Ceiling effect (in stead of ground effect)

[welliewanger]

An aerodynamic conundrum has struck me:

OK, I'm bored down route and I've bought an RC helicopter to while away the hours until the boss decides he wants to go home. As I fly it over the coffee table and bed in my hotel room there's a marked difference in ground effect.

The strange thing is that as it gets closer to the ceiling it also seems to get more lift there. Is there some sort of "ceiling effect" or am I just cr:mad:p and this is just caused by the same things as table leg effect, chair effect, lamp effect and wall effect? :ouch:

[rudderrudderrat]

Hi welliewanger,

I've seen the same Bernoulli effect is in a science museum, where a disc of plywood is sucked onto the ceiling over the spot where a stream of air is flowing from the ceiling.

The air flow down wash from the blades has to be replaced with an air flow onto the top. Near the ceiling, this replacement airflow is squeezed between the "disc" of your helicopter blades and the ceiling, so you get a drop in pressure over the top of the blades.

[Herod]

So when we get near to the big blue dome that covers the earth, we use less fuel?

[4dogs]

yep,

The ceiling causes a beneficial change in inflow angle which leads to less pitch required, hence less drag and less power required compared to free air. :cool:

Stay Alive...