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UNCLASSIFIEDAD NUMBER

AD368426CLASSIFICATION CHANGES

TO: unclassifiedFROM: confidential

LIMITATION CHANGESTO:Approved for public release, distribution

unlimited

FROM:Distribution: Further dissemination onlyas directed by David Taylor Model Basin,Washington DC; Nov 1965 or higher DoDauthority.

AUTHORITYNov 1967, Group-4, DoDD 5200.10, 26 July1962; DWTNSRDC ltr 7 Oct 1980

THIS PAGE IS UNCLASSIFIED

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UNCLASSI FIED

d t

AN OPEN-OCEAN V/STOL SEAPLANE FOR THE ASW MISSION(Title Unclassified)

by

Richard D. Muirphy, Gary W. Brasseur,Robert Bart, and Robert M. Williams

This ~ ~ ~ eprounot210atofctnNovember Aero Report1096 *

l insC73 &d heFs 1 h

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UNCLASSIFIED

ForewordThis paper was init-ially presented at the AIAA/USN

Marine Systems and ASW Conference in San Diego, California,March 10, 1965. The results presented were derived from anindeperndenL ia-nous._ exploration of the potential of aV/STOL vehicle. Publication of the results does not implyendorsement by any organization other than the AerodynamicsLaboratory itself. The authors gratefully acknowledge the as-sistance of the following individuals for their contributionsin the maintenance of a realistic approach to operationalaspects: CAPT C. W. Griffing, ONR; Mr. F. W. S. Locke, Jr.,CDR R. K. Geiger, Mr. R. L. Parris, Mr. K. E. Dentel, andLCDR P. L. Dudley, Jr., BuWeps.

AcsoiFofe, NTIS CRA&I6 Ur IDTIC TAH

JuSthfhcjutc,ByDiStr ibution

Availbrlity Codes

V L'IUNCNC-LAS75SReFI2-UD

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ItJIflhElW'UNCLA3S ,FED,N CSYMBOLS

b wing span in feetE lifting-surface mean aerodynamic chord (M.A.C.)L lift in poundsD drag in poundsV velocity in feet per secondVk velocity in knotsP power in pound-feet per secondW vehicle weight in poundsS reference momentum area in square feet \---2m 4d propeller diameter in feetn rotational speed in revolutions per secondc propeller airfoil sect ion lift coefficientLV equivalent lift-drag ratioP

P -power parameter

wV

- speed parameter

M vehicle Mach numberpropeller tip helical Mach numberpropeller reference blade angle

p atmospheric air density in slugs per cubic footpropulsive efficiencypropulsive efficiency at subcritical tip Mach numbers,

incompressibeTinax maximum propulsive efficiency ratio, compressible-to-1i incompressibhl

iii --

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iRL

Normal maximum continuous engine power settingRated

Mil m ilitary engine powet settingTO take-off engine power settingTP-SS engine, turboprop, single shaftTP-DS engine, turboprop, double shaftRTP-SS engine, regenerative turboprop, single shaftRTP-DS engine, regenerat ive turboprop, double shaftAF U auxiliary power unitRest condit ion of waterborne ASW tactical surveil lance

iv

: PRNC-GEN-175 (Rev

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TABLE OF CONTENTSPage

SYMBOLS iii-ivSUMMARY 1INTRODUCTION 1DESIGN CONSIDERATIONS 2VEHICLE CONFIGURATION 2

PREDICTED PERFORMANCE 3PROPULSION CONSIDERATIONS 3

PERFORMANCE TRADEOFFS 6WIND-TUNNEL TESTS 7AIRCRAFT SYSTEMS 7ASW MISSIONS 9

CONTACT MAINTENANCE 9COMTUTER SIMULATION 10COMPUTER RESULTS 13

CONTACT INVESTIGATION 15TEMPORARY BARRIER 17

SPECIAL-PURPOSE VEHICLE 18CONCLUSIONS AND RECOMMENDATIONS 18REFERENCES 21

LIST OF TABLESTable 1 - Aircraft Physical Characteristics 23-24Table 2 - Summary of Submarine Tactics and Aircraft Fuel 25

ConsumptionLIST OF ILLUSTRATIONS

Figure 1 - Nondimensional VTOL Vehicle Comparison of Equivalent 26Lift-Drag Ratio Versus Speed

Figure 2 - Classical Propulsion System Loading for Hover Flight 27Figure 3 - V/STOL Seaplane in Cruise Configuration 28Figure 4 - Principal Dimensions of th e Seaplane 29Figure 5 - Nondimensional VTOL Vehicle Comparison Including 30th e Seaplane DesignFivtlrc 6 - Nondimensional Performance of Power Versus Speed 31

Parameters

v

I IRev. 12-55,

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TABLE OF CONTENTS (Concluded)LIST OF ILLUSTrPATIONS (Concluded)

PageFigure 7 - Effect of Compressibility on Propeller Efficiency 32Figure 8 - Turboprop Engine Characterist ics 33Figure 9 - Cruise Performance With Six Engines at 35-Percent 34

Normal Rated PowerFigure 10 - The 1/20-Scale Unpowered Model in th e Cruise Confi- 35

gurat ionFigure 11 - The 1/20-Scale Powered Model in the Hover Configu- 36rationFigure 12 - Air Transportable Sound Surveillance System (ATSSS) 37Figure 1.3 - Artist's Conception of V/STOL Seaplane in a Func- 38

t ional LayoutFigure 14 - Sequence fo r Change of Mission Command 39Figure 15 - Basic Tracking Mission in Contact Maintenance 40Figure 16 - Computer Simulation 41Figure 17 - Sonar Characterist ics for True Range and Probability 42

CalculationsFigure 18 - Basic Tracking Mission Following a Tactical Maneuver 43Figure 19 - On-Station Maneuver Sequence 44Figure 20 - Air Drop of ATSSS Buoy 45Figure 21 - Drop Pattern (Archimedes' Spiral) for Contact 46

InvestigationFigure 22 - Entrapment Probability in Contact Investigation 47

viPRNC-CEN-175 (Rev. 1

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loo

SUMMARYA V/STOL Open-Ocean Seaplane with good payload/range capabili ty

and high seaworthiness characteristics has been investigated for specifASW missions. fhe results from a simulation program of the contactmaintenance mission on the IBM 7090 computer, using th e predicted per-formance of the seaplane design and the projected capability of th e AirTransportable Sound Surveillance System (ATSSS), indicate a good poten-tial fo r tic s,:aplane in passively tracking of on-stat ion nuclear sub-marines. The applicat ion of the seaplane to other ASW missions (contacinvestigatio n and th e temporary barrier) is also considered. The speciconfiguration l imitat ions and performance considerations involved in thpreliminary design of the 93,000-pound V/STOL seaplane are outlined.

INTRODUCTIONThe Aerodynamics Laboratory of the David Taylor Model Basin has

heen involved in th e research and development of Vertical and Short TakOff and Lwnding (V/STOL) Aircraft fo r the past fifteen years. However,only in th e last two years has a concentrated effort been devoted toconceptual design. This two-year period started with a review of th einformation available from earlier test and development programs in th eV/STOL field.

Figure is th e result of a performance estimate for several con-cepts, including a modern t i lt-wing t ransport . It .s a plot of th eequivalent lift/drag ratio versus a nondimensional speed parameter, es-sentiallv a power-required concept. Notice that the early V/STOL con-copts produced maximum lift/drag ratios of less than 4. It must berciembered that these were, essentially, test-bed vehicles, and were notde,signed fo r optimum cruising performance. However, compared with th ehetlicoptcr, te esc vehicles were less efficient cruise machines; and,since this type of vehicle is always a less efficient device in hoveringflight, they represented no specific advantage, except fo r speed. Also,th ( speed capal)i t iLes which many of them possessed could no t be utilized

io a m ititar- ' cnoironment because the payload vanished in th e fuel re -I i r(:'mt Only the tilt-w iog transport showed any promise of being an

, vehici e (Refereuict. 1).

