Flight Deck Design Guidelines

8/6/2019 Flight Deck Design Guidelines

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DONALD J . VITALEFLIGHT DECK

DESIGN GUIDELINESTHEAUTHOR

i s the Naval Ship Engineering Center Representative to theNaval Air Systems Command fi r the F- I 8 and V/STOL Adesigns, and is also the Supportability Systems Engineer fi rLSD-41, LCAC, T-ARC. and JKSES designs. He graduatedfrom the Glenn L. Martin Institute of Technology. Universityof Maryland, in 1956, and subsequent thereto was a SystemAnalyst fir Naval Weapons and NASA Satellites at the JohnsHopkins University, Applied Physics Laboratory, and de-signed missile systems at the firmer Naval Ordnance Lab-oratory, White Oak, Md. From I969 until 1976 he specializedin Aircraji Camers as CVAN-71 Systems Engineer and CV-TCBL/CW-71 Aviation Integration Systems Engineer.

ABSTRACTAIrcd t c d e r flight deck dalgn b the m d t of a longiterative proarr which involver many complex and oftensubjective dccirio~. he proau b b u l d y a trial and erroreffort to integratemany diverse ~ C ~ I O Mnto an operationally~t f r f .C toqlight deck that b compatible with below decksarrangements. his paper attempts to deheate the rationalefor these dcdrlo~.Thore of llrcrrrft d e r daign related to thellrcrrrft/shlp Interf.ce M they apply to the flight deck u edescribed in detail. Ihb paper does not offer pat solutions toproblem of flight deck design, but reporb the operationalexperience g h e d with put Alrcrift c u r k r dealgan and dh-cumea problems which mwt be addreaeedin the daign of ne w

&craft curler flight decks.

INTRODUCTIONA I R , - CARRIERS RESULT =OM A MILITARYREQUIREMENT for a mobile, waterborne, tactical air-field capable of supporting sophisticated militaryaircraft in a hostile environment. The goal of the shipdesigner is integration of those functions necessary tosupport the military function into a comparativelycompact package which can safely perform the mission.If the same military requirement were met by using alandbased site, those functions which pose a hazard toeach other or which have little compatibility could bedispersed widely. The design problem is integration ofthese functions into the confines of a ship, whileallowing smooth operation during high stress levelperiods. Not only must those functions which havelimited compatibility function smoothly, but ideally nosingle function should pose a hazard to its neighborshould an incident or accident occur. On land oneprobably would not build an airport on top of a citywhich is on top of a munitions complex. At sea thedesigner is forced to do just this.

GENERAL ONSIDERATIONSAircraft carriers with different operational require-ments may have quite dissimilar numbers and arrange-ments of major subsystems. The aircraft complement isthe basis for determining many of the Flight and HangarDeck characteristics and is important in sizing most ofthe flight deck subsystems. Any specific mix of aircraftalso affects, directly and indirectly, many of thedecisions made during the design process. On the FlightDeck, such decisions may include consideration ofaircraft maintenance, refueling, traffic flow and park-ing for various operational situations, flexibility fordifferent aircraft mixes, and minimizing the restrictiveeffects of damage from heavy seas or wind.In arranging the Flight Deck, a constant series ofchecks and compromises with the requirements of thelower areas of the ship must be made. In many respectsthis is the most complex and subjective aspect of layingout a Flight Deck, often evolving into a seemingly endlessspiral of iterations. With each different ship, variousfactors will assume different relative levels of im-portance. The following is a brief discussion of some ofthese interactions that require consideration.The location and size of the hangar must be com-patible with the location of the aircraft elevators.The location of the after hangar bulkhead(s), in mostrecent carriers, has been determined by the size of thejet engine shop, aircraft structures shop, and relatedfunctions, which are located in the stem. The avionicsshops on the other hand require a more vibration freelocation and are therefore located forward.The forward hangar bulkhead is usually an extensionof the forwardmost (or next aft) main transverse bulk-head bounding the forwardmost magazine complex.This has been done to allow the lower stage weaponselevators to open directly into the hangar for strike-down to the magazines and to allow the Hangar Deckto be used as a transfer area during strikeup op-

erations. Weapons elevators should not interfere withaircraft operations or maintenance. If multi-stageelevators are used, transfer of ordnance between stagesshould be direct, close coupled, and unobstructed.The run of uptakes between the machinery box andthe Island requires care and compromise to minimizeduct length and turns and yet not interfere unduly withaccess on intervening decks. iFor nuclear powered ships, access for recoringmust be provided.Support must be provided for such heavy concen-trated loads as the Island, catapult troughs, catapultholdback structure, catapult water brake, jet blastdeflectors, and the integrated Catapult Control Station.Naval Engineers Journal, April 1978 13 7


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FLIGHT DECK DESIGN VITALE

For satisfactory operation, many of these subsystemsrequire precise alignment, and the design of theirstructural support systems requires special attention.Structural discontinuities, such as openings or breaksin the shell, lower decks, and bulkheads are implicit inthe location of many Flight Deck components such asaircraft and weapons elevators. The structural effects ofsuch openings, individually and in combination, mustbe assessed and compensation, either by increasedscantlings or relocation of the opening, provided.The Flight Deck configuration must be compatiblewith the ships self-defense weapons systems. There arealso interactions with ship functions such as line andanchor handling and replenishment at sea stations.The placement and number of aircraft elevators,weapons elevators, catapults, arresting gear, and othervital functions must be critically evaluated from thestandpoint of net ship vulnerability to the effects ofweapons attack.The foregoing is a sampling of the more important ofthe many interactions that influence the design of aFlight Deck.

