Army Aviation Digest - Sep 1961

8/12/2019 Army Aviation Digest - Sep 1961

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SEPTEMBER 96

ARY USAARUT RUCI ER, ALA


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VI TION JGESTEDITORIAL STAFF

SEPTEMBER 1961

U. S. ARMY AVIATION SCHOOLMaj Gen Ernest F. EasterbrookCommandantCol Warren R. Williams, Jr.ssistant CommandantCol Allen M. Burdett, Jr.

Deputy sst CommandantCAPT JOSEPH H POOLEFRED M MONTGOMERYRICHARD K TIERNEY

DIANA G WILLIAMSSGT THOMAS M LANGLINDA K FOLSOM

VOLUME 7 SCHOOL STAFFNUMBER 9

ARTICLESHOME ON ONE, Capt Thomas N Hurst, ArtyTHE IMPORTANCE OF PLANNING, Robert M. DickinsonWHY NOT TIGERS? Gerald T. Thorpe .MAINTENANCE PERSONNEL TRAINING PROGRAM,Lt Theodore S. Chase, TC .SAFETY IN ACTION, William E. Carter .AUTOROTATIONAL CHARACTERISTICS AND RECOVERYALTITUDE REQUIREMENTS FOR THE HU-IA HELICOPTER,Bayard T. McWilliamsTWXARMY COMMAND CONTROLLED AERIAL SURVEILLANCEVEHICLES, Capt Edward C. Kopeschka, ArtyNEW ACCIDENT REPORTING FORMSAVED BY GROUND EFFECT .NEW THREAT TO FLIGHT SAFETYFALCON'S NESTCRASH SENSE

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MEMO FROM FLIGHT SURGEON, Col Spurgeon Neel, MC Inside Back

eep Those anuscripts omingBelp the Army Aviation Program by eontributing usefulinformation on subjects listed on the masthead right) ofthe DIGEST Everyone is urged to beeome a joiner - join

the eontributors. If you have a suggestion for improvement*if you disagree with a certain article, or if you have a storywith a safety message, please put your thoughts on paperand mail them to the editor. If your .rticle is publishedy o u ~ be eligible for a 50, 75 or 125 CASH award. And

w o l d n ~ t i t make you feel good if your safety message orstory helped to save another Army Ayiator's life? Howabout making your contribution todayKeep Tltose Manuscripts Coming.

Lt Col James B. Gregorie, Jr.cting Director ofInstructionLt Col C. E. LawrenceCO US VNS RegimentLt Col Morris G. RawlingsCombat Developments OfficeLt Col Julius E. Clark, Jr.Secretary

DEPARTMENTSLt Col Raymond P. Campbell, Jr.TacticsLt Col Conway L. EllersAElvanced Fixed WingLt Col Wayne N. PhillipsRotary WingLt Col Harry J. KernMaintenanceLt Col John R. RiddlePublications andNon-Resident InstructionMaj Roy V. Hunter

Primary Fixed Wing

The U. S. ARMY AVIATION DIGEST isan official publication of the Department ofthe Army pUblished monthly under thesupervision of the Commandant, U. S. ArmyAviation School.The mission of the U. S. ARMY AVIATION DIGEST is to provide information ofan operational or functional nature concerning safety and aircraft accident prevention,training, maintenance, operations, researchand development, aviation medicine andother related data.Manuscripts, photographs, and other illustrations pertaining to the above subjects ofinterest to personnel concerned with ArmyAviation are invited. Direct communicationis authorized to: EditorinChief U. S.AR.MY AVIATION DIGEST, U. S. ArmyAviation School, Fort Rucker, Alabama.Unless otherwise indicated, material inthe U. S. ARMY AVIATION DIGEST maybe reprinted provided credit is given to theU. S. ARMY AVIATION DIGEST and tothe author.The printing of this publication has beenapproved by the Director of the Bureau ofthe Rudget, 22 December 1958.Views expressed in this magazine are notnecessarily those of the Department of theArmy or of the U. S. Army Aviation School.Unless specified otherwise, all photographsare U. S. Army.Distribution:To be distributed in accordance withrequirements stated in DA Form 12.


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HEN THE FIRST Cariboucame to the Army A viation School several months agothe Director of the Departmentof Advanced Fixed Wing Train-ing directed that an attempt bemade to establish a standard-ized single engine procedurewhich could be applied to allArmy multiengine airplanes.A t first this seemed t be animpossible task. At that timeseveral different procedureswere in use depending uponwhat year you went throughschool - all this on one air-plane. Second several twinengine aircraft were in use although not all were issued tofield units.

Captain Thomas N Hurst

After a closer look it appeared that if the major stepsin the procedure were generalized enough a single procedurecould be established. It washoped that if this could bedone it would be acceptedworldwide. Everyone who wentthrough AAF pilot trainingduring World War II remem-bers the old GUMP check. Ifyou found yourself in a strangeaircraft or if procedures wereforgotten you could always fallback on this and it seems never go wrong. If the Army coulddevelop one single-engine procedure which would be as universally accepted as GUMPthis would be a major accom-

plishment. As a result of thisstudy the following procedurewas adopted:

1 DETERMINE whichengine has failed.2. FEATHER the deadengine.3. METO power on the goodengine. . n4. ELIMINATE externaldrag.

Capt Hurst is chief of the Multi .engine and E xaminers Branch.Instrument Division Dept of AdvF / W Training USAAVNS H eis a Master Army Aviator withapproximately 6 000 hours in bothfixed and rotary wing aircraft.

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SEPTEMBER 19615. CLEAN UP the cockpit.N W let us examine each f

these steps in detail.DETERMINE

AlthDugh this is n t actuallya part of the single-engine procedure, it must be included inthis discussiDn because the single-engine prDcedure cannDt becDmmenced until after this isaccDmplished. This discussiDnis not cDncerned with such errDrs as fuel starvatiDn due tofailure to switch fuel tanks,failure to apply carburetorheat, Dr Dther acts of omission

n the part f the pilot. Neitheris it cDncerned with a missingengine or. partial pDwer loss. tIS cDncerned with what to doif YDU IDse an engine. Any single-engine procedure is predicated upDn the assumptiDn ofsudden and cDmplete pDwerIDSS f the critical engine. Dueto the direction of rDtatio.n,this is always the left engineon United States aircraft.There are several ways to determine which engine has failed. On some aircraft, such asthe L-23, the dead foot - deadengine method is the mDst reliable, since the engine instru-ments will nDt tell you whichengine is DUt. Manifold pres-sures will be approximatelythe same, and the prDpeller onthe, dead engine will windmilljust abDut as fast as the otherone.Some pilots prefer to retardthe dead throttle as thee nextstep in procedure, Dr as a meth-od of identifying. Bear in mindthat this serves only to confirmwhat you already know. t ensures against feathering thewro.ng engine. This step is usedextensively in student trainingas an added safety precautiDn.Actually, if the dead enginehas been positively identified,2

as it should have been by differential rudder pressure, thisis an unnecessary, time consuming step, and can be omitted. In other words, if youknow you are right, gO aheadand feather.Some aircraft are equippedwith torque meters, which givethe best indication of whichengine is out. The CaribDu isequipped with thrust meters.The indicato.rs are graduatedin inches of water, and a zero(or below thrust indicationimmediately identifies whichengine has failed. Incidentally,the Caribou also. has an automatic feathering system inconjunction with the thrustmeters. A thrust differentialof 4 inches of water duringtakeoff wil l automaticallyfeather the low-pDwered engine.FE THER

This is by far the most important step in the entire procedure. Your aircraft may beable to stay airborne dragginggear or flaps, but not with awindmilling propeller. hemost serious loss is not justfrom the drag created but fromthe lo.ss of directional controlresulting from assymetricalpower. A sudden yaw results.,and the airplane may go intoa violent roll if something isn'tdone in a hurry. Rudder is applied, resulting in further dragand an accompanying loss inairspeed. Feathering the propeller eliminates virtually allthe drag from the windmillingpropeller, and adequate ruddercontrol returns. This stepalone may be sufficient to allow the pilot to regain directional contro.l f the aircraftand get back on the gro.undsafely, even if the other stepsare not carried out.In the case of internal failure

or pro.peller imbalance, seriousvibrations are set up and mayshake the airplane to pieces ifnDt eliminated. The importantthing to remember is to featherimmediately once the dead engine is positively identified.While determining is a pre-liminary procedure, featheringis the first step of executiDn.METO POWER

METO means maximum except for take o.ff. Some manu-facturers and other servicesmay refer to this as maximumcDntinuous power Dr normalrated power. In an effort toward clarity and understandingas well as standardizatio.n, theArmy has now adopted theterm METO. This is not take-off power. t is usually the nextlower setting and has no timelimit as far as the engine isconcerned. This setting re-quires a rich mixture, and theFULL RICH Dr AUTO RICHposition on the mixture control lever ShDUld be selected before advancing the propellerlevers and throttle.The amount of power necessary varies with type of air-craft, circumstances, g r 0 s sweight, and Dther co.nditiDns.Rather than consider all thevariables and try to. determinehow much power is required tomaintain a desired airspeed, always apply METO power first.f it is later determined thatthis much is not required, it

may bereduced.ELIMIN TE EXTERN L DR G

This means simply gear andflaps UP. Since the landinggear contributes only drag, itShDUld be retracted first. Theflaps contribute lift and drag,and while retraction may be delayed or the flaps left down,there will be some sacrifice inairspeed and control responses.


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This is especially true in flaperon aircraft such as the Caribou, or in aileron droop air-craft. If in a copilot airplaneretract gear and flaps simultaneously.CLE N UP

Turn off items that are notneeded. The emergency has already been solved with thecompletion of the previoussteps. This step includes re-tarding the dead throttle andpropeller levers, moving mixture control lever to IDLECUT-OFF, shutting off magne-tos, generator, fuel boosterpump, etc., as may apply to aparticular aircraft. There is noneed to hurry during this step.Probably no damage would re-sult if it were forgotten. It isa matter of good cockpit procedure to have everythingturned off that isn t being used,and this may be done whentime permits.R ISE TH E DE D

While not listed as a separatestep, the wing on the deadengine side should be raised to50. This will eliminate some ofthe rudder pressure and provide better directional control.With a high rudder such as theCaribou has, which is above theturbulent area behind the engines and wing, almost no rud-der pressure is required to holdheading. This is due to theaerodynamic qualities of thetailplane and the turning moment of the vertical fin. Thistype aircraft has very goodsingle-engine characteristics.

