John E. ArmstrongWilliam E. VanceFred M MontgomerySp 2 Jay Lewis Quinn

U. S ARMY AVIATION SCHOOLBrig Gen Bogardus S CairnsCommandantCol J.ohn J. Tolsonssistant Commandant

SCHOOL STAFFCol William H. ByrneFlight SurgeonCol William R. TuckDirector of InstructionCol Jay D. VanderpoolCombat Developm ent OfficeCol Edward N. DahlstromSecretaryLt Col James L. TownsendCO US VNS Regiment

DEPARTMENTSLt Col Raymond E. JohnsonRotary WingLt Col Thomas \V. AndersonTacticsLt Col Harry J. KernMaintenanceLt Col Howard I LukensFixed WingLt Col Thomas J. SabistonPublications andNon-Resident Instruction

The U. S. ARMY AVIATION DIGEST is an official publication of the Department of theArmy published monthly under the supervision of the Commandant, U S. Army AviationSchool.The mission of the U S. ARMY AVIATIONDIGEST is to provide information of an operational or functional nature concerning safety andaircraft accident prevention, training, maintenance. operations. research and development, aviation medicine, and other related data.Manuscripts. photographs. and other illustrations

pertaining to the above subjects of interest to personnel concerned with Army Aviation are invited.Direct communication is authorized to: Editor-inChief. U. S. ARMY AVIATION DIGEST, U. S.Army Aviation School Fort Rucker. Alabama.Unless otherwise indicated, material in the U S.ARMY AVIATION DIGEST may be reprinted provided credit is given to the U. S. ARMY AVIATION DIGEST and to the author.The printing of this publication has been ap proved by the Director of the Bureau of theBudget. 15 March 1956.Unless specified all photographs used are U. S.Army.

DISTRIBUTION:Active Army:OSD, JCS. OSA, CofS, DCSPER,ACSr. DCSOPS, DCSLOG. CINFO.CNGB, CUSARROTC. CRD. CMH,Technical Stf DA. MP Bd. USA ArtyBd, USA Armor Bd. USA Inf Bd, USAAir Def Bd, USA Abn Elct BdUSCONARC, US ARADCOM. OS MajComd. MDW, Armies, Corps, Div Brig,Sep Avn Co. Ft Camps CONUS),USMA. Svc Colleges. NWC, AFSC.ICAF, USA ARMS. USAAMS. USAES.USAIS, USARIS, USA Prim Hel Sch,Ord GM Sch. Ord Sch, USASCS.U S A T S C H T A G S U S A U S A C H SUSACMLCSCH, Fin Sch USAINTS.TJ AGSA, AMSS, Fld Comd AFSWP,Trans SuP Maint Comd MAAG. MilMis Mil Dist.NG: State AG.USAR: None.For explanation of abbreviations uaedsee AR 320-50.


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Boy coutsof America

THE EXPLORER MEDALION - This badge isworn by all Explorers. The medalion is acomposite of the Boy Scouts first classbadge the Air Explorers wings, and theSea Explorers anchor.

Brigadier General Ernest F. Easterbrook USDirector of Army Aviation ODCSOPS

F OR MANY YEARS the ArmedServices have been doing afine job in sponsorship of Boyand Girl Scout units. With fewexceptions, however, the Armyhas made no attempt to sponsorair or sea scouts. This was to beexpected since the Army did nothave the necessary aircraft andwater-borne equipment to support such units until recently.As a result only those youngmen living near Air Force orNavy installations had the opportunity to participate in theair and sea scout programs.With the present worldwidedistribution of Army Aviationunits, it appears that the Armyhas a fine opportunity to putnew life into its scout program.The majority of our military installations now have sufficientaircraft, allied equipment, andtraining aids to sponsor AirScout squadrons. There is not a.single Army Aviator who is not

qualified to teach at least oneaviation subject in furtheranceof this program.The Secretary of the Armyand the Army Chief of Staffhave published several lettersover the past five years encouraging Army personnel to take amore active part in scout activities. One such letter was DATAG letter, file AGAM-P (M),subject: Army Cooperationwith the Boy Scouts of America, dated 28 March 1955. Another was DA TAG letter, samefile number and subject, dated28 October 1956. As these letters point out, it will require nogreat diversion of effort to workwith these youth groups and itwould be of immeasurable benefit to the young men. Inclosure 2to the 28 October 1956 letteralso designates the Chief of Information, Department of theArmy, as responsible for staffsupervision of the Army's pro-


