UNCLASSIFIEDAD NUMBERAD077449CLASSIFICATION CHANGESTO: unclassifiedFROM: confidentialLIMITATION CHANGESTO:Approved for public release, distributionunlimitedFROM:AUTHORITYNRL ltr. 7103/114, 23 Oct 96; NRL ltr.7103/114, 23 Oct 96THIS PAGE IS UNCLASSIFIED- .frmed erViCC Technical Information AgencyReproduced byDO(UM1ENT SERVICE CENTERKNIOTT BUILDING, DAYTON, 2, OHIOThis document is the property of the United StatesGovernment. It is furnished for the duration of the contract andshall be returned when no longer required, or uponrecall by ASTIA to the following address: 3Armed Services Technical Information Agency, Document Service Center,Knott Building, Dayton 2, Ohio.NOTICE: WHEN GOVERNMENT OR OTHER DRAWINGS, SPECIFICATIONS OR OTHER DATAMR USED FOR ANY PURPOSE OTHER THAN IN CONNECTION WITH A DEFINTELY RELATEDGOVERNMENT PROCUREMENT OPERATION, THE U. S. GOVERNMENT THEREBY INCURS .NO RESPONSIBILITY, NOR ANY OBLIGATION WHATSOEVER; AND THE FACT THAT THEGOVERNMENT MAY HAVE FORMULATED, FURNISHED, OR IN ANY WAY SUPPLIED THE -. 0SAM DRAWINGS, SPECIFICATIONS, OR OTHER DATA IS NOT TO BE REGARDED BYIMPLICATION OR OTHERWISE AS IN ANY MANNER LICENSING THE HOLDER OR ANY OTHERPERSON OR CORPORATION, OR CONVEYING ANY RIGHTS OR PERMISSION TO MANUFACTURE, .USE OR SELL ANY PATENTED INVETwION THAT MAY IN ANY WAY BE RELATED THERETO.CC FDENTIA.L-00 NRL Report 4642ONFIDENTIAL FCCopyNo.* Li WO-HELICOPTER ATTACK SYSTEM. rCONFIDENTIAL TITLE)cm CL. C. Ricalzone and C. A. MatthesSound DivisionAirborne Sonar Branch cc)Engineering Section)CT, 1 4195bi 1ToofMs U NAVAL RESEARCH LABORATORY%, Washinqgtn. D.C.CONFIDENTIAL DC ZCON FIDENTIALCONTkNTSAbstract . . . . . . . . . 5iProblem Status . . . . . . e. . . . . . i .Authorization .INTRODUCTICN . 1SYSTEM DESCRIPTION . . . . e.e. 2OPERATIONAL FIELD TESTS . . . 4Initial Flight Tests . e.e 4Second Field Tests . 4Third Operation . . . 7DISCUSSICN . . e. . e.o. aCONCLUSIcNS . e. .-. . . 9RECOAMMENDATICNS .1. 0BASIC SYSTE24S PARAM1ETEJS. e . e. . 11CON FIDEN TIAL-C i iL 4.CONFIDENTIALABSTRACTBecause of the development of the modern high speed submarine,capable of high submerged speeds and prolonged submergence, along with 4the great vulnerability of surface ASW vessels to submarine attack, it-became desirable to develop an antisubmarine attack system suitable fora vehicle which poisesses a high mobility and comparative Invulnerabilityto submarine attack. To meet this need the Naval Research Laboratory hasdeveloped and field-tested the NRL Two-Helicopter Attack Sonar System. %Continued field research and development has been conducted for thepast two years, in which new techniques were evolved and exploited.Results of these field tests have shown that this system is capable of:Excellent short range classification, presenting precise sonar Infor-mation for fire control equipment, accurate vectoring of a transpondercarrier to a target, a probable increase in hit percentages with bothactive and passive ASW weaponS, and it requires a minimum amount ofsonar operator training because of the pictorial presentation.PROBLEM STATUSThis report is a final summary report which Includes much of theinformation previously reported. Some of the techniques developedunder this problem are being considered for application under anotherproblem.AUTHORIZATICNRL Problem S05-08BuAer Problem EL-46001Project Nos. NR ,85-080 and NL 430-014-3Manuscript submitted September 12, 1955iiCCN FIDENT-ALCCa F IDDE TIALTWO-HELICOPTER ATTACK SYSTEMINTRODUCTIONBecause of the development of the modern high speed submarine,capable of high submerged speeds and prolonged submergence, along withthe great vulnerability of surface ASW vessels to submarine attack, itbecame desirable to develop an antisubmarine attack system suitable fora vehicle which possesses a high mobility and comparative invulnerabilityto submarine attack. The most desirable vehicle for this use is the ASWhelicopter. With this in mind, the Naval Research Laboratory has de-veloped and field tested the NRL Two-Helicopter Attack Sonar System.The major objective of this effort was the development of a systemwhich would yield more complete information about a sonar contact withaccuracies considerably higher than those available in fleet airbornesonar equipment and to develop the technique of underwater guidance tothe target of a transponder towed from a second helicopter. Field trialsof this system have shown its high location accuracy of the transponderwith respect to target, simple transponder vectoring procedure, goodtarget classificat