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DESIGN CONSIDERATIONSFrom these available data, th e Aerodynamics Laboratory staff s

up certain study criteria. They were: that th e payload/range charistics of any designed vehicle are paramount, that th e design mustan evolutionary development of standard aircraft design practice, anthat an equivalent lift/drag ratio of less than 10 would automaticadisqualify a primarily load-carrying vehicle. The transition characteristics were to be subordinated, although not neglected, in favorincreasing the cruise potential. The initial considerat ions for deconcepts and mission formats led to severe l imitations on configuraThe aircraft in question could not be made clean enough, aerodynamito give a fair evaluation of the efficiency potential of future V/STconcepts. The outgrowth of this dilemma was a diversion of attentioan Open-Ocean Seaplane, where configurat ion l imitations were minima

The primary design consideration was the selection of the propgroup. Figure 2 is th e classical power-loading/disc-loading curvehovering flight (Reference 2). In the low disc-loading area at theof the curve, rpresenting the region of helicopters, successful opover water has been performed. The jet-surface loadings associatedjet-lift systems, shown at th e right of the curve, are expected tohigh fo r a vehicle to exhibit satisfactory handling qual i t ies in aenvironment. Although it has not been satisfactorily evaluated to it is assumed that an allowable disc loading of 50 pounds per squareis compatible with water surfacc operations. The problems identifiewith operation in a marine eniironment need further clarification; afull-scale testing is probably necessary to establish a definite disloading boundary. The selection of 50 pounds per square foot indicath e desirability of a free-propeller configurat ion. With this hoverloading, a 90,000- to 100,000-pound vehicle could be supported by si20-foot-diameter propellers.

VEHICLE CONFIGURATIONThe resulting vehicle configurat ion (Figure 3) is a six-engine

canard seaplane with a fully developed hull to accommodate the STOLrrequirement The aircraft is about the size of a P3-A (ORION).

-2-

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-- L

The canard arrangement gives a location fo r the six engines withinreasonable structural considerations and offers the advantage of longi-tudinal trim control in hover and transition without the use of a tailrotor. The vertical and short take-off lifting capabilities of theaircraft are considered to be 93,000 and 115,000 pounds, respectively,The "no fuel" operational weight should be about 81,000 pounds. Figurepresents the major dimensions of the seaplane in a two-view drawing, andTable 1 summarizes additionai configuration specifications.PREDICTED PERFORMANCE

Figure 5 shows the predicted performance of the DTMB seaplane incomparison with the early vehicles. It is noted that the predicted equivalent lift/drag ratio is in excess of 10, the initial limit for accepta-bil.:y. The value used fo r propulsive efficiency was 0.80 in the generaof the seaplane curve. These data can be Uiewed in a modified form, thenondimensional power versus speed parameter, as shown in Figure 6. Lookat the data in this manner leads to the often-stated argument that thecruise power requirements fo r VTOL aircraft are about one-third of theinstalled power. This observation immediately suggests that with a six-engine vehicle, cruise might be effected with two engines at high power,four engines at medium power, or six engines at low power. An investiga-tion of the propulsive efficiencies and fuel consumptions of various engcombinations is required to establish the most efficient operation. Maintaining a high performance level is dependent upon maintaining high pro-pulsive efficiency fo r all flight requirements. Very clean aircraft withinefficient propulsive systems will show up poorly when compared withwell-matched powerplant/airframe combin tions.

PROPULSION CONSIDERATIONSThe curves of Figure 7 indicate how the maximum propulsive efiicienc

is dograded as the tip Mach number of the propeller is increased beyond0.9 (Reference 3). These curves do not take into account the most recentt. techno logy in contemporary propeller deSign which ITaV include using variageonlevt y to achieve hiih stat ic t h rust with i minimum comproomiist of c ruise

t fficinercN. Excluding thle 1erits oi the vet unproved variahle-geometryproe l ers, thit, curves do ind icat that( in thie des ig!n of a freepropel le r

-3

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VTOL vehicle (where static conditions dictate the selection of propediameter and power train gearing), seemingly well-matched propellersmay not retain a high propulsive efficiency when operating at an altcruise condition. If the tip speeds are not maintai ed near a maximpermissible level in the hover condition, wnere the demands on the ppulsion system are the greatest, there will necessarily be a weightpenalty in the entire propulsive group. Assuming that this requiremeexists for the particular design under consideration, one should looat the resulting tip speeds under crnising flight conditions. The ppeller helical tip Mach number fir the forward flight condition is g'y:

MT = M(, /) + 1

At the cruising altitudes and speeds considered for most ASW miprofiles, the aircraft cruise Mach number would be between 0.4 and 0To avoid the compressible flow losses associated with operating a contional propeller above a tip Mach number of 0.9, one or more of thevariables appearing in the expression must be decreased. With a giveflight speed and altitude, and the propeller diameter fixed, only engrotational speed (n ) can be diminished. Old piston engines providedthis reduction in r~m for the cruise power settings; however, simplemachinery, running at nearly constant rpm for any power setting, doesThe conclusion i'-, be drawn that efficient VTOL aircraft may requirecomplex engines.

Fig~ure 8 shows the character is tic propel Ic r shaft Speed reduc t ioof four turboprop elgignes as a functi," .f percent normal-rated powerThe single-shaft turboprop (TP-SS' engine shows no speed reduction wa dec ri-ase in power. The doulbi -shaft t urhoprop , or tree-turbine (TPengi ne, shows almost 20 percC'lt rot2tiOnal speed reduction alt "4 pe 1power; and the single-shaft rcgcnerati vt (RTP-SS) tnu it e shows a sirui

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speed reduction at 35 percent normal rated power (see References 4through 6). The curve also shows an RTP-DS engine with approximately30 percent reduction in turbine speed at low power. Such an enginewould be a free turbine with a regenerative cycle. This engine issuggested as the type which may be necessary to optimize performanceover the large span of flight requirements for VTOL aircraft, includingvertical take-off and high-speed cruise.

In addition to considering turbine speed, which changes air horse-power output through the propeller efficiency, it is necessary to considthe specilic fuel consurntion (sfc) at desirable power settings. Th edesirable effect of reducing turbine speed at low power will be lost ifthe engine sfc is high. For example, turbine speed characteristics ofthe free turbine (TP-DS) shown are nearly satisfactory with the engineoperating near 40 percent power. However, the sfc at this power settingis approximately 30 percent higher than the sfc at full power. At ap-proximately the same low percent power, the sfc of the regenerative turb(R'rP-SS) is significantly lower than that at full power (approximately 1percent). With all stages of th e single-shaft regenerative engine interconnected, this engine does no t offer th e ultim ate in turbine output specharacteristics. The engine suggested as desirable for free-propellerVTOL aircraft would essentially incorporate the best features of the freturbine (speed relaxati on) and th e regenerative cycle (low sfc at lowpower). This is probably a complex engine with variable geometry in botends of the gas cycle.

If the cruise speeds fo r the aircraft require th e maximum reductionin ,ngine rotat ional speed to ulaintain high propulsive efficiencies, theone sho lId consider that Cllginc- power in cruise may be reduced to as lowas 15 per-celt of normali ratted power. The turbine characterist ics wouldthen indicatt, that under most conditions this six-engine aircraft shouldbe cruised with all encines rnllllning Lt the lowest power sett ing. Someconsi doration 11111 bht given to four-engine opcr-a ion, but it is believedt lilt ;lICCLs t o- two-t cu i t, operat i o) ill tOlt' eflficient cru'lise range wotuldht. to)() 1ow fo r t he pro o)ted requirements of t his aircraft.

