Thanks for the great vid and correction. I always thought that was very practical the Manhattan project engineers used this off the shelf item for the final trigger.
Thanks for the correction, saved me a post. AFAIK even 1800 was found to be too high - a lot of the atomic tests in the 1950s were "height vs yield" tests to determine the optimal height for bursts of various explosive yields. 1,800 feet was thought to have been too high for a European or North American style city but they used the higher altitude as they assumed that Japanese cities, being more flammable, would suffer more from a higher and thus more extensive blast radius.
The bomb was ground detonated by the Jesuit priests who survived (attributed, naturally, to a "miracle of Mary") at [close to] ground zero, underground. Both previous tests were ground based. They've carried on this lie for 80 years to scare the populace into compliance with defense budget spending. There is no such thing as airborne nuclear war. Sorry to burst the bubble.
I assumed that was what you meant as 18,000 feet burst height makes no sense for weapons of that yield. 18K feet was close to the burst height of the 50 MT Tsar Bomba (found it to be 4 km after a quick google search). For the limited yield of those early weapons 1,800 ft makes more sense.
"Monica" it was called. But, alas, german nightfighters soon learned of the device and developed a homing device, based on the beam this radar was creating!😮
MSD ..............I considered myself as a knowledgeable 71 year old of things WW 2 and with you on this ..........even knew a P 47 pilot who made thru the war .
I knew they were used on the tail turret of RAF Lancaster bombers to warn of approaching Luftwaffe night fighters. I guess the Lancaster was big enough to house the equipment and had multiple crew to operate the system (for example the Navigator’s station had a CRT display for the H2S radar) . But I never knew they were used on smaller, single seat, allied fighter aircraft.
@@notmenotme614 I also never new about this US system. But I have seen a couple of old RAF films about the "Village Inn" aka AGLT (automatic gun laying turret) system for British heavy bombers.
Yes. Same here. What's really great about the system, based on my experience sailing using radar and AIS (identification radio signals). The false positive alerts: flak, drop tanks, friendlies, builds confidence in the system. The same is true with radar on a boat picking up a fishing buoy (Attraction device - more than just bobbing thing the size of a basketball). And the last listed advantage cannot be overstated. Enemies fighters do more than just shoot you down, that they exist and there's even the slight possibility get in behind you is a significant cognitive load and stressor that reduces how much concentration can be put on other aspects of the mission. Huge plus. The way a proximity warning system works on a boat is you can go to sleep knowing the system will wake you before any nearby vessel can be close enough to be a problem. If you don't have this even mid ocean where you might not see another vessel for weeks, you can't safely sleep more than about 45 minutes.
Tail warning radar on RAF night bombers was compromised and I believe deleted when it was found that Luftwaffe night fighters were using its emissions to find and home in on the same bombers. Perhaps more useful on fighters operating during the day?
@@markstott6689 The monica tail warning radar (that the AN/APS-13 was copied from) was being withdrawn and was almost replaced with the more effective fishpond microwave system (an add on to H2S microwave radar navigation) by the time the RAF discovered the Flensburg system. Fishpond had been developed and deployed rapidly in a response to an uptick in losses to nightfighters.
Interesting point. I've learned from these videos that the Germans didn't think microwave radar was even possible... Not sure how true this was, or what frequencies are involved in these two systems. Also this video does an excellent job presenting the logical reasoning used to create, deploy and understand this system. I wonder how effective was the reasoning of other WWII combatants developing their systems.
@@johnculver2519from what I’ve read fishpond when used correctly and when working correctly was very good 👍it allowed the bomber to suddenly corkscrew out of danger but wasn’t good at low altitudes as its coverage area was too small
@@tedarcher9120 Magnatron technology was invented in the US by Albert Hall working at General Electric Research Laboratory, circa 1912, it was further developed in the US by A.L. Samuel of Bell Laboratories in 1934. The CAVITY magnatron, a variation of magnatron technology, was introduced by John Randall and Harry Boot of the University of Birmingham in 1940.
@@tedarcher9120 No, the magnetron brought over to the US by Tizard made microwave *generation* practical, but it was the work of I I Rabi's Rad Lab that made radar *receivers* effective. The Rad Lab made a much bigger contribution to winning the war than the Manhattan Project. The US had klystrons, but they were too heavy, complex and low power to make effective fighter based radar.
@@dukecraig2402 What Hall invented was nothing to do with radar at all, it was simply a valve that used a magnetic field to modulate the anode current. The cavity magnetron was invented in Germany in 1935 but the Germans failed to exploit it due, basically, to a lack of imagination. Randall and Boot solved the technical problems and a 20kW magnetron was sent to the USA with the Tizard mission. This rapidly led to improvements in radar. The Germans never got past klystrons, which the USA was using until Tizard, which were limited to tens or hundreds of watts. On your logic Thompson invented the magnetron in the 19th century because he used magnetic fields to bend the electron beam in his cathode ray tube.
@EbenBransome It's not "my logic" and I never said anything about who invented radar, did I? I was simply pointing out steps of magnatron development for the sake of those who think that the cavity magnatron was the start of everything magnatron, it wasn't, and the cavity magnatron wasn't the start of radar either nor is it exclusive to radar, radar already existed before the cavity magnatron, what the cavity magnatron did was make much smaller radar sets possible.
Considering the amount of German aces who specialized in getting in sniffing distance to the rear before pumping out the 20mm, it makes a lot of sense this would have an impact.
These systems were probably more useful in the Pacific where a fighter pilot who got separated from everyone else didn't have reference points on the ground like pilots in Europe did and had to concentrate on fixing his location so he could find his way back to a tiny dot in the ocean or ditch from running out of fuel, it gave them the peace of mind to concentrate on the math of navigation without constantly having to worry about someone sneaking up behind him.
@@sliceofbread2611 Sorry, when I mentioned a "tiny dot in the ocean" I should have included the word "island" as I did in another post here, I was talking about the land based Army fighter's, whether or not the Navy and Marine land based fighters in the Pacific ever had this system (or even their carrier based fighters for the sake of rear attacks) I don't know, I've never heard an account of them having them but that doesn't mean they didn't.
