DH Mosquito tail fairing - Monica or signal light?

[Dave Swindell]

Until this morning I had always understood that the fairing seen under the tailcone aft of the tailwheel on a lot of Mosquitos was connected with Monica tail warning radar.

In the books I have that reference this fairing it's always referred to as such.

But this morning, @Anthony in NZ made a comment in @Crimea River's build thread stating it was beleived to be a fairing for a Type F Equipment Transmitter:-

Anthony's build thread linked from the post above shows this to be a lamp attached to a flasher unit, something I'd never heard of before but apparently is the conclusion Avspecs and Ferrymead Aero (both  in NZ) have come to from studying mod sheets.

So are they right?

Is it nothing to do with Monica?

Or is the light something completely different in a similar or re-purposed Monica fairing?

I'd be very interested in which mods are being referenced, what date they originated and from which authority (is this an NZ air force mod for example?)

 

Anthony brings up two other possibilities for the fairing, namely Gee and Rebecca, I've not seen these referred to in relation to this fairing and think both highly unlikely

There are published installation diagrams for Gee in the Mosquito, these involve either large (40") whip aerials on the rear canopy or fuselage just behind the canopy, or large internal aerials in the rear fuselage. Gee was a long range navigation system, and required large aerials to be effective at these ranges, a small(ish) fairing wouldn't cover anything remotely useful in this department.

Again, Rebecca has published installation diagrams, and for the Mosquito involved a series of widely spaced dipoles on the wings. Rebecca was used for homing on other radio equipment (initially specifically Eureka devices, but later other devices including airfield homing beacons), if you're homing on something you want it forward facing, putting it pointing out of the back is the last place to install it!

 

Monica was developed during 1942 by the Bomber Support Developement Unit as a tail warning radar unit for bombers to warn of approaching night fighters, installation in aircraft began in 1943. After discovery in july 44 that Luftwaffe Flensburg radar could track Monica, it's use in Bomber Command was stopped. During the period it was in use it was under constant development.

 

Because of it's location under the tail, the fairing is generally not well photographed, however I have (somewhere) a photo that clearly shows what appears to be a dark (black?) radome behind what is generally termed as the fairing, which is usually portrayed as having a vertical open rear. There are a few photos that show the tailcone immediately behind this fairing to be concave, as for the fairing with the light in.

I've always thought that this was a case of "fitted for Monica" with the empty, concave void and "fitted with Monica" with the radome behind the fairing, or possibly two different types of antenna, one in a radome and one without behind the fairing.

 

Looking at photo's where it's possible to determine whether there is a fairing present or not:-

None appear before 1943

None are fitted to FII, NFII, BIV, any PR or Trainers

FBVI's appear to be universally fitted with them, later BIX's and bombers onwards appear to all have them, as do Night fighters from NFXII onwards, FBXVIII's had them, Coastal Command and 100 Group Special Duties Squadrons had them.

 

B Mk 25's built in Canada appear to have the empty fairing and a small Yagi aerial mounted on the tip of the tail cone in place of one of the tail lights. This is also noted as Monica, but this style of aerial in this position isn't visible in other marks, so could this be the use of Canadian or American equipment that required different mounting (they had locally produced radio equipment as well), or just different local manufacturiing practice?

 

It would appear therefore that Mosquitos built after 1942 for use at night or at low/medium altitude over enemy occupied Europe would have the fairing, those that operated in daylight at high altitude (PR) or only over the UK (trainers) didn't.

 

Since this newly discovered "Signalling Light" pointed aft and slightly downward into the crew's main blind spot, I can't think of what use it would be, either at night or at low level - however it would be the logical place for tail warning radar and would be most needed at night or low level when there would be limited visual warning of attack.

 

Please discuss - I'm off to trawl through a load more photos...

[Graham Boak]

Resin lights?  There was a considerable discussion about these, and that they were used to identify other RAF aircraft at night.  However I don't recall any identification with a fitting as you describe.

[Anthony in NZ]

Hi guys, yes this has always been an interesting one for me too!

 

Graham, I think you might be referring to the rearwards resin ones on the wingtips?

 

Dave, I agree mate, GEE or Rebecca were quickly dismissed.  I sometimes wonder if you are correct that 'initially' the fairing was used for Monica (as I have seen photo's of the rear half of that fairing with rearward looking fairing and the aircraft serial with /G after it, denoting guard the aircraft).  Maybe unsuccessful and the fairing was repurposed?  The wiring throughout HR339's remains, and TE758's fuselage match up with the Mod sheets indicating this Type F flasher unit fitted as in Tony's HJ711.

