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By: - 24th March 2022 at 10:06 Permalink
MG firing solenoids?
By: - 3rd April 2022 at 10:43 Permalink
Hi Denys, as suggested by powerandpassion these are indeed MG firing solenoids, for the Browning .303 to be precise. See attached illustrations for more info.
This is the explanatory text that goes with the illustrations :
Q
Type "A" - When the coil is energised the armature and plunger are attracted toward the coil, and the plunger moving causes the contact to bridge two fixed contacts completing the circuit to the firing solenoids.
When the firing switch is opened the magnetic field of the solenoid collapses and the spring returns the plunger and contact, so breaking the circuit.
Type "B" - The action of this type is practically similar to the Type "A" except no armature is incorporated with the plunger and the contact arrangements differ.
UQ
Looks like the ones you have are the type "B".
Any chance of sharing a few more pics and giving some dimensions like the diameter of the magnet tube please?
Cheers,
Walter
By: - 3rd April 2022 at 10:52 Permalink
Hi again, the explanatory text in my above post relates to the Solenoid Switches, not the solenoids themselves!
This is the right bit of text :
Q
Firing Solenoids
Type "A" and "B". These are very similar and their action is as follows:
When the coil is energised the plunger is pulled down the magnet pole plate or core, and the ball end of the plunger oscillates the rear sear release lever which in turn raises the tappet. The tappet will engage the rear sear lever on the gun and in turn the rear sear releasing the breech block.
As there is no return spring in the unit the tappet remains up until the circuit is broken when the rear sear spring on the gun returns all the parts to their normal positions.
It is possible to operate the gun manually if required by lifting one end of the lever, forcing the tappet up and holding it in this position.
UQ
Cheers,
Walter
By: - 4th April 2022 at 02:38 Permalink - Edited 4th April 2022 at 02:40
That's great thanks guys.
Walter ours definitely are type B.
Now I am just left wondering what a/c they would have been used in out here in NZ. I had thought of the FN turrets in Sunderlands bu have read that they use a Palmer hydraulic firing mechanism. Likewise B&P turrets on our Hudsons.
Anyway here are three views of one of them that I busied myself on last week.
thanks again
By: - 4th April 2022 at 05:34 Permalink
Mosquito used them
By: - 5th April 2022 at 11:33 Permalink
Wow. Marvelous work, Denys.
By: - 11th April 2022 at 02:36 Permalink
Our Mosquito project team say that mossies did not use such beasts, citing AP2019E as below, thus powerandpassion do you have a contrary reference?
By: - 17th April 2022 at 11:02 Permalink
It has come to my attention that I may be wrong. I do, however, submit some photos of an electro pneumatic valve set up that I always lazily thought was Mosquito. Perhaps Beaufighter? Vampire?
By: - 18th April 2022 at 14:05 Permalink
Hi Denys, thanks for the extra pics, that unit cleaned up nicely!
As for usage, from what I found it could come either from a Boulton Paul turret or of a Bristol B 1 Mk V which was used and further developed on the DAP built Beauforts.
As per "The Second World War - Royal Air Force 1939-1945 - Armament Vol II" one of the monographs written by the Air Historical Branch in the immediate post war years, it was decided during 1938 that pneumatic fire control would be used on all fixed gun installations and the hydraulic system on hydraulic gun turrets. Boulton Paul turrets, being electro-hydraulic powered usedthe solenoid firing system.
As for Powerandpassion's 4-way electro-pneumatic valve, how about this:
On pneumatic firing units fitted to 20 mm Hispano guns : "This system was used successfully on the Spitfire and Hurricane installations, but on certain other aircraft, such as the Beaufighter, the pilot was so far from the guns that the length of air pipeline from the firing button to the sear release unit became excessive and gave rise to an appreciable time lag between pressing the firing button and the guns opening fire. To overcome this an electric/pneumatic firing control system was used in which the standard pneumatic units were used adjacent to the guns, but were controlled by a solenoid operated valve operated by the pilot. In other words, the actual firing of the guns was pneumatic, the connection between the pilot and the gun bays was electric. This system was used on all aircraft after the Spitfire and Hurricane."
Could it be one of those units?
Cheers,
Walter
By: - 18th April 2022 at 22:20 Permalink
Ah ha Walter I think we have nailed it now.
btw Was the "The Second World War - Royal Air Force 1939-1945 - Armament Vol II" overly large as I'd be very interested in what it has to say about B&P Type C turrets as I'm doing one for our Lockheed Hudson?
However back to the point, I've only known about the firing solenoids in the Type C from the two attached images. The first is a photo of the turret on display at YAM taken as part of a photo bomb by one of our guys over there on a family visit. The second is a drawing the guys of the B&P archive sent me in a folio of things they saw would help me working on the Type C.
The crucial thing is that those two match up as images of the solenoids but the missing piece was your initial reply to me which now clearly shows that what I was looking at in those two references were type A solenoids while in my hand I had type B.
Given all that I'm confident enough to say that the pair I have will justifiably find home in our Type C as it seems improbable that they came to NZ by any other means so they ended up in such quantity at our source
Thanks for solving that for us...and I'll happily dodge comment on the Mossie stuff apart from saying that I've seen the valve installation in the nose bay of our project.
cheers
By: - 21st April 2022 at 20:16 Permalink
Glad to've been of help Denys! The publication I was referring to is +500 pages and describes the development history of RAF armament. I don't think that the turret related content will be of much help in any restoration project but it's an interesting read nonetheless. Being quite a thick book scanning pages won't be easy but if you're interested I can always give it a try. Just PM me your e-mail address and I'll see what I can do for you.
If you google pics of Boulton Paul Defiant turrets (the "A" turret if I'm not mistaken you should be able to find some where you can actually see the solenoids).
Cheers,
Walter
Posts: 138
By: Denys Jones - 24th March 2022 at 01:58 - Edited 24th March 2022 at 01:58
This is another one of those "what's this" postings I'm sorry to say.
Here in NZ we recently came into possession of these items and we've drawn a blank so far.
They are as you see it, definitely British given the BA hardware.
After cleaning the solenoid ( assuming that) has just a simple 173 roughly stamped on the black painted end. The casting across the other end yields two stampings, one simple 152A2 and the other the letters WDH over the number 1 in a circle so presumably the inspector's stamp.
The lever arm shows 182/32 while the rusted plate has 152A1 and CEC over P again in a circle, though no traces of paint at all.
.On the pin that the lever arm pushes through the rusted piece remnants of a brass coil spring around the pin were found.
Thanks for any insights.