Kay, 96, died on October 29 and was buried with full military honors.
A highly decorated navigator who led some of the most dangerous bombing raids against Germany during World War II, Kay was also credited with launching the concept of the A-10 Thunderbolt, better known as the Warthog.
Despite lacking the air-to-air combat ability of the F-15 Eagle and the high-tech stealth capabilities of the F-22 Raptor, the U.S. Air Force still uses the A-10 to support ground forces in close combat more than 40 years after its first flight in 1975.
But if it hadn't been for Kay, this iconic plane may have been grounded before ever seeing battle.
As an adviser to then-Air Force Chief of Staff John McConnell in the 1960s, Kay put his professional reputation on the line and led the fight to create a plane specifically designed to assist troops on the ground.
"Without Col. Kay, there would be no A-10 today," said Pierre Sprey, a former Pentagon official who helped Kay design the plane despite objections from many in the Air Force leadership.
At the time, the issue of close air support was at the center of a contentious budget debate between the Army and the Air Force over how to divide funding for fixed-wing planes and helicopters.
Army leaders often argued it took too long for the Air Force to respond to calls for assistance, specifically during the Vietnam War, and demanded control of budget funds to develop their own heavily armed helicopter that could better meet their needs.
The Air Force, however, wanted control over the development of all fixed-wing aircraft and insisted that any type of plane could perform close air support.
But in reality, the Air Force's top generals had little interest in dedicating budget dollars for improving support for ground troops, as they preferred planes that could carry out bombing missions deep in enemy territory.
Spearheading negotiations between the two service branches, Kay proposed an agreement under which the Army would relinquish control of the development of all fixed-wing aircraft as long as the Air Force fulfilled its promise to build a plane that was able to provide the air support that was lacking during Vietnam.
Using the very real threat of the Army's plan to build a helicopter to take over Air Force close support, Kay convinced McConnell that if the Army got its funding approved, he would go down in Air Force history as the chief that lost the close support mission and the money that goes along with it.
To counter the Army's proposal, Kay pitched a plan to build an airplane dedicated to the close support missions that would be cheaper and more effective than any helicopter.
McConnell approved the plan, but Kay quickly realized that he would have to circumvent the normal chain of command to fulfill his promise to the Army, as many of the Air Force's top generals still lacked interest in spending budget dollars on this cause.
Rather than approaching the Air Staff and Tactical command offices, which normally facilitate the building of new planes, Kay reached out to Sprey, who was working for the defense secretary, to help make his plan for the A-10 become a reality.
"What he did at this point is he put his career on the line," Sprey recalled.
Together, Kay and Sprey worked in secret to develop an aircraft that could cover ground troops from an enemy advance, buying time for grunts to regroup or get out with an aerial weapons strike.
"The entire A-10 community is basically due to his guts and his integrity," said Sprey, now an adviser for the Project on Government Oversight. "If anyone deserves the title of 'father of the A-10,' Col. Kay definitely does."
The A-10 has saved the lives of countless troops during each of the last four wars fought by the United States and is used today in the fight against ISIS in Iraq and Syria.
But today, the war bird is fighting a similar funding battle to the one Kay faced in the 1960s, surviving year to year because of the strain on Air Force funds resulting from budget sequestration.
Pentagon leadership thinks the A-10 is too expensive to maintain under the current spending limits when other aircraft can fill similar roles. And several lawmakers involved with military allocations believe other expensive undertakings -- such as finding ways to neutralize the deadly improvised explosive devices U.S. soldiers face in the Middle East -- are higher funding priorities.
Looming over the debate is the sleek, super-high-tech, massively expensive F-35 Lightning, which was expected to replace the A-10 as the Air Force's primary close air support aircraft. Despite its potential, the F-35 has been riddled with setbacks and is still a long way from deployment.
In January, Gen. David Goldfein, the Air Force's vice chief of staff, told Defense News the rise of ISIS and the U.S. air campaign to fight the terror group has prompted the service to reconsider plans to retire the A-10.
"When we made the decision on retiring the A-10, we made those decisions prior to ISIL, we were not in Iraq, we were coming out of Afghanistan to a large extent, we didn't have a resurgent Russia," Goldfein said in an interview on "Defense News With Vago Muradian."
Goldfein's office confirmed the general's remarks to CNN.
The retirement of the A-10 was not part of the Pentagon budget request submitted to Congress in February, but the plane's long-term future remains in question.