ASV radar

[expositor]

Have questions about said radar.  Looking at photos of yagi-equipped a/c, some have obvious transmitters; assuming the yagis are receivers, and some don' t.  For example, the Fairey Swordfish has an obvious transmitter antenna in the upper wing center section, but single engine USN planes like the SBD and TBF/M don't have an obvious transmitter.  RAF B-24s also have a nose yagi, the USN planes don't, assuming the array on the rear fuselage sides of many early Pacific theatre a/c are the transmitters. Further confusing photos, to me anyway, are those PB4Ys with, again what I believe are transmitting fuselage antennas, but without any wing yagi antennas, with only what I thought were small homing antennas, and so, no receiver...?  I can only assume that the ventral scanner as in the UK based patrol bombers was a detriment to defensive armament in the Pacific. 

One online site I found discused the different ASV radars, but was not specific as to the early sets used by the USN which dispensed with the dorsal arrays.

Later PB4Ys have various mini yagis on the lower forward fuselage, in various places, again begging the question as to the location of the complimentary antenna, unless those yagis transmitted and received.

So, can anyone help?

Thanks!!!

Edited December 6, 2019 by expositor
Spelling

[dogsbody]

Some Swordfish had aerials mounted on the forward outboard struts.

 

 

 

 

Chris

[John Aero]

Radars are either Active or Passive.  Active Radars generate their own RF (Radio Frequencey), which they transmit out to a target in pulses and they collect and analyze the reflected pulses enabling such data as Range and Azimuth  to be gathered.

 

Passive radars are basically collectors of RF, in simple terms they detect Radar signals looking at you.  Early radars such as ASV used quite low frequencies and used Yagi type RX aerials such as the early Stickle back antennae often with single blade Tx aerials or directional arrays to fix the targets position.

 

With the invention of reliable Magnetrons and higher frequency Waveguide systems for Active Radars the units became fairly self contained and so the aerials became highly focused dish type scanners as part of a transceiver and they could be housed in a protective Radome or dielectric panel in the nose or under the belly.   Perspex was one of the few early dielectrics available and that is why the Radomes on early Mosquito's and Lanc's etc were partially see through.

 

Radar is a study in it's own right and I've forgotten 99.9% of what I once knew about Air Radar such as GEE.2 and H, Rebecca Mk.4, SARAH and Orange Putter. The reason that the fin of the Canberra is made of wood is because it contained the GEE H aerial...

A.S.V is Air to Surface Vessel. H.2S showed a rough picture of the ground below and ahead. GEE was a Radar which analyzed signals from several ground stations to compute your position quite accurately and the later H addition was a clockwork bombing run-in facility called the Mouse and it was placed in such a position that the NAV could kick it if it didn't work properly.

 

John

 

 

[EwenS]

Expositor

Now you have opened a real can of worms! After 40 years of study I’m still learning new stuff about radar installations in British aircraft let alone those in US types. To add to the complications aerial arrays for the early ASV.II changed over time and between aircraft types and, despite having been introduced in early 1941, it was still in service in 1945. I don’t guarantee that what follows is 100% accurate given the complexity of the subject but it will give you a starting point for further research.

 

The US sets are a bit better documented. Try here for details of them.

https://www.history.navy.mil/research/library/online-reading-room/title-list-alphabetically/u/operational-characteristics-of-radar-classified-by-tactical-application.html#asv

 

As far as the UK is concerned the first ASV radar was the ASV.I set that came into service in limited quantities (c50 sets) in 1940 mainly on Hudson, Sunderland and Catalina aircraft. It operated on the 1.5m wavelength.

ASV.II followed in early 1941 with better electronics and range and was fitted to a multitude of RAF & RN aircraft types. There is a 1945 Manual for this set in the Australian Archives which helps explain its aerial configurations (Chapter 6 on page 56) and operation (Chapter 7). The set-up described for the RAAF Beaufort seems to me to be the one that reads across into most RAF/RN types the best.

https://recordsearch.naa.gov.au/SearchNRetrieve/Interface/ViewImage.aspx?B=1351313

 

The first ASV.II aerial configuration to consider is the forward looking or “Homing” Yagi aerial configuration fitted to all aircraft carrying this radar. It normally featured a single transmit aerial in the nose and a receiving aerial under each wing angled out by 20-45 degrees from the airframe centreline. One exception was the Fairey Albacore which had 2 transmit aerials angled out low on the fuselage sides. The Swordfish had a transmit aerial attached to the upper mainplane as you have noted.

