Coastal Command and the likes of Monica and Boozer

[WATU]

Over the Atlantic airborne radar detectors like Monica and Boozer would have had no value so were presumably not fitted to avoid non-essential weight. My question is whether Coastal Command aircraft operating at night over the Bay of Biscay would have used them. This could be on Leigh Light aircraft or others such as Sunderlands that relied on flares. Did German nightfighters operate over the Bay or were they all deployed to protect the land targets from the Bomber Command attacks? I assume the later but don't have any evidence. Anyone able to confirm either way and if so what sources are there please?
Paul

 

[EwenS]

AFAICT there were some limited Luftwaffe night operations over the Bay of Biscay in late 1943 and into early 1944 under the auspices of Kommando Kunkel. They seem to have had little or no success. I've not read anything of CC aircraft being fitted with either Boozer or Monica. But with little threat there would be no need.

Kommando Kunkel (page 1)

www.ghostbombers.com

 

[frankv]

Later in the war, U-boats had radar. A comment I read was that U-boat commanders didn't like to use their radar, because they thought it gave away their position. So perhaps Boozer was used to detect U-boats?

U-boat Radars - Technical pages - German U-boats of WWII - Kriegsmarine - uboat.net U-boat Radars - Technical pages - German U-boats of WWII - Kriegsmarine - uboat.net

 

[MIflyer]

I read that tests were done on the use of Monica to enable single seat nightfighters such as the Typhoon to determine when they were within gun range of V-1's. It was very hard to look at the V-1 engine flame and know that you were close enough to hit it but not so close that if the flying bomb exploded it might be fatal to you. So with a Monica/APS-13 installed to look forward and serve as rangefinder, when the warning light came on the pilot knew he was close enough to hit the V-1.

Also the Metaxa radar warning receiver was built by a French company and the U-boat captains suspected it had been sabotaged by the French to emit signals that Allied ASW aircraft could home in on. Of course in reality the receiver probably was not even looking at the right frequency, so the U-boats equipped with it were getting hit simply because they were vulnerable to detection. Using Monica while on ASW missions might have actually caused the Metaxa to go off.

 

[EwenS]

Monica, Boozer, Fishpond (a rear warniing radar attachment for H2S) and AGLT were all designed at the request of Bomber Command specifically to defend its own aircraft while over enemy territory. They were not intended, at least to begin with, for more general use. And BC never reached a point with any of these sets whereby its entire fleet was fitted with them.

Monica - the story began in late 1940 but it was mid-1942 before any trials could begin. General introduction to Bomber Command aircraft was delayed by worries that it would quickly be jammed and thereby made obsolete. Then it was decided that it couldn't be introduced piecemeal, it had to be introduced in quantity across the BC fleet starting with the Halifax squadrons. Both retrofitting to existing in-service aircraft as well as production line fitting of the necessary wiring began in Spring 1943 with the first operational use in June 1943.

Monica Mk.I only gave an audible warning to the crew of an aircraft when the radar detected. The range was initially set at 1,000 yards which was rapidly found to be too great for aircraft operating in a bomber stream. There was no directional indication nor any IFF facility. Its use also interfered with some other systems like Oboe. And it couldn't be used below 3,000ft due to ground returns (so any use in Coastal Command would have been severely limited). So it generated a lot of false alarms. In July 1943 sets were modified to allow selection of ranges of 1,000, 800, 600 & 400 yards as automatic settings to be selected at the choice of the squadron commanders.

By late 1943 it had been decided to give Monica a visual display. 650 ASV.II sets were taken from Coastal Command to produce Monica IIIA sets in early 1944. That was followed by a productionised Monica IIIB. But at that stage not all the BC aircraft intended to get Monica had received a set.

As 1944 went on the loss rates amonst Monica equippped aircraft gradually increased. In July a Ju 88G-6 landed at Woodbridge by mistake and delivered to the RAF an entire suite of the lastest Luftwaffe radars and homing devices. That included a FuG 227 Flensburg set designed to home on the Monica radar emissions. The result was that BC, with the exception of 100 Group, stopped using Monica in Sept 1944.

Boozer entered service at the end of 1942 initially as a passive system to detect Luftwaffe ground control and gun laying radars. It was enough to help a BC aircraft to avoid areas of flak & searchlights in particular. On receipt of a signal it lit a red light in the aircraft. In developed double channel form it could differentiate GCI from GL radars, indicated by different intensities of red light, and in triple channel form it could also detect early Luftwaffe AI radars, lighting a yellow light in the aircraft. It was late 1943 before the latter set was available. The lights were in both the pilot's cockpit and the wireless operator's station. By Aug 1943 about 400 BC aircraft had received any form of Boozer set.

CC made some limited use of Boozer in 1943/44 tuned to U-boat radar frequencies but BC had priority for the equipment.

