It’s official: AeroBalloon will fly in China. It took three rounds of meetings in Beijing, a complete redesign of the passenger-carrying gondola, and too many sleepless nights to count. I attended the two latest meetings virtually, working from the comfort of my home between 8pm and 5am for a total of nine nights. If I am relieved to put those nights behind me, I can only imagine how my client Doug feels.

The Chinese are thorough and unapologetic, and the Chinese code – and the inspectors’ interpretation of it – is gospel. Some of CSEI’s demands were trivial, even comical. AeroBalloon specifies regular pre-flight equipment checks with a daily, weekly, monthly, and semi-yearly schedule. But in China, YEARLY inspections are required. Doug copied the semi-yearly schedule and presented it as a yearly schedule, and that satisfied Mr. Li.

Other demands were reasonable, albeit annoying. In October, Mr. Li asked for technical drawings showing every detail of how the balloon is assembled, like an IKEA instruction set, plus tables providing the manufacturer, material, dimensions, strength, and nondestructive load testing method of each part. It took two months, and a dedicated drafter (who traveled to China for the January and February meetings), for our team to develop our drawings to the required level of detail.


First sheet (of 22) of gondola assembly drawings, drawn by our drafter Jaguar.

And then there were the demands that almost sank us. According to the Chinese code for tethered balloon rides (yes it exists), the passenger-carrying device is required to have a metal frame. Our original gondola consisted of eight fiberglass modules, connected via eight aluminum ribs which transferred passenger weight from the modules to the suspension cables. In our inspectors’ opinion, the ribs didn’t count as a frame. Our design was more than sufficient structurally, but deficient based on this technicality. We had no choice but to change it.

Most infuriating were the demands based on no code at all but the inspectors’ personal preference. In October, even though our gondola handrails exceeded every railing-height code we knew of (and passengers were required to wear harnesses to boot), CSEI would approve nothing less than a full cage of netting surrounding the gondola. Another substantial design change was required. Then, at the January meeting, they informed us our winch needed to have a backup brake independent of the brake we already provided. Cue frantic midnight calls to the winch manufacturer and, eventually, a month of further work.


A peek into the conference room where it all happened.

For my part, Mr. Liu asked for a risk analysis of every single part, including nonstructural items like the helium release valve (which is almost never used and would not affect operations in any substantial way if it malfunctioned). Once my list of over 40 failure modes satisfied him, he requested additional calculations for several wind speeds unrelated to AeroBalloon operating procedures, and a fatigue analysis for all pins. No reason to complain; I put my head down and churned out the calculations that the CSEI inspectors needed to check their boxes.

And now it’s all paid off. AeroBalloon aims to launch its first AB-40 in Chengdu this summer. And Doug has invited me to attend. These are exciting times for little PERCH.

China Week: The Great Wall

He who does not reach the Great Wall is not a true man.
-Mao Zedong

I saved the best for last. The Chinese call it 万里长城, pronounced “wànlǐ chángchéng” (literally “the 10,000-mile-long wall”), or simply 长城 “chángchéng” (“the long wall”). Archaeological surveys place the total length of all sections of the wall between 5500 miles and 13,000 miles. Thus, even though the number “10,000” is meant to be figurative (like “myriad”), it turns out to be an accurate description.


Doug traverses an unrestored part of the Great Wall.

Semantics aside, the Great Wall is truly great. The oldest parts were built nearly 3000 years ago, but the parts still standing today were largely built or rebuilt during the Ming Dynasty of 1368-1644. The wall traverses some of the most rugged terrain imaginable. Guard towers spaced by sightlines allowed sentries to keep an eye on the empire’s entire northern border, and enabled rapid communication. The wall aimed to stop nomadic invaders long enough for China’s armies to mount a defense. It didn’t always work.