These systems were particularly useful on fighters in the Pacific where they were flying over water and didn't have navigation reference points on the ground like the fighters in Europe did, flying over water in the Pacific meant that they had to occupy themselves with their little navigation computers (not electronic computers, the little circular "pinwheel" calculator navigation devices) to figure their position, one little mistake and a fighter pilot who was on his own after getting separated from the rest could easily miss a tiny dot in the ocean like Iwo Jima (think Amelia Earhart and how she missed Howland Island) and wind up having to ditch from running out of fuel, the tail warning radar allowed them to concentrate on fixing their position without the distraction of having to constantly "check 6" to make sure they weren't getting a nasty surprise from behind, it undoubtedly saved lives there not just from warning about an attack but also from giving a pilot the peace of mind he needed to concentrate on fixing his location so he could find his base.
@@redtobertshateshandles Yep, math is hard enough without a hand held electronic calculator much less having to do navigation mathematics while worrying about someone sneaking up behind you. The P47N pilots in the Pacific really had it nice, they not only had the tail warning radar but they also had an autopilot and seats with arm rests that folded down, they could really kick back and relax, all they lacked was an under the dash FM converter with the 8 Track player.
They are called Yagi antennas. Not so different from an old-fashioned rooftop VHF TV antenna, except that for TV you needed only receiving capability at home. The length of the rods is tuned to the wavelength of the radar, which is why a TV antenna had rods of differing length.
That antenna is surprisingly sophisticated. It's a folded dipole inside a 2D corner reflector (dummy dipole reflector + fin) guided with a single Yagi element. Yagi and Uda invented that concept in 1926.
The APS13 radar was the same as the Monica tail warning radar used by the RAF. It proved to be a liability at night because it could be homed in on by Luftwaffe night fighters fitted with Flensburg radar detectors. This wasn’t realised until the RAF captured an intact Ju88 night fighter in 1944.
This was great! I had no idea this existed during WW2. Very cool. I knew about range finding gun sights but didn't think they really became used until the Saber.
The problem with vacuum tube electronics is they have to warm up. In this case a three minute warm up. As a kid all TV sets had to have a minute before a picture was seen.
Well I've been watching WW2 docs for 20 something years now and I don't remember seeing or hearing about this. Every single video on this channel is worth watching.
My dad flew PBJs in the Pacific while in the USMC. So, naturally I loved anything aviation related to the war. I've read many books on European and Pacific Theater's of Operations. And I must say that this video is the first time of hearing about this radar. Truly ingenious. I knew about radar being used to direct fighters and on night fighters, but this is a first for me. Great video.
surprising video to see. I had one of those military surplus APS-13's back in 1961, I modified it so it could receive on UHF military aircraft frequencies and i could occasionally hear aircraft in the Los Angeles region, so, it actually worked as a receiver where I had earphones connected, and I built an antenna and placed that outside the window. The APS-13 was a nifty looking rig, funny looking tubes and silver plated inductors.
Thanks for the research and keeping history alive. I knew nothing of this although people may be aware of the RAF's tail warning radar, codename Monica.
@@philiphumphrey1548 The operational requirement for Monica was raised by RAF Bomber Command in June 1941. Due to shortages of CRT's and the fact that there was nobody on the Bomber Crew at the time who could watch a CRT display all of the time, an audio warning system was used in the intercom system's of some of the crew members (Pilot, Wireless Op and Gunners). The System was ready for wide scale deployment in late 1942, but it was then found to jam the OBOE system used by the Mosquito Pathfinders. Deployment was delayed until OBOE was modified to overcome the issue. The system worked fine when serviceable for aircraft operating on their own, but within a tightly packed Bomber Stream, it was going off all of the time and there was no practical method of putting some form of IFF into the system. So the Mark I version was a failure, as most crews switched it off, when it wasn't going unserviceable, which happened 20% of the time. The Withdraw from service of the 1.5 Metre band ASV Mk II radar in Coastal Command in 1943, saw the display systems form that equipment merged with the Monica system to create the Mk III "Visual" Monica system, which gave the wireless operator a visual indication of what was happening behind and below the aircraft and losses of aircraft in squadrons fitted with the kit were much lower than on squadrons fitted with the standard equipment. Even then, the equipment failure rate was around 20% pre sortie. Yes the German's built a Homing System, called Flensburg, but that didn't really roll out into wide spread use until April / May 1944 and the British got their hands on a working one in a Ju-88 in July 1944. British Trials using the captured aircraft showed that it could plot a large number of aircraft in bomber stream from long range. This totally destroyed the RAF's concept of decoy and spoof raids to spilt the defensive night fighter force and everybody would know which was the real bomber stream and what was the spoof's. Thus Monica was removed from the Main Force Heavies that operated in the Bomber Stream. Everybody else in Bomber Command who operated as single aircraft at night, kept it!! The 100 Group Bomber Support Mosquito Night Fighters, the 8 Group Mosquito Pathfinders and the 100 Group Fortress and Liberators on the high altitude RCM (jamming) missions. The Monica Kit on those aircraft allowed a great many evasions of interceptions to take place. The German's developed their own tail warning kit in late 1943 and fitted it to fighter bombers doing attacks on southern England. It made the lives of the RAF Mosquito units trying to intercept them a nightmare.
Great presentation, your use of primary sources is outstanding. I’m glad to linked your presentation with the use of these innovative systems with the first A bombs. You can see reconstructions of these devices at the Air Force museum in Ohio if you visit.
Great vid, my question would be, what was the % of US aircraft with this system by the end of the war? And how is it I have never heard of it? I learn so much from this channel!
As always, great video. However I believe the fighter action described at time 7:28 was a mustang. John Landers was flying “Big Beautiful Doll”, a pretty photogenic P-51.
I remember seeing aTV interview with elderly Russian pilots (after it came out that Russian pilots flew MiGs in Korea) where they said they had radar warning devices in their cockpits that worked much like modern Fuzzbusters. They warned then when an F-86 gunsight radar was illuminating them, so they could break away before the pilot started shooting.
CONUNDRUM: A difficult problem. I've been railing away at the shitty CG narrations cheap click-farmers use on their vids for years now. Unrelated, I keep clicking on your vids. Your sonorous recitation of straight facts is dead-on accurate and even varies in pitch and intonation enough to tell me you're a human just plying his trade honestly... But that "sonorous" bit- your voice makes me sleepy. I would have to be the most evil *#@!! EVAR to tell you to try CG narration (and I'm only half that evil, according to my Exes)... So I WON'T!! Don't change, Holmes! You're hard to keep up with (vs nodding off) but you're earnest and you're REAL. And that's just HUGE on this platform!! Thanks for all you do and how you do it! And if I'm wrong about you (CG vs human), can you please be the voice of the robot assassin sent to plug my Coppertop into the Matrix?