IRSPEEDEvery item in the emergency portion of this procedureis aimed at maintaining desiredairspeed. At very low air-speeds, the aircraft may be-

come uncontrollable and spinin. In this case, power must bereduced. From a psychologicalpoint of view, it is very difficultto reduce power when airspeedis low, especially if you are justabove treetop level. For example, in the L-23D, if an engineis lost immediately after take-off at 80 knots lAS with takeoffpower on the good engine, theairplane will be uncontrollable;however, it is possible to main-tain level flight and controllability at 73 knots lAS 69 insome cases) if power is reducedaccordingly. Pick the lowestpoint in the terrain, if necessary, and lower the nose to pickup airspeed. (For those- whohave not had the scenic, lowlevel tour of the Choctawhat-chee Valley near Fort Rucker,it is very interesting in the fallof the year when viewed fromthis altitude.) With airspeed,we can gain altitude, havedirectional control, and returnsafely to the field.

SUMM RYAny single-engine procedurecan be varied to meet particu-lar circumstances. For example, if safe single-engine speedis attained before lift-off andthe landing gear is retracted assoon as definitely airborne,there is only one thing to d(}-

feather. (This is done automatically on some airplanes.)For all other regimes of flightbefore entering the trafficpattern, feather and increasepower; gear and flaps will already be up. After the landingcheck is completed, a new phaseis entered; gear and flaps mustbe retracted in proper sequence. On final approach aftera landing is assured, merelycontinue approach at reducedpower and make a normal landing.

HOME ON ONESince in emergencies pilots

always revert to the methodthey have been practicing intraining, any standardized single-engine procedure must beapplicable at any time duringthe flight. However, ratherthan remember a procedureand be able to execute itaccurately, it is far better toavoid all critical areas of flightif the mission permits. In thiscase, loss of an engine will notbecome an emergency. Andremember, that second engineis for making the forced landing, not for continuing to destination.

ENGINE FIRE IN FLIGHTThis subject probably de

serves separate treatment dueto its importance; however, itis included here because it doesinvolve single - engine flight,and no single-engine discussionwould be complete without atleast mentioning this aspect.The same standardization instructions can be applied tothese procedures as well as single-engine procedures. Sincethe Caribou is the first Armyaircraft to have engine fire extinguishers, this seems t be agood place to start.After much experimentationand discussion, it was finallydecided to reduce the procedurefor engine fire in flight to thefollowing three major steps:

1 FEATHER,2 FLUIDS, and3. EXTINGUISHER.

FE THEROther services and agencieswere consulted in an effort togain knowledge from thosehaving more experience thanthe Army in this field. Theywere emphatic in defendingthis as the first step. The- obj ect of feathering is to stop


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SEPTEMBER 1961the flow of combustibles intothe engine oompartment, thetheory being that if there isnothing to burn, the fire will goout. It is claimed that stoppingthe rotation of the engine willdo this quicker than anythingelse.FLUIDS

The next step is to cut off allfluids flowing into the engine.Move the mixture lever to theIDLE CUT-OFF position; thenturn off the fuel and oil (theCaribou is e qu i p p e d withguarded toggle s wi t c he slocated on the emergency panelfor this purpose). Closing theseswitches cuts off these combustibles at the main firewall.Other aircraft have separateshut-off valves, although theymay not be as conveniently located as in the Caribou. Futureaircraft will have only one control to perform all of thesefunctions. One movement onthe part of the pilot preparesthe engine for the extinguishing agent.EXTINGUISHER

The Caribou aircraft has twoseparate engine fire extinguishing systems, one for each engine. Pulling the FIRE-PULLT-BAR handle on the emergency panel releases the extinguishing agent into the enginenacelle and wheel well of therespective engine. If a secondshot is required, the extinguisher for the other enginecan be used by turning thehandle to the left and pullingagain. This may be more effective if done at reduced airspeed.

CLE N UPThe c 0 c k p i t should becleaned up according to the procedures already described un-

der single-engine shut-down.GENER L

Care should be taken that anactual engine fire exists beforeexecuting this procedure. tmay be a malfunction of thefire detection system that hascaused the fire warning lightto come on. The best check isto make a visual inspection onthe affected side; visible smokeor fire is sufficient cause forputting the engine fire procedure into effect.Sometimes the fire warninglight will come on for zone 1,which is forward of the auxiliary firewall, due to an overheatcondition. This usually occursduring c l im b u t at higherpower settings. ed u c i n gpower may eliminate the overheating and the fire warninglight. If the light goes out,the probable cause is a crackedor broken exhaust stack. Theimmediate emergency has beensol v e d; however, prolongedflight should not be attempted.Further damage may result ina serious emergency. Land assoon as practical and repair thedamage.

EXPECT THE UNEXPECTEDOne further word is necessary regarding single-engineflight. The Army does a lot ofunit training and the pilotsused as instructors are not always experienced as instructors or standardized in their

procedures. t may be well forthe regularly assigned instructors to pass on some of theirexperiences in this field.Always expect the unexpected. This is the cardinal rulefor instructors. If the wrongengine can be feathered, someone will feather it. As a matterof fact, nearly every student ina twin-engine transition course

will feather the wrong engineat least once during his training. Knowing this, the instructor should maintain constantvigilance and anticipate thestudent's action. He shouldalso plan what he will do insuch a case.Here are some e x amp I e swhich illustrate the instructor's problems:(1) The pilot failed to takeany corrective action whengiven a single-engine on thetakeoff roll; the YAC-1 continued to accelerate and wouldhave become airborne if the IPhad not taken over.

(2) The pilot raised thelanding gear when given a single-engine on base leg; IP hadto initiate a go-around on finalapproach.(3) The pilot had just leveled off at 8,000 feet and put theY AC-1 in the landing configuration to simulate a go-around.As power was reduced, heglanced down at the left thrustmeter, saw it indicating zero,and feathered the left engine.When asked why he did this, heglanced at the right thrustmeter, saw it reading zero, andimmediately a t tern p t e d tofeather the right eng i n e.BOTH ENGINES WERE OPERATING NORMALLY UPTO THIS TIME. If the IP hadnot taken over, both engineswould have been feathered.( 4) W h i 1 e practicing recoveries from unusual positions, the pilot was given asingle-engine during an approach to a stall; when powerwas applied on the good engine,the aircraft went into a violentroll.These are just a few examples, but I think they show beyond a doubt that the instructor should expect the unexpected. D


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THE MPORTA E

THROUGHOUT his trainingand his subsequent flyingcareer the Army Aviator isconstantly reminded of the importance of planning in advance. Practically every dayhe is told: "Plan ahead " It isdrilled into him by rote.

When a thing is constantlyrepeated it sometimes losesthe force of meaning and descends to the level of the subconscious. Now this is fine forskills which must become automatic to be most effectivelyperformed, such as the mechanical art of flying an air-plane. But the planning whichan Army Aviator must dothroughout all phases of hisjob should never become auto-matic performed w t h u tthought. The Army Aviatorand for that matter any Armyofficer must learn to bring allthe mental powers at his command to bear on the planningwhich he does.

For this reason it is usefulto emphasize the importance ofplanning to make sure that itis practiced at the conscious

Robert M Dickinsonlevel of the mind. Moreoverthe necessity for planning hasincreased significantly sincethe beginning of World War II.Today we are faced with an almost paradoxically perplexingsituation in which events occur much faster than ever before and there are more (andharder to understand) vari-ables determining the chain ofevents. This means that decisions must be made muchfaster while requiring muchgreater and more thoroughmental effort.

How can we expect an ArmyAviator for instance to makea decision more rapidly andyet think it through muchmore carefully than he wouldhave done 19 years ago? Par-tial answers to a question ofthis type exist on a largerscale such as in the carryingout of national strategy. Giantelectronic brains can augmentand speed up the thought processes of the decision-makers inthe Pentagon. But the individual officer faced with similarproblems on a smaller scale

can hardly carry an electroniccomputer in his aircraft or onthe front lines.

Traditionally there were twoapproaches to the problem ofdecision-making in an actionsituation. The first dependedon the individual thinking fastenough to consider all the vari-ables and coming to a decisionin time to take action. Thisworked in many fields frombusiness to sports, where i t isnot possible to establish in advance a standardized approachto every situation. But inmany of these same fields thisapproach is no longer satisfac-tory. Several years ago anEastern college had a starquarterback, who according totheir coach could never makethe big time. t seems thatthe quarterback had to thinkabout everything he did in-

A form er flight instructor whileon active Army duty Mr. Dick-inson is now employ ed by theEsso Research and Enginee ringCompany, Linden, N. J. f e alsoserves s an aviator with the NewJ ersey Army National Guard.5


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SEPTEMBER 1961stead of doing it automaticallya split second faster. He wasgood enough fO r their league,but modern sports being whatthey are, he wouldn t have beenable to make decisions fastenough in the Big Ten or profootball.

The second approach was totrain the individual to reactautomatically, without think-ing consciously in a problemsituation, by having him prac-tice stimulus and reaction overand over until his reflexes wereconditioned. Thus, the constand drilling in offensive anddefensive plays by crack football teams. An example evencloser to Army Aviation is thepractice in forced landings thatevery aviator remembers fromhis primary flight training. Theengine is cut in many differentsituations, until practically allPO ssible emergencies are covered and the proper emergencyprocedures become automaticto the pilot.

