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DID YOU KNOW, December 2022

Updated: Aug 11, 2023

December 5th - Cohen & Hubbard and the Question: Will Pluto & Neptune Collide?

Did you know that Pluto and Neptune change places as far as which is farther from the Sun? Did you know that there is a link between this fact and Dahlgren?

Several months ago (on July 18th), we mentioned the extraordinary work that Dr. Paul Herget performed on the Naval Ordnance Research Calculator (NORC) in Dahlgren regarding the orbit of a minor planet named after it.

Eight years after Herget’s work, in 1964, mathematician Dr. Charles Cohen and physicist Elbert Hubbard spent 100 hours watching that same computer in Dahlgren perform five billion arithmetic operations to determine whether or not Pluto and Neptune would ever collide. This study required knowledge of equations of motion and observations of the planets made prior to 1950. The answer? After computing the positions of Neptune and Pluto every 40 days for the next 120,000 years, it was determined that there is practically no chance of that happening.

Images – Top Row: Neptune and Pluto (NASA photos); Bottom Row: the NORC computer and Dr. Charles Cohen (U.S. Navy Photos).

December 12th - Electromagnetic Railgun World Record & Why that Matters

On December 10, 2010, in Dahlgren, Virginia, the Navy set a new electromagnetic railgun world record with a 33-megajoule shot.

To put that power into perspective, that is the same as the kinetic energy of 33 Mitsubishi Mirages moving at 100 mph. Such records and experimentation do have a point behind record breaking itself, and in this case, the goal is to increase the distance between our military personnel and their targets. The difference between the electromagnetic railgun and what we traditionally think of as a gun is that it uses a current to accelerate a projectile rather than an explosion.

Image (Left): U.S. Navy Photo of railgun shot. (Right): Mitsubishi Mirage (Photographer: Thomas Doerfer, Mitsubishi Space Star, 14 September 2014. Found on License: )

December 19th - Dahlgren Wayside's Earlier Name: Hedrick Beach

Prior to the construction of the new Gov. Harry W. Nice Memorial/Sen. Thomas “Mac” Middleton Bridge, many enjoyed visiting an area commonly referred to as the Dahlgren Wayside. But did you know that, during the early 1940s, that area was actually called Hedrick Beach?

Captain David Hedrick was Commanding Officer at Dahlgren from April 1941 to June 1946. Dahlgren developed the computing reputation that it has today in part because he pushed for ever better calculating machines and the staff to run them.

Image: U.S. Navy Photo of Capt. Hedrick taken in 1941.

December 26th - Dahlgren's Role in WWII Battleship Production

Did you know that several groups were involved in producing battleships and that Dahlgren was a well-oiled part of an extensive machine that produced fully-stocked battleships for the United States during World War II?

Battleships were built at a number of US shipyards, including Philadelphia Navy Yard, New York Navy Yard, Newport News, and the Fore River shipyard. Main Battery guns were built by the Naval Gun Factory (at Washington Navy Yard), Bethlehem Steel Company, Midvale Steel Company, and at Watervliet Arsenal (US Army). Of the concerns listed, the Naval Gun Factory produced the largest numbers.

The heavy forgings that were used to build the guns at the Naval Gun Factory were typically supplied in a rough form from Bethlehem Steel or Midvale Steel and then finished, machined, and assembled at the Naval Gun Factory. After they were assembled, the bores machined, chambers machined, rifling cut and lapped, and breech mechanisms fitted, the guns were sent by barge to Dahlgren, where they were proof tested at Main Battery.

Once this was completed, the guns were sent back to the Naval Gun Factory for final inspection and for shipment to a shipyard or to storage. The typical timeline during WWII for proof firing of major-caliber guns at Dahlgren was that the gun arrived, was proof fired the next day, and left the following day.

Image: Gun barrel on a barge. (U.S. Navy Photo)

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