A better Coastal Command?

I should clarify that the survey of Coastal Command operations focused on merchant vessels not submarines, and economic warfare against the shipping routes of high grade iron ore going from Scandinavia to Germany.

Aerial mine-laying could be done at night, with a much lower risk to aircraft and crew. And it was not necessary to use high-performance machinery for this sort of tasking.

While mining was very useful/productive it had to wait for both suitable mines to be developed and the aircraft to carry them.

Most of the mines dropped from aircraft By the British in WW II being of 1000lbs weight or more and due to their bulk often needed larger size bomb carriers. The ground mines MK I, II, III, and versions of them going around 1500lbs or better and originally designed to fit the dropping gearof the MK XI 18 in torpedo. The MK III** was dropped from Mosquitoes but was hung from the 4000lb bomb gear.

There was a 1000lb air dropped moored mine but it was little used, minimum depth was 60ft and with a 100lb charge it may not have been very effective against large ships.
There were some very small mines for rivers and estuaries. Most of theses seem to have been built during 1940. Possibly for use against operation Sea Lion?

CC had a rather distinct lack of aircraft in 1939-40 capable of carrying a 1000lb store let alone a 1500lb one.
only choice was the Vildebeest and perhaps the Sunderland.

Sunderland could carry the weight but the bomb racks retracted into the fuselage and the size of the hatch could restrict the size of the stores used.
Short range mining operation might be done with racks outside but loading the racks might be difficult and take-offs might require calm seas.

The first order for 30 aircraft dropped, trial, magnetic mines was placed by the Admiralty in July 1939, just two months before the outbreak of war.

What the trials showed was that neither the Beaufort, ear marked as a mine layer by Coastal Command, nor the Fleet Air Arm's Swordfish and Albacores had the range to reach ANY of the areas selected for mine laying.
This was the reason that it was decided to give the Hampden a mine laying capability. The mine needed extensive modification due to the increased speed and height from which the Hampden would drop the device. A nose fairing and a drogue parachute were fitted.

The trial program ended in March 1940 and production models of the modified mine, designated A Mk I became available in April 1940. It weighed a nominal 1,500 lbs.

The first British aerial mine laying operation of the war took place on 13/14 April 1940 when Hampden's of 5 Group Bomber Command laid 14 mines off the Danish coast. The Luftwaffe had eaten the RAF by five months.

By June the Germans occupied 1,600 miles of coast and inland waterways stretching from Northern Norway down to the Franco-Spanish border. Now there were areas within range of Coastal Command aircraft would mine relatively close to home, Bomber Command in the western Baltic, Kattegat, the Great and Little Belts, Kiel Bay and the approaches to the Elbe.

The saga of the anti submarine bomb!
There were three anti-submarine (AS) bombs available at the beginning of the war, 100lb, 250lb and 500lb. By 1940 all were Mk IVs, with a solid nose and clip on tail. The solid nose and deletion of the nose fuse was because in 1934 trials the nose fuse was shown to effect the underwater trajectory of the bomb in an unpredictable fashion. The design was of 1926 vintage. No trials were undertaken to determine the thickness of case needed to withstand impact with the water, it was arbitrarily decided to have a charge to weight ratio a little over 50%. They were very unreliable, suffering a 40% failure rate (in the No. 30 tail pistol) in trials, largely due to difficulty in guaranteeing detonation at a depth of 20-25 feet, that considered optimal for attacking a surfaced submarine.
These bombs were not completely ineffective, but the failures did far outweigh the successes. In 1939 Coastal Command aircraft spotted 57 U boats, attacked 40, but damaged only 8. Nonetheless, in the early days;
Two 100lb AS bombs, dropped from a Swordfish, sank U-64 in Herjangs Fjord (near Narvik) on 13th April 1940
U-55 and U-26 were both sunk or 'encouraged to scuttle' with the help of 250lb and 100lb AS bombs dropped by Sunderlands of Nos 228 and 10 Squadrons respectively, in January and July 1940.
U-46 was seriously damaged by four 100lb bombs whilst in Norwegian waters in November 1940.

Eventually, given the shortcomings of the AS range of bombs, they were replaced by air dropped depth charges, starting with an adapted version of the 300lb naval Mk VII depth charge. The first live one was dropped from a Sunderland, off the Isle of Wight, in April 1940. Many improvements and different versions followed, but not here!