It drives home, really, how the Allied powers won the war. At a time when Germany was barely able to replace losses, and the Luftwaffe was becoming the punchline to bitter jokes by the ground forces they could no longer support, the Allied powers were not only leagues ahead in radar development but able to afford enough units to put two on every fighter aircraft to enhance both combat effectiveness and survivability.
Don't know about day fighters but do know British bomber aircraft with tail warning radar were easily 'homed in' on by German night-fighters who made use of that advantage with great success.
The German day fighters didn’t have radar, making it safer for the Allied day fighters to use it. Even if the German day fighters had only radar detectors, the emissions from the tail radar would only tell them the Allied opponent they were trying to sneak up on was probably going to break away at 800 yards but wouldn’t help them find them because they already knew where they were .
I reckon the Germans learned of the tail radar after having managed to shoot a plane equipped with one. Sort of interesting to consider the importance of inspecting every wrecked enemy plane to determine if any new tech was being used. Once the Germans discovered and determined the frequency, it was only a matter of time for them to begin tracking night bombers. I'd get a kick out of learning when this precisely happened. 🐿
@@Knuck_Knucks Your comment reminds of the fact that American aircrew members were expected to destroy their Norden bombsights long after many hundreds of examples in of that device (all kinds of conditions of course) were available to the Germans due to their access to shot down bombers. It would be interesting to read a detailed account of German reverse engineering and counter measures based on their detective work.
Great video! I knew of the device (as tailing warning in an aircraft), but not for long. But did not really know anything about it otherwise. Did not know it was the same unit as whatever 'The Bomb" had for altitude detection for detonation. Testing and adjusting the unit to set 'the gadget' off at the altitude that was wanted is pretty well shown in some Hollywood movie, though I haven't seen it in decades, I do remember that. Don't remember if they identified it in any manner.
Advanced stuff, especially considering the description for the line item about six above it on that same procurement page reads "PG-46-A loft for 60 or more pigeons"
Never knew about this, no wonder the late war planes were considered so successful. It was not necessarily the plane itself, but this little item helped out BUNCHES !
Thanks to miniaturization of electronics over the years, my bicycle today uses a tail warning radar that provides audible warning and graphical display of overtaking vehicles (including cyclists). Vehicles going the other way, or maintaining my pace or less, are ignored. The Garmin Varia RTL515 has about 1/8 the range (100 meters) of the WWII tail radars and runs for up to 15 hours (with taillight disabled) on one charge of its rechargeable battery. Complete system weight 71 grams; cost USD200. Like the fighter pilots, having tried this I don't want to ride without it. Overtaking vehicle speed and position data are stored on the bike computer for possible future retrieval and analysis. The radar beam seems cone shaped, maybe with round cross section instead of the elliptical shape of the aircraft radar.
It was fitted facing forwards to some single seat RAF aircraft to aid range perception when intercepting V1 flying bombs at night. The warning light was incorporated in the gun sight and illuminated when at 350 yards behind the flying bomb. Unfortunately, ground reflections below 1500 feet limited it’s usefulness.
The earliest I thought aircraft got ANY radar equipment was the late 50's early 60's. I am shocked that practically no one has heard of this. As as can be seen from the other commentators, I too am flabbergasted that I've never heard of this. This video was like striking gold in a sea of UA-cam World War II history videos. You can almost call it like a reverse radar warning receiver, where you're sending out the pulses in her waiting for them to come back to you. Instead of just the listening part. In World War II where I thought radar installations were at their infancy. but, if they managed to put one even a very rudimentary one that also only consumed about 97 watts, in the back of a fighter plane no less. Then maybe the technology wasn't as far into its infancy stage as I thought it was.
Cool, I knew they were experimenting with this kinda stuff but not that it had gone into production. 20 lbs added weight isn’t bad for WW2 era electronics.
My dad was a P51D Fighter Pilot in 1945 in the final stages of the war against Japan. He never saw any Japanese planes in the sky as they were all but finished by then. He never talked about the APS13 either maybe because it never alerted him. Would have liked to have known what he thought of it though.
Not really, the AN/APS-13 was an installation of the British Monica bomber rear alert radar system developed for the RAF, the VT-Fuze system was developed by the Telecommunications Research Establishment in England as part of the development of unrotated projectiles (rockets) for anti-aircraft use. The microwave replacement for the Monica system, the Fishpond auxiliary display was added to the H2S microwave based radar navigation system actually was a product of Bernard Lovell at the Telecommunications Research Establishment. So they both came from Britain but from seperate parts of the large radar development system.
This excellent video on a little-known subject made me want to know more. May I suggest a look at the Wiki "Monica" entry? This tail-warning radar was introduced in June 1942 and presumably gave some protection to bombers until compromised by the Germans in early 1944 (FuG 227 system). This was discovered by the RAF in July 1944 and Monica was removed. The American AN/APS-13 was itself a development of Monica ARI 5664 so the system was a success albeit its application on bombers was vulnerable to passive radar but that flaw didn't happen for 2 years. I read somewhere long ago that most pilots both in WW 1 and WW 2 were shot down by planes they never saw, mostly from their 6 o'clock. As the video says, the pilots were very keen on this system as fighter pilots were very vulnerable in the middle of combat when persuing enemy aircraft. For example, German ace Helmut Wick was shot down and killed in the B of B by Johnnie Dundas who was in turn immediately shot down and killed by Wick's wingman. As a side note, I read that MIG-15s in the Korean war were fitted with a passive tail radar to warn of the gun-laying radar of the Sabres. A never-ending battle of the beams...