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Although not the final answer to this perplexing problemhere s another reminder about the difficulties of

Carburetor cingJohn S MaltroHi

SOMEHOW, YOU OZE for a mo-ment. And, somehow, you vefallen off on one wing at reduced power. N ow, suddenlytense, you straighten her up, adda little power and apply carburetor heat. t changes nothinga t all. Close to panic, you figureyou ve had it and begin searching for a place to set your planedown.Then you remember one last,dangerous remedy. You returncarburetor heat to full cold, pushup your power setting, and gradually lean out the mixture untilyou hear a sudden backfiring.Two or three times you let itfire this way; the engine sputters and now, miraculously, theprops pick up a few rpm and youquickly enrich the mixture andreduce throttle. Then you relax,cold and wet with sweat but relieved and thankful you escapedthis time. You fervently promise yourself you ll stay wideawake in the future to any condition that might lead to-CARBURETOR ICING.On a dry day you can dispense with this worry. OT whenthe temperature is below 15fahrenheit, the air won t holdenough water to cause y utrouble. Exception: you mayeven cause icing by applying carburetor heat in very low temperatures. In this case the carburetor is working well belowfreezing. f you pull on carburet-

Mr Maltrotti is a former taDmember of the U S. ARMY AVIATION DIGEST. The views expressedin this article are the author s and arenot necessarily those of the Department of the Army or of the U SArmy Aviation School.-The Editor

or heat, the temperature willrise in the carburetor to justabove freezing. Melting watercan then run to colder areas andfreeze. So, take care in applying heat in cold (0 to -10 fahrenheit) unless you are well acquainted with the way your particular engine operates.In the middle r ~ n g s through70, you must take special care.Icing is even possible at asteamy 90, and doubly possiblewhen the humidity is high orwhen it s rainy or overcast. Keepthat throttle in mind, too. Decrease its setting, as in a closedthrottle spin or long glide, andyour carburetor will make ice aseasily as an electric refrigerator-and a lot quicker.Remember that preheat is essentially an ice preventive. Icewon t form in a carburetor whenthe temperature of fuel and airis kept above the freezing point.One way to assure this is tokeep the intake air at least 80,measuring it with the carburetor air temperature gauge ifyour aircraft has one. Let it golower and you must keep youreye on the rpm or manifold pressure gauge. When power beginsto fall off, assume you have carburetor ice no matter what thegauges say-they may be off.In some aircraft, the Bird Dogfor example, you may not havea carburetor air temperature indicator. The answer is to flywith the carburetor heat fullon at critical temperatures eventhough it does not necessarilymean ice. Use of full heat usually increases fuel consumption.Naturally, you will take off


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full cold for full power. Onmost Army aircraft use of heaton the ground is not desirablebecause an alternate source ofair is used and is not filtered.But when idling or warming up,or after you have enough altitude, turn the carburetor heatback on. One final item, don'ttry to estimate the o r r e c tamount of heat if you have nocarburetor air temperature indicator; this may be dangerous.Rather, apply full carburetorheat. Any other position maynot raise the temperature to aneffective point.

