Radar!

Popular Science ad Oct 1945

I've been thinking how to introduce a very important aspect of the L8 mystery.

Radar.

Everyone is familiar with it. We all understand it's used to detect remote objects, bouncing an electronic signal off an object, the reflection showing up  form and distance of the object in a scope of some sort.

That's just scratching the surface though. It was used for so much more.

Radar has been claimed as the invention of many people and many groups. I won't dispute any claims, but I will suggest that there is a difference between theoretical work and the invention and ingenuity. There are many great sources on the history of radar available in  books and on-line articles. Names like Watson-Wyatt and Lord Beaverbrook will be part of the common histories. I'll leave the credit and timeline of events for the creation of radar to historians to argue over.

More important to the story of the L-8 are related to the evolution of radar into weapons of war.
 The story surrounding the fate of the L8  crew involves radar I believe. More proof later but first an introduction into radar and some of the problems early units had.

Among the names you may recognize -but probably not -  is Sir Henry Tizzard. You may want to Google or Wikipedia "Tizzard Mission". As with all parts of the story, there's a public view  made up of smoke and mirrors to cover the back-story.


The war is raging in Europe and Britain is teetering on the brink of falling. They need American help if they are to stay alive.The Tizzard Mission was created by the Brits to try and  negotiate an exchange of technology, weapons and supplies. In exchange they offered the Americans the best technology advancement they had... the 3 cm. Magnetron!

For those who may not understand the role of the magnetron and how radar works I'll attempt to give a short and hopefully lucid explanation for those who might not understand how it works and the range of its uses. The basic concept is that by producing high-frequency electromagnetic energy in the microwave range you can use that energy to do things like detect objects at great distances, navigation, or identification.
One of the point of contention I come across with the story of who developed radar is who first noticed the phenomena that electronic equipment was effected by signals bouncing off nearby ships. Scieitists from many nations make claim that they noticed the effect on some such piece of equiptment when a ship or airplane reflected back an energy beam. Like yelling in a canyon  prodcues an echo, or thunder claps, one can measure distance by timing the sound that returns after bouncing off the canyon wall. If we have a louder signal like a whistle we can measure distance to farther objects reflecting the sound.  I won't suggest any prize-winners here as it doesn't really matter.

What I will say is that at the heart of radar hardware is the device that generates the microwave energy that we bounce and time. That device is a magnetron. As a whistle is to sound, a magnetron is to microwaves.
The energy is used to paint a picture by "illuminating" a picture of reflected energy.
Many electronic devices for generating microwaves existed but they had the shortcoming of producing a frequency of 10cm. This impacts the granularity of the image. Think of the old days of dot-matrix pictures and the images you could print versus modern printers with fine granularity of pixels. The width of the energy that could bounce off a large object was too wide to be effective in painting a small object with energy. A wide brush that is fine for painting a Mark Rothko painting would be useless in painting a Manet painting. The "brush" determines the level of detail possible and so it is with the wavelength of the microwaves produced by the magnetron.

This makes early warning systems possible. Targeting systems. Other uses for that energy would also be used for navigation. If you have a receiver that can detect synchronized signals from three known locations and utilizing timing to determine distance you can locate your position on the planet.

A coded signal containing data could identify "friends and foes" in a sky full of aircraft buzzing about.
This and much more were now possible.

What we can say is that the British were responsible for the revolutionary 3 centimeter magnetron.
The fine brush needed to detect and draw aircraft sized objects, but they needed help in turning into a weapon of war before it was too late.

A car pulled up to the AT&T building on Broadway in lower Manhattan, New York City, June of 1940, and a group of men got out and the world would never be the same again. In that car was Sir Henry Tizzard and his entourage. They carried one of the most tightly guarded secrets with them - a 3 cm magnetron.


The group of men discussed setting up an exchange of information, the Norden bomb sight, hoping to trade their secret for our best invention and supplies. The bomb sight was the latest and greatest technology and the British thought this was the key to salvation. I don't think that anyone realized that salvation started with this meeting. The supplies they were after - food and critical goods - would allow them to survive and fight another day.

The result of those initial meetings was to create a group of scientists from Britain and America working in partnership.

Radar was developed by the NDRC, later known as the OSRD, or Office of Scientific Research and Development. MIT's Rad Lab in Boston was the center of that activity. Karl Compton was the head of Division 14 that dealt with radar development. Interesting tid-bit. Donald Trump's uncle John was the secretary ( what would now be called a Chief of Staff ). He must have been  a remarkable person since his job would have been like herding a group of cats - and the cats all have an I.Q. of 175!

Radar components were built throughout the US. The magnetron that the British brought with them was first manufactured at Bell labs in Whippany, NJ. The circuits and cabinets were built in Newark at the old Westinghouse building. The building was torn down a few years back and now sits next to the Broad St train station in Newark, a pile of rubble. Radar sets were tested at Atlantic Highlands New Jersey. A house was rented there and the scientists tested using the nearby Staten Island Ferry which moved on a predictable schedule between Staten Island New York and lower Manhattan. The Staten Island Ferry was the first "enemy" target of the new improved radar. Philco in Pittsburgh, PA was the primary vendor for the OSRD contract and became the final assembly point once radar started regular manufacture. The first units that went into blimps starting in 1941 weighed about 250 pounds but by 1942 weighted about 150 pounds. About the  weight of one man...

The units were hand made and problematic. On-off switches when on, but failed to turn off. The Transmit-Receive Tube responsible for energy transmission leaked through cracks in the mica windows. The TR tubes ( conduit really ) were rigid and gaps formed when the blimps were thrown to and fro during the regular flights.

Division 15 dealt with the Radar countermeasures. Jamming and tracking radar sources. They met around the corner at West St. The building still exists and is next to the new World Trade Center building one. For those who might visit New York the building is located at the PATH station at the base of the building. The old AT&T building is a right out of the entrance and one block over to Broadway next to the church.
The first informal meeting of Division 15 happened to be on December 7, 1941!

An interesting bit of trivia from Division 15 dealt with the design of the first radar jamming antenna. It went on ships since the equipment to produce the power was bigger than could be handled by blimps and saving ships was such a high priority.  The head of NBC was a member and when the group started discussing the most likely design for the antenna they all thought would work best,  he mentioned that NBC had just the right antenna. The men of Division 15 scrambled down to West St and loaded into two cars, driving uptown to the Empire State Building. The antenna mentioned was at the top of the Empire State Building transmitting radio for NBC. A copy of this became  the first antenna used on ships to jam radar.

We're not done with this part of the story just yet... more than science came with the Tizzard Mission...

                    Otto

                       otto@ghostblimp.com