The second approach is stilleffective and will continue toremain so in many situations.However, as problems becomestill more complex, as the risksof emergencies or the dangersinvolved in actually goingthrough the emergencies grow,the necessary practice becomesmore complex, difficult, and expensive. For example, comparethe complex jet cockpit simulators of the Boeing 707 or Convair 880 with the World War IILink trainers.Ultimately both approacheshave limitations. In many sit-uations human minds simplycannot think fast enough to beable to think through all thefactors involved in a decisionand take timely action. Inmany others, there will be noway of simulating a realisticversion of the situation for re-6

flex conditiQning. More significantly, reflex action, even whenconditioned, is frequently notthe correct action in a particu-lar set of circumstances (suchas those met in modern war-fare) .The answer, obviously, isplanning - of the right kind.Individuals must learn to thinkahead even more than is donenow. The approach prO Posedhere is to forecast every possible alternative in particular situations, think through in advance the best action for eachalternative, and then set up asystem so that when any ofthe alternatives occur, theproper action or set of actionstakes place.

This is decision-making inadvance, when there is plentyof time to consider all the vari-ables and the decision-makercan use all the resources of hisconscious mind instead of depending on subconscious re-flexes. A probability weight-ing, either formal or informal,of the various alternativeswould be useful in allocatingresources in advance. On alarge scale, with modern computers, the forecasting processcan become very sophisticated,cover many variables, and goseveral steps into the futurebeyond the first action-reaction. But even the individualArmy Aviator can utilize thisapproach (which may be viewed as a much-refined version ofb 0 t h traditional approachescombined), but it would begreatly simplified, with a lotless high-powered technical assistance and sophisticated techniques available.

What has been said so far isnothing really new - ratherit is a change of emphasis. At-tention is focused to a greaterextent on the importance of

two elements: 1) the need forplanning in greater detail andto a much greater extent thanever before, and 2) the needfor a truly workable system toput the plans into action.

Such a system must be ableto: detect and determine whatis happening, Le., which alter-native is actually occurring;with maximum possible speedput the proper, predeterminedcourse of action automaticallyinto operation; evaluate the resuIts; take new and different,but also predetermined and appropriate action; continue thisprocess until a predeterminedobjective is reached or a predetermined failure is realized.A great deal of research mustof course be done before a system of this sort can be developed for use at all levels of activity.

Although the primary intentof this brief article is to spotlight the importance of advance planning for the individual aviator, there are also implications for Army Aviationand the people involved in it ona much larger scale. BecauseArmy Aviation represents thehope for a revolutionary newconcept of battlefield mobility,the people in Army Aviationwill be in planning and forecasting for tomQrrow s army.They will be instrumental inhelping to evolve the new bat-tlefield concepts and principles,as well as the tactics and military hardware.The weight of this responsibility should emphasize to theArmy Aviator of today the importance of planning in advance before every major stepor action, of making it a conscious and continual process,and of doing the best and mostcomplete job of planning possible. D


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WhyNotTigers

UR ARMED FORCES aretigers, cO'mposed O f ag

gressive O'fficers and men. Tigers that win wars and keep thepeace. Men that knO w whatthey and their equipment cand0 .HO W ab0'ut the Army A viato'r? D0'es he have the confidence to do any job his ma-chine is capable 0'f? Have weby 0'ur teaching meth0'ds madehim one 0 f the 600 nO't to rea-S0 n why, shying away frO many maneuver or pr0'cedure notused in training ? Have wemade him feel that a flightevaluation board is waiting forhim if he S0 much as uses carburet0'r heat 0 n a IO W reC0 nnaissance, even if he feelsthere is a possibility of the car-buretor icing?I t is impossible t0 teach anaviator all the situatiO'ns hewill be faced with, but we mustteach him t0 think. An explanatiO'n shO uld be given onthe why 0 f all pr0'cedures.I am cO'ncerned about thesethings when I observe an L-19pilO t using 45 0 flaps t0 land O na 5,000 ft runway when thereis a DC 7 turning final. I amc0'ncerned when questi0'ns areasked like, How dO y0 U g0frO m a high recO n to a I0 W re-con ?Have all the standards designed fO r pres0 IO and primarystudents been given to rated

Gerald T Thorpeaviators as a must f0'r all sit-uati0'ns? In a contr0'lled cO'ursethe student pil0't is seldomfaced with unusual situationsand the pr0'cedures he learnsusually work. When they aren0't the best for the situati0'nhe is forgiven f0'r being a stu-dent. But sh0'uld a rated ArmyA viatO'r think and fly like a stu-dent for the remainder of hiscareer?

Is it possible t0 have t0 Omany don'ts without an explanation? I w0'ndered ab0'utthis when I heard an aviatorof 5 years experience say hehad never I0'oped an airplane.I forgot about the don'ts andnO'rmal training maneuvers andmy thO'ughts drifted back O verthe years. Back to a CA VUmO'rning and a J -3 Cub.

The air was sm0 O th, and farbelow the w0'rld I0'oked cleanand neat. My pulse quickenedas I shO ved the n0'se down. Ihad been thinking abO'ut thissince I solO ed a week past. Airspeed was building, contr0'lswere tight; now was the time.Back O n the stick, easy at first.

The w0'rld is dropping awayfrom the n0'se ; mO re back pres-sure and full thr0'ttle. Thegr0'und is nO longer in sight,0'nly blue sky; and I am tight inmy seat. LoO k back n0 W, watchfor the horizon; airspeed isfalling 0 ff fast, m0're back pres-sure. Here cO mes the W0 rld upside down and level with ywings; n0 W I see only ground.Ease off 0 n the P0'wer, relaxS0 me stick pressure. Airspeedbuilding; I can feel the c0'ntrolsbecO'ming alive again. Back tostraight and level, ease 0 ffmore back pressure, add powerto cruise and I have c0'mpletedmy first I0 op. I had met myfirst real challenge, and now Icould walk with pride al0'ngside the 0'ld pil0'ts. As longas I lived by the f0'rmula andthe rules of the rO ad, the skywas mine.Since that day in the past, I

Mr. Thorpe is an instructorpilot in the Standardization Divi-sion Dept of Adv F j W TrainingUSAAVNS H e is fixed wingqualified with approximate ly 8 500flight hours.


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SEPTEMBER 1961have not only practiced thenormal training maneuvers butthe ones I heard about orthought of. How slow can I fly?Slower than the wind at times.Ever stood still or actuallydrifted backward over theground? How fast can I landon the wheels and stay down?One-wheel landings, landing ina turn, takeoffs at less thancruise power to simulate aheavy load or possible loss ofrpm in a climb-out, dead sticklandings from every alt i tudeI practiced any maneuver tohelp me master my machine.Early in my career I purchased a Steerman PT-17 andwith it a book on aerobaticswritten by an RAF colonel.Some of those maneuvers werereal works of art. Ever hear ofa Pair of Spectacles (CubanEight flown inverted) ? I triedthem all, no spur of the moment things, but carefullythought out maneuvers and always keeping a safety reserveof altitude and visibility.

Why did I practice all ofthis, the maneuvers never attempted in normal flight? Anairplane is a tool, you say, togo from A to B or to accomplish a certain mission wheremedium turns, straight andlevel, climbs and descents areall that is necessary. I feel themore you know about your machine's capabilities and yourown, the better you can perform the job at hand. New possibilities for using the equipment are practical only if themen can meet the challenge.

Perhaps by simulating undercareful planning all the unexpected things that could happen on a mission, you will never have to explain what didhappen to an accident board orwhy the mission was not accomplished to your CO

Is safety stressed to thepoint of the I had better notfly, something might happenattitude? Low-level flying isof utmost importance to theArmy Aviator in combat ortactical flying; yet we hear,Don't fly low; your enginemight quit. Let's tell the rifleman, Don't use your weapon;it could jam.No need to exceed the designlimits of the airplane. Howlong past, or have you everpracticed turns holding thesteepest bank possible? Orhow about slow flight, justabove stalling, or accuracylandings from all altitudes?How about slips and slippingturns, turning approaches?If you are floating too faron landing, would you raise theflaps or add more? Why nottry it on a long runway andfind out the best technique.Overshooting where a goaround would end up in thetrees is a poor time and placeto experiment. Which is thebest technique for takeoff fromdeep snow, mud or high grass?Why not practice three-pointtakeoffs with and withoutflaps? See which feels the bestto you. Maybe someday youwill have t land in the sameconditions. Have you practiced

three-point landings with power on during touchdown androll out?What if your mission callsfor a landing and takeoff on thecurve of a road? Ever practiced turning landings or takeoffs?Most aviators are by naturefree thinking, competitive peopIe; they would not love flyingif this were not so. Let's keepthe pot from boiling over, butby all means let's keep it boiling. Let the imagination go.There are many safe maneuvers to do, and generally thereare several right ways to dothem.My soul is stirred and I glowwith pride to be a member ofthe Army Aviation Schoolwhen I fly with young ArmyAviators like the lad awhileback. On a check ride he landed past his go-around point ina situation where a go-aroundwould have been a disaster,saying he would rather bust acheck than bust his posterior.Now there was a thinking man.The spark is there; let's keepit glowing.

t is not the author's intent tocondone unauthorized flight maneuvers in aircraft placarded againstsuch maneuvers. Aerobatics shouldbe confined to those permitted bythe aircraft handbook. - Editor


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Personnel Training ProgramCOMBAT EFFECTIVENESSof Army aircraft depends.to a large degree on the quality, as well as the quantity, ofmaintenance personnel available to the field. During WorldWar the Army used small,simple - to - maintain aircraft.These aircraft were organic tofield artillery and performedobservation type miss ions. Thisequipment was effectivelymaintained by mechanicstrained to work on the engine,rig the controls, repair component parts, repair the fabric,and perform in general all theorganizat ional maintenanceconnected with the aircraft.Tools were not always the best;in many cases, field expedientshad to be used.

As Army Aviation expandedand aircraft became organic tothe various combat arms andtechnical services, additionalmissions generated a requirement for aircraft that could flyfaster, farther, higher. andcarry larger payloads. To satisfy all requirements, moreand larger fixed and rotarywing aircraft were introducedinto the system.

