Wellingtons and sono-buoys (High Tea) (7 Viewers)

[ThomasP]

First operational tests of pre-production 'High Tea' by 210 Sqn supposedly took place in Jun/Jul'42, using Sunderlands out of Sullum Voe, Shetlands. 210 Sqn had (I think) officially transitioned from Sunderlands to Catalinas by this date, but possibly used a couple of available legacy Sunderlands for the tests? I have no idea if these 'High Tea' units were the US made CRT-1 series.

The UK first ordered 1000x CRT-1 sonobuoys and 30x R-2/AAR-3 receiver sets in Oct'42.


This is what I have for the CRT-1 series:

AN/CRT-1, Ø4.75" x 48"L as dropped, 14 lbs, 6 channels in 67.6-71.7 MHz 'Black' band, audio detection at 300 Hz to 8K Hz
in service 43

AN/CRT-1A, Ø4.75" x 44"L as dropped, 12.7 lbs, 6 channels in 67.6-71.7 MHz 'Black' band, audio detection at 100 Hz to 10K Hz
in service 1944

AN/CRT-1B, Ø4.75" x 45" as dropped, 13.5 lbs, 12 channels in 62.9-67.9 MHz 'White' band, audio detection at ?
in service 1944

Individual shipping tubes were either Ø5.25" for the CRT-1 & -1A or Ø5.5" for the CRT-1B (no idea why the difference).

NOTE the above dimensions and specs are from various manuals. However, I think there were a couple of different aerial sections that saw service - possibly of different length - which would result in different overall 'as dropped' lengths.


R-2/AAR-3 was usable with 67-72 MHz 'Black' band CRT-1 and -1A sonobuoys

R-2A/AAR-3 could receive both 'Black' & 'White' bands from 62-72 MHz.

As of Sep'49 the AN/CRT-1A/-1B series buoys with R-2A/ARR-3 receiver system was designated ARI.5286 in UK service.

 

[WATU]

First operational tests of pre-production 'High Tea' by 210 Sqn supposedly took place in Jun/Jul'42, using Sunderlands out of Sullum Voe, Shetlands. 210 Sqn had (I think) officially transitioned from Sunderlands to Catalinas by this date, but possibly used a couple of available legacy Sunderlands for the tests? I have no idea if these 'High Tea' units were the US made CRT-1 series.

The Sunderland trial really interests me. Blackett outlined his idea for a sonobuoy but the whole project was then passed to the US given the huge pressure British development resources were under. I have not spotted anything about a British device being designed during the war. So if 1942 trials happened they are highly likely to be a very early stage RCA AN/CRT design. Is it in the 210 ORBs or was it a 210 aircraft assigned to CCDU maybe? You don't hear of CCDU having dedicated flying boats (I think) so perhaps when needed they borrowed an operational one at a normal operational base. Was a formal CCDU report done in which case there is a good chance it is at TNA in AVIA7/1418. I have bits of that file but nothing relevant.

The rest of what you listed looked fine.

 

[WATU]

210 sqn ORBs for May-Aug 1942 offer no evidence. From web searches the squadron changed from Sunderlands to Catalinas from July 1940 to April 1941 ish. From the ORBs the main missions in summer 1942 were to Russia and other long range patrols unsuitable for Sunderlands. Does not seem any reason for the odd Sunderland to be held with issues of spares, ground crew, etc.

 

[GreatDaeld]

An informative paper on the sono-buoys, albeit from the US perspective: https://www.navairdevcen.org/PDF/THE EVOLUTION OF THE SONOBUOY.pdf

According to Chris Ashworth the use of High Tea in the Coastal Command was limited to "tentative operational use during the autumn of 1944", and by the beginning of 1945 ten squadrons had received the sono-buoys.

You don't hear of CCDU having dedicated flying boats (I think) so perhaps

"Flying units of the RAF: the ancestry, formation and disbandment of all flying units from 1912" by Alan Lake doesnt list any Sunderlands, however a Catalina IVB is mentioned.

 

[WATU]

120 Squadron was being equipped with sonobuoys in March 1944 but with inadequate supplies of hardware and buoys. Supply remained an issue for the UK and the US for a lot of 1944. The intention was to equip 162 aircraft that carried FIDO and 224 other ASW aircraft. By the end of 1944 the training plan was for 8 Liberator squadrons, 6 Sunderland and 2 Catalinas. That was expected to take six months. By the year end most Libs had been equipped and it was rolling out to others. In March 1945 there were frontline complaints of inadequate training time on courses with insufficient kit to get familiar with.
There was a big question over its effectiveness, at least in other than calm seas. One example had a propeller beat of 120pm being listened to but it was conclusively proved to be a whale. Mind you, the Navy was famed for depth charging many whales! The archives are littered with comments like "wishful thinking", "grossly exaggerated" and "dubious reports". Post-war with access to German records sonobuoy actions were lined up against U-boat locations. My summary follows.

• There were 32 examples between 3/11/44 and 4/5/45.
• Aircraft from CC, RCAF and USN were involved from a wide range of squadrons.
• Main aircraft type was, predictably, Liberator plus four Sunderlands and three Cansos.
• Positive sonobuoys sounds were claimed in 23 cases (72%) with contact lasting as long as three hours.
• Whenever a second aircraft arrived it always picked up positive noises.
• Sounds reported covered relatively slow beats of 55pm, below the taught minimum of 100pm, up
to 250pm accompanied by mechanical banging, hammering, clanking, hydroplane use, etc.
• In all positive 23 cases analysis of U-boat proximity concluded that no U-boats were involved. At
least one was close but did not schnorkel that day. In many cases there were no U-boats for 200+ miles.
• U-boat navigation was difficult while schnorkelling so there is a slight caveat that U-boat log
positions could be wrong which might affect one or two situations.
• The causes of the sightings were whales, whale spouts, porpoises, black fish, old markers and
commonly water spouts. The latter were also known as 'williwaws' or whirlwind squalls which could
include a terrific updraft sufficient to shake a large plane. These varied from a few hundred feet or
more to weak ones that just spread on the surface creating foam easily confused with feathering
and bow waves.