I have been using Hobbs time to record flights up until today when I decided to start using Tach Time. I set the tach time to the same as the hobbs and the cruise rpm setting to 2500. I then flew 2 flights.
The first started at 44.9 Tach and ended at 45.6 and the hobbs at 45.8, about right for the flight cruising at around 2300.
The next flight back to base was the same length and cruise setting but the tach time ended at 46.7 same as the tach. i.e. tach was running faster than real time despite the engine rpm being less that the cruise setting. :-?
Once I stopped the engine I noticed the tach time alternating between 46.7 & 48.? However I suspect this may be because I altered the time and it was showing the original and new times.
The first started at 44.9 Tach and ended at 45.6 and the hobbs at 45.8, about right for the flight cruising at around 2300.
The next flight back to base was the same length and cruise setting but the tach time ended at 46.7 same as the tach. i.e. tach was running faster than real time despite the engine rpm being less that the cruise setting. :-?
Once I stopped the engine I noticed the tach time alternating between 46.7 & 48.? However I suspect this may be because I altered the time and it was showing the original and new times.