Cheers

Steve

Nice info Stona. Do you know how the No30 fuse worked I always assumed the Anti Sub bombs were impact fused but obviously if they were expected to explode at 25 feet thats not the case. Was it a delay fuse activated by the deceleration when the bomb hit the water.

Thank you!

Effective as mines turned out to be the situation in 1935-39 was not conducive to a mine strategy. Without hindsight the distances needed to be flown to place mines in German waters would have to be flown by medium bombers. Once the Germans took Belgium, Holland and France distances were much shorter but this could not be foreseen in the late 30s.
It was just over 300 miles from Hull to Emden and a slight dog leg is needed to avoid flying over Dutch Airspace.

Moored mines are not very efficient from an air drop point of view. You are lugging hundreds of pounds of anchor/mooring point and steel cable for each package of explosive and moored mines tend to often be too deep to be effective or too shallow which exposes them at low tide.

The early battles with the Uboats occurred within about 100 miles of the British coastline, so the need for a long range aircraft was not necessary in the early stages. There were glaring weaknesses in the make up of CC that needed to be addressed before anything useful could be accomplished. these included

• Re-learning basic patrol procedures, to provide scouting capabilities for convoys so that they could be re-routed to avoid wolfpacks.
• Development of an effective airborne ASW weapon
• Development of functioning ASV radar
• numbers, numbers, numbers
• Types were adequate at the beginning of the war, and were able to drive the uboats away from the coastal areas within 6 months, along with a veritable armada of light forces. but the Uboats with constantly increasing operational ranges and the capture of French Atlantic ports, simply moved to their favourite klling area, now known as the Atlantic gap.
• Development of high performance interdiction forces, built around Mosquito and Beafighter squadrons mostly to interdict the movement of U-boats in the Biscay area. not that many U-boats were sunk in these attacks but many were damaged, or otherwise interdicted so as to reduce their times on station.

It would take another 15 months to make any real progress in this zone (ie the mid atlantic), and required LR and VLR aircraft to do the job. There was a ready supply of aircraft and crews available, but controlled by BC, who were obstinate, stupid, and voracious in their refusal to hand over anything like an adequate number of aircraft for long range maritime patrol. I am convinced that BC were prepared to lose the war if necessary to prove their point that Germany could be defeated by direct air attack alone. as I said, it was a stupid, obstinate and short sighted policy, that for a very long time was supported by Churchill. Only just in time for the return to the mid Atlantic gap in 1943 were sufficient resources of VLR aircraft diverted to support Atlantic Command.

stona said:

These bombs were not completely ineffective, but the failures did far outweigh the successes.

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I've read the 100-pounder was considered to be...

"probably ineffective, even with a direct hit, that the 250-pounder would have to explode within six feet of the pressure hull to do serious damage, and the 500-pounder at about eight feet".

Another problem was flying low to hit their elusive targets proved to be dangerous to themselves and the enemy. At least one Anson and two Fleet Air Arm Skuas were destroyed by their own bombs in September 1939 alone.

I would disagree your points 3 and 5. at least partially.

The Anson was far from an an adequate type and it was armed with a far from satisfactory weapon.

As Stona has told us the aircraft did spot 57 U-boats in 1939 alone (4 months) which isn't too bad considering the Germans probably didn't have more than 20 in operatianal areas at any one time. Radar would obviously improve things but the 20% damage record (8 damaged out of 40 attacks) doesn't look to good.
A plane with load of 1000lbs (four 250lb weapons?) might have been much more effective or even two 250lb weapons?
It might have converted a few more those "damaged" to kills and few more failed attacks to a least damaged. A damaged sub in German yards (not French) is out of action for at least a week if not more (3-4 days each way around Scotland minimum?)

The Anson used a crew of 3-4 men and needed almost as many mechanic, fitters, armament specialists, and so on as Blenheims or Hudsons.
For ten squadrons to be equipped with such a marginal plane borders on criminal.
And with an endurance of only about 4 hours (or less) it's ability to patrol at any distance was limited and even close patrols needed a fair number of aircraft per day.
A Blenheim looks like a super plane compared to the Anson.
Lets remember that a DC-2 finished 2nd and Boeing 247 finished 3rd in the 1934 London to Melbourne air race so a decent all metal aircraft was far from out of the ordinary in 1937-38.