 

Great discussion

[Crimea River]

Very glad you brought this up Dave as I was going to do so as well. I've always though the installation to be for Monica as well until Anthony posted that in my build thread. Light or not, I was not aware that the fairing was accompanied by a hollow-out of the tail cone and a closer look at my reference photos shows this to be the case.

 

As you said, photos are hard to come by as the area is mostly hidden in ground shots and aerial shots are typically too far away and grainy. Here's one I've found and cropped. The photo is from the Gordon Permann collection and is labelled as an FB VI, though the bulged bomb bay nullifies that assertion. Note also the fuel cooler under the starboard wing root.

 

 

To my eye, there is no light in this picture but that doesn't eliminate the possibility that one may have been there previously that was since removed.

 

Very interested to hear from others and would very much like to see more info about this little-known (to me) area, including diagrams from the noted mod sheets.

 

Andy

[Anthony in NZ]

Nice angle there Andy!

I have some good images, but Photobucket has stopped working again!  Wasn't that money well spent LOL

[Jure Miljevic]

I understand Monica had been installed on Mosquito on experimental but not on regular bases. The reasoning was that not many Luftwaffe aircraft could have caught Mosquito anyway so why bother. Will try to find a source for that. Cheers

Jure

[Anthony in NZ]

2 hours ago, Jure Miljevic said:

I understand Monica had been installed on Mosquito on experimental but not on regular bases. The reasoning was that not many Luftwaffe aircraft could have caught Mosquito anyway so why bother. Will try to find a source for that. Cheers

Jure

Jure, that would make perfect sense.  That might explain the airframe with /G on it during trials. But due to a non requirement.... latterly just left empty or blanked off as I had heard. Then became useful later on to position the F Type unit?

Edited December 31, 2019 by Anthony in NZ

[Wez]

11 hours ago, Dave Swindell said:

Anthony brings up two other possibilities for the fairing, namely Gee and Rebecca, I've not seen these referred to in relation to this fairing and think both highly unlikely

There are published installation diagrams for Gee in the Mosquito, these involve either large (40") whip aerials on the rear canopy or fuselage just behind the canopy, or large internal aerials in the rear fuselage. Gee was a long range navigation system, and required large aerials to be effective at these ranges, a small(ish) fairing wouldn't cover anything remotely useful in this department.

Again, Rebecca has published installation diagrams, and for the Mosquito involved a series of widely spaced dipoles on the wings. Rebecca was used for homing on other radio equipment (initially specifically Eureka devices, but later other devices including airfield homing beacons), if you're homing on something you want it forward facing, putting it pointing out of the back is the last place to install it!

 

Monica was developed during 1942 by the Bomber Support Developement Unit as a tail warning radar unit for bombers to warn of approaching night fighters, installation in aircraft began in 1943. After discovery in july 44 that Luftwaffe Flensburg radar could track Monica, it's use in Bomber Command was stopped. During the period it was in use it was under constant development.

Dave,

 

You're correct in your dismissal of both Gee and Rebecca for this fairing.  Gee was a long wavelength parabolic navigation system, it therefore needed a relatively long aerial to be picked up by the receiving aircraft.  Likewise, Rebecca being a homing system needs at least two aerials some distance apart, the signal being received in one aerial before the other, the system detecting a phase difference between the signals which is resolved into a bearing to follow to the ground-based transmitter.

 

Monica, being a radar detection only needed a small antenna because radar frequencies have a relatively small wavelength.  In Martin Streetly's Confound and Destroy, the Monica aerial fitted to 100 Group Fortresses and Mosquito's as a small, arrow head antenna similar to but not the same as the original AI Mk.IV aerials.  It's horizontally orientated and sits under the immediate tip of the fuselage (e.g. between the fairing being discussed and the tip of the empennage).

 

Therefore, I'm thinking the fairing had a different use, the Type F flasher unit?  A fairing would shield the lamps from being seen in all but a very specific direction.

3 hours ago, Jure Miljevic said:

I understand Monica had been installed on Mosquito on experimental but not on regular bases. The reasoning was that not many Luftwaffe aircraft could have caught Mosquito anyway so why bother. Will try to find a source for that. Cheers

Jure

As Dave has stated and for the reasons stated, Monica was removed from general Bomber Command use however, it was retained on 100 Group Mosquito's to lure German night-fighters towards the Mosquito's, once in range the Mosquito would turn off Monica, turn behind the German night-fighter and destroy it.  A case of poacher turned gamekeeper.

 

Quite why 100 Group's Fortresses retained Monica I'm not sure (sounds like a good excuse to read both Confound and Destroy and Confounding the Reich again), unless it was to lure as many German night-fighters onto them and then jam their radars thus tying up assets, wasting their fuel and rendering them useless.

