most challenging category for a two-person team, the Dynamic 2-way competition.

“They’re just determined, and they train really hard,” said Laura Wagner, communications coordinator for the International Bodyflight Association, a Texas-based sanctioning body that hosted the national competition this spring as a qualifier for a worldwide championship in October. “They’re really focused.”

With sky divers for parents — mom Julie has 2,000 jumps and dad Mike has 15,000 as part of a pro sky diving career from which he recently retired — the Wittenburg kids have easy access to coaching.

And with a flight chamber in their hometown of Naperville since iFly opened in 2014, they have a convenient place to practice up to five times a week after school.

“It’s every kid’s dream to fly,” Noah says after wrapping up a recent training session with his sister and dad.

“It’s really free. You just feel like every kind of bird there is.”

As Dynamic 2-way winners at the first national competition, Kaleigh and Noah qualify for the World Indoor Skydiving Championship this fall. But as a 10-year-old up against an international age minimum of 12, Noah’s youth for once plays against him. Kaleigh is preparing for an individual event at the world competition, but Noah, who’s also an avid skateboarder and football player, will have to wait his turn.

Some sky divers discount the young duo, but Wagner’s seen them in the tunnel and says they’re the real deal.

To become champions at nationals, they won two separate elements of the competition: A speed round during which participants aim to complete a series of specified movements as quickly as possible without “busts,” or penalties, and a free round during which athletes choreograph their own routine and are judged on difficulty, skill and form.

“We hear a lot of arguments like, ‘They’re smaller, of course they’re faster,’” Wagner said.

“But they also win the free rounds where it takes the creativity and the memory and the skill to do really hard tricks.”

Against machine-made wind speeds of 130 to 150 mph, Kaleigh and Noah step into the flight chamber, lean their lithe bodies into the fast-moving air and immediately take flight. For some moves, they follow the leader. For others, they become mirror images.

Moves like the flip-twist, Noah’s favorite, are impressive to behold, judging by the reaction of a group of Chinese tourists, who stopped by iFly one afternoon when the kids were in the tunnel.

Their smartphones trained on the flight chamber, the tourists oohed, aahed and applauded at the championship display.

“To look cool, you’ve got to do it in sync,” Noah said. “It requires eye contact.”

After school each day, Mike Wittenburg, who owns a landscaping company, picks up his kids and shuttles them to iFly. The three of them step into flight suits, insert orange ear plugs, slide on helmets, set up a GoPro camera and take to the air.

Later, after homework, they review the footage and talk it over to critique their movements.

“You can fly and basically do whatever you want in the space you have,” Kaleigh says.

Kaleigh took her first indoor flight when she was 5. Her parents saw a light in her eyes that showed she was a natural.

Noah, 3 at the time, says he remembers crying at the noise of the massive fans that create the wind; he stood on the stairs to the flight deck, refusing to get any closer.

A couple of years later, though, he was ready to take flight.

The Wittenburg siblings already have become quite the globe-trotters in their pursuit of sky diving, competing 14 times in places including Italy, New Zealand, Hong Kong, the United Kingdom, France, Poland and Spain. For five years while Mike was sponsored by Skydive Dubai , the family lived there.

“As I got older and retired,” said Mike, 41, “they kept competing.”

Noah says he thinks he’ll pursue sky diving competitively for a few more years. His sister says she doesn’t foresee losing interest anytime soon.

Training together, the family developed hand signals for “redo,” “OK,” “wait,” “longer,” “done,” and “full routine.” Otherwise, in the tunnel, they communicate by screaming.

Sometimes, they spin so much they hardly know which end is up. That’s no obstacle.

“When you’re getting dizzy, you just kind of keep going,” Kaleigh says, “because you’re not going to get any dizzier.”