[Cap'n Wannabe]

Just had another discussion with my mate..

Take the Extra 300. It carries 40 litres (38 usable) in the acro tank, and 120 litres in the wing tanks.

Section 2.4.1 in the POH reads:

Fuel

Minimum grade aviation gasoline : 100/100LL; for alternate fuel grades see latest revision of LYC S.I. No. 1070
Total fuel capacity 160 litres (42.3 US gallons)
Useable fuel capacity 158 litres (41.7 US gallons)
For acrobatic flight wing tanks must be empty
Total fuel capacity for acrobatic flight 40 litres (10.6 US gallons) in acro tank
Useable fuel capacity for acrobatic flight 38 litres (10.04 US gallons) in acro tank

Bolding mine..

So if you were to fly a competition, or even practice, you'd start with 40 litres on board.

Fuel consumption on a standard day at 65% power is around 50 litres/hour (from a quick glance at the chart..)

Therefore, a MAYDAY would be required before you even start....at least, that's my understanding..