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JSB
Post subject: Re: Fisherless Royal NavyPosted: July 19th, 2015, 9:40 am
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Like the idea of an early ASROC/ASM ( or ASRT? :? ), my questions are,

- Can you make it both ASW and ASurfW ? I would just go for ASW and drop the size of the Torpedo (and make it only go deep to save on retune homing, ie an early ASROC) Just not sure that a torp will home on any fast surface ships well with WW2 tech, will it not lose any target that speeds up and runs ? (so you might as well just make it a small ASW only Torpedo ?)

- ASurfW at 1500m who are you fighting ? if 4.5" will not cut it if not then will you still be in a state to use RAP Ts ? (I just don't think a WW2 homing torpedo can hit a fast BB/CV/CA/CL and 4.5" will work fine v smaller targets, so just go for 3x2 4.5" or heavy TTs ?)

- Why not (apart from cool factor) go OTL with Limbo ? more of a development of Squid and less into the black art of homing torpedoes (and may well work better early on and in shallow water)
Quote:
my question is how far should the torpedo be airborne for before it enters the water and goes active
I would think at least 1500yards (you want to drop directly on top of the contact at maximum range to minimise swim distance as your homer acquiring the target will be the weak part of the chain)

IMO - I think it looks a bit overloaded, (and the arcs for 40mm are not great)
4x4.5", 4x40mm STAAG, 3x40mm Boffin, 1 x triple Squid, 3 x Triple 21" RAP

I would be boring and go with 4x4.5" (on bow, 'AB') 4x40mm (near stern raised 'X' side by side so nearly 360 arcs), 2x40mm (bridge wings), and then a mix of 1 or 2 of squid/limbo/RAPT (say 2 sets on rear 1/2 of ship), and maybe a set of heavy TT

It also to my mind looks more like a 45+ to 1950s design, maybe a alternative to Limbo using ex German rocket teams ?


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Hood
Post subject: Re: Fisherless Royal NavyPosted: July 19th, 2015, 10:17 am
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You need some form of homing torpedo too and that tech is just not ready at this time.

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Krakatoa
Post subject: Re: Fisherless Royal NavyPosted: July 19th, 2015, 10:57 am
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from Wiki:

From 1943 extract:
Though its period of operational service was brief, Falke was a proof of concept for the acoustic homing torpedo. Its introduction occurred only two months before the U.S. Navy achieved its initial combat success with the Mark 24 FIDO "mine." FIDO was not a mine, but a passive, acoustic-homing torpedo designed for use by long-range patrol aircraft. (It was designated a mine for security reasons.) The initial success with the Mark 24 occurred on 14 May 1943, when a PBY-5 from VP-84 sank U-640 with the new weapon. Most sources indicate that the Germans' first combat success with the Zaunkönig (GNAT) did not occur until September 1943. While the Allies became aware in September 1943 that the Germans had brought GNAT into operational service, it was not until the capture of U-505 in June 1944 that they obtained reliable data on the German homing torpedo.


The Mark 24 mine (also known as FIDO or Fido) was a US air-dropped passive acoustic homing anti-submarine torpedo used during the Second World War against German and Japanese submarines. It entered service in March 1943 and continued in service with the US Navy until 1948. Approximately 4,000 torpedoes were produced, sinking 37 and damaging a further 18 submarines out of a total of 204 fired. The torpedo was also supplied to the British and Canadian forces. The deceptive name of "Mark 24 Mine" was deliberately chosen for security purposes, to conceal the true nature of the weapon.


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Hood
Post subject: Re: Fisherless Royal NavyPosted: July 19th, 2015, 11:44 am
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True but... you're asking for a torpedo that is fired from a tube, subjected to g forces on acceleration then impacting the water and sinking to a depth where it comes alive and homes on the target. Electronics in this era are not that robust, not saying its impossible as the other examples are air dropped, but unless you parachute retard its going to be a harsh landing.

I've nothing against stand-off ASW weapons but I love the old-fashioned Limbo style set-up.

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Judah14
Post subject: Re: Fisherless Royal NavyPosted: July 19th, 2015, 12:39 pm
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I think making it parachute retarded is the way to go, as modern ship-launched torpedoes such as the MU90 Impact are.


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Krakatoa
Post subject: Re: Fisherless Royal NavyPosted: July 19th, 2015, 12:49 pm
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Unfortunately Limbo does not come into service until 1955. That would have answered the call for a longer ranged ASW weapon nicely. I was trying to find something that would bridge the gap between Squid and Limbo. With the Type XXI, there is too much time for the sub to escape between when it is contacted and when a weapon can be deployed against it. With Asdic deployed your escort is held to 10-15 knots, so it is going to take 4-5 minutes at least to get in range. Type XXI can speed burst at 20-25 knots and actually extend the range. The escort can never get to deploy its weapon. With the RAT torpedo travelling at 200-300mph, that 1000 odd yards is travelled in no time and gives the 'homing' mechanism a chance to deploy and with a 35-40 knot speed can comfortably overhaul a XXI.

