I have wondered this myself. I sort of have two (sort of complimentary) reactions when I do:
- At some level, if I'm playing with old technology, I like to be true to that tech. Even if it worked better in the lab than it does out in the field. Someone designed it to work a certain way. OK, let's set it up to function that way.
- It would be interesting to find out how well it does work, in the cabin of a modern, pressurised airplane flying five miles up. Do a few experiments and report on them.
As for how well it does work, we have among FPN's members a fair number of people who have flown with an Aero 51, long tube, hole near one end, and who ought to be able to tell us what happened. When I was doing it with the original silver tube, no problem. Year in and year out.
Others will perhaps have had different experiences. And can tell us, if they so choose. It is something like an experiment that has been done very many times.
An important point here is that my having no significant leakage doesn't mean the hole with certain specifications was *necessary* for my happy outcome. For a proper experiment we'd have to have people also flying with pens different from what Parker manufactured.