Edited December 31, 2019 by Wez
speelung

[Anthony in NZ]

Better be quick, Photobucket is working...

The rectangular panel on the armor plate is where the Flasher unit went

 

Ugh...It stopped working again  This is a Std Motors built TE910/ NZ2336

 

I will post again when I can

 

[Jure Miljevic]

Hello

It seems that Monica equipped Mosquitos flew fairly late in the war and almost exclusively in bomber support role. In his book The de Havilland Mosquito (Arco) M. J. Hardy mentions that: ˝Some NF XIXs of No 85 and 157 Squadrons with American radar were fitted with the Monica I and later Monica VI rearward-looking radar, installed ahead of the pilot, for use over Europe in the bomber-support role ...˝, and the same is stated for some of the Mosquitos of NF Mk.XXX version. US SCR 720/729 equipped No 85 and 157 Sqn. Mosquitos received Monica in May 1944. BSDU experimented with ˝installation of Monica llle in Mosquito FB VI NT181, this set also being fitted in a forward-looking position in the hope of producing an accurate ranging radar for use against the V-ls.˝. Some bomber-supporting FB Mk.VIs had also been fitted with Monica. According to Hardy, the only exception to bomber-support rule seems to be a number of Monica equpped B Mk.XVI path-finders.

˝Rearward-looking˝ and ˝Ahead of the pilot˝ combination sounds quite puzzling and I browsed through my books and the web and looked for suitable photos. I had no luck, but in Richard A. Franks' book The de Havilland Mosquito (SAM) I found a sketch of SCR 720/729 radar installation, which also included a sketch of Monica radar, installed in a small fairing under the tail cone as shown on the photo that Crimea River posted. The sketch seems to be copied from 406 Sqn. MM474/G NF.XXX photo, which shows the installation very clearly and had been published in Stuart Howe's The de Havilland mosquito - an illustrated history (Aston). Unfortunately, I was not able to find the photo on the web. Cheers

Jure

[Crimea River]

Thanks Jure, I'll go back and see if I have those references.

 

8 hours ago, Anthony in NZ said:

Better be quick, Photobucket is working...

The rectangular panel on the armor plate is where the Flasher unit went

 

Ugh...It stopped working again  This is a Std Motors built TE910/ NZ2336

 

I will post again when I can

 

 

I have seen that bracket several times in other photos and went back to my copy of a Swedish NF XIX Illustrated Parts Manual. In there, the part is called up as "Plate, Flasher Mounting" and is given a part number S981555A so score another point for the flasher idea.

 

It seems plausible to think that the flasher mod in the tail cone made for a convenient mount for the later Monica installation and that the detail ultimately served a dual purpose.

Edited December 31, 2019 by Crimea River

[Crimea River]

More on this, and it's looking more like the detail was for a flasher lamp. I went into more detail in my above referenced Illustrated Parts Catalogue (funny how one glosses over things that one isn't really looking for) and found the attached excerpts showing the parts breakout for the NF XIX tail cone. Note that the descriptions of parts 41 and 42 are "Fairing, Lamp, Front Portion" and "Fairing, Lamp Rear Portion", respectively

 

[Dave Swindell]

Thanks for all the interest in this chaps, and I'll respond in a minute, but first a teaser -

Spoiler

This morning I found some info which suggests we're talking about two different bits of equipment, and the lamp is not associated with the fairing.

 

20 hours ago, Graham Boak said:

Resin lights?  There was a considerable discussion about these, and that they were used to identify other RAF aircraft at night. 

I think you're in the ballpark there, Graham, but not in the fairing.

19 hours ago, Anthony in NZ said:

Graham, I think you might be referring to the rearwards resin ones on the wingtips?

He is, typical on bombers like the Lancaster, but where was the equivalent on the Mosquito?

19 hours ago, Anthony in NZ said:

The wiring throughout HR339's remains, and TE758's fuselage match up with the Mod sheets indicating this Type F flasher unit fitted as in Tony's HJ711.

HR339 and TE758 I can understand, as these were built as FBVI'sand would almost certainly have left the factory (Standard Motors in both cases) with the fairing.

HJ711, however, was a Hatfield built FII and I haven't (as yet) found photo's of FII's with the fairing.

So, if HJ711 wasn't built with the fairing and is now fitted with the Type F flasher unit, either the flasher unit has nothing to do with the fairing, or it was retrofitte at some later date.

19 hours ago, Crimea River said:

I was not aware that the fairing was accompanied by a hollow-out of the tail cone and a closer look at my reference photos shows this to be the case.

