Comment by areoform
6 months ago
I'm quoting their research summary. By reverse engineering, it means that they figured out why the magnetron worked and then optimized it. They X-Rayed it, found a deviation from plans, then developed a model to understand why there was a deviation in performance.
However examples No. 11 and 12 had the number of resonators increased to 8 in order to maximise the efficiency of the valve with the magnetic field provided by the then available permanent magnet, E1189 also incorporated cooling fins to enable the device to be air rather than water cooled.
Sample No.12 was taken to the USA by E. Bowen with the Tizard mission and upon testing at Bell Labs produced 10 times the power at 5 times the frequency of the best performing American triodes. A certain amount of confusion arose as the drawings taken by Bowen still showed the 6 resonator anode but an X-Ray picture taken at Bell Labs revealed the presence of 8 resonators.
The E1189 or its Navy equivalent NT98 was used in the Naval radar type 271 which was the Allies first operational centimetric radar. The early RCM’s like the E1189 were prone to mode jumping (frequency instability) under pulse conditions and the problem was solved in by means of strapping together alternate segments a process invented by Sayers in 1942. Strapping also considerably increased the magnetron’s efficiency.
via, https://www.armms.org/media/uploads/06_armms_nov12_rburman.p...
and another account, https://westviewnews.org/2013/08/01/bell-labs-the-war-years/...
>the problem was solved in by means of strapping together alternate segments a process invented by Sayers in 1942
UK physicist James Sayers was part of the original team that developed the magnetron in the UK. He did join the Manhattan Project in 1943, so perhaps before that he came over to the US (to Bell Labs) as part of the radar effort: in that case strengthening Bell Labs contributions, weakening any claim to reverse engineering :) When Lee de Forest "invented" the triode tube amplifier, he had no idea how it worked. When Shockley "invented" the transistor, his team grumbled that he had stolen their work (similar to Steve Jobs, the boss, taking over the Macintosh project when his own Lisa project failed) but in any case, it was not actually understood yet how transistors worked. "How the First Transistor Worked: Even its inventors didn’t fully understand the point-contact transistor" https://spectrum.ieee.org/transistor-history
In these cases, the bleeding edge of R and the bleeding edge of D were the same thing. A certain amount of "reverse engineering" would have been mandatory, but it's really "reverse sciencing", "why did my experiment turn out so well", rather than "reverse engineering a competitor's product to understand how did they make it work so well."
https://en.wikipedia.org/wiki/MIT_Radiation_Laboratory
In early 1940, Winston Churchill organized what became the Tizard Mission to introduce U.S. researchers to several new technologies the UK had been developing. Among these was the cavity magnetron, a leap forward in the creation of microwaves that made them practical for use in aircraft for the first time. GEC made 12 prototype cavity magnetrons at Wembley in August 1940, and No 12 was sent to America with Bowen via the Tizard Mission, where it was shown on 19 September 1940 in Alfred Loomis’ apartment. The American NDRC Microwave Committee was stunned at the power level produced. However Bell Labs director Mervin Kelly was upset when it was X-rayed and had eight holes rather than the six holes shown on the GEC plans. After contacting (via the transatlantic cable) Dr Eric Megaw, GEC’s vacuum tube expert, Megaw recalled that when he had asked for 12 prototypes he said make 10 with 6 holes, one with 7 and one with 8; and there was no time to amend the drawings. No 12 with 8 holes was chosen for the Tizard Mission. So Bell Labs chose to copy the sample; and while early British magnetrons had six cavities American ones had eight cavities... By 1943 the [Rad Lab] began to deliver a stream of ever-improved devices, which could be produced in huge numbers by the U.S.'s industrial base. At its peak, the Rad Lab employed 4,000 at MIT and several other labs around the world, and designed half of all the radar systems used during the war.
that seems to be the source of the reverse engineering idea, and I think Bell Labs' role (which is quite important) was more toward perfecting the devices for manufacture at scale, as it was an arm of a giant leading edge industrial company.
I'm not diminishing Bell Labs nor anybody there, it was a lot of smart people.
> as part of the radar effort
Something I've been curious about and thought I'd ask the room here since it was mentioned.
It seems to me that "the radar effort" was very significant, almost Manhattan Project levels itself. In every book about scientists in WW2 or the atomic bomb that I've read, it seemed everyone had a friend "working on radar" or various scientist weren't available to work on the bomb because they were, again, "working on radar."
Was this true or just something I'm overanalyzing?
It's very true.
Guess who pioneered the venerable Silicon Valley, it's HP (then Agilent, now Keysight). Their first killer product was the function (signal/waveform) generator. HP basically the Levi's of the radar era, making tools for the radar/transistor/circuit technology gold rush.
One of the best academic engineering research labs in the world for many decades now is MIT Lincoln Lab, and guess what it's a radar research lab [1].
I can go on but you probably get the idea now.
[1] MIT Lincoln Laboratory:
https://www.ll.mit.edu/
3 replies →
Thank you so much for this detailed dive! I appreciate it!
Is there a particular primary source that you recommend?