Monica Mk 1 was wasn't rolled out until mid 1943. They found it jammed the OBOE blind bombing system and it wasn't fitted until OBOE was modified to overcome the issue (there only being 60 OBOE equipped aircraft in service at any one time (and almost one third of them were 9th Air Force B-26's!!!)). Monica Mk 1 was a failure. The system was designed for use by a single aircraft operating alone, as the RAF night bomber operated in 1941. On introduction, the equipment had a 20% per sortie failure rate, and the concentration of the RAF heavies into a tight compact bomber stream meant that the bombers carrying Monica were picking up friendly aircraft all of the time, most crews thought it was useless and turned it off. This issue was partly fixed with the introduction of Monica Mk 3, also known as Visual Monica, which included a CRT display system in the wireless operators position. This allowed the operator to determine if any of the the aircraft below and behind the bomber was trying to do an intercept and allow enough time for a corkscrew manoeuvre to be done, which normally resulted in a failed intercept. Monica wasn't removed from the Main Force bombers, because it made it easier for the Germans to find and shot down induvial bombers, it was removed because it made all of the Spoofing and Decoy Raids done by 100 Bomber Support group useless and the Germans could determine which raids were "Window" clouds and which raids were the Real Bomber Streams, by their Monica Transmissions. It was not removed from the Bomber Command Aircraft that operated alone (all Mosquitos and Fortress / Liberator RCM aircraft).
Sometime ago I read the autobiography of an RAF nightfighter radar operator whose Mosquito was fitted with Obo tail warning radar. He and his pilot came up with a clever idea which would set a trap for a German nightfighter using Obo. As they knew that range of the radar and had an idea of the approach speed of the German aircraft they would wait until the nightfright was close enough to them before snapping into a turn which would bring them up behind the German where they would shoot it down.
It is "Oboe" & it isn't a Tail Warning radar. Oboe radar was a British bomb aiming system developed to allow their aircraft to bomb targets accurately in any type of weather, day or night. Using TW radar on night mosquitoes to attract & outwit nightfighters was a common Mossie tactic.
Great hearing about the antique equipment used by WW2 planes and ships, particularly early warning systems. Wonder why this system was not deployed to bombers as well? For example, by 1945, the B-29 had remote controlled rear turrets with early TV sights. Since bombers are primary attacking targets for maraunding fighters, and getting on to the tail position is the most common form of aerial attack vector, this might have saved bomber crews as well by allowing them to evade tail attacks as well and to have the tail gunner improve his defensive fire effectiveness.
The US Tail Radar was a copy of the British Monica Tail Radar, design of which was started in 1941 and entered service in mid 1943. Worked OK on aircraft operating alone (if serviceable), but it was next to useless in a tight compact Bomber Stream as flown by Bomber Command in late 1943.
Man dad flew in the RAF - on Spitfires up until autumn 44 and then in April 45 he flew Mustangs in 19 squadron - But he never mentioned the system. But it sure looks smart ! and probably a great help. From about D-day his squadron mostly flew as fighter bombers, probably a lot of low flying. So maybe they did not have the system
Probably had to do with (lack of) receiver sensitivity. The 200 watts would have been only during the pulse transmit period so "average" power would have been much lower. "real" radars of the period had 1000's of watts output, but again these were only brief pulses.
@@howardeisenhauer1391 True; pulses have a lot of power. I looked up the 2D21 and it seems it could actually put out 200 watt pulses. It's a small 7 pin miniature thyratron. I count 19 tubes in that cabinet, I imagine it's pretty sensitive. Couldn't find a schematic.
Correction, The atomic bombs were triggered at an altitude to 1,800 feet, not 18,000 feet annotated in the video
Thanks for the great vid and correction. I always thought that was very practical the Manhattan project engineers used this off the shelf item for the final trigger.
Thanks for the correction, saved me a post.
AFAIK even 1800 was found to be too high - a lot of the atomic tests in the 1950s were "height vs yield" tests to determine the optimal height for bursts of various explosive yields. 1,800 feet was thought to have been too high for a European or North American style city but they used the higher altitude as they assumed that Japanese cities, being more flammable, would suffer more from a higher and thus more extensive blast radius.
The bomb was ground detonated by the Jesuit priests who survived (attributed, naturally, to a "miracle of Mary") at [close to] ground zero, underground. Both previous tests were ground based. They've carried on this lie for 80 years to scare the populace into compliance with defense budget spending. There is no such thing as airborne nuclear war. Sorry to burst the bubble.
I assumed that was what you meant as 18,000 feet burst height makes no sense for weapons of that yield. 18K feet was close to the burst height of the 50 MT Tsar Bomba (found it to be 4 km after a quick google search). For the limited yield of those early weapons 1,800 ft makes more sense.
Never heard of it in a WW2 fighter! Great content, thanks!
It had been used earlier in the war on British bombers and nightfighters to help against German nightfighters.
"Monica" it was called.
But, alas, german nightfighters soon learned of the device and developed a homing device, based on the beam this radar was creating!😮
Wow it's been years since I actually learned something about ww2 or the tech from that era. First time hearing of this device
MSD ..............I considered myself as a knowledgeable 71 year old of things WW 2 and with you on this ..........even knew a P 47 pilot who made thru the war .
I knew they were used on the tail turret of RAF Lancaster bombers to warn of approaching Luftwaffe night fighters. I guess the Lancaster was big enough to house the equipment and had multiple crew to operate the system (for example the Navigator’s station had a CRT display for the H2S radar) . But I never knew they were used on smaller, single seat, allied fighter aircraft.
@@notmenotme614 I also never new about this US system. But I have seen a couple of old RAF films about the "Village Inn" aka AGLT (automatic gun laying turret) system for British heavy bombers.
This is the first explanation of tail warning radar I've seen mentioned anywhere. Thank you.
Odd (not) that the video gives the impression it was an American Invention
Wow another thing I had no idea about this! Thanks!
Yes. Same here. What's really great about the system, based on my experience sailing using radar and AIS (identification radio signals). The false positive alerts: flak, drop tanks, friendlies, builds confidence in the system. The same is true with radar on a boat picking up a fishing buoy (Attraction device - more than just bobbing thing the size of a basketball). And the last listed advantage cannot be overstated. Enemies fighters do more than just shoot you down, that they exist and there's even the slight possibility get in behind you is a significant cognitive load and stressor that reduces how much concentration can be put on other aspects of the mission. Huge plus. The way a proximity warning system works on a boat is you can go to sleep knowing the system will wake you before any nearby vessel can be close enough to be a problem. If you don't have this even mid ocean where you might not see another vessel for weeks, you can't safely sleep more than about 45 minutes.
