X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from cdptpa-omtalb.mail.rr.com ([75.180.132.121] verified) by logan.com (CommuniGate Pro SMTP 5.3.9) with ESMTP id 4499453 for flyrotary@lancaironline.net; Sat, 09 Oct 2010 10:24:17 -0400 Received-SPF: pass receiver=logan.com; client-ip=75.180.132.121; envelope-from=eanderson@carolina.rr.com Return-Path: X-Authority-Analysis: v=1.1 cv=lu/RhtYP0ChAeUxMEPBris12a71TWT5f9yvo3GNwP9w= c=1 sm=0 a=RQi-rca4OukA:10 a=rPkcCx1H5rrOSfN0dPC7kw==:17 a=3oc9M9_CAAAA:8 a=FYN5-xcaAAAA:8 a=DbNbkGwUAF9oud6IKsUA:9 a=5WLU6dys3Of8mN5yszGoqCHevMMA:4 a=wPNLvfGTeEIA:10 a=3vEh8dZAO9sA:10 a=U8Ie8EnqySEA:10 a=2qkCJkqNJwVomJiR:21 a=tg3WQvCBIZPgO1Pv:21 a=Ia-xEzejAAAA:8 a=1qPubMmJFNjEwcgsxf0A:9 a=3IL6CI2q_5Ev8uzJeqAA:7 a=FzJ8o-d6H3jbbaNe_ujztZLVUgYA:4 a=EzXvWhQp4_cA:10 a=rPkcCx1H5rrOSfN0dPC7kw==:117 X-Cloudmark-Score: 0 X-Originating-IP: 174.110.167.5 Received: from [174.110.167.5] ([174.110.167.5:61617] helo=EdPC) by cdptpa-oedge02.mail.rr.com (envelope-from ) (ecelerity 2.2.3.46 r()) with ESMTP id 54/AA-14228-DEA70BC4; Sat, 09 Oct 2010 14:23:41 +0000 Message-ID: From: "Ed Anderson" To: "Rotary motors in aircraft" References: In-Reply-To: Subject: Re: [FlyRotary] Propeller design. Date: Sat, 9 Oct 2010 10:23:27 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_002F_01CB679C.03010A30" X-Priority: 3 X-MSMail-Priority: Normal Importance: Normal X-Mailer: Microsoft Windows Live Mail 14.0.8117.416 X-MimeOLE: Produced By Microsoft MimeOLE V14.0.8117.416 This is a multi-part message in MIME format. ------=_NextPart_000_002F_01CB679C.03010A30 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Yes, a radially different concept for Prop design. I remember when the = bi-plane picked up something like a 20 MPH increase in speed with Lipps = prop - it had us all drooling to think that perhaps we could gain a 10 = MPH increase with our RV aircraft. Unfortunately, in the one example I = am somewhat familiar with when put on an Rv-6 the outcome was somewhat = disappointing - I think it was a gain of only about 1-2 MPH. Now in all fairness, Paul's admits his design approach is dependent on = somewhat untradiational accuracy in engine HP and drag of the platform = information - which may have been lacking in this first attempt. = However, since there has not been a flood of aircraft with the Lipps = prop, I'm inclined to believe that it has not yet reach the promise that = first seemed likely. While folks can point to the 20 mph increase in the bi plane's = performance, I can't help but wonder if perhaps the original prop on the = bi plane may have been a poor choice whereupon replacing it with the = Lipps (better matched) make the performance gain seem all related to the = Lipps prop rather than replacing what may have been a poor original = choice - but, just spectulation on my part. I really wanted to see the Lipps prop deliver all it initially seemed to = promise, but I can't find any data yet to support its initial promise - = at least on the type platforms and speeds we normally fly. It's the = first really different approach to prop design I've seen since - well, = since the Wright brothers {:>) If anybody has a source for information that indicates my impression is = incorrect regarding its performance on Rv type aircraft (or similar), I = would like to receive it. Thanks Ed From: Lehanover@aol.com=20 Sent: Saturday, October 09, 2010 9:53 AM To: Rotary motors in aircraft=20 Subject: [FlyRotary] Propeller design. http://www.eaa.org/experimenter/articles/2009-02_elippse.asp I sat through a talk by Paul Lipps at Gene Nevada at the alternative = engine seminar put on by Contact Magazine several years ago. He flew in his home built, with his propeller. Its outer blades were the = size of a 12" ruler. Imagine model sail plane wings, or bread knife = blades. He placed split tennis balls on the tips so guests did not stab = themselves on the blades. Later, he helped a guy design new wings for a biplane racer, and those = wings looked just like his propeller=20 blades. It had a 4 bladed Lipps propeller as well.=20 Not mentioned was the low wetted area of the blades would allow greater = span with less drag. The high angle of attack at the root allowed = playing card sized cooling inlets.=20 In the event of failed engine his prop has less than a 3rd of the = frontal area of a conventional prop. Not exactly full feathering, but better than anything else. So, if the blade has less drag for each unit of lift, then you could add = span until you get close to the ground, and then add blade count until = you have accounted for all of the available HP. Then you port the rotary = to get more HP. Warning, looking at a Lipps propeller blade may hurt your = mind...................... http://www.eaa.org/experimenter/articles/2009-02_elippse.asp Lynn E. Hanover ------=_NextPart_000_002F_01CB679C.03010A30 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Yes, a radially different concept for Prop = design.  I=20 remember when the bi-plane picked up something like a 20 MPH increase in = speed=20 with Lipps prop - it had us all drooling to think that perhaps we could = gain a=20 10 MPH increase with our RV aircraft.  Unfortunately, in the one = example I=20 am somewhat familiar with when put on an Rv-6 the outcome was somewhat=20 disappointing - I think it was a gain of only about 1-2 = MPH.
 
