Development of MAT and HAT (Monoplane- and Hinged Air Tail) (3 Viewers)

[GreatDaeld]

Greetings!

I have been going through available information regarding the development of Monoplane Air Tail (MAT) in the RN/RAF.

From what i have gathered the MAT itself is based on the patent for a mechanical aid called "Bull Gear", invented by Captain J.A. Bull of the Royal Norwegian Navy. See attached patent. Controlled descent by means of pivoted rods controlled by air vanes on the sides of the torpedo. This was tested and used with the Vildebeest from 1935 and onwards. But the overall experience proved costly, and some further development was found to be needed.

The MAT themselves were first Mk I's through III, where the design changed some, but the overall function was the same. The descent of these MATs were controlled by a Drum Control Gear (DCG) stored in the torpedo-carrying aircraft. The torpedo was controlled by the DCG by two 18-foot wires attached to each horizontal rudder. This way the initial descent of the torpedo could be controlled so the nose would fall faster than the rear, thus gaining a favourable attitude for the optimal water-entry. The air tail would maintain the attitude after the wire would be expended, and detach itself from the torpedo upon entry into the water. The wires would also control any initial roll after release. The MATs gave some limitations to the carrying aircraft due to its span. Most aircraft did not carry their torpedoes externally but rather recessed or internally. Some aircraft were modified so the MATs could be fitted, while other solutions were made for aircraft like the Vickers Wellington.

The Hinged Air Tail (HAT) was designed as to fit inside the bomb bay of the Vickers Wellington. The HAT was controlled by the DCG, almost the same as the MAT Mk I-III. The difference was that the HAT only used one 18-foot wire per torpedo.

The downside of the use of the DCG for both the MAT Mk I-III and HAT was that the aircraft had to maintain its attitude until the 18-foots of wire had been expanded, thus leaving the aircraft and its crew extremely exposed. To overcome this, the MAT Mk IV was designed with its own gyroscope. The gyroscope would control the horizontal rudders in the air, and the mechanism was engaged upon release from the aircraft. This ensured that the torpedo aircraft could release their torpedoes and immediately begin maneuvering away.

A further development, the MAT Mk V, came as result of the increased performance of the carrying aircraft and the increased danger associated to launching torpedo attacks. The MAT Mk V was an MAT Mk IV upgraded with a drogue parachute to enable the aircraft to launch torpedoes at higher speeds and altitude than before.

MAT Mk VI i have seen mentioned as the title of a AVIA 16 ATDU report, but i have not found anything related to a post-war development of the MATs anywhere else. AVIA 16 in question: https://discovery.nationalarchives.gov.uk/details/r/C2378298.


TIMELINE

Bull Gear: 1935, the control mechanism was built into the aft section of the torpedo.


MAT Mk I: unknown year, 50-inch neutral air-foil, see photo below.

MAT Mk II: Unknown year, have not found any photos or information regarding specifics for this one.


MAT Mk III: Unknown year, wedge-section wings with adjustable flaps and endplates. Likely the most numerous type of the MATs. See photo below.

HAT: Unknown year, i have been unable to find much more information regarding the HAT.


MAT Mk IV: ~1943, horizontal stabilizers controlled by a gyroscope.


MAT Mk V: ~1945, MAT Mk IV fitted with a drogue parachute

MAT Mk VI: 1947, post-war development with unknown result.



The photos and most of the information i collected from RAF Historical Society Journal 45, attached.



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I would greatly appreciate any inputs towards this matter, as i am very interested to learn more!

 

[EwenS]

As as you will be aware, page 128 of the RAF Historical Society Journal has a photo of the Bull Gear as fitted to the Mk.XIV torpedo and notes

"This expensive and complicated fitting was mainly
associated with the fast but equally complicated and therefore disliked
Mk XIV torpedo of 1935 and was associated almost exclusively with
the RAF's Vildebeest biplane. The Mk XIV torpedo was some 220 lbs
heavier and 30% faster than the Mk VIII it replaced, and carried
slightly more explosive."

The last Vildebeest squadrons in the RAF were in Malaya and flew operationally against the Japanese in Dec 1941 / Jan 1942 (36 & 100 squadrons). Navweaps has a note for the Mk.XIV torpedo:-

"Almost the entire stock of this model was lost with the surrender of Singapore. Considered to be less robust than the Mark XII. Use methylated spirits as fuel."