The Army is currently authorized two categories of aircraft, the airplane and helicopter; and three types of aircraft, observation, utility, andtransport. They range fromthe small observation type(L-19, H-13) to the mediumtransport aircraft (AC-l, H-37). Each of these aircraft hasadd e d certain maintenancecomplexities into the system.As the model and number ofaircraft increased, the requirement for additional trained

Lieutenant Theodore S Chase TCmaintenance personnel also increased.

By approval of the Secretaryof Defense in 1955, the Armyassumed the responsibilitiesfor depot maintenance and supply. Actual transfer of responsibility came in July 1957. In1956 the Army assumed fullresponsibility for the trainingof aviation mechanics. In aneffort to stay abreast of theincreasing maintenance requirements generated by thepresen Army aircraft, a systematic program of trainingmaintenance personnel ha sbeen developed.

The mechanic who was capable of maintaining all aircraftin the Army inventory has vanished. The complexity of modern aircraft necessitates thatpersonnel be trained as specialists in a specific type aircraftand also in aircraft components.The training of aircraftmaintenance personnel is accomplished at the U S. ArmyAviation School, Fort Rucker,Ala., and at the U S. ArmyTransportation School, FortEustis, Va. The Army A viation School trains mechanicsfor the accomplishment of organizational maintenance whilethe Transportation S c htrains repairmen to accomplish field maintenance onArmy aircraft and aircraftcomponents.Some of the objectives of theArmy aircraft maintenancepersonnel training program areto:1. Provide the Army withqualified personnel to maintainall types of Army aircraft andaircraft components.

2 Establish a program thatreadily lends itself to expansion.3. Provide a system that canr a p i d y identify personnelqualifications.4. Establish a systematicmethod of training personnelon a need basis.5. Provide a career programin aircraft maintenance for enlisted personnel.

AR 611-201, Manual of Enlisted Military OccupationalSpecialties, dated 15 June1960, provides an interestingapproach to the aircraft maintenance personnel career program. The following information is based on this AR.Figure 1 depicts the militaryoccupational specialties associated with the Army aircraftmaintenance program. Thediagram denotes a progressivecareer pattern that begins atthe left side of the chart. Bothorganizational and field maintenance MOSs are included. Theentry MOS for the aircraftmaintenance career field is 670 ;and 680 is the entry MOS intothe aircraft component repaircareer field.MOS 670 qualifies an individual to enter the aircraft maintenance career program. In theupper left-hand block of figure1 are listed the various 67series (Military OccupationalSpecialties) that are scheduledfor inclusion into the organizational maintenance aircraftprogram. These are schooltrained MOSs that are taught

Lt Chase is a project officerwith the Dept of Ma intenanceUSAAVNS H e is fixed wingrated and instrument quali fied

9


12/40

2 AIIICRAFT.3 QUALIFICATION .4

671 SINGLE, ENG .6 AIRP . MECH .

FIELDMAINTENANCEREPAIRMAN

TECHNICAL

REFERENCE: AR 6112 115 JUNE 1960

7 672 MULTI ENG INSPECTOR .6AIRP . MECH . MAINTENANCE

675 SINGLE ROTOR .4 FIXED WING SUPERVISORHEL MECH .5 ROTARY WING SECTION676 TANDEM ROTOIl

HEL MECH677 MULTI ENG

HEL MECH

.2ALLLEVELSOF

CHIEF

ASSISTANTREPAIR

.7MAINTENANCESUPERVISOR

PLATOONSGT

REPAIR

.1

681 ENGINEREPAIRMAN

TECHNICALINSPECTOR MAINTENANCE FOREMAN FOREMAN

682 CARBURETORREPAIRMAN

683 POWER TRAINREPAIRMAN

614 ROTOR/PROP

FORCOMPONENTREPAIR

SECTION 67 9.7CHIEF

67 9 .6REPAIRMAN

615 ELECTRICAL\0 REPAIRMAN

686 AIRFRAMEREPAIRMAN

687 HYDRAUUCSREPAIRMAN

688 INSTRUMENT. REPAIRMAN

~1--------

at the Army Aviation School.Upon completion of this training and after obtaining fieldexperience in the selected MOS,the mechanic has an opportunity to, apply for further schooling as a field maintenance repairman (listed as a .4) or byvirtue of experience and promotion, advance into an organizational maintenance supervisor position.A mechanic who elects toadvance directly to .6 may continue in the organizationalmaintenance career programthrough .9, or sergeant major.His advancement is dependentupon field experience and promotional opportunities.A mechanic who elects further school training in the .4field maintenance repairmanprogram will receive this training at the TransportationS c h 0 0 1 Fort Eustis, Va.10

FigureCourses have been establishedunder the same MOS titleslisted in the upper left-handblock. Upon completion of oneof the repairman s courses, theindividual will most likely beassigned to a field maintenanceorganization for experience.

The successful completion ofa .4 repairman course qualifiest h e individual for furtherschool training as an AircraftRepair Supervisor - Inspector,MOS 679. Individuals who havespecialized in fixed wing aircraft will continue into the679.4 course, which will qualifythem as fixed wing aircrafttechnical inspectors. Similarly, a specialist in rotary wingaircraft should continue on into the 679.5 course and becomequalified as a rotary wing technical inspector.

The aircraft technical inspector MOS is now being included in the tables of organi-

zation of aviation units that areresponsible for organizationalmaintenance as well as intounits that perform aircraftfield maintenance. Upon graduation from the .4 or 5 course,the mechanic may be assignedto either of these type organizations.Advancement in the 679

.9 4823

FIRST SGT ACFT MAINTSOT MAJOR OFFICER

67 9 .8 67 9 .9

career field will require the individual to receive additionalschooling. The TransportationSchool teaches a course concerning maintenance management. Upon completion of thiscourse, the individual will qualify as a 679.6 and be permittedto advance in the 679 careerfield.

The 68 series (Military Oc-cupationaL Specialties) aircraftcomponent repair courses areall taught at the Transportation School. A 680 entry courseis not taught. Instead, an applicant enters directly into oneof the specialist type courseslisted in the lower left-handblock of figure 1. A graduate iseligible for assignment to afield maintenance organizationthat requires this specializedtype MOS. At a depot or specialtype of unit, an individual inthis career field may advanceto a technical inspector forcomponent repair. This assignment would qualify the individual for a .2 designation to hisMOS.The right-hand block in figure 1 is entitled 4823, Airc r a f t Maintenance Officer.The responsibility to trainthese officers is vested in theTransportation Corps and acourse is presented at the


13/40

ORG NIZ TION L kH1W?1FIELD

BOTHAIRCRAFT M INTEN NCE

67

Transportation School. Selectedofficers of the combat arms andtechnical services attend andare trained to manage anddirect the operations of aircraft maintenance organizations and maintenance operatinns of aviatinn units.

Based nn AR 611-201, theArmy has devised a system toidentify an individual as to hismilitary nccupatinnal specialtyand the type aircraft which heis qualified to maintain. Thisinfnrmatinn is depicted in figure 2.

The left-hand column of figure 2 is a list of the militarynccupatinnal specialties authnrized for aircraft maintenance.An nrganization maintenancemechanic trained in nne nfthese MOSs will be further

QUAlIFICATlONS

~ ' f Ci . ,... . . , ~ ~ : ..:: ~ ~ A :: :

Lal .,

:: :::: l ::: :::::;r + + .4+ + + 1-

,.

+++++ +++ + - + +++ + + ++ + ++ + + ++ + + ++ + ++ LL ++ + ++ + + ++ + ++ + + +

c .,>,

W I I N G I ~ SS Tl REP REPAIR- + 679,.7 + + 6 ~ 9 8 +1< , . ~ ~ f A ~ n p ~ M . I I . . I + + + . + + +

~ ~ ' + + + + + + + + + + + + + + + + +Figure

identified by a .1, .2 or .3 attached to his MOS. This designation will identify the typeaircraft that the mechanic isqualified to maintain. Fnr example, a 672.3 is qualified tnmaintain multiengine mediumtranspnrt airplanes. The ArmyA viatinn School, which is respnnsible f 0' r nrganizationalmaintenance training, anticipates that personnel enteringthe program from the basic 670course will be initially trainedas either a 671.1 nr a 675.1. Amechanic trained as a 671.1will then be eligible to advanceto a 671.2 or into the 672 field.A mechanic trained as a 675.1will be eligible to advance tn a675.2 nr .3 or to a 676.1 nr677.1.

Mechanics who elect to re-

ceive schnoling in field maintenance will be trained on alltype aircraft that are a responsibility nf a particular MOS.This is depicted in the columnof figure 2 entitled .4, FieldMaintenance Repairman. Theremainder nf figure 2 shows theprngressive career programavailable to the personnel assnciated with aircraft maintenance.

The training nf Army Aviation maintenance personnel is agreat responsibility. With theadvent of mnre complicated aircraft and compnnents, it hadbecome necessary to develop atraining prngram fnr maintenance personnel so that ArmyAviatinn cnuld further expandand effectively and efficientlyaccnmplish its many and variedmissinns. D

11


14/40

afelyin CTIONWilliam E Carter

T S ONE THING to sit behind a drawingbo.ard day after day preparing illustratio.nsand layo.uts for accident preventio.n publica-tio.ns but the o nly way to get clo se to the realArmy Aviatio.n safety picture is to visit unitsin the field and see safety in actio.n. RecentlyI had the o.PPo.rtunity to do just that and ito.pened my eyes. During a tour o f the Pacificarea, I visited Army Aviatio.n units in HawaiiKo.rea and Okinawa. The purpo.se o f my tripwas to obtain a view o f Army Aviatio.n units their missio.ns and the vario.us types o f terraino.ver which Army aircraft must o.perate.

12

Thanks to the ho spitality and genuine interesto f USARPAC aviatio.n personnel the trip wasa co.mplete success. I returned with firsthandkno.wledge which will help me greatly in pre-paring illustratio.ns of Army Aviatio.n. I re-turned with a great new re spect fo.r the ArmyA viato.r in the field.

Mr . Ca rter s the illustrator for the LiteratureDivision of US B R. His illustrations are fre-quently seen on the pages of the U S . A RMYA VIA TIO N DI GE ST. H e is responsible for thismonth s Gover and the illustrations contained inthis article.