There's a few photo's of Mosquito's banking away from the camera where the lighting clearly shows the fuselage behid the fairing to be concave. There's a good one of FBVI RS525 NE*D (that I can't find at the mo) and this one of an FBXVIII

 

19 hours ago, Crimea River said:

The photo is from the Gordon Permann collection and is labelled as an FB VI, though the bulged bomb bay nullifies that assertion.

That's a BXVI, ML932 8K*K, if you look at the collection there's a series of shots of her and the replacement panel over the port nacelle is clearly visible in the shot you've posted. The other shots show that the sspace behind the fairing is empty, so we're looking pretty much directly into the space inside it. There does appear to be something in there, but the resolution isn't good enough to say what.

14 hours ago, Jure Miljevic said:

I understand Monica had been installed on Mosquito on experimental but not on regular bases.

Martin Streetley in "Aircraft of 100 Group" states some type of Monica (there were several versions) was fitted to all 100 Group Mosquito Interceptors, 16 squadrons and various marks. It was widely fitted and regularly used., even outside 100 Group.

Dorothy, a BIX ML897 D of 1409 (Met) flight that I've been researching and started building was fitted with Monica, as F/O Baker's flight logs show 3 Monica flight tests, the last being 14th June 1944, just a month before the Flensburg connection was made.

11 hours ago, Wez said:

it was retained on 100 Group Mosquito's to lure German night-fighters towards the Mosquito's, once in range the Mosquito would turn off Monica, turn behind the German night-fighter and destroy it.

The Whiting manouvre, I didn't post this originally to avoid too long a post, thanks for bringing it up, Wez.

11 hours ago, Wez said:

In Martin Streetly's Confound and Destroy, the Monica aerial fitted to 100 Group Fortresses and Mosquito's as a small, arrow head antenna similar to but not the same as the original AI Mk.IV aerials.  It's horizontally orientated and sits under the immediate tip of the fuselage

Did you find a photo of a Monica aerial on a Mosquito in C&D? I've looked (twice!) but could only find drawings showing it on the tip of the tailcone on profiles. It is possible it was here, but I've not found evidence. As previously mentioned, the Canadian Mk25's had a Yagi (not arrowhead) aerial mounted in the vertical plane here, this has also been noted as Monica.

11 hours ago, Wez said:

Quite why 100 Group's Fortresses retained Monica I'm not sure (sounds like a good excuse to read both Confound and Destroy and Confounding the Reich again), unless it was to lure as many German night-fighters onto them

Streetly, C&D Chapter 5, eg December 44 AI Mk X/Monica (85 & 157 sqns) 15 Monica contacts, 6 of which converted to AI contacts - presumably by use of the Whiting manouvre or similar.

3 hours ago, Jure Miljevic said:

It seems that Monica equipped Mosquitos flew fairly late in the war

First used operationally 19/20 June 1943 (Streetly C&D p166)

3 hours ago, Jure Miljevic said:

According to Hardy, the only exception to bomber-support rule seems to be a number of Monica equpped B Mk.XVI path-finders.

Not correct, see above ref Dorothy

3 hours ago, Jure Miljevic said:

˝Rearward-looking˝ and ˝Ahead of the pilot˝ combination sounds quite puzzling

Not really, the aerial was mounted in the tail looking to the rear, the display was ahead of the pilot, or to be more accurate on the pilot's side of the Nav/radar operators panel. It was a small circular display approx 3" dia in a square panel.

3 hours ago, Jure Miljevic said:

The sketch seems to be copied from 406 Sqn. MM474/G NF.XXX photo, which shows the installation very clearly and had been published in Stuart Howe's The de Havilland mosquito - an illustrated history (Aston).

That's the photo I've been looking for, page 61. The photo below of NF36 RL152 shows the usual style of fairing without the drak cover behind it, where it is again referred to as Monica.

10 hours ago, Anthony in NZ said:

The rectangular panel on the armor plate is where the Flasher unit went

Yes, I've found this unit in cockpit equipment drawings for both NF 30 and B35's (but not FII's or FBVI's), but the big questions are what does it do and what is it connected to?

It's referred to as a type F flasher unit, and "Agile" commented on Anthony's proboard build that it was connected to a type F transmitter unit in the tail. I've subsequently found a type F switching  and indicator unit mounted on the starboard cockpit side adjacent to the Nav's elbow on cockpit drawings of both the B35 and NF30 (which also show the flasher unit) I'm going to make a bold leap and assume that the switching unit controls the flasher, which in turn controls the transmitter. The breakthrough I had this morning though was with a couple of diagrams in Streetly Aircraft of 100 Group showing equipment layouts  for a 23 Sqn ASH equipped FBVI, and an 85 Sqn  NF30. Both show the Monica aerial, and both show the type F transmitter. The type F transmitter is mounted in both cases in the tailcone in place of the lower tail light (clearly not in the fairing). I say transmitter, it's actually labelled as Infra Red source (for type F or Z id system) Both diagrams also show and infra red telescope (for type F or Z id system) protruding through (or more likely just behind) the armoured windscreen in front of the Nav/radar operator.

