Don Terrill’s Speed-Talk

What does a spot flowing backwards look like with a pitot?

I know Jole Dubose swore by using the flow balls.

cspeier wrote: ↑Sat Feb 17, 2018 11:44 pm What does a spot flowing backwards look like with a pitot?

Should show negative dynamic pressure I'd guess; probably erratic due to turbulence induced by the upstream arm.

MadBill wrote: ↑Sun Feb 18, 2018 10:05 pm

cspeier wrote: ↑Sat Feb 17, 2018 11:44 pm What does a spot flowing backwards look like with a pitot?

Should show negative dynamic pressure I'd guess; probably erratic due to turbulence induced by the upstream arm.

Wouldn't that be easier to see with a string on a stick or even a bunch of strings on a stick? I suppose if you felt the need to quantify it, you could measure with the pitot, but why?... What you want to do is make it go away.

pcnsd wrote: ↑Sun Feb 18, 2018 11:02 pm

MadBill wrote: ↑Sun Feb 18, 2018 10:05 pm

cspeier wrote: ↑Sat Feb 17, 2018 11:44 pm What does a spot flowing backwards look like with a pitot?

Should show negative dynamic pressure I'd guess; probably erratic due to turbulence induced by the upstream arm.

Wouldn't that be easier to see with a string on a stick or even a bunch of strings on a stick? I suppose if you felt the need to quantify it, you could measure with the pitot, but why?... What you want to do is make it go away.

The flow ball kit I got came with flags also, the flag/string gives you direction, the proper size flow-ball gives you an idea of where to fill and how much is needed... at least in theory.

It seems more times than not the apparatus you stick in the port effects the measurement enough that it can not be duplicated without the apparatus in the port.