World War II Torpedoes of the United Kingdom/Britain - NavWeaps

www.navweaps.com

I'm not aware of the RN ever having used the Mk.XIV. They moved from the WW1 era 18" Mk.VIII torpedo to the Mk.XI designed in 1934, which entered service in 1936, to the improved Mk.XII designed in 1935 as an improved Mk.XI, which entered service in 1937. This became the main air launched torpedo for both the RN & the RAF in the first half of WW2. It was superseded by the Mk.XV designed in 1942 which entered service in 1943 with both services.

Regarding carriage of torpedoes, RN aircraft like the Swordfish, Albacore and Barracuda and the RAF Vildebeest all carried their torpedo externally. The bomb bays of both the Wellington and the Hampden had to be modified to allow torpedo carriage.

There is an RAF training film about the operation of the Mk.XII torpedo dated 1942 that I have posted before that shows:-
1. The operation of the MAT from about 16.40 and,
2. The MAT being fitted to a Mk.XII torpedo after the torpedo had been loaded onto a Beaufort from 32.00 onwards.

The purpose of The Drum Control Gear was simply to stabilise the torpedo for the very short period of time that it was subject to the disturbed airflow around the dropping aircraft. Given the effects of gravity on an object like a torpedo falling clear of an aircraft, it would only have been a matter of just over a second before the reels unwound their 18ft of wire. After that the air vane attached to the side of the torpedo in conjunction with the servo motor (part of the depth keeping mechanism after the torpedo enters the water) and connected to the MAT kept the torpedo in the correct attitude.and The film probably explains it better.

View: https://www.youtube.com/watch?v=L9ooDSXtlHc

While the RN fitted MAT to torpedo carrying Barracudas, I've never seen a MAT equipped torpedo on a Swordfish or Albacore. Barracudas only undertook one operational torpedo dropping sortie, despite the years of training the crews put in.

The necessity for the later MAT gear versions for faster aircraft largely disappeared with the end of WW2. For the RAF plans to re-equip Coastal Command strike squadrons with the Bristol Brigand TF.1 died in early 1946. Post-war the torpedo dropping function in the RN moved to the Firebrand, but existing equipment proved adequate for it. While the Westland Wyvern was designed as a successor, by the time it became operational it was designated as a Strike aircraft using bombs and rockets.

 

[GreatDaeld]

As as you will be aware, page 128 of the RAF Historical Society Journal has a photo of the Bull Gear as fitted to the Mk.XIV torpedo and notes

"This expensive and complicated fitting was mainly
associated with the fast but equally complicated and therefore disliked
Mk XIV torpedo of 1935 and was associated almost exclusively with
the RAF's Vildebeest biplane. The Mk XIV torpedo was some 220 lbs
heavier and 30% faster than the Mk VIII it replaced, and carried
slightly more explosive."

The last Vildebeest squadrons in the RAF were in Malaya and flew operationally against the Japanese in Dec 1941 / Jan 1942 (36 & 100 squadrons). Navweaps has a note for the Mk.XIV torpedo:-

"Almost the entire stock of this model was lost with the surrender of Singapore. Considered to be less robust than the Mark XII. Use methylated spirits as fuel."

World War II Torpedoes of the United Kingdom/Britain - NavWeaps

www.navweaps.com

I'm not aware of the RN ever having used the Mk.XIV. They moved from the WW1 era 18" Mk.VIII torpedo to the Mk.XI designed in 1934, which entered service in 1936, to the improved Mk.XII designed in 1935 as an improved Mk.XI, which entered service in 1937. This became the main air launched torpedo for both the RN & the RAF in the first half of WW2. It was superseded by the Mk.XV designed in 1942 which entered service in 1943 with both services.

Regarding carriage of torpedoes, RN aircraft like the Swordfish, Albacore and Barracuda and the RAF Vildebeest all carried their torpedo externally. The bomb bays of both the Wellington and the Hampden had to be modified to allow torpedo carriage.

There is an RAF training film about the operation of the Mk.XII torpedo dated 1942 that I have posted before that shows:-
1. The operation of the MAT from about 16.40 and,
2. The MAT being fitted to a Mk.XII torpedo after the torpedo had been loaded onto a Beaufort from 32.00 onwards.

The purpose of The Drum Control Gear was simply to stabilise the torpedo for the very short period of time that it was subject to the disturbed airflow around the dropping aircraft. Given the effects of gravity on an object like a torpedo falling clear of an aircraft, it would only have been a matter of just over a second before the reels unwound their 18ft of wire. After that the air vane attached to the side of the torpedo in conjunction with the servo motor (part of the depth keeping mechanism after the torpedo enters the water) and connected to the MAT kept the torpedo in the correct attitude.and The film probably explains it better.