AVIATION FEATURES ONSIDERATIONSTo understand the rationale for aircraft carrier designit is necessary to have some knowledge of the designrequirements from the viewpoint of both the engineerand the user. To accomplish this objective each aviationsubsystem will be described both functionally and inengineering terms. Operational constraints are dis-cussed where appropriate. Those subsystems andphysical constraints which dictate the character of theFlight Deck of an aircraft carrier are as follows:

Recovery Area.Launch Areab).Island Structures.Aircraft Elevators.Safe Parking Areas.Aircraft Services.Weapons Services.Self Defense Systems.Fire and Nuclear Biological Chemical (NBC) Protection.Accesses.Construction C onstraints.Seakeeping C onsiderations.

Recovery AreaAs the aircraft approaches the ship from the stem thepilot leaves the counter-clockwise approach pattern andaligns his aircraft with the stripes marking the recoveryarea. The aircraft at this time is in a dirty condition,i.e., flaps, gear, and hook down. Asspming an aircraftrequires 140knots approach airspeed and that a naturalsurface wind of 20 knots is blowing from bow to stern,plus a 20-knot ship speed, the relative velocity betweenship and aircraft is 100 knots or 169 feet per second.The aircraft is assisted to the touchdown point on thedeck by the Visual Landing Aid (VLA) System whichprovides the pilot with a visual reference for 3.5negative glide slope along the landing area centerline.

Perfect adherence to this angle provides an 11-footclearance between the aircraft tailhook and the ramp(round down) of the recovery area with touchdown 180feet forward of the ramp. In addition, the aircraft mayland 20 feet to port of the recovery centerline whileparallel to the recovery centerline, or may deviate amaximum of 7 to port from the recovery centerline ifthe aircraft tailhook engages the last (forwardmost)arresting wire.Theoretically the tailhook impacts just before, or aftof, in relation to the ship, the second or target arrestingwire (cross deck pendant) which it engages. Thetailhood unwinds the wire (Purchase Cable) from thearresting engine. The arresting engine is adjusted to apredetermined resistance for each aircraft type and itsgross landing weight.Each aircraft is either tailhook or arresting gearlimited for its maximum allowable landing (trap)weight, i.e., it has a maximum (hit) engagement speedwith the arresting wire based upon gross weight andlanding gear and tailhook limits. The arresting geartype and wire runout distance determine whether aparticular aircraft is arresting gear or tailhook limited.A major factor determining the arresting gear selectionis the ability of the ship to make its own Wind-Over-Deck on a still air day.When the aircraft is stopped on the deck, the arrest-ing wire is nearly fully extended. If the wire does notdrop clear of the tailhook on normal roll back after theaircraft is stopped, the arresting gear operator and/orthe hook runner will disenage the wire.When the arresting wire is clear of the tailhook, theaircraft is moved to an area outside the recovery area.For this maneuver, which involves aircraft turnaround,and for tailhook disengagement, an area forward of thearresting area is required.Should the aircraft miss all of the arresting wires(Bolter) or should the arresting equipment fail, oneof two things will occur. The pilot will accelerate theaircraft sufficiently to regain flying speed or the aircraftwill run over the forward end of the recovery area andcrash into the sea.An alternative landing method to the normalarresting wire landing is the barricade landing.Barricade landings are used only when the aircraft canneither make a normal landing nor be diverted to a landsite. The barricade, consisting of a net of nylon straps,is stretched between two stanchions in similar fashion toa tennis net. The stanchions are located farther towardthe bow than the hook touchdown point to give thepilot a greater opportunity to engage the barricade sincethe aircraft may not be capable of completing a normalarrestment or attempting a second pass. As the pilotflies the aircraft into the barricade, it wraps itselfaround the aircraft wings, detaches itself from thestanchions, and tension is applied to the arrestingengines cables. The cable retardation (run-out)setting is different from a normal tailhook arrestment asis the total deck runout. Aircraft disengagoment fromthe barricade is more time consuming than tailhookdisengagement. Therefore, barricade arrestment and

138 Naval Engineers Journal, April 1978


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VITALE FLIGHT DECK DESIGN

Figure 1. Typical Three-Wire Plus B u r l d e Syetem.disengagement combined with barricade rigging prior toengagement and rerigging after, represents a recoverydisruption. During barricade arrestment, Tankersmay be required for in-flight refueling of other airborneaircraft. Barricade arrestments require the aircraft to bealigned with and centered on the landing area center-line.

The turnaround distance and barricade stretchdistance must be adjacent and accessible to an areawhich provides personnel and aircraft safety after re-covery, i.e., a safe parking area.The first requirement for layout of a recovery area isarrangement of the arresting gear wires in relation toeach other and to the after ramp. As aircraft carrierpilots and equipments have evolved to the presentdegree of sophistication, the number of wires andbarricades has decreased. Todays Fleet Carriers haveeither three or four arresting engines plus a barricade

engine. Figure 1 shows a typical three wire plusbarricade system.The spacing between wires in a fore-aft direction hasbeen optimized at 40 k feet. This spacing minimizesboth hook bounce, which could result in a Bolter,and double wire engagements, which could damage the

