Hercs from the archives (CHC)

[Splitpin]

[Charl]

Wowee on those prop tip vortices

[Splitpin]

Cheers Charl ...

Some more swirleys for you ...

[Charl]

These would be on take off so max power, max revs.
I am wondering how the C130 prop tip differs from others, you don't often see that elsewhere.
Or maybe I haven't been looking?

[chopper_nut]

I think it's a square tip thing but you do see it on the Q300s on humid days.

[deaneb]

These would be on take off so max power, max revs.
I am wondering how the C130 prop tip differs from others, you don't often see that elsewhere.
Or maybe I haven't been looking?

It will happen on any prop plane if the conditions are right. More likely to see it in Auckland as its more humid, or early morning with cool air (I've also seen lots of ag planes like Crescos and Air Tractors with vortices). I think it is more prevalent on the C-130 (and maybe Orion) as they have very broad blades so probably induce a greater pressure drop.
BTW Hercules and Orions don't have "max revs". The prop runs at a constant 1020 RPM (+- a percent or two) through all the flight range. There is no propeller pitch lever. The only other setting is Low Speed Ground Idle, which can be set on the ground for each engine, for noise abatement and fuel saving. This drops rpm to about 700 RPM from memory.

[chopper_nut]

Yeah I was thinking about the pressure differential thing today but you're right, you do see it on Crescos a bit.