8/13/2019 Construction of a Snow Runway at Camp Century for Wheel Landings with Lightweight Aircraft

1/9

00

oQ

CRREL S 6AUGUST1964

SpecialReport62k Constructionofa SnowRunwayatCampCenturyfor

WheelLandingswithLightweightAircraftbyGunarsAbele

O P Y ~?~ GF 2H H DO P Y .,*

8/13/2019 Construction of a Snow Runway at Camp Century for Wheel Landings with Lightweight Aircraft

2/9

8/13/2019 Construction of a Snow Runway at Camp Century for Wheel Landings with Lightweight Aircraft

3/9

8/13/2019 Construction of a Snow Runway at Camp Century for Wheel Landings with Lightweight Aircraft

4/9

CONSTRUCTIONOFASNOWRUNWAYATCAMPCENTURYFORWHEELLANDINGSWITHLIGHTWEIGHTAIRCRAFT

byGunarsAbele

RequiredsupportingcapacityofthesnowrunwayThespecificationsofatypicallightweightaircraft, theCaribou ,re:

Loadperwheel(maingear)Loadperwheel(nosegear)Tirecontactarea(maingear)Tirecontactarea(nosegear)Averagecontactpressure(maingear)Averagecontactpressure(nosegear)Therefore:

6, 10 8b0361b 174.5n.253.5in.235psi33psi

Atdesignloadsheaveragecontactpressuresareapproximatelyequaltoherecommendedtirenflationpressures.Inorderosupportwheeloadsproducingcontactpressuresbetween35to40psi,thefollowingramhardnessvaluesarerequiredforheop6in.ofthesnowpavement:

For:overage20 2coverages80 4coverages608coverages70 20coverages60(Eachcoverage ndicatesawheelloadpassagenthesametrack.)Theaboveramhardnessvaluesarereliableonlyif:

a)amhardnessforhe6to12in.epth 75%ofthesurface0to6in.)hardness;b)amhardnessforhe2to18n.epth-50%ofthesurfacehardness.TheminimumsurfaceramhardnessrequiredtosupporttheCaribou s20.Thishardnesscanbeobtainedbyrollingwithcorrugatedorsheepsfootrollersorcom-pactingwithLGP*tractors.

Itwouldbeunreasonableoassume,owever,hattheaircraftwillneverandinthesametracks. Afternumerousandings,heprobabilityofarepeatedlandingonanypreviouswheeltrackisncreased. Therefore,the-coveragecriterionmaynotberealistic. Itcanalsobeassumedthatcontactpressurehigherhan35to38psimaybeproducedbyimpactduringaanding. A200o30 0ramhardnessrangeshould,therefore,econsideredasheminimumrequired.Introducingareasonablesafetyfactor(approx.1.5),ramhardnessof30 0atanypointonthesurfaceoftherunwaywouldberequired.Inordertoobtainaconsistenthardnessofthismagnitudeoverheentireareaoftherunwayandtodecreasehepossibilityofdangeroussoftspots,rocessingofthesurface(3to4ftdepth)becomesnecessary.

MethodofconstructinghesnowrunwayThepreferredocationoftherunwaywouldbeontheexistingrunwayatCampCentury.APeterplow,referably2plowswithbackcastingchutes,ouldbeusedforproc-essinga3-o4-ftthicksurfacesnowayer. RoughevelingwithanLGPtractorwith

*Lowgroundpressure

8/13/2019 Construction of a Snow Runway at Camp Century for Wheel Landings with Lightweight Aircraft

5/9

2ONSTRUCTIONOFASNOWRUNWAY WadeandsubsequentfineevelingwitheitherheGurriesRoadBuilder(ifavailable)orheGurriesSnowPlanerpresentlyatCampCentury)orbothwouldha-'etobeperformedimmediatelyafterprocessing(lesshan4hoursafterprocessing).