This to me is a strong indication that the type F equipment is for nighttime IFF, and I'd presume that the flasher unit is for generating an identifiable signal (eg morse letter of the night) or similar to differentiate from possible enemy IR transmissions. As there is a sight fitted for the Nav to id friendly "targets" this must tie in to general use in bomber command of similar IR transmitting devices, which is what I believe @Graham Boak was referring to with his reference to resin wingtip lamps - IIRC these are infra red devices, and of a similar size to a tail light rather than the much larger ID light that was shown in the proboard thread. I'm aware that late war there were larger IR devices fitted in the front of bombers to counter "Village Inn" AGL radar locking on to following bombers, but this isn't really relevant to night fighters as their attack profile was invarialbly from the stern.

 

If I'm correct on the use of the type F, this would be pretty useless in daylight; so why then are the fairings pretty much universally fitted to Coastal Command Mosquitos which operated predominantly during daylight hours. As I've surmised above the type F equipment wasn't fitted in the fairing, so something else must have been there that would be useful both at night and during daylight, and the general concensus on that has been Monica.

However the two diagrams that help with type F appear to show the Monica aerial inside the tailcone, forward of the IR source but aft of the fairing position, and more confusingly, the ASH FBVI shows a previously discounted by us Rebecca aerial in the fairing position. This could be a source of the use of the fairing for Rebecca?

Streetly C&D p166 lists 9 different variants of Monica, some with subvariants, and there is an indication that at least with some of the earlier variants, components from other radar devices were used to build the system. It is not unreasonable therfore to think that there was a possibility that a Rebecca aerial unit was used in some versions of Monica. (Rebecca was in developement from 1940, some 3 years before Monica went operational)

 

So to sum up, I'm currently of the opinion that:-

Type F is an IR IFF I/D system mounted in the extreme tail and nothing to do with the fairing under the tailcone

Monica aerials of various sorts could be mounted either in the fairing, behind the fairing in a dome, or on the extreme tip of the tailcone

Rebecca aerials may have been mounted in the fairing, but if so they had been re-purposed for Monica.

1 hour ago, Crimea River said:

More on this, and it's looking more like the detail was for a flasher lamp.

Well thanks Andy, spent all afternoon researching and typing the above and you blow me out of the water seconds before I post, cheers mate😭

Off for my tea and a sulk...

 

Quick edit after tea and a sulk  - @Crimea River Andy, just joshing you, excellent post, just what we need.

Below are the diagrams referred to above for your eddification

Edited December 31, 2019 by Dave Swindell
Tea and a Sulk

[Anthony in NZ]

Great info guys, Andy, I have that illustration on file...thanks for finding it before me!

 

Same airframe, no flasher and its fairing shown here on its wign with no lamp installed.  Seems it was an option only (no flasher-no lamp?)

 

Another original (Photo credit Dag Guest) unrestored

 

Avspecs interpretation which is most likely.  I know Andy there spent a lot of time researching this too.

 

Dave, you have done a stellar job mate, and I still wonder if you are not entirely incorrect, but lamp is what it ended up as.... I think I have an image and drawing of the resin lamp on the rear of the wingtip of the Mosquito....somewhere!

 

Love these discussions

Edited December 31, 2019 by Anthony in NZ

[Dave Swindell]

1 hour ago, Crimea River said:

"Fairing, Lamp, Front Portion" and "Fairing, Lamp Rear Portion"

Thanks for posting the parts drawing Andy, they seem to indicate pretty conclusively that it's a lamp fairing

However, just a thought, if this is from a wartime NFXIX catalogue, and security on radar and the like would be pretty tight, and your parts diagram doesn't include the "lamp", are we sure this isn't an Air Ministry euphemism for those that didn't really need to know what was actually fitted, but had to make or supply said parts?

1 hour ago, Anthony in NZ said:

Another original (Photo credit Dag Guest) unrestored

Great photo's Anthony, especially the unrestored one. I'd assumed that the whole of the tailcone was formed sheet metal, but the photo and the avspecs restored one with the pinked tape reinforcements indicate that the main cone is formed wood with sheet metal fairings and securing plates added.