15/40

The first leg of my journey carried me toHawaii. There Lt Col Robert M. Rawls G 3aviation officer USARPAC and his assistant,CWO Keith Glasgow briefed me on what toexpect at the various units I would visit. FortShafter, USARPAC Headquarters, is the fountainhead of accident prevention material forthe entire Pacific area. Army safety publications including the U. S. ARMY AVIATIONDIGEST and similar publications from theother services are funneled through ColonelRawls to the aviation units in the field. It wasgratifying to see the high priority accorded thismaterial.Then it was on to Korea. We landed atKimpo Air Force Base and I was met by Mr.Clark C. Bohannan 8th Army Aviation safetyofficer. A former Army major and masteraviator, Mr. Bohannan is a graduate of theArmy Aviation Safety Officers Course at theUniversity of Southern California. He is fixedwing and rotary wing qualified. Mr. Bohannanescorted me to 8th Army Headquarters wherewe met Col Jack K. Norris aviation officer.Colonel Norris gave me a thorough briefing on

SAFETY IN ACTIONthe itinerary he had arranged for my stay inKorea. t was apparent that considerable timeand thought had been given to my schedule sothat I could get the most out of the week Iwas t spend in the Land of the Morning Calm.The following day Mr. Bohannan and Iboarded an H-13 Sioux and flew to NightmareRange. The 1st Cavalry Battle Group was conducting Army training tests exercises supported by the 15th Aviation Company and 13thHelicopter Company. Lt Col Robert E. Triggcommander 15th Aviation Company met usand briefed me on the various types of missions they were performing. Flying over someof the most rugged terrain I had ever seen wewatched H-21 Shawnees deliver combat troopsto hilltop positions. And this was where Istarted to see safety in action.Regardless of an aviator s past experiencewhether he has 500 hours or 5 000 when hereports to an 8th Army aviation unit he isimmediately given proficiency training. No aviator is assigned a mission until he can proveto a demanding check pilot his ability to copewith terrain hazards and the 40-knot winds

13


16/40

common in Korean mountains. He is trained tofly through the dust Qf his rotor wash and mustdemQnstrate an accurate knowledge of weightand balance and the effects of high density altitudes. Only when he has mastered all thetechniques required for mountain flying anddemonstrated expert judgment and kno.wledgeis he considered ready to fly missions for hisunit.This training was evident in the flights wesaw that day. After the Shawnees had delivered all of the troQPs into positio.n, they wereflQwn back to. Alpha 35 where they picked upsling loads of supplies and delivered them tothe hills. We saw H-13 Sioux laying wire fromthe ridge crests down to the command postand we watched an H-19 Chickasaw performthe medical evacuation of a soldier who had

broken his leg. Some of the landing sites usedby the aircraft perfo.rming these missions wereamazing. Frequently there was only room toget the wheels o.n the ground. One Shawneeaviator to.ld me it was not unco.mmon to landon ridges with only the rear wheels touchingand the front wheel hanging into. space whiletroops were disembarked or loaded.Mr. BQhannan flew me to. Alpha 9 the nextmo.rning and Colonel Trigg arranged an L-19Bird Dog flight for me to. tour the DMZ DeMilitarized Zo.ne). We flew along the 38thParallel and looked acro.ss no. man s land intoco.mmunist KQrea. My pilo.t, a yo.ung lieutenant,14

knew the country like it was his own backyard.You have to. when a violatio.n o.f the boundarycould mean an ugly international incident.caught glimpses of the white tape along theedge Qf the DMZ and breathed a frank sigh o.frelief as we turned back toward Alpha 9.On Tuesday Mr. Bo.hannan flew me to. Alpha160 fo.r a visit with the 1st Co.rps artillery.There, we observed Bird Dogs directing fire of155 mm ho.witzers and performing messagedrQPs. These aviato.rs, as well as all the otherssaw during the complete tour, handled theiraircraft over horrendo.us terrain as tho.ugh theywere flying over the flat peanut patches o.fSo.uth Alabama.spent that afternoon at the ASCOM Maintenance Depot, where Capt Densmore Henchel,maintenance o.fficer, showed me aro.und andbriefed me on the activities Qf the 55th Trans-portation Company. Aircraft mechanics, noless than aviato.rs, must undergo. thorough indoctrinatio.n and training befQre they are readyto perfo.rm their missiQn in KQrea.Wednesday, it was up to Alpha 161 and avisit with Maj William L. Duncan, commander,13th TransPQrtation CQmpany. Majo.r Duncanarranged for me to fly to Camp HQvey whereobserved practice troo.P Io.ading and unloadingof H-21 Shawnees. was taken to. the 4th Missile CQmmand, K-47, fo.r an L-20 Beaver tourof the Punch BQwl are31 and helico.pter trainingsites. On Thursday visited Lt Col Frank E.


17/40

LamQthe aviatiQn Qfficer 7th DivisiQn and sawdemQnstratiQn launchings and recQveries QfradiO cQntrQlled drQnes. Again my strQngestimpressiQn was Qf the cQmpetent manner inwhich all the aviatiQn persQnnel performedtheir missiQns under the mQst difficult circumstances. These were real prQfessiQnals and theway they did their jQbs spelled safety in actiQn.

In every QperatiQns Qffice, regardless of hQWlarge Qr hQW small I saw aircraft accident preventiQn material - periQdicals accident accQunts pictures PQsters sense pamphlets werecQnspicuQusly displayed. An aviatiQn safetybulletin bQard was in each Dffice. These bQardswere well kept and filled with current material.What the aviatiQn safety Qfficers don t getthrQugh channels they make up themselvesand the locally prQduced material shQwed realimaginatiQn and talent.One Qf the highlights f my visit was attending the monthly aviatiQn safety meetingat 8th Army Headquarters. CDIQnel NQrrisQpened the meeting with a discussiQn Qf twOrecent accidents caused by fuel cQntamination.Maintenance persQnnel then reviewed CQrrectprQcedures in fuel handling to prevent cQntaminatiQn by dust. This is a CQnstant hazard inKQrea and Qne that will becQme mQre criticalwith the advent Qf the HU-1 IroquQis and JP-4fuel. An Air FQrce weather Qfficer gave a brief-

SAFETY IN ACTIONing cQvering the weather expected for the nexttwO mQnths. Visual aids were used for all thebriefings and they were presented in a waythat captured and held the attentiQn Qf allthQse present. ColQnel NDrris infQrmed me thata new policy will call fQr all unit aviatiQn safetyQfficers to attend a regular mQnthly meetingin SeQul fQr standardizatiQn f mDnthly meetings thrDughQut the cQmmand.

The t ur next carried me to Okinawa. CWOJames A. Bartley, aviation safety Qfficer 53dAviatiQn Detachment, met me at Kadena AirFQrce Base and took me to meet his cQmmander Maj RQbert L. Runkle. MajQr R unkle gaveme a briefing and arranged an HU-1 IroquoistQur of the island training sites. The terrainQn Okinawa while nQt appearing as rugged asthat in KQrea presents new and difficult prQblems fQr aviators whO fly Qver steaming junglesand mQuntains. One Qf the majQr hazards toaviatQrs Qn Okinawa is the dense air traffic.The island is like a giant aircraft carrier, withair activites Qf all three services crQwded intOits 910 square mile area. Here again ArmyAviatQrs demQnstrated the prQfessiQnal CDm-petence that I had seen thrQughDut the Pacificarea.I left Okinawa hQmeward bound convincedthat I had seen the best - I had seen aviatiQnsafety in actiQn.


18/40

Autorotational Characteristics andRecovery Altitude Requirements

for the HU lA Helicopter

N OCTOBER 1959 a U. S.Army Aviator was inj uredand a U. S. Army HU-1A helicopter demolished while making an autorotation landing.Official accident reports state,and photographs show, thehelicopter contacted the groundwith an excessive rate of sinkas the pilot was effecting a recovery from an autorotationlanding. t was concluded thatthe pilot initiated the maneuverat too Iowan altitude; consequently, the recovery to levelflight was not fully completedwhen the aircraft crashed. Assuming the pilot correctly readhis altimeter, the accident is acase of the pilot misj udging theautorotational character of theHU-1A helicopter.The purpose of this article is1) to describe the HU-1Aautorotational characteristics,recovery altitude requirements,and recommended autorotationprocedures in order to preventfuture accidents of this typeleading to possible inj ury, lossof life, or aircraft damage, and2) to re-emphasize that HU-

Mr . McWilliams is Chief De-velopment Division; Directorateof E ngineering wi th the U. S.A rmy T ransporta tion Materiel

mmand St Louis Mo.

6

Bayard T. McWilliams

1A pilots should be completelyfamiliar with that portion ofthe pilots handbook applicableto this subject.AUTOROTATIONALCHARACTERISTICS

The steady state standardday) rate of descent of the HUlA helicopter in steady autorota ion is shown in figure 1Also presented for comparisonis the rate of descent for theH-13 type helicopter. As canbe seen the minimum rate of

descent for the HU-lA is approximately 34 percent greaterthan for the H-13. In additionif the HU-lA is nosed down tothe angles normally used in theH-13 for autorotation, the indicated airspeed will increaseappreciably and rates of sinkof 3,400 to 4,000 fpm maydevelop.

