In our exhibition Time and Navigation visitors can set their watches by a working cesium frequency standard, commonly known as an “atomic clock,” on loan from the National Museum of American History. The exhibit allows visitors to see different methods of measuring time, including mechanical and electrical clocks. A digital display on the atomic clock shows the global reference known as the Coordinated Universal Time or UTC. A separate display connected to the clock shows local time, which visitors can use to set their watches. While the device is not connected to outside time sources, it will keep accurate time within a tiny fraction of a second over the foreseeable future. We jokingly called it our “Box of Time.”
What is an Atomic Clock?
Atomic clocks maintain very stable time references at specialized laboratories such as the U.S. Naval Observatory and the National Institute of Standards and Technology. The time is distributed all over the world by satellites, radio signals, fiber optic connections, and computer networks. These time standards are essential for synchronizing data connections, communications, transportation, and countless other aspects of modern society.
Atomic “clocks” can be more precisely called frequency standards. They maintain stable frequencies by measuring changes in the energy state of heavy elements such as cesium. These devices know exactly the length of each second with a precision of a billionth of a second. The unit sends out pulses exactly one second apart. By itself, the frequency standard doesn’t actually know the time of day. Keeping track of that requires a second piece of equipment: A time code generator. This device takes the pulses from the frequency standard to keep track of hours, minutes, and seconds. (Jump to minute 17:30 of this STEM in 30 episode to see the U.S. Naval Observatory and learn more about how an atomic clock works.)
Setting Up the Clock in the Museum
Our atomic clock was the last thing to be installed in our exhibition in 2014. Before it could be installed, we needed the frequency standard to be calibrated because each atomic clock can run at a slightly different rate. To determine how ours was working, we wanted to compare its operation to the national reference time. Fortunately for us, this originates right in Washington, DC at the U.S. Naval Observatory. The staff there agreed to let us bring our clock in for calibration. It was a tricky procedure. We had to calibrate both the frequency standard and the time code generator and then bring them back to the Museum. During all this, electrical power to the clock had to be maintained. We brought along a battery power unit used for computers. Along with the internal battery backup in the frequency standard, we hoped this would give us about 90 minutes of power. To be safe, we planned to plug in the whole system to the vehicle’s power supply.
With a plan in place, we picked up the clock from the National Museum of American History, along with its curator Roger Sherman. The unit had a helpful note on top that said, “Roger’s Atomic Clock.” The battery backup worked flawlessly as we made our way up Massachusetts Avenue to the Naval Observatory.
Once at the Observatory’s time service building, we plugged in the necessary cables to compare our clock with the U.S. master clock. The initial comparison showed that our clock was running about 24 nanoseconds (billionths of a second) slow. After a couple hours, this offset had changed to less than a nanosecond. This told us the frequency standard was running well. Over the next 10 years it will drift out of sync with the national time reference by only less than 1/10,000th of a second. That sounded good enough for museum visitors to set their watches. While there we also set the time of day on the time code generator.
We packed up the frequency standard, the time code generator, the battery backup, and began the drive back to the Museum. I was behind the wheel with the power supply plugged into the dashboard. Roger was in the back seat with the equipment. At one point, driving down Independence Avenue, something began to emit ear-splitting cries. Roger and I tried to determine which piece of equipment was complaining. It turned out to be the overloaded power supply. I pulled the plug out of the dashboard port, which was so hot it almost burned my fingers. Then the UPS on the floor started beeping loudly because it wasn’t getting power. Everything was confusion in the vehicle as we shouted above the noisy equipment while checking all the units and cables. But after that brief moment of excitement, we had enough juice in the battery backup to make it the rest of the way to the Museum. After some careful coordination with all the cables, we got it mounted in its display case where it continues to display the time.
This wouldn’t be the last time we needed to adjust our atomic clock. In June 2015 we had to account for a leap second. In my next post I’ll explain what a leap second is and how we updated our atomic clock.
A special thanks to everyone at the U.S. Naval Observatory, the people at Symetricomm (now Microsemi) who manufactured the clock, and Roger Sherman at the National Museum of American History.
Andrew Johnston was a research associate in our Center for Earth and Planetary Studies. He is now the Vice President of Astronomy & Collections at the Adler Planetarium in Chicago.
Last October, we announced that we had acquired the collection of Sally K. Ride, the first American woman in space. Now, we can share that the archival portion of the collection has been processed and is available for research! See our finding aid for more detailed information.
The Sally K. Ride collection consists of more than 23 cubic feet of papers, photographs, certificates, and film created or collected by Ride chronicling her career from the 1970s through the 2010s. The papers document Ride’s lifetime of professional achievements and include material relating to her astronaut training and duties; her contributions to space policy; her work as a physicist; and her work as an educator.
