February 18, 2016

Celebrating African Americans in STEM: Lonnie Johnson, rocket scientist and inventor

by Bonnie Denmark

A prolific inventor with more than 100 patents, Lonnie G. Johnson is most famous for inventing the hugely popular Super Soaker®. However, Johnson’s accomplishments go far beyond the world of toys. He is also an aerospace engineer who helped develop the B-2 Stealth Bomber before working on the Galileo mission to Jupiter, the Mars Observer Project, and the Cassini mission to Saturn.

While trying to create an environmentally-friendly cooling device at home one night, Johnson serendipitously invented the world’s most powerful water gun. A New York Times article says, “Mr. Johnson did for water pistols what he had done earlier in his career for energizing space probes.” The Super Soaker, which has earned over $1 billion since its release, was inducted into the National Toy Hall of Fame in 2015 and is listed among the 100 most influential toys since the 1920s in TIME Magazine’s All-TIME 100 Greatest Toys.

Lonnie G. Johnson (1949-), rocket scientist and inventor. (Courtesy of Johnson Research & Affiliates)

In 1969, Johnson graduated in the last segregated class of his Mobile, Alabama, high school. Although he was advised not to aspire to be more than a technician, he was determined to become an inventor. Johnson had always been a tinkerer, building his own toys as a child and outfitting a homemade go-kart with a lawnmower engine as a young teen. In 1968, Johnson represented his high school at an engineering fair held at the University of Alabama, where he was the only black student competing. No one spoke to him during the competition, but he won first place for a robot he built from scraps – and powered by compressed air, just as the Super Soaker would be decades later. Johnson went on to earn a bachelor’s degree in mechanical engineering and a master’s degree in nuclear engineering from Tuskegee University.

After many career accomplishments as an engineer with the US Air Force and NASA’s Jet Propulsion Laboratory, Johnson founded his own companies that focus on green energy technology. One of his inventions, the Johnson Thermo-Electrochemical Converter System (JTEC), received a Popular Mechanics 2008 Breakthrough Award for “inventions that will change our world.” The JTEC converts heat directly into electricity and is based on the Carnot Cycle, proposed in 1824 by French Engineer Sadi Carnot and still touted in thermodynamics as the ideal cycle for converting heat to work. Carnot demonstrated that the efficiency of steam engines was a result of temperature differences, where heat flows from the hot parts to the cooler parts of an engine. (Read about Sadi Carnot’s work on energy transfer in our module Thermodynamics I.) But instead of using heat to move an engine as in the original Carnot Cycle, the JTEC uses temperature differences to force hydrogen ions through a membrane.

In a Carnot heat engine, heat QH flows from a high temperature TH furnace through a working substance, and the remaining heat QC flows into the cold sink TC, forcing the working substance to do mechanical work W via cycles of contractions and expansions. Johnson’s JTEC is based on the same principle but has no moving parts. (Wikimedia Commons)

With research supported by the US Department of Defense, one of Johnson’s companies, Excellatron, aims to improve batteries for electric vehicles so they might go 1,000 miles on a single charge, a great leap from the current state of electric vehicles (Tesla has an $85,000 electric car that boasts 270 miles per charge, but vehicles within reach of the middle class generally cannot reach 100 miles on one battery charge). According to an Excellatron press release, Johnson’s sole mission now is “to ensure the world has enough energy for a prosperous future.”

Johnson has received numerous honors including an honorary doctorate from Tuskegee University, two Air Force Commendation Medals, an Air Force Achievement Medal, and multiple NASA awards. In 2011, he became the first African American to be inducted into the State of Alabama Engineering Hall of Fame. Not bad for a kid who was told not to dream of becoming more than a technician.



See Lonnie Johnson explain the science behind his JTEC thermodynamic energy converter at the Palo Alto Research Center (PARC) Forum, High efficiency solid state engine (video), 2009.

For more information, read the Lonnie G. Johnson Biography at A&E’s Biography.com.

Read our profile of another inspiring African American scientist, Percy Lavon Julian: Revolutionizing medical treatment through chemical synthesis.

Written by

Bonnie Denmark holds an MA in linguistics and teacher certification in English, ESL, and Spanish. She has devoted her professional life to educational and accessibility issues as a computational linguist, multimedia curriculum developer, educator, and writer. She has also worked nationally and internationally as a language instructor, educational technology consultant, and teacher trainer. Bonnie joined the Visionlearning team as a literacy specialist in 2011, assisting the project by developing comprehension aids for science modules and creating other STEM learning materials.

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