A History of Night Flying, Part Two: World War II (1939-1945)

A Boeing 307 Stratoliner from the World War II era. The Stratoliner was the first airliner to be pressurized, enabling it to fly at high altitudes.

In case you missed my first blog post about the history of night flying, you can read that here. Now on to part two: Night flying during the World War II years.

Regular “red-eye flight” services as we know them now were still not possible during the 1940s due to the lack of availability of night-flying equipment, the inability of most airliners to fly long distances, and so on. Obviously the war and the very high possibility of being shot down by either side while flying over occupied Europe or the Asia-Pacific region would make flying at night very risky. However, it was during this period of time that the technology that made routine night flying possible was born……

US paratroopers of the 101st Airborne Division heading toward British Hotspur gliders during training exercises.
















During the war, fighters and bombers on both sides launched attacks on ground targets, military installations, cities. and enemy aircraft at night. When the war broke out in 1939, the methods used for night flying – especially on the British side – were very crude compared with the technology available to them by the war’s end. Some of the main methods used by the RAF at the onset of the war had been used by navigators for many centuries.

Military Night Flights and Celestial Navigation
At the outbreak of war, American, British, and Japanese military pilots navigated at night mostly by using the time-tested, old-fashioned way: Celestial navigation. With a sextant and star charts and by the light of the moon, the pilots made their way to their targets across occupied Europe and the Pacific. On a cloudy or foggy night, it was sometimes impossible to tell friend from foe. Japanese pilots would continue to fly this way at night throughout most of the war.

Devices such as the Mark 1B astrograph (used by both American and British air forces), the A-10A sextant used by the US Army Air Force made flying by the stars, and the Fairchild-Maxon Mark I Line of Position Computer used by USAAF and US Navy aircraft made night flying much easier. However, the Mark 1B and Fairchild-Maxon computers were far too heavy for most navigators and pilots to deal with and the Fairchild-Maxon computers were also very expensive.

The navigator of a bomber would often sit in the glass “bubble” (often sharing it with the bombardier or tail gunner) and make his calculations where he’d have a good view of the night sky and the ground below.

The German Luftwaffe, on the other hand, had its own special innovative night-flying technology which will be discussed in detail below.

Clandestine Operations at Night
Throughout the war, both sides used the darkness of night as a natural cover to launch clandestine operations into each others’ territory. On the Allied side, C-47s and paratroop gliders dropped paratroopers, commandos, and secret agents behind enemy lines during the nighttime hours. Soviet airline Aeroflot carried out over 83,000 special nighttime missions by the time the war officially ended in September, 1945.

A German Be 09 “Bernhard” navigation antenna from WWII.


Wartime Technological Advancements and Night Flying
It has often been said that World War II was a “technological war.” New technological developments were put to the test during the war and these developments changed the world. Some of these developments are still changing the world at this very moment. Needless to say, all the new technological developments of the WWII era made flying at night much, much easier.

Blind Flying Navigation Systems
Prior to the outbreak of war, new technologies were being developed that made flying at night a whole lot easier. Blind flying beams such as the Lorenz beam in Germany and the Diamond-Dunmore equi-signal radio guidance system in the US guided planes to the ground during the night and in bad weather conditions when visibility was down to a bare minimum. The Lorenz beam consisted of two different signals: A signal that transmitted Morse code dots, and another signal that transmitted Morse code dashes. All three were broadcast from a single radio transmitter via three antennae at the end of an airport runway. As a pilot came in for a landing, the main signal got stronger. If s/he veered off course to the left, s/he would hear the Morse code dots. If off course to the right, s/he would hear the dashes. If they were making a smooth landing, the signals would both align to form a single equisignal.

Before the war, the Lorenz beam was used by airports in several countries including Germany and Switzerland. It was used by Lufthansa as early as 1934 and would be used some 6-7 years later after the outbreak of World War II by the Luftwaffe as their main pilot guidance system to targets across the UK during the Blitz. Lorenz beams were picked up by special radio receivers installed in Luftwaffe aircraft known as Knickebein (“Crooked leg” in German) devices due to the crooked shape of the antenna which protruded from underneath the airplane.

The Battle of the Beams, or the British effort to jam the Lorenz transmissions and send out misleading transmissions, was a large-scale battle fought behind the scenes during the Battle for Britain!

After the war, the Lorenz technology was confiscated by the Allies and was put to good use by US, British and Soviet airlines until instrument landing systems came along during the 1950s and rendered the Lorenz beam obsolete.

The two main systems developed by the Allies were the Gee system and LORAN. The Gee system was developed by scientists in Britain, while the LORAN system was developed by American scientists. Both were very similar to each other. So much so that the two devices could be interchanged! These radio navigation systems made it possible for planes to find their way through pitch black darkness to their targets by correlating data on a map with radio transmitters installed at various locations throughout the UK, US, and Canada. Toward the end of the war, Gee and LORAN technology had developed to the point where pilots could fly straight to a target and bomb it without ever seeing it. The Gee devices installed in RAF fighter planes played a decisive role in Britain’s victory in the air war against the Nazis during World War II.

