Pitot design ass u mptions?
There appears to be no laws of dynamic similarity that would make a scaling up of the whole pitot probe inaccurate and I'm stretching myself to think of a problem with a 50 or 100% bore increase.
Airborne contaminants are generally small and large ones less likely to be homegeneously distributed, e.g. windborne detritus. Meaninga larger one might be more prone to detrital blocking but not 2 or all 3. Neither would one be as prone to complete blockage.
Obviously there is an optimum scale for a pitot probe, but has it been chosen too small.. key criteria to be considered are also inspection, cleaning, repair and corrosion (relative blocking ability)
I also can't see why the entry bore cannot be modelled smaller than the main bore and drain, as long as full pressure recovery is achieved, Q will be measured when V=0 at the transducer face. This could prevent larger scale detritus entering at all...
However, the manufacturers I accept, know a damn sight more than myself - even Thales - but are maybe working to a poorly conceived set of specifications (e.g. size, cost etc) that may indeed be quite historical and never reviewed for sensibility in many, many years...