The AN/APS-13 Tail Warning Radar Conundrum

[yahya]

In this thread I would like to focus on situations when an avionics piece backfired and instead of providing security, it contributed to serious risks. This is a story of the RAF Monica (ARI 5664) tail warning radar and its US clone known under the nomenclature of AN/APS-13. Monica appeared in the second half of 1942 in British bombers. It was in fact a ranging radar operating at about 320 MHz, which gave the crew a visible and audible warning about a hostile airplane approaching from the rear within several hundred meters. Unfortunately, the Luftwaffe learned about Monica's existence from a bomber that accidentally landed in continental Europe. In consequence, German scientists developed in early 1944 the FuG 227 Flensburg receiver, which allowed the night fighters to home in on the Monica signals from up to 100 km. This merely streamlined the interception of allied bombers at night. The British learned about the FuG 227, when a Ju-88 night fighter mistakenly landed on British soil in June 1944 (See this). Thus, the Monica was phased out.

US AN/APS-13 was used in the P-51s and P-47s, but when the risks involved with their use became apparent, the sets eventually saw use as the proximity fuze system of nuclear bombs dropped on Japan in August 1945.

The AN/APS-13:

American airborne radar detector, type RT34/APS-13 | Science Museum Group Collection

American airborne radar detector type RT34/ASP-13, 1939-45.,The equipment used a directional aerial in the rear fin for both transmission and reception, the main lobe of transmission being such that there was half field strength at plus or minus 45 degrees vertically and 30 degrees horizontally...

collection.sciencemuseumgroup.org.uk

AN/APS-13 (SCR 718) airborne tail warning radar

AN/APS-13 (SCR 718) airborne tail warning radar

www.radiomilitari.com

AN/APS-13 in P-51D's cockpit:

Kiwi Aircraft Images : 01mstg12 : Photo Page

Similar situation occurred with the H2S radars carried by RAF bombers. Their signals could be detected by the FuG 350 Naxos Z and allowed German night fighters to home in on these radars.

 

[HoHun]

Hi Yahya,

In this thread I would like to focus on situations when an avionics piece backfired and instead of providing security, it contributed to serious risks.

It seems that the radar-ranging gunsight of the F-86 used in the Korean war pretty quickly resulted in the development of a warning receiver by the Soviets. Can't find the source right now, though.

Regards,

Henning (HoHun)

 

[yahya]

If memory serves, the first Soviet RWR that detected the F-86 ranging radar was home-made during the Korean war by a Soviet pilot and dedicated engineer. I can't recall his name now. Only then the design on the future SPO-2 Sirena RWR commenced.

 

[yahya]

See this for more information on Soviet RWRs:

https://www.secretprojects.co.uk/threads/soviet-russian-rwr-sirena-beryoza-pastel.48/post-20864

 

[yahya]

Hi Yahya,



It seems that the radar-ranging gunsight of the F-86 used in the Korean war pretty quickly resulted in the development of a warning receiver by the Soviets. Can't find the source right now, though.

Regards,

Henning (HoHun)

Hi Henning,
I've just found the article on the MiG-15 tail warning receiver that warned about the AN/APG-30 emanations from the F-86s:

To Snatch a Sabre

Fifty years ago, North Korea's secret allies plotted to heist from the United States a North American F-86.

www.smithsonianmag.com

 

[Trident]

Kremniy IFF vs. Combat Tree NCTR?

https://www.secretprojects.co.uk/threads/soviet-russian-iff.792/

 

[Justo Miranda]

Hi Henning,
I've just found the article on the MiG-15 tail warning receiver that warned about the AN/APG-30 emanations from the F-86s:

To Snatch a Sabre

Fifty years ago, North Korea's secret allies plotted to heist from the United States a North American F-86.

www.smithsonianmag.com

Despite its failure in Korea, the MiG-15 became very popular in the Western world when was presented by the myth-making Soviet propaganda services as the most advanced fighter in the world, and again the lack of information gave rise to all kinds of legends. Here below are some examples of rumors not confirmed by documentary evidence:

When the Soviets became aware of the technological superiority of the Sabre the Premier Joseph Stalin gave the order to “snatch” an F-86.

Soviet intelligence agents monitored USAF radio frequencies, interrogated prisoner pilots, and mobilized their spies in the USA to obtain technical information about the American fighter. According to an article published by Weekly Standard on March 28, 2011, the NACA employee William Pearl microfilmed 1,885 pages of F-86 tailplane and slats documents for the spy Martin Sobel.