This is particularly important when you look at the diagrams i've just added to my previous post which appear to show the Monica aerials inside the tailcone - this wouldn't work with a metal cone as this would shield it, but it would work inside a wooden one. Is this why we rarely see Monica aerials in photo's of Mosquito's that should have this fitted?

 

So, if this is a lamp, is it anything to do with the type F system?

Do the Mod sheets explicitly connect a lamp in this position to the flasher unit, or could it be the IR source as per the diagrams above.

If it is, why is it so large and shielded under the tail when you would want a friendly to identify you from above and behind as well as below and behind (which would be possible if positioned in place of a tail light).

Also, why use it on Coastal Command aircraft operating at low level in daylight?

 

If it is a lamp, and nothing to do with the type F system, what was it used for?

 

If it's a "lamp" 😉😉, then we're non the wiser.

 

The Key publishing/Airfix Modelworld Mosquito special has plans credited to Terry Higgins ( @Terry @ Aviaeology ?) ref the fairing they note "Although the system was not installed, the Monica tail warning aerial fairing was present on most (if not all) FBVI's" and I'll add the FBXVIII's to that as well.

Why go to the trouble of fitting these fairings to all these aircraft if they were not being used (especially as PR aircraft were coming of the production line without the fairings)

If Monica was not fitted, was something else there?

Is there any record of type F transmitters, flasher units and switching/indicator units on Coastal Command Mosquitos?

Is it our mystery lamp?

When was type F equipment introduced?

Does this tie in with the introduction of wingtip resin lamps in Bomber Command?

Can anyone from the Bomber Command SIG shed any light on this? @woody37? @general melchett?

So many questions, my head is spinning, i'm off for a lie down..

 

[T-21]

I'am inclined to think this is Village Inn or Automatic Gun Laying . The Mossies could pick up friendly bomber aircraft in the stream. Lancasters had Z equipment in the nose blister of two infra red detectors that were picked up by Lancasters fitted with the AGLT tail radar . A beam was picked up by the leading aircrafts navigator who directed the tail gunner. I agree warrants further investigation but interesting that this is only coming too light now.

[Dave Swindell]

3 minutes ago, T-21 said:

I'am inclined to think this is Village Inn or Automatic Gun Laying

I'd respectfully disagree with that, Village Inn was only fitted in tail turrets and from late 44 onwards, the fairing and equipment we're discussing in this thread appeared on the tails of Mosquitos from about mid 43 onwards, so Village Inn is too late, and facing the wrong way to be picked up by a rear mounted device on the Mosquito. The Navigator had nothing to do with the intercept on production sets, the gunner just followed a blip in the gunsight and fired at the appropriate range. Z equipment directed an infrared beam forward of an aircraft, which was supposed to be detected by Village Inn and interrupt the firing circuit to prevent friendly fire incidents

[Anthony in NZ]

15 minutes ago, Dave Swindell said:

I'd respectfully disagree with that, Village Inn was only fitted in tail turrets and from late 44 onwards, the fairing and equipment we're discussing in this thread appeared on the tails of Mosquitos from about mid 43 onwards, so Village Inn is too late, and facing the wrong way to be picked up by a rear mounted device on the Mosquito. The Navigator had nothing to do with the intercept on production sets, the gunner just followed a blip in the gunsight and fired at the appropriate range. Z equipment directed an infrared beam forward of an aircraft, which was supposed to be detected by Village Inn and interrupt the firing circuit to prevent friendly fire incidents

This raises another interesting question.  The owner of TE910 (who has just recently passed R.I.P) got talking to me about the Mosquito's fitted with 'Z' equipment and the use of this infra red beam.  He was very knowledgeable on Mosquitoes  and started talking about this to me.  At the time it was all new information to me and so was not making a lot of sense, but he was adamant so I just nodded in agreement.  But he was telling me that the lamp in the starboard wing leading edge (which I always assumed was another landing lamp) was where this beam came from.  I wish I could go back and discuss it further with him. I have not really looked much into this, but maybe these late build airframes had provision for 'Z' equipment?

 

Sorry, back to the tail LOL

[Dave Swindell]

30 minutes ago, Anthony in NZ said:

But he was telling me that the lamp in the starboard wing leading edge (which I always assumed was another landing lamp) was where this beam came from. 

Again, new info to me too, but entirely logical if you're creeping up behind targets at night over Germany you don't want the first indication that the target is friendly to be a burst of fire from a Village Inn turret. There's photos of Z transmitters in the bomb aiming blisters of 100 Group Lancasters and Fortresses, so they were aware of the problem and were installing a solution. The nose on the Mosquitos was full of radar, so why not in the wing leading edge?