Approximatelyweekofagehardeningwouldberequiredbeforeherunwaycouldbeconsideredsafeforandingheaircraftonwheels.ThenaturalsurfacenowdensityatCampCenturyisapproximatelyone-halfofthedensityofPeter-plowprocessedsnow. Therefore, 4-ftdeepcutwouldgiveonlya2-ftthickprocessed-snowlayer. Itwouldbeverydesirableoprecompactthepro-posedrunwayareanorderoncreasehedensityofthenowlayerobeprocessed.Duringthewinterandearlyspringof1963,hisareacouldbecompactedwithLGPtractorsndrollersaftereachsignificantsnowfall. Bydoinghis,tmaybepossibletoobtaina3-ftprocessedsnowlayerandodecreaseheamountofdepressionoftherunwayinrespecttothesurroundingarea. Thiswoulddecreaseheubsequentmain-tenanceeffortrequiredforhecompactionofaccumulatednowontherunway.Itisrealisedthatanelevatedrunwaywouldbemoredesirable.However,heresultmaynotbeworththeconsiderableeffortinvolved. Anenormousamountofsnowwouldhaveobemoved. Sinceherunwayisorientednthedirectionofthe

prevailingwinds,heuseofsnowfencesornowaccumulationwouldbeoflittlehelp.TestingoftherunwayPeriodicramhardnessestsoftheprocessedsnowrunwayshouldbeperformedduringtheinitialagehardeningperiodaswellasduringtheuseoftherunway. Itmayalsobedesirableousehe5-tontruckatCampCenturyas estvehicleodetectanyoftareaswhichmayhavedevelopedontherunway.Theirstandingwithheaircrafthouldbemadeonskis.hentheplanehouldtaxionwheelsoverheentireengthoftherunway.ftherearenondicationsofunsafeconditions,ake-offsandlandingsonwheelsranfoLow.

EstimateoftherequiredeffortandtimeorrunwayconstructionThemostdesirableimeorherunwayconstructionwouldbeheirstweeksnJune.AtthisimeheGurriesRoadBuildermaybeavailable. Also,theweathercon-ditionsduringJuneareuchthatreasonableefficiencyandproductioncanbeexpected.Itisveryimportantthattheevelingoperationbeperformedwithinaewhornsaftertheprocesing. Frequentdelaysdueounfavorableweathermayseverelyhamperhepropersequenceofoperations,ndmpairhequalityofthecompletedrunwayas

whole.Assuminga5000x150trunwayanda o4ftdeepcut,heapproximateconstruc-tiontimerequiredcouldbeestimatedasollows:

Rateofcut 0t/min 600t/hrTimepercut5000t 60 0t/hr8.3 3hr 8.5hi/cutNumberofcuts 50t@8t/cut 18.75cuts 0cutsActualcuttime20cutsx8.5hr/cut 70hrMachineimecuttimex.5255hrAssumingatwo-shift,10hrsach,peration:

255hr@20hr/day 12.75days 13daysAssuming2plows;

Totalime6.5days.Assuming2ds/weeklostdueobadweather;Totalime8.5days2Peterplows).Usingasafetyfactorof1.5formaintenanceandminormechanicaldifficulties:

Totaltime13dayswithPeterplows).,

8/13/2019 Construction of a Snow Runway at Camp Century for Wheel Landings with Lightweight Aircraft

6/9

CONSTRUCTIONOFASNOWRUNWAYTherefore,therunwaycouldbeconstructedinweeks,singwoPeterplows,andtakingntoconsiderationdelaysdueoweather,maintenance,andminormechanicaldifficulties.AnLGPtractorwithbladewouldberequ.GurriesPlanerorRoadBuilder. 'dforroughlevelingandtowingofthe

