There is one other aspect of vented header tanks 
and fuel systems in general that I would like to
mention and that is: 

What happens in a slip???? 

I have been in situations where I was low on fuel and 
the airport I was landing at made it advisable to slip 
the airplane in for one reason or another. Tall trees
at the end of the runway for an example. In the 182 with 
a strong cross wind it is advisable to both forward slip 
and crab. 

If you have your only pump or supply of fuel in a wing tank
the intake could become uncovered while in a slip and the engine
could quit. If the landing can be made engine-out no problem. 
If not well the go around will be exciting or not at all.

BTW I almost always slip for one reason only and that is
altitude is your friend. If you are draging it in.. in airliner
fashion... and the engine quits on final or base there goes 
your butt! Altitude is potential energy. Keep your energy up until
you are sure you can make a landing if the engine quits.

We lost an experimental airplane not too long ago at SZP because
the high time ATP failed to heed this principle. The engine
quit on final because of a fuel feed problem.

At controlled airports I keep it at high pattern altitude until
the last possible moment in case the controller gives me
an extended down wind.

It is a good idea to test slip your system at altitude 
with low fuel when you can make the airport no matter what.

Paul Lamar
 
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