Talk:Limbo (weapon)

Metadyne drive
The Limbo ships had a Metadyne room. In the Rothesay class this was between the two mortar magazines on 3 Deck. Photos from HMS Plymouth after modernization show just the one set remaining. I am under the impression the Metadyne amplifiers should have looked like big DC motor / generators, but can't see anything fitting that description in those photos, just rack and panel mounted equipment.

Metadyne is basically a DC amplifier. A DC constant speed motor drives a DC generator (or two or three) on the same shaft. The signal to be amplified is applied as a current to the field of the generator(s), and so the output is greatly amplified from the armature of the generators. Because the current can be reversed through the controlling field, the output will also be reversed. Thus perfect for controlling large reversible DC motors.

This type of control circuit was used in the E4 auto-pilot used in C-130 aircraft for many years, although the flight surfaces weren't moved directly by electric motors, but they acted as hydraulic servos. They weren't referred to as Metadynes, rather as channel amplifiers I believe.

The whole arrangement would have included range and bearing for the target, corrected for roll and pitch of the ship, therefore some sort of analogue computer, similar to what they used in the C-130 auto-pilot. Valves and synchros. I only know this because about 10 years ago I rescued an old C-130 auto-pilot from the tip and a manual from the archives, and with much trepidation applied 115V 400Hz to it after the components had been on the shelf for many many years. It all worked perfectly. The aircraft system of course computed for roll and pitch as well, so probably not too dissimilar, if on a rather lighter scale. Only difference might be the Limbo mounting needed almost instant response to roll to keep the weapon on track, whereas the aircraft system was deliberately designed to give rather more gentle responses, depending on rate of roll, position of control surfaces, amount of roll etc...., doesn't pay to rip the wings off. — Preceding unsigned comment added by 103.115.234.1 (talk) 00:37, 20 July 2020 (UTC)

I suspect, though not sure, that the Limbo was moved directly by electric motors, as this was apparently the case with some large gun turrets. I recall one RN dreadnought or battlecruiser had been fitted with half hydraulic and half electric driven turrets as an experimental direct comparison. — Preceding unsigned comment added by 103.115.234.1 (talk) 00:28, 20 July 2020 (UTC)

Reloading
The method of reloading is not mentioned. I presume there was a magazine of 16 or 17 depth charges immediately below each barrel, and the mortar tubes needed to be moved perpendicular to the deck while loading took place. Can anyone please provide further information? FreeFlow99 (talk) 16:07, 6 February 2024 (UTC)

The depth charges
There is no information here about the depth charges (diameter and length), no picture, no information about the explosive used, how the depth setting could be changed just before firing, or by what means they were propelled. It would be really nice if this could be added by someone with the knowledge (and ideally know of references). FreeFlow99 (talk) 16:18, 6 February 2024 (UTC)