Hi

I am running SkyDemon version 3.10.10.20545 on a Nexus 7 tablet using the Android operating system.

I have started to have a logging problem relating to the recording of actual take off time and position. My aircraft is a slow flying powered parachute and doesn't fly fast enough to activate automatic logging so I always start the log immediately before engine start up and take off. GPS is active and I have a "fix" prior to take off.

Upon taking off the altimeter immediately becomes active and reports height gain but the position indicator reports the aircraft as "on the ground". This situation continues for several minutes, 14 mins on my last flight, before the position indicator reports a position by compass direction from a known reference point. The virtual radar appears to correctly display height gain that matches the altimeter reading immediately I leave the ground..

When importing the completed log into Google Earth the track is correct but the point of take off is indicated several miles along the track from the actual point of take off. This seems to coincide with the point when the position indicator changes from "on the ground" to a compass bearing from a known reference point. The elevational profile of the track in Google Earth shows positive height gain from the actual point of take off.

In the debrief pack the text appears to detail the time of take off coincident with the appearance of the positional information appearing from a known reference point on screen. This is incorrect as the actual take off time is several minutes earlier. The virtual radar in the debrief pack correctly shows height gain from the actual take off point.

This leads to actual flight time being incorrectly reported. I manually note the actual time of take off and landing anyway but it would be good to have SkyDemon function correctly in this regard.

Can this anomaly be fixed?

Regards

Glyn Pemberton

I'm afraid SkyDemon's algorithm for determining the point of takeoff is a simplistic one, and that is when your groundspeed first exceeds 30 knots. We could consider making this algorithm cleverer but wouldn't do so lightly, as a lot of functionality extends from this calculation and GPS-derived altitude is far, far less reliable than speed.

Thank you Tim for the quick response. Has the algorithm for identifying point of take off always been when groundspeed first exceeds 30 knots? The reason I ask is that the issue only appears to have become apparent after I downloaded the version I am currently running. I have looked at previous logs in Google earth and the take off point is literally within 2 minutes of log start time and in the correct geographical location. This would seem correct as I always start logs manually and then start the engine and then immediately take off.

Regards

Glyn Pemberton.

Yes, for several years this is how it's worked.

See above regarding reluctance to change this functionality lightly, as it works for the vast, vast majority of cases.