Mosquito trial - what is it being tested?

WATU said:

Mossie 4054 was one of three prototype PR1's. That nudges it towards being an illuminant maybe?

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I don't think so. The original spec and illustration ThomasP posted shows that this is clearly an aerial mine designed to intercept the wing of an aircraft and then detonate a charge.

In fact, I think we're getting somewhere. What you are looking at it a variant of the LAM mine. Note the definition of 'AD' according to the glossary provide on the jeversteamlaundry site -



A PR mosquito would make a perfectly useful testbed I'd guess. Especially if you wanted to test release from faster aircraft than Harrows or Wellingtons - and with potential utility as a lightweight defence against pursuit.

SplitRz said:

I don't think so. The original spec and illustration ThomasP posted shows that this is clearly an aerial mine designed to intercept the wing of an aircraft and then detonate a charge.

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Quite right, forgot about that post!

SplitRz said:

In fact, I think we're getting somewhere. What you are looking at it a variant of the LAM mine. Note the definition of 'AD' according to the glossary provide on the jeversteamlaundry site -

AAD​	Apparatus, Air Defence part of the Long Aerial Mine project in WWII.​

A PR mosquito would make a perfectly useful testbed I'd guess. Especially if you wanted to test release from faster aircraft than Harrows or Wellingtons - and with potential utility as a lightweight defence against pursuit.

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I think that collectively nails what it was. Was it of use on operations? Any evidence for that?

WATU said:

I think that collectively nails what it was. Was it of use on operations? Any evidence for that?

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I can't find any evidence so far that it was used operationally by any others than the Harrow squadron;

"Operation Mutton

Although not a balloon borne device, this was similar in that it involved the release of "Long Aerial Mines" also known as "Pandoras", into the path of oncoming German bombers by British aircraft. The concept here was to break up a formation of enemy bombers so that they flew in a much more random way making them more vulnerable to our fighters. This began in September 1940. Following much experimentation, the optimum configuration for the mine was determined.

The resulting weapon fitted into a cylindrical container 14in long and 7in in diameter, and weighed 141b. After release from the aircraft the obstacle deployed.

It comprised, from top to bottom: a supporting parachute, a length of shock-absorber cord, the cylindrical container, an AAD bomb, 2,000ft of piano wire and, at the bottom, a second furled parachute.

When an aircraft struck the piano wire the shock wave ran up the wire, causing a weak link to break, releasing the main supporting parachute and the cylindrical container. As the container fell away the bomb was armed and a small stabilising parachute connected to the weapon was released. Simultaneously, the shockwave travelled down the piano wire and caused the lower parachute to open. This took up a position behind the aircraft and pulled the bomb smartly down on the aircraft.

However, in autumn 1940 Fighter Command's most difficult problem became how to counter the night raider. The long-term answer was the Bristol Beaufighter, fitted with airborne interception (AI) radar, directed on to its prey by a ground-controlled interception (GCI) precision radar. But each of those systems was in an early state of development, and some time would elapse before they were available in quantity. In the meantime, anything even remotely likely to be effective against the night bombers was pressed into use, including the Long Aerial Mine. German bombers attacking at night did not fly in formation. Instead, they approached their targets at irregular intervals, following their radio beams. At night, the mines were to serve a different purpose than that originally proposed. Instead of being used to split up an enemy formation, a line of mines would serve as an "aircraft trap" to destroy bombers.

Somewhat obsolete Handley Page Harrow twin-engined bombers were used for aerial mine laying. The device was successful as in 1941 there were six German bombers destroyed by the Pandoras."

There are some hints that a Havoc squadron was being equipped with LAM in around '41.

That said, and despite the dismissive comments about the LAM which I've read, I can't help thinking that it could have been a devastating weapon in a different context. Part of its limitation was that it was used against German night bombers which were flying in streams rathe than in a concentrated formation. And the Germans were also flying aircraft in comparatively small numbers. That was always going to make dropping mines into their path a very hit and miss affair (see what I did there?!).

But what would the effect have been if the Germans had developed an equivalent and had dropped them en masse into an RAF bomber stream over a German city? Or perhaps in an even more concentrated context, against a concentrated daylight raid by B17s and B24s?

Another aspect limiting our research is that it seems a lot of information and records relating to LAM remained secret for a long time after the war, and may even now, be sat as yet unread by modern eyes in some dusty IWM of Hendon archive.