View: https://www.youtube.com/watch?v=L9ooDSXtlHc

While the RN fitted MAT to torpedo carrying Barracudas, I've never seen a MAT equipped torpedo on a Swordfish or Albacore. Barracudas only undertook one operational torpedo dropping sortie, despite the years of training the crews put in.

The necessity for the later MAT gear versions for faster aircraft largely disappeared with the end of WW2. For the RAF plans to re-equip Coastal Command strike squadrons with the Bristol Brigand TF.1 died in early 1946. Post-war the torpedo dropping function in the RN moved to the Firebrand, but existing equipment proved adequate for it. While the Westland Wyvern was designed as a successor, by the time it became operational it was designated as a Strike aircraft using bombs and rockets.

Thank you for the informative reply!

I have seen that training film, it is really thorough and a good addition to the thread! It looks to me as the MAT portrayed is the Mk III, with its endplates. Interestingly, the air vane can also be seen on the Bull Gear, marked as number 15 on the patent sheet. Its called the "auxiliary rudder".

Regarding the Bull Gear and Vildebeests, I am of the opinion that it is rather dubious whether the Bull Gear was kept operable until the surrender of Singapore. As it was stated to be an expensive mechanism and other, more affordable designs appeared. But then again, I am not certain the MATs could be used for the Mk XIV torpedo.

The figure showcasing the MAT Mk I above was borrowed from the RAF Society Historical Journal 45, page 130, with the description: A Mk I Monoplane Air Tail (MAT) fitted to a Mk XII torpedo on a Swordfish with its Drum Control Gear (DCG) discernible within the fuselage. I have also found a photograph with what looks like a MAT Mk III: Swordfish. I believe the development of the MATs and similar were considered a secret during the war, hence very few photographs were taken of these devices.

Also found some photos of Albacores with what could be MATs with endplates: Albacore 1, Albacore 2. Some weird colours/shadows, but could be explained by a differing colour between the MAT and the torpedo itself.

Yes, the Journal 45 described the relationship between the torpedoes and the torpedo-aircraft well: the performance of the aircraft always being one step ahead of the torpedoes it was supposed to carry. This chase came to an end some time after the end of the second world war for different reasons.

 

[EwenS]

Thanks for the photos.

The one of the Swordfish triggered a memory of where I had seen it before. It is of either Swordfish II serial DK747 or HS671 (probably the latter) during RATOG trials at RAE Farnborough during Dec 1943. Info taken from "Farnborough and the Fleet Air Arm" by Geoffrey Cooper who was employed at the RAE in WW2 and beyond. You can see the stubs of the RATOG rockets under the trailling edge of the wing with the rocket blast extending aft of the aircraft which is just at the point of becoming airborne. The variety of aircraft in the background, including an Avenger, and the distinctive buildings reinforce the location.

So a trials aircraft not an operational one. Aircraft used for that purpose could be fitted to carry all sorts of non-standard equipment.

By December 1943 the Swordfish had been superseded in the torpedo bomber role by the Barracuda TBR.II. By then they were being used from escort carriers and MAC ships in the ASW role using rockets or depth charges, or attached to Coastal Command operating over the southern North Sea and English Channel in the anti-shipping role (particularly anti E-boat) using rockets or 250lb bombs.

I'll look into the Albacore photos more deeply tomorrow.

 

[GreatDaeld]

Yes, it does look like it is fitted with the ring on the nose, instead of a pistol. I imagine the wide MAT could be a cause for concern, so it may very well be testing of the RATO gear in unison with the MAT. Interesting read, the chapter regarding the RATOG!

Swordfish, here is another photo. The torpedo is fitted with a pistol, and what resembles a MAT Mk I can be viewed in the back. Again, not a perfect photo!

 

[GreatDaeld]

On https://www.secretprojects.co.uk/threads/avro-manchester-variants-origins-and-projects.19509/, regarding the development of the Avro Manchester, the attached photo was shared.

It apparently is from when the project was still made to be torpedo capable. In the head-on view it looks like the torpedoes were supposed to have some sort of air tail, but it doesnt look anything like any of the MATs. Could it have been a version of the HAT, later supposedly used on the Vickers Wellingtons? The sketch is probably dated to sometime mid-1930s, so it could just be to conceptualize that the torpedoes could be fitted with an air tail.