This condition can normallybe expected with the HU-lAwhenever abrupt nose - downmaneuvers are executed duringautorotation. Nose-down div-

Figure 1RATE OFDESCENTFPM)3000

2000

1000

STEADY STATE AUTOROTATION RATE OF DESCENT

GW 5800 LBS

GW 2270 LBS

~ 20 40 60 80 1CALIBRATED AIRSPEED KNOTS)


19/40

AUTOROTATIONAL CHARACTERISTICS

200

>- 1 54 Gor> GW 6400 LBS0 150oror2 1 70 GS GW 5800 LBS NOTE:r5 CONSTANT G2or 100 RECOVERY1 90 G

GW 5200 LBS

INITIAL RATE OF DESCENT FPM)

Figure 2

ing turns also produce thesame high I'utes of descent.Rates of d e ~ c n t of this magnitude repre6ent an increase ofalmost 200 percent over thoseexperienced in the H-13. Whenever maneuvers are executedresulting in these rates of sink,approximately 600 feet of altitude is lost with the HU-IAduring the period when thehigh rates of descent build up.STEADY STATE STANDARD

DAY) UTOROT TIONRATE OF DESCENTThe higher rate of descent inautorotation of the HU-IA results primarily from its higherdisc loading aircraft weight

per unit rotor disc area). Thedisc loadings of the H-13 andHU-1A are approximately 2.5and 4.0 pounds per square foot

respectively. As the trend inhelicopter design is towardhigher disc loadings, this characteristic will become morecritical.

RECOVERY LTITUDER QU I REMENTS

The altitude required to effect a successful recovery tolevel flight for various rates ofdescent is presented in figure2. These altitude requirementsare presented for constant g recoveries of 1.54, 1.70, and 1.90which represent the maximumload factors attainable on theHU-1A for gross weights of6,400, 5,800 and 5,200 poundsrespectively. The data shownon this figure allows one secondreaction time for the recoverymaneuver. It should be notedthat the altitude required to

recover is a function only ofthe initial rate of descent andnot of the initial airspeed.Considering both the altitudeloss while the rate of descentis building up and the altituderequired to recover, a minimummaneuver initiation altitudeabove the terrain of approximately 800 feet is required ifmaximum rates of descent areexpected.RECOMMENDED PROCEDURE

The recommended autorotation procedures to avoid highrates of descent and execute asafe recovery are as follows.

(1) Until familiar with theautorotation characteristics ofthe HU-1A, enter autorotationat no lower than 1,000 feetabove the ground.(2) Upon entering autorotation from cruise flight, it is

generally good practice to holdthe nose up until the airspeeddecreases to approximately 55knots.(3) Stabilize the airspeed at

55 knots. The rate of descentis approximately 1,800 fpm at314 rotor rpm.(4) At approximately 20 to25 feet above the ground, exe

cute a flare to reduce the airspeed and rate of descent.(5) Turns may be executed

during autorotation but extreme care should be taken tokeep the airspeed from increasing.R E M E M E R _ Becomefamiliar with your pilot's operating handbook. 0The Department of Rotary WingTraining, USAAVNS, recommends60 kIliOlt airspeed for autorotationsand 70-100 feet of altitude forflares. - EDITOR

17


20/40

IROQUOIS H-34 CHOCTAWH-21 FORWARD ROTOR BLADE damaged bypart of tent which was either pulled or thrownout cargo door while aircraft was idling at 1600rpm .H-13H STRUCK WIRE with tail rotor while air craft was making hovering turn from taxiway topark . Aircraft spun to right approximately onecomplete turn then landed. Cross tubes brokeat touchdown and aircraft came to rest on leftside of engine mount and right skid . Majordamage. No injuries .H-23D ENGINE RAN ROUGH during cruisefl ight at 500 feet . Power approach was madeto open field and aircraft landed with no damage .Piston in No . 6 cylinder failed due to brokenring band .H-21 C ENGI NE RAN ROUGH and lost power inf l ight . Aircraft completed forced landing withno damage. Loss of power caused by failure ofphenolic gear in left magneto.H-23B ENGINE FAILED during landing ap proach. Main rotor blade flexed into and severed tail boom at touchdown . Major damage .No injuries . Cause of engine failure undetermined pending investigation .HU l A PITCH CONTROL partially lost in f l ight .Aircraft completed forced landing with no apparent damage. Lock plate PI N 1560-624 -6720on scissors assembly PI N 1560-624-5150 failedallowing nut PI N 5310-788-0048 to disengagefrom hub . This allowed scissors assembly to riseand increase collective pitch .AO-l AFT NACELLE COWL tore loose in fl ight .Incident damage. No injuries.

H-23 RAVENHU-1A TOUCHED DOWN tail low from prac tice autorotation during transition training f l ight .Aft portion of skid contacted ground first. Air craft bounced into air and main rotor bladeflexed downward severing tail rotor drive shaftand partially severing tail boom . Major damage .No injuries .HU-l A LANDED HARD from practice autorotation . Skids collapsed; bottom of fuselagebuckled; and antenna damaged. No injuries .Hard landing caused by slow airspeed and slowpitch application .H-21 C H I P DETE TOR LIGHT came on duringf l ight . Aircraft completed descent and landingwith power. No damage. Metal particles foundon screen and engine sump plug.H-13H TAIL ROTOR STRUCK GROUND duringflare at end of practice autorotation. Tail rotorblades, gear box and short shaft damaged. Noinjuries .L-19E TAXIED INTO TREE on road strip. Rightwingtip damaged . Overhead plexiglass broken.No injuries .L-20 LANDED SHORT of runway causing minordamage to tail cone assembly and tailwheel.H-19D MAIN ROTOR BLADES flexed downwardand severed tail rotor drive shaft after touch down from practice autorotation. Major damageto main rotor blades. No injuries .H-13E LOST POWER during flight. Aircraftcompleted forced landing with no damage. Sparkplug over intake value of No. 6 cylinder blewout , causing power loss.


21/40

AO-l MOHAWK H-21 SHAWNEE

L-23 SEMINOLE H-37 MOJAVEHU-1A LOST OIL PR SSUR in flight. Aircraftcompleted approach and landing with power.Oil pressure loss caused by broken oil line.H-37A ENGINE RAN ROUGH and backfired inflight. Shortly after takeoff loud explosion washeard from No. 1 engine which then began torun rough . Aircraft completed forced landingwith no damage. Preliminary inspection revealedcarburetor air intake duct swallowed . Suspectcontaminated fuel.H-23D STARTED with main rotor blade securedby mooring clamp. Incident damage to mercuryclutch drum friction shoes.H-23B ENCOUNTERED LOW CEILINGS whileflying up dead end valley. Aircraft made 1800turn to maintain visual contact with ground .During turn main rotor blades struck tree. Majordamage to main rotor blades. No injuries.L-23D L FT ENGINE made loud sound in flight.Fuel and oil pressure decreased. Propeller wasfeathered and aircraft completed forced landingwith no damage. Crankshaft counterweight assembly at No. 6 piston was thrown through topof engine crankcase knocking a hole from topof No.5 cylinder mounting base to top of No.6cylinder mounting base and shearing camshaft .Initial inspection indicates counterweight rollerretaining ring failed. This allowed counter weight roller to sl ide out and caused counter weight to be sheared in half.AO-1A L FT ENGINE made unusual noise infl ight . Propeller was feathered and aircraft completed precautionary landing with no damage.Cause of unusual noise unknown pendinganalysis .

L-20 BEAVER

AC-l CARIBOU H-19 CHICKASH-21C ENGINE LOST RPM during flight. Aircraft completed forced landing with no damage .Loss of rpm caused by internal engine failure .One valve seat was blown out through exhaustsystem.H-13H ENGINE FAILED in fl ight . Aircraft wasautorotated to only available forced landingarea which was a dirt road. Rotor blades strucktree pitching aircraft on its side and causingit to roll. Aircraft destroyed . Pilot and passenger sustained minor scratches. Cause of enginefailure undetermined pending investigation.L-19A TAXIED INTO sewer manhole. Incidentdamage. No injuries.HU-1A MAIN ROTOR BLADE and windshielddamaged during ground reconnaissance. Whileinspecting touchdown autorotation area instructor pilot found piece of metal and tossed i t aside.Piece of metal struck main rotor blade and wasthrown into windshield. Major damage. No in juries.H-13H TAIL ROTOR struck ground during steepapproach to confined area. Minor damage totail rotor tail rotor drive shaft and hanger bearings. No injuries .G-91 CRASHED during demonstrton JATO takeoff. Aircraft destroyed. Pilot employee of foreign aircraft firm killed .H-19D PITCHED UP suddenly into nose-highattitude without warning . Aircraft became extremely difficult to control and precautionarylanding was made on school playground . Nodamage to aircraft. No Injuries. Suspect temporary hydraulic system failure .

9


22/40

Y CO l n l n a n d

u v eillanceVehiclesPAST PRESENT FUTURECaptain Edward C. Kopeschka Arty

CURRENT AVIATION companies of the Infantry andArmored Divisions and Ar-mored Cavalry Regiments havedrone systems assigned to theirTOEs. A possibility exists thata system will be assigned tocorps and field Army Aviationunits. Army Aviation may alsobe responsible for the organization and development of dronecompanies for the Army. Theemployment and integration ofthis system by Army Aviationwill be closely b s e r v e dthroughout the Army.

Army Aviators currentlyhave the responsibility forcommanding and employingsections, platoons, and companies containing drone systems. Inasmuch as this re-quirement does exist, it behooves all of us to take a broadlook at the operation and employment of the current dronesystem and its future possibilities.

Through the centuries world2

civilizations have been constantly changed by evolutionary equipment developments.Military equipment by necessity has changed to stayabreast of global developmentsand to meet the needs of anation's security requirements.Today we are on the thresholdof conquering space. Modernworld powers are involved in arace to first conquer this area,thereby achieving an advantageous balance of power. Thepractical implications of aspace platform that can be employed for military purposescan scarcely be questioned. U sing over the top techniques,these vehicles will quickly expose military and strategic information with little expendedeffort. Current command controlled aerial surveillance vehicles should be considered onlyas an intermediate development stage for future vehicles.The terminology now associated with command controlledaerial surveillance v e h i c I e s

such as the missile rocket ordrone is comparatively new dueto their evolved origin . Definitions for these vehicles willvary with the dictionary usedand its date. Military dictionaries define the drone as apilotless airplane of conventional design, piloted by remotecontrol, and once airborne,guided by a mother aircraft.The 1960 Webster's New Collegiate Dictionary defines it asa pilotless aircraft, vessel orother craft, remotely controlledby radio. This last definitionthen we find more compatiblet our present and futurevehicles.