I don't know whether 2 years is enough R&D time to surmount some of those problems we have all identified, and to be able to have a weapon to overcome the Type XXI problem.


JSB: for surface warfare action the torpedo is 'rocket assisted' out to a 1000+ yards then deploys as a normal torpedo for the next 10-15,000 yards, using the homing portion (acoustic) or magnetic or whatever to impact the target.


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JSB
Post subject: Re: Fisherless Royal NavyPosted: July 19th, 2015, 5:54 pm
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What I was trying to say (badly) was that WW2 homing torpedoes cant do ASurfW they are,

- ASW v a slow Uboat (Fido Range / Speed 4,000 yards (3,660 m) / 12 knots)

- Anti escort weapon that makes the escort go fast to outrun it (and as its going fast it cant look for the Uboat so it can escape)
(German T5 designed to home in on cavitation noise of around 24.5 kHz which was equivalent to propellers on an escort travelling at 10 to 18 knots)

So I don't think you can use it to hit a fast surface target (it cant hear its target and move fast at the same time) this makes it just a unguided torpedo lunched inaccurately by rocket will that really hit anything ? Why not just hit the ship with the rocket would be more accurate ?


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Krakatoa
Post subject: Re: Fisherless Royal NavyPosted: July 19th, 2015, 7:26 pm
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The 'homing' torpedo runs in passive/active modes. Once launched it runs a predetermined distance (by setting) where it then becomes 'active' searching for the target. It is not launched 'active' otherwise the nearest 'loud' noises would come from the launch point and the launching ship is likely to become the target. What I would like to see but do not know if it is possible is to have two 'active' elements, the normal acoustic element, searching for propeller cavitation and then a 'magnetic' element where a close large metallic object (like a ship) attracts the magnetic sensors. If operating on the magnetic sensor it could still operate at high speed. Then you get into degaussing coils and all sorts of other countermeasures.

Most of it is guesswork based on real weapons. But it is probably not possible in 1945. The other problem I can see for surface work is that the launch is going to have a considerable flash which sort of gives away that there is a torpedo launch taking place and the target is well aware of what is coming and can take appropriate evasion procedures.

In 1945 UK/US rocketry, I do not think they have a long enough range to enable an attack at 10-15,000 yards or more. It is not until the German workings are captured in mid 1945 that US/UK rocketry goes ahead in leaps and bounds producing weapons like Regulus and future weaponry. An air launched bomb or gun launched shell are still the distance weapon till the 1950's.


By the way JSB, I am not looking for reasons why it wont work - rather I have been asking for peoples help in trying to make it work. What is needed to make it work, then is it possible to produce those bits and pieces in 1945. Try to be constructive, not destructive.


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JSB
Post subject: Re: Fisherless Royal NavyPosted: July 19th, 2015, 9:11 pm
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Krakatoa wrote:
By the way JSB, I am not looking for reasons why it wont work - rather I have been asking for peoples help in trying to make it work. What is needed to make it work, then is it possible to produce those bits and pieces in 1945. Try to be constructive, not destructive.
Sorry if you think I'm being negative,
I would just have it as a rocket lunched Fido for ASW only, it would be just about ready for 1945 and should be a useful weapon.

I would have it as a single shot (luncher based on a gun mount or the URP with a reloading mechanism to slid on a new torpedo) here is my go at one to show what I think it might look like,(hope you don't mind me posting it in your thread for you)
[ img ]


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Krakatoa
Post subject: Re: Fisherless Royal NavyPosted: July 19th, 2015, 9:56 pm
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The piece on Fido in Wiki is interesting reading. The weapon being based on a reduced 21" torpedo for air launching. Which is why I created a surface launched full sized 21" torpedo with the same sort of homing mechanisms to be launched from a warship. I used a full sized 21" torpedo as I did not think the rocketry of the time had enough power to launch something like Fido close enough to the target to make it count. The other point is that Fido is only good against the type VII and IX subs which have a slow enough submerged speed for Fido to intercept it. The Type XXI's would just run away from Fido. Creating it for 1945 would also have it being in service 1945-55 till Limbo and other ASW weapons come into service. Once the Type XXI technology is put into service in the late 40's early 50's (By the Russians as being the NATO 'enemy') there needs to be something that can be used to reliably intercept and sink them.


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