 

The second aerial array was the sideways looking “Search” array fitted to larger aircraft such as the Liberator, Fortress and Wellington. This had a transmitter array or four aerials along the spine of the aircraft and two rows of four receiver aerials along each side of the aircraft. This gave longer detection range. This was used to search for a target then, when something was found, the aircraft would turn and use the shorter range forward looking Yagi array to home in on it for an attack.

 

Now for the complication. As radar developed, the sets were fitted with transmit / receive units internally that allowed each aerial to both transmit a radar signal and detect the returning radar echo. At that point the transmitter aerials under the nose (“Homing” array) and along the spine of the larger aircraft (“Search” array) could be removed so reducing drag. So when, for example, you look at a Barracuda II fitted with ASV.IIN it only has the wing aerials. This happened about late 1942 / early 1943.

 

Another complication concerns the aerial arrays fitted to Coastal Command Flying Fortresses. These initially had a different fuselage search array (see US ref above), and later all 3 Yagi forward looking aerials were concentrated on the nose (as per the Anson setup in the RAAF Manual). See Rob Stitt’s “Boeing B-17 Flying Fortress in RAF Coastal Command Service” for more details.

 

After the Mark II ASV sets moved to centimetric wavelengths with radar scanners in bulges in the nose or under the fuselage or, in the case of Fortress Mk.III and Liberator VI/VIII, in retractable radomes.

In summary there were the following ASV sets in British use.

 

 

ASV Mark

Wavelength

Notes

I

1.5m

Short range. Aerials were short dipoles extended from fuselage sides (see Hudson set up in RAAF Manual)

II

1.5m

Referred to as Long Range ASV see above

IIA

1.5m

Higher powered Mk.II but according to Wiki was only fitted in 6 Sunderlands

IIB

1.5m

SCR521/ASE US equivalent of Mk.II

IIN

1.5m

Mk.II adapted for the RN

II Spec

50cm

US ASB similar to Mk.II with moveable antenna

 

 

 

III

10cm

ASV version of Bomber Command H2S. In service from beginning of 1943

IIIA

10cm

Improved Mk.III with Lucero

IIIB

10cm

Mk.IIIA with range finder for Leigh Light aircraft

IIIC

10cm

Mk.IIIB with Fishpond

 

 

 

IV

10cm

Canadian DMS/1000 fitted to Liberators only in 1943 in “Dumbo nose” chin radome

 

 

 

V

10cm

US ASG-1 introduced May 1943 on Liberators in “Dumbo nose” chin radome

VA

10cm

US ASG-3 or AN/APS-2 from 1944 in ventral radome in place of belly turret

 

 

 

VI

10cm

High power Mk.III prototype early 1944 for Leigh Light Wellingtons

VIA

10cm

Mk.VI with auto-lock and follow for Wellington XIV

VIB

10cm

Mk.VI main production standard version

VIC

10cm

Mk.VIB adapted for Sunderland V with split scanners under wingtips

 

 

 

VII

3cm

British development of MK.III

 

 

 

VIII

3cm

US ASD equivalent of Mk.VII fitted in Catalinas and Venturas

VIIIA

3cm

US ASD-1 and AN/APS-3 on Coastal Command Catalinas

 

 

 

IX

3cm

ASH or AN/APS-4 pod mounted light version of Mk.VIII

 

 

 

X

3cm

US H2X or AN/APS-15. Mk.V/VIII combination from Dec 1944 in Swordfish III, Barracuda TR.III and Liberator VIII

 

 

 

XI

3cm

ASV X range only radar. Used in under fuselage radome in Swordfish III from mid-1944

 

 

 

XII

10cm

ASV version of AI Mk.VIII with search facility and range finding introduced 1945 for strike aircraft, mainly Beaufighter TF.X

 

 

 

XIII

3cm

Mk.XI development for Shackleton MR.1&2 postwar

XIIIA

3cm

Improved Mk.XIII

XIIIB

3cm

XIIIA with roll stabiliser

XIIIC

3cm

Improved XIIIB

 

 

 

XIV

3cm

Re-designed XIII

 

 

 

XV

3cm

Lightweight ASV

 

 

 

XVI

10cm

Small ranging device for strike aircraft such as Beaufighters introduced early 1945

 

 

 

XVII

10cm

Final wartime production ASV adapted for Warwicks

 

 

Early Coastal Command Liberator GR.III/V often carried both ASV.II and ASV.IV/V, although only the nose Yagi would be fitted. This seems to have been used for homing purposes but I’m not entirely clear how this worked. Most of the differences between a Liberator GR.VI and a GR.VIII were internal relating to the electronic fit, except for those that related to the exact model of B-24 on which they were based.