aircraft. The greater the spacing the more likely thathook bounce will occur; the closer the wires, the morelikely that a double wire engagement will occur.The wire span (athwartships spacing between decksheaves) is a function of the dynamics of the system andis determined by the amount of arresting wirerunout, the minimum acceptable wire angle on thetailhook, and the load exerted on the wire by the air-craft velocity and weight. The span for a particular shipis determined by the dynamics of the aircraft which areexpected to be part of the Air Wing operating from thatship.Forward of the arresting wires, space must be allowedfor the aircraft to pull the arresting gear wire to itsmaximum payout distance (runout). The cross deckpendant is attached to a Purchase Cable on each side ofthe arresting area with clevis pin poured-socketconnectors. As the tailhook engages the cross deckpendant and starts to reel out the Purchase Cable, theconnection on each side is slammed to the deck. Impactpads must be provided on the deck to prevent damageto the connection. The distance between the deckpendant in its static position and maximum runoutcan vary from 250 feet to 350 feet, depending uponindividual aircraft requirements and the ability of theship to produce its own wind over the deck during zeroambient wind conditions. At maximum runout eitherthe turnaround criteria or the barricade stretch willdetermine the landing area length.Flight decks of Aircraft Carriers have been con-strained to a 126-ft clear limit line to port and starboardof the ship centerline for permanent structure becauseof drydock limitations. To accommodate the portdeviation landing (max. 7 from recovery area) a hingedextension beyond this limit is sometimes attached tothepermanent deck edge. This extension is not necessarilyhinged in the same sense that the wings of naval aircraftare, but it must be physically removable without cuttingsteel. Such installations are complex and costly, and areavoided if possible.

EARRICADE RUNOUTEU. A IRCRAFTPENDANT RUNOUTE Z I A I R CR A F T / /DECK EXTENSION

B A RR I CA D E R U N W TE2 A AIRCRAFT

ARRESTING GEARRUNOUT-3M) FTDECK SMEAVE TYPE-MK14

f NOSEWMEEL

143.m-

ROUND-DOWN ( R W I DECK WEAVE\ L

Figure 2. Arresting Geu, ype-MK14.Naval Engineers Journal, April 1978 139


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S H U T T L E T R A C K

1. SHUTTLE I N BATTERY POSIT ION2. AIRCRAF T AT T ACHE D T O S HUTT L E AN D HOL DBACK UN IT3. FORW ARD PRESSURE IS E X E RT E D ON T H E S HUT T L E FOR HOLDBACK TENSION ING

1. HOLDBACK U NIT RELEASES2. SHU TTLE TOWS AIRC RAF T FORWARD

\W A T ER B R A K EP IS T ON S A N D S H U T T L E H A L T E D B Y W A T E R B R A K E SSYSTEM

G R A B A D V A N C E S A N D L A TC H ES T O S H U T T L E

G R A B R E T R A C T S S H U T T L E TO B A T T E R Y P O S IT I ONFigure 3. Catapult Operation.

140 Naval Engineers Journal, Apri l 1978


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Figure 2 is an example of a typical recovery area.This example illustrates only the deck area require-ments for arrested and barricade recoveries. The angleof the forward ramp is important for aircraft beingrecovered normally and for Bolters, since the forwardsponson edge can produce an undesirable degree ofturbulence if improperly designed. For each shipdesign, turbulence must be minimized while adhering tothe other recovery area criteria. The stem ramp is per-pendicular to the recovery area centerline.A Bolter is an aborted arrestment. There are twoextremes, with an infinite number of conditions betweenthem, which may describe a Bolter. The safest typeoccurs when the tailhook misses all of the wires, theaircraft has not decelerated, and can become airborneagain before reaching the end of the recovery area. Themost dangerous Bolter occurs when engagementwith a deck pendant is made and for some reason (deckpendant failure, tailhook failure, et cetera) the aircraftis released after decelerating below flying speed. In thelatter case it is impractical to provide sufficient decklength for the aircraft to become airborne again. Thosecases which fall between the extremes require specialtreatment. This special treatment is provision of clear-ance forward of the landing area so that any aircraftwhich bolters and sinks (Bolter Sink) below theFlight Deck level will have a clear path at a negative

~~

holdback link. During the time the aircraft is beingattached to the catapult, the aircraft weight is verifiedby the pilot and catapult personnel. This data is relayedto the Catapult Control Station, while other Flight Decl

15 angle from the horizontal toward the water. Forangle deck ships, such as USS Nimitz, this means pro-viding a large enough angle between the recovery areacenterline and the ship centerline for the aircrafts star-board wing tip to clear the port forward Flight Deck edgeas the aircraft sinks below the Flight Deck level. Thisclearance isnecessary to prevent an aircraft, which canregain flying speed after sinking beyond the forwardlanding ramp, from hitting the ship and crashing ratherthan regaining flying speed and landing on a secondattempt.Launch Are a(s)

As the aircraft taxies to the catapult, the Jet BlastDeflector (JBD), which was raised for the previouslaunch, is lowered. As soon as the aircrafts tail clearsthe JBD, the JBD Operator raises the deflector panel.The Aircraft Director leads the aircraft to the stationzero position. The Catapult Crew attaches the nosewheel launch bar to the catapult shuttle and theholdback to the deck. Steam pressure is applied tothe shuttle at the battery position which tensions the

SEE NOTE 2

MK7 JBDMK 2 NGL

CATAPULT TROUG H-

59 IN.POWER STROKE,244 TO 304 FT,SEE NOTE 114 FT

WFT (MIN+ 4 TOTAL LENGTH. 273 TO333FT. SEE NOTE 1 n

14FT-WNOTES:1. OPTIMUM POWER STROKE (AND TOTAL LENGTH) DEPENDS UPON FINA L SELECTION OF AIRCRAFTTYPES AND VESSEL SPEED. DIFFE RENT POWER STROKES ARE REOUIRED AS A FUNCTI ON OF AIRC RAF TTYPES AND WI ND OVER DECK.LA

2. RECOMMEND 35 FT MINIMUM OF FL AT DECK FORWARD OF END OF POWER STROKE FOR AIC ROTATION.3. DISTANCE FROM BUTTRESS PLATE TO FORWARD EDGE OF FLIGHT DECK DEPENDS ONLY UPON A/CROTATI ON AS DESCRIBED IN NOTE 2 AND THE SHIPS STRUCTURE REOUIRED TOSUS TAIN CATAPULTBRAKING LOADS.4. ICCS LOCATION SHOWN I S FOR TWO BOW CATAPULTS.