[Anthony in NZ]

51 minutes ago, Dave Swindell said:

Again, new info to me too, but entirely logical if you're creeping up behind targets at night over Germany you don't want the first indication that the target is friendly to be a burst of fire from a Village Inn turret. There's photos of Z transmitters in the bomb aiming blisters of 100 Group Lancasters and Fortresses, so they were aware of the problem and were installing a solution. The nose on the Mosquitos was full of radar, so why not in the wing leading edge?

Yes totally makes sense to me now, what he was telling me at the time.  Possibly not actually fitted to export airframes?  But I have to research the 'Z' equipment now also!

[Jure Miljevic]

Hello

Here is another information about Mosquito night fighters which is, at least to me, totally new. In his book De Havilland mosquito (Crowood) Martin Bowman claims that AI Mk.IV equipped Mosquitos had 360° scanning ability and were able to detect aircraft approaching from astern. With such arrangement, there was no need for tail warning radar until more powerful centimetric AI Mk.X (SCR 720/729) radar arrived. Its dish antenna had no ability to scan aft hemisphere so to remedy this deficiency Monica rear warning radar had been installed. Cheers

Jure

[Wez]

17 hours ago, Dave Swindell said:

Did you find a photo of a Monica aerial on a Mosquito in C&D? I've looked (twice!) but could only find drawings showing it on the tip of the tailcone on profiles. It is possible it was here, but I've not found evidence. As previously mentioned, the Canadian Mk25's had a Yagi (not arrowhead) aerial mounted in the vertical plane here, this has also been noted as Monica.

14 hours ago, Dave Swindell said:

This is particularly important when you look at the diagrams i've just added to my previous post which appear to show the Monica aerials inside the tailcone - this wouldn't work with a metal cone as this would shield it, but it would work inside a wooden one. Is this why we rarely see Monica aerials in photo's of Mosquito's that should have this fitted?

 

 

No, I never found a picture of a Mosquito with the arrowhead Monica aerial fitted in C&D (Streetly), nor in Confounding the Reich (Bowman & Cushing), 100 Group (Bowman), Even When the Sparrows are Walking (Brettingham).  The last three all have some very clear photos of the tail areas of Mosquitoes from the period 1944-1945.

 

There is a very good picture of the Monica aerial on a Fortress in the Brettingham book, looking at that now I'd have to say that I'm now convinced that the arrowhead Monica aerial was based on the AI Mk.IV transmitter aerial and was fitted offset from the centreline to starboard.  I wonder if Streetly, having found that Monica was fitted to the Mosquito has put 2 & 2 together and assumed that the Monica aerial was fitted in the same fashion as the Fortress whereas, you make a very valid point, the Monica aerial could be fitted internally to the Mosquito as wood is dielectric, the radar signal would pass through it whilst on the metal construction of the Fortress it wouldn't thus forcing it to be mounted externally.

 

17 hours ago, Dave Swindell said:

If I'm correct on the use of the type F, this would be pretty useless in daylight; so why then are the fairings pretty much universally fitted to Coastal Command Mosquitos which operated predominantly during daylight hours. As I've surmised above the type F equipment wasn't fitted in the fairing, so something else must have been there that would be useful both at night and during daylight, and the general concensus on that has been Monica.

 

Simply because the tailcones are built to a pattern and fitted to whichever aircraft received them, that aircraft could be a bomber, night-fighter or PR aircraft.  If you think about it, wartime production would be streamlined to remove as many variations as possible, it was probably introduced as a modification for bomber versions but all Mosquitoes after a certain point got it whether they needed it or not. 

 

17 hours ago, Dave Swindell said:

Rebecca aerial in the fairing position. This could be a source of the use of the fairing for Rebecca?

Streetly C&D p166 lists 9 different variants of Monica, some with subvariants, and there is an indication that at least with some of the earlier variants, components from other radar devices were used to build the system. It is not unreasonable therfore to think that there was a possibility that a Rebecca aerial unit was used in some versions of Monica. (Rebecca was in developement from 1940, some 3 years before Monica went operational)

 

 

No Rebecca is a homing system, for homers to work you need two separate antenna some distance apart, the minimum distance they should be from each other is a function of wavelength, Rebecca used dipole aerials mounted either side of the aircraft.  There is a good description of how Rebecca worked here, if you do a Google Image search for Rebecca Navigation System Aerials you get plenty of hits showing the Rebecca aerials on the 4 engine bombers.

