The Ballometer is a sensor box for hot air balloons. It allows pilots to measure and log flight data such as GPS position and velocity, barometric altitude and vertical speed, relative humidity and more. The measurements are stored on the device and if you connect it to the internet via a mobile phone wifi hot spot, it will send the measurements to www.ballometer.io. Like this your friends can track you in real time. The flight measurements are archived online and ordered by date. This allows you to share memories of old flight with others in the future.
I started working on this electronics project because I wanted to understand better how environmental parameters such as air humidity or solar irradiation influence fuel consumption. In the ballooning community people make strong statements about this but I could not find any studies. I am interested in quantifying the different effects such that maybe one can build more efficient hot air balloons in the future. The Ballometer might help providing the relevant data for this.
A small display and a few buttons allow the pilot to connect the Ballometer to a wifi hot spot of a mobile phone. The measurements are presented on a website that can be opened by any device in the same wifi network. All you have to do to see the data is open up the website in a browser and no installation of further apps on a tablet or mobile phone is required. When mobile data is available, the Ballometer will stream the measurements to www.ballometer.io and others can track your flight in real time.
The Ballometer box is small enough to be mounted on a burner support by a Velcro strap. The housing has to be big enough to hold a 10000 mAh power bank which has typically the size of a large mobile phone.
For navigation purposes the Ballometer website contains a map with the current balloon position, projected direction, and a flight track. The map covers the entire world and is based on roughly 55 gigabytes of OpenStreetMap data which is stored in the Ballometer.
All measurements are stored locally on the Ballometer and the measurement history is available to the pilot even without an internet connection. The online website also stores the measurements and presents them for future use ordered by flights. All data sent to the website is open for everyone without access restrictions - pilots can however delete flights from the website.
The operating system on the raspberry pi is raspbian light. Scripts written in python read out the sensors over serial and I2C and store the measurements in an influxdb time-series database. Adafruit libraries facilitate the communication with the sensors. Grafana presents the measurement history on a website and maptiler-gl delivers OpenStreetMap data. The web frontend is written in react and a node server runs in the backend. Ansible helps documenting and automating the configuration of the raspberry pi and also the online server.
The idea of building something like the Ballometer was in my head for a long time. I remember that I wanted to make a website already in 2015 for logging a phone’s GPS data during a hot air balloon flight but never got very far with writing an android app. Later a friend of mine got an isolated envelope and we started discussing about fuel consumption. Especially during the night this balloon uses much less fuel than conventional ones. Many pilots think that this is related to the increased relative humidity during night, but I think it has rather to do with missing solar irradiation.
In autumn 2019 I started the website www.ballometer.io and implemented a flight tracker. Most of the sensors worked immediately but the solar irradiation sensor still requires some work as the sensitivity depends on the angle between the sun and the sensor. I plan to compensate this by measuring the orientation of the sensor with a digital compass.
To make a plastic box I started experimenting with 3D printing in November 2019. Although this technique is a bit slow, it is inexpensive and well suited for making a custom enclosure.
I would like to build a few Ballometers and sell them to other hot air balloon pilots. They will get a username for the ballometer.io website which is based on their family name, like for example ballometer.io/wipfli. I am interested in collecting like this flight data under different conditions. In the future this data can be used to model the influence of the observed environmental parameters on fuel consumption.
The schedule looks like this:
The Ballometer is based on inexpensive and mass produced components and AliExpress sells most of them. The official Raspberry Pi reseller for Switzerland says that the Model 3B+ will only be available in June 2020, but maybe I can receive some before this date from another distributor.
The following table gives an estimate of the material cost:
|Component||Lead Time||Price (CHF)|
|Raspberry Pi Model 3 B+||09.06.2020||40|
|SHT 31 Temperature Sensor||60 days||3|
|LSM303 Compass||60 days||3|
|TSL2591 Solar Irradiation Sensor||60 days||5|
|BMP280 Pressure Sensor||60 days||1|
|Mini USB Microphone||60 days||2|
|GPS UBlox Neo 7M||60 days||12|
|GPS Antenna||60 days||2|
|LCD Display||60 days||4|
|SD Card 64 GB||60 days||15|
|Power Bank 10000 mAh||14 days||30|
|3D Printed Box||14 days||10|
|Printed Circuit Board||14 days||3|
There will be a fee for the labor needed for assembly which is roughly CHF 50. Shipping is likely to cost another CHF 20. This will lead to an overall cost around CHF 200.
Hot air balloons seem to be so simple systems that I belief it should be possible to model them with a high degree of precision. The Ballometer captures the main physical factors that determine the dynamics of a hot air balloon and it paves the way to a quantitative model of fuel consumption based on environmental parameters. I hope that a better understanding will lead to more efficient hot air balloons in the future.
Besides these scientific ambitions I also just want to make pilots able to share their flights with friends. ] I am sure that having the flight history available online will invoke many good memories when looking at the tracks at a later point in time.
If you have questions about the Ballometer feel free to contact me via the form on my ballooning website https://leichteralsluft.ch/#contact.