The history of the dronedates back to the 13th Centurydays of Marco Polo with hisdiscovery of Chinese black powder and related missile androcketry. The biggest advance-Capt Ko peschka is a project of-ficer with the Dept of T actics

US VNS . H e is fixed wingrated and instrument qualified.


23/40

Kettering Bug Schmetterling Butterfly

AERIAL SURVEILLANCE VEHICLES

(ballistic missile) experimental base.Also in 1943, the British discovered launch sites were beingprepared in France. However,it was not until late in 1944that the Germans began blitzing England with its V-I controlled bombs and V -2 controlled missiles. The primaryreason for this delay was thatGerman programs of development and production failed tokeep pace with establishedgoals.

V-I (F2G76) jet propelled drone. Speed 3 4 kt. Wingspan 17.7 ft.Overall length 25 ft. Used to bomb England and Antwerp, Belgium.

The V-I drone became knownas the buzz bomb, flyingbomb, stovepipe, and doodlebug. t was a pulse-jetpilotless aircraft, preset originally and in later stages radiocontrolled carrying a payloadof 2,000 pounds in its nose atspeeds of 347 kt. It was theforerunner to the V-2 whichwas a missile as we know it today. The V-2 was 46 feet longand 5 feet in diameter. Poweredby a liquid oxygen consumingengine, it carried a payload of1 ton for an approximate rangeof 300 miles at speeds of 2,608kt.

ments have been made from1914 to the present.During World War I, the airplane was developed as a mili

tary weapon. High loss ratioscaused consideration to begiven to a remotely controlledaircraft, which could be usedto bomb its objectives withoutendangering or sacrificing thelife of a pilot. Late in 1917,Charles F. Kettering, workingfor Sperry Gyroscope Company, successfully test flew twopilotless aircraft. By 1918, afull-sized aircraft was developed that could fly within 300feet of a target over a 40-milerange. The Kettering Bug,as the vehicle was called,weighed approximately 3 0 0pounds and was constructed ofpaper and c r d bo r d reinforced by wood cross members.The Bug was launched froma small platform equipped withfour wheels which rolled down

a portable track.During WW II England received rumors from varioussources that the Germans intended to use new weaponsagainst them. Convinced thatthese weapons existed the British took measures to counteract them in 1943. Late in 1943,the British bomber commandcrippled the Punemunde development base in the Baltic. twas later discovered that Punemunde was the main Axispower V-I (bomb) and V-2

Another German drone development was the Schmetterling B u terfiy HS-117, whichwas still in the test stage at theclose of World War II. Thisaircraft was a remote controldrone similar to those we havetoday. It was a small all metaldrone, with a fuselage lengthof 13 feet and a wing span of

SO 1 A surveillance drone used as aerial platform forKA-20 XM2) aerial camera


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Launch test area imagery ySD l drone with KA 39Acamera2 feet. Propelled by a liquidfuel rocket motor and tworocket boosters which jettisoned 5 seconds after takeoff,it had an effective range of 100miles at 459 kt.Now that we have established that drone developmentis not new, let us look to today smodels and their related capabilities, characteristics, andtypical employment.The surveillance drone one

(SD-l) is currently in aviationorganizations. I t is organic tothe aerial surveillance platoon(drone section) of the armoredcavalry regiment, infantry andarmored division aviation companies. It is a zero launchedvehicle, powered by a two cyclegas engine. Takeoff is assistedby two boosters which jettisonseconds after the drone becomes airborne. The operatingradius of this drone is approxi-22

mately 65 kilometers and isparachute recoverable. It presently performs photographicmissions and is remotely controlled by a combination beacon and radar (AN/ MPQ-29) .The radar control (AN/ MPQ-29) is a mobile system designed to plot the course andpresent position of the drone sothat it may be directed by

radio command over targetareas on surveillance missions.The system may be controlledby conventional radar (skintracked), or it may be used inconj unction wi t h a beacontransponder placed in t h edrone. An optical target selector provides a means of auxiliary observation and targetselection by a remote operator.The system employs two plotting boards which provide theplotting capability on smallscale and large - scale mapssimultaneously or on eitherscale separately. The system isvehicle mounted and equippedwith an electrically heatedshelter. Input power is supplied by a generator on a separate trailer. A crew of four,two radar- operators, a radarmechanic, and a controller, em-

ploy the AN / MPQ-29. This system can be put into operationin approximately 15 minutesby an experienced crew.The surveillance drone two(SD-2) is currently undergoingtests and is expected to replacethe SD-l. It is zero launchedby solid p r 0 p e n t rocketboosters from a standard military vehicle. Recovery is byparachute. An improved modelof the SD-2 is also under development. The SD-2 has attainedspeeds of 160 knots in less than2 seconds and climbs to an altitude of 2,000 feet in 35 secondswith a cruise altitude of 10,000feet.The combat area surveillancedrones three and f0 ur (SD-3and SD-4) , until recently underdevelopment for the U. S.Army, have been d r p p e d.However, these drones containsome desirable design characteristics which provided background data for our currentmodels under development andtest. Original proposals contained requirements for a jetpropelled drone equipped withselective packages consisting ofphotographic radar and infrared sensory devices.

Top: SD 5 Drone. Bottom: SD 4 Drone.


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AERIAL SURVEILLANCE VEHICLES

The surveillance drone fiveSD-5) is another of the newseries of information - seekingdrones. It is used as a part ofan airborne surveillance system and is equipped with anumber of sensory devices forreporting battlefield reconnaissance information.A QMR Qualitative Materiel Requirement) has re-cently been proposed for a midget drone system. This systemwould be used in combat areasto perfo.rm day o r night targetlocation fo.r division artilleryand certain missile commands.This system is desirable because it would reduce require-ments for equipment 34 to.ntransportable), maintenance,and operating personnel. Theorganizatio.n con c e p t wouldplace this system o.rganic to thetarget acquisition p a to.o n,Headquarters Battery DivisionArtillery, and the drone platoonField Artillery Target Acquisition Battalion FATAB).

These models, then, are a fewof the drone systems on whichwe will base our present andfuture usage. These systemsposses many desirable capabilities and characteristics. They

have the ability to observe atrelatively high speeds manymiles from the launch area.They are designed to providethe combat commander withimmediate co.mbat intelligenceand related weapons effects.Their fo.ur sensory packageswill permit radar, infrared,photo.graphic, and imagery detection. An additio.nal television package is being considered for future integratio.n.Certain of these systems canoperate day or night in allweather conditio.ns and are difficult to fool by camouflage.They are ground and air trans-portable, reco.verable, and willbe co.upled with automatic dataprocessing.The current mission o f thesurveillance drone is to act asan additional eye for the commander. t supplements groundand aircraft intelligence collectio.n efforts or replaces themunder untenable conditions dueto air or ground defenses orhigh loss expectatio.ns.Successful missions of thesurveillance drone is predicatedo n the development of a detai led plan. Dro.ne surveillancemissions, are divided into two

AN/MPQ 29 r d r control system

phases. The first phas,e consistsof the plan of employment.This includes route planning tothe launch area, launch areaselection, targets desired, flightplan route, equipment required,and recovery area selectio.n.The second phase co.nsists o fthe operational phase. This includes relocation, launch, flightmission, recovery and deliveryof the data to, interested agen-cies.A typical dro.ne missio.n withits criteria for employment isdiscussed next.

The radar AN / MPQ - 29)control system must be lo-cated in a position to o.btain aline-of-sight coverage abovethe target area and a returnpath for the drone. Whetherthe dro.ne is to be skin trackedor beacon tracked is a factorthat must be decided beforethe launch. Beacon track ismore desirable as it permits agreater tracking range. Equipment locations must take intoconsideration sound tacticalpractices to prevent destruc-tion.The launch area can beadapted to many locations because of the versatility of thelaunch methods and groundsupport facilities. Such locations include hilly, mountain-ous, wooded or other obstructedterrain which restrict the take-off of conventional aircraft. tis located well forward, as nearthe FEBA as the tactical situa-tion will warrant, to obtainmaximum capability from thedro.ne and its equipment. Thelaunch area must provide suf-ficient equipment and workingspace and must have alternateexits.

The radar and the controlstation will co.ntrol the dronewhile it is o.ver the target. Thisequipment is lo.cated so.me dis-


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tance from the launch area.For protective reasons, thisposition must be located to theflank of the launch area. Thedrone control transfer will bemade after the launch by thelaunch controller and the mission is continued from this distant point. Immediately following the launch, after theradar has locked on the drone,the radar controller will observe and control the drone spath on the radar plottingboards and maneuver it overthe target. Also, after thelaunch has been completed, thelaunch team and their equipment relocate to a predeter-mined position, thus prevent-ing possible destruction byenemy fires.

At the completion of the mission the drone is flown to thepredesignated recovery areawith control transfer effected,if necessary, and the drone isrecovered. The material obtained from this mission is im-24

mediately forwarded by helicopter to the requesting agencyor to the photo lab for development and interpretation by thephotographic and / or imageryinterpreter team.

What does the future holdfor the drone? The future willprobably be the era for thespace platform. Eventually aspace platform will be developed for inter - earth - spaceglobal surveillance and a newerversion of our current dronewill perform lower altitude continental surveillance. The missions of these vehicles will bedetermined by the sensoryequipment aboard and their re-lated capabilities.We logically ask, how othese vehicles fit into our overall military weapons inventoryof the future? The most likelyarea is the strategic and combat intel ligence field at all command levels.

