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Author Topic: On the other Sword....PT.428 scenario  (Read 2456 times)

Offline zen

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On the other Sword....PT.428 scenario
« on: February 12, 2016, 02:26:51 pm »
"My own view, which I made perfectly clear, was that Blue Water should go. While I recognised that PT.428 was highly ambitious from a technical point of view, it made more sense to spend such money as was available on a weapon system that had some ostensible military purpose rather than one which I thought had none".

Assuming Solly Zuckerman was listened to, and Pt.428 is funded instead of Blue Water, and contiues to be funded instead of opting to buy Mauler from the US.

Ergo not canceled in Dec 1961 in favour of Blue Water.
Not canceled in 1962 in favour of Mauler.
Mauler is relegated to research in Nov '63 and cancelled in Nov '65

Landbased system (air mobile) used two groups of nine rounds.

The naval option seems to be a quadruple launcher with either 56 or 58 rounds. Curiously, at this time Sea Dart also used a quadruple launcher, but at that point it was expected to be just 768lb.
Each basic round was expected to be 242lb, presumably the boosted version weighed much more.
Length 7.4ft, diameter 5", span of wings ?
Length with booster seems to be 11ft.

Presumably, like Rapier and Mauler this is a weapon limited in basic form to 8.7km range or about 4.7nm
What I don't know is what the boosted version's range would've been.
What I now know is such beam rider's are capable of upto 30nm range as Sea Slug mk II had, though I suspect we'd more be talking around 15nm for this system.

Assumably this would be fielded in place of Thunderbird II much as Rapier did.
What is interesting to ponder, would be if this also see's RN service succeeding Sea Cat and in place of Sea Wolf possibly.

designs of ships where looked at using Sea Mauler, in this alternative scenario, they would have the PT.428 system.

As a curious asside, the early effort was Vickers, rather than Stevenage. Their LAA system looks rather different and uses a larger missile, without any booster.and maybe a SARH guidance system. Possibly 9.5ft long and 6 to 7 inches diameter.
« Last Edit: February 13, 2016, 08:59:08 am by zen »

Offline zen

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Re: On the other Sword....PT.428 scenario
« Reply #1 on: February 15, 2017, 03:29:02 am »
So why was this thought capable of engaging supersonic aircraft at low level?
When generally beam riders were not felt to be up to this?
Well the standard configuration of a beam rider is a single dish system, with the dish performing target tracking and target indication (beaming).
Consequently unless the target is approaching such that the tracking of it and it's eventual location where the beam rider missile will intercept are very close to each other the divergence between the two would mean the tracker moving to follow the lateral and vertical movements (relative to the tracker) and thus the guidance would be the same.
This means the missile follows a 'catchup' path, always trying to keep inside the beam as the beam veers to follow the target, and that is of course the movement of the tracking dish.
So the missile has to fly 'further' and looses energy trying to follow the movements of the target.

Now if one separates the tracking and indication dishes, then we can point the indication beam at where the target is expected to be once the missile has covered the distance in x amount of time. The beam and thus the missile are not subject to direct movements of the tracker, but rather the movement of the predicted location of the target.
It's a primitive form of command guidance, and one that doesn't require true datalinks. but it does impose on the computer controlling the process to calculate a predicted target location based on it's course and speed.

Now I don't have good details of PT.428, but what I can see in BSP.4 is seperate tracking and 'gathering' dishes for the system along with it's search set and IFF interrogator. But I will add the two big dishes (roughly 3.5ft or so in diameter) do look different as if they are to do different tasks......

More thoughts.....what is the band the beamer is using?
Q-band would ensure for such size of dish quite a narrow beam, ideal for the job.
The older RN's Type 901 was I think X-band.
curiously the 9ft diameter dish was good for a narrow beam out to 70km (37.8nm).
Equally curiously the much newer Q-band (ka-band to be precise) system for BAMSE was good for 30km (16.4nm) and is much smaller diameter than the Pt.428's dishes. However that is the product of several decades of work in radar.....and might be a AESA.....

