Reminds me of the venturi tubes used to generate vacuum for the attitude
indicator in old Tiger Moths. I guess it was pretty reliable. Maybe these
things still have a place in modern airplanes alongside the computers ;-)

/ Nils

You don't have to go back that far! The vacuum system in my IFR equipped
1953 Cessna 170 was powered via a venturi. Works perfectly well
(as long as you don't run into to much ice) But that's why you
have an electric T&B

~Paul Mennen