Boozer was removed from all BC aircraft except Mosquitoes in Sept 1944 because it was no longer effective against the S.N.2 radar then being fitted to Luftwaffe night fighters (another gift from the Woodbridge Ju 88) and it was no longer effective against GCI/GL radars.

A full description of the development of these systems can be found in the RAF Signals Narrative Vol III starting at page 357 for anyone who wants more detail.

Thematic Studies

Thematic Studies Airborne Forces Airborne Forces 32.3 MB Arnhem: The Air Reconnaissance Story - Third Edition 2024 14 MB - Airfield Air Defence Since 1933 8.4 MB - Air Sea Rescue 22

www.raf.mod.uk

RAF Signal Narrative vol VI from p 163 covers CC use of radar detection systems including the limited use of Bagful, Boozer & Greenbottle.

But once U-boats began to use schnorkels from mid-1944 and spent the great majority of their time underwater, the need for radar detectors by CC more or less disappeared.

 

[WATU]

Coastal Command issued a monthly progress report during the last two years of the war. The following reports mention Boozer which was fitted in the two Halifax squadrons based on the south coast with one trialled but not taken up in Liberators.

Report 3 August 1943

Halifax II GR LR 58, 502 sqns. Boozer both sqns fitting commenced. Both at Holmsley.

Liberator V GR 224 & 311 sqns. Boozer Trial installation complete. One fitted in 311 sqn aircraft, awaiting air test at Beaulieu.

Report 4 8 September 1943

Halifax II GR LR 58, 502 sqns. Boozer both sqns fitting ongoing.

Liberator V GR LR 53, 224 & 311 (Czech) sqns. Boozer fitted in 1 of 311.

Report 5 28 September 1943

Halifax II GR LR 58, 502 sqns. Boozer both sqns fitted.

Liberator V GR LR 53, 224 & 311 sqns. Boozer 1 of 311 for trials.

Report 6 26 October 1943

Halifax II GR LR 58, 502 sqns. Boozer fitted in 8 of 58 and 10 of 502. 23 sets held.

Liberator GR LR 53, 224, 311 sqns. Boozer 1 of 311 fitted.

Report 7 30 November 1943 – No mention of Boozer.

 

[EwenS]

Worthwhile quoting from the RAF Narrative Vol VI.


"In June 1943 evidence, obtained on this occasion from photographic. inter-
pretation sources, again indicated that U-boat anti-surface vessel radar worked
on or near a wavelength of 80 centimetres. Although development of Bagful
and Blonde had been accelerated, without adverse affect on other development
work, delivery of Bagful to Coastal Command was not expected to begin until
the end of August 1943, and manufacture of Blonde would not be started until
the end of July. As an immediate measure twelve aircraft of Nos. 58 and
502 Squadrons were therefore equipped during July with Boozer suitably
modified for the purpose of testing the correctness of the assumption that 80
centimetres was approximately the wavelength used by the enemy. Boozer
was a manually-operated receiver which could be modified to cover any selected
wavelength within a narrow waveband chosen for investigation. It gave
visual indications of the reception of a signal and entailed the addition of a
special operator to an aircraft crew. Initially it had been designed for use in
Coastal Command . but was developed for use in Bomber Command as a tail-
warning device when an urgent operational requirement had arisen, As the
probable enemy waveband was already closely, and comparatively finely.
defined, the T.RE. began development of a suitable homing system. Arrange-
ments were made for a Liberator and a Wellington XII to be prototyped on the
highest priority for modified Serrate, later given the codename Greenbottle,
and a transmit.ter to operate on the enemy wavelength, for use in conjunction
with the Serrate prototype so that tactics might be determined, was made an
urgent requirement.« If the prototypes were successful, Greenbottle was to
be installed in all Liberators and Leigh Light Wellingtons of Coastal Command. 5
Modified Serrate, or GreenbotUe,. consisted of an A.S.V. M.i.rk II receiver
slightly modified to give azimuthal indications ooly between wavelengths of
75 aod 100 centimetres, and a Fleet Air Arm type of indicator unit.
Delay in the supply of aerials protracted the Boozer installation programme,
and by the middle of August 1943 only two aircraft were in operational use;
the precise wavelengths used by the enemy had not been firmly established.
Installation in both squadrons was, l10wever, completed by the middle of
September. At that time the Wellington Greenbottle prototype was awaiting
trials at the C.C.D.U., 50 sets of Greenbottle and associated aerial arrays were
ready for installation, and 19 Bagful receivers had been allocated to Coastal
Command. 6 Installation of Greenbottle in the aircraft of No. 407 Squadron
was completed in October 1943 and that of Bagful in Nos. 172 and612 Squadron
in November 1943.
Until employment by the Germans of Sclmorchel made U-hoat radar investi-
gations unnecessary, a considerable number of sorties were made by Coastal
Command aircraft equipped with Bagful, Boozer and Greenbottle, but because
only limited use of radar was made by U-boat commanders, no contacts that
could be identified positively as U-boats were obtained. [1 see footnote below] During the spring
of 1944 many signals were recorded, but they could not be so related in any
way with visual or A.S.V. sightings; the majority probably emanated from
coastal radar stations and E-boats."