Figure 4. Illustrative Example of hunch Syatem.Naval Engineers Journal, Aprll 1978 141


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personnel remove the red flagged safety pins, whichwould dud an inadvertent weapon release, from theaircrafts ordnance.After attachment to the catapult, the aircraft enginesare accelerated to the full military power setting and theaircraft strains against the holdback while the shuttlepulls forward on the nose wheel, Figure 3. The pilot andCatapult Officer agree that the aircraft is ready forlaunching and the launch signal is given. Steampressure on the shuttle is increased, which breaks theholdback link, and the shuttle, towing the aircraft bythe launch bar, accelerates to flying speed over thecatapult length in about 2 seconds. When the shuttlereaches the end of the power stroke, a water brake stopsit in 5 feet of forward travel. As the shuttle stops, itreleases the launch bar which allows the nose wheelstrut to extend from its compressed position thusrotating the aircraft from its nosedown launch attitudeto the predetermined take-off attitude peculiar toeach aircraft type.

The aircraft launching function is generally ac-complished using catapults to supplement the ability ofthe aircraft and the ship to provide sufficient windspeed relative to the aircraft for sustained flight. Foreach specific aircraft, a different minimum air speed isrequired depending on take-off weight, stores con-figuration, and ambient temperature. The catapultsystem must, therefore, be designed to accommodatethe worst case aircraft in its heaviest configuration. Thisthen determines the minimum length for the powerstroke of the catapult.Jet Blast Deflectors (JBDs) are located just aft of theaircraft launch position as shown in Figure 4. These aresea water-cooled deck panels which can be raised to asufficient angle to deflect upwards the exhaust gas of anaircraft being catapulted. These gases must be deflectedto:

1) Prevent compressor stall and/or flameout onthe engines of aircraft awaiting launch immediatelybehind the catapult.2) Prevent the exhaust gases from damaging theRadomes of aircraft awaiting launch immediatelybehind the catapult.3) Prevent ignition of explosives or rocket motorgrains on aircraft immediately behind the catapult byhot gas impingement.4) Protect Flight Deck personnel between aircraft inthe launch position and those awaiting launch.

The JBD is located sufficiently behind the catapult toaccommodate the worst case aircraft expected to belaunched, as regards exhaust gas temperature, direc-tion, quantity, and the worst case aircraft to beprotected behind the JBD.Sea water-cooled Deck Cooling Panels are locatedforward of the JBDs to cool the deck areas heated bythe deflected jet engine gases. These Cooling Panelsprovide reasonable deck temperatures for subsequentaircraft/catapult hook-up and aircraft weapon arming.

The catapult and its associated systems have thefollowing location constraints which should be appliedas stringently as possible:1) The catapult longitudinal centerline must lieinboard of the flight deck side sufficiently to preclude a

main gear wheel dropping off the deck edge duringlaunch. Two feet is nominal wheel to deck edgeclearance.2) The catapult longitudinal axis should be as close tobeing parallel with the ships longitudinal centerline aspossible. A maximum deviation of 6 is allowed.3) Jet Blast Deflectors, where possible, are kept outof the landing area to preclude a fouled deck caused byfailure in the UP position. Where it is necessary to havecatapults in the landing area, as in the case of the fourcatapult ship, the JBD erection system should have aquick-release manual lowering system.4) When catapults must be installed in the landingarea, the arresting wire/catapult trough interface mustbe designed to preclude catching the arresting wire inthe catapult trough at full runout, thereby damagingthe wire.5) The forward edge of the Flight Deck must be farenough forward of the launching system to provide thenecessary aircraft rotation distance, or to providesufficient depth for the retardation structure to absorbthe load transmitted from the water brake, whichever isgreater.Island

The Island contains a variety of services which 8terelated to the Flight Deck and which are required to belocated at or above the Flight Deck level.For a fossil fueled ship, the Island contains theintakes and the uptakes for the propulsion system andits location must, therefore, take into consideration therouting of these ducts. An alternative is the side pipesused by Japan during World War I1 which were loweredbelow Flight Deck level during aircraft operations.The Island location, size, and shape can affectaircraft during recovery. The stacks for a fossil fueledship are a potential source of smoke which can partiallyobliterate the pilots view as he lands. The aero-dynamics of the Island determine the severity of theturbulence through which an aircraft must fl y durhgrecovery. The flow around the island and the flow ofexhaust gases are investigated by model test during

design.The Islands existence makes it a prime platform forelectronic emitters, and as many as possible of theships antennas are installed on it. Island real estate hasbecome so saturated with antennas that more recentAircraft Carriers have required the addition of a toweron the Flight Deck to accommodate all of the emitters.The panoramic view from high on the Island is idealfor the Pilot House (Ships Bridge) and the Flag Bridge.Visibility from the Pilot House must be such that theCommanding Officer can conn the ship, oversee flightoperations, and conduct underway replenishment withease.142 Naval Engineers Journal, April 1978