Using a low powered trainer as a reconnaissance plane was false economy. Simply replacing 6-8 squadrons of Ansons with more capable planes requires little more man power but could, if given a better bomb than the 100lb, a much better chance of success. Replacing the biplane flying boats with something equal to even an early Catalina also expands CC ability without increasing man power.

the advantage is not only few more U-boats damaged/sunk but more merchantmen NOT sunk in 1939/early 1940. Which means the Germans are getting less results for the effort.

Had testing and development received higher priority in the mid to late 30s (1939 is a bit too late) then perhaps a decent 250-300lb weapon could have been designed.
However it also needed to be able to be dropped at monoplane speeds and monoplane atitudes. Unfortunately this was not the case and the speed and altitude requirements were slow and low meaning the dropping aircraft was still close. They also found the bigger bombs were going too deep to really hurt a surfaced or sub in process of diving.

A faster approach might also result in a few more attacks for the same number of sightings (or more successful attacks?) by giving the sub less time to dive and evade. Plane can cover a greater distance in the same amount of time.

Ansons cruised at 140-145mph at low altitude (max speed at sea level was 170mph) and the biplanes were even slower.

It took until 1941 for them to design a 250lb depth charge (as opposed to the 250lb anti sub bomb) which weighed 246lbs and had a charge weight of 170lbs (and this was soon considered too small) that would fit the standard 250lb bomb rack/carriers.

Had they started the war with such a weapon, even if filled with TNT and not Amatol, a t least a few attacks would have been more effective.

Later depth charges had flat or concave noses to reduce the tendency to ricochet (bounce), something else than might have been found with testing.
The MK XI depth charge first introduced in 1942 later achieved a drop envelope of 1250ft and 250kts.

It wasn't just radar that improved the kills, it was better weapons (later production of these depth charges used torpex fillers.) that helped turn contacts/sightings into successful attacks.

All CC had to do was find and report U-Boats in 1939-40. Sinking uboats was an added bonus, but not an absolutely necessary capability, whilst ever the battle was being fought in Coastal waters. that part of the battle can be broken into two sub-parts. firstly the battle around the inshore areas, including the north sea. initially the u-Boats (and indeed the KM surface units), were able to operate with a fair degree of impunity. but as the coastal forces were built up and organised, and began to work in concert with these early short range coastal aircraft, things began to change. The early aircraft types used, like the Walrus and the Anson, were the best things to use in this role. They were available,and they were cheap. they had a high serviceability rate because of their simplicity. introducing a new type, just as the battle for the inshore areas was getting underway was absolutely the wrong thing to do. Adopting more complex, less familiar types at this time unquestionably in my mind would have been a grave mistake.

The second phase of this early part of the battle, began about February 1940. most u-Boats were being pushed back out to sea, as a result of the large numbers of Coastal escorts, but importantly assisted by the Ansons (and similar aircraft) that were now able to complete one of the functions of CC ....coastal search, very efficiently. When the u-Boats moved further offshore, one of the things they did was expose the limitations of these early types. It was necessary to retain the Anson type forces, for the continued domination of the coastal waters, but also now add medium range twin engine bombers like the Blenheim, the Whitley and the PBY so that the waters now referred to as the western and north western approaches could be similarly covered. It took time to get this force organised, mostly because of the intransigence of BC. Losses began to climb again, But the real spike in losses occurred after the fall of France.. The RN was caught badly short of long range escorts that could operate to the MOMP (its standard fleet DDs did not have the range at that time for escort to the MOMP, though this did change with the development of Iceland), but just as badly, lacked the long range VLR aircraft to provide search capabilities. For the RN it became an undefended wilderness, both in terms of surface escorts, and also a/c. The SR coastal escorts and patrol aircraft....the ansons, were not responsible for this failure, but were still just as essential as they were in 1939 for the defence of coastal waters. what was missing from the force structure was the result of years of neglect, and near suicidal pre-occupations of a sister command, as they soaked up massive resources, and then refused to share them, or allocate them where they were most needed.

The question posed initially, was how to field a better CC. the automatic assumption is that the s/r coastal forces could be somehow passed over so that the later more deadly battle fought in the mid Atlantic could be fought more effectively. that is a wrong assertion, however. The battle of the coastal waters was actually more vital than the one fought later. It still needed aircraft, and the anson was more than adequate for that role. At the beginning training was so poor, and numbers so few that it took a while to get organised but organised it got.