 

[GreatDaeld]

Also, regarding the Vickers Wellington:

from https://saafww2pilots2.yolasite.com/don-tilley-photographs.php, appears to show some sort of air tail on what looks like a torpedo. It does look a bit weird, as the shadow is lined up with the top of the torpedo, instead of centered like the known photos of MATs. It could perhaps be HAT or some other device.

https://www.britishpathe.com/asset/65454/

In this video the loading and dropping of torpedoes are shown, and especially the last segment (1:23) is interesting. Still taken just as the torpedo is about to cross the horizon:

The torpedo is fitted with an air tail. In the beginning of the video the torpedo can be seen loaded onto the aircraft, albeit without an air tail. The bomb bay doors close, what is notable is that the bay doors are split. Later, the aircraft are shot in profile, then it can be seen that there is a cut-off part in the rear of the bomb bay. This could possibly be to fit the air tails. The air tail in this video does look like it is centered on the torpedo, as opposed to the torpedo in the photograph above.

There is also this photo: Wellington, which also has the cut-away section of the bomb bay. It looks to be loaded with something, but it is difficult to see details.

 

[EwenS]

On https://www.secretprojects.co.uk/threads/avro-manchester-variants-origins-and-projects.19509/, regarding the development of the Avro Manchester, the attached photo was shared.
View attachment 896037

It apparently is from when the project was still made to be torpedo capable. In the head-on view it looks like the torpedoes were supposed to have some sort of air tail, but it doesnt look anything like any of the MATs. Could it have been a version of the HAT, later supposedly used on the Vickers Wellingtons? The sketch is probably dated to sometime mid-1930s, so it could just be to conceptualize that the torpedoes could be fitted with an air tail.

As I posted on both the Secret Projects site and this one a couple of years ago, the torpedo dropping requirement was the first element in Spec P.13/36 to be dropped (-pardon the pun!). That Spec, issued in Sept 1936, led to both the Manchester (and then the Lancaster) and the Halifax. That happened on 26th Aug 1937. See post #6.

Was a four engine torpedo bomber ever considered?

The torpedo dropping requirement in Spec P.13/36 that led to the Manchester was dropped on 26 Aug 1937, long before it ever flew or the Lancaster was conceived. Other elements dropped before the Lancaster was conceived were:- The catapult launch requirement was dropped on 4 July 1938. However...

ww2aircraft.net

Because it happened so early in the design process, and Handley Page were able to switch to a four engined configuration, the design that became the Halifax was able to dispense with the long bomb bay it would otherwise have had to have.

There is a further issue with this configuration. As designed the Manchester had a bomb bay length of 33ft, as did the Lancaster. The torpedoes entering service around then (Mk.XI, XII & XIV) were all around 16ft long.

So while two TT could fit longitudinally in a Manchester bomb bay, that would not be possible if fitted with an air tail once you allow some free space forward, between and aft the weapons.

 

[GreatDaeld]

Yes, i noticed your username in the thread and figured it was more than a coincidence!

Did the british not use any 4 engined torpedo bombers until the Shackleton? Perhaps a Liberator variant late war?

Also, while the Manchester could not fit two torpedoes with air tails one after the other, do you reckon the Wellington could fit two beside each other? Assuming the air tails are roughly 50 inches wide.

 

[GreatDaeld]

Found some interesting photos from the photo albums of 458 RAAF Squadron: Official Squadron Albums | 458 RAAF Squadron.

From Chapter 1 1941-1942: "1500lb torpedo" with some add-on on the tail. Could be an air tail of sorts.

Spoiler

From Chapter 3 1943-1944:
"Lethal load": Torpedo with MAT, inscription looks to be "XV 476" on the air tail. Could signify torpedo Mk XV, or which aircraft it is due to be mounted to?

"Torpedo in position": Externally mounted torpedo with MAT. Is anyone able to ID the aircraft? My first thought was Martin Marauder, as No. 14 Squadron was in Algeria roughly at the same time as the 458 RAAF. However, they were positioned at different airfields. Also the header of the page is Protville, Tunisia. Probably a difficult angle for identification...

Spoiler

 

[cammerjeff]

Does this picture of a RAF B-26 show an air Tail?

source https://saafww2pilots2.yolasite.com/don-tilley-photographs.php

 

[EwenS]

Yes, i noticed your username in the thread and figured it was more than a coincidence!

Did the british not use any 4 engined torpedo bombers until the Shackleton? Perhaps a Liberator variant late war?

Also, while the Manchester could not fit two torpedoes with air tails one after the other, do you reckon the Wellington could fit two beside each other? Assuming the air tails are roughly 50 inches wide.

You seem to be confusing the use of anti-shipping torpedoes on the one hand and the use of homing torpedoes for ASW on the other. Two entirely different types of weapon used for completely different purposes.

The RAF dropped the torpedo as an anti-shipping weapon around 1946/47. The RN continued to use it for a few more years. The last time the USN dropped an anti-shipping Mk.13 torpedo in anger was May 1951 in Korea.

