Message-ID: <011e01c1d58b$e91c9720$c36eaccf@OFFICE>
From: "Bill & Sue" <harrelson@erols.com>
To: <lancair.list@olsusa.com>
Cc: <jjjohnson@accesscomm.ca>
References: <20020327062139.AAA17740@pop3.olsusa.com>
Subject: Re: lancair.list V1 #360
Date: Wed, 27 Mar 2002 07:35:41 -0500
MIME-Version: 1.0
Content-Type: text/plain;
	charset="iso-8859-1"
Content-Transfer-Encoding: 7bit
Reply-To: lancair.list@olsusa.com

          <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>>
          <<  Lancair Builders' Mail List  >>
          <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> 
>>
> Bill, I'm a  new-bee on the list..just signed up today. Just wanted to ask
> you about 2 bld verses 3 bld props.. even though the there is an extra
> tip/blade involved wouldn't the fact that the blade length is slightly
> shorter and therefore moving slower creating less noise.. and a better tip
> efficency level than a two blade prop?

Hi Jarrett,
Welcome to the list! Thanks for reminding me, the reduced noise is another
factor. A 3 blade spreads the thrust over 50% more blades so the noise
intensity is slightly less and occurrs at a higher frequency. With a 2 blade
at 2500 rpm  5000 prop tips would pass your ears per minute. With a 3 blade
at the same rpm, it would be7500.
The tips may be marginally more efficient at the slightly slower speed, but
this is overshadowed by the fact that there are 50% more of them. You're
definitely right about the noise but the efficiency prize still goes to the
2 blade.

Bill
harrelson@erols.com
N5ZQ


>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
LML website:   http://members.olsusa.com/mkaye/maillist.html
LML Builders' Bookstore:   http://www.buildersbooks.com/lancair
Please remember that purchases from the Builders' Bookstore
assist with the management of the LML.

Please send your photos and drawings to marvkaye@olsusa.com.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>