DETE TING I EN ow how do you detect carburetor ice? What are the symptoms? Either too rich or too leana mixture will provide a drop inengine power with the formerusually accompanied by torching and the latter by backfiring.Or you may note a reduction inrpm, assuming your engine isequipped with a fixed-pitch prop.Or your manifold pressure maybegin to drop off, even thoughall other factors, such as throttlesettings, airplane attitude, andpressure altitude, remain thesame. Finally, engine roughnessor surging and, ultimately, engine stoppage should notify youof carburetor ice.Whenever ice accumulates, itwill seem as if an unseen handis very slowly c los i n g thethrottle. Your manifold pressurewill fall, although unevenly, because of ice deposits breakingaway now and then.Carburetor ice may form almost instantaneously, but undermost conditions it is a gradualprocess. If unwary, you maynote a drop in rpm and gradually

CARBURETOR ICING

open the throttle, unaware thatice is about to choke off theheartbeat of your engine. Forone icing test, apply full heatfor a few moments and returnto cold. If manifold pressure increases, you've had carburetorice.If ice forms near the jet orin the venturi, you may geteither enriching or leaning ofthe mixture, depending on thespecific shape or location. Forexample, if the fuel flow remains constant but the positionof the ice is such as to restrictthe venturi area, then the mixture might become too rich.And, incidentally, the carburetor would be further cooled because of the cooling effect of increased air velocity. In any case,whether the mixture is too richor too lean, the result is loss inpower.

WH T TO OOnce icing has begun, thenwhat? Leaning the fuel andbackfiring was mentioned as anultimate measure. If you haven'treached that emergency, applyheat to cause a further decreasein rpm and gradually increasepower. If rpm becomes criticalafter heat is applied, removecarburetor heat for a few seconds and let the rpm increase.Repeat this procedure until allthe ice is dissipated. Then ullheat. Doing it this way, insteadof applying full heat at once, willprevent ice from melting toorapidly and let the carburetorhandle any water or chunks ofice that result.But if you have no carburetorair temperature gauge, immediately apply heat-all the heatavailable - for if the engine


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fails the very source of yourcarburetor he a t disappears.Then move to the full cold position for a moment to determineif original power has returned.One final tip to remember: Although it is not too likely in today's aircraft, occasionally jigglethe carburetor heat control to

prevent the door from freezingin one position. To sum it up: Bealert for the conditions thatmake for carburetor ice or indications that it is forming. Knowthe idiosyncrasies of the airplane you are flying and memorize the proper technique for removing ice once formed.

YOU ARE ON A routine cross-country in a Beaver. Presentweather conditions are: thin scattered cirrus at 20 000 feet temperature 73 dewpoint 46 winds at 4 000 feet (your cruising altitude) 10 at 15 knots. The forecast for your destination, 250 nautical miles south, indicates that the weather there will be aboutthe same.After flying on course for 45 minutes you note your next reporting point is just 18 minutes away. You are enjoying the woodedscenery below when suddenly there is a large increase in manifoldpressure and a large decrease in rpm. Engine oil pressure indicateslow. You catch sight of a small field off your left wing and immediately diagnose the trouble as:1. Select the best answer or D Move propeller control HIGHanswers. PITCH throttle back ndo Carburetor ice. maintain sufficient airspeedo Cruising fuel mixture too to continue flight.lean. 3. Next you should:D Propeller failure. Nursing the engine proceedo Blown cylinder head. to the nearest suitable air-2. Your immediate corrective field and make an emergencyaction is to: landing.o Increase mixture control to Attempt a forced landing inFULL RICH and use hand the field you noticed.operated wobble pump to Adjust carburetor heat con-maintain fuel pressure until trol to keep carburetor tem-engine is operating properly. perature in the green ando Apply carburetor heat. continue the flight.o Move propeller control lever 0 Switch to the fullest tankLOW PITCH, ignition switch and proceed on your route.OFF, throttle CLOSED. References: TO 1L-20A-1.The correct solution to the PUZZLEH may be found on page 10.