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VITALE FLIGH T DECK DESIGNPrimary Flight Control (Prifly) must be located onthe Island above the Flight Deck in a manner whichenables the Air Officer and his assistants to controlflight operations. A panoramic view of the whole FlightDeck is desirable to enable Prifly to coordinatelaunch, recovery and movement of aircraft safely.Flight Deck Control is normally located on the FlightDeck level within the Island to enable the Flight DeckOfficer to control flight deck traffic and be readilyaccessible to the Aircraft Handling Officer.The Aviation Maintenance Center is also normallylocated in the Island on the Flight Deck so as to beaccessible to S quad ron maintenance personnel.The base of the Island also serves as an air terminalfor passengers, mail, and freight because of its con-venient location.To perform most of its aircraft-related functions theIsland should, ideally, be centrally located on the FlightDeck. Since this would interfere with a ir operations theIsland has traditionally been located adjacent to the

starboard Flight Deck edge near midship.Aircrafr Elevators

Aircraft elevators are required to cycle aircraftbetween the Flight Deck and the Hangar Deck. Supple-mentary tasks include moving aviation ordnance to theFlight Deck and striking 8own Vertical Replenish-ment (VER TREP ) S tores and ordnance to the MainDeck. During air operations, aircraft ready for flight arecycled up, while those requiring maintenance arecycled down.Elevators on early Carriers were located within theshell of the ship. This design protected the aircraftfairly well from spray. However, the following disad-vantages pointed the way to deck edge aircraftelevators:

Increases in aircraft size require total ripout andmajor structural modification to install a largerelevator.When the elevator is down, the re is a large openingin the center of the Flight Deck, unless, as in the F renchAircraft Carrier Beam (1922-19681, Flight Deck closuresare provided.When the elevator is raised, there is an opening inthe Hangar Deck unless an elevator pit platform isinstalled.The elevator trunk requires a large piece of primereal estate in the cen ter of the Gallery Deck.In a carrier with a ballistic Flight Deck, the han garis unprotected except when the elevator is full up.The hangar can become a large pit filled withexplosive gases as it did in th e USS Princeton (CVL-23)during World War 11. Princetons aircraft elevatorswere blown ajar by the explosion of gasoline vapor inthe hangar.Flaming debris or other hazardous material cannot be conveniently and as rapidly jettisoned over theside from the hangar unless a separate large access isprovided.

Adequate operating and handling area for replen-ishment-at-sea is much more difficult to ob tain.In po rt, cran ing of aircraft from the dock wouldhave to be to the Flight Deck rather th an to the H angarDeck.Fuel spillage into the elevator trunk can producehazardous conditions within t he ship.

Flight Decks with deck edge aircraft elevators and noinboard aircraft elevators were first incorporated in thedesign of the USS United States (CVB-58) which wasnot constructed (keel laid 18 April 1949- onstructionhalted 2 3 April 1949). US S Forrestal, commissioned 1October 1955, was the first American Carrier t o be con-structed with deck edge elevators only. Advantageswhich may be cited for deck edge elevators are:Ability to accommodate larger aircraft (tails maybe hung over the side as long as main landing gear andnose fit on platform).In both Flight and Hangar Deck positions theelevator platform is adjacent to, rather than in, thecenter of traffic patterns.Main Deck is more accessible for replenishment-at-sea. Hangar Deck can be ventilated more easily.Hazardous material can be quickly jettisoned fromthe hangar.Aircraft and ships boats can be craned from thedock to the Hangar Deck.Jet aircraft can be delivered to main (han gar) deckwith engines on and hot taxied into the hangar.Damage to an elevator not in full up position willnot normally foul the Flight Deck.Platform location is more easily moved if requiredas in the case of Ship Alterations (SHIPALTS)developed to accomm odate JBDs for the F-14A.

Disadvantages which may be cited for deck edgeaircraft elevators are:Sea spray impingement on aircraft hastens cor-rosion.Green water on platform in the lowered position isa danger to aircraft and personnel.Elevator platforms have been lifted by wave actionand allowed to slam.Limited freeboard of smaller ships makes platformmore susceptible t o wave damage.To provide adequate freeboard for aircraft ele-vators the ship may have to be m ade deeper with a con-comitant increase in displacement, power, et cetera.Possibility of M ain D eck ( han gar) flooding duringhigh Sea States. For example, CVA-42 (F.D.R . ) took awave through the hangar doorway to her No. 1 aircraftelevator during 1974 which resulted in a floodedhangar, aircraft damaged by the hangar door, anddeath to a crewman caught between the sp rung doorand an aircraft.

Ideally, aircraft elevators would be supplied insufficient quantity and be so located that all phase$ ofNaval Engineers Journal, Apri l 1978 14 3


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VITALELIGHT DECK DESIGN

WING TIP 81PURCHASE CABLECLEARANCE AREAPORT SIDE PURCHASE

L A N D I N G $ n A R R E S T E D L A N D I N GI I a 9 9 9 E X TE N DE D P URCHAS E CABLE

I/ \S A F E P A R K I N G L I N E~~ ~

Figure 5. Safe Puking Line.air operations would be supported without delay.During recovery of aircraft at least one elevator shouldbe available to hot taxi an aircraft known to be indown status upon landing. During launching of aircraftsufficient elevator capacity must be available to cycleaircraft to the Flight Deck to support an Alpha Strike,i.e., all aircraft which are in an up condition arelaunched as rapidly as possible nd are cycled contin-uously for an all out effort. Between operationalcycles the elevators will be required to cyclerespotted aircraft between Flight and Hangar Decks.Each platform must be of sufficient size to safely handlethe largest aircraft expected on board. It should also beconfigured, if possible, to carry two or three smalleraircraft simultaneously. When carrying aircraft, theplatform and machinery should be capable of liftingaviation ordnance on Dollies in addition to the aircraftand their tractors. Consideration must also be given toelevator separation and the number of elevators toincrease the availability of elevators after battledamage.