S- go h

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Many VTOL" design concepts have not given serious consideration topropulsive efficiency in cruise. Looking at this problem fo r each indi-vidual design makes many of them unacceptable.

Performance predict ions for this vehicle have been made using th eengine specifications of a single-shaft, regenerative turboprop engine(Reference 6). The regenerative turboprop is considered to be a reasonabst-t-of-the-art engine development, although no engines of this type arep'esntly in service.PERFORMANCE TRADEOFFS

Whmn attcnf ion is diie-ted toward a specific aircraft speed, it isnecessary to select the operating point on th e power/speed curve orequivalent lift/drag curve. If payload/range characteristics are ofprimary importance, cruise must be at the maximum equivalent L/D. Cruisiat (L/D) a is possible fo r all aircraft, but it often requires flying atmaxhigher altitudes or lower speeds than are desirable. Flying at (L/D)maxis not considered for the seaplane, Recommendations issued by Air ProgramNaval Application Group of th e Office of Naval Research indicate thata cruise speed of the order of 300 knots, or greater, is desirable formost ASW missions (Reference 7). To approach a speed of 300 knots withinaltitude l imits, it is necessary to fly th e seaplane "off" (L/D) max; thatis, off its most efficient cruise point. A performance analysis has beencompleted to weigh the t radeoffs in payload/range against an increase inspeed. A sl ight reduction in aerodynamic efficiency results in a pro-portionLi increase in th e fuel requirement. This vehicle should be capabof accepting th e penalty of flying "off design" to achieve acceptablecruise speeds. The additional fuel load required will not make the vehicoverweight if the, initial take-off is assumed to be in the short iake-offmode. It is tihe vertical take-off or vert ica l landing weight that repre-sents the l imit ing weight of the aircraft. It wil l be necessary to fuelthe aircraft with a specific mission in mind so that transit fuel burn-off will allow arrival in the tactical area at design VTOL weight.

Fiyre 9 shows the aircraft's performance at variGus weights foran eqtiivalent lift/drag ratio of 10.35. The two curves which define th e

-6(--

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performance of the airplane, within propeller-tip Mach-number limitsof 0.9, are the predicted performance of a regenerative turboprop(RTP-SS) and the hypothetical VTOL engine (RTP-DS). With the regener-ative turboprop, speeds from 260 to 290 knots are attainable at altitudesfrom 21,000 to 16,000 feet. At these speeds, the specific range ofthe aircraft, in miles per pound of fuel, is almost constant at 0.095.The hypothetical engine allows a significant improvement in aircraftefficiency, but only by operating at very high altitudes (above 25,000feet). These altitudes are no t considered consistent with missionrequirements. Furthermore, the hypothetical engine installation doesno t produce a significant increase in the seaplane cruise speed.

WIND-TUNNEL TESTSWind-tunnel tests have been conducted in the 8- by 10-foot subsonicfacilities at the Aerodynamics Laboratory, Taylor Model Basin to determin

the handling qualities, transition stability and control, and flight performance of the V/STOL seaplane. Figure 10 shows the unpowered versionthe model in its cruise configuration. Figure 11 shows the powered modelin the hover mode. These tests involve tilting the wings to establish thtrim conditions throughout the transition phase of flight.

Results of the tunnel tests to date indicate that the configuration,as shown, demonstrates slight static longitudinal instability in cruise.The drag measurements, when compared with finite wing theory, substantiatthe prediction that the downwash from the canard destroyed the ellipticlift distribution on the main wing. Results of the wind-tunnel testsfo r thf! seaplane cruise performance are reported in Reference 6, and areport of transition characteristics is in preparation.

It is predicted that a modification in the aircraft geometry canresult in a substantial resolution of these prcblems. A small investiga-tion for the optimization of high-aspect-ratio canard configurationgeometry is planned. AIRCRAFT SYSTEMS

In discussion with personnel in the ASW Office of the Bureau of NavaWeapons, the suggestion was made that consideration be given to the Air

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Transportable Sound S-rveillance System (ATSSS) buoy concept, the activepassive unit now under development (Reference 9). This system would provide the aircraft with multi-sensor deployment; it would prevent datadegradation from tuowing effects; and it should give unbroken target con-tact during aircraft manueverso The ATSSS buoy is shown in Figure 12 .While the ATSSS concept considers both active and passive operation, itwas further suggested that if the system were to be used only passivelyfor target tracking, a buoy designed fo r purely passive operation mighthave only half the weight of the ATSSS system (about 1,500 pounds),a three-fold increase in battery life could be expected (permittingnearly 24 hours of operation), and the bearing accuracy might beimproved in the passive mode to 3. The cyclic operation would be ap-proximately the same as the initial ATSSS concept--15 minutes to lowerthe array and 30 minutes to raise it. It is assumed that The size wouldremain the same as that of the original buoy concept. It is further considered that a modified A-New Data Handling System would be incorporatedin the airplane. The system modifications would delete items not re--quired to perform. the mission selected. Other systems considered fo r thaircraft are: a limited Jezebel capability, 180 0 -scan radar, low-light-leTV, and automatic ECM.

An artist's conception of the seaplane in a functional layout ispresented in Figure 13 . The seaplane is shown sitting on inflatablevertical floats. The tactical layout is considered to be a Mod-2 A-Newsystem. Volume requirements for specified equipment have been considereusing standard aircraft rack sizes. Minimum personnel requirements woulinclude: a three-man flight crew, a five-man tactical crew, and a buoyhandler. The inset, Figure 13, shows the stowage location fo r four buoytwo aft of the main wing and two in a trough under the floor of the datacompartment. These buoys will be ejected and retrieved through a buoyshoot aft of the main support float. A large portion of buoy handlingwould have to be done with automated power equipment because of theirweight and size. Proposals are in existence whereby buoy deploymentand retrieval should be operationally feasible.

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ASW MISSIONSThe seaplane has been considered for three ASW missions: contact

maintenance (tracking), contact investigation, and the temporary barriIt is not implied specifically that the seaplane cannot perform suchmissions as convoy and task-force screening, amphibious area screen.ingand open-ocean search. It is, however, believed that these missions cbe more economically performed by other vehicle systems.CONTACT MAINTENANCE

The principal mission for the seaplane is considered to bE that omaintaining contact with enemy nuclear submarines fo r extended timeperiods. It is further considered that continuous tracking would be ina passive mode of operation without the submarine being aware of theaircraft 's presence. Contact maintenance presupposes target localizatby some other means. Target localization by some other means signifiethat contact maintenance is essentially the take-over of a trackingcommand. Figure 14 shows the sequenace of events to complete a missioncommand change. Considering the case of a target 1,000 miles from thebase harbor, transit and buoy deployment--from cold start to rest--caneffected in 4 hours and 18 minutes. Near the end of the cruise-out legtransit, the tactical coordinator (TACCO) would initiate an interrogatof the computer on board the vehicle holding the target. This interro-gation would be done ia automatic radio data link, where the memory inthe tactical computer is read into the memory of the arriving aircraft.When the interrogation is completed, a data presentation is availableboth vehicles. Hence, a determination of the most effective buoy deploment can be made by the arriving TACCO. This degree of coordinationallows the arriving aircraft to transition and effectively deploy threeof its four buoys in the 4 hours and 18 minutes.