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h e l i c o p e rc l e s e ro p e r a lo n sCaptain dwin o Carr rty

D8SERT EMPLOYMENT OF thehelicopter presents problemspeculiar only to sandy wasteareas. A thorough understand-ing of the difficulties involvedwill give the pilot and mechanicthe knowledge necessary to combat adverse effects of wind heatand dust. Remedies describedherein are mostly field expedients and should not be considered cure-aIls. They have beenfound effective under most conditions encountered in the desert.Problems found in desert operations can generally be dividedinto two categories maintenancedifficulties and flying hazards.Maintenance difficulties recaused by dust and heat andtheir effect on the machine. Ata hover for example the helicopter is virtually engulfed in acloud of dust. With each revolution of the blade fine sand acting as an abrasive is groundinto the hundreds of movingparts of the machine.This damage can be mini-

mized to a great extent byproper pilot technique and soundjudgment. For example takeoffsshould be made from the groundgoing directly into translationallift; whereas in landing pitchshould be reduced as soon aspossible after positive groundcontact is established. This cutsexposure time and also showsconsideration for people on theground.Although this technique helpsconsiderably it does not solvethe problem of excessive wearfrom dust and sand. Certain ad-ditional precautions should betaken by the mechanic and

Captain Edwin O Carr is FlightCommander, H-34 Flight, Departmentof Rotary Wing Training, UnitedStates Army Aviation School FortRucker, Ala. He was a battalion airofficer in Korea and previous to hispresent assignment was AviationOfficer at Camp Irwin, Calif. He isdual and instrument qualified and hasmore than 2900 /light hours. Viewsexpressed in this article are theauthor s and are not n e c ~ s s r i l y thoseof the Department of the Army or ofthe U. S. Army Aviation School.

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maintenance officer to furtherreduce abrasion.T IL ROTOR BR SION

The tail rotor is a primaryvictim of abrasive damage. Theleading edges of the tail rotorblades can literally be worna way. Covering the leadingedges of the blades with clothbacked tape will help to overcome this. Two pieces cut thesame length will assure properbalance.Tail rotor pitch-change linksmay be covered with a chamoisand secured with safety wire,with care so as not to impedethe travel or normal movementof these parts. This same principle must be applied to othermoving surfaces, especially exposed control linkages.

BL DE D M GEThe main rotor blades are primarily affected by heat. Closeinspections should be made frequently, for sun tends to drythe wood excessively, causingcracks and internal dry rot.Helicopters like the S i 0 u x

should be hangared when possible. If left standing in directsunlight, the metal leading edgeof the main rotor blade will expand. The wood portion will alsoexpand, but not as much as themetal. This expansion will causethe paint to stretch. Later whenthe metal and wood have cooledand contracted. the paint will remain stretched, leaving a beador bubble approximately oneeighth to one-fourth inch highon top of the blade where metaland wood join.In flight this has the same effect as ice on a wing and considerable blade efficiency is lost.8

This could mean the differencebetween being airborne or staying on the ground under conditions where operation is critical.This condition can be corrected. The entire rotor head isremoved, the bead sanded outand finished with fine sandpaper.Dope should then be applied tokeep moisture out of the wood.Finally, the rotor system is rebalanced and tracked. Consultapplicable T.O. for full procedure.) Extreme caution must beexercised not to oversand andunbalance the blades beyond tolerance limits. The best nd sim-plest solution is to keep the ir-craft in the sh de when it isn tbeing fl YWn.

OTHER PREC UTIONSProlonging the life of the engine under desert conditions canbe accomplished by keeping theengine clean. Daily gunking isnot impractical and will be wellworth the time and troubletaken.Plexiglass is extremely susceptible to heat and s n dBubbles should be cleaned often

and kept out of the sun as muchas practicable.Only high points of desertpreventative maintenance havebeen discussed. The best rule isto hangar the helicopter. Ingenuity and field expediency willgo a long way toward keeping anaircraft flyable.FLYING H Z RDS

Flying hazards are a pilotproblem. Thin air and extremeturbulence reduce both pilot andaircraft efficiency. Running outof power while hovering is themost frequent problem an aviator will face and is not to be


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confused wi t h settling-withpower. Settling-with-power issettling into your own downwash and is the result of poortechnique. Running out of powercan usually be attributed to thinair, i.e., high density altitude.This condition can be describedas attempting to hover with insufficient power to maintainrotor rpm.Assume that upon completionof an approach, a hover isreached. Pitch is increased causing the rpm to fall off so thatthrottle must be added. Thenthe process repeats itself.In running out of power thiscycle progresses to the extreme.Power is not available to turnthe blades at the necessary rpmto maintain hovering altitude.