Six German bombers destroyed in what looks like a limited trial sounds like an outstanding outcome. So why not deploy it? I wonder how strong the evidence was for the losses? Six German bombers crashed on British soil with wire still wrapped round? As you say there must be more in the archives. It ought to lend itself to OR spatial modelling in use against streams or other formations. Definitely more suited to dense formations and the effect of causing them to alter course would be a challenge for pilots. Interesting that the primary aim was to break up formations. That would mean it would have to be very visible. Add a light at night? Lots of questions.

WATU said:

Six German bombers destroyed in what looks like a limited trial sounds like an outstanding outcome. So why not deploy it? I wonder how strong the evidence was for the losses? Six German bombers crashed on British soil with wire still wrapped round? As you say there must be more in the archives. It ought to lend itself to OR spatial modelling in use against streams or other formations. Definitely more suited to dense formations and the effect of causing them to alter course would be a challenge for pilots. Interesting that the primary aim was to break up formations. That would mean it would have to be very visible. Add a light at night? Lots of questions.

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I know - regarding the Harrow claims, thats the same conclusion I drew! Its a fantastic return for an experimental weapon deployed in a low performance aircraft and only in small numbers.

Perhaps the issue was that airborne RADAR was coming online at this time, and with aircraft with sufficient performance to deploy it, perhaps LAM was seen as superfluous - especially when large night-time Luftwaffe raids petered out in '41

And there would also be the prickly issue of all of the semi-armed LAMS that missed their targets. What happened to them? Did they explode on contact with the ground? Could they have hit an electricity pylon and wires and detonated? Would they lie in trees, hedges and on the ground in a potentially dangerous partially armed state?

The collateral damage point is fair but has to weighed against what six bombers might do. Surely the odd accident would be acceptable as a quid pro quo? Plus the ground was being (relatively) littered with unexploded ordnance so that concept would have been normal at the time and not the shock that it would be in the UK now.

I am not really convinced that radar would change things. Radar provides information that allows the defence to optimise its defences which could include fighters and LAM-equipped aircraft. If LAM was practical then a mix depending on circumstances would seem attractive. Especially if LAM could be deployed by relatively second line aircraft so that they were additional to the fighter effort.

WATU said:

The collateral damage point is fair but has to weighed against what six bombers might do. Surely the odd accident would be acceptable as a quid pro quo? Plus the ground was being (relatively) littered with unexploded ordnance so that concept would have been normal at the time and not the shock that it would be in the UK now.

I am not really convinced that radar would change things. Radar provides information that allows the defence to optimise its defences which could include fighters and LAM-equipped aircraft. If LAM was practical then a mix depending on circumstances would seem attractive. Especially if LAM could be deployed by relatively second line aircraft so that they were additional to the fighter effort.

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We only know for certain that the LAM wasn't deployed *despite* those results. Its an intriguing question as to why. This is my list of suppositions as to the probable reasons:

1. The end of The Blitz by 1941. That marked the end of massed Luftwaffe raids. But even then, German bombers weren't flying in formation and nothing in the numbers or concentrations that characterised later RAF night bombing or USAF strategic bombing by day. It seems to me that the LAM needs a mass of aircraft flying in a fairly predictable course and altitude to give an attacking aircraft a reasonable chance of laying its curtain of LAMs in front and above them at the correct altitude. Wind drift and any change of course or altitude is going to make that a challenge. After all, once you've dropped your LAMs, you're 'outta dough'. They're not a 'drib here, drab there' kind of weapon - they rely, like any minefield, in making a 'wall' in which their numbers ensure a hit. A cannon armed and radar equipped night fighter can be re-vectored. An empty LAM bomber is going to have to go home. But not only that, deploying the LAMs will also preclude any other friendly fighter from operating in that area. And in the days before capable airborne radar and all the known issues of navigating accurately at night, how are you even going to accurately define the area to avoid? The operational challenges are considerable.

2. One of the biggest headaches for home defence during the blitz were enemy unexploded ordinance - be it 'duds', timed explosives - or deliberate (and/or accidental) booby traps like the infamous butterfly bomb. These were responsible for a large number of people killed as a result of bombing. Adding to that tally by strewing the cities and countryside with unexploded LAMs wasn't likely to endear anyone to farmers, bomb disposal squads or civilians alike.

