Pro track accuracy?

[MooChooser 0]

Ive just got myself Jump track software so today I thought Id try tracking to see how slow I could get my vertical speed.

The graph is a fairly smooth curve with the highs and lows in the places i'd expect from how the jump went.

Heres the suspect part, at its lowest, the graph shows my speed at 40mph.
Is it possible to fall that slowly in a track with just a freefly suit on?

[jurgencamps 0]

The opening of your parachute?

[MooChooser 0]

Ha, im not that stupid.
The graph shows an initial acceleration to about 150 as I exited head down. I transitioned slowly into a tracking position and the graph shows my speed decrease steadily until 5000 feet where it registered as 40mph. My ditter went off at 5000 so I stopped the track at this altitude and the graph shows an acceleration to about 110 at which point I deployed.

[quade 3]

The ProTrack, while a GREAT device (I have several myself and have used them for years) is only useful IF you understand how it works.

In it's most basic terms, it's a barometer that records over time.

If it is in a fairly stable location that isn't going to change orientation and location in the wind stream very much, it's pretty darn nice.

On the other hand, if it is tumbling and going into and out of the high and low pressure areas around your body, then there's going to be some pretty wild fluctuations in the readings as it does this.

If you ever wanna see how this works in real time, back fly for a bit and watch your wrist altimeter as you hold your arm away from your body and then move it over your belly.

I can not in my wildest imagination believe you actually got down to a vertical speed of 40 mph in a track with just a freefly suit on.

quade -
The World's Most Boring Skydiver

[pchapman 261]

Quote

The graph shows an initial acceleration to about 150 as I exited head down. I transitioned slowly into a tracking position and the graph shows my speed decrease steadily until 5000 feet where it registered as 40mph.

Yeah I figure it is an artefact of changing body position. When tracking for separateion at the end of a bellyfly jump, I fairly consistently get a big, wide spike to 140+ mph. While the body position and airflow changes aren't that big, the gadget is clearly getting fooled.

As I've said in some other ProTrack thread, if you want to dig more, export the track to a text file, import into Excel, and do your own averaging. The JumpTrack graph bases its numbers on averaging the previous 6 seconds of flight -- so there's a lag as well as data smoothing going on. That confuses the issue when it comes to comparing a particular speed at a particular altitude. I prefer a centered 3 second average to avoid the lag, but still provide some smoothing. (So each point on the graph is the average of all the quarter second data points from -1.5 to +1.5 seconds). I believe the ParaLog program on the market allows a similar averaging.

[aguila 0]

Did you mount your protrack inside your helmet?

If you want to use its full features you must mount it on you wrist or leg. (of course you can not use it as an audible altimeter then)

Gonzalo

It cannot be done really means I do not know how to do it ... yet

[Quincy 0]

To add to what Quade was saying, having it in a consistent air stream is important. I have a Pro-Dytter in my helmet and the Pro-Track on my ankle. The fluctuations now seem to make more sense with what you would expect from different elements on the jump.

Quincy...