[ARC5] ASV radar for a PBY

Thu Mar 10 17:31:42 EST 2022

Hello Ray,

I wish this PBY had an ASB set as we can still find those components and life would be much easier. 

I would just like to start off with a manual or photos showing the ASV components so I can start looking and spreading the word. 

Going by the available photos I have come across, there seems to have been quite a few early PBY installations using the Sterba array. 

Attached are photos of a wartime Sterba on a PBY and a shot taken yesterday of the antenna mooring fittings still on the top of the aft fuselage after 80 years. Fun detective work indeed.

Thanks,

Taigh

Taigh Ramey

Vintage Aircraft Inc.

7432 C.E.Dixon Street

Stockton, California 95206

(209) 982-0273

(209) 982-4832 Fax

 <http://www.twinbeech.com/> www.twinbeech.com

KEEP 'EM FLYING...FOR HISTORY!

From: raydio862 at verizon.net <raydio862 at verizon.net> 
Sent: Thursday, March 10, 2022 6:44 AM
To: 'Bart Lee' <kv6lee at gmail.com>; 'Taigh Ramey' <taigh at twinbeech.com>
Cc: Vintage-Military-RADAR at yahoogroups.com; 'ARC5' <Arc5 at mailman.qth.net>; 'milsurplus at mailman' <milsurplus at mailman.qth.net>
Subject: RE: [ARC5] ASV radar for a PBY

Bart & Taigh,

That’s fantastic information, I was not aware of the use of the Sterba array antenna to improve search capability.  But the account clearly describes the ASB radar system with two yagi antennae.  The vertical “A” display is actually called a “B” scan with pips to the right and left from the two yagi antennae.  Equalizing the pips points the aircraft to the target.  As I indicated previously, the ASB operated at 515 Mhz with conventional vacuum tubes.  The article is a testimony to the cooperation between the Brits and Americans to exploit the benefits of ASV type radar.  I am not familiar with the British Mk ASV radars but I believe that the ASB equipment was a big improvement on the original British ASV system hardware.  I do not think that the Sterba array was used too much as I never ran across it before.  I’m sure the pilots loved it as it must have really altered the PBY flight characteristics.

I have a complete ASB-4 system without antennae but with a few duplicate units including a duplicate indicator scope.  I also have some tech manuals and some details on the yagi antenna that I obtained from the National Electronics Museum (NEM).  I am a radar historian and curator of the Radio Technology Museum (RTM) at the campus of the InfoAge Science and History Center in Wall, New Jersey.  In my years of searching, I have not been able to find one of the original yagi antenna.  Over 20,000 ASB systems were produced during WWII with variations as technology improved.  I think the major intended use was for single engine carrier borne aircraft.  As far as I know, it was the first use of aircraft search and fire control radar by the United States.

I will supply as much help as I can for your project.

Ray

From: arc5-bounces at mailman.qth.net <mailto:arc5-bounces at mailman.qth.net>  <arc5-bounces at mailman.qth.net <mailto:arc5-bounces at mailman.qth.net> > On Behalf Of Bart Lee
Sent: Thursday, March 10, 2022 1:23 AM
To: Taigh Ramey <taigh at twinbeech.com <mailto:taigh at twinbeech.com> >
Cc: Vintage-Military-RADAR at yahoogroups.com <mailto:Vintage-Military-RADAR at yahoogroups.com> ; ARC5 <Arc5 at mailman.qth.net <mailto:Arc5 at mailman.qth.net> >; milsurplus at mailman <milsurplus at mailman.qth.net <mailto:milsurplus at mailman.qth.net> >
Subject: Re: [ARC5] ASV radar for a PBY

Taigh, FWIW, here's some background on the British development of Air to Surface Vessel (ASV) Radar and the use of the Sterba antenna:

PBY ASV RADAR (Air >> Surface Vessel)

Sterba Antenna on the PBY (and/or Catalina)

==. ==

 <http://www.warbirdinformationexchange.org/phpBB3/viewtopic.php?p=524687> http://www.warbirdinformationexchange.org/phpBB3/viewtopic.php?p=524687

If my memory serves me correctly,  the search antenna was a Sterba Array which stretched between the aft section of the wing and the tail emphanage and provided a figure "8"  transmit/receive pattern for search,  and when a target was acquired,  the radioman informed the pilot of the direction (i.e. port or starboard) of the target acquisition ... the pilot reported back to the radioman, "OK, making a turn to Starboard... or Port, ... as required"..... at that time the radioman would shut down the ASB (we used to refer to it as the Baker gear) modulator,  manually disconnect the two Sterba Curtain Array coaxial cables from the motor driven mechanical switch,  attach the the two coaxial cables driving the Port and Starboard Yagi antennas having a relatively forward uni directional mode ... again power up the ASB modulator ... and then with his vertical "A"  RADAR display  direct the pilot either "right or left" as required to display equal amplitudes of the vertical "A" display " pips ... indicating a "homing in" mode.    Long time ago,  but as I recall,  the maximum range was 80 KM... but I stand corrected if anyone wants to dispute that figure. [Don't ever remember acquiring any targets at that range ... however!!!]  Jeez!   What an improvement  ARPA Radar and Raster Scan of Sperry Radar for Merchant Marine...Collision Avoidance System RADAR  (CAS) has been since that time!!! 

Walt B. #5507

==. ==

[British development]

Shortly after moving to St. Athan in 1939, Hanbury Brown received a request to fit ASV to the  <https://military-history.fandom.com/wiki/Armstrong_Whitworth_Whitley> Armstrong Whitworth Whitley bomber, which was no longer competitive and was being passed off to other uses. Brown took the chance to develop a new antenna, a type of Sterba array, that stretched along both sides of the flat rear fuselage, firing to the side instead of forward. This "broadside array" allowed the aircraft to search wide areas of the ocean on both sides of the aircraft at the same time, a great improvement over the forward-only design.

The broadside array offered about 2.5 times the gain of the original system. This allowed it to detect moderate-sized ships at 40 miles (64 km) and surfaced submarines at 10 to 15 miles (16–24 km), an enormous advance over the Mk. I style antennas. The aircraft could scan the approaches to a convoy by flying 10 miles to one side of it, sweeping a 20-mile wide path. Submarines were not fast enough to cross that distance before the aircraft had returned for another sweep. There was some discussion of giving it a special display to make interpretation easier, but it went into service using the original ASV display instead.

 <https://military-history.fandom.com/wiki/ASV_Mark_II_radar> https://military-history.fandom.com/wiki/ASV_Mark_II_radar

==. ==

73 de K6VK 09 III 22 ##

-- -- 

Bart Lee, K6VK, CHRS Archivist and Fellow, AWA Fellow, ARRL Liaison

Texts only to: 415 902 7168 

 <http://www.bartlee.com/> www.bartlee.com 

{KV6LEE(at)gmail(dot)com} ##

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