Tail warning radar on RAF night bombers was compromised and I believe deleted when it was found that Luftwaffe night fighters were using its emissions to find and home in on the same bombers. Perhaps more useful on fighters operating during the day?
The issue was the Flensburg system.
@@markstott6689 The monica tail warning radar (that the AN/APS-13 was copied from) was being withdrawn and was almost replaced with the more effective fishpond microwave system (an add on to H2S microwave radar navigation) by the time the RAF discovered the Flensburg system.
Fishpond had been developed and deployed rapidly in a response to an uptick in losses to nightfighters.
@@johnculver2519 Cool 😀
Interesting point. I've learned from these videos that the Germans didn't think microwave radar was even possible... Not sure how true this was, or what frequencies are involved in these two systems. Also this video does an excellent job presenting the logical reasoning used to create, deploy and understand this system. I wonder how effective was the reasoning of other WWII combatants developing their systems.
@@johnculver2519from what I’ve read fishpond when used correctly and when working correctly was very good 👍it allowed the bomber to suddenly corkscrew out of danger but wasn’t good at low altitudes as its coverage area was too small
Further Proof that " Radar" was one of the most important technologies used during WW2.
Not radar but magnetron
@@tedarcher9120
Magnatron technology was invented in the US by Albert Hall working at General Electric Research Laboratory, circa 1912, it was further developed in the US by A.L. Samuel of Bell Laboratories in 1934.
The CAVITY magnatron, a variation of magnatron technology, was introduced by John Randall and Harry Boot of the University of Birmingham in 1940.
@@tedarcher9120 No, the magnetron brought over to the US by Tizard made microwave *generation* practical, but it was the work of I I Rabi's Rad Lab that made radar *receivers* effective. The Rad Lab made a much bigger contribution to winning the war than the Manhattan Project.
The US had klystrons, but they were too heavy, complex and low power to make effective fighter based radar.
@@dukecraig2402 What Hall invented was nothing to do with radar at all, it was simply a valve that used a magnetic field to modulate the anode current.
The cavity magnetron was invented in Germany in 1935 but the Germans failed to exploit it due, basically, to a lack of imagination. Randall and Boot solved the technical problems and a 20kW magnetron was sent to the USA with the Tizard mission. This rapidly led to improvements in radar. The Germans never got past klystrons, which the USA was using until Tizard, which were limited to tens or hundreds of watts.
On your logic Thompson invented the magnetron in the 19th century because he used magnetic fields to bend the electron beam in his cathode ray tube.
@EbenBransome
It's not "my logic" and I never said anything about who invented radar, did I?
I was simply pointing out steps of magnatron development for the sake of those who think that the cavity magnatron was the start of everything magnatron, it wasn't, and the cavity magnatron wasn't the start of radar either nor is it exclusive to radar, radar already existed before the cavity magnatron, what the cavity magnatron did was make much smaller radar sets possible.
Considering the amount of German aces who specialized in getting in sniffing distance to the rear before pumping out the 20mm, it makes a lot of sense this would have an impact.
These systems were probably more useful in the Pacific where a fighter pilot who got separated from everyone else didn't have reference points on the ground like pilots in Europe did and had to concentrate on fixing his location so he could find his way back to a tiny dot in the ocean or ditch from running out of fuel, it gave them the peace of mind to concentrate on the math of navigation without constantly having to worry about someone sneaking up behind him.
@@dukecraig2402 there was a radio signal coming from the aircraft carriers to help the fighters find their way back home
@@sliceofbread2611
Sorry, when I mentioned a "tiny dot in the ocean" I should have included the word "island" as I did in another post here, I was talking about the land based Army fighter's, whether or not the Navy and Marine land based fighters in the Pacific ever had this system (or even their carrier based fighters for the sake of rear attacks) I don't know, I've never heard an account of them having them but that doesn't mean they didn't.
These systems were particularly useful on fighters in the Pacific where they were flying over water and didn't have navigation reference points on the ground like the fighters in Europe did, flying over water in the Pacific meant that they had to occupy themselves with their little navigation computers (not electronic computers, the little circular "pinwheel" calculator navigation devices) to figure their position, one little mistake and a fighter pilot who was on his own after getting separated from the rest could easily miss a tiny dot in the ocean like Iwo Jima (think Amelia Earhart and how she missed Howland Island) and wind up having to ditch from running out of fuel, the tail warning radar allowed them to concentrate on fixing their position without the distraction of having to constantly "check 6" to make sure they weren't getting a nasty surprise from behind, it undoubtedly saved lives there not just from warning about an attack but also from giving a pilot the peace of mind he needed to concentrate on fixing his location so he could find his base.
Yep.
One cloud, obscuring one tiny island 🏝 , in a huge ocean and you're in big trouble.
@@redtobertshateshandles
Yep, math is hard enough without a hand held electronic calculator much less having to do navigation mathematics while worrying about someone sneaking up behind you.
The P47N pilots in the Pacific really had it nice, they not only had the tail warning radar but they also had an autopilot and seats with arm rests that folded down, they could really kick back and relax, all they lacked was an under the dash FM converter with the 8 Track player.
An American fighter aircraft rear warning radar in WW2. A WW2 buff that never heard of this. Fascinating.
That's because it's not American. It's British, and AN/APS-13 is just what the Yanks called the Monica system that the British first built in 1942.
yes - adopted from the British system, with a much smaller (and also more accurate) wavelength than the German nightfighters used over Europe
Sir, your professionalism and attention to detail is awesome! Thank you for sharing this with us.
You are never too old to learn something new!
Thank you!!!
The old timey specifications get me. Frequency = 415 mc/s. That's 415 MHz for modern humans.
feet ! I'm British, so here that is amusing.
I noticed the 95 watts. 😂
Hertz was a German scientist of recent memory. It was patriotic to refer to them as "cycles" instead.
@@frederf3227 Names were changed by an international committee in 1968. Centigrade was also changed to Celsius.
Cycles are better than Hertz. We ain't German.
I learn something new every time I watch one of these videos.
A very informative video - thank you so much!
I had always noticed the antenna arrays on the atomic bombs, but never knew their significance.
They are called Yagi antennas. Not so different from an old-fashioned rooftop VHF TV antenna, except that for TV you needed only receiving capability at home. The length of the rods is tuned to the wavelength of the radar, which is why a TV antenna had rods of differing length.
