I was talking about the final illumination phase - I know SPY1 can guide SM2's etc for most of the distance to the target but in the final moments of the engagement, one of the three target illuminators has to be pointed at the target and, for best effect, kept pointed at it til impact.
By "beam" I meant "from one direction" - fundamentally, a Burke's got three illuminators available, and from most directions other than head on, at least one of them is masked at any time, leaving you two to cover any given direction.
I know it's possible to time slice between targets and I'm certainly given the impression that the motors on the illuminators are pretty hefty bits of kit allowing for them to be trained quite rapidly, but it's still a bottleneck.
" One AN/SPY-1D has one transmitter that uses two phase shifting antennae faces which covers about 195 degrees of space around the ship, there is some overlap. But each Burke has two AN’SPY-1D’s"
Not following you - SPY1-D has one transmitter and can therefore scan on one face at a time. SPY1-D(V) can scan on two faces per transmitter.SPY1-A/B carries two transmitters, and scans one transmitter per face. As far as I understand it, the Burke carries one complete SPY-1D comprising the four panel faces and transmitter etc - not two?
Ian
I hope I don’t bore you guys with explaining how thing really work. Power management of array type radars is a very complicated thing because they do so many different things but they do them sequentially, with tradeoffs of RF power, beam shape, scan speed, scan type, dwell time, duty cycle, pulse-width, and even more. The general rule for all kinds of radars is a simple one, the configuration of factors that makes it easier to detect a target, will also mean that the information you receive from that target using that configuration gets directly less precise, as the odds of detecting a targets increases. The information you will have on a targets size, range, height, speed and tracking data (refresh rate) will be sacrificed so as to increase the chances of first detection (it is mainly a function of average power and time on target). That is why in the past it required specialized radars for these different functions. The fact that some of these parameters are reconfigurable on the fly within phase array type radars does not mean that there are not still tradeoffs but most problems within radar systems can be made much easier with the addition of more power and then even more power, there is never too much power until you start interfering with other systems on your own ship, which has been known to happen.
To tell the truth in my earlier post I was using the Ticonderoga class cruiser as my model and it did not even accrue to me that the Burke used only one transmitter like the AN/SPY-1F. I just assumed it was the same, which was stupid, sorry. This mistake I freely admit, but the illumination problem as you put it, is not however the bottle neck that you think it is. The missiles themselves cannot all be fired simultaneously and nether will their arrival at their targets occur simultaneously. When you see multiple firings in close proximity from a ship it is usually from different cell groups. There is a small but real time lag between missile launches from the same cell groups so that they do not interfere with each other. The powerful exhaust blast of one missile could knock over another missile just as it is leaving its cell if they are fired too closely together and when they are barley moving fast enough to overcome gravity they are not very flight stable. The reason that there are only three illuminators on the Burk is simply because they really don’t need any more (assuming that they are all working at the time that is).
The fire control component of the system the AN/SPG-62/63 is two radars, a tracking radar and an illumination radar working on different frequencies sharing the same antenna system. To get the maximum reflected energy off the target the CW illumination beam should be as small in diameter and as powerful as possible for several reasons beyond the obvious ones concerning ECM. One reason for it to be small is if two targets are flying in close formation and the beam is too large it will fall upon both targets together and if you task two different missiles, each to hit each target they will both home in on the largest returned RF signal. It has happened where both missile have hit the same target leaving the other target untouched. And when the first missile hits its target it thus makes it an even bigger reflector of RF energy which increases the odds that the second missile will also strike the debris. This has occurred more than once. The second reason is at the longer ranges the beam spreads out reducing the energy falling upon the target and thus reduces the amount of reflected energy the missile needs to homes in on thus affecting its ability to locate and track.
The process of the handoff from the acquisition radar to the final tracking and control radar is always a very tricky and difficult thing to do. In fact the greatest advantage of the Phase-array radar is not how many targets it can track at the same time but the high accuracy it gives to the fire control radar in the handoff. In older systems it might take considerable time for the tracking radar to first search out and then finally acquire the target and only after that could it then track the target accurately enough to develop a firing solution to fire a missile. Fire control radars only look at a tiny area of space at a time and if the target moves quickly enough and the refresh rate of the search radar is too slow or if it is too inaccurate, it might never acquire the target at all. The phase-array provides not only a much better handoff, giving the tracking radar an almost instantaneous lock on, but it provides accurate enough information to have a firing solution for the missiles long before it was ever possible before. In the old days if you had three fire control radars you could only have three missiles streams in flight at a time. Under this system you can have many more missiles launched and on their way to many different targets at different bearings all the same time.
When the target is inbound and close to the ship the handoff is good enough that the tracking radar does not even need to acquire the target to put the illumination beam on it but at long ranges it does need to because the SPY-1D is not that accurate at the long ranges for this task. Notice that in the DDG-1000 class where you have X-band and S-band phase- arrays radars working together there is no decanted fire control radar tracking radar as such.
The worst case and the hardest to defend is that of a single ship out and alone and without air support coming from a combined high/low radial attack. The single high component of the strike group, is used to locate the ship and then it vectors the others elements running down upon the deck which are perhaps flying supersonically. The low components of the strike package to their attack positions. The low components are radar and radio silent and cannot be detected while they are below the ship's radar horizon where the high component it not. The low components fly their attack run in a bandit train formation or in several formations. Multiple fighter bombers flying in a head to tail configuration so that when the aircraft finally do pop up over the ship's radar horizon the ship cannot evaluate the numbers in the strike package coming at them along the different threat axes. Is it one aircraft or ten? They can come from one bearing or they might come from several? Coming along from each barring, are they one or two or from another it might be six or eight. The following aircraft will be in the leads aircraft’s radar shadow and the others probably undetectable.
When the ship fires at the strike group only then do they split apart flying parallel but separate paths until they launch their weapons and then follow their weapons in to get within the minimum range of the ships missiles. Their guns alone could take out the ships masts and their sensors leaving them helpless to further attacks.
If you were say the Chinese would you be will to lose five or six jets to kill a Burke? It would seem to be a good trade.
