Geezer
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How Aircraft Were Detected Before Radar & WW 2

Wed Mar 02, 2011 7:46 am

I have a friend who is a historian; as he knows I'm interested in military history, he sends me a lot of "stuff"; This is how they "detected" (or tried to detect) enemy planes before and during early WW 2
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Geezer
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RE: How Aircraft Were Detected Before Radar & WW 2

Wed Mar 02, 2011 8:13 am

Getting these rare old images on here really was a chore ! I'm sorry I wasn't able to keep any information with individual photos. I believe one of these "inventions" may be of Japanese origin, some are British, some are American, and at least one is French. So as you can see, there were many people from many countries trying to come up with means to detect oncoming enemy aircraft over a considerable time period, a long time before Radar was developed by the Brits in early WW 2.

When I first received these photos, I assumed they were all from the late 1930's to the early 1940's, but upon closer inspection, ( and wracking my somewhat slow-working memory as to what I could remember from newspapers, news magazines, and news reels at the movies, I think a few of these probably date back to World War 1 )

I hope you enjoy them as much as I did.

Charley
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WingsFan
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RE: How Aircraft Were Detected Before Radar & WW 2

Wed Mar 02, 2011 9:46 am

Very interesting.
I had read about these things before, but only after seeing these rare pictures can I appreciate how elaborate some of these are.

Thanks for sharing.

WingsFan
 
sphealey
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RE: How Aircraft Were Detected Before Radar & WW 2

Wed Mar 02, 2011 12:07 pm

The UK also had a chain of permanent listening stations with guide tubes made of concrete; I have seen pictures on various web sites and I believe some of the listening posts still stand (being difficult to demolish!).

I've wondered if anyone has considered trying to revive this technology as a counter to stealth. Seems as if it would work a lot better with a network of GPS-synchronized listening posts spread across a wide area.

sPh
 
ferpe
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RE: How Aircraft Were Detected Before Radar & WW 2

Wed Mar 02, 2011 1:03 pm

Great stuff, these all used the human ear to listen for aircraft. There where also some very embryotic developments of IR sensors to try and use these as detector of aircraft but they only could give direction, were weather dependant and had short range.

Radar development for the RAF started in 1934 with the first experiment using a normal radio transmitter as the transmitter and a Van with a reciever equipment placed a bit by the side. They could measure the difference in signal when a plane passed in front of the arrangement and reflected the signal to the recieving van. The frequency was 27 Mhz. From these simple experiments one built dedicated transmitters and receivers using TV frequencies as the knowhow and components to make TV transmitters and receivers where available (approx 35 Mhz).

The operational radard started deployment just before WW2 as Chain Home and it's amazing that it acutally allowed 3D position determination of approaching aircraft. Chain Home most probably saved UK from a German invasion one year intor the war as the Brits had been smart enough to build a complete command and control systems around it, they could really economise with the fighters, only scrambling them when and to where necessary.
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oly720man
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RE: How Aircraft Were Detected Before Radar & WW 2

Wed Mar 02, 2011 1:59 pm

Quoting geezer (Thread starter):

Interesting photos. The first one is Japanese, apparently

http://www.design-technology.info/inventors/page29.htm

Some other pictures of the concrete bowl "acoustic mirrors" from the UK in the above link.
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GAIsweetGAI
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RE: How Aircraft Were Detected Before Radar & WW 2

Wed Mar 02, 2011 4:58 pm

Quoting sphealey (Reply 3):
I've wondered if anyone has considered trying to revive this technology as a counter to stealth

If the aircraft is going supersonic, stealth or not, it'll be over your head before you can hear it.   
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frmrCapCadet
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RE: How Aircraft Were Detected Before Radar & WW 2

Wed Mar 02, 2011 5:16 pm

An uncle and a MIL (still living) were 'spotters' during WWII. Visual only. They weren't but some experienced spotters were really good, from what I hear.
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LMP737
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RE: How Aircraft Were Detected Before Radar & WW 2

Wed Mar 02, 2011 5:42 pm

Any pictures of the MK 1 eyeball?  
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Confuscius
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RE: How Aircraft Were Detected Before Radar & WW 2

Wed Mar 02, 2011 7:06 pm

Quoting LMP737 (Reply 8):
Any pictures of the MK 1 eyeball?

See image below...

V


V


V


V


V


  

[Edited 2011-03-02 11:09:52]
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MD11Engineer
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RE: How Aircraft Were Detected Before Radar & WW 2

Wed Mar 02, 2011 8:09 pm

the British WW2 system worked with two coastal radar systems, the "Chain home" and the "Chain home low" and, for the airspace inlands of the coast, a "Royal Observer Corps, which used traditional methods. like visual silouette recognition, to report aircraft movements via telephone to fighter command HQ.
Chain home consisted of towers along the coast, between which antenna wires were stretched.
Transmission and reception antennas were set up seperately. The transmission antennas provided a fixed "searchlight beam", illuminating a sector of azimut, while the nearby two reception antennas were directional and mounted at an angle. Comparing the signal strength and phase difference received by these two antennas on an oscilloscope gave the rough direction of the target. Altitude of the targets was determined by again comparing the signal strength between two antennas located at different heigth on the towers. In any case, since the frequencies were between 20 and 50 MHz (usually between 20 and 30 MHz, about what CB radio operators use today), the resolution was not great. But the range was several hundred km, so that German aircraft could be recognised while they were still in the assembly areas over France or the Low Countries. Essentially the Chain Home was an early warning radar.
Only the towers of one station above Dover survive today, all others have been scrapped after WW2.

The Chain Home Low used rotating directional antennas at a frequency of 200 MHz. While the range was much lower (about 50 km or so), the resolution was much better, so that the size of the enemy aircraft unit could be determined.

After the aircraft crossed the coastline, there was no radar coverage. The Royal Observer Corps had posts e.g. on hilltops and high buildings all over the country. They would identify aircraft visually and determine their altitude and course using a simple transit. The results would be phoned (like the sightings by the radar stations) to the local HQ (which would filter the information) and then sent to Fighter Command HQ in IIRC Biggin Hill.

Jan

Edit:

This is a typical Chain home station with the transmission towers in the foreground and the receiving antenna towers in the back:


The operator would see something like this:


The Plan Position Indicator (which is what we know as a radar screen today) only came up with the centrimetric H2S airborne ground surveillance and bomb aiming radar, which was e.g. used on Lancaster bombers:


All pictures borrowed from http://www.alpha60.de/research/muc/DavidLink_RadarAngels_EN.htm


Jan

[Edited 2011-03-02 12:47:36]
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flyingwaeldar
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RE: How Aircraft Were Detected Before Radar & WW 2

Thu Mar 03, 2011 3:59 am

Some more information regarding the acoustic listening devices can be found here:

http://douglas-self.com/MUSEUM/COMMS/ear/ear.htm

A lot of other interesting technical stuff at that site as well.
 
sphealey
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RE: How Aircraft Were Detected Before Radar & WW 2

Sat Mar 05, 2011 1:44 am

Quoting flyingwaeldar (Reply 11):
Some more information regarding the acoustic listening devices can be found here:

Thanks; that link had a picture of one of the permanent listening stations in the UK.

sPh

Not sure how the discussion got diverted from audible-frequency detection to the Chain Home radar system?

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