The basic tracking or contact maintenance mission is shown in Fig-ure 15. It is believed that this coverage represents a satisfactorylevel of passive localization, if attack is not imminent. The aircraftis sitting at position 1, with buoy I on board. Buoys 2, 3, and 4 aredeployed. The circles around each buoy represent the acoustical range(24 kiloyards) for 40 percent detection probability against a 5-knot

-9-

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submarine. Notice that buoy 2 is rapidly becoming useless to th etactical situation, since its detect ion probability is down to 20 per-cent. These percentages, functions of buoy detect ion range and submarinspeed, form th e basis fo r an assessment of th e tactical situation in amathematical analysis.

The detect ion probabilities are used as a set of l imits for estab-lishing seaplane maneuvering requirements; ioe., th e percentage associatwith any one buoy must be at least 20, the percentages fo r any two buoysmust total 50, and the percentages for all three buoys must total 120oThese specific l imits, together with other "fix" quality criteria determthat the buoy deployment shown in Figure 15 is satisfactory and th e sea-plane should remain at rest.

In an actual passive tracking situation, signal strength in a givenenvironment is a function of submarine speed and th e signal is attenuateas a function of range. These acoust ical energy phenomena will influencthe quantity and quality of date available from any signal source. Theanalogy of the physical conditions to the mathematical treatment is obv

COMPUTER SIMULATION -- The computer simulation -is detailed in th efollowing paragraphs.

Initial Condition3 -- It is obvious that problem analysis becomesquite complex if all factors covering the status of the submarine, thebuoys, and th e aircraft are to be invest igated over long periods of timeFo r this reason a simulation procedure fo r the IBM 7090 computer has beedevised. Thus far, it has been applied to the contact maintenance of anon-station enemy nuclear submarine. It is assumed that the submarine ismaneuvering in a non-ordered pattern, at speeds from 0 to 5 knots. Thistactical situation is believed to represent a very difficult trackingassignment fo r an airborne :;vstem. A simple representat ion of the compsimulation is shown in Figure 16. Initial conditions are establ ished byrandom selection of the submarine true-course, speed, and duration on aparticular leg, In small time intervals, the computer updates th e truesubmarine data and the true buoy-submarine geometry, and determines de-tection probabilities. Detection probability is the index of dataavailability to the aircraft -IO-

VW -CGEH-1i75 (Re

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-ifLSensor Characteristics -- At this point, it is necessary to consider

sensor characteristics. In Figure 17, the assumed buoy characteristicsare presented. The curve at the left, lateral detection range, incorpo-rates the assumption that at zero speed, a nuclear submarine will generatesome machinery noise from pumps and generators and can be assigned afinite detection range (10 kiloyards). At a 15-knot transit speed, it isassumed that the submarine is detectable at 40 kiloyards. The detectionrange is assumed constant beyond 20 nautical miles because of convergenceassociated with the reliable acoustic path. The right-hand side of th ecurve is essentially the transmission-loss curve, smoothed for computa-tion. It reflects the logarithmic variation associated with sonar devices

Data Availability -- Returning to Figure 16, a random number system,indexed to probability, dictates when tactical data are available to theaircraft (Reference 10). Under actual tactical conditions, data wouldprobably be available only in bits and pieces. The random system simu-lates the real data availability quite well. The aircraft side of thecomputer analyzes the data given, and decides whether maneuvering is re-quired. It then updates the aircraft's status accordingly. Arbitrarystatistical rules for aircraft maneuvering must be established as programinputs, and the aircraft can only maneuver within the constraints of theinitial input parameters. While the program remains flexible and canincorporate nearly any maneuver that can be expressed mathematically, thecomputer will exercise that maneuver only when the criterion for therequired maneuver is satisfied. A human TACCO could exercise judgmentand, in some cases, would delay, abort, or completely eliminate maneuvers,a choice not available in this simulation program.

Aircraft Maneuvers -- In any tactical situation, unless the submarineis sitting, the relative position of the submarine with respect to thebuoys changes constantly. The TACCO monitoring the situation should ordermaneuvers as the confidence level of the data presentation reaches somelower limit. Figure 18 shows a typical maneuver. It is an extensionof the earlier passive localization case. The figure shows the aircraftflying from it s original position 1 (a t the lowr left) and depositingbuoy 1 (which was on board) ahead and beside the predicted track of the

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submarine. At this time, the deep unit of buoy 2 is commanded to rise,via the UHF command link, and the pilot flys the aircraft to the positionof buoy 2 fo r retrieval. The sequence of events fo r an on-station maneuvis given in Figure 19.

The frequency of aircraft maneuvers is controlled by the necessityof continuously maintaining a satisfactory level of target localization.If some minimum level is violated, there is a high risk of losing thetarget. Therefore, buoys must be periodically moved to a new locationthat will hold the target satisfactorily. A total of 120 percent cumulaprobabiliLy on three buoys was shown in Figure 15 . The total of 140 per-cent immediately after an aircraft maneuver, as given in Figure 18 , proviadditional target coverage so that another buoy replacement would not berequired fo r some time.

Probability, which is a measure of target distance corrected forsignal strength due to target speed, is not the single basis fo r determi-nation of buoy replacement. The intersection angle between the detectingrays from pairs of buoys nmsL also be considered. For example, althoughthe signal strength ma y be high when the distance between a buoy and thetarget is small, no accurate target fix can be made if the lines of signatransmission are nearly parallel, The computer simulation takes accountthis quality reduction in the fix.

A technique for handling a target lost during a tracking mission hasbeen incorporated into the simulation program. Ideally, the "go lost"route would not be implemented if the aircraft sensor system is trackingproperly. However, after certain sporadic changes in target speed orcourse, the available data from a conventional buoy deployment patternare unsatisfactory, and a special pattern is required. The recommendedtracking procedure, then, is to hold the target as loosely as possible,minimizing the number of buioy movwments required, while reestablishing thoasir contact pattern. Here th& seaplane accepts a slightly higher riskof belhng detected by deploying the buoy on board at a range of 10 kiloyarfrom the predicted position of the target, The probability that theseeilane will be detected in the hover mode at this range is about 10percent. The scaplane immediately returns to the most remote buoy. A

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second alteration to standard procedure was that the remote buoy wascommanded to rise immediately when the "go lost" routine was ordered.

During on-station maneuvers, the index of sea-state conditiondetermines the take-oif, drop, and landing modes of the aircraft. Wheresea states are low, short take-offs and landings would be used to con-serve fuel. In the digital program, the dividing line fo r VTOL maneuverswas between sea states 3 and 4. Fuel consumption, per manuever, is quitehigh in either case because of the full power required fo r take-off andlanding; however, a nominal saving is experienced in STOL operations.It is the length of time between maneuvers, not the amount of fuel permaneuver, that makes the system competitive on the basis of pounds of fuelburned per hour. Typical transit distances involved in an on-stationmaneuver are 30 to 80 nautical miles. The time per maneuver is usually20 to 35 minutes. While the aircraft is maneuvering, there may be atemporary break in the line-of-sight data link between buoy and aircraft.Should this interruption occupy a significant time interval, the buoys mayrequire a short-term tape memory 6ystem which could be interrogated whenthe data link is reestablished.

COMPUTER RESULTS -- Several thousand hours of simulated tracking havebeen completed on the IBM 7090. Table 2 is a summary of some submarinetrack patterns and the fuel used by the seaplane while it was maintainingtarget contact. The seaplane had maneuvered essentially as shown inFigure 16 throughout the time spans considered.

Because the submarine tracks are generated from random inputs, itis difficult to assess which submarine maneuvers present the most exactingtracking problem for the seaplane sensor system. The average hourly fuelconsumption of the seaplane, which depends primarily upon the number ofmaneuvers required, should be weighed heavily in estimating the moredifficult cases.