Today’s wall is the product of tens of millions of laborers. Typically each side is a double course of brick sandwiching rubble. Two colors of brick are used, with the tan parapet standing out from the grey bulk. Here’s a new vocabulary word for you: crenellation. The Great Wall’s parapets have a crenellated, or toothy shape, rather than being solid. The low parts are called crenels, and they’re useful for shooting an arrow at an invader or for admiring a view.


A cross section of the parapet.

The 4- to 5-meter-wide interior is filled with rocks and earth, and paved over on top with stones. Touristy sections of the wall have stairs, while crumbling unrestored segments are slippery smooth. The stairs include periodic channels carved out for drainage. Guard towers typically have window openings and a terrace on top accessed by narrow steps.

A handful of restored wall segments near Beijing are the most visited. These segments charge admission fees and offer refreshment and souvenir stations, as well as amusements (for an additional fee) like chairlifts and toboggan rides. One may traverse the natural parts of the wall between restored segments, and overnight point-to-point trips are popular with backpackers.

I imagine the builders would be proud that their life’s work survives as not only China’s most iconic monument, but also the world’s first long distance hiking trail. It’s a pretty simple one to follow.


This concludes China Week. Please read the first six parts if you missed them: Architecture, Business, Food, Pollution, Bridges, and Transportation.

Tiny Tuesday: Transportation in China

China has far more cars on the road than it did 20 years ago, but cheaper, less fuel-intensive modes of transportation remain the most popular. We’re not just talking bikes and mopeds, but an endless variety of vehicles.

Bicycles are supported by tons of infrastructure: major roads have fully separated bike lanes, and street corners have secure bike storage areas. Many bicycles are equipped with baskets to carry groceries and passenger seats to carry family members. Three-wheeled bikes fill the role of pickup trucks, with a durable and versatile cargo bed. It’s not uncommon to see stuff piled six feet high. Cargo nets and bungee cords hold the commodities in place.


Lots of three-wheel, pedal-powered carts parked on a hutong.

Perhaps the most popular vehicle of all is the electric bike… a godsend when you travel long distances, up hills (Beijing is in a pancake-flat valley but the mountains are less than 50km away), or carrying heavy loads. Runner-up in popularity is the scooter, which does away with pedals entirely and runs purely by motor. All the modes I’ve mentioned so far are effectively immune to traffic laws – they’ll run red lights, weave through traffic, and even drive on the wrong side of the road. It’s with good reason that China prohibits most foreigners from renting a car.

Speaking of which… even the fully enclosed, fully motorized vehicles come in such variety that it’s hard to define where a “car” ends and another category begins. There are rickshaw-like vehicles with a basic box for weatherproofing, seating one driver in front and two passengers squeezed in a back seat maybe a meter wide. There are three-wheeled miniature cars resembling India’s Tata Nano, and tiny four-wheelers reminiscent of America’s Smart ForTwo. And then… sedans, crossovers, SUVs galore.


Traffic jam at a tollbooth on the city outskirts.

For those who prefer to avoid the traffic jams, or at least leave the driving responsibilities to someone else, public transportation abounds. The Beijing metro is the cleanest and fastest transit system I’ve ever ridden. Rivaling the New York City MTA in size, its trains arrive every three to four minutes and cost less than a US dollar to ride. Safety is a priority: riders must pass their bags through a security check, and in most stations glass walls separate the platform from the track, with doors opening only when a train arrives. Beijing also has an extensive bus network and a fleet of green-and-yellow taxis, steered by who are surely the nation’s boldest drivers.

For an American I’m pretty average in my transportation impact – I combine errands and I carpool when possible, which isn’t often in rural Vermont. After two weeks in Beijing I’m reevaluating my options. Can I add cargo capacity to my bicycle? Can I add handlebar-covering mitts, like Beijingers do, to keep my hands warm and extend the cycling season? Should I invest in an electric bike? Move closer to a city? I have the luxury to make these choices, and if I’d worried about climate change then I had better do my part.


Bicycles, skinny vehicles, full-width sedans, and pedestrians share the road.