So it would be fairly reasonable to think if the tracking and beaming dishes are 3.5ft or so, it's going to be reasonable to track and engage out to 30km or more.

However....if might be the case the tracking is done in X-band...I-band perhaps, as used for Sea Wolf, which is like Rapier a sort of descendent of this earlier short range SAM.
But then while this might not produce such a narrow beam for a 3.5ft dish, it would be sufficient to pick up and track a target at much greater ranges....such as a Canberra at 110km (60nm) or more, which is the expected figure for a new 3ft AI set. So it's reasonable to think it could track smaller targets at less distances.
Though I'm unsure about I-band's performance with clutter in this period.

Clearly the search set likely S-band and the IFF to start with is at least the mk10.

More thinking....the RN looked at PT.428 and liked it, they might quibble over beam riding, and here's the crucial bit "it didn't have enough range".......rather brings me back to SIG-16 which was also rather short ranged.....
SIGS required what range? 20,000yards (10nm) at low level and 30,000yards (15nm) at high level?
Demanding targets for Sea Dart was rated at 21km (11.34nm or 22,967yards).
Minimum range was 4.1km (2.214nm)
Curious thought, would that minimum not also apply to SIG-16?
Back to topic.
One should presume that therefore PT.428's boosted range fell short of the desired figure.
Likely this is the basis for the scaled up system, some 2.5 times that of PT.428 and the switch to SARH.
Getting more sidetracked again I would guess that increase is felt in diameter from 5" to 12.5" to provide a large enough seeker dish.

Back to topic again.
However as a short range SAM system it clearly has bags of potential, both in terms of developing guidance and within the missile fusilage.
« Last Edit: February 15, 2017, 04:03:58 am by zen »

Offline pathology_doc

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Re: On the other Sword....PT.428 scenario
« Reply #2 on: April 16, 2017, 04:44:15 am »
True beam riding is when you have the missile climbing up the tracking beam of the illuminator/director emitter.

By the time you're using a separate dish to track the target, you are starting to transgress on the borders of command guidance. Because in that case you can get the fire control system to steer the missile on a proportional navigation course.

Offline zen

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Re: On the other Sword....PT.428 scenario
« Reply #3 on: April 17, 2017, 02:20:38 am »
Exactly.
The Beaming radar is guiding the missile to a predicted target location that over time gets closer to where the target is. Dependant on the time it takes the missile to close the gap.
A possible upshot of this is the intercepting missile reflection in the guidance Beam could give the system realtime data on the missile, assisting the calculation of how long it will take to get to the predicted target location.

Offline zen

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Re: On the other Sword....PT.428 scenario
« Reply #4 on: April 09, 2018, 04:11:56 am »
Assumptions

Full system is supposed to fit on a Bedford truck, so we can presume it's below 4tons with 18 missiles.

Lightweight version replaces Sea Cat for 5nm range. Tied in possibly with MRS3....lets call it MRS3*, this would be applied as an upgrade to the likes of the Leander Frigates.

Studies DS346 (single automatic launcher, full system and boosted version for 15nm range) and DS347 (manual loaded launcher and light system for 5nm range).

Studies  with light manual launcher and optical target tracking MCLOS (Army's verylightweight system). Applicable to Corvettes and down to minesweepers.

Type 19 concept tied up with debate between automatic 'light' system and MCLOS system.
Type 21 with MCLOS system.
Type 22 with 'light' automatic system and manual launchers.
Type 42 with heavy automatic system for boosted missiles.
Type 23 with VLS development
Type 43 with VLS

Multirole Type 80 series study with full system with 2 large MGR. one heavy automatic launcher for boosted missiles  (15nm range), and one light manual launcher (5nm).
Side study for anti-ship system using launcher and booster motor, complex loader system to swtich between missiles. Arguments for VLS gain favour to simplify and remove the launcher and magazine.

Successor program options.
'Digitial Tartar' style, SARH and missiles designed to fit existing launchers, boosted version replaced by a unitary missile.
Digitial Command Guidance system and VLS
High speed option to extend current system's range.
« Last Edit: April 15, 2018, 03:13:40 am by zen »