About the airspeed indicator... I have four excellent books, all devoted to only Me-262 (and it's variants) but none of them shed any light for double needle thingy.
My educated guess would be that a) it's moving "top speed" marker which goes up but doesn't come down until you reset it manually. This would "record" maximum speed attained during the flight. B) Manual "redline" marker, ie speed you should not exceed for some operation, like for example you shouldn't lower the landing gear until below 400 km/h... but these are only guesses.
Leaving it off altogether wouldn't probably matter unless you're doing true simulation instead of arcade-ish game.
BTW, have you checked these:
http://www.zenoswarbirdvideos.com/Images/Me262/262PilotHandbook.pdf
http://www.zenoswarbirdvideos.com/Images/Me262/ME262PILOTDEBRIEF.pdf
http://www.zenoswarbirdvideos.com/Images/Me262/ME262WendeL.pdf
My educated guess would be that a) it's moving "top speed" marker which goes up but doesn't come down until you reset it manually. This would "record" maximum speed attained during the flight. B) Manual "redline" marker, ie speed you should not exceed for some operation, like for example you shouldn't lower the landing gear until below 400 km/h... but these are only guesses.
Leaving it off altogether wouldn't probably matter unless you're doing true simulation instead of arcade-ish game.
BTW, have you checked these:
http://www.zenoswarbirdvideos.com/Images/Me262/262PilotHandbook.pdf
http://www.zenoswarbirdvideos.com/Images/Me262/ME262PILOTDEBRIEF.pdf
http://www.zenoswarbirdvideos.com/Images/Me262/ME262WendeL.pdf