3. Radar in 1941 was nothing like the modern equivalent. Especially airborne radar, which often had a range under 5 miles even under ideal conditions. That was good enough to allow a tail-chase interception in conjunction with ground radar, but I think would be asking a lot for someone to identify an enemy, predict their course and altitude, fly ahead, calculate a release altitude, time and distance (whilst allowing for everything else!). If it was a massed formation of aircraft, maybe - but after '41, aircraft were only coming over individually or in handfuls. AI Radar operating in conjunction with ground control on the other had *was* just about good enough to give a cannon armed night fighter a reasonable chance of making an interception of an individual intruder - and even follow up attacks.

So I think its really ultimately a question of the target - massed bomber formations - simply ceasing to exist over the UK by '41. Had the Germans adopted the same tech for use against US bombers - especially in the period before the Mustangs got into business, I think they could have been devastating to be honest.

Its also possible that they would have been effective on the occasions that the Germans could identify the targets for massed RAF night raids. Even though a night bomber stream was no where near as concentrated as a daylight box formation, like you say, second line aircraft could simply 'sow the sky' with LAMs. That said however, it would create a massive 'no go' area for their own night fighters, which, lets face it, were highly effective in their own right. So I'm not sure that it would have won them an advantage overall.

Well-argued.
Lack of adequate mass targets makes sense and was likely the driving factor. Yet, as you say, that type of target should have made it very attractive to the Germans later on. I wonder if they tried a version? They would have been aware of Allied weapons of that style and they loved a gimmick.
I was a bit blase on the unexploded devices on friendly ground. Could be limited to over the sea but strong winds could still make that erratic. Wind generally would have been a limiting factor.
Radar - I was only thinking of ground-controlled rather than AI. A ground air defence control could allocate fighters or LAM aircraft subject to the nature and timing of the threat. Actually that counts against lower performance aircraft being used for LAM as their rate of climb wold be poor and they would need more time to get to a workable altitude.
I wonder why the Mossie PR prototype was used in the trial? That would not have gone near enemy formations and would have only been chased by individual interceptors. Dropping a device for a following fighter to run into sounds good but a cross wind would have made the probability of a hit low I feel.
I'll keep an eye open for wire mines generally. I don't think the ship rocket ones were well-regarded although as a pilot I would have expected they would be very unwelcome. Maybe one of those weapons that did not kill things but did degrade bombing accuracy by causing the bombers to manoeuvre making it hard to assess the value.

WATU said:

Well-argued.
Lack of adequate mass targets makes sense and was likely the driving factor. Yet, as you say, that type of target should have made it very attractive to the Germans later on. I wonder if they tried a version? They would have been aware of Allied weapons of that style and they loved a gimmick.
I was a bit blase on the unexploded devices on friendly ground. Could be limited to over the sea but strong winds could still make that erratic. Wind generally would have been a limiting factor.
Radar - I was only thinking of ground-controlled rather than AI. A ground air defence control could allocate fighters or LAM aircraft subject to the nature and timing of the threat. Actually that counts against lower performance aircraft being used for LAM as their rate of climb wold be poor and they would need more time to get to a workable altitude.
I wonder why the Mossie PR prototype was used in the trial? That would not have gone near enemy formations and would have only been chased by individual interceptors. Dropping a device for a following fighter to run into sounds good but a cross wind would have made the probability of a hit low I feel.
I'll keep an eye open for wire mines generally. I don't think the ship rocket ones were well-regarded although as a pilot I would have expected they would be very unwelcome. Maybe one of those weapons that did not kill things but did degrade bombing accuracy by causing the bombers to manoeuvre making it hard to assess the value.

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If you're interested in wired parachute mines, you might also be interested in the Z-Battery concept which was used operationally in the ground to air capacity - Z Battery - Wikipedia

I could get interested but I drifted into this while I was looking at bombsights. I ought to get back to them for now.

WATU said:

Hi
Just wondered if anyone knows what "A.D. Type H in Mosquito" refers to. It was a trial in June 1942. Is it just part of the fuel/oil trials or something additional? See attached for extract from UK National Archives file. Thanks

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My Dad would have met W4054 in Vaenga - Russia in early Sept 1942. I suspect his team would have been called in to at least pre- flight it for the return to UK. His team would have no specific knowledge/training on a new/secret type. They did have a PRU Spitfire operating on their field, tracking over the Tirpitz. Miserable quality image
Hamdemon