Written by Blake Raab (N4BWR)
It's launch day! We will be meeting at 9 AM at the VFW Fairgrounds (1625 Bankhead Highway, Carrollton GA). We plan to launch around 10, or whenever everything is ready. See this link for the current flight prediction. Keep in mind that varying ascent or descent rates will stretch or compress that part of the path, but the general shape of the flight prediction is what to watch. Take a look at the predicted burst point and landing site. The distance between them is 5.0057 miles, and the heading from burst to landing is 284.55 degrees. Once we know the actual burst point, we can get very close to the landing site before it lands by using this tool to calculate that point based on distance and heading.
We will begin communications on the W4FWD repeater (146.640, negative offset, 131.8 hertz tone), See the Incident Radio Communication Plan linked below to see the repeater, balloon, and APRS frequencies. We may use the balloon uplink frequency for simplex communications on the ground at the landing area. The WB4GNA repeater is also a good alternative (147.090, positive offset, 131.8 hertz tone).
You can track the balloon on aprs.fi here. In that link, I've set the track tail length to three hours to cover the whole flight. If you would like a way to track the balloon alongside the prediction on your mobile device, you can click here, save the KMZ file to your device, and open it in the Google Earth app.
Flight Day Resources:
- ICS-205 Incident Radio Communications Plan - For a list of the frequencies used for tracking the balloon and communication
- N4BWR's Weather Balloon Trajectory Map - Updated at least every morning with the latest prediction for launch day. After 8 AM on 7/10, that will be the operational map for launch day.
- Tracking of W4FWD-11 on aprs.fi - You can use this site on any computer or mobile device to track the flight of the balloon in real time. Click the balloon icon to see details, including altitude. You can also click on any of the previous red dots on its track for the same information at that point.
- Live Tracking Alongside Prediction - If I remember to update this file (which is a big "if"), you will be able to view the current flight path along with that day's prediction in the Google Earth app on your device. As of the time of this writing on 7/9, the predicted flight path shown in the file is for a flight we had last year.
- Find Terminal Coordinates, Given a Bearing and a Distance - This is a fun one. I have found a highly accurate method to pinpoint where the balloon will land once actual burst has happened by taking the compass heading and distance between predicted burst and predicted landing and applying that once actual burst has happened. This is the site where I will be plugging in the actual burst point and the predicted distance and heading to find the endpoint. I will certainly be announcing this information over our text group and any radio frequencies we're using at the time, but will probably also let everyone know that morning what the predicted distance and heading is so you can plug that in yourself.