Hmmm, i'm feeling this is starting to get a little out of my depth - still have lots to learn and don't mind admitting so!
However, in answer to Big Pistons (and I say again, I am not trying to argue with those more experienced, just stating what I am taught):
However what ever method you use it is important that you truly understand what you are doing. From your post this does not appear to be the case. You say you want to RTB and no problem because you are on the 57 litre circle ?
I have to disagree with this statement I am afraid as I believe I do indeed understand fuel circles..a fact on which my instructor agrees! RTB on say in this example I quoted a 72 litre circle. The 72 litre circle is the first circle where we have used 3 litres in taxi and climb to the RVP. if the engine was to go bang at this point, we would only require three more litres to RTB. If however, the engine went bang at the furthest point on the trip outlined, we would have 66 litres to RTB and the minimum red fuel is 56 litres. PLanned fuel useage on the return leg is about 9 litres, so we are well in board.
This of course is indeed in still air, and one would have to recalculate in flight if there was a 25kt headwind, or for diversion etc. Fuel burn? Grob uses 25 litres in 1 hour. I would need to check if this was fully rich or leaned. But as this is the figure I am taught to use, and my teaching is not to lean, it must be the fully rich figure.
I do stress though, I am not trying to pretend I know more than I do...just interested to see how others are taught and if the military/ex military pilots out there agree that this is a worthwhile system or whether they when flying privately use GPS!