The number of times the target is lost may also prove to be a goodindication of the difficulty of maintaining continuous contact. Ingeneral, the results show that any submarine track which includes abruptchanges ini signal strength (speed change) or quality of fix (bearing changwould present the more difficult tracking problems for a tactical coordina

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A comparison of the fuel used by the seaplane, per hour of tracking,with that of contemporary airborne tracking systems shows that the sea-plane represents a substantial improvement. No direct comparison ismade regarding the relative merit of the seaplane versus the conventionalfixed-wing aircraft in stdying with a target. It may be stated, however,that tracking an on-station submarine with magnetic-anomaly detection(MAD) gear represents a considerably more difficult assignment, and inthe assumed time frame may be impossible.

Looking at the amount of fuel burned per hour would indicate thatthe seaplane should be capable of staying on-station for extended timeperiods. Crew endurance rather than fuel limitation may then become themeasure of mission length. A double, or nearly double, crew may be re-quired to realize the full mission potential of the aircraft. Unfortu-nately, accomodation of a double crew requires further vehicle growth.

In one mission that was assumed to have a mean level of fuel con-sumption, 35 hours transpired from crew briefing to debriefing. The timin actual tracking operations was 21 hours, during which 14,000 poundsof fuel was burned. This schedule produces about 60 percent useful uti-lization of mission time; but it required coordinated refuelings withthe previous and following seaplanes, and duty assignments inconsistentwith the number of personnel on board.

One additional aspect of the data available to the TACCO showedthat the quality of the fix varied. A part of the simulation results wasa displacement and bearing error in the predicted target position. Thehuman operator would see the geometry of target-buoy deployment, as itwould be displayed on the TACCO console in the real mission. There arepatterns which yield high quality fixes and those of low quality--thus,the display is a quality index. It is most significant that the posi-tioning errors fo r the :0 bearing accuracy, assumed fo r the buoy, iswell within the acquisition range of present weapons when the quality offix is high.A simulation of the contact maintenance problem on the IBM 7090computer is not intended to be a final statement of the case fo r theASW mission. All of the inputs used in the program %ere based upon the

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best information available. However, in many cases th e system charac-teristics had not been sufficiently defined to assign an absolute valueto specific parameters.

The random number and probabili ty technique used to generate sub-marine tracks and assess data availability is followed in lieu of asatisfactory definition of enemy submarine tactics and final sensorcapabili ty. If an estimate of th e length of time and the accuracy withwhich a tracking mission could be carried out resulted, th e computersimulation has then served the intended purpose of providing a set ofguidelines to evaluate the concept. The final usefulness of th e seaplaconcept can be appreciated only by allowing th e appropriate sub-systemexperts an opportunity to evaluate th e results; and from such an evalu-ation, to establish practical l imitations for application of th e concepto specific Navy requirements.CONTACT INVESTIGATION

The second major ASW problem compatible with th e seaplane is thatcontact investigation. As initially considered, this mission would beconducted in conjunction with a t ransport aircraft. An early disclosurof th e ATSSS proposal showed a parachute deployment of the buoy from thP-3 aircraft, as shown in Figure 20. The seaplane would be th e tacticavehicle, and would carry only two ATSSS buoys. The transport would bebuoy carrier and would use parachute deployment. In addit ion, it isconsidered that the transport would carry additional fuel for th e seaplThe t ransport requires the addit ion of accurate navigation equipment sothat deployment can be made in a very accurate manner.

To establish th e framework for this mission, a series of assumptiomust be made. It is assumed that a contact is reported, perhaps visualfrom an over-fl ight aircraft or from a small ship (o r fishing boat) maka periscope sighting. It is further assumed that this fix might have aposi t ioning error of as much as five nautical miles. The contact may ban acoust ical one from a fixed passive array in which th e initial posi-tioning error may be 50 nautical miles. Since the data from th e acouscontact can be updated constantly as th e airplane progresses on the out-ward track, the mission for the visual sighting of a 15-knot transiter

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nMOP-

that of the acoustical contact are not markedly different. A thirdassumption considers that the area commander has placed a very highpriority on entrapment of this target. Finally, it is assumed thatthis type of mission is ordinarily carried out and that there are air-craft and crews on immediate standby status.

Figure 21 represents a visual contact, which is assumed to be 600miles from base. The lateral detection range of the active ATSS, forthe geographical area considered, is assumed to be 30 kiloyards in 1,500fathoms of water. The mission commander ascribes a speed to the contactand this speed establishes the level of effort. In the figure it isassumed that a transit speed of 15 knots has been assigned. The seaplanand trinsport cruise speeds were 275 knots and 325 knots, respectively;however, both aircraft are dispatched together. Although the transportarrives in the tactical area and begins deployment of buoys on theArchimedes' spiral prior to arrival of the seaplane, the seaplane will bwithin monitoring distance when the first buoy data are available. Theseaplane proceeds into the area and deposits two buoys (Is and 2s); thenlands beside buoy 2s fo r monitoring purposes. A detection picket fenceessentially established with the planting of buoy 11, and the pattern cabe abandoned at any time a positive identification is established by anearlier buoy. The advantage of the twelfth buoy will be shown, subsequeIf the estimate of submarine transit speed was not low and the initial ctact area was not greater than the 75 square miles associated with thepositioning error (five nautical miles), then entrapment is quite certainIf the submarine should continue on any heading at 15 knots or less fromthe time of initial contact, then detection with this system would be ona matter of time. Figure 22 is an index of the probability of detectionas a function of the time after the first buoy is dropped. The specificassumption is that the subrmarine did transit at 15 knots, along any giveheading, from the time of initial contact until the barrier was intercepThis is a very specific case, which is only remotely realistic. Actuallythe submarine would, in all probability, exercise evasive tactics. Itcan be assumed that the submarine would have a better acoustical range

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than the buoys (through the use of a conformal array or some othertechnique), and therefore could identify the active buoys beyond thebuoy detection range. However, the entrapment fence would be closedbefore escape could be effected. If the submarine were to continue itsevasive tactics, sanitizing the center region might be necessary. Thcan be done with buoys presently on hand--hence, buoy 12--but an addi-tional fuel suFply would be necessary fo r the seaplane. Several facetthis seaplane operation dictate that the seaplane should be capable ofair-to-air refueling from a transport tanker. With this capability, tseaplane (with the buoys already deployeJ1 in the water) can sanitize tcenter area in 12 buoy movements, requiring approxLmacel. tour hours orather difficult work.

This mission has been considered as requiring active ATSSS (3,000pound buoys) to prevent escape of the most quiet boats. It may be reathat the 15-knot transiter is sufficiently noisy to allow the use of pmode buoys. This would have the a.dvantage of denying deployment infortion to the target and establishing the entrapment fence with less expsive buoys.

Perhaps the initial assessmnent of target threat should include anassumption as to boat propalsion system. The quiet diesel-electric sy

* might require the more expensive active-buoy system; but concurrently,the transit speed assessmetit will lower the level of effort applied.Obviously, it is difficult fo r the aircraft designer to more than sugga mission capability in this case, where tactical doctrine is so quest,able. The reality of this mission description is uniquely dependent ua doctrine committing a large expenditure of personnel and equipment tan individual entrapment.TEMPORARY BARRIER

The third ASW mission for which the seaplane is idea)ly suited isthe temporary barrier. This role takes advantage of worldwide deploymcapability of the seaplane in relatively short time. Reference 7 speca requirement for a 2,200-nautical-mile ferry range against a 5G-knothead wind as a performance level for this deployment. The seaplane demstrates this capability within the ll5,000-pound STO allowance, giving

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one hour reserve at a "loiter power" setting. Block time is of theorder of 10 hours fo r the fully operational configuration.

