X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Tue, 01 Jul 2014 07:50:32 -0400 Message-ID: X-Original-Return-Path: Received: from nm13-vm5.bullet.mail.ne1.yahoo.com ([98.138.91.235] verified) by logan.com (CommuniGate Pro SMTP 6.0.9e) with ESMTPS id 6958379 for lml@lancaironline.net; Mon, 30 Jun 2014 19:34:32 -0400 Received-SPF: pass receiver=logan.com; client-ip=98.138.91.235; envelope-from=kyrilian_av@yahoo.com Received: from [98.138.101.132] by nm13.bullet.mail.ne1.yahoo.com with NNFMP; 30 Jun 2014 23:33:56 -0000 Received: from [98.138.84.43] by tm20.bullet.mail.ne1.yahoo.com with NNFMP; 30 Jun 2014 23:33:56 -0000 Received: from [127.0.0.1] by smtp111.mail.ne1.yahoo.com with NNFMP; 30 Jun 2014 23:33:56 -0000 X-Yahoo-Newman-Id: 501521.8504.bm@smtp111.mail.ne1.yahoo.com X-Yahoo-Newman-Property: ymail-3 X-YMail-OSG: AdFSDVIVM1nXxYcdRMiGf1y18CqWTPfHcfWaN2rAiVny53k mTvVhNNMVuF1J7J6cBMTJ8BeXS1bU8fGYQ2yI4KJjpbtZhD5n2FTJVw2qxyr RgRLGRz_I5OZw9R__BL_CP865NYWrcZ9dBax34rdTWBQi1FHz2aJ4z4zabnN CeOkL_MsbncnYMEpZabYTODj7qxu5hl.9xzFLJnCOFnDKOZ16G1JD9iR9qIs CDC83qMTrED0nxpMoXd2sL8LIjl4IJKTSaZdhYHknUgCrIfWR5xP9_6MjcAI TBrs3.EJ5uljp5FGVyfKIP9Y4xhm42BUOKrMicPVDgoD0TEW6xvnACuIEuw5 N8dBvV83F2ROicMY_43ZZxxPS8KZBWwHbiV1Y9XEJVkOG4pt6gtxS4aTZWUG 18iT2HaRSa_QkHMQzRnq_SeKqhaOKGTcuUo7Fdbn9ZoVhwNVMjIPagu8QWIa vYFvITdI09J2h0FHM_79_Lk13tMA8aHp8p5X.t.GdJqQMVkIdxwpvgfUSqu8 02pDgrR.lP7XjnEwi1QAZDdtnWLDGIE.aNi4- X-Yahoo-SMTP: mQCJX7qswBDY8ocVKU5pgYmL3O_ezrCW X-Rocket-Received: from [192.168.1.77] (kyrilian_av@107.204.97.190 with xymcookie [216.39.61.254]) by smtp111.mail.ne1.yahoo.com with SMTP; 30 Jun 2014 16:33:56 -0700 PDT References: In-Reply-To: Mime-Version: 1.0 (1.0) Content-Type: multipart/alternative; boundary=Apple-Mail-6575B717-B58A-482A-BAC2-2F3635771BFC X-Original-Message-Id: Content-Transfer-Encoding: 7bit X-Mailer: iPad Mail (11D201) From: Kyrilian Dyer Subject: Re: [LML] Re: Two-blade or three-blade prop for I-550 X-Original-Date: Mon, 30 Jun 2014 19:33:52 -0400 X-Original-To: Lancair Mailing List --Apple-Mail-6575B717-B58A-482A-BAC2-2F3635771BFC Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Rob, I'd be careful about drawing conclusions from the Hartzell plots. I've spoke= n with Les Doud too and got the impression that the three blade Hartzell is m= ore efficient not because it's three blade, but because the design is newer a= nd thus benefits from improved analysis, manufacturing, etc. Performance als= o depends on the power and speed of the airplane. Constant speed props are b= etter over a range of speeds and powers than fixed pitch, but they're still o= ptimized around a design point. I may be all wet, but thought the three blad= e scimitar was designed for the Legacy (speed and power) while the two blade= is an older design not specifically optimized for the Legacy/IO-550. Where M= T's various offerings fit within this range is a whole separate set of varia= bles. Les, please correct me if I'm wrong on any of this. - Kyrilian Sent from my iPad > On Jun 30, 2014, at 10:39 AM, "Stevens Family" w= rote: >=20 > I am interested in this subject, because I purchased a partly built kit so= me years ago, (which I am still building!) which came with an MT 3 bladed co= nstant speed prop. In my conversation with a builder in South Australia rece= ntly, he mentioned that he had swapped out his 3 Blade MT prop for a 2 blade= prop, and increase his cruise speed by 7 knots. (Can=E2=80=99t recall if th= at was 7 Kts indicated, or 7 Kts TAS.) Not sure how this fits with the graph= s which indicate the 3 blades are more efficient! It was my understanding th= at because a 3 bladed prop generates 3 tip vortices against only two on a 2 b= laded prop, it is less efficient. > =20 > =20 > Rob Stevens > Perth, Western Australia. > =20 > =20 > From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of Cha= rles Brown > Sent: Monday, 30 June 2014 7:38 PM > To: Lancair Mailing List > Subject: [LML] Re: Two-blade or three-blade prop for I-550 > =20 > I've enclosed the spreadsheet provided to me by Les Doud of Hartzell. In 2= 009 his phone number was Phone: 937-778-4262 . He believes that the 3-blade= is more effiicient than the two blade even in cruise. I have a hard time b= elieving that, and my airplane with 3 blades has not lived up to the prototy= pe Legacy's performance with the 2-blade as documented in the CAFE report; a= nd the 3-blade is heavier and more expensive to buy and overhaul. Of course= , my airplane is probably not as clean as the prototype. > =20 > But the 3-blade prop sure looks cool.=20 > =20 --Apple-Mail-6575B717-B58A-482A-BAC2-2F3635771BFC Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable
Rob,
I'd be careful about drawing conclusions from the Hartzell plots. I've sp= oken with Les Doud too and got the impression that the three blade Hartzell i= s more efficient not because it's three blade, but because the design is new= er and thus benefits from improved analysis, manufacturing, etc. Performance= also depends on the power and speed of the airplane. Constant speed props a= re better over a range of speeds and powers than fixed pitch, but they're st= ill optimized around a design point. I may be all wet, but thought the three= blade scimitar was designed for the Legacy (speed and power) while the two b= lade is an older design not specifically optimized for the Legacy/IO-550. Wh= ere MT's various offerings fit within this range is a whole separate set of v= ariables.
Les, please correct me if I'm wrong on any of this.
- Kyrilian