MaintenanceoftherunwayBecauseofthesomewhatdepressednatureoftherunway,somenowaccumulation,primarilydueodrifting,canbeexpectedontherunwayduringhesummermonths.Sincehiswouldusuallybeamatterofafewinchesaccumulationatatime,compactionwithanLGPtractormaybesufficienttomaintainherequiredsurfacehardness.LevelingwiththeGurriesRoadBuilderorheSnowPlanermmediatelyaftercompactionwillprovideasmoothsurface. Itwouldbenecessaryhentoallowthisnewlycompactedandlevelednowlayeroagehardenateast48hours.Ramhardnessestsandraffictestswithhe5-tontruckwillndicatewhetherornotawheeledaircraftandingwouldbesafe.Compactionofaewinchesofsnowaccumulationontopofthehard,rocessed

snowpavementwouldbeessime-consuminghanremovalofthenow.Moremportant,theelevationoftherunwaywouldbemaircainedataevelcomparableohatofthesur-roundingarea.Also,yattemptingoremove ewinchesofsnow,heoriginal.surfaceofth erunwaymaybedamaged.Removalofanewnowaccumulationisnotrecommendedatanytime. Thiswouldonlycreatemoreproblemsater.Afteraheavynewnowaccumulation,8o2nches,forexample,tmaybedifficulttoattaintherequiredramhardness. Thisspossible,nevertheless,yrepeatedcompactioncoverageswithanLGP. Thisituationwillbeencounteredduringheearlyspringandlateallperiodswhenthenowaccumulationstheheaviest.Itisveryimportant,therefore,thatnewsncwaccumulationanddriftsbecompactedandleveledwhenevernecessary. periodiccompactingofnewnowcanbemaintainedthroughouttheyear,itmaybepossibleohaveherunwayoperationalonayear-round

basi.s. If,owever,snowsallowedtoaccumulateduringheeesactivewinterseasonwithoutperiodiccompaction,tmaybenecessarytoprocessheulldepthofthenewsnowduringhenextspring.CompactionwithLGPractorracksssuperiorocompactionbyanyothermeans.DuringJulyandAugust,emperaturesatCampCenturyoccasionallyreachorexceed32F,ndsofteningoftheopewinchesc'nowmaybecomedangerousorwheelandings. Sinceemperaturesnthisran usuallydonotastmorehanafewhours,reezingofthesoftsurfacewillfollowwithevenapossiblencreasenthesur-facehardness.Duringhesummerof1962,theemperatureroseo32Fonlytwice. Softeningoftherunwaysurfacecanoccurduringbright,sunnydays,eventhoughheairemperaturemaybebelow32F. Theresittlehatcanbedoneokeepherunwaysurfacehardduringhehoursofapparentmelting.Duringperiodsofwarmweather,itma

8/13/2019 Construction of a Snow Runway at Camp Century for Wheel Landings with Lightweight Aircraft

7/9

8/13/2019 Construction of a Snow Runway at Camp Century for Wheel Landings with Lightweight Aircraft

8/9

8/13/2019 Construction of a Snow Runway at Camp Century for Wheel Landings with Lightweight Aircraft

9/9

A2 PPENDIXA Therequiredramhardnessprofilestheminimumforsupportingtheindicatedwheeload,minimumsafecondition,ndrecommendeddesign)arehownonFigureAl,Becausehehighesthardnessnaprocessed,ompactedsnowpavementusuallyoccursatsomedepthbelowhesurface4or nches)nsteadofathesurface,thehapesofehecurveshownrepresentheypeofhardnessprofileshatwouldmostlikelybefoundnasnowpavement. Thedealprofilewould,fcourse,avehemaximumhardnessatth esurfaceofthepavement.

DEPTH (in) (cm)r0

20

20

30

40

60

i

commendedsafedesignondit ion

Minimumsafecondit ionfo rlandingandake off.

Minimumrequiredtosupportstationarywheelload/no tsafeforanding rake off.

100 2000 000RAMH A R D N E S S 500 600 700I J_ 5000 50 UNCONFINEDOMPRESSIVETRENGTHpsi)

FigureAl. Requiredramhardnessprofilesorupportingaircraftwheel'loadsf000bndroducingverageontactressurespo0psi.