After the war, both systems were used for many decades to come. The Gee system stayed in use in British and other Commonwealth aircraft until 1970, when the last Gee transmitter was shut down. Updated versions of the LORAN were used worldwide for both aircraft and ships until the 1980s-1990s, when GPS technology began to replace it. The last American LORAN transmitters were turned off in 2010.

Another groundbreaking development from German scientists was the Sonne, or “Consol” (as it was known in the UK) system. The Sonne transmitters transmitted radio beams that shot across the night sky in any direction. The Sonne system was widely used by German planes and ships navigating through the darkness of occupied Europe at night….as well as by British forces hunting down those same Germans! After the war, the Sonne network was widely used around the world for maritime navigation until 1991, when the very first Sonne transmitter set up by the Nazis in Norway was retired.

One thing is for certain: After the dust from war had begun to settle, these radio navigation systems changed air and sea navigation as we knew it.

Radar

An H2X radar set installed in a plane, most likely an American B-17, during WWII.

One of the most important devices to debut during World War II was the radar. Portable radar sets such as the H2X set on the right gave Allied aircraft a huge advantage over German forces during the war. They also made flying at night much easier and made enemy targets in the air and on the ground much easier to detect when the night sky gave enemy planes natural cover. Ground radar was used to pinpoint night fighters in the sky and to help coordinate anti-aircraft guns.

Over seven decades on, radar is still a very important part of our world today and is used for detecting storms, aircraft, and much, much more 24 hours a day. A few of the giant Würzburg radar units used by German forces during the war was used by several European nations including the Netherlands, the USSR, and France for much more important purpose afterwards: For detecting quasars, black holes, and pulsars in the night sky. These radars opened the door for the modern day science of radio astronomy.

Pressurized Cabins
The World War II era was also the period when modern-day jet airliners were born. While the war raged around the globe, aircraft designers kept working on creating aircraft with pressurized cabins that could fly at higher altitudes than the aircraft of the time and eliminate the need for oxygen masks for bomber crews, etc. Experiments on pressurization began as far back as 1920 by countries such as the US, France, Germany, and the USSR. Prior to the outbreak of war in Europe, the Americans unveiled the first pressurized airliner to the world: the Boeing 307. Only 10 of these airliners saw service and from late 1941 onwards, all of the American aircraft industry’s attention was solely devoted to the war effort. Five of the 307s ended up being acquisitioned by the US Army and put to use as C-75 transport aircraft.

Thanks to its pressurized cabin, the Boeing 307 had the capability of soaring up to 20,000 feet. It had the capability of carrying 35 passengers and 5 crew members and it featured a 12-foot (3.6 meter) wide cabin specially designed to give night fliers a comfortable berth!

While all the developments in night flying during the World War II years happened on the military’s side, all this new technology would start to be put to full use by civilian airliners after the Allied victory in 1945. From 1945 onwards, the stage was set for the era of flying that would come next: the Jet Age. And it was during the early years of the Jet Age that red-eye flights as we know them were born.

For part three of this series (Night flying in the early years of the Jet Age), please click here.

Links:
http://timeandnavigation.si.edu/navigating-air/challenges/overcoming-challenges (Website from the Smithsonian Institution about overcoming the challenges of navigation at night and in stormy weather throughout the history of aviation. Features an online gallery of equipment used in aircraft from the early days of flight up to the 1990s.)
http://www.bbc.co.uk/history/topics/radar (A history of radar from the BBC.)
http://www.loran-history.info/ (An excellent website dedicated to the history of LORAN and the USCG crews who manned the LORAN stations.)
https://www.astron.nl/~leeuwen/video/dloo/JAHH9p3.pdf (The Beginnings of Radio Astronomy in the Netherlands)
http://www.narit.or.th/en/files/2007JAHHvol10/2007JAHH…10..221O.pdf  (Highlighting the History of French Radio Astronomy. 3: The Würzburg Antennas at Marcoussis, Meudon, and Nançay)
http://www.boeing.com/history/products/model-307-stratoliner.page

Bibliography:
-Johnson, Brian. The Secret War. London: BBC/Methuen Publishers, 1978. Chapters 1-2.
-Braude, S.Y., ‎Dubinskii, B.A., Kaidanovskii, N.L. A Brief History of Radio Astronomy in the USSR: A Collection of Scientific Essays. New York: Springer Publishing, 2012, pg. 11.
-Okumiya, Masatake, Horikoshi, Jiro, Caidin, Martin. Zero! New York: Ballatine Books, 1956, pg. 211.


Credits:
Boeing 307 picture: San Diego Air & Space Museum Archives. Used courtesy of Flickr’s The Commons.
“Bernhard” picture: Australian armed forces.
H2X radar: USAF/486 Bomber Group Association
*All pics used courtesy of Wikimedia Commons unless otherwise noted.

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