How would the Oerlikon GDF...

If it helps I understand that the Hoods Type 284 Gunner radar could track the Bismarks 15in shells

The problem is the theoretically available and the practically available. Not to mention the practicality of fitting such a system on board a ship using WW II technology.
Drawing of the below decks part of the fire control system described in Post #12 once you started fitting radar.


This has nowhere near the capabilities (or the weight/volume) requirements of a CIWS type system using WW II technology.

The modern CIWS that started this just needs some clear deck space to bolt it to, a decent amount of sky arc to fire into (to reduce the need for multiple mounts and from the ship.
"The only inputs required for operation are 440 V AC three-phase electric power at 60 Hz and water (for electronics cooling). For full operation, including some nonessential functions, it also has inputs for ship's true compass heading and 115 V AC for the PASS subsystem. "

A WW II version is going to need large amounts of power, dedicated rooms full of vacuum tube (valve) equipement and a slew of technicians to look after it. It is going to need one or more radar antennas, plus the actual gun mount it self and a high speed, stabilized mounting is going to be a very heavy item indeed.

Post war twin 40mm STAAG mounting on HMS Diana. some of the STAAG mounts went 17.5 tons.

The US quad mount went about 11-12 tons. manually operated single 40mm guns went about 1 1/4 to 1 1/2 tons.

You are going to need a vastly improved level of accuracy to make up for the weight and volume, assuming you can A) get the thing to work, B) keep it working after weeks at sea.

Glider said:

If it helps I understand that the Hoods Type 284 Gunner radar could track the Bismarks 15in shells

Click to expand...

Probably PoW because Hood

Glider said:

If it helps I understand that the Hoods Type 284 Gunner radar could track the Bismarks 15in shells

Click to expand...

If the rounds were about 1/2 wavelength in dimensions they would tend to show up very well. A 40mm shell would probably work very well with 9cm, 3cm and the 2.5cm and even 1.5cm radar that was showing up. A corner reflector, or something similar, or half wave reflector could probably be integrated to make the shell show up even stronger.

I know that Bismarck had a muzzle velocity measurement system on the main guns.

I know that the German FuMO 23 radar aboard Bismarck like the British 284 aboard PoW and Hood could detect shell splash and that this was used to correct aim. In fact the range limit to naval radar direct blind fire was considered the range at which the shell splash could be spotted rather than the range at which the radar could detect reliably.

I dont know if anyone attempted to make use of this ability to track shells either to correct their own aim or provide some warning. During the V2 campaign the head of AAA over Britain wanted money to develop radars to shoot at V2 missiles.

Shortround6 said:

The problem is the theoretically available and the practically available. Not to mention the practicality of fitting such a system on board a ship using WW II technology.
Drawing of the below decks part of the fire control system described in Post #12 once you started fitting radar.
View attachment 575537

This has nowhere near the capabilities (or the weight/volume) requirements of a CIWS type system using WW II technology.

The modern CIWS that started this just needs some clear deck space to bolt it to, a decent amount of sky arc to fire into (to reduce the need for multiple mounts and from the ship.
"The only inputs required for operation are 440 V AC three-phase electric power at 60 Hz and water (for electronics cooling). For full operation, including some nonessential functions, it also has inputs for ship's true compass heading and 115 V AC for the PASS subsystem. "

A WW II version is going to need large amounts of power, dedicated rooms full of vacuum tube (valve) equipement and a slew of technicians to look after it. It is going to need one or more radar antennas, plus the actual gun mount it self and a high speed, stabilized mounting is going to be a very heavy item indeed.
View attachment 575538
Post war twin 40mm STAAG mounting on HMS Diana. some of the STAAG mounts went 17.5 tons.

The US quad mount went about 11-12 tons. manually operated single 40mm guns went about 1 1/4 to 1 1/2 tons.

You are going to need a vastly improved level of accuracy to make up for the weight and volume, assuming you can A) get the thing to work, B) keep it working after weeks at sea.

Click to expand...

I don't disagree about the challenges but if the resources were put into it was possible and might have paid of more than the various remote control drone and BAT radar guided glide bombs the US worked on. The USA achieved deployment of auto track on the SCR-584 and BAT missile, The Germans on FuMG 64 (range gate only) though they could have simply passed the deviation signals to servo motors.

Looking at that installation closing the feed back loop would require:
1 A module to exclusively track the shell either using a special frequency optimised to pick up the shell only or to a point about 25 meters ahead of the target before the return pulse merged with the target or using pulse to pulse doppler to filter our all targets except the shell. That could be done with acoustic delay lines as 'memories'. I think tracking the shell to within 25-50 meters ahead of the target would be enough. The deviation signals produced by conical scan are linear within a few degrees of the centre of the scan.

2 A module to correct the aim and sum it in.

It might even allow the wind correction to be removed since tracking the round already incorporates wind correction.

The German guided weapons Fritz-X and Hs 293 were primarily defeated by allied escort carriers and air power. However these weapons were coming back on the jet aircraft and with new guidance systems such as the Tonne-Seedorf TV guidance, MAX-P (centimetric passive homing), infrared guidance, jet fighter with toss bombing sights. There was even a supersonic anti shipping missile 'zitterroechen" (stingray)

Although the Boffors round has excellent ballistics, its firing rate was a little slow at 120-140 rpm. The Germans had a 3.7cm FLAK 37 which had a shorter range but a slightly higher firing rate than the boffors, 160RPM. Despite better range they didn't use it much since the firing rate, range and weight didn't really create a compelling reason ie pK , using the 2.0cm FLAK C38 in a quad mount in much larger numbers.

However by 1942/43 they moved to a gas operated mechanism instead of recoil which increased firing rate to 250. That would be better. I think a single barel creates less alignment issues and a high rate of fire is needed to correct the aim by sampling often enough.