Out of a desire to understand a little more where my rockets could potentially land leading up to the launch, and the morning of launch. As well as predicting where anomalous flights may go(main at apogee failures anyone?) Especially after having treed a couple rockets in my close flying circle, I set out to come up with a way to hopefully predict where a rocket may land - GPS Drift was born (maybe someone can help come up with a more clever name). It is loosely patterned after high altitude balloon planning and prediction software. It's much less polished, and requires a bit of user input and manual work. I'd love to be able to automatically download forecasts like that software does, but that isn't in my toolkit.
The main user inputs are launch site latitude and longitude, apogee altitude and main deploy altitude for a dual deploy, as well as the descent rates under drogue and main parachutes.
The user then uses the Windy app/website to gather the windspeed and direction at each altitude up to your apogee. This takes a little effort, but isn't so bad once you get the hang of it. For a rocket flying to 5500 feet, it requires 7 points.
Then there's a few more clicks and utilization of a website called GPS Visualizer, which takes our data and puts it into a KML file for later viewing. This is how I gathered the picture above.
The estimated landing site GPS coordinates are also provided and highlighted (light purple) in the sheet.
*Disclaimer, I haven't been able to put this software through its paces yet. It's just now getting warm enough in MN to hopefully start flying again in the next month or so. Began development in December of 2020.
I just wanted to get it out in the wild, and see what others think, as well as their experiences. If you use it, was the prediction even close? Maybe there are ways to improve it?
I'm not looking to develop a full launch simulation. However, a predicted landing location in my mind is one of the biggest things simulations could provide. Especially if they are based on actual wind forecasts.
The help sheet provides a pretty thorough walkthrough of what is needed to perform an analysis.
Please post your feedback, questions and comments here. Would love to hear what you think, and if there any ways to make it better!
Thanks,
Dave