HIGH-ALTITUDE BALLOONING 101
EQUIPMENT & PAYLOAD ITEMS
Each one of our high-altitude balloon flights includes two main components—the balloon and the payload train. The payload train consists of all the payload items that the balloon carries during flight. For all of our K-12 launches, this includes: (1) a parachute, (2) a GPS flight computer, (3) a backup GPS tracking device, (4) video cameras, and (5) student experiments. All of these are attached to each other via a system of nylon harnesses and high-strength cords. Aside from the student experiments, we bring all of the payload items with us on launch day.
BALLOON
We use high-quality latex weather balloons from several different manufacturers, usually either Kaymont or Hwoyee. There are many balloon sizes available (given in terms of mass), from 200 grams up to 4,000 grams. These range in price from about $20 for the smallest balloons to over $400 for the largest. Smaller balloons are intended for lighter payloads, have a smaller burst diameter, and thus have a lower maximum burst altitude. We typically use mid-size balloons, either 1,200 grams or 1,500 grams, which typically allow us to achieve burst altitudes of 90,000+ ft for the payloads we fly.
PARACHUTE
The parachute is placed at the top of the payload train, between the balloon and the rest of the payload items. It acts to slow the payload train’s descent back to Earth after the balloon bursts. Since we only fly payload trains that weigh 12 pounds or less (see the FAA Rules & Regulations section), a 6-ft-diameter parachute is all we need. This is large enough that our descending payloads usually land with a vertical descent rate no more than ~1,500 ft per minute.
FLIGHT COMPUTER
The SatCom (Satellite Communication) flight computer that we use was developed by Stratostar, an educational high-altitude ballooning company with whom we occasionally collaborate. The SatCom includes GPS tracking technology and is equipped with a suite of basic sensors to measure environmental conditions during flight (e.g., air temperature, air pressure, relative humidity, acceleration, and rotation). It also uses GPS measurements to calculate its horizontal speed and direction, which serves as a proxy for wind speed and wind direction. During flight, the SatCom transmits its data to the Iridium satellite network about once per minute. The satellites then send the data directly to the internet, allowing us to monitor the data and track the payload in real time from our computers or smartphones. The data are also saved to an onboard SD card every 5 seconds.
Balloons
Parachutes
SatCom Flight Computer
BACKUP GPS
In the event that we have issues with our flight computer after launch, we also include a small SPOT Trace GPS device on the payload train as backup. The SPOT Trace transmits its location to the internet via satellite every 10 minutes. It tends to have extraordinary battery life and can usually track continuously for several days.
VIDEO CAMERAS
To capture highlights during the flight, we typically include multiple video cameras on the payload train. In fact, we have designed a special payload box that allows us to mount our cameras in certain ways. This box typically includes three GoPro HERO5 Session cameras, each pointing in a different direction (up at the balloon, down toward the ground, and sideways toward the horizon). We record footage at 1080p resolution (1920 x 1080 pixels) and 60 frames per second. For longer battery life, each camera is connected to an external battery pack that allows the cameras to record continuously for up to 3 hours. If requested, we can provide the raw video footage after the launch.
More recently, we’ve also started flying an Insta360 camera mounted to the outside of our video camera box. This provides us with immersive, 360-degree video footage during flight (see an example here), in addition to the more traditional angles of view obtained from the GoPro cameras. The 360-degree camera captures footage in all directions at 5.7K resolution (5760 x 2880 pixels) and 30 frames per second. We’re still working out some of the kinks with this new camera, but we expect it to become a valuable tool in our video recording arsenal.
STUDENT PAYLOADS
The K-12 student participants are expected to contribute to the payload train as well. We send the teacher a set of empty foam boxes weeks before the launch, free of charge. Our payload boxes are custom-made. However, teachers are welcome to use their own payload boxes as well, especially if you need something larger than what we provide. The students can then use these boxes to house their experiments during flight. The student payloads will be discussed more in the Developing the Student Payloads section.
SPOT GPS Trackers
Cameras
Radiosonde
OTHER EQUIPMENT
For higher quality atmospheric data, we now have the ability to attach a small radiosonde device to the bottom of the payload train. Our radiosondes are lightweight (0.2 lb) sensor packages that measure temperature, humidity, air pressure, wind speed, and wind direction during flight. They transmit their data back to a ground station via radio signals once every second. The data they obtain, specifically temperature and humidity, are much more accurate than those obtained from the sensors on the SatCom. In fact, the National Weather Service flies this exact same model of radiosondes each day from many of their offices.
We use iPads to interface with the SatCom prior to launch and to remotely monitor the SatCom data during flight. A brass regulator valve and filler hose allow us to safely control the flow of helium while filling the balloon. During the filling process, we attach a small digital scale under the balloon to measure the balloon’s free lift, which determines how fast the balloon will ascend. A combination of zip ties and a PVC pipe allows us to secure the payload train to the neck of the balloon. Payload rigging is necessary to attach the payload items to each other. For this, we use a combination of twine or paracord, fishing swivels, and custom-made nylon harnesses.
Other miscellaneous supplies we use include tarps, gloves, electrical tape, and hand tools. Smartphone GPS apps and handheld GPS devices, loaded with public and private land maps, are very helpful during payload recovery. We also have physical BLM maps that cover the entire state of Wyoming.
WHAT EDUCATORS NEED TO KNOW
Since we bring all of the equipment with us on launch day, the only payload items that teachers/educators are responsible for are the student payloads.