按键盘上方向键 ← 或 → 可快速上下翻页，按键盘上的 Enter 键可回到本书目录页，按键盘上方向键 ↑ 可回到本页顶部！
————未阅读完？加入书签已便下次继续阅读！
The frigate was steaming at twelve knots； and her Prairie/Masker systems were operating。 Sonar conditions were better today。 A hard thermocline layer at two hundred feet severely impeded the utility of a surface sonar。 Pharris was able to deploy her towed…array sonar below it； however； and the lower water temperature there made for an excellent sound channel。 Better still； the layer worked in both directions。 A submarine's sonar had as much trouble penetrating the thermocline as a surface sonar。 Pharris would be virtually undetectable to a submarine below the layer。
〃How's the plot look？〃 the tactical action officer asked。
〃Firming up；〃 ASW answered。 〃Still the distance question。 Given the water conditions and our known sonar performance； our sonar figure of merit gives us a contact distance of anything from five to fourteen miles on direct path； or into the first convergence zone。 That predicts out from nineteen to twenty…three miles 。 。 。〃 A convergence zone is a trick of physics。 Sound traveling in water radiates in all directions。 Noise that traveled down was gradually turned by water temperature and pressure into a series of curves； rising to the surface； then bending again downward。 While the frigate could hear noise out from herself for a distance of about fourteen nautical miles； the convergence zone was in the shape of an annulus…the area between two concentric circles…a donut…shaped piece of water that began nineteen miles and ended twenty…three miles away。 The distance to the submarine was unknown； but was probably less than twenty…three miles。 That was already too close。 The submarine could attack them or the convoy they guarded with torpedoes； or with surface…to…surface missiles； a technology pioneered by the Soviets。
〃Remendation； gentlemen？〃 Morris asked。 The TAO spoke first。
〃Let's put the helicopter up for the near solution； and get an Orion working the far one。〃
〃Sounds good；〃 ASW agreed。
Within five minutes； the frigate's helo was five miles out； dropping Lofar…type sonobuoys。 On striking the water； these miniature passive sonar sets deployed a non…directional sonar transducer at a preselected depth。 In this case all dipped above the thermocline layer to determine if the target was close。 The data was relayed back to Pharris's bat information center： nothing。 The passive sonar track； however； still showed a submarine or something that sounded like a submarine。 The helo began moving outward； dropping sonobuoys as it went。
Then the Orion arrived。 The four…engine aircraft swooped low along the frigate's reported bearing…to…target。 The Orion carried over fifty sonobuoys； and was soon dropping them in sets both above and below the layer。
〃I got a weak signal on number six and a medium on number five；〃 a sonar operator reported。 Excitement crept into his voice。
〃Roger； confirm that；〃 the tactical coordinator on Bluebird…Three agreed。 He'd been in the ASW game for six years； but he was getting excited； too。 〃We're going to start making MAD runs。〃
〃You want our helo to back you up？〃
〃Roger that； yes； but tell him to keep low。〃
Seconds later the frigate's SH…2F Sea Sprite helicopter sped off north； her magnetic anomaly detector trailing out by cable from a shroud on the right side of the aircraft。 Essentially a highly sensitive magnetometer； it could detect the disturbance in the earth's magnetic field made by a large chunk of ferrous metal…like the steel hull of a submarine。
〃Signal on number six is now medium…strength。 Signal on seven remains medium。〃 The plotting team took this to mean that the submarine was heading south。
〃I can give you a working range figure；〃 ASW said to the TAO。 Forty…two to forty…five thousand yards； bearing three…four…zero to three…three…six。〃 The frigate relayed this at once to the Orion。
As they watched on radar； the P…3C quartered the area； flying very precise tracks across the box of ocean defined by Pharris's sonar data as the probable location of the submarine。 A puter system plotted the lines as they extended to the south。
〃Pharris； this is Bluebird。 Our data indicates no friendly subs in the area。 Please confirm； over。〃
〃Roger that； Bluebird。 We confirm no reports of friendlies in the area。〃 Morris had checked that himself half an hour before。
〃Signal strength increasing on number six。 We now have a weak signal on number five。 Number seven is fading out。〃 The technician was really struggling to be professionally impassive now。
〃Range is firming up。 Estimate target speed roughly eight knots； distance forty…three thousand yards。〃