 

Turning to your question about USN PB4Y-1 aircraft there is a difference between those operated in the Pacific and those in the Atlantic. The Atlantic based squadrons (VPB-103,105,107,110,112,113 and 114), were anti-submarine squadrons and therefore generally carried radar once sufficient sets became available. Those sets would start as Yagi arrays before moving to the “Dumbo nose” and then the belly mount in place of the turret. In the Pacific their role was more one of search and strike against surface ships not submarines. Also the weather tended to be better making the Mk.I eyeball the better means of detection. They could also expect to meet enemy fighters. So they retained their belly turrets and went without radar in most cases. As in all these things you will find exceptions, for example I have a photo of VMD-154 & 254 PB4Y-1s on Guadalcanal in late 1942 early 1943 with underwing Yagi aerials indicative of ASE radar

 

Later the USN developed the PB4Y-2 Privateer (identifiable by its longer fuselage and single tail) for the Pacific war which began to enter service in late summer 1944. It carried a whole host of “lumps and bumps” for radar (which retracted into the lower forward fuselage) and various ECM detectors and jammers.

 

As John Aero has pointed out there were also radio devices used for navigational and homing purposes that had their own aerials. Without seeing a specific example then it is almost impossible to say what a particular aerial is for.

 

Apologies but the formatting of the table I set up for the various Britich ASV sets had gone to pot. I hope that you can still make sense of this data.

[Graham Boak]

SBDs and TBF/M carried small Yagi arrays underwing, angled outward, rather like the larger arrays carried by Swordfish between the wings, and Catalinas outboard of the wing struts.  This US equipment wase known as Baker equipment (possibly that is not the full code name but memory only goes so far)

 

Remember that photographs showing these may well have been censored so that aircraft will appear to have no radar when in truth they did.

Edited December 7, 2019 by Graham Boak

[dogsbody]

The H2S scanner on the Lancaster was left unpainted on the rear section because it covered the navigation/identity lights on the lower rear fuselage.

 

 

 

Gee, G-H,Rebecca, etc, were not radar, but were radio navigation aids.

 

 

 

Chris

[John Aero]

Chris,  Beg to differ, In the RAF, Gee, G-H, and Rebecca and IFF.10 were Radar sets working on Radar Frequencies, The were only serviced on aircraft by Air Radar Mechanics and Fitters and also in the Radar servicing bay. Details of these equipment's were found in the Radar section of the relevant aircraft AP.   Air Wireless personnel looked after the Air Wireless/Radio VHF and UHF transmitters and receivers and Radio Direction Finding and homing equipment such as Radio Compass on aircraft and in the Air Wireless Bays.  Air Radar and Air Wireless only became dual trade in the 70's on the 'Gipsy' squadrons such as the Harrier Force.

 

John

[dogsbody]

Okay, Rebecca and IFF were radar based, but not these two.

 

 

https://en.wikipedia.org/wiki/Gee_(navigation)

 

https://en.wikipedia.org/wiki/Gee-H_(navigation)

 

 

 

Chris

[John Aero]

Wiki are not always right by any means. These sets both used Oscilloscope screens with a pulse timebase. which in the wisdom of the RAF made them Radar gears.   I did the Gee H and Rebecca 4 course Navigation Bomber 26, in 1960 at RAF Yatesbury as an Air Radar Technician. The pure Navigation Gee 2 Radar fitted to our Anson (TX!76 in which I flew a good few hours) also came under our wing. Later Radar courses I did were Gee 3, Green Satin (Doppler Nav) and IFF.10. again both Radar equipment. Followed later by Terrain Following Radar, Tacan and Laser.

 

John

 

[EwenS]

Expositor

Further to my last post, it needs to be remembered that Britain needed to productionise its technology at a much earlier stage than the US due to the fact that it was actually in a war. ASV.II was productionised in Britain in early 1941.  It was then given to the US (with the forward looking Yagi transmit and separate receive aerials), renamed the SCR-521 containing locally produced components, after which development continued in parallel in both countries. As a result the aerial systems for the sideways "Search" differed.