A problem of considerable magnitude with deck edgeaircraft elevators is their exposure to sea spray and seawater. Ship freeboard and length mainly determine theproximity of the elevator to salt spray and green water.Sponson and elevator platform design determine theseriousness of the problem. Even on such a large ship asthe Nimitz there is sufficient likelihood of a problemnrcumng, and so the elevator mzchinery was designedto remove slack from the cable automatically should awave lift the platform.Safe Parking Areas

Safe parking is usually defined as the Flight Deck areaclear of the landing area; this includes space on boththe port and starboard side of the landing lane.For design purposes safe parking is defined as thatarea at least 50 feet to starboard of the landing areacenterline in which no contact can occur between theaircraft being recovered, the barricade, the cross deckpendant or the Purchase Cable and aircraft, yellow

Figure 6. Theoretied Safe Pukiog Requirement.144 Naval Engineers Journal, April 1978


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gear, or personnel starboard of the landing area. Thesafe parking line is drawn 50 feet to starboard of thelanding centerline from the forward ramp aft towardthe arresting area, then slightly more to starboard toskirt the arresting gear sheaves and return to the !%-footwidth aft of the sheaves (See Figure 5). Figure 6 is anexample of safe parking requirements on an arbitrarybut practical basis. The starboard safe parking line islocated such that there is a clear deck 50 feet tostarboard of the landing centerline between the afterramp and P1. From P1 to the barricade stanchion theline should be starboard of the deck sheaves. From thestanchion forward it must clear the barricade PurchaseCable and aircraft wing tip path. For the port side, thesame criteria applies except that the requirement forarrested landing wing-tip clearance is greater than thestarboard clearance. This is due to allowance for eitheran axial landing (in relation to the recovery area center-line) 20 feet to port of the recovery area centerline, or alanding with the aircraft yawed 7' to port of therecovery area centerline with touchdown on the recoveryarea centerline.Aircruj? Services

Aircraft services include: Electrical, Fuel, StartingAir, Air Conditioning, Oxygen (liquid and gaseous),Nitrogen, and Inertial Navigation System Alignment.Of these, all except oxygen (both liquid and gaseous)because of the safety problem, may be built into serviceoutlets in the deck. Liquid and gaseous oxygen are dis-tributed to the aircraft by mobile carts. Therefore, onlyone O,/N, Filling Station is required, and this stationshould be conveniently located adjacent to the hangararea.To determine the location of the various aircraftservices, spotting studies are conducted for all notionalairwings, flight deck configurations, and variations inoperational modes to determine the optimum number ofservice outlets and their locations.Weapons Services

Weapons Services consist of the weapons elevators,Dollies, hoists, and miscellaneous gear necessary forarming the aircraft. All of these are mobile except forthe weapons elevators which should be kept out of thelanding area entirely and out of traffic patterns as muchas possible. The weapons elevators, with their ballistichatches opening above the deck, present a Flight Decktraffic problem. The design and location of weaponselevators should minimize the possibility of precipita-tion and fuel spills draining into the elevator shafts.Inboard elevators should be placed just inboard oroutboard of the hangar side bulkhead. For two stageelevators with transfer on the Hangar Deck level, theoutboard position has the advantage of not interferingwith hangar functions.Deck edge weapons elevators, as on MIDWAY Classships, have the advantages of being outside the FlightDeck traffic flow and do not interfere with hangar

functions, but they are subject to the same salt waterproble,ms as the deck edge aircraft elevators unless en-closed within the sponson. There are several advantagesfor outboard weapons elevators which should be con-sidered. They are:Increased ship safety and decreased ship vulner-ability.No interference with aircraft movement.Increased "strikeup" rates.

e Use less valuable Flight Deck real estate.Could also provide elevator service in sponson areasto vital aircraft/weapon support equipments lo-cated between the Hangar and Flight Decks,thereby freeing Hangar/Flight Decks of this typegear.Self-Defense Systems

Self-DefenseSystems affect Flight Deck design by theextent of protection required, weapon requirements,and the threat to be defeated. The arcs of fire of theSelf-Defense Systems are generally specified as pro-viding 360' hemispherical coverage. Commencing withthe CVA-59 design, all Self-Defense Systems, with theexception of gun/missile directors, have been installedbelow the Flight Deck level. To provide 360" surfacecoverage, four systems, one in each quadrant, arerequired. Each system has been installed on a weaponssponson. To provide hemispherical coverage the weaponsponson must be located in relation to the Flight Deck sothat the weapon has at least 90" azimuth coverage plussufficient elevation to cover targets directly overhead toslightly below the horizon, including an allowance forroll and pitch.To allow for maximum possible quadrant coverage,these weapon sponsons have generally been located atthe forward and after ends of the Flight Deck sponsons.There have been seakeeping problems with the forwardweapon sponsons due to their proximity to the bow.The after weapons sponsons do not generally sufferbad weather damage due to their protected location aftand inboard of the Flight Deck sponsons. However, therequirements of the after weapons sponsons dictatesomewhat the shape of the Flight Deck in this area.Eliminating the forward weapons and supportingsponsons makes the design of the after weaponsponsons and the adjacent Flight Deck area moredifficult since the after weapons must now provide asmuch forward fire as possible.The Naval Air Systems Command requires clearanceabove a negative 15" angle drawn outboard and per-pendicular to the Flight Deck edge to prevent aircraftcontact with ship subsystems, for example, whipantennas.Fire and NBC Protection