There is also a footnote

"1 A number of U-boats, especially when surfaced because of Schnorchel or battery trouble,
used radar bearing for blind firing of their A/A guns at extreme range against aircraft in an attempt to force them away. A Halifax was shot down over the Bay of Biscay on 12 March
1944 by U-boat U.311. The commander reported that warning of the approach of the
aircraft was given by his radar set, and firing was controlled by radar (Admiralty Trans-
lation P .G.30342). Good results with Hohentwiel were also reported in August and Sep-
tember 1944."

Notes
1. Blonde development was cancelled at the end of 1943.
2. The Boozer sets installed in CC aircraft were modified to detect U-boat radar frequencies, not GCI/GL or AI frequencies i.e for research or an offensive rather than the defensive purpose as used in BC.
3. Boozer was chosen for fitment in the 2 CC Halifax squadrons employed in ASW work. Same type as was being given priority for such defensive systems in BC. (Other CC squadrons used the Halifax for meteorological recce e.g. 518)
4. Installation of Boozer in CC aircraft entailed the carrying of an additional crew member, unlike in BC. Again suggesting the research role allowing the receiver frequency to be tuned in flight.
5. The lack of identifiable success highlighted in the final para.
6. The story about who initiated Boozer development differs slightly between the two volumes of the Narrative

 

[EwenS]

On 12 November 1943 HQ CC issued very detailed instructions about the equipment fit of Liberators already in the Command and those about to arrive (the Mk.VI). There was a "Signals" section which reads as follows:-

Long Range Liberator Aircraft (Mk.V & VI) (para 15) & Very Long Range Liberator Aircraft (Mk.I, III, V & VI) (para 14)

"Signals
(i) Radio Altimeter to be fitted when available to all aircraft
(ii) "Bagful" to be fitted to selected aircraft
(iii) "Walter" to be fitted when available to all aircraft
(iv) Radio Sono Buoy to be fitted when available to all aircraft
(v) "Greenbottle" to be fitted to selected aircraft.
(vi) Gee A.R.I. 5083 to be fitted when available to all aircraft
(vii) The auxiliary power unit to remain installed."

There is no mention of Monica nor of Boozer anywhere in that document.

I took this from the very detailed 311 squadron book. The authors provide some notes about various devices mentioned.

Bagful - was self-recording L band equipment for the interception of signals from Wurzburg radar, recording the wavelength, time and duration of the received signal.

Walter - was a small portable radar responder beacon which could be used by survivors of a ditching or forced landing to provide search aircraft with an identifiable radar echo. It had a maximum pick up range of about 25 miles.

Greenbottle - was the Colour (or Rainbow) Codename for device for homing on U-boat signals.



In the RAF Narrative "Greenbottle" was described as

"Modified Serrate, or Greenbottle,. consisted of an A.S.V. Mark II receiver
slightly modified to give azimuthal indications only between wavelengths of
75 and 100 centimetres, and a Fleet Air Arm type of indicator unit."

A fair number of Liberator V, but not all, which were fitted with centimetric radar of various types also had a Yagi aerial of ASV.II in the upper part of the nose glazing. That was the location of the receiving aerial of ASV.II fitted to Liberator III (before transmit /receive modules allowed its deletion). Elsewhere in the 311 book it notes this aerial was required for "landing approach". So I now wonder if this was an indication of an aircraft fitted with "Greenbottle".

 

[WATU]

The Greenbottle information is interesting. It certainly gets mentioned in the monthly progress reports. I will check them out a bit later and post again. Off hand I cannot recall any crew accounts mentioning it but I might have missed such references which I am sure would be rare.

 

[WATU]

Summary of Greenbottle trials and fitting based on Coastal Command Monthly Progress Reports.
Aug 43 Design finalised
Sept 43 Plan to equip all Libs and Leigh Light Wellingtons.
Oct 43 Wellington trials in hand with two sets. Then 50 followed by 250 if 50 successful.
Nov 43 Wellington LL 407 sqn fitted (of 5 LL sqns). Lib LR awaiting prototyping.
Jan 44 Lib now low priority.
Mar 44 407 sqn had it removed then re-installed.
Apr 44 Proposal to fit Wellington LL sqns 179, 304 and 172 sqns. Liberators - required on all LR aircraft. VLR aircraft to have trial installation.
May 44 Wellington - still only 407, plan to fit other Wellingtons cancelled. Liberator LR - no requirement. VLR - 59 sqn to be fitted.
Nov 44 All requirements cancelled.

 

[WATU]

There is a lot on these devices in the minutes of the Scientific Equipment Progress Committee meetings. The problem is that there were a lot of meetings and the TNA records probably spread over 15/20 files not in a neat sequence making it a grind to work though.