 

I've just finished reading Rob Stitt's book on the Fortress in Coastal Command. With one or two exceptions, these aircraft were delivered in 1942. The first few to be delivered had no radar fitted, and some were given British built sets on arrival. Then came aircraft with 3 Yagi homing and US search aerials (see the US reference I gave you) and then the final deliveries were delivered with 3 Yagi homing aerials only (because Britain found the US search arrangement didn't work so had it removed from the delivery spec). Then in 1943 they were brought up to a common standard with British "Search" aerials on the fuselage sides (no transmit array on the fuselage spine in most cases implying the fitting of transmit/receive modules) and 3 Yagis on the nose.

 

The earliest RAF Liberator GR.I/II were fitted out for the task here in the UK (25 aircraft in total). As for the GR.III delivered from the US from March to Sept 1942 (and there were only about 57 of them plus 11 IIIA) I'm not clear if the radars were fitted in the US or the UK. By the time that these aircraft reached squadron service they only had fuselage side aerials and 3 forward looking Yagis.

 

EDIT: Correction. I’m not following my own logic re this last para. The fuselage side aerials are the British style 2 rows of 4 and not the US style wire as per B-17. So the side looking Search set must have been installed in Britain as one of the Coastal Command mods. The 3 forward looking Yagis could have been fitted in the US before delivery. Back to the original post.

 

 

As I've noted even some centimetric radar equipped Liberator GR.V aircraft retained a Yagi associated with ASV.II on the nose, AIUI for use on homing to their bases.

 

To pick up on your point about the radar aerials on the SBD and TBF/TBM, they were fitted with the US ASB radar. This radar entered production in late 1942 and therefore would benefit from the transmit / receive modules that I referred to being fitted from the outset. Hence the presence of only a Yagi aerial under each wing and no third transmitting aerial.

 

Other production start dates for US / Canadian radar sets (all centimetric sets) I've found are

DMS-1000 from 3/42 (as fitted to the earliest Liberator GR.V deliveries from 8/42)

ASG from 10/42

ASD from 6/43

ASH or AN/APS-4 from 10/43

 

I've also realised that you also need to bear in mind that, in the US, anti-submarine land planes were the domain of the USAAF in the early war period. It was only in July 1942 that the two services did a deal to hand AS work to the USN in exchange for the USN giving up an aircraft plant to B-29 production. But it took until August 1943 for the USAAF Anti-Submarine Command to be disbanded and an extra couple of months before the last units changed role or disbanded. So photos of the very earliest radar equipped land based aircraft (those most likely fitted with 3 Yagi aerials) are likely to be found in USAAF archives and not those of the USN. So we are talking about B-17 (as illustrated on the US link I provided), B-18, B-24, B-25 and B-34. The USN only started to take delivery of its own B-24D/PB4Y-1 aircraft in Aug 1942 and then had to fit them out to its own standards. That time line generally seems to fit with transmit/receive modules becoming available and so only underwing aerials would be required for the 1.5m sets of whatever designation. 77 surviving USAAF anti-submarine B-24s went to the USN from July 1943 but any surviving USAAF B-17/B-18/B-25/B-34s seem to have gone to training units in the US. It is amongst those aircraft that I would expect to see evidence of the earlier radar aerial configurations.

 

As has been pointed out by someone else, with radar being a closely guarded secret, particularly in the early war years, photos of aircraft so equipped were actively discouraged or were censored before release. It is not always obvious when this has been done, but it usually saw the removal of all aerials not just some.

Edited December 9, 2019 by EwenS

[expositor]

Thanks to all who contributed.  Ewen, I appreciate your time in clearing things up for me.  The first link you provided was the site I mentioned, which showed the RAF style dorsal array which only some USAAF B-24s in Alaska used, as far as I could find.  The USN patrol bombers didn't use that set- up to any extent if at all, just the single row of transmit aerials along the rear fuselage under the waist guns, and the under wing yagi receivers, as you indicated, for general search. The army B-24s transferred to the USN appear to have had the ventral scanners as the new production anti-sub PB4Ys had. The few B-24s which had the under nose scanner remained with the army in No.Africa, so I believe.  

The only US Atlantic anti-sub plane with a nose yagi I could find a photo of was an army B-18 from 1942.

I'm still confused seeing photos of a few PB4Ys with the rear transmitter array, belly turret, and no yagis under wing, in the Pacific.  You confirmed my assumption that the single engine USN planes had transmit/ receive yagi antennas, but those bombers with side fuselage aerials doing both?  A return signal would be harder to home in on with only those, no? 

Thanks again for all the enlightening posts!

 

Jim

 

[EwenS]

Jim

I’m also confused about these early radar arrays, especially that of the side looking SCR-521/ASE set and have had a few more thoughs.