All Flight Decks must be provided with a deck edgeplus inboard sprinkler system capable of covering theentire deck for both fire protection and NBC (Nuclear,Biological, Chemical) washdown. Facilities for fire hosesNaval Engineers Journal, April 1978 145


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VITALELIGHT DECK DESIGN

must also be provided for total Flight Deck coverage,including overlap. Weapon jettisoning ramps must beprovided to enable personnel to remove hot weaponsfrom the Flight Deck without striking any part of theship on the way to the sea.Accesses

Access to the Flight Deck is required by large numbersof personnel for many reasons and for a variety of tasks.Catapult associated personnel include the CatapultOfficer, Deck Edge Station Operator and all those asso-ciated with attaching the aircraft to the catapult,removing the weapon safety pins, checking aircraftlaunch weight, et cetera. These personnel must haveimmediate and unimpeded access from the Gallery Deckto the catapult areas via Gallery Deck catwalks.Arresting gear personnel include the LSO (LandingSignal Officer), his assistant, the Arresting Gear DeckEdge Station Operators, the Hookman, and the AircraftDirectors. Their access requirements are similar tothose of the catapult personnel except that in an emer-gency, a ramp strike for example, the LSO and theStation Operators will require escape chutes to a havenbelow the Flight Deck.The Flight Deck Officer and his team require un-impeded access to the Flight Deck from Flight DeckControl in the Island structure.Squadron maintenance personnel are generally lo-cated in Gallery Deck compartments outboard of thesheer strake and require access to recovered aircraft viaGallery Deck catwalks. Access must be provided whichallows safe transport of tools and personnel.Aircraft fueling teams must have access between theGallery Deck and Flight Deck adjacent to their fuelingstations.Weapons elevator operators and handling personnelare not allowed to ride the weapons elevators and must,therefore, have access to the Flight Deck via catwalks.Missile wing and fin stowages must be located nearaircraft parking areas and have direct access to thestarboard Gallery Deck catwalk and the Flight Deck.Inboard stowages are not acceptable due to the weight,size, and fragile nature of these aerodynamic surfaceswhich might be damaged by passage through hatchwaysand doors. Parachute flare ready service lockers, alsolocated at the Gallery Deck edge, must have clear dropzones to the water in the event jettisoning is required.Aircrew Ready Rooms are usually distributed on theGallery Deck. Aircrews usually are provided with ReadyRooms sufficiently forward or aft to allow direct accessto the catwalks from the main fore and aft passageways.FLIGHTDECK ESIGN

Flight Deck Design is the integration of the functionspreviously described. However, before the Flight Deckcomponents Can be arranged as a functional system,other factors related to both ship and aviationfunctions must be considered. These include:Approximate Hull Length.

Approximate Beam.Approximate Hull Shape.Machinery Plant Candidate($.Armor Box Volume and Height.Number of Shafts.Approximate Hangar Area and Height.Freeboard to Main and Flight Decks.Prior to laying out the Flight Deck, an inboardprofile of the ship locating the machinery plant, avia-tion ordnance magazines, and the aircraft hangar asdedicated blocks of space is developed. .-

Inboard PmjileSome possible configurations of the magazine-machinery complex are shown in Figure 7.Hangar Deckarrangement is the result of many compromises tooptimize as much as possible each of its operationalrequirements. The Flight. Deck dictates location of theupper stage weapons elevator along or outboard of thestarboard hangar side bulkhead. Weapon elevatorhatches should not be within the landing area on theFlight Deck. The lower stage elevator locations aredictated by magazine constraints. Weapons elevatorlocations in a hangar bay as illustrated by Figure 8represent an acceptable compromise from the aircraft

MACHINERY MAGAZINE

MAG MACH MAG

MACH MAG MACH MAG

MACH MAG

MACH MAGAZINE MACH

MAG MACH MAG MACH MAG

Figure 7. M.Ehinery/M@e Amqgements.146 Naval Engineers Journal, April 1978


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....................FW O+ s HIP%

SOLID L I N E S A I R C R A F T I A R K I N G P A T T I H N Lm q I H C R P L I P A R K I N GB R O K E N LlN fS S T R I K E D O W N T R A F F I C P a l l t R N SD O T l E D L I N f S S T H I K E U P l R A F Fl C P I T T I R N S

Figure 8. Example of J l q p r Bay Arrangement.handling, aircraft parking, and weapons strikeup/strikedown point of view.Integration of Launch and Recovery Area

Of primary concern is the relationship of the aircraftrecovery and launching areas. Previously the functionaland physical relationship were examined as separateentities, now the two must be combined. The latestcriteria for Aircraft Carriers are that a recoveryBolter will not pass through the recovery parkingarea and the aircraft recovery and launch may occursimultaneously. Thus, the recovery and launch blocksfit together as illustrated by Figure 9. It is obvious thatchanges in the launch recovery interface requirementswill change the size and shape of the blocks as well astheir angular relationship. Alpha is limited to amaximum value of 12.These are several factors which may constrain theminimum value of Alpha. These factors are:

Bolter (previously described).Simultaneous Launch and Recovery: Alpha mustbe sufficiently large to allow the largest aircraft to beattached to a catapult while standing clear of therecovery area safe parking line.Safe Parking: Provision is usually made tostarboard of the recovery area for safe parking, i.e.,away from Bolters. This may be accomplished byangling the recovery area or by offsetting to port anaxial recovery area.

The requirements for launch and recovery must bereconciled with each other and with the postulated hullbefore the remaining functions are considered. Therecovery area has a minimum length and widthdetermined by the postulated Air Wing and ship speed.The length of the recovery area may be increased shouldship length permit it. A rule of thumb is that theforward recovery ramp should be about 30% of LBPback from the forward edge of the Flight Deck in orderto preclude damage to the sponson from wave action ina high sea state.

