Originally Posted by
milsabords
Pitot tubes can be clogged by dust, water or ice cristals because air flows inside from their inlets to their drain holes.
I imagine a tube w/o a drain hole, fed from the aircraft by a variable presssure air pump, controlled to deliver a fixed air flow. The internal pressure is a function of the outside total pressure at the tube inlet, therefore the air speed can be measured.
Side benefit: a simple test on the ground can detect clogging by insects or scotch tape.
There is such a device for measuring level in a tank - cheap and electrically 'intrinsically safe' known/marketted for nearly a 100 years as a
Pneumercator. Basically you set a small bleed flow via needle valve/ float gauge and you can calibrate a remote pressure gauge to display tank level.