A significant portion of the collection highlights her iconic role as a NASA astronaut from 1978 to 1987. Ride spent 343 hours in space, as a mission specialist on space shuttle missions STS-7 and STS-41G, where she operated a variety of orbiter systems and experiment payloads. She also operated the Remote Manipulator System (RMS) arm to maneuver, release, and retrieve a free-flying satellite.
But Ride’s NASA’s career and legacy extend well beyond her missions in space. Ride was training for her third flight when the Space Shuttle Challenger disaster occurred and she was named to the Rogers Commission, the presidential commission investigating the accident. Ride later served on the Columbia Accident Board as well. She was the only person assigned to both shuttle disaster committees that investigated the causes and recommended remedies after the tragic losses.
In 1987, Ride left NASA to become a full-time educator. The collection mirrors those professional changes with material relating to her work as a physics professor at University of California at San Diego (UCSD) and later endeavors to improve science education for elementary and middle school students, with a special focus on science education for girls.
The Museum is proud to play a role in securing Ride’s legacy by making this collection available to researchers for years to come. And, on a personal note, it was a wonderful honor to process the papers. I leave you with my favorite image from the collection. It shows a very young Sally Ride looking at a book. A “thought bubble” caption has been adhered to the photo as though Ride is reading a technical manual. I found this image attached on the inside cover of one of her STS-7 manuals.
Patti Williams is the acquisition archivist for the National Air and Space Museum
If you were going to fly non-stop for 33½ hours, what kind of chair would you want to sit in?
For Charles Lindbergh, it was this simple wicker chair. The Ryan NYP Spirit of St. Louis was a modified version of the Ryan M-2 aircraft created specifically for the long flight from New York to Paris. In an effort to save weight, Lindbergh opted for this wicker seat for the historic flight. Discover more about the Ryan NYP Sprit of St. Louis.
Tom Paone is a Museum Technician in the Aeronautics Department at the National Air and Space Museum.
Who would think that a damaged, old leather glove, with the thumb badly torn, could be a valuable item? But if that damaged glove belonged to Luftwaffe pilot Günther Rall, with 275 aerial victories and the third highest scoring ace in aviation history, then it becomes an item of unique historic value. And now that item has found a home at the National Air and Space Museum. In addition to the glove, the Museum also received Rall’s diary from 1942, documenting his actions at the Eastern Front, and a portrait of the pilot in summer 1945, created by another prisoner of war, Wolfgang Willrich, during their time in captivity in Fouquainville, France.
Günther Rall was born in 1918 at the end of World War I and became a pilot with the Luftwaffe in 1938. During World War II, he fought in the skies over France, Great Britain, Yugoslavia, Greece, Russia, and later in the air defense over Germany against the American and British strategic bombardment campaign—always flying the Messerschmitt Bf 109. In November 1941, after 37 air victories, Rall was shot down for the first time and rescued by a German tank crew, his back broken in three places. Told that he would never be able to walk (let alone fly) again, Rall returned to combat just one year later.
In April 1944, Major Günther Rall was made Group Commander of the 2nd group of Fighter Wing 11, defending the skies over Germany against the overwhelming powers of the Allied Air Forces. At that time, the Allies had seven to 10 times more aircraft in the air over Germany than Germany did. Even worse, U.S. pilots had about 400 flight hours of training when they were sent into battle, while German pilots, due to lack of instructors and fuel, had almost none. Many of these young, inexperienced German pilots were shot down before their 10th sortie.
On May 12, 1944, Rall led his group against an American air raid. His pilots flew two different aircraft. Some flew Me 109s with engines equipped with special chargers to allow them to reach altitudes of 8,000 to 10,000 meters where they were able to attack the P-51 Mustang and P-47 Thunderbolts that protected Allied bomber units. Other pilots flew Fw 190s and attacked the lower-flying U.S. bomber aircraft. Rall shot down two Thunderbolts, but then other P-47s arrived. One of them fired at Rall’s Me 109. Bullets from a .50 caliber machine gun hit his cockpit, his engine, his cooler, and his left hand at the control stick, shooting his thumb. The glove donated to the Museum is the very glove worn by Rall during that engagement, and it clearly shows the damage from the machine gun round. Günther Rall bailed out and landed in a field. He was taken to a hospital and his left thumb amputated. Due to the onset of infections he was not able to fly for months.
The air battles of that day marked the beginning of a systematic U.S. offensive against the German fuel industry, one of the weakest links in the German war economy. The 8th and 9th USAAF with 886 bombers, and 980 accompanying fighters, flew attacks against refineries and production sites for synthetic fuel in the heart of Germany. Facing heavy German resistance, the U.S. lost 46 bombers and 12 fighters. On the German side, 28 pilots were killed and 26 wounded that day, among them was the entirety of Rall’s group. Later, Albert Speer, Reich Minister of Armament and War Production, would declare: “On that day, the fate of Germany’s technical warfare was decided.”