A second rule of thumb is that the after end of theFlight Deck sponsons will terminate no further aft than15% of LBP from the AP. This rule of thumb is asso-ciated with a requirement to avoid damage during highSea State condition. However, there are no knowninstances of Aircraft Carriers receiving either FlightDeck or weapon sponson damage in this area, nor isthere any evidence of transom damage due to followingseas.The starboard sponsons support the Island and amajority of the aircraft elevators. The extent and loca-tion of the starboard sponson is also dictated by aircraftelevator locations in relation to the hangar bays and byalignment of replenishment stations with the replenish-ment stations of the various Auxiliary Ships.The Island must be located on a starboard sponsonamong the aircraft elevators, and provide for a suitablerun of uptakes and ventilation ducts for the machineryspaces for a fossil fuel powered ship. Idealized place-ment of the Island and the aircraft elevators willprobably not be possible and a series of compromiseswill be made. In addition to the criteria for aircraft ele-vator locations which are driven by alignment with otherthan aircraft related functions and survivability require-ments, these aircraft Flight Deck constraints should alsobe applied:

An aircraft elevator should be immediately aft ofthe JBD Catapult No. 1 on the starboard side.An aircraft elevator should be to starboard of thefull runout point of the recovery area to allow hottaxiing of down aircraft onto the elevator and intothe hangar.At least one aircraft elevator should service eachhangar bay.There should be no blind access hangar bays, i.e.,each bay should be serviced by at least one aircraftelevator and have access to another bay through hangardivision doors, or be serviced by two aircraft elevators.A port side aircraft elevator provides grater missionsurvivability in addition to providing strikedowncapability for VERTREP of stores during alongsidereplenishment operations.These requirements would all be met in an ideal situa-tion, but the objective is to accomplish as many aspossible within each designs constraints. The primaryobjective is to provide unimpeded traffic flow to othercatapults and from the recovery area. Consideration

Figure 9. LauncbIRecovery Interface.Naval Engineers Journal, April 1978 147


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FLIGHTDECK DESIGN VITALEkigure 10. Typiul Flight k k .must also be given to delivery routes for aviationordnance as well as routes between the shops and theaircraft.Flight Deck Integration

Figure 10 illustrates a typical Flight Deck arrange-ment that conforms to the guidelines discussed pre-viously. Note that the after ramp of the recovery areahas been angled in alignment with the recovery area,and that the forward end of the port sponson has anextension to accommodate maximum offset recoveries.The bow catapults have been placed essentially parallelto each other. The waist catapults are placed outboardof the sheer strake to prevent penetration of the sheerstrake by the catapult troughs. No. 4 Catapult isparallel to, and as close to, the port deck edge as pos-sible, and is set back as far as possible to precludeinterference between its JBD and the port side bar-ricade stanchion while allowing No. 3 Catapult to haveits JBD forward and clear of aircraft on Station Zero ofNo. 4 Catapult. No. 3 Catapult is angled to port and isset forward on the port sponson to eliminate inter-ference, as much as possible, with aircraft at StationZero of No. 4 Catapult and to preclude slamming of thedeck pendant/Purchase Cable connection for P4 on theJBD aluminum panels.Number 1 aircraft elevator is just aft of the JBD forNumber 1 Catapult. Provision should be made forimmediate removal of an aircraft which goes down onlaunch to an area away from the launch area withoutinterfering with aircraft awaiting launch. The FlightDeck illustrated by Figure 10 provides this capability asfollows:

Catapult No. 1 and 2: Removal is to the starboardsponson and aircraft elevator No. 1.Catapult No. 3: Removal is to starboard adjacentor aft of the Island.Catapult No. 4: Removal is the same as forCatapult No. 3 except that Catapult No. 3 must becleared first.Number Three aircraft elevator is sufficiently forward tojust clear the safe parking line. Number Two elevatorand the Island are located to allow Number Twoelevator to service the center hangar bay and to allowthe intakes and uptakes easy access to the Island.Figure 10 represents the latest design in the evolu-tion of aircraft carrier Flight Deck arrangements, yet ithas the following limitations and undesirable features:

Closeness of the aft elevators and the arresting gearhampers arresting gear machinery arrangement.Arresting area size is restricted by proximity of theaft elevators.Port side extension at forward end of recovery areahampers maintenance operations in some port facilities.Proximity of Number One elevator and NumberOne catapult could hamper aircraft operations.These disadvantages might limit the development offuture aircraft since modification of the Flight Deckwould be precluded by the excessive cost.

CONCLUSIONSThis paper was written to examine the parameterswhich affect Aircraft Carrier design from the aviationpoint of view, and to document the rules-of-thumb,which have been and are being used, but not todelineate a specific methodology for design.Each ship design requires a new and different ap-proach to achieve a design solution even though thesolution may be evolutionary rather than revolutionary.

MARINE ENGINEERSNAVAL ARCHITECTS=@ YSTEMS ANALYSTSMARINE SURVEYORSGEORGE G. HARP, INCNEW YORK, N.Y.WASHINGTONl D.C.8

TOD D SHlPY AR DS COR POR ATI ON New York Brooklyn New Orleans Galveston Houston San FranciscoTOD D PAC1FI C SHIPYARDS CORPORATION Los Angeles Seattle

Executive offtces One State Street Plaza, Ne w York, N Y 10004 (212) 344-6900 Cable Robln New York7i j iBcToIODD148 Naval Englneers Journal, April 1978

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Flight Deck Design Guidelines

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