The debacle in the mid Atlantic had nothing to do with that early fighting. It had everything to do with bad choices made by the RN and the RAF in the interwar ears, and during the early phases of the war.

Shortround6 said:

The Anson used a crew of 3-4 men and needed almost as many mechanic, fitters, armament specialists, and so on as Blenheims or Hudsons.
For ten squadrons to be equipped with such a marginal plane borders on criminal.
A Blenheim looks like a super plane compared to the Anson.

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This is something calculated as the Load/Personnel factor. Generally heavier aircraft carry a heavier load, but the requirement of large numbers of personnel to operate them lowers the factor, below that of smaller aircraft.
For example, from the Desert Air Force:

Mustang (at 2,000lbs per aircraft) on three squadron missions per day = 54,000 lbs.
Total personnel required = 243. L/P Factor 297

Marauder (at 4,000lbs per aircraft) on two squadron missions per day = 96,000 lbs
Total personnel required = 521. L/P factor 184

You can argue that the Desert Air Force got more 'bang for its buck' from the fighter bomber than from the medium bomber, when engaged in similar missions.

I don't have figures for the Anson, but they are not going to be great, particularly given it's large crew and light load (I imagine the numbers needed to maintain it and operate it on the ground would be similar to the Blenheim)!

fastmongrel said:

Nice info Stona. Do you know how the No30 fuse worked I always assumed the Anti Sub bombs were impact fused but obviously if they were expected to explode at 25 feet thats not the case. Was it a delay fuse activated by the deceleration when the bomb hit the water.

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I believe the No.30 was a pistol/detonator combination which allowed for a delay calculated to explode the bomb at about 25 feet below the surface. It wasn't a hydrostatic fuse and it wasn't instantaneous. A No.28 pistol was to be substituted when this bomb was used for 'land bombardment'.


The main filling on the Mk IV was either 45 lb of RDX/TNT at 60/40 or 44 lb TNT.

Graeme said:

Another problem was flying low to hit their elusive targets proved to be dangerous to themselves and the enemy. At least one Anson and two Fleet Air Arm Skuas were destroyed by their own bombs in September 1939 alone.

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The two Skuas were from 803 Squadron Fleet Air Arm, operating from Ark Royal. The boat they attacked was the U-30 of none other than Fritz-Julius Lemp which had just sunk the first ship of the war, the Athenia. Some reports say that they were shot down, but in fact their bombs skipped off the water, exploding under their aircraft, damaging both so that they were forced to ditch alongside their intended victim, which was undamaged. Kapitan Lemp took the airmen as prisoners and continued on his way. U-30 survived the war and was eventually scuttled at Flensburg in 1945. She had a long career, having been launched on 4th August and commissioned on 8th October 1936.

The Anson you mention is an even sorrier case. This time it was the RAF which came to grief, the Anson was from 233 Squadron based at Leuchars. On the second day of the war this Anson attacked an 'enemy' submarine off the Scottish coast, only to be damaged by splinters from its own bombs. It nearly made it home, but was forced to ditch in St Andrews Bay. The shaken but unharmed crew of the submarine Snapper were left wondering just who the enemy was at the beginning of the war

Cheers

Steve

parsifal said:

All CC had to do was find and report U-Boats in 1939-40. Sinking uboats was an added bonus, but not an absolutely necessary capability, whilst ever the battle was being fought in Coastal waters. that part of the battle can be broken into two sub-parts. firstly the battle around the inshore areas, including the north sea. initially the u-Boats (and indeed the KM surface units), were able to operate with a fair degree of impunity. but as the coastal forces were built up and organised, and began to work in concert with these early short range coastal aircraft, things began to change. The early aircraft types used, like the Walrus and the Anson, were the best things to use in this role. They were available,and they were cheap. they had a high serviceability rate because of their simplicity. introducing a new type, just as the battle for the inshore areas was getting underway was absolutely the wrong thing to do. Adopting more complex, less familiar types at this time unquestionably in my mind would have been a grave mistake.

