The biggest hot air balloon in the US was built to carry skydivers

The plan is to soar up to 35,000 feet, and then five people will plunge out of it.
biggest hot air balloon in us
Inside the balloon. Shawn Raya

The biggest hot air balloon in the United States is designed to fly to an altitude of 35,000 feet or higher, carrying seven people in its rattan basket over New Mexico. Five of those people are then planning to jump out of it (wearing parachutes), plunging from an icy altitude where airliners typically fly but balloons rarely travel. Update on September 28: The team successfully carried out the jump.

Hot air balloons do not typically float up to such great heights. “Balloons don’t normally fly above 18,000 feet,” says Andrew Baird, the general manager of Cameron Balloons US, the balloon-making company behind this specific vessel. In fact, he notes, riding a hot air balloon up to 30,000 feet represents a special kind of milestone for anyone who does it. “It’s hard on the body,” he says. “You have to approach the mission scientifically, and with great caution.” 

Flying up to 30,000 feet in a balloon may be rare, but carrying so many people when doing so and even hitting 35,000 feet is “extremely unusual, let alone jumping out of the aircraft.” The purpose of the jump (which aims to break a world record) is to raise money for an organization called the Special Operations Warrior Foundation

Here’s what to know about the balloon that will carry these people to such a lofty place, by the numbers.

The balloon is designed to have a capacity of 560,000 cubic feet when fully inflated. Operator Solutions

560,000 cubic feet

This specific balloon is known as the A-560, with the 560 standing for 560,000 cubic feet. That’s the volume of the fabric part of the balloon. 

The fabric that it’s made out of is a kind of nylon known as Hyperlast, and it’s coated on both sides with silicone, says Baird. That silicone keeps the material from being porous.

[Related: The US military’s tiniest drone feels like it flew straight out of a sci-fi film]

“The purpose of a balloon fabric obviously is to trap air—we want to trap all that hot air because that’s what generates the lift,” he says. “We want it to be lightweight and flexible, but we also need it to be rugged, and slightly elastic.” 

“It’s the biggest balloon that Cameron Balloons US has ever made,” he says, although “a few” bigger ones exist in Europe. The company says it will measure about 113 feet tall when it’s inflated all the way.

1,069 pounds

All of that fabric and other related gear weighs more than 1,000 pounds, a figure that doesn’t include the weight of the basket and its burners. And of course, creating that fabric portion takes careful engineering and construction. A hot air balloon is not made out of one piece of fabric, but hundreds. One key component is called a gore, and these segments run longitudinally up and down the balloon. (This page has a helpful image.) “A gore is kind of like a segment of an orange—slightly bulbous, thin at the top, wider in the middle, and thin at the bottom again,” he says. This balloon has 20 gores. “And each one of those gores is made up of a number of panels that run horizontally.” 

The hundreds of panels comprise a type of “jigsaw puzzle,” Baird says.

“You have to know where each piece goes, you have to know which way up it goes, you have to know which way around it goes, and then you have to sew all of those together,” he adds. That sewing is done by people operating industrial sewing machines and joining the segments together with nylon thread, using a special seam. After the panels come together to form a gore, the team will begin to join the gores to one another. 

a hot air balloon basket
The basket is made from rattan, and the floor from synthetic plywood. Operator Solutions

4 burners

A hot air balloon needs burners to make the air in the fabric nice and toasty. This specific balloon has four. Two of those are “absolutely standard,” he says, and the other two have been “modified specifically for high-altitude operation.” If you want to float up to around 30,000 feet, the standard burners could do the trick, but going north of that altitude demands the special burners. 

The air in the fabric needs to be hot, of course, because that’s the reason the whole thing can fly. The process of launching a balloon starts with just regular air, on the ground, propelled in with fans. 

“Then we turn the burners on, and we heat that air up, and that air expands,” he continues. “And because the balloon is a fixed volume, as the air inside the balloon expands, some of it is forced out of the mouth—and the mass of air that’s forced out of the mouth is exactly equal to the lift that you generate.” An airplane gets its lift from its wings, a helicopter from its spinning top rotor, and in this case the lift comes from burning propane to heat the air. The less dense air in the balloon is lighter than the surrounding air. 

The basket that hangs below the balloon is made from rattan, and the floor of the basket is constructed out of a kind of synthetic plywood. He says it also has a “jump platform.” 

“They will congregate on this platform; they will link up, and they will all go out together,” he says. The initiative is called the Alpha 5 Project and the jump could happen towards the end of this month, although the window for the flight technically spans September 15 to October 15, and, of course, requires nice weather. 

The jump took place on Sept. 28. Alpha 5 Project

 

1,000 feet

This special jump involves traveling up very high. But when it comes to regular hot-air ballooning, Baird says that the magic number for having fun is much lower: “The fun way to fly is 1,000 feet or less—once you get above 1,000 feet, everything looks the same, just smaller.”

Being close to the ground in an open basket makes for a special kind of flight. 

“From a sightseeing perspective, the fun way to fly in a balloon is to be down low—if you’re out in the countryside, to come low, to dip down, get your feet wet in a lake, brush through the tops of the trees,” he adds. “Ballooning is unlike any other form of aviation, in that you are really part of the environment.” 

Update: The team successfully pulled off the jump on September 28. Watch a video of the plunge from the balloon, below.