What started as a roar turned into a rumble and then a buzz as two radial engines propelled a C-47 Skytrain down the runway at Centennial Airport and into the clear, cloudless Colorado sky on Friday morning.

The C-47 named “That’s All, Brother” is unique among the 10,000 such transport planes — it was the lead airplane of more than 800 that dropped some 13,000 paratroopers into the hornet’s nest that was Normandy, France, on June 6, 1944.

Many of the paratroopers were in their early 20s. Roughly 2,500 became casualties, either killed, wounded or missing in action. Forty-two C-47s were lost.

Christened by its pilot, Lt. Col John Donalson, the name was a message to Adolf Hitler — responsible for the murder and mayhem that engulfed Europe and other parts of the world — to inform him that his days terrorizing people were coming to a close.

Paratroopers in 1944 boarded the plane with parachutes, weaponry, and food. They were so weighed down with gear that they needed assistance to stand and board the airplane.

On Friday, the group that boarded the airplane were dressed in jeans, some in a polo shirt. The heaviest thing in people’s backpacks may have been a camera or laptop.

The loud buzzing of the engines, the small bumps on the runway, every small buffet of wind, the pronounced vibration — they were all a reminder that this plane was there. The men who flew it and the young men it carried dove into hellfire.

That’s part of the mission of the Commemorative Air Force, which operates and maintains the C-47 and many other vintage aircraft. The group wants to keep the stories alive.

“Unfortunately, a lot of people now involved with this stuff are getting older and we need to get younger people involved so they understand what these airplanes and crew did,” said Steve Rose, the pilot of “That’s All, Brother.” “They don’t teach that in schools, and this is what’s great about the CAF: We have airplanes you can see, you can touch and you can get in.”

What started with one airplane in 1957 blossomed into a nationwide organization of pilots, enthusiasts and veterans seeking to keep the history and stories alive of the men and women who flew C-47s.

Rose said the plane travels to various air shows or displays and people — many of them children — ask how they got it there.

The answer is simple: “We flew there.”

“And the kids are always amazed,” he said.

Then it takes to the skies, occasionally with a team of parachutists.

That was the case for the 80th anniversary of D-Day when the plane toured Europe with the D-Day Squadron.

“The teams train like paratroopers and they do the whole process in the plane. So, there’s one guy who explains what’s going on,” he said. “The commands are the same as they did in World War II, shouting, ‘Stand up’ and ‘Hook up.’”

“And as that happened, the kids’ eyes light up,” he said.

Rose has been flying for more than 50 years. He spent 20 years in the Navy flying P-3 Orions, tasked with hunting enemy submarines throughout the Cold War. After that, United Airlines offered him a job and spent a career that spanned about 21 years.

Rather than sit about after, he joined the Commemorative Air Force.

“That’s All, Brother” was not the only airplane on the ramp at Wings Over the Rockies’ Exploration of Flight, nor was it the only warbird to grace the skies of the Denver Metro area.

Friday’s flight saw “That’s All, Brother” joined by a B-25J Mitchell called “Yellow Rose.” Last week, the B-29 Superfortress named “FiFi,” one of two airworthy examples left in the world, wowed crowds at Rocky Mountain Metropolitan Airport before flying down to Colorado Springs.

Named for the trailblazing Col. William “Billy” Mitchell, B-25s were the first American planes to attack Tokyo during World War II.

Though an inconsequential raid strategically, it was immeasurably important according to Dawn Robinson, one of the volunteers with “Yellow Rose.” The Doolittle Raid showed the Japanese the USA would not roll over and sue for peace as they’d hoped the country would after Pearl Harbor. It also signaled to the Japanese that America can penetrate their homeland, delivering both a physical and psychologic shock.

“Col. (James ‘Jimmy’) Doolittle said, ‘I’ve got this.’ And (he) picked this particular type of airplane, trained 17 crews and they took off from the USS Hornet in the North Pacific,” Robinson said. “We bombed Tokyo and got inside the head of the Japanese and they realized, ‘Oh no, we could be attacked.’ The raid didn’t do any real damage, but we got inside their heads.”

The raid demonstrated the dangers of American Navy aircraft carriers, indirectly setting the stage for the climactic Battle of Midway — which took place on June 4-7, 1942 — resulting in the Imperial Japanese Navy losing four irreplaceable aircraft carriers.

B-25s served in every theater of World War II, from the frigid steppes of Russia to the forests of Europe and the tropical Pacific. They served to the end of hostilities and just under 10,000 were built. Only 45 remain airworthy today.

“Yellow Rose” did not see combat service, it was built too late to be involved, and the Central Texas Commemorative Air Force Wing now keeps it airborne. “Yellow Rose” did not fly on Friday morning, though flights are available for sale over the weekend.

“When you’re flying these things, they’re distinctive sounding because most airplanes don’t use radial engines anymore,” B-25 pilot Kevin Ritchie said. “Once you fire these things up … you can’t miss them.”

That’s true for several reasons, the crew explained.

Notably, they’re loud.

During the war, pilots and copilots would become deaf in one ear, depending on where they sat through their tour of duty, Robinson said. Even with modern ear protection, the noise is borderline uncomfortable, the crew said.

Friday’s flight brought the history of World War II to life.

Living history flights aboard “That’s All, Brother” are $275 per passenger and “Yellow Rose” are $450 to $650 per passenger. Ticket sales help keep the aircraft maintained and in the air and can be purchased at www.centraltexaswing.org.

Attendees can also visit the Vietnam Helicopter War Museum, which will be on site for the weekend.