Eventually, since rotor rpm isthe primary concern in a helicopter, it is necessary to reducepitch, and landing is made. Theeffect is very similar to a tallgrass operation. The safest wayis to hover only over areaswhere a safe landing can be effected. However, this is not always possible.There s a solution to thiscondition. Most helicopters havean allowable overrev which, inthis case, must be used. Whenhovering over terrain where alanding cannot be made, this extra rpm will give the pilot asecond chance. If the additionalrpm cannot be held at a hover,the best solution is an immedi

ate takeoff. To avoid settling,it may be necessary to use upmore of the flyable rpm. Mosthelicopters have a minimum allowable tolerance and 0 n c etranslational lift is attained thelost rpm can be regained withlittle difficulty.

HELICOPTER DESERT OPERATIONS

Flares should be avoided. Usually the helicopter will f athrough and ground contact willbe hard, causing damage to theaircraft.

PRIM RY H Z RDSevere updrafts and thermalspresent another problem - extreme turbulence. This can beovercome through smooth control technique. Although th

helicopter is essentially unstable, it does have limited inherent stability. For lack of abetter word, call this characteristic pendulous stability. Therotor disk is always coned whenthe collective pitch is applied.The bulk of the machine hangsfrom the vortex of this cone.The effect is similar to thedihedral of the wings on fixedwing aircraft and the helicopterwill tend to right itself to someextent. This is mentioned because turbulence is not the maindanger.The effect of turbulence onthe pilot is the primary hazard.But pilot fatigue can be greatlyreduced with common s n s emeasures. Cyclic friction shouldbe tightened. The aviator shouldrest his cyclic arm on his legwhenever possible, thereby reducing control movements.The aircraft should be allowedto right itself, if it will, beforea correction is applied; then thecorrection should be as small aspossible. Strain on man and machine is thus reduced and thecontrol touch of the pilot becomes smoother.Airspeed should be reducedwhen flying in gusty, turbulentwinds. This increases the margin of safety against retreatingblade stall and reduces overall

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strain on the helicopter.What you don't see may hurtyou at times Dust devils or"twisters" are common to desertcountry. You can spot them inthe distance as they spiral upward with a characteristic column of sand, dust, and debris.The b i r d s nonchalantly ridethese currents of air to greatheights-but that's strictly forthe birds. When you see these"twisters," give them a wideberth.

HOVERING H Z RDFor safety's sake, all takeoffsand landings should be made directly to and from the ground.This is especially true of opensandy areas. At a hover, zerovisibility is not uncommon. If

normal takeoff from a hover isattempted, it is similar to aninstrument takeoff. Visibility in

a dust cloud is the same as flying in fog. Vertigo is not improbable. Since helicopters ofthe Sioux v a r i e t y r e notequipped with instruments, aserious accident c n result.Again, common sense measureswill prevent much trouble.On the personal comfort side,veteran desert aviators recommend carrying water on allflights in event of a forced landing in remote areas. Lip chapsticks, zinc ointment, a cap withsun visor, and dark glasses areconsidered necessities.Desert helicopter flying hasits better side. t can be pleasurable and safe. On clear days,visibility is phenomenal and inearly morning the air is unbelievably smooth. However,pilot and mechanic must beaware of desert difficulties andremember their own limitations.