The B-24 Liberator had two separate bombs bays each with its own set of roller shutter doors with structural components keeping them separate. The bomb racks were on the centre line in each bomb bay with individual bomb stations stacked vertically up each rack. The largest weapons able to be carried internally were the 2,000lb bomb and the Mk.24 Mine or Homing Torpedo (codename Fido). These weapons were 90in and 84in (7-7.5ft) in length respectively. So no anti-shipping torpedo could be carried internally, just that ASW homing torpedo.

While some later models had external racks between the fuselage and inboard engines rated for 4,000lb bombs I've only ever seen them carrying drop tanks. I haven't measured it, but I suspect that a torpedo, even a 13-14ft USN Mk.13 might have come into contact with the props. It certainly didn't figure in the loads cleared for use on USN PB4Y-1 Liberators.

As for the Wellington, it was capable of, and did in fact carry two torpedoes side by side in the bomb bay. The description I have of the Med conversion is as follows.

"The usual bomb carriers were replaced by a pair of booms to carry two torpedoes. To ensure the torpedo hit the water in the right attitude, wood and canvas aerofoils were attached to the rudder and elevators of the torpedo, which broke away on entry into the water. To accommodate these aerofoils, there was a 'V' cut out at the rear of the bomb doors, which allowed the to be carried in the bomb bay, keeping drag to a minimum."
Taken from "Vickers Wellington" by Philip Birtles.

Note he does not describe the attachment as a MAT / HAT.

There is a photo in this article showing two torpedoes being loaded on a Wellington of 38 squadron.

https://www.key.aero/article/38-squadrons-wellington-torpedo-bombers

There is a photo of one of these Wellingtons with the cut away bomb bay on another thread on this site.

Wellington torpedo-bomber - crude sight?

Hi There are many examples of simple bomb and torpedo sights often designed by squadron aircrew. They mostly are variations of a rifle with a foresight and backsight to assist the pilot and sometimes the 2nd pilot to allow approaches from both sides. I am attaching two pictures of Wellington...

ww2aircraft.net

Wellington torpedo-bomber - crude sight?

Hi There are many examples of simple bomb and torpedo sights often designed by squadron aircrew. They mostly are variations of a rifle with a foresight and backsight to assist the pilot and sometimes the 2nd pilot to allow approaches from both sides. I am attaching two pictures of Wellington...

ww2aircraft.net

When it comes to the Shackleton it was not designed to carry anti-shipping torpedoes. It was designed to carry ASW homing torpedoes.

 

[EwenS]

Does this picture of a RAF B-26 show an air Tail?
View attachment 896065
source https://saafww2pilots2.yolasite.com/don-tilley-photographs.php

The only RAF or Commonwealth squadron to fly the B-26 Marauder as a torpedo bomber was 14 squadron. It converted to the Marauder Mk.I starting in Aug 1942 while based in Egypt and began to fly operations on the type at the end of Oct 1942. It flew a mix of general recce, bombing, mining and a few torpedo sorties. The last torpedo sorties were flown on 21st Feb 1943.

It converted to the type at LG224 in the Canal Zone and moved forward to Berka III in Libya in Feb 1943. Further moves took it to Algeria and finally to Protville in June 1943.

The History of 14 Squadron

Torpedoes were carried externally on Marauders, on a special rack fitted under the bomb bay as illustrated in the middle photo off the last Protville page.

The number of targets in the Med worthy of a torpedo shrank rapidly during 1943 with the result that it's use ceased by the end of the year. It seems highly unlikely that the Marauder photos with torpedoes were taken at Protville.

As with a number of units sent to the ME in 1942, the history of 458 squadron in the Med became complicated by the separation of its ground crews from its aircraft. Ground crews left Britain in late March 1942 by sea and around the Cape in convoy WS17, and arrived at Kasfareet, Egypt on 26th May and moved to Fayid on 30th. They were then used to maintain aircraft from other squadrons. That probably explains the photos of the Liberator B.II with the black undersides (most likely those of 159 squadron).

Meanwhile the crews had flown their Wellingtons to Egypt where they were absorbed into other Wellington squadrons then in theatre.

The squadron re-emerged as a complete unit in Sept 1942 to begin operations with Wellington Mk.Ic / VIII on 1 Nov 1942 It then flew AS patrols, anti-shipping sweeps and minelaying sorties as well as a few torpedo sorties.flown It was early June 1943 before it reached Protville.


The ORBs for these squadrons can be downloaded FOC from the National Archives if you want to delve deeper.