Overheating?

[Modena]

Originally Posted by Towmaster

Also a curved blade is more efficient than a blade that is straight from the centre to the shroud. I have a mate that was an engineer for Bell Helicopters told me that.....

So how come helicoptor blades (and airplane props) are straight?

[snakesaway]

Hi all,

Thanks for your thoughts and input, looks like I am just being paranoid which is good I guess. I now really need to test it on a hot day in traffic that is the real test I guess. On the straight curved blade issue, the ebay fan had more blades and was curved the Davies Craig has less and they are straight. Don't really know what it all means but the Davies Craig fan certainly moves significantly more air than the ebay one (funny about that) and even dims the headlights and dash lights when turned on. Hmm may need a new alternator bugger. It will have to be a shinny chrome one more under bonnet bling .

Cheers Andrew

[Krait]

Originally Posted by Modena

So how come helicopter blades (and airplane props) are straight?

Not all are. Depends on the requirement of the particular aircraft. Civil aviation is quite a conservative industry. Have a look at the turbine blades on a late model airliner, they will be generally be curved or sickle shaped.

Compound shapes require the use of hybrid construction using composites combined with exotic materials such as titanium.

Light aircraft such as a Cessna 172 don't see the benefit of exotic engineering so not worth the cost of development and certification.

[Towmaster]

Originally Posted by Krait

Not all are. Depends on the requirement of the particular aircraft. Civil aviation is quite a conservative industry. Have a look at the turbine blades on a late model airliner, they will be generally be curved or sickle shaped.

Compound shapes require the use of hybrid construction using composites combined with exotic materials such as titanium.

Light aircraft such as a Cessna 172 don't see the benefit of exotic engineering so not worth the cost of development and certification.

Yep that's what I was gunna say......... lol

In essence that is what my mate told me..... I just couldn't remember the technical bits just the 'curved blades are more efficient' bit...

[cycleguy55]

Originally Posted by Modena

So how come helicoptor blades (and airplane props) are straight?

Many of the newer turboprops use curved or scimitar blades - apparently higher tip speeds see more benefit from it, which may explain why smaller aircraft (e.g. Cessna 172) are fitted with straight-bladed props.

https://en.wikipedia.org/wiki/Scimitar_propeller