RogerBW's Blog

Second Harpoon PBEM AAR: Non-Nuclear Nuclear Exchange 30 October 2014

I managed to get some players together for another Harpoon game, again played by email; it took nearly two months all told, though we did have several breaks of a day or two along the way. Here's the after-action report, as before plotted onto Tactical Pilotage Charts.

The scenario this time was Non-Nuclear Nuclear Exchange: in 1997, an Indian force based on Vikrant is sent to attack a flag-showing Royal Navy group based on an Invincible-class carrier. The RN is prohibited from firing until approached too closely, or fired on.

Indian setup

The Indians set up with the guided-missile destroyer Delhi in the lead, with three Veer (Tarantul I) missile boats nearby. Ranvijay, an Indian-modified Kashin II, and Vikrant, a converted WWII-era Majestic-class carrier, were strung out behind.

British setup

Meanwhile, to the south-east, the British were more spread out, with Manchester and Argyll out along the threat axis from the main formation; further towards the Indian group was a Sea King AEW helicopter, with a trio of Sea Harriers backing it up.

ESM detection

The Indians sent a pair of Sea Eagle-armed Harriers ahead to the south, and put up two Sea Kings also with Sea Eagles to search for the British fleet. As they climbed away, they got ESM hits from the British Sea King's Searchwater radar; they were spread out far enough that they got a reasonably accurate range too. Bizarrely, the Sea King AEW model (HAS.2) has no ESM receiver, and neither does that model of Sea Harrier, so the British were at first unaware of the Indians' presence.

(All remaining images are links to larger versions.)

Detection

Delhi went active with her 3D air search radar, and picked up the British Harriers backing up the Sea King. The Indian fleet started changing formation to protect Vikrant, and launching helicopters to move around, threaten attack, and cause confusion. Meanwhile the British Sea King went to air search mode, and immediately acquired two of the Indian helicopter groups.

The Indians' southern Harrier group turned in towards the British fleet, on the assumption that it would be somewhere behind the British air units. Without actually locating the British ships, the planes turned away just short of the 20-mile exclusion zone. The Indian helicopters climbed and advanced, bringing the British over their horizons.

By half an hour after scenario start, everyone pretty much knew where everyone else was, and the Indians continued to play tag with the twenty-mile limit.

Trespass

At 1715, the main Indian observation helicopter drifted too close to Argyll, around six metres inside the exclusion zone or an error of less than 0.02%. Of such moments is naval history made. The Indians (correctly) deduced that the British would fire on them, and all their helicopters launched Sea Eagles (mostly at Illustrious) before being shot down.

Both sides had Harriers, of course, but with slightly different equipment fits: the Indian air-to-air loadout was four Matra R.550s, short-range IR-homing missiles, while the British Harriers were also capable of carrying AMRAAMs. This made a big difference, as the British Harriers were able to knock the first four approaching Indians out of the sky from a safe distance.

One pair of Sea Eagles, while apparently on a bearing to Illustrious, had been aimed at Argyll on the leading edge of the formation. Argyll responded with Sea Wolf fire, knocking down both missiles four miles out.

The Indian Chetak, which had been providing surface position information after the Sea Kings were shot down, was knocked out by a pair of AMRAAMs, and the Indians were effectively blinded before getting off any of their shipboard missiles. They put up a Ka-25 Hormone off Ranvijay.

The fourteen Sea Eagle missiles aimed at Illustrious were whittled away by Sidewinders and AMRAAMs from the last Harrier to be in range and have any left, then by heavy Sea Wolf fire from Westminster which happened to be near the missiles' path and could engage them as they passed.

Missile seeker

Here relevant air defence envelopes are in blue, and missile seeker zones in red.

The remaining missiles were taken on by the fore and aft Goalkeepers aboard Illustrious, and the last survivor decoyed at the very last moment by ECM. Several ships had used up some of their countermissile stocks, particularly Westminster, but the British forces had weathered the helicopter-borne strike and were still undamaged.

Argyll and Westminster launched Harpoons at the cluster of missile boats, which by pure coincidence slowed down and changed course at the same moment. This didn't help, though.

The first group, from Argyll, were mostly shot down by Delhi's Shtil/Gadfly SAMs, but one survived to hit and sink Nirbhik. The group from Westminster arrived a few minutes later, again with three out of four knocked out by SAM fire, and the final missile went after Nishank, only to miss thanks to decoy launchers.

One of the Indian Harriers had moved round to the north, and entered a dogfight with the British Sea King that was still providing a surface radar picture, shooting it down – but then being knocked down in return by Sidewinder fire. The British Harriers still in flight headed for Illustrious to rearm, while Sheffield and Illustrious launched Sea Kings which headed for positions over Westminster and Manchester.

