David was born on his father's birthday - the oldest of four children born to Halroyd and Helen Simmons. David passed away peacefully at the age of 82 (990 months). David is survived by his sister, Halli Sue (Simmons) and Jack Lee Tills, of Oxford, OH; his brother, Evan Simmons and Leslie Ferriel, of Vashon Island, WA; and his sister, Ann (Simmons) and Nick Black of Wolfeboro, NH. David found great joy in taking and sharing family photos throughout his life. Though David had no children of his own, he was an incredible uncle to his many nieces and nephews (Lara and Gary Haines, Matthew and Laura Tills, Justin and Kari Marbury, Aaron and Samantha Marbury, Phillip and Erica Marbury, Reed and Megan Marbury, and Nicholas and Gillian Simmons), his many great nieces and nephews, and one great-great nephew. David had a special heart for children.

David graduated valedictorian from Hayden High School in Hayden, Arizona in 1960. He studied Physics at the University of Arizona where he roomed with his best friend, Don Finch. He went on to get a degree from the University of Utah and a PhD in Physics from the University of Virginia. He had a long career working as a Nuclear Physicist and finished his career at Los Alamos National Laboratory in New Mexico.

David loved all things outdoors—from scouting events growing up and family backpacking trips in New Mexico to epic rafting trips down the Salmon River in Idaho.  He loved to create and invent, and spent much of his time working with his hands creating anything from "perfect solid" models to wow his nieces and nephews to specialized and custom storage solutions from PVC pipe. David was an avid reader and collector of books. As someone with a lifelong love of learning and science, David chose to donate his body to help medical students at the University of Cincinnati.