Try getting this on the History Channel. Great stuff I'd never know otherwise.
Another interesting aspect of WW2 that I never heard of before. Bravo!
That antenna is surprisingly sophisticated. It's a folded dipole inside a 2D corner reflector (dummy dipole reflector + fin) guided with a single Yagi element. Yagi and Uda invented that concept in 1926.
I have seen this antenna in photos in the past on tails and A-bomb pix...but never knew what it was. Thanks so much for this information!
Great video, man! This is something rarely covered or discussed
I like that the P-61 night fighter had top priority on the list. Big radar upfront and a little radar in back.
The APS13 radar was the same as the Monica tail warning radar used by the RAF. It proved to be a liability at night because it could be homed in on by Luftwaffe night fighters fitted with Flensburg radar detectors. This wasn’t realised until the RAF captured an intact Ju88 night fighter in 1944.
I had no idea that this system existed, thank you very much for teaching me something new today!
always super informative, always loved planes and never new this, great job
I never knew! Great video. Always learning from this channel. Sincerely hope YT is rewarding you for this historical content!
This was great! I had no idea this existed during WW2. Very cool. I knew about range finding gun sights but didn't think they really became used until the Saber.
Add it to the long list of things I didn't know existed until WWII US Bombers
The problem with vacuum tube electronics is they have to warm up. In this case a three minute warm up. As a kid all TV sets had to have a minute before a picture was seen.
Even vacuum tube car radios had to warm up. Start the car and the radio comes on half way down the block.
@WWIIUSBombers >>> Great video...👍
No Doubt.
Great stuff as always WW2USB.
Never knew that was a thing.
Excellent video, as usual. Thanks!
Well I've been watching WW2 docs for 20 something years now and I don't remember seeing or hearing about this. Every single video on this channel is worth watching.
I read that German night fighters learned to use this tail radar system to track allied bombers
This is sooo fantastic.
You are covering all kinds of super important technology, which seems to have had scant treatment elsewhere.
Id heard mentions of tail warning radar but didn't know anything else about it. Awesome video!
Excellent again you are one of the best channels on UA-cam for real. 👍🇭🇲
Good explanation of the tail warning radar system on P-47's and P-51's.
Thanks a lot ! Technical development was very rapid during war and production fast.
Very interesting! As always, love your primary source material.
My dad flew PBJs in the Pacific while in the USMC. So, naturally I loved anything aviation related to the war. I've read many books on European and Pacific Theater's of Operations. And I must say that this video is the first time of hearing about this radar. Truly ingenious. I knew about radar being used to direct fighters and on night fighters, but this is a first for me. Great video.
FD8............knew a T- bolt pilot and with you bro
Small world. I flew PBJs in school lunches just about every day.
fascinating, had never heard of this device
Yet another outstanding 'deep dive'... thank you !!
Great content, enjoyable and informative, so good job and keep it coming
surprising video to see. I had one of those military surplus APS-13's back in 1961, I modified it so it could receive on UHF military aircraft frequencies and i could occasionally hear aircraft in the Los Angeles region, so, it actually worked as a receiver where I had earphones connected, and I built an antenna and placed that outside the window. The APS-13 was a nifty looking rig, funny looking tubes and silver plated inductors.
Never knew about this, thx! Always enjoy your vids!
Thanks for the research and keeping history alive. I knew nothing of this although people may be aware of the RAF's tail warning radar, codename Monica.
Monica was a failure, the Luftwaffe's night fighters got wise to it and used Monica's transmissions to home in on the bombers.
@@philiphumphrey1548 Obviously less important on a day fighter. But wasn’t that the role of the wingman?
@@ronhudson3730but then who’s protecting the wingman?
@@philiphumphrey1548 The operational requirement for Monica was raised by RAF Bomber Command in June 1941. Due to shortages of CRT's and the fact that there was nobody on the Bomber Crew at the time who could watch a CRT display all of the time, an audio warning system was used in the intercom system's of some of the crew members (Pilot, Wireless Op and Gunners).
The System was ready for wide scale deployment in late 1942, but it was then found to jam the OBOE system used by the Mosquito Pathfinders. Deployment was delayed until OBOE was modified to overcome the issue. The system worked fine when serviceable for aircraft operating on their own, but within a tightly packed Bomber Stream, it was going off all of the time and there was no practical method of putting some form of IFF into the system.
So the Mark I version was a failure, as most crews switched it off, when it wasn't going unserviceable, which happened 20% of the time.
The Withdraw from service of the 1.5 Metre band ASV Mk II radar in Coastal Command in 1943, saw the display systems form that equipment merged with the Monica system to create the Mk III "Visual" Monica system, which gave the wireless operator a visual indication of what was happening behind and below the aircraft and losses of aircraft in squadrons fitted with the kit were much lower than on squadrons fitted with the standard equipment. Even then, the equipment failure rate was around 20% pre sortie.
Yes the German's built a Homing System, called Flensburg, but that didn't really roll out into wide spread use until April / May 1944 and the British got their hands on a working one in a Ju-88 in July 1944. British Trials using the captured aircraft showed that it could plot a large number of aircraft in bomber stream from long range. This totally destroyed the RAF's concept of decoy and spoof raids to spilt the defensive night fighter force and everybody would know which was the real bomber stream and what was the spoof's.
Thus Monica was removed from the Main Force Heavies that operated in the Bomber Stream. Everybody else in Bomber Command who operated as single aircraft at night, kept it!! The 100 Group Bomber Support Mosquito Night Fighters, the 8 Group Mosquito Pathfinders and the 100 Group Fortress and Liberators on the high altitude RCM (jamming) missions. The Monica Kit on those aircraft allowed a great many evasions of interceptions to take place.
The German's developed their own tail warning kit in late 1943 and fitted it to fighter bombers doing attacks on southern England. It made the lives of the RAF Mosquito units trying to intercept them a nightmare.
Great presentation, your use of primary sources is outstanding. I’m glad to linked your presentation with the use of these innovative systems with the first A bombs. You can see reconstructions of these devices at the Air Force museum in Ohio if you visit.
Great vid, my question would be, what was the % of US aircraft with this system by the end of the war? And how is it I have never heard of it? I learn so much from this channel!
As always, great video. However I believe the fighter action described at time 7:28 was a mustang. John Landers was flying “Big Beautiful Doll”, a pretty photogenic P-51.