Sent from my iPad

On Jun 30, 2014, at 1= 0:39 AM, "Stevens Family" <st= evens5@swiftdsl.com.au> wrote:

I am interested in this subject, because I= purchased a partly built kit some years ago, (which I am still building!) w= hich came with an MT 3 bladed constant speed prop. In my conversation with a= builder in South Australia recently, he mentioned that he had swapped out h= is 3 Blade MT prop for a 2 blade prop, and increase his cruise speed by 7 kn= ots. (Can=E2=80=99t recall if that was 7 Kts indicated, or 7 Kts TAS.) Not s= ure how this fits with the graphs which indicate the 3 blades are more effic= ient! It was my understanding that because a 3 bladed prop generates 3 tip v= ortices against only two on a 2 bladed prop, it is less efficient.

 

 

Rob Stevens

Perth, W= estern Australia.

 

 

= From: Lanc= air Mailing List [mailto:lml@lancai= ronline.net] On Behalf Of Charles Brown
Sent: Monday, 3= 0 June 2014 7:38 PM
To: Lancair Mailing List
Subject: [L= ML] Re: Two-blade or three-blade prop for I-550

<= /div>

 

I've enclosed the spreadsheet provided to me by Les Doud of Hartzell.  = ;In 2009 his phone number was Phone: 937-778-4262 = ;.  He believes that the 3-blade is more effiicient than the two blade e= ven in cruise.  I have a hard time believing that, and my airplane with= 3 blades has not lived up to the prototype Legacy's performance with the 2-= blade as documented in the CAFE report; and the 3-blade is heavier and more e= xpensive to buy and overhaul.  Of course, my airplane is probably not a= s clean as the prototype.

 

But the 3-blade prop su= re looks cool. 

&n= bsp;

= --Apple-Mail-6575B717-B58A-482A-BAC2-2F3635771BFC--