In April 1951 a special group of test pilots, headed by Lieutenant Colonel Dzyubenko, practiced precision formation flying in MiG-15 with the mission of boxing an F-86 and forcing it to land in North Korea.

Although the “snatch” mission was a failure, the capture of the F-86 A (49-1319) landed in North Korean coast practically unscathed on October 6, 1951, and one F-86E on July 1952, gave the Soviets access to the American secrets of automatic slots, fully movable tailplane, Sperry APG-30 radar gunsight (which in 1957 was installed on the MiG-17F as SRD-1M Scan Fix rangefinder), G-suits and crash helmets.

On December 1951 the TsAGI engineer VV Kondratiev, who was testing the captured F-86 A, managed to get Stalin interested in the idea of reverse engineer the Sabre.

In December 1952 the Moscow Plant No.1 was reoriented to the mass production of IL-28 jet bombers and F-86 airframes, it was decided that the production of wings and tails will be transferred to the Saratov Plant Nº 292 and the pressurized cockpit and final assembly to the Kuibyshev plant, but the project was cancelled by January 1953.

 

[yahya]

Kremniy IFF vs. Combat Tree NCTR?

https://www.secretprojects.co.uk/threads/soviet-russian-iff.792/

You're absolutely right. Soviet-made SRO-2 IFFs were exploited with the AN/APX-80 Combat Tree. The only solution for Vietnamese pilots was to turn their IFFs off.

More on the subject for those interested:

AN/APX-80 Combat Tree : United States of America (USA)

www.armedconflicts.com

How Combat Tree Made the F-4 Phantom II the Deadliest Fighter Over Vietnam in the 1970s

Imagine, as a fighter pilot, being able to see your enemy without them knowing you’re even in the area. Sounds like some newfangled stealth capability you’d expect to come stock on a fi…

tacairnet.com

This is what made the F-4 Phantom II the deadliest fighter to fly over Vietnam

Imagine, as a fighter pilot, being able to see your enemy without them knowing you're even in the area. Sounds like some newfangled stealth capability you'd expect to come stock on a fifth generation fighter, like the F-22 Raptor or the F-35 Light…

www.wearethemighty.com

"Combat Tree" Enemy IFF Interrogator - SimHQ Homepage

SimHQ provides the latest news, previews, reviews, feature articles and resources for PC computer and console simulation gaming. Share tips and techniques in the SimHQ forums about new simulation releases, as well as the classic simulations. SimHQ covers combat flight simulations, land and armor...

simhq.net

 

[RHVERNON]

Full history of the development of Monica and all of the avionics systems used by the RAF is covered on the Air Historical Branch section of the RAF web site under the Themed Studies Section.

THE SECOND WORLD WAR 1939-1945
ROYAL AIR FORCE SIGNALS

There are 9 downloadable PDF which cover the use of Telecommunication, Radio, Radar and other signals systems used by the RAF in WWII both on the ground and in aircraft. It is a gold mine of information about how the equipment came about, the issues in its development and what worked and what didn't.

Monica is covered in in Vol III chapter 1-11. link below to page with all the links.

https://www.raf.mod.uk/our-organisation/units/air-historical-branch/second-world-war-thematic-studies1/

 

[Basil]

Full history of the development of Monica and all of the avionics systems used by the RAF is covered on the Air Historical Branch section of the RAF web site under the Themed Studies Section.

THE SECOND WORLD WAR 1939-1945
ROYAL AIR FORCE SIGNALS

There are 9 downloadable PDF which cover the use of Telecommunication, Radio, Radar and other signals systems used by the RAF in WWII both on the ground and in aircraft. It is a gold mine of information about how the equipment came about, the issues in its development and what worked and what didn't.

Monica is covered in in Vol III chapter 1-11. link below to page with all the links.

https://www.raf.mod.uk/our-organisation/units/air-historical-branch/second-world-war-thematic-studies1/

Interesting - from page 151 ff the development path which led to Village Inn is described.

 

[sienar]

Why was it named Monica? I've heard that it was something risque but what exactly.

 

[TMA1]

I dont think the mig-15 was at all a failure. Also I think Soviets had already brought fighters into production that had automatic slats and they had already been studying horizontal stabilators in the transonic regime before ever studying a saber jet.

