Re: HAB predictions

Mark Jessop

As others have said, the predictor accuracy is often mainly limited by the user inputs (e.g. ascent rate, burst altitude and sea-level descent rate), and how closely your flight actually achieves these.
In particular, your burst altitude is going to play a big part in this. If you are not using a well-characterised balloon, then calculators like will not be good at estimating this.

As for your RTTY code, I suggest digging into code from a known-good tracker like this:
This also has code to add a CRC16 to the end, which is pretty important with a mode without error correction like RTTY...

Mark VK5QI

On Thu, Mar 16, 2023 at 7:59 PM Steve G8KHW / AJ4XE <steve@...> wrote:

In my experience the error is greatest in the direction of travel - less so at right angles to it.   I suspect the predictor is quite accurate - its the other factors that cause most of the error.

    Steve G8KHW / AJ4XE

On 15/03/2023 23:49, Dennis Klipa - N8ERF wrote:

I am sure results vary, and depend a lot on the accuracy of the input and how recent the winds aloft data is. Getting the "neck lift" accurate under windy conditions can add a significant error. My experience over only 12 launches is +/- 10% of the total distance traveled.  So, IMHO, the observed error in the prediction is not with the code but with the parametric input.

Happy flight!

Best Regards,
Dennis, N8ERF

On Wed, Mar 15, 2023, 7:06 PM Sasha Tim <sasha.nyc09@...> wrote:
Hey all,

In general, how do the predictions of the CUSF engine ( compare with the actual landing site? I've heard the figure of +- 2 miles. What is your opinion on this?

Still working out a few RTTY transmission bugs with my payload, then hopefully launch this week! Code is here If anybody could help figure out why the longitude doesn't always transfer correctly (occasionally, it just skips a digit in the decoder, although the datastring[] is always fine) it'd be wonderful!!!!.


Sasha VE3SVF

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