Addendum,
Prop diameter has nothing to do with aircraft top speed either....the C130
or maybe the Constellation are examples of airplanes with propellers in the
20 foot diameter range, and they go 300 mph easily. Or just look at the
fighters of WWII, huge diameters going 400mph plus.
>I am not sure why people think three blades are less efficient. Like
>everything in aircraft design propeller selection is a compromise. The most
>important feature is probably that the propeller is well matched. The blade
>size needs to be matched to the engine hp. Large diameter props are more
>noisy and having a large diameter prop may limit the tops speed of the
>aircraft. In my experience a 64" three blade wide chord (130 mm) is a good
>choice on aircraft with the 912S at speeds up or near 160 kts. If you think
>your A/C can go faster it might be advantageous to have a smaller prop but
>at the loss of take off and climb performance.
>
>Jerry
>
> LTS@avnet.co.uk
> http://www.avnet.co.uk/touchdown
>----- Original Message -----
From: Nigel Charles <72016.3721@compuserve.com>
>Subject: Engine selection
>
>
> > Message text written by INTERNET:clevelee@cswebmail.com
> > >
> > In addition to wondering why Europas use 3 blade less efficient (than two
> > blade wood) carbon fibre props, he offered the best advice yet (which has
> > been rattling in the back of my mind) on engine selection: The Europa is
> > an expensive aircraft (from his VW aircraft perspective) and installing
> > anything other than the factory recommended engine will severely
> > deteriorate the resale value of the aircraft.
> > <
> >
> > The loss of efficiency for the 3 bladed prop doesn't seem to be as much as
> > the theory would predict. The main reason for the 3 bladed version is to
> > improve ground clearance - very relevant for the mono wheel. The necessary
> > increase in diameter for a 2 bladed prop would increase the risk of prop
> > strike. It may be practical to look at 2 bladed props with the tri-gear.
> >
> > Nigel Charles
>
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