In the strategic intelligencefield (we can say generally), a

nation s productive capacityand relative strength is dependent on its capabilities in fivecategories: raw materials, processing and end products manu-factured, supporting services,production of basic service, andimports and exports.In the combat intelligencefield we can say that a nation smilitary strength lies in itsmilitary forces and their re-lated locations and defenses.Other factors that must beknown in this area are theweather and terrain.Each of these areas then havepotential targets and sources ofinformation which our vehiclesof the future will seek. Usingexisting maps, surveillance systems will obtain informationrelating to where, when, andhow hard a target will be at -tacked. Provided with this information our military forcescan send appropriate destruc-tive fires into discovered tar-gets by either missiles or man-ned aircraft. D


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ew ccidentReporting Form

epared by the United States rmy Board forviation ccident Research

N W THAT DA FORMS 2397 through 2397-10, Technical Report of U. S. Army Aircraft Accident - Part I, and Flight Surgeon sTechnical Report of U. S. Army Aircraft Accident - Part II, have been published and issuedto the field, questions concerning these reportswill inevitably arise. Here, in brief, are theanswers to some anticipated questions.Why a new reporting form? Aircraft accident prevention depends to a large extent onresearch of past accident experience. This research is completely dependent upon the information contained in aircraft accident reports. DA Form 285, while adequate for reporting many types of accidents, does not allowfor the complexities of today s aviation andaircraft. In the past, many aircraft accidentreports contained all available information.Others left much to be desired. The new re-porting forms are designed to standardize andobtain the maximum information from eachaircraft accident investigation.

Will the new form increase the workloadon aircraft accident investigation boards?Only t the extent it may require more information than you have been used to submittingwith accident reports. Actually, the formsshould simplify the work of aircraft accidentinvestigation boards by serving as a checklistfor gathering all required information.Is DA Form 285 no longer required for reporting aircraft accidents? The new reportingforms will serve as additions to, and not replacements of, DA Form 285. DA Form 285will continue to be required for reporting Armyaircraft accidents (paragraph 23, AR 385-40).What regulation covers the new reportingforms? Newly revised effective 1 July 1961)AR 385-40 includes requirements for the newform. These requirements may be found inparagraph 3l.Where will I find instructions for completing the new forms? The new forms are issuedin pads of individual pages, DA Form 2397through DA Form 2397-10. Instructions for

25


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SEPTEMBER 1961completing Part I (Technical Report of U. S.Army Aircraft Accident) will be found as thetop sheet on the pad containing DA Form 2397.Instructions for completing Part II (FlightSurgeon's Technical Report of U. S. Army Aircraft Accident) will be found as the top sheetof the pad containing DA Form 2397-6.

When is the new form required? The DAForm 2397 series will be required for all majorArmy aircraft accidents. It will be submittedfor minor accidents only when injuries or psychological or physiological cause factors areinvolved. In addition, Annexes A-E, DA Forms2397 -6 through -10 will be submitted for forcedlandings and incidents, in which inj uries aresustained, or in which there are physiologicalor psychological cause factors.

Will the 2397 series eliminate the need foraircraft accident report attachments? No. At-tachments to DA Form 2397 will include:

for preceding 6 months).5 Certificate of damage to the aircraft.6 Copy of DD Form 78-1 or DA Form 2391-1 (Aircraft Flight Report and MaintenanceRecord).7. DD Form 781-2 and 3 or DA Forms 2391-2 and 3 (Aircraft Flight Report and Mainte

nance Record).8. Flight Surgeon's Technical Report ofU. S. Army Aircraft Accident (Annexes A-E,DA Forms 2397-6 through -10).9 Witness statements.10. Weather Report.11. Copy of any directives, regulations, etc.,that may be appropriate.12. Diagrams and photographs.13. Any other information deemed pertinentby the accident investigation board.The average cost of an Army aircraft ac

cident will continue to increase as new andmore expensive aircraft are added to the in-1. Copy of orders appointing aircraft acci- ventory. Prevention of future accidents willdent investigation board. depend in large part on the knowledge we gain2. Copy of crash facts message. from past accident experience. The new DA3. Continuation sheets when necessary. Form 2397 series will help to supply this

4 Individual flight record (DA Forms 759 knowledge.~ ~ ~ t was holiday routine for the USS BENNINGTON (CVS-20) deployed in mt

~ ~ ~ WestPac. The pilots of VS-38 in readyroom 2 were chewing the fat and ~ f illl ll telling sea stories. With a little time, a dictionary and a pocket thesaurus l tM this is what VS-38 made of the safety officer s slogan of the week, Proper nIpreflight procedures preserve pilots' posteriors.IA Pilot s p r ; ~ ~ ~ f ; ~ h t II arable p r = ~ ~ ~ ~ t l Y IIof P s p e ; ~ = ~ ~ Im prevent t

26

Reprinted omApPROACH, y 96

pUlsatingpalpitations,paralyzingly

prolongedparanoia;positivelypreserveparticipatingprofessionalpilots'perpetually

pamperedposteriorsperfectlyD. C. CURRAN


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S YED y Ground EffectHERE WE SAT on solid ground in whatwould have been a crashed aircraft had

it not been for ground effect. Good old groundeffect.The colonel turned to me and said, Youknow, Captain, I never cease to be amazed atwhat these helicopters can do.Sir, I never cease to be amazed at themeither. The perspiration that had popped out

on my brow during the last 10 seconds beforetouchdown was beginning t run. As I wipedit off, my handkerchief smothered a sigh ofrelief.He shot me a puzzled glance. I wonderedif he also felt this relief or if he thought myanswer a little out of line and figured that Ishouldn't be amazed, considering my rotarywing time.After the colonel had thanked me for theride and started toward the division head-quarters, I realized the irony of the whole sit-uation. The colonel did not know that we hadbeen in serious trouble and had been savedfrom a crash by the phenomenon known asground effect.Ground effect, however, is only a happycoincidence which prompts me to relate thisexperience. The point worth passing on is thatas a pilot you can't epen on ground effect oranything else to take care of carelessness. Iwas lucky in this case, but neither you nor Imight be as lucky the next time.Let me tell you how it happened. Just be-fore picking up the colonel, I had dropped theOld Man off at headquarters and had re-moved the metal star plate from the bracketand put it under my seat as I always did.

TROUBLE REWINGI knew from past experience that move-ment of the pilot's seat cushion and the heli-

copter would cause the plate to move around.This had been all right in the past, but on theflight with the colonel the plate worked partial-ly out from under my seat and lodged betweenit and the colonel's seat. One end of the platerested firmly against the head of a loose screwand the other end on the collective pitch dualcontrol lever. As the control was moved slight-ly during normal flight, the end of the plate

rode up and down the lever with no effect onthe control.When letting down at headquarters, Istarted pulling in the collective pitch in theusual manner about 75 feet from the ground.The plate slid up the dual collective pitch lever

until it struck the handgrip and wouldn't per-mit the lever to move any higher. I eased offon collective a little and pulled again. Thelever, of course, stopped at the same place. Theplate was made of strong aluminum, because Iwas really pulling and having no effect. At thetime, I did not realize what was happening.We were less than 75 feet up with a 300 fpmrate of descent and a jammed collective pitchlever. I immediately cranked in throttle, think-ing that at least I would have high rpm whenwe crashed. Rotor speed was building up andwe were headed for the ground with whatlooked like no way out.Suddenly, when we were only a few feetfrom the ground, the rate of descent slowednoticeably and we touched the ground in oneof the lightest touchdowns I have ever experi-enced. I backed off on the throttle, and that iswhen the colonel remarked that he never ceasedto be amazed at what these helicopters can do.He just didn't know how close we had come toa crash. I did and, needless to say, I don't placethe Old Man's metal star plate under my seatanymore.

GROU N D EFFECTA word about this phenomenon, ground ef-fect. You may be thinking that the increase inrpm was the thing that checked our descent.

This helped some, but when your rpm is al-ready at normal operating range, it takes moretime than we had for any appreciable gain. Atthe most, the increase was not over an addi-tional 100 and would not have stopped the de-scent. Undoubtedly it was ground effect thatsaved us.What is ground effect and how does it affectaircraft performance? In a rotary wing air-craft ground effect is commonly referred to asground cushion and has long been recognizedby pilots as a very significant factor in heli-copter performance. t results from the effectof the ground on the downwash of air from the

7


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SEPTEMBER 1961rotar blades during flights close to the ground.Several factors influence the amount of additional lift obtained from the ground cushion,but the two most important are speed of flightand height above the ground. The greatestamount of lift is received during slower flightnear the ground. At a speed under 15 knotswith less than 30 feet elevation, lift for a givenpower setting can be increased as much as 35percent.Consider the difference 35 percent additionallift can make when flying with a heavy load orduring critical flight conditions, such as athigh altitude or during a hot day. With eitherof these conditions, gaining maximum benefitfrom ground effect can actually mean the difference between being able to take off and notbeing able to take off.

OW T US ITHere is the way ground effect can be usedto best advantage. Hover the aircraft within afew inches of the ground and avoid suddenmovements of the controls. If possible selecta takeoff flight path over smooth, firm terrain.Hover forward slowly and allow your speed tobuild up very gradually. Stay close to theground until your speed is about 35 knots andthen start a gentle climb. If this procedure is

not followed with a heavily loaded helicopteror during critical flight conditions, the helicopter will settle to the ground. As it nearsthe ground additional lift will be obtained andit will tend to bob up and down, rising with theaid of ground effect and settling when it getsabove the effective height of the ground cushion. Ground effect must be used until airspeedsufficient to afford the lift required has beenobtained.To take advantage of ground effect ontouchdown, plan your landing so that the aboveprocedure will be reversed. Keep good air-speed until you are at low altitude and thenestablish a slow rate of descent until theground cushion checks your descent. With thisprocedure you can make an easy landing, evenwhen your load is too heavy to hold at a hover.The benefits to be gained by using groundeffect to advantage are important. Not knowing about these benefits, or not using them, canresult in an accident. Don t let it happen toyou. 0

Ground effect may not always give the expected ordesired results and sole reliance cannot be placed uponit. Running landings and takeoffs utilizing the effect,but not solely predicated upon it, are safe and desir-able techniques recommended by the Department ofRotary Wing Training, USAAVNS. - EDITOR

High Performance Helicopter Design Study onductedDESIGN STUDY of a high performancehelicopter capable of carrying a payload of2 tons at a top speed of 181 kt and cruisingspeeds up to 174.1 kt has been conducted bySikorsky. t is based largely on the dynamiccomponents of the HSS-2 helicopter SikorskyS-61) which recently set a world record formaximum speed without payl

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Army Aviation Digest - Sep 1961

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