I had never heard of this ! I wonder if F-86's had this in Korea 🤔
I remember seeing aTV interview with elderly Russian pilots (after it came out that Russian pilots flew MiGs in Korea) where they said they had radar warning devices in their cockpits that worked much like modern Fuzzbusters. They warned then when an F-86 gunsight radar was illuminating them, so they could break away before the pilot started shooting.
Great unusual information.
Great production as usual.
👏🏻👏🏻👏🏻⚡🥃
GOAT ww2 aviation channel
Excellent video!!! I knew about the atomic bomb altitude radar, but had no clue that it had been applied to aircraft for tail warning.
Very interesting. I never knew this was available for pilots. Thanks
Great video! Would love more Electric Warfare & EC videos in the future!
Wow I learned so much from this. Thank you so much!!!
Was this system continued on later post-war fighters?
CONUNDRUM: A difficult problem.
I've been railing away at the shitty CG narrations cheap click-farmers use on their vids for years now.
Unrelated, I keep clicking on your vids. Your sonorous recitation of straight facts is dead-on accurate and even varies in pitch and intonation enough to tell me you're a human just plying his trade honestly...
But that "sonorous" bit- your voice makes me sleepy. I would have to be the most evil *#@!! EVAR to tell you to try CG narration (and I'm only half that evil, according to my Exes)... So I WON'T!!
Don't change, Holmes! You're hard to keep up with (vs nodding off) but you're earnest and you're REAL. And that's just HUGE on this platform!!
Thanks for all you do and how you do it!
And if I'm wrong about you (CG vs human), can you please be the voice of the robot assassin sent to plug my Coppertop into the Matrix?
Very cool! I had no idea this technology was in place that long ago!
It drives home, really, how the Allied powers won the war. At a time when Germany was barely able to replace losses, and the Luftwaffe was becoming the punchline to bitter jokes by the ground forces they could no longer support, the Allied powers were not only leagues ahead in radar development but able to afford enough units to put two on every fighter aircraft to enhance both combat effectiveness and survivability.
This channel is precisely my level of history, nerd and aviation combined. It is like a “How’s it made” Hx Edition without the cringy puns
Don't know about day fighters but do know British bomber aircraft with tail warning radar were easily 'homed in' on by German night-fighters who made use of that advantage with great success.
The German day fighters didn’t have radar, making it safer for the Allied day fighters to use it. Even if the German day fighters had only radar detectors, the emissions from the tail radar would only tell them the Allied opponent they were trying to sneak up on was probably going to break away at 800 yards but wouldn’t help them find them because they already knew where they were
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I reckon the Germans learned of the tail radar after having managed to shoot a plane equipped with one. Sort of interesting to consider the importance of inspecting every wrecked enemy plane to determine if any new tech was being used. Once the Germans discovered and determined the frequency, it was only a matter of time for them to begin tracking night bombers. I'd get a kick out of learning when this precisely happened. 🐿
@@Knuck_Knucks Your comment reminds of the fact that American aircrew members were expected to destroy their Norden bombsights long after many hundreds of examples in of that device (all kinds of conditions of course) were available to the Germans due to their access to shot down bombers. It would be interesting to read a detailed account of German reverse engineering and counter measures based on their detective work.
A 20 lb. “Wingman” to alert you to a rearward threat? Awesome, especially for those days.
And this is when the term "watch you 6" began to fade into obscurity. 🐿
Great video! I knew of the device (as tailing warning in an aircraft), but not for long. But did not really know anything about it otherwise. Did not know it was the same unit as whatever 'The Bomb" had for altitude detection for detonation. Testing and adjusting the unit to set 'the gadget' off at the altitude that was wanted is pretty well shown in some Hollywood movie, though I haven't seen it in decades, I do remember that. Don't remember if they identified it in any manner.
I never had heard of that before , nice content
Never heard of this , Thanks.
I never heard of this. Very good.
I had never heard of that. Very interesting
Advanced stuff, especially considering the description for the line item about six above it on that same procurement page reads "PG-46-A loft for 60 or more pigeons"
something i never knew existed.
thanks!
Wow your good !
Fascinating stuff - Thanks !
😎👍
Thanks, a great informative video.
That was actually really cool.
This episode would be complemented nicely if you would do another on Allied and Axis IFF systems.
Much better than the rear view cockpit mirror😂😂
Ahh, always wondered what the antennas were on the Little Boy were for ?? - mystery solved ! ;) Thanks
Never knew about this, no wonder the late war planes were considered so successful. It was not necessarily the plane itself, but this little item helped out BUNCHES !
good video. the electronic Warfare is a good theme for various videos.
This AN/APS radar should be added to planes in IL-2 Sturmovik simulator, and to War Thunder.
Never knew this!
I always learn something.
I'm surprised this feature went away for Korea era, and even Vietnam. It would still have been useful.
Thanks to miniaturization of electronics over the years, my bicycle today uses a tail warning radar that provides audible warning and graphical display of overtaking vehicles (including cyclists). Vehicles going the other way, or maintaining my pace or less, are ignored. The Garmin Varia RTL515 has about 1/8 the range (100 meters) of the WWII tail radars and runs for up to 15 hours (with taillight disabled) on one charge of its rechargeable battery. Complete system weight 71 grams; cost USD200. Like the fighter pilots, having tried this I don't want to ride without it. Overtaking vehicle speed and position data are stored on the bike computer for possible future retrieval and analysis. The radar beam seems cone shaped, maybe with round cross section instead of the elliptical shape of the aircraft radar.
It was fitted facing forwards to some single seat RAF aircraft to aid range perception when intercepting V1 flying bombs at night. The warning light was incorporated in the gun sight and illuminated when at 350 yards behind the flying bomb. Unfortunately, ground reflections below 1500 feet limited it’s usefulness.
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The earliest I thought aircraft got ANY radar equipment was the late 50's early 60's. I am shocked that practically no one has heard of this. As as can be seen from the other commentators, I too am flabbergasted that I've never heard of this. This video was like striking gold in a sea of UA-cam World War II history videos. You can almost call it like a reverse radar warning receiver, where you're sending out the pulses in her waiting for them to come back to you. Instead of just the listening part. In World War II where I thought radar installations were at their infancy. but, if they managed to put one even a very rudimentary one that also only consumed about 97 watts, in the back of a fighter plane no less. Then maybe the technology wasn't as far into its infancy stage as I thought it was.