 

The RAF decided very quickly that the side looking US set didn’t work. The first B-17E/Fortress Mk.IIA so equipped arrived in Britain in late June 1942 and by August Coastal Command were stating it was “useless”. The B-17F/Fortress II being converted from August 1942 at Cheyenne didn’t get it. No RAF Liberator ever seems to have received it. By August 1942 the RAE at Farnborough were aware that the US had transmit/receive modules in production but that the UK was lagging in the production of these, to their embarrassment.

 

The USAAF only had 2 squadrons operating B-24s in Alaska during the war, so numbers are few. Most of the photos I’ve seen of B-24s that are clearly identifiable as having the full side looking US aerial array are wrecks such as B-24D-7-CO “Gremlins Delight” which was written off in Feb 1943. This was a very early aircraft off the production line. Radar of any kind would be useful in this theatre due to the bad weather making finding a way home difficult.

 

The USN started accepting B-24Ds in Aug/Sept 1942 as PB4Y-1s but the first 10 were not refitted with USN equipment. The first to receive such equipment were from the B-24D-13-CO and D-15 blocks. This is after the date that the RAF were aware that the US already had transmit/receive modules so it is possible that the USN were able to benefit from this, allowing the transmit aerials on the fuselage top to be eliminated and using the fuselage side receive aerials both as transmitter and receivers. But this raises a question as to why the USN would still be fitting a “useless” set in its aircraft from Sept/Oct 1942 when better centimetric sets were already in production. The RAF accepted its last Liberator Mk.III at Dorval on 2 Oct 1942 and after that deliveries were of centimetric equipped Mk.V.

 

There are other possibilities of course.

1.       The angle photos are taken from may mean that the high mounted B24 wing obscures the top of the rear fuselage where our “missing” aerials would be.

2.       A censor has removed the upper aerials (standing out against a skyline?) but left the side aerials which tend to be very hard to see anyway.

3.       The side aerial arrays we are seeing were being used for something else. I’ve seen one photo that looks like it should be the side array but on closer examination there are only shadows from 3 separate aerials without any joining wire (Thunder Mug of VB-109)

 

The squadrons that seem to reveal these side aerials most often are those from VMD-154 & 254 which were amongst the first to receive PB4Y-1s along with VPB-101.

[expositor]

Ewen, that Thunder Mug picture is the first one where I noticed the side array without the under wing antennas.  Photos of the USMC planes I've seen all had the yagis like the early USN Pacfic theater PB4Ys.  Now I notice quite a few planes with those side antennas without any under the wings.  I thought about censors, but the only antennas they really seemed to be concerned about were those various nose aerials, sometimes with a jacket over them so the censor didn't have to scratch them out of the photo. Still, a side array without the wing antennas?  Puzzling....

Thanks again for sharing your knowledge!

 

Jim

[OCDSpecial]

I see Pictures of Consolidated Catalinas in RAF Coastal Command mid 1944 that appear to have radars mounted in randomes over the cockpit - what are these?

Trying to build RAF / Commonwealth VC aircraft and am trying to determine what radars Horrnell - PBY 5A 9754 - show the Yagi type along the sides and outboard of the engines, while  Cruickshank - Cat IVA JV928 "Y" shows the above described randome type?

I am trying to source 1/72 scale of these as aftermarket, no luck so far!

Source https://weaponsandwarfare.com/raf-vc-aircraft-and-crews-pilots/

 

[Planebuilder62]

Dear OCD

Quickboost sell these radomes in 1/72 scale.

regards Toby

[EwenS]

42 minutes ago, OCDSpecial said:

I see Pictures of Consolidated Catalinas in RAF Coastal Command mid 1944 that appear to have radars mounted in randomes over the cockpit - what are these?

Trying to build RAF / Commonwealth VC aircraft and am trying to determine what radars Horrnell - PBY 5A 9754 - show the Yagi type along the sides and outboard of the engines, while  Cruickshank - Cat IVA JV928 "Y" shows the above described randome type?

I am trying to source 1/72 scale of these as aftermarket, no luck so far!

Source https://weaponsandwarfare.com/raf-vc-aircraft-and-crews-pilots/

 

 

The Catalina radars in the pod above the cockpit were ASV Mk.VIII or VIIIA (US designations ASD or ASD-1 respectively). See the list in my post #4 above.

 

The aerials for the PBY-5A 9754 would be for ASV.II with thecsearch aerials on the fuselage and homing aerials under the wings as previously described.