In November 1944, Rall returned to active duty. He spent the last months of the war with Fighter Wing 300, which mostly sat idly due to lack of fuel and supplies. At the end of the war, after 621 missions flown, 275 confirmed aerial victories, shot down eight times, and wounded three, Rall became a prisoner of war of the American Forces. Released in August 1945, he had to adjust to a civilian life and became a representative for the Siemens Company. In 1956, he joined the newly established Armed Forces of the Federal Republic in the rank of a Major of the Luftwaffe. He was put in charge of modifying the F-104 fighter jet for Luftwaffe’s requirements and worked his way to the position of Luftwaffe’s Inspector General, a rank he held from 1971 to 1974. That year, he was made the German military representative in NATO’s Military Committee at Brussels, with the rank of a Lieutenant General.
In 1977, Günther Rall visited a meeting of U.S. fighter pilots. While inquiring about the 1944 incident where he lost his thumb, he learned that he had encountered the notorious “Wolf Pack” on that fateful day in 1944, the 56th Fighter Group under Col. Hubert Hub Zemke. Zemke’s pilots were by far the most successful American fighter group in the European theatre, and Zemke himself was known as a supreme tactician. From that meeting, a close friendship developed between Rall, Hub Zemke, Zemke’s 2nd Lieutenant Robert “Shortie” Rankin, and other U.S. pilots. During his visits to the U.S., Rall frequently gave talks about his life as a pilot, often together with U.S. pilots like Hub Zemke or Chuck Yeager. In May 1996, he joined the Gathering of Eagles at the Museum and talked about his war time experiences. In 2003, he was made an honorary member of the prestigious Society of Experimental Test Pilots, and one year later published his memoirs, Mein Flugbuch [edited by Kurt Braatz, Moosburg/Germany: Edition NeunundzwanzigSechs]. In them, the third-highest scoring ace of all time said:
“Nothing is further from my mind than to join into the praise for the last Knights of the Air which you hear so often when people talk about World War II fighter pilots. The sober truth […] is that we fought each other for life and death, although we wanted nothing but to live, and that these fights became the more relentless the longer this terrible war lasted. […] War is not the continuation of politics with other means, but an infamy; it is the utter failure of political action.”
Günther Rall died in 2009. The Museum plans to incorporate his glove, his diary, and his portrait in a new exhibition on World War II.
Evelyn Crellin is the curator for European Aviation in the Museum’s Aeronautics Department
As the curator for the Museum’s Martin B-26B Marauder, I’ve become obsessed with the proper way to designate the name given to it by its first pilot Jim Farrell in August 1943. It all centers on the pesky use of a hyphen. Is it Flak Bait or Flak-Bait? You see both in archival documents, historical references and books, and all over the internet. Which one is correct? In my quest to get that one detail right, I learned that the use of the term “flak bait” referred to more than just the name of the World War II, medium bomber that is now undergoing preservation treatment in the Mary Baker Engen Restoration Hangar at the Steven F. Udvar-Hazy Center.
American aircrew that were going into combat would describe themselves as “flak bait,” meaning they were at the mercy of enemy anti-aircraft artillery. “Flak,” which was short for the German fliegerabwehrkanone, or literally “flyer defense cannon,” was the primary threat to bomber crews over their targets. U.S. Army Air Forces Ninth Air Force medium bomber crews, specifically those flying the B-26 Marauder, adopted that name collectively for themselves as they risked their lives over Nazi-occupied Europe.
At least three other American aircraft went into battle over Europe with the name Flak Bait in World War II. A Douglas C-47 Dakota in the 437th Troop Carrier Group of the Ninth was one. Lt. Bill Barlow of the 353rd Fighter Group in the Eighth Air Force named his Republic P-47D Thunderbolt Flak Bait because it always came back from a mission with a few holes somewhere on the airframe. I also found one mention of an Eighth Air Force Boeing B-17 Flying Fortress that carried the name.
Does anyone have a personal connection with these aircraft, have any more details, or know of any other World War II aircraft that flew with the name Flak Bait?
How did the Museum’s B-26 get its name? Pilot Jim Farrell took inspiration from the nickname his brother gave to Boots the family dog back home, “Flea Bait,” and adapted it to reflect the combat environment over Western Europe.
With the approval of the crew, Farrell took those two words and sketched them popping out of a flak burst. Squadron artist Ted Simonaitis painted the now iconic nose art in yellow, red, and white on the left forward fuselage. See the narrow hyphen between “Flak” and “Bait?” While combat crews rightly called themselves “flak bait” and there were other aircraft that carried the name, there is only one Flak-Bait, the airplane that flew more missions than any other American aircraft during World War II.
Jeremy Kinney is a curator in the Aeronautics Department at the National Air and Space Museum.