〃Transient！ Transient！〃 called the ship sonar operator。 A metallic noise had e from the target bearing。 A closing hatch； a dropped tool； an opening torpedo tube door…something had made a uniquely man…made sound。
〃Confirm mechanical transient； copied on buoys five and six；〃 the aircraft called immediately。
〃Confirmed；〃 Pharris's TAO answered。 〃We got that on the towed array； too。 We evaluate the contact as positive submarine at this time。〃
〃Concur；〃 the Orion replied。 〃Positive Redboat classification…madman！ Madman； madman； smoke away！ We have a NLAD contact。〃 A big spike appeared on the MAD readout。 Instantly； a crewman flipped a switch to deploy a smoke marker and the aircraft turned hard right to circle back on the contact point。
〃Plotted！〃 The tactical action officer marked the position on his tactical display scope with a large V symbol。
The helo raced in on the contact as the Orion circled back。
〃Madman！〃 its systems operator called out； and the helo dropped its own smoke bomb； slightly south and west of the Orion's。
The data was now being relayed to the frigate's torpedo…tube and ASROC attack directors。 Neither had anything like the range to engage the target； but that could change quickly。
〃Patience；〃 Morris breathed from his chair in the CIC； then louder： 〃Take your time； people。 Let's lock this guy in before we fire。〃
The Orion's tactical coordinator agreed； forcing himself to relax and take the time needed。 The P…3 and the helicopter made another MAD run north to south。 This time the Orion got a reading and the helo did not。 Another run； and both had the contact's course line。 Next came an east…to…west run。 At first； both missed； but on the second run both had him。 The contact was no longer an it。 Now it was a he； a submarine being driven by a man。 Control of the operation now passed exclusively to the tactical coordinator on the Orion。 The big patrol aircraft orbited two miles away as the helicopter lined up for the final pass。 The pilot made a very careful check of his tactical display； then locked his eyes on the gyropass。
The helo began the last MAD run； with the Orion two miles behind it。
〃Madman； madman； smoke away！〃 The final smoke marker dropped； a green flare floating on the surface。 The Sea Sprite banked hard to the right to clear the area as the Orion came in low。 The pilot watched the smoke's movement to figure wind drift as he lined up on the target。 The P…3C's bomb bay doors opened。 A single Mk…46 ASW torpedo was armed for launch。
〃Torp away！〃
The torpedo dropped cleanly； its braking parachute trailed out of the tail to make sure the weapon entered the water nose down。 The Orion also dropped an additional sonobuoy； this time a directional DIFAR。
〃Strong signal； bearing one…seven…niner。〃
The torpedo dove to two hundred feet before beginning its circular search。 Its high…frequency sonar came on as it reached search depth。 Things started happening quickly。
The submarine had been oblivious to the activity over her head。 She was an old Foxtrot。 Too old and too noisy for front…line operations； she was there nonetheless； hoping to catch up with the convoy reported to her south。 Her sonar operator had noted and reported a possible overhead splash； but the captain was busy plotting the position of the convoy he had been ordered to approach。 The torpedo's homing sonar changed that。 Instantly； the Foxtrot went to flank speed； turning hard to the left in a pre…planned evasion maneuver。 The suddenly increased noise of her cavitating screws was discernible to several sonobuoys and Pharris's tactical sonar。
The torpedo was in ping…and…listen mode； using both active and passive sonar to find its target。 As it pleted its first circle； the passive receptors in the nose heard the cavitation noises of the submarine and homed in on them。 Soon the active sonar pings were reflecting off the submarine's stem as it dodged left and right trying to get away。 The torpedo automatically went to continuous pinging； increasing to maximum speed as it homed in on its target like the remorseless robot it was。
The sonar operators on the aircraft and the frigate had the best picture of what was happening。 As they watched； the bearing lines of the submarine and torpedo began to converge。 At fifteen knots； the Foxtrot was too slow to run away from the forty…knot torpedo。 The submarine began a radical series of turns with the torpedo in pursuit。 The Mk…46 missed its first attempt for a kill by twenty feet； and immediately turned for another try。 Then the submarine's captain made a mistake。 Instead of continuing his left turn； he reversed it； hoping to confuse the oning torpedo。 He ran directly into its path 。 。 。
Immediately overhead； the helicopte