Specialized equipment and manpower support is a natural necessitof this mission. Providing this support would suggest the coordinateuse of transport aircraft. Where deployment is enhanced by high-speetransport capability, a variety of alterations in seaplane loadingexists; and no conjecture will be made as to best procedure.

Although this mission has not been detailed to any specific degrin this paper, it is not difficult to imagine that a contact investigtion network--in conjunction with the transport aircraft--could estababout 375 to 400 nautical miles of barrier net in a similar time framto that used in the contact investigation, if the transit legs were oorder of 600 miles. With these buoys deployed along a line, it wouldnecessary to use more than one seaplane to act as monitor. Further,a contact maintenance mission were to develop from a contact investigin the temporary barrier, then an additional seaplane (fitted with pabuoys) would necessarily be required. An airplane so configured coulused as the second monitoring aircraft by leaving the active barrierand concentrating on the contact maintenance, if that should be desir

SPECIAL-PURPOSE VEHICLEThe Navy has a variety of other missions where a seaplane, with

good seaworthiness, would be advantageous. These could be air-sea resubmarine resupply, command control, etc. After determining the weigof such a configured vehicle, the performance curves of Figure 9 couldapplied for a capability index. An exception exists in the case of asea rescue where a high "dash speed" may be required for the outboundAt the sacrifice of propeller efficiency, a dash speed of 355 knotsappears feasible. However, for a 1,000-nautical-mile mission radius,careful cruise control would be required on the return leg to completethe mission within the available fuel supply.

CONCLUSIONS AND RECOMMENDATIONSThe V/STOL seaplane with its specified svstems and predicted per-

formance would provide aii ASW capab ilitv not now available. This, to"" - 18 .- l r

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some extent, is dependent upon a presumption that the degree of sensorsophistication, to achieve the desired level of performance, requiresthat the buoys be inexpendable and that they be recovered a very highpercentage of the time.

Other recognized ASW systems appear to be much less suited to prolonged passive tracking. Only an airborne system (acoustically isolateor complex fixed-barrier arrays can amass large stores of signature dafo r target classification reference. Only such a self-sustaining airbsystem can remain with a target long enough to establish enemy tacticadoctrine. Both signature and tactics of a target aware of being trackmay be compromised by countermeasures. Achievement of the passive de-tection capability described in this paper will, thus, offer an importstep forward in the solution of the entire ASW problem.

To have an ASW vehicle/sensur combination like the V/STOL seaplanconcept ready fo r operational use in the 1970's, considerable work woube required in the following areas:

1.i Propulsiona. Engine development emphasizing low sfc at low power (regen

erative cycle) and turbine speed relaxation (double shafting).b. Propeller development, especially weight and structure,

including variable camber with supersonic tip design.c. Propeller environmentally designed for the recirculation

mediumn.2. Aerodynamics

a. A design study to establish weight and structural limits.b. Definition ot handling qualities through the transition

phase of flight.3. Sensors

a. Continuing development of air transportable systems.b. Attending to the development of a purely passive buoy.c. Leaving open the utilization of newly developed (non-

acoustic) sensor systems.

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4. Avionics (Navigation, Communication and Data Processing)a. Improvements in long and short range precisi a navigation.b. Relaying of tactical data through communication channels.c. Sophistication of data reduction, analysis, and display.

5. Seakeepinga. Development of a retractable inflatable float system,

recognizing specific stowing and structural problems.b. Testing various configurations to establish which wil give

the greatest attenuation of wave motion in the open-ocean; hopefullyallowing crews to operate effectively in sea state 5 or greater.

6. Naval Environmenta. Investigation of the particular handling problems involvedin operating over water at a disc loading of 50 pounds per square ifoot

(sea spray, dynamic and static stabi]ity).b. Determine the acoustic signature generated in all modes of

operation (hover, take-off, landing, sitting with only auxiliary power).Many of the development areas enumerated are included within the

continuing effort to improve existing systems, and only moderate alter-ations would be required to adapt these improvements to the seaplaneconcept. Other arcas, however, present problems peculiar to this vehicleand would require considerable innovations.

Aerodynamics LaboratoryDavid Taylor Model BasinWashington, D.C.september 1965

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REFERENCES1. Vought Aeronautics Div. (LTV Aerospace Corp.). XC-142A Performance

Data. Dallas, Jul 1963. lv. (various pagings)2. Rafner, R. Domain of the Convertible Rotor. Journal of Aircraft

(N.Y.), v.1, Nov-Dec 1964, p. 350-359.3. Stack, John, Eugene C. Draley, James B. Delano and L'is Feldman.

Investigation of th e NACA 4-(3)(08)-03 an d NACA 4-(3)(08)-045 Two-Blade Propellers a t Forward Mach Numbers to 0.725 to Determine th eEffects of Compressibility an d Solidity on Performance. Wash.,G.P.O., 1950. 32 p. incl. illus. (National Advisory Committeefor Aeronautics. Rpt. 999)

4. Allison Div. (General Motors Corp.) Navy Model T56-A-10W M ilitaryTurboprop Engine. Indianapolis* Aug 1962. 42 p. illus. (ModelSpecification 479-C)

5. General Electric Co. Engine, Aircraft , lurboshaft T64-GE-2 andT64-GE-6. Lynn, Mass., Mar 1961. [356] p. incl . illus. (ModelSpecification E1057)

6. Allison Div. (General Motors Corp.) Navy Models T78-A-2 and YT78-A-2M ilitary Regenerative Turboprop Engine [Title Unclassified].Indianapolis, Jul. 1963. 72 p. illus. (Model Specificat ion 649)

CGNFIDENTIAL7. Coates, L. D. Solicitation of Technical Inputs for Open Ocean AS W

Weapons System Feasibility Study [Title Unclassified]. Wash.,Mar 1964. [14] p. (Office of Naval Research ltr ONR:461:CWG:mebSer. 0482 of 23 Mar 1964 with Encl. (1)-(6)) CONFIDENTIAL

8. Thomas, Richard 0. Wind-Tunnel Investigation of a 1/20-ScalePowered Model Tilt-W ing V/STOL Seaplane in the Cruise ConfiguratioWash., Aug 1965. 32 1. incl. illus. (David Taylor Model Basin.Rpt. 2079. Aero Rpt. 1093) (DDC AD 472 709) CONFIDENTIAL

9. The Bunker-Ramo Corp. U.S. Navy A ir Transportable Sonar SurveillanSystem ATSSS (Title Unclasrified). Canoga Park, Calif,, Jun 1964.20 p. incl, illus. CONFIDENTIAL

"10. The Rand Corp. A Million Randum Digits With 100,000 Normal DeviateChicago, Free Press, 1955. 200 p.