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The Blenheim IV was being introduced to it's first squadron in Jan 1939, 14 squadrons were equipped with it by the end of the year.
5 squadrons of the RAF had received Blenheim Is by the end of 1937 (I don't know when they were declared operational), By Sept 1938 Blenheim Is had been delivered 16 home squadrons and one in Iraq. The Blenheim IV had been designed, in part, for overseas sales, and for the Canadian requirement for a coastal patrol aircraft.
Giving roughly 1/2 of those MK IV Blenheims to Coastal Command (and few dozen MK Is for training of ground crew) would have allowed for a much improved capability and very few technical difficulties.
I don't believe any Walruses were actually issued to Coastal Command, I am not saying that FAA squadrons didn't fly patrols with them, just that I have not seen (and could be wrong ) any sources that say a CC squadron was equipped with them. They were used (and very well) by air/sea rescue squadrons.
If pressed into anti-sub duty they were rated to carry SIX 100lb bombs or two 250lb bombs or two 250lb depth charges when they became available which obviously makes them a potentially more lethal opponent for the U-boat. They may very well have been used as anti sub aircraft in other areas than the British isles.

Had the British actually tested the 100lb anti sub bomb and it's cousins the 250lb and 500lb AS bombs in 1935/36 they may have found out how bad they were and given up the idea than a plane with two of them was even remotely effective. Wither this calls for an Anson with bigger engines to carry a pair of bigger bombs or a different aircraft is speculation but that is one "turning point" or "AH HA" moment.

The 100lb anti sub bomb was first designed to have 52lbs of HE with a steel tail, the MK II with an aluminum tail had 62lbs of HE but by the time you get to the production version in 1938-39 the MK IV had 44lbs of TNT, other fillings did change the weight slightly. Unfortunately so much was already invested in the 100lb bomb (existing bomb racks/layouts and techniques?) that production continued well into 1942 and in order to give it a slightly better chance of success it had a priority for the use of tNT/cyclonite (RDX) explosives that lasted until near the end of 1942. Which menas other ordnance had to make do with less powerful explosives.
The 250lb anti sub bomb carried 134lbs of explosive and the 250lb depth charge carried 170lbs and while thousands of those were dropped it was considered too small.

The question posed initially, was how to field a better CC. the automatic assumption is that the s/r coastal forces could be somehow passed over so that the later more deadly battle fought in the mid Atlantic could be fought more effectively. that is a wrong assertion, however. The battle of the coastal waters was actually more vital than the one fought later. It still needed aircraft, and the anson was more than adequate for that role. At the beginning training was so poor, and numbers so few that it took a while to get organised but organised it got.

The debacle in the mid Atlantic had nothing to do with that early fighting. It had everything to do with bad choices made by the RN and the RAF in the interwar ears, and during the early phases of the war.

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My interest is what could have been done to field a better CC in 1939-40. A better CC in that time period, should have, almost automatically, meant a better effort later on. And there are several possible knock on effects.

Every merchant ship saved in 1939-40 could make many more sailings in the years to come. According to U-Boat.net 728 ships were sunk or damaged in 1939-40 so saving just 10% would seem to be worthwhile.

If the Germans suffer higher losses (even U-boats tied up in port repairing damage) and sink fewer ships at what point do they decide that their resources are better spent elsewhere?

You also have about year from the start of the war until the French bases start to become effective?? Not just refueling but with torpedo storage and repair facilities (with parts) for the U-boats?

The British were not slow off the mark in developing depth charges to be dropped by aircraft.

I already mentioned what became the 450lb DC, complete with Mk VII hydrostatic pistol. It contained 290 lb of Amatol. It was too large to be carried by the Anson or Hudson and too few could be carried by the Sunderland or Catalina flying boats. Nonetheless, with a modified pistol (Mk X) the device remained in service throughout the war.

The impetus for something smaller came from the Fleet Air Arm, desperate to replace the anti-submarine bombs currently being carried by its aircraft. The new air dropped depth charge was an entirely naval project, undertaken by the Admiralty's Superintendent of Mine Design. This became the Depth Charge Type F, it weighed 246 lb and contained 170 lb of Amatol, and was available to both the FAA and RAF by November 1940.
It was redesignated Depth Charge Mk VIII, but was better known as the 250 lb DC. Officially known as the MK VIII DC (250 lb) it was cleared for general operational use on 23rd January 1941.

It was not perfect. At its lowest depth setting the pistol could detonate the device at a depth of 50 feet, double the optimal 25'. the 170 lb Torpex charge lacked sufficient punch even though it was 20% larger than that of the 250 lb AS bomb. These issues were solved by early 1942. Torpex was replaced by the 30% more powerful Amatol. The fuse was modified to work at a depth of 22 feet to 25 feet. Tail fittings were weakened to ensure a rapid breakaway on impact with the water and the nose was reshaped to concave to slow down the rate of sinking (not to prevent skipping off the surface). As a result of these improvements the depth charge was redesignated (again) as the Mk XI and the pistols to Mk XIV and Mk XVI. This was the version that remained almost unchanged from mid 1942, when it entered service, until the end of the war. It was on this version that production was concentrated.