...also I do not think the Soviets would have seriously considered reverse engineering the saber. It was superior in most ways to the mig-15 but by the time of the Korean conflict newer vastly superior fighters were being developed compared to the f-86 and the Soviets were aware that we were quickly advancing as well.

edit: I also get a bit miffed when I see the "ruskie propaganda made it out to be a super wonder weapon but we soon found out it was junk" trope.

 

[HoHun]

Hi,

I dont think the mig-15 was at all a failure.

Here's a quite balanced evaluation of the MiG-15 vs. the F-86E in Korea, based on the combat experience of the USAF:

https://www.secretprojects.co.uk/threads/australian-archives-combat-evaluation-of-meteor-viii-mig-15-f86a-f86e-in-korea.42098/#post-619342

The F-86E according to this evaluation only holds an advantage more significant than "slight" in steep dives at >= 0.95 Mach, and even that's classified as just a "limited" advantage.

The MiG-15 on the other hand holds "moderate" to "definite" advantages in everything that's thrust-to-weight-ratio dominated (climb, zoom, ceiling, acceleration.), at least at high altitude, and enjoys a slight to limited advantage in top speed above 30000 ft too.

Additionally, in the same thread there's also a USAF discussion of the armament of both types, and the MiG-15's guns are pretty clearly considered superior.

So at the time, the USAF didn't consider the MiG-15 a failure at all, but a fighter equal in many respects (and superior in some) to their own F-86E, which at the time probably was their latest and best air superiority fighter.

If anyone considered the MiG-15 a failure, I suppose that would be based on the kill ratios the F-86 supposedly achieved over Korea, which I believe are today recognized as exaggerated (even though they might have been based on the best available intelligence at the time).

Regards,

Henning (HoHun)

 

[BlackBat242]

Yes... .50 mgs, even with 6 not requiring aiming to a convergence, simply were inadequate for aircraft flying at nearly the speed of sound.

The F-86H, most of which had 4x 20mm cannon, had the better armament for both air-air and air-ground - but they were too late for Korea and had a higher wing-loading which reduced maneuverability (especially at altitude)... which was unfortunate as their more powerful J73 engine and larger fuselage meant it had a shorter take-off run, accelerated faster, climbed faster, had a higher ceiling, had a higher cruising speed, and was longer-ranged (internal fuel increased from 435 gallons to 562 gal.).

North American F-86H Sabre

 

[HoHun]

Hi,

The F-86H, most of which had 4x 20mm cannon, had the better armament for both air-air and air-ground - but they were too late for Korea

I guess this shows at least that USAF procurement respected USAF combat experience! Not always a given ... ;-)

Regards,

Henning (HoHun)

 

[T. A. Gardner]

You're absolutely right. Soviet-made SRO-2 IFFs were exploited with the AN/APX-80 Combat Tree. The only solution for Vietnamese pilots was to turn their IFFs off.

More on the subject for those interested:

AN/APX-80 Combat Tree : United States of America (USA)

www.armedconflicts.com

How Combat Tree Made the F-4 Phantom II the Deadliest Fighter Over Vietnam in the 1970s

Imagine, as a fighter pilot, being able to see your enemy without them knowing you’re even in the area. Sounds like some newfangled stealth capability you’d expect to come stock on a fi…

tacairnet.com

This is what made the F-4 Phantom II the deadliest fighter to fly over Vietnam

Imagine, as a fighter pilot, being able to see your enemy without them knowing you're even in the area. Sounds like some newfangled stealth capability you'd expect to come stock on a fifth generation fighter, like the F-22 Raptor or the F-35 Light…

www.wearethemighty.com

"Combat Tree" Enemy IFF Interrogator - SimHQ Homepage

SimHQ provides the latest news, previews, reviews, feature articles and resources for PC computer and console simulation gaming. Share tips and techniques in the SimHQ forums about new simulation releases, as well as the classic simulations. SimHQ covers combat flight simulations, land and armor...

simhq.net

Not entirely a new idea. The RAF did the same thing in WW 2 with their Perfectos ESM system. It would trigger German FuG 25a Erstling IFF sets and provide a bearing and rough range on the target. The British also had Serrate that was the reverse of Flensburg. Serrate gave a pretty exact bearing and rough range on most German airborne radar sets.