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Ii. Dewey, D. B. Full-Scale Demonstration of the VerticalFloat Sea-Stabilization Concept. San Diego, Oct 1963.25 p. incl. illus. (General Dynamics/Convair GD/C-.63-200.Contract NOw 63-0793-f)

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Table IAircraft Physical Characteristics

Lifting Surfaces

WingArea in sq ft 1000Span in ft 100.0M.A.C. in ft 10.34Taper ratio 0.5Aspect ratio 10.0Dihedral in degrees

WS 0 to WS 195 0WS 195 to WS 600 5.5

Airfoil sectionRoot NACA 4412Tip NACA 4412

Flaps (plain) Aileron 0.20cCanard

Area in sq ft 250Span in ft 50.0M.AoC. in ft 5.17Taper ratio 0.5Asper* ratio 10.0Dihedral in degrees

WS 0 to WS 60 0WS 60 to WS 300 5.5

Airfoil sectionRoot NACA 4415Tip NACA 4412

Flaps (plain) Elevator 0.20c

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Table I (Concluded)

Vertical TailArea in sq ft 350Span in ft 24.5M.AoC. in ft 14.16Sweep (quarter-chord) in degrees 25Airfoi l section

Root NACA 0012Tip NACA 0008

Dorsal fin area in sq ft 42.0Rudder (plain flap): c r/c 0.30Rur1-- HullLength in ft 120Width in ft 10Height in ft 15Cabin volume in cu ft (approx.) 3000

Propellers (reenforced synthetic fiber)Diameter in ft 20.0Disc area (total) in sq ft 1884Solidity 0.13

Engines (regenerative turboprop type) (Allison T-78specifications increased 22 percent)

Power Setting in shpMilitary 4682Normal 4122

Vertical Floats (pneumatic; internally coiled)Diameter in ft

Wing-tip float 3.0Nose flcat 3.0C.G. float 7.0

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Table 2Summary of Submarine Tactics and Aircraft Fuel Consumption[0 to 5-knot submarine. Averaged over a 300-hour period]

Average Average SeaplaneCourse Course Fuel Con-Changes Duration sumptionin deg in hours in lb/hr

Predominately high and low speeds; 12 73 6.0 345.7stops taking 58.2 percent of timePredominately high and low speeds; 10 70 4.5 475.5stops taking 29.4 percent of timeEven distribution; 0-4 knots only; 19 70 3.1 507.0stops taking 32.5 percent of timeEven distribution; 0-4 knots only; 16 68 3.0 604.8stops taking 17.5 percent of timeEven distribution; 9 stops taking 58 4.0 616.821.8 percent of timeBiased slightly toward low speeds; 11 66 3.1 650.4stops taking 20.5 percent of time

Biased slightly toward low speeds; 11 70 4.5 682.2stops taking 9.3 percent of timeBiased slightly toward low speeds; 12 68 4.0 711.8stops taking 11.3 percent of time

Even distribution; no stops 70 3.1 730.0Predominately high and lov speeds; 11 75 6.0 803.2stops taking 12 percent of timeBiased slightly toward low speeds; 6 70 6.0 814.7stops taking 14.9 percent of timeEven distribution; no stops 70 4.0 898.8

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109

7'LV 6_P TILT-WING TRANSPORT

5 - - - -- (PREDICTED)-TANDEM HELO4 - -*-1 -I-------1-

#,,, -- CONVERTIBLE ROTOR2 - l VECTORED SLIPSTREAM

0 1 2 3 4 5 6 7 8 9V

Figure 1 - Nondimensional VTOL Vehicle Comparison ofEquivalent Lift-Drag Ratio versus Speed

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3.0

JET-. LIFT6- 2.0S2O LIFT

z FANS0 DUCTED-F PROPELLERS""i0.0 FREE-- ! LtJ3:PROP ELLERS 'o HELICOPTER

ROTORS0.0 r7 I - I 1 1 1 1I ,1 3 5 10 20 30 50 100 200 500 1000 2000 5000

DISC LOADING I" PSFFigure 2 - Classical Propulsion System Loading for [lover Flight

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C7)

-28-' QRCGM 15 (e

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T4o

337

6.2 5 16-2550.0 I D-- 900.0

S. . .---

-.H .7

Note:Dimensions are in feet. i3.3 -

h . . 23.4 -

81.1~~75.0 -28.8

24.9 - Z, -- 137- / / 24 5233 , - 6.8 /L2.92: . T ..-..-..... ......... M/i

15-0 ---- $"-- f.

216.3

Figure .1 - Principal Dimensions of the Seaplane

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12 -DTMB VTOL SEAPLANE

10-

- --7--- ___

TILT-WING TRANSPORTJ5 - (PREDICTED)

TANDEM HELO_ CONVERTIBLE ROTOR3--o m I I I..,

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2.8 "T -r-2.8 DUCTED FAN

2.42.0 =

SP 12.0 |--ECTORED SLIPSTREAMW\ ,m2TANDEM HELO

0.8 -.- * TILT-WINGTRANSPORTtt (PREDICTED)

0.4 - 1 CONVERTIBLE ROTOR 'DTMB VTOL SEAPLANES~(PREDICTED)10 1 2 3 4 56789

VVPSmFigure 6 - Nondimensional Performance of Power versus Speed Parameters

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CONFIDENTIAL

0 1.1E

S>" 0.9,T0.8

I-VU.XJ j FO R OFF DESIGN cS0.7 '0.5 0.6 0.7 0.8 0.9 1.0 1.1TIP MACH NUMBERMT:IE

Figure 7 - Effect of Compressibility on Propeller E fficiency

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--- - TP-SS TURBOPROP SINGLE SHAFT-.. TP-DS TURBOPROP DOUBLE SHAFT

RTP-DS REGENERATIVE TURBOPROP DOUBLE SHAFT (VTOL)-...... RTP-SS REGENERATIVE TURBOPROP SINGLE SHAFT

1009000

PERCENT ,TP-SS-MILRP M 70 RTP-DS-MILS70 TP-DS-MILTP-SS-TO60 - TP-DS-TO

50110 20 40 60 80 100 120 14PERCENT NORMAL RATED POWER

Figure TTurboprop Engi 'e Chnracteristics

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0.14z0.10

.1( .1

0.1z' 0.10

0.06 SEA LEEL_____j___

26 6 12208

720 -301 90" 10 11 120GROSS SEGT i0

Opr60oa 20,sed upo. L0/ = 03

-34-WEGT 1-

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0

05-

5-00Q5-

0

00V5-

0

rf

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-K-M

00

-36-

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-If

F.37

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-38-4

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ow I-tI- UI-0 w~

I UI 0Wj Ez0

_j 0 I L 0>u L)

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CONFIDENTIAL

SUBMARINE POSITION

-- =''(70%)

SBUOY 3 sww SUBMARINE TRACKS(30%) stam,,, PREDICTED TRACK(20%)

(I) AIRCRAFTPOSITIONFigure 15 - Basic Tracking Mission inContact Maintenance

Satisfactory level of passive localization, cumulative probability is 120 percent.The circles represent 40 percent detection for a S knot submarine.

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INITIAL CONDITIONS

TIME[TRUEUBMARINE COURSEBUOY DETECTION PROBABILITY SC

L AIRPLANE MANEUVERS

Figure 16 - Computer Simulation

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1-ILIoe UJ

I. c

0z

z0

S.LON)I AI)O-13A 3NiJvwals

PRNC-GEN-175 (Rev. 1

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CONFIDENTIAL

"Jo-

Zu,, I,

Go w 0

II =4L

So, .- o W0

Z>

oo 00a

0 CO;FIDENT

40

~06% :34)

0E 0

C0

z

CID

-43-CONFIDENTIAL "PRNC-GFN-175 (Re

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' lfVRTTOJ CRUISEI BUOY DROP

CRUISE VL/SL O

REMOTE BUOYFigure 19 - On-Station Manieuver Sequence

-44-PRMC-GEN-175 (Re

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,,, . . .

-

g '

/

u- .I

r

S

1.* I-45-

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TRANSPORT- SEAPLANE

CONTACT AREA

Figure 21 - Drop Pattern (Archimedes' Spiral)for Contact Investigation

--46-

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100

zLUm i0~

U 60 --. 4 0 -z

c 20 -S I I I I

0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0TIME IN HOURSFigure 22 - Entrapment Probability p, in Conitact investigation

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SopieG CopiesI DIR of Army Research j-6 R"10 Co.

