I completely disagree. I would never buy a four blade fan. Five
blade fans move MUCH more air. I've replaced all the 4 blade fans in
my house with 5 blade fans and the results are much better.
Go for the biggest diameter you can, too. Makes a difference.
You proved the other poster's point. Many light civil aircraft have
two bladed props. Light and low powered WWI had two. High performance
fighters and heavy bombers from WWII have four blades. More blades
move more air.
fixed top posting
> You proved the other poster's point. Many light civil aircraft have
> two bladed props. Light and low powered WWI had two. High performance
> fighters and heavy bombers from WWII have four blades. More blades
> move more air.
Actually he didn't. The number of blades have nothing to do with
efficiency. The most efficient propeller is actually one blade. Multi
blade designs are used for other reasons.
Still goes back to total design, not just numbers. Look at the blades on
the huge windmills used to generate electric. Usually three long narrow
As for aircraft, one reason to use the three or four blades over just two is
ground clearance. When the tail comes up, you don't want the blade to hit.
Here's my response from an earlier thread regarding ceiling fan
Disclaimer: I don't work for a fan company so none of this is a
testmonial or sales pitch. It's just info...
Here's some quick info on ceilings fans, both of which include some
verbage on blades angles.
Stolen without permission from
*** Begin Included Text ***
"Don't let your ceiling fan leave you hot under the collar... Just
because a ceiling fan moves air doesn't mean it moves enough air to
keep you comfortable. The blade pitch (or angle) determines how much
air is moved when the fan is on. Some fans have blades with a very
shallow pitch because their motors are not powerful enough to handle
the extra demand made by steeper blade pitches. Casablanca fans use a
motor which is engineered to be more than powerful enough to operate
fan blades with a full 14 degree pitch. So you always get the right
amount of air to keep cool and comfortable."
*** End Included text ***
Interesting fact: The first 3 fans listed under the model section at
that site are 3, 4 and 5 blade fans. The 3 blade has an air flow
of 4 out 5, while the 4 & 5 bladers are rated 5 out of 5. Casablanca
claims 5 is the best, but I don't know if that's their standard or an
Bottom line: If a fan isn't bragging about it's blade angle and motor
quality as selling points, that may mean it's not as steep or strong
as one would like. My guess is that no one is putting a motor that
handle a 14 degree pitch on a fan with an 8 degree pitch, if you know
what I mean.
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.