 

As I described in my initial post, being a homing system, Rebecca needs at least two aerials some distance apart, the signal being received in one aerial before the other, the system detecting a phase difference between the signals which is resolved into a bearing to follow to the ground-based transmitter, this small fairing mounted on the centreline would not provide sufficient separation between the aerials, also, looking at the images of the larger aircraft installations the aerials are quite large because of the band the system works in (each half dipole would be 0.7m/27.5 inches).

 

I don't believe the fairing has anything to do with Rebecca.

 

14 hours ago, Dave Swindell said:

Thanks for posting the parts drawing Andy, they seem to indicate pretty conclusively that it's a lamp fairing

However, just a thought, if this is from a wartime NFXIX catalogue, and security on radar and the like would be pretty tight, and your parts diagram doesn't include the "lamp", are we sure this isn't an Air Ministry euphemism for those that didn't really need to know what was actually fitted, but had to make or supply said parts?

 

Sorry, but the Illustrated Parts Catelogue (IPC) is intended for those maintaining the aircraft, they would already be security cleared, there would be no point using euphemisms to describe the system, in fact it would only cause confusion. 

 

Additionally, Monica was a probably Service Radio Installation Modification (SRIM), it would be covered by its own documentation detailing installation procedure and parts list with associated drawings, the SRIM detail would not be included in the basic aircraft IPC.  If the IPC says it's for a lamp then that's what its original design purpose is.

17 hours ago, Dave Swindell said:

So to sum up, I'm currently of the opinion that:-

Type F is an IR IFF I/D system mounted in the extreme tail and nothing to do with the fairing under the tailcone

Monica aerials of various sorts could be mounted either in the fairing, behind the fairing in a dome, or on the extreme tip of the tailcone

Rebecca aerials may have been mounted in the fairing, but if so they had been re-purposed for Monica.

 

I don't believe the faring has anything to do with Rebecca (see above), I likewise don't believe it was used for Monica either, looking at the size of the Monica aerial fitted the 100 Group Fortresses, the aerial is just too big to fit in the fairing, it could however, serve as a useful mount for an externally mounted aerial that we haven't found any evidence for...   ...yet, I've only consulted my 100 Group references, I haven't begun to trawl through my Mosquito references (mainly because I don't have the time right now).

 

All of this discussion is interesting but we should remember, there are basic engineering principles here (aerial size, placement and systems principals of operation), and the way the RAF carry out modifications to aircraft and how that documentation sits outside of the basic aircraft document set.

Edited January 1, 2020 by Wez

[EwenS]

8 hours ago, Jure Miljevic said:

Hello

Here is another information about Mosquito night fighters which is, at least to me, totally new. In his book De Havilland mosquito (Crowood) Martin Bowman claims that AI Mk.IV equipped Mosquitos had 360° scanning ability and were able to detect aircraft approaching from astern. With such arrangement, there was no need for tail warning radar until more powerful centimetric AI Mk.X (SCR 720/729) radar arrived. Its dish antenna had no ability to scan aft hemisphere so to remedy this deficiency Monica rear warning radar had been installed. Cheers

Jure

I think that this might be a simplified description of how the Serrate equipped Beaufighters and Mosquito Mk.II operated. This wasn’t a defensive system but an offensive one.

 

AIUI Serrate was a passive detector of the German Lichtenstein AI Radar. It was able to give a bearing (implying 360 degree coverage) on the German radar in the British night fighter at a range of up to 100 miles. Our NF would then fly along the bearing and use its AI Mk.IV at much shorter range to detect the German aircraft and attack it. More info here

 

https://masterbombercraig.wordpress.com/avro-lancaster-bomber/avro-lancaster-marks/safety-equipment/serrate-radar/

 

 

[T-21]

In Martin Streetleys Mosquito NF.30 cutaway HH is also shown as Z i/d system . This is an IFF system Z equipment using infra red beams to detect if an aircraft  was friendly approaching from behind.  Lancasters had the two detectors in the two rings in the bomb aimers Perspex blister on Lancasters. We need evidence of Z equipment in the leading edges of DH Mosquito aircraft ? 

 

A mention of Z equipment here  https://mraths.org.uk/?page_id=480               https://military.wikia.org/wiki/List_of_World_War_II_electronic_warfare_equipment

Edited January 1, 2020 by T-21

[T-21]

Page 134  The Aircraft of 100 Group by Martin Streetly  under the IFF paragraph. " The problem of aerial identification was one which taxed 100 Group for much of its operational life and towards the end of the war,an infra red system was introduced. This comprised the installation of an IR source  in the tails of the Group's aircraft and in  the Mosquito squadrons ,a cockpit mounted sight 3 inch in diameter and 14 inch long which showed a green spot when viewing a friendly source".

 

Does anybody have a picture of a Mossie cockpit or pilots notes showing this ?