(Attn: Physical Sciences Div.) -e Aron tti-c--Ree. Lab.- .-Cedar Rpfd.-1--owa1 CH European Res. OfficeU.S. Army R&D Liaison Grp. 1 Cornell. Aeronautical Lab.

(Attn: TC Liaison Officer) Buffalo, N.Y.20 DDC 1 Cu rtiss-Wright Corp.

VTOL Sys. Grp.I Avco Corp. Caldwell, New JerseyNew York, N.Y.I Cu rtiss-W right Corp.

1 Aerospace Corp. Wash., D.C.Los Angeles, Calif.(Attn: Lib. Tech. Doc. Grp.) I Cu rtiss-W right Corp.

Wright Aeronautical Div.1 Bell Aerospace Corp. Wood-Ridge, N.J.

Bell Aerosystems Div.Buffalo, N.Y. B- o Airaf -Co.(Attn: Tech. Libr.) Tore _- 4f.

1 Bell Aerospace Corp. 1 Douglas Aircraf t Co., Inc.Bell Helicopter Co. Airccaft Div.Fort Worth, Texas Long Beach, Calif .

1 Boeing Co. .1- .- Do"ug-AircxafL Go., Inc.Wichita, Kansas El Segundo, Div.(Attn: Chief Engr.) El Segundo,- Calif.

1 Boeing Co . 2 General Dynamics Corp.Transport Div. Convair Fort Worth Oper.Seattle, Wash. Fort Worth, Texas(Attn: Libr.) 1 General Dynamics Corp.I Boeing Co . Convair Div.Vertol Div. Dept. of Aero. Engrg.Morton, Pa. San Diego, Calif.

I booz-Allen Applied Res., Inc. 1 Genera. Electric Co.Bethesd& Md. FPD Tech. Info. Center

Cincinnati, Ohio1 Cessna Aircraft Co.

Res. Dept. I General Electric Co.Wichita, Kansas Small Acft. Engine Dept.West Lynu, Mass.

I Chrysler Corp.Defense Operations Div. General Motors Corp.Detroit , Mich. Nllison Div.(Attn: Lihr.) indianapolis, Indiana

(Attn: Engrg. ReE. Lib.)

-- )9---- i-PRMC-G[N*i7b (kev.

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__migCopies Copies2 Goodyear Aircraft Corp. I McDonnell Aircraft Corp.Akron, Ohio St. Louis, Mo.1 Grumman Aircraft Engrg. Corp. North American Aviation, IBethpage, L. I., N.Y. Autonetica Div.

Downey, Calif.1 Gyrodyne Co. of America, inc.Dept. of Aero. Engrg. I Noith American Aviation, ISt. James, L. I., N.Y. Columbus, OhioColumbuE Div..

1-Northrop Corp.Hawthorne, Calif.1 Hiller Aircraft Corp.Advanced Res. Dept. 1 Piasecki Aircraft Corp.Palo Alto, Calif. Philadelphia, Pa.1 Hughes Tool Co. 1 Republic Aviation Corp.Air-Craft Div. Farmingdale, L. I., N.Y.Culver City, Calif. (Attn: Mil. Contr. Dept.)(Attn: Chief, Tech. Engrg.)

1 Rocketdyne Div.1 Kaman Aircraft Corp. North American Aviation, InBloomfield, Conn. Canoga Park, Calif.I Kellett Aircraft Corp. 1 Ryan Aeronautical Co .Willow Grove, Pa . San Diego, Calif.

(Attn: Chief Engineer)* P~~nier-A ircref -Gp-.Xarlto~z, N.J. 1 Solar Aircraft Co.San Diego, Calif.1 LTV Vought Aeronautics Div.Dallas, Texas United Aircraft Corp.Pratt & Whitney Acft.1 Lockheed Aircraft Corp. East Hartford, Conn.Lockheed-Cal iforniaBurbank, Calif. I United Aircraft Corp.Sikorsky Aircraft Div.1 Lockheed Aircraft Corp. Stratford, Conn.Lockheed-Georgia Co.M arietta, Ga. 1 United Aircraft Corp.Res. Dept.2 Martin-iAarietta Corp. East Hartford, Conn.Bahtimore, Md. - Vanguard Air & Marine Corp.1 Martin-Marietta Corp. Bala Cynwyd, Pa.Orlando Div.Orlando, Fla. 1 Harlan D. FowlerBurlingarne, Calif.

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CopiesI Catholic Univ.-Dept. of Mech. and

Aero. Engrg.-L .. IT; t"Tg7a ry

_ University of Md.Dept. of Aero. Engrg.1 Miss. State CollegeAerophysics Dept.1 Princeton Univ.

Forrestal Res. Center(Attn: Libr.)

1 Virginia Poly. Inst.Carol M. Newman Library

1 Commandant, U.S. MarineCorps (A04E)

G-4 Div., Washa., D.C.I The Garrett Corp.

Airesearch Mfg. Co.Phoenix, Arizona(Attn: L.ibra-E I(iavn)

S-5]. PRNC-UENI-175 (Rev.

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S. JNCI.ASSIFIEDSecurity Classification DOCUMENT CONTROL DATA - R&D(Security lOtaasllcatiar, of title, body of abatract and indexing annotation must be entered when the overall report is classified)

I ORIGINATING ACTIVITY (Corperyat; author) 2 1 LASSIFICATIFAerodynamics Laboratory

David Taylor Model Basin 2b GRoupWashington, D. C. 20007 4

3 REPORT TITLE

AN OPEN-OCEAN V/STOL SEAPLANE FOR THE ASW MISSION (U)4. DESCRIPTIVE NOTES (rype of report and inclusive date&)

Formal ReportS. AUTHOR(S) (Lost name, first name, initial)

Murphy, Richard D., Brasseur, Gary W., Bart, Robert, and Williams, Robert M.6. REPORT DATE 7a . TOTAL NO. OF PAGES 7b. NO OF: REFS

November 1965 51 [vi] I _l80. CONTRACT OR GRANT NO. 9a . ORIGINATOR'S RCPORT NUMBER(S)

b. PROJECT NO. Report C-2106C. 9b OTHER REPORT NO(S) (Any other numbers that ma" be assithis report)d. Aero Report 10960o. V ILABILITY/LIMITATION NOTICES-In kdition to security r rements whic ly to this document and must be

each ansmittal e the Department of De st have priorthe Chie-, ureau of Naval Weapons (RAAD-3), Washington,

I. SUPPLEMENTARY NOTES 12. SPONSORING MILITARY ACTIVITYBureau of Naval WeaponsDepartment of the Navy_Washington, D. C. 20360

13. ABSTRACT

The results of preliminary vehicle design and mission-oriented operationsanalysis for predicted ASW systems are incorporated tc form an index of tacticacapability of an open-ocean seaplene. The vehicle is a canard configuration wfree-propeller propulsion on tilting lifting surfaces. Regenerative cycle turbprop engines power six 20-foot-diameter propellers to achieve VTOL capability aefficient cruise at 275 knots for the 93,000-pound VTOL or 125,000-pound STOLaircraft. Computer simulation of mission performance covering several thousandhours indicates favorable utilization of manpower and equipment. (C)

UNICLAtSSIFIED.

DD I JAN54 1473 3 .- assitication

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'0fi 1aFc~o 'fit____________14. LINK A LINK 8 LINK C

KEY WORDS ROLL: WT ROLE w ROLE

Seaplane DesignV/STOLTilt-Wing Free-PropellerCanard PlanformVertical FloatsASWPerformance PredictionComputer SimulationContact MaintenanceContact InvestigationTemporary BarrierATSSSSonobuoyA-New

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