Cheers

Steve

They were and they weren't. The converted surface ship depth charge was too large to be carried by just about any of the aircraft in CC service (and initially had some rather sever drop limits) Perhaps the biplane flying boats could carry one under each wing? Once the problem was identified (the anti-sub bombs weren't very good) they did move with good speed.

Had they found out the 100lb bomb was pretty much a dud and the 250lb marginal back in 1935/36 perhaps they could have started development of the 250lb depth charge sooner and had it in service in 1939 or early 1940. Even if development of the better explosives doesn't advance as fast as development of the bomb casing/fuse.
Having a weapon with about 4 times the explosive of the 100lb A/S bomb would have to have had some impact on damage/losses suffered by U-boats.

It's difficult to test these things on submarines. Obviously they did test drop them and sort some of the more obvious problems as best they could. It did take a long time, between 1924 and 1939!
In 1926 five 100 lb AS bombs had been dropped and four of them were rated as 'satisfactory' because they did not break up and did detonate below the surface. A sixth was detonated statically underwater and the fragmentation declared satisfactory. It was declared fit for service, in its MK I version, by 1928.
The Mk II, with a lighter nose and tail (and therefore better CWR) was tested in 1930 and deemed satisfactory, based on the 1926 criteria.
The Mk III followed with a strengthened suspension lug, allowing the aircraft carrying the bomb to be catapulted from an aircraft carrier without fear of leaving the bomb behind.
It was only in 1934, following trials with the larger 250lb and 500lb versions that the need for an extensive redesign became evident. It took two years before the Mk IV range with a solid nose and tail fusing was developed.
When the entire range proved less effective than had been imagined the Coastal Command Staff at RAF Northwood did begin to seek an alternative. This led to the adaptation of naval depth charge into the Depth Charge 450 lb Bomb Mk VII, with an added nose and tail to make a depth charge vaguely bomb shaped, later designated the 450 lb Depth Charge (DC).

I've covered the almost parallel development of the 250 lb depth charge by the Admiralty already. Experiments were undertaken in 1942 using HMS Graph which essentially showed what everybody already knew, that a charge detonated below the hull was more effective than one above it. German boats, particularly the most numerous Type VIIs, proved to be very strong and robust, withstanding considerable damage.

The British may have taken some time to develop a really effective air dropped anti submarine weapon, but far more important were the other technical developments, like ASV radar, that could actually put an aircraft in a position to attack a boat, 24 hours a day in combination with a Leigh Light

It's only fair to mention that a 600 lb AS bomb was developed, but not much used, 97 were dropped on submarines and a few on the Tirpitz! A 35lb AS bomb was also developed. This used a shaped charge and was only supposed to explode on contact with the boat, not the water. This was not the case, only 96 were ever dropped operationally before it was discontinued.

Cheers

Steve

The British scrapped and broke up something like 24 submarines (mostly L class) between 1930 and 1937 (and few more in 1938-39) so there should have been some sort of test target/s available if wanted.

Shortround6 said:

The British scrapped and broke up something like 24 submarines (mostly L class) between 1930 and 1937 (and few more in 1938-39) so there should have been some sort of test target/s available if wanted.

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It may be pertinent that when the Admiralty wanted to test its 250 lb depth charge HMS Graph was available to suffer the consequences, but that when the RAF wanted to test its AS bombs no submarine was available.

At the risk of sounding like a broken record, it is impossible to overestimate the malign effect of inter service rivalry on maritime aviation in the inter-war period. The Admiralty scrapped submarines, not the 'British'.

Cheers

Steve

The Graph was not used as a test target until 1944, three years after her capture and rather late in the game to affect things one way or the other.
However full scale models of her pressure hull had been built in 1942 and used for under water tests of shaped charge anti-sub bombs.

RAF, if they were serious, could have purchased either a hull or section/s of hull from the breakers (although the uproar in parliament might have been something to hear or built a mock-up/model.

We know the reasons Coastal Command was so poorly equipped in 1939 but none of them are really good ones or ones that couldn't have been changed with a little less head in the sand mentality.

