Future Rear Admiral Albert G. Mumma took over the propeller desk at the David Taylor Model Basin in the early 1940s. Captain Hyman Rickover was an opposite number in the technical section working everything electrical. Mumma had graduated from the U.S. Naval Academy and had several surface tours before completing graduate studies in the United States and France and moving on and up in naval engineering and construction.
In late 1944, Mumma joined the top-secret Manhattan Project’s Alsos Mission investigating German progress on the atomic bomb. He traveled through Germany while the war was still on, helping to corral German scientists, including Dr. Hellmuth Walter and his group working on a new generation of U-boats and the V-1 and V-2 rockets.
At war’s end, Mumma headed machinery design at the Bureau of Ships. “I don’t think it’s generally known,” he recalled in his Naval Institute oral history, “but the Naval Research Laboratory had been working on a nuclear power project from the very beginning of the war.” Work had been stopped by the Manhattan Project’s edict that concentration be solely on the atomic bomb.
Mumma met with the project’s leader, Lieutenant General Leslie Groves Jr., soon after the war, but he was unable to secure any fissionable material for planned Navy reactor development. He and his team decided to push ahead with the reactor anyway, working on everything but the fuel core. Mumma was dismayed when Rickover was selected to go to Oak Ridge to lead the project.
Mumma’s earlier work on propellers, however, would put him on track for flag rank. Hundreds of new ships of different classes were being built at the outset of the war, with new designs—and accompanying technical flaws.
We had identified several problems with propellers, not only vibration problems but also a singing propeller problem, which was relatively unknown at that time.
We found out that by pinging on propellers in air that they would sing, they would vibrate. Then the frequency would change due to the mass of the entrained water, along with the mass of the blades. We experimentally were able to produce a singing propeller.
We soon found out that we had singing propellers on our submarines. They were making noise. Everyone used to say it was squealing shafts, but it was singing propellers, and the blades were vibrating. This was caused by sloppy work on the finish of the propellers, not according to the design, where the edges were made a little too blunt and it would throw a vortex.
An example of that singing involved Captain Robert B. Carney, the first commander of the new light cruiser USS Denver (CL-58) in October 1942.
I was called up to Philadelphia Navy Yard because they had a problem. They said they had shaft squeal that would take anywhere from four to six weeks to repair.
I had taken some instruments up with me to measure frequency. I said to Captain Carney, “Captain, if you’ll take the ship down Delaware Bay a little way, and maybe out into the ocean depending on what speeds we have to make, I would like to control the speed from the engine room, cover the range of speeds of the shafts through but not up to full power.” He said okay.
We got about halfway down Delaware Bay when I learned she had singing propellers. I went up and told the captain “We don’t have to take her any higher. We can turn around and go back to the yard. What we’ll do is take your propellers off. We’ll work on them overnight.”
He said, “My God, Mumma. You mean to tell me you’re not going to take four to six weeks.” I said, “No, sir.”
I stayed with the job and made sure the propellers were satisfactory when they went back on the ship. Went to sea with him the following day—quiet as a church. Well, he was overjoyed, and he went to sea happy to fight the wars. It may not have been by accident that when he was Chief of Naval Operations I was made Chief of the Bureau of Ships. I don’t know.