Cool, I knew they were experimenting with this kinda stuff but not that it had gone into production. 20 lbs added weight isn’t bad for WW2 era electronics.
My dad was a P51D Fighter Pilot in 1945 in the final stages of the war against Japan. He never saw any Japanese planes in the sky as they were all but finished by then. He never talked about the APS13 either maybe because it never alerted him. Would have liked to have known what he thought of it though.
Is it true that the AN/APS-13 was a spinoff of the work done on proximity fuses?
Not really, the AN/APS-13 was an installation of the British Monica bomber rear alert radar system developed for the RAF, the VT-Fuze system was developed by the Telecommunications Research Establishment in England as part of the development of unrotated projectiles (rockets) for anti-aircraft use.
The microwave replacement for the Monica system, the Fishpond auxiliary display was added to the H2S microwave based radar navigation system actually was a product of Bernard Lovell at the Telecommunications Research Establishment.
So they both came from Britain but from seperate parts of the large radar development system.
@@johnculver2519 thanks
This excellent video on a little-known subject made me want to know more. May I suggest a look at the Wiki "Monica" entry? This tail-warning radar was introduced in June 1942 and presumably gave some protection to bombers until compromised by the Germans in early 1944 (FuG 227 system). This was discovered by the RAF in July 1944 and Monica was removed. The American AN/APS-13 was itself a development of Monica ARI 5664 so the system was a success albeit its application on bombers was vulnerable to passive radar but that flaw didn't happen for 2 years.
I read somewhere long ago that most pilots both in WW 1 and WW 2 were shot down by planes they never saw, mostly from their 6 o'clock. As the video says, the pilots were very keen on this system as fighter pilots were very vulnerable in the middle of combat when persuing enemy aircraft. For example, German ace Helmut Wick was shot down and killed in the B of B by Johnnie Dundas who was in turn immediately shot down and killed by Wick's wingman.
As a side note, I read that MIG-15s in the Korean war were fitted with a passive tail radar to warn of the gun-laying radar of the Sabres. A never-ending battle of the beams...
Monica Mk 1 was wasn't rolled out until mid 1943. They found it jammed the OBOE blind bombing system and it wasn't fitted until OBOE was modified to overcome the issue (there only being 60 OBOE equipped aircraft in service at any one time (and almost one third of them were 9th Air Force B-26's!!!)). Monica Mk 1 was a failure. The system was designed for use by a single aircraft operating alone, as the RAF night bomber operated in 1941. On introduction, the equipment had a 20% per sortie failure rate, and the concentration of the RAF heavies into a tight compact bomber stream meant that the bombers carrying Monica were picking up friendly aircraft all of the time, most crews thought it was useless and turned it off.
This issue was partly fixed with the introduction of Monica Mk 3, also known as Visual Monica, which included a CRT display system in the wireless operators position. This allowed the operator to determine if any of the the aircraft below and behind the bomber was trying to do an intercept and allow enough time for a corkscrew manoeuvre to be done, which normally resulted in a failed intercept.
Monica wasn't removed from the Main Force bombers, because it made it easier for the Germans to find and shot down induvial bombers, it was removed because it made all of the Spoofing and Decoy Raids done by 100 Bomber Support group useless and the Germans could determine which raids were "Window" clouds and which raids were the Real Bomber Streams, by their Monica Transmissions. It was not removed from the Bomber Command Aircraft that operated alone (all Mosquitos and Fortress / Liberator RCM aircraft).
Nice! I had no idea!
Sometime ago I read the autobiography of an RAF nightfighter radar operator whose Mosquito was fitted with Obo tail warning radar. He and his pilot came up with a clever idea which would set a trap for a German nightfighter using Obo. As they knew that range of the radar and had an idea of the approach speed of the German aircraft they would wait until the nightfright was close enough to them before snapping into a turn which would bring them up behind the German where they would shoot it down.
It is "Oboe" & it isn't a Tail Warning radar. Oboe radar was a British bomb aiming system developed to allow their aircraft to bomb targets accurately in any type of weather, day or night. Using TW radar on night mosquitoes to attract & outwit nightfighters was a common Mossie tactic.
Great hearing about the antique equipment used by WW2 planes and ships, particularly early warning systems. Wonder why this system was not deployed to bombers as well? For example, by 1945, the B-29 had remote controlled rear turrets with early TV sights. Since bombers are primary attacking targets for maraunding fighters, and getting on to the tail position is the most common form of aerial attack vector, this might have saved bomber crews as well by allowing them to evade tail attacks as well and to have the tail gunner improve his defensive fire effectiveness.
The US Tail Radar was a copy of the British Monica Tail Radar, design of which was started in 1941 and entered service in mid 1943. Worked OK on aircraft operating alone (if serviceable), but it was next to useless in a tight compact Bomber Stream as flown by Bomber Command in late 1943.
One of the issues is that pilots would get focused on their attacks and forget about someone on their tail.
Man dad flew in the RAF - on Spitfires up until autumn 44 and then in April 45 he flew Mustangs in 19 squadron - But he never mentioned the system. But it sure looks smart ! and probably a great help. From about D-day his squadron mostly flew as fighter bombers, probably a lot of low flying. So maybe they did not have the system
It was detectable by the Luftwaffe & therefore of limited use. I doubt it reduced losses by 80% as claimed here.
Found out about this thing watching people play DCS. Wondered what this light with a bell was until the guy playing mentioned the system.
Hard to imagine such a little thing could put out 200 watts, or why so much power would be needed for such a short range.
Probably had to do with (lack of) receiver sensitivity. The 200 watts would have been only during the pulse transmit period so "average" power would have been much lower. "real" radars of the period had 1000's of watts output, but again these were only brief pulses.
@@howardeisenhauer1391 True; pulses have a lot of power. I looked up the 2D21 and it seems it could actually put out 200 watt pulses. It's a small 7 pin miniature thyratron. I count 19 tubes in that cabinet, I imagine it's pretty sensitive. Couldn't find a schematic.
And, back then I also learned that the APS-13 was called the 'Tail End Charlie.
Thank you for this excellent aircraft Radar protecting my 6 o'clock
Old F-4 pilot Shoe🇺🇸
I never knew about this!