Those Sea Kings rapidly reestablished the British radar picture of the Indian formation, which moved in to close the range (the ships were still 60+ miles apart at this point, and most of their missiles would reach 45). The remaining Indian Harrier launched a pair of Sea Eagles at Illustrious: Manchester knocked them down with Sea Dart, then followed up by taking the Harrier, which had incautiously flown inside Manchester's air defence envelope while attempting to close with the British helicopters.

Delhi threw six Uran into the mix, with diverse waypoints to bring them at Manchester from different angles, but more Sea Dart and Sea Wolf fire took them down before they got close – though Manchester's Sea Dart magazine was down to four missiles.

A second salvo of the remaining ten missiles was more successful. They cut round to the south of the main formation (two attacking Argyll, shot down by Sea Wolf), whittled down by the last Sea Darts in Manchester's magazines, then went active.

Westminster was too small on radar to register, and by the time she did the more tempting target of Illustrious was also visible to the missiles. Final defensive fire sprayed fragments of one missile over the deck, destroying an armed Harrier and impairing the bridge; two missiles actually hit, damaging the hull but not knocking out any critical systems.

The remaining Harriers were sent out round to the north of the Indian formation, attacking Vikrant out of the north-east with Sea Eagles.

Some were shot down on the way in, both by long-range fire from Delhi and from Vikrant's own array of 40mm Bofors guns. But one missile got close enough to throw fragments into the ship, knocking out a Bofors and the longest-ranged radar, while the two that actually hit did significant structural damage, as well as knocking out the last Sea King in the hangar and thereby starting a major fire.

As the Harriers were heading back, the one out of the five that had been armed with AMRAAMs knocked down two of the remaining three Indian helicopters. The British ships turned south, and Argyll and Westminster fired their remaining Harpoons at Ranvijay.

This time they were more effective, with Delhi out of position as she was moving to lend assistance with firefighting aboard Vikrant. Delhi still knocked down one Harpoon, but Ranvijay's ageing SA-N-1s weren't able to cope with a modern, sea-skimming, low-radar-cross-section missile, and five Harpoons struck Ranvijay, sinking her.

The two surviving missile boats had cut to the south, and turned towards the British fleet, cutting the range to have a better chance of catching Illustrious in the seeker basket.

With the Harriers rearmed, three set out to hit Vikrant again, knocking down the last flying Indian helicopter in passing. This was the cue for the Indian missile boats to fire their Termit-M (SS-N-2C) missiles (which the British had believed to be part of the earlier multi-pronged attack). The two remaining Harriers scrambled to engage with Sidewinders, and Westminster flushed the remainder of her Sea Wolf magazine against them, but two survived to attack.

One hit Westminster herself, having somehow chosen the small ship rather than the big one out of the available targets, and crippled her comprehensively, starting multiple fires and floods. A shrapnel hit to a ready-use torpedo detonated it to complete the damage, leaving Westminster sinking but in reasonably good order, with most of her crew having time to abandon ship.

The other missile went into Illustrious, doing significant damage to the hangar deck and engineering; she was substantially reduced in speed, and two fires broke out, but she was not badly enough damaged to count as crippled.

The Harriers linked up some 25 miles south of Vikrant, and launched ten more Sea Eagles at her.

Delhi knocked down half of them with her remaining forward-firing SAMs, two were decoyed away, and one simply missed, but two struck home. Vikrant was heavily damaged and on fire, barely making six knots immediately after the strike, and dead in the water before the fires could be contained.

With assistance from other ships, the fires on both carriers were suppressed, but a follow-up strike to sink the immobile Vikrant was clearly on the cards while the Indians had nothing left to throw except SAMs, and we stopped the game at this point, on the assumption that Vikrant would be scuttled after her surving crew were taken off.

Although the Indians clearly got the worst of it (losing 20,135 tons of shipping, and all twenty aircraft, vs the British who lost 3,500 tons and five aircraft while retaining the ability to keep throwing anti-shipping strikes), there was no formal victory here for anyone: the Indians needed to cripple Illustrious and keep their own carrier afloat, while the British needed to keep Illustrious less than 25% damaged, and neither side achieved its goals. (Given the mismatch in capabilities, it makes sense for the scenario to be biased this way.)

Thanks to Tomasz (Blue) and Marco (Red) for playing. The moment-by-moment maps as shown to each player are available here. Things I've learned from running this game:

  • Yes, having real time is good, as I'd suspected it would be. My orders/plotting system now runs on unixtime internally, and converts out to local time in the filenames (there is an obvious potential bug here if a scenario spans a summer to winter time transition, but having readable file names is worth it). I also have sun and moon rising and setting time calculations automated, though visual spotting wasn't hugely important anyway except for damage evaluation.