~ t PUZZL ROn the basis of the factual information contained in the PUZZLER on page 6 the recommended solution is as follows:Question Number One:Propeller failure. (A sudden increase in manifold pressure anda large decrease in rpm are the general indications of this.)Question Number Two:Move pro.peller co.ntro.I to. HIGH PITCH, throttle back and maintain sufficient airspeed to. continue flight. (These actions should betaken immediately to avoid damage to. the engine and a total loss

of power.)Question Number Three:Nursing the engine, proceed to. the nearest suitable airfield andmake an emergency landing. (Even with low oil pressure, it ispossible to maintain minimum rpm and make an emergency landingwith limited Po.wer. (One caution: NO GO-AROUNDS )You are en uraged to su bmit commen ts on the n ten ts of the problemto the U. S. ARMY AVIATION DIGEST The Editor

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T I S YEAR THE Civil Aero-nautics Administration celebrates its 20th anniversary. Itsgrowth reflects the rapid expansion of aviation, both civilianand military, in the UnitedStates. Most Army Aviators arefamiliar with the operation ofthis organization and its subsidiary offices; they daily comein contact with the CAA throughone means or another. But veryfew Army Aviators are familiarwith the history of this complex regulatory agency, whichhas amazingly paralleled the advancing design and technologyof aircraft.

f your airplane flies on thecivil airways of this country,you ll come in direct contactwith the CAA. You are giventraffic clearances by CAA employees and directional guidanceby CAA radio facilities. Whenyou land at a civilian field,chances are that the airport wasbuilt or improved with CAA aid.Roughly half of CAA s 23,600employees are engaged in maintaining and operating the federal airways. This network ofair highways totals abo u t106,000 miles.A brief history will help youunderstand CAA. The first navigational aids to pilots were designed and operated by theLighthouse Service, an agencyunder the supervision of the Department of Commerce. Callingon their previous experiencewith ships that ply the ocean,the men of this service naturallyfavored lights for night flying.

At the time, aeronautical adaptations of the radio were justbeginning to show promise.In 1926, the AeronauticsBranch of the Department ofCommerce was created by Congress, and men with extensiveaviation experience were employed.In 1928 the four-course, lowfrequency, radio range was accepted as part of the airwayssystem. Since then, there hasbeen continuous improvement;and now these range stationsare being replaced by VOR.

The CAA has been successfully controlling air traffic since1936. Ten controllers comprisedthe original group. Now 10,000persons are employed to performair traffic control duties at 530communications stations and 26centers. These Air Route Traffi Control Centers (ARTCC)control all en route traffic operating under IF R conditions,delegating to airport controltowers the control over trafficoperating in a radius of a pproximately 20 miles around anairport. The Air Traffic Communications Station (ATCS),which links you to the controllers, forms a vital segment ofthe control system. These threefacilities, the centers, towersand stations-linked by 130,933miles of teletype and 135,764miles of interphone lines-work

Continued on page 16)The views ex pressed in this articleare not necesswrily those of the De-p tment of the Army or of the U. S.Army Aviation School.-The Editor

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M STERRMY

VI TOR

Colonel Jack L. Marinelli, the Master Army Aviator above, ispresently assigned as the Chief, Special Projects Branch DCSLOG,DA, and is charged with the logistics monitorship of Army Aviation, Guided Missiles and Atomic Weapons. Upon entering the Armyin 1940, he attended the Cavalry School, both horse and mechanized.After graduation he was assigned to the 113th Cavalry, and laterjoined the 4th Division as Aide-de-Camp to the Commanding General. After completion of the Field Artillery Pilots Course No. 12,he went to Europe as the Aviation Officer of the 71st Field Artil-lery Battalion II Corps, and 5th Army. He was one of the firstArmy Liaison Pilots to be awarded the DFC.Upon Colonel Marinelli s return to the U. S., he became the firstDirector of Army Aircraft Tests at AGF Board No.1 now knownas the Army Aviation Board. During the ensuing period he at-tended the Advanced Artillery Officers Course, and became theAviation Officer for the Office, Chief of Army Field Forces, DA;Headquarters Far East Command; and Headquarters Army ForcesFar East.Colonel Marinelli has held an instrument rating since 1951 andis currently rated in all Army rotary and fixed wing aircraft. Inhis 16 years with Army Aviation, he has accumulated over 3,800hours of flight time.2