They knew war with Germany was likely, they knew the Germans would probably use submarines in quantity (see 1935 treaty) and aside from Asdic, did very little to actually improve things from WW I and indeed, actually went backwards in some areas.
Even the 100lb AS bomb wasn't placed in production and issued until 1939 so the scores of Ansons available to fly in 1937 and 1938 having little to drop except 20 and 40 lb fragmentation bombs and smoke floats/flares.

Situation with torpedoes wasn't much better. You have told us how few there were available for CC but what was worse was that the ones available were only suitable for dropping by the Vildebeest or Swordfish. The Available torpedoes were supposed to be dropped at 100kts or under and from 100ft or under. The later wooden tails performed at least two functions. One was to act as an air brake to slow the torpedo from drop speed to water entry speed and the other was to try and insure a good entry angle to prevent/lessen damage to the torpedo. Of course the size of the tail made a joke of all the specifications calling for carrying torpedoes in inclosed bomb bays.
Unfortunately the restricted drop envelope was still in force during the early days of the Beauforts use. With both the Beaufort and Botha in pipeline (hundreds ordered) it seems strange that little or no work was done to see if the existing design of torpedo would work at higher speeds. Or did they expect the twin engine monoplanes to slow down to 100 kts for the final approach and release of the torpedoes?
Their own AA gunnery would stop enemy aircraft but enemy AA gunnery would not be able to stop planes flying at 100kts and 100ft?

There were plenty of 100 lb AS bombs available in 1939. A decision was taken to use only the Mk IV versions operationally and to keep the earlier suspect Marks as a war reserve against urgent contingency plans, pending a build up in numbers of the Mk IVs.
This was an operational decision, not a shortage per se.

During WW1 a bewildering variety of bombs were used against submarines, from 16 lb to 230 lb. By the time the RAF was formed in 1918 only two were specifically deployed for this purpose, the 230 lb and a new thin cased 520 lb RL.
The Admiralty agreed the need for two new anti submarine bombs of 250 lb and 500 lb in 1924, but contrary to Air Ministry requirements, amended its decision the following year, excluding the 250 lb version and substituting a 100 lb bomb.
The need to have two bomb sizes available provoked a conflict between the Admiralty and the Air Ministry/RAF as to what these should be.
One had to be big enough to be dropped alongside a submarine with the expectation of a single bomb making a kill. Both services agreed that the 500 lb bomb would do this. Both services also recognised that hitting a small and elusive target from anything but suicidal heights might require that a stick of bombs be dropped. The question was which was the smallest bomb worth using. The Admiralty went for the 100 lb and the RAF the 250 lb bomb. This had little to do with any evidence or research and more to do with conjecture and with what their aircraft could actually carry.
A typical British compromise was struck and three bombs, 100 lb, 250 lb and 500 lb were all developed.

Anti submarine bombs were by no means the only inadequate air dropped ordnance with which Britain entered WW2. Bomber Command started the war with the inadequate (I'm being polite) 250 lb and 500 lb GP bombs and the even more useless 40 lb GP and 20 lb F bombs.

Cheers

Steve

I am not sure the the 40lb and 20lb bombs were useless, mis-applied perhaps
As anti-personnel weapons for ground support they had some use or for bombing supply columns or vehicle parks.

For destroying buildings or ships they were not the best choice

The British seem to have had a real thing about using cheap steel/iron in bombs and artillery shells. Which often lead to small HE payloads which, instead of being economical, required more bombs, shells to dropped/fired to get the same effect. The knock on effect from that is more aircraft/guns are needed to delivery the greater quantity of bombs/shells so the supposed economy of using the cheaper materials really goes south in a hurry.

Getting back to the AS bombs some accounts claim the MK I and MK II were never put in production and so there was no reserve. One account (could very well be wrong) claims first production order placed in 1938 was for 50 bombs of each size. FIrst deliveries in 1939, how fast further orders were placed I have no idea and how fast further deliveries showed up after the initial ones is also unknown to me.
I don't know when the change was made from the MK I and II to the MK IV. A lot could have happened in the 9 months from January of 1939 to Sept. Perhaps those first 50 100lb bombs were MK I/IIs and the MK IV was introduced during 1939?

Point is, according to some accounts (which could be wrong) The Ansons, which were the quick and dirty substitute, were essentially unarmed during 1937-38(Munich crisis) which also points to how screwed up things were.