  • Aircraft fuel calculations are best left to the computer. So I do. I have a "fuel" and "consumption" (kg per nm) entry for each air unit, change the "throttle" (consumption multiplier) level whenever it changes throttle setting, load state or altitude, and let the software take care of the details.

  • I'm also now automating radar horizon calculations, having extended my range table generator to work out horizon distances (which also gives ESM detection status). I'm still checking whether a unit is within another's detection range by hand, though, because dash it all I am moderating these games, not just playing computer-Harpoon.

  • That automation would actually make it very easy to do a "true horizon" calculation for each pair of units, rather than just using altitude bands. But would this lead to gamesmanship, putting helicopters up at 2000m to get a 99-nautical-mile radar horizon while still taking advantage of the "Low" altitude band fuel consumption for a turboshaft engine? Or is that a legitimate tactic?

  • I definitely need to refine the plotting of enemy units, to do things like drawing bearing-only plots on the chart automatically. Which means a matrix of detections: A has a full position fix on X and bearing-only on Y, B has bearing-only on Y and Z, etc., and the areas for bearing-only detections are plotted automatically.

  • During the game, I switched to assigning random unit identifiers to newly-detected enemy units, and allowing the detecting player to change them at will. That way the enemy can't spot units XXA, XXC and XXD and work out that there's probably an XXB out there somewhere.

  • I derived an formula for the time delay before you activate a seeker Time=Range*(1-Tspeed/(sin(Angle)*Mspeed))/Mspeed, so that no matter how the target evades after you've launched the missile he won't get out of the near sides of the acquisition cone. The time goes up with range to target, obviously enough, down with smaller seeker angle (you have to activate sooner to catch the whole target circle), and down with increasing potential target speed (the bigger the area he can be in, the sooner you need to start looking). It also goes down with increasing missile speed in a non-linear relationship (a fast missile arrives sooner, but the target area is smaller so it can activate a little later than that alone would indicate).

  • This scenario probably starts the forces too close together. If the scouting air units had been placed at higher altitudes, we could have had mutual detections on the first turn. To me, post-WWII naval combat should be about finding the enemy at least as much as shooting at him. All right, it is an example scenario.

  • When playing, I must always read my unit notes carefully. I'd expect an AEW Sea King to have decent ESM, but apparently not; it's a fairly old aircraft. The HAS.6 model does, but Blue similarly didn't notice this and used the AEW version for his first scout.

  • And I must read the enemy unit notes too! The Harriers look fairly evenly matched, until you notice that one side has access to AMRAAMs with their forty-mile range and the other doesn't.

  • The number of missiles is really important when you're going after capital ships. Both sides tended to send two missiles here, four missiles there, but fleet defences (mostly from Manchester and Delhi until the SAMs ran out) were good enough to make these a relatively minor hazard. If either had put up a more concerted volley, perhaps from different platforms and launched at different times but arriving at the target around the same time, things might have ended sooner. Waypoints are good for evading air defence ships, but really you want all the missiles to attack the target from about the same angle, so that defences have to split limited director channels and weapons between them.

  • As a more general rule, if it's worth firing one of your missiles, it's probably worth firing all of them (unless you're worried about wasting excess damage on a target that's already been sunk). Conversely, if it's not worth firing all of them, it's probably not worth firing one. Massed firepower to swamp defences is absolutely the way to go.

  • Having a tight formation forces terminal-homing missiles to choose from a wider range of targets (if Westminster hadn't happened to be in the basket, both of those Termit-Ms would have gone for Illustrious, scoring a crippling hit and potentially a tactical victory to the Indians right then), and helps mesh air defences of multiple ships. And the better radar coverage of a loose formation can be duplicated somewhat by helicopters.

  • When missiles start flying, ships are effectively stationary. They can manoeuvre a little (for example Delhi crossed barely into range to shoot at the first Sea Eagle strike on Vikrant) but if one were playing this out on a table it would be a valid approximation simply to freeze all ships in place while missiles are on the board. (Indeed, this is pretty much what the game Shipwreck! does.)

  • I wouldn't mind playing this one some time.

  • Next time I run a game I will do up full data cards for the aircraft as well as for the ships, from the beginning. It takes a little while, but it's just so much less hassle to have radar ranges and missile speeds and ranges ready for my use rather than going and checking a data annexe (possibly several different ones, including the Smarter Radars document) each time. In the long term I will get software working to produce the damn' things off a master platform database, but that'll take a while.

  • And I still haven't had enough, and want to do some more. Anyone who sees this and fancies a game, give me a shout with the sort of thing you'd like to play, and I'll sort out opponents and scenarios.


  1. Posted by Todd Jahnke at 11:59pm on 30 October 2014

    I am impressed and salivating at the prospect of playing, preferably in something "low tech" and "low density," or perhaps as part of a team in a middle-sized event.

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