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LARGE I R C R ~ T and busy rl n-ways requIre an ever-Increasing alertness on the part ofall pilots. One of the more dan-gerous hazards this combinationcan produce is the lingering effect of wingtip vortices. Invisible, vicious and tenacious, theseswirling masses of turbulent aircan throw an aircraft out ofcontrol in a matter of seconds.When atmospheric conditionspermit vortices to remain overthe runway, even the cautiouspilot may be taken by surprise.The following excerpt was takenfrom the report of a Bird Dogaccident that happened recently:

The pilot was taking off fora service flight to one of theunit's field parties. Just prior tohis taking the runway, an AirForce C 119 had taken off. TheC 119 was estimated at 500 feetaltitude and had turned crosswind, which is normally considered a safe distance and altitude to allow wingtip vorticesto dissipate. The pilot was cautious while taxiing and felt noeffect of vortices. After receiving takeoff clearance, he checkedthe runway and added powerfor a normal takeoff. Just afterbecoming airborne, he experienced difficulty in maintaining

ingtip vortex caused this accident

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B i r ~ mo Q lu 65tr IFORSOOTH, SAYETH THEKNIGHT, and rose from the

round table. Mine IN baskethath emptied into the properchannels. Now is the time tomount the iron bird and soarforth. The month end approacheth and I am short the fourthhour."So saying, the warrior arosefrom his desk, zipped into hisnylon rm 0 r

and left thatplace of cubi-cles. He traveleth to the placeof the roaringbirds, signeththe necessaryforms and strappeth on a greatbrown canvas bag. Stridingaround the winged monster, hepulleth here and poketh therein a manner to checketh thefirmness of the fowl's feathers.Seemingly pleased with the

condition of the beast, t h eknight mounted and did variousthings to the bird's interiorwhich caused it to roar andshake. t waddled off to a stretchof black earth, took a runningleap and soared upward with arush of wind.And there cometh a feelingof great joy to the knight. Hezoometh around the sky withabandon until an hour had goneand it were time to returneththe bird. The warrior descendedfrom high places and flew beside the black earth, causing thebird to cease its roar. He turneth it toward the lighting pathand pulled down some feathersalong the back of each wing. Asthe bird approached the ground,it was seen that one wing flewlower than its mate. Some saidthis was because the wind blewacross the black earth.The bird alit on one foot,

takeoff attitude. The B i r dDog's left wing came up sharply,causing the aircraft to move tothe right. The pilot's corrections had no effect and the leftwing continued to rise until theright wing struck the ground.The pilot then recovered controlof the aircraft and a safe landing was made without furtherdamage.

PROJECT CONCLUSIONSFrom a project to determine

the effect of wingtip vortices onArmy aircraft, the U n i t e dStates Army Aviation Boardproduced these conclusions:a. In regard to duration, char-

acteristics, and intensity ofwingtip vortices:(1) The duration is governedprimarily by the atmosphericconditions existing. Any air disturbance has an immediate dispersing effect.(2) The greatest disturbancesproduced by any aircraft occurwhen that aircraft is travelingat low airspeeds, such as inlanding and takeoff patterns.(3) No quantitative conclusions could be reached on intensity; however, the vortex effectcan be of such intensity that aserious control problem will becreated when light airplanes encounter the disturbance at low

*It appears that this should have been received as the signal to set the BirdDog back on the runway. See "Careful Tip Tornado Ahead," December 1957DIGEST.-The Editor4


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whereupon it launched itselfinto the air again, turned itsnose into the wind, and lit hardto the extent that its l g sspreadeth on the hard ground.Its whirling nose bit angrilyinto the black earth and thebeast cast one wing down andslid along on its belly. The ironmonster came to a grinding haltand a great quiet descendedupon that place. The knight dismounted and woefully regardedthe crumpled bird.And there came a troop ofrolling cavalry calling themselvesinvestigators, and they t oo kmeasurements and did all manner of things to the broken bird.And all who witnessed the falling of the bird were called andspake long to them and theywriteth in the book.Then, he of the gray beardspaketh to the knight in thismanner:airspeeds.b. Wingtip vortices can produce momentary loss of controlof Army aircraft and could, under certain circumstances, produce structural damage to lightaircraft.What causes this hazard?Basically it is (a) the wingtipvortices and (b) the swirlingpropeller or jet wash of largeaircraft that create a turbulence which can upset anotheraircraft.

What types of aircraft doesthis affect? The answer is: alltypes and all makes of aircraftfrom light two-seaters to heavyfour-engine transports h a v ebeen seriously affected by thisturbulence.What types of aircraft are re-

Verily, verily, I say untothee, thou hast lost all directional control and it were betterthat thou hadst taken this birdagain around It is written thathe who bounceth shall encounterthe crooked path. 'Tis far betterto push the throttle than bootthe rudder, for the spur isquicker than the rein.However, the records of thyform indicate thou hast onlyseven and a half hours of birdtime in the last half-year. Forthis, thy supervisor shall becalled to task.Go, and when thou comestagain to the bird, bring the senior knight that he may instructthee how to alight thy bird withsafety."ported to have caused this turbulence? Pilots have reportedsevere or dangerous turbulencecaused by various types of aircraft during their landing ortakeoff operation, but the mostfrequent and severe exampleswere reported behind the largestcommercial airliners, such asDC-6s, Constellations, DC-4s andDC-3s.Recommendations:Allow plenty of space betweenaircraft in the traffic pattern.f there is any doubt, delay

The Gray Hair Department is prepared by the U. S. Army Board forA viation Accident Research staff withinformation from its files. Views ex-pressed in this department are notnecessarily those of the Departmentof the Army or of the U. S. ArmyAviation School. The Editor5


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your takeoff or your landing approach.Make approaches and landings on the upwind side of therunway.When entering an area justvacated by another aircraft,maintain adequate flying speedwell above your aircraft's stalling speed.Be alert and prepared for turbulence during landings, approaches and takeoffs.

CAA nniversary continued f rom p geclosely with each other to maintain a safe and orderly flow oftraffic.Wherever you may fly, theCAA is there with an interestin your safety. Watching over

TO: EditorThe reason for this note concernsyour March, 1958, issue of the DI

GEST. On page 32 under the headingGrade Structure, C2, SR 210-20-15

is listed as the regulation concerningestablishing a revised grade struc

ture for aviators. I have checked theIndex of Administrative Publications,dated January 1958, with changes,and cannot find this regulation listed.I did note that the 210 series appliesto installations and not to gradestructures. My question i s -what isthe correct number if by chance thisone isn't correct?

My interest lies in the fact that Ihave National Guard pilots who havebeen in battalions as lieutenants for16

you is a dedicated team, bringing you every available aid theycan which has been developedand perfected in the 20-year history of this increasingly important agency.

over ten years. Maybe this is thebreak they've been looking for all ofthese years.

Any assistance you could give mewill certainly be appreciated.HENRY R. MANGUM, JR.Captain ArtyArmy Aviation AdvisorWest Virginia NG

Ca reful study of the AR and SRindex reveals no such SR. Apparentlya typing error somewhere along theline went unnoticed and the referenceshould be C2, SR 310-30-15, dated 16July 1957, entitled Organization andEquipment Tables Personnel. f thisdoesn't fit the bill, let us know andwe ll pursue i t further.-The Editor


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The new operations building for Lowe AAF (top) is located atthe south end of the tie-down area and commands a clear viewof the double traffic pattern in use at the field. A snack bar ishoused on the first floor. Two new hangars one of which s undercOl1. truction in the bottom photo), plus a third already in use,will greatly assist maintenance personnel to keep the propernumber of aircraft available for training.

Date post:	03-Jun-2018
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Army Aviation Digest - Jul 1958

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