Now in all fairness, Paul's admits his design = approach is=20 dependent on somewhat untradiational accuracy in engine HP and drag of = the=20 platform information - which may have been lacking in this first = attempt. =20 However, since there has not been a flood of aircraft with the Lipps = prop, I'm=20 inclined to believe that it has not yet reach the promise that first = seemed=20 likely.
 
While folks can point to the 20 mph increase in the = bi plane's=20 performance, I can't help but wonder if perhaps the original prop on the = bi=20 plane may have been a poor choice whereupon replacing it with the Lipps = (better=20 matched) make the performance gain seem all related to the Lipps prop = rather=20 than replacing what may have been a poor original choice - but, just=20 spectulation on my part.
 
I really wanted to see the Lipps prop deliver all it = initially=20 seemed to promise, but I can't find any data yet to support its initial = promise=20 - at least on the type platforms and speeds we normally fly.  = It=92s the=20 first really different approach to prop design I've seen since - well, = since the=20 Wright brothers {:>)
 
If anybody has a source for information that = indicates my=20 impression is incorrect regarding its performance on Rv type aircraft = (or=20 similar), I would like to receive it.
 
Thanks
 
Ed

From: Lehanover@aol.com
Sent: Saturday, October 09, 2010 9:53 AM
To: Rotary motors in = aircraft
Subject: [FlyRotary] Propeller design.

htt= p://www.eaa.org/experimenter/articles/2009-02_elippse.asp
 
I sat through a talk by Paul Lipps at Gene Nevada at the = alternative engine=20 seminar put on by Contact Magazine several years ago.
 
He flew in his home built, with his propeller. Its outer = blades were=20 the size of a 12" ruler. Imagine model sail plane wings, or bread knife = blades.=20 He placed split tennis balls on the tips so guests did not stab = themselves on=20 the blades.
 
Later, he helped a guy design new wings for a biplane racer, and = those=20 wings looked just like his propeller
blades. It had a 4 bladed Lipps propeller as well.
 
Not mentioned was the low wetted area of the blades would allow = greater=20 span with less drag. The high angle of attack at the root allowed = playing card=20 sized cooling inlets.
 
In the event of failed engine his prop has less than a 3rd of the = frontal=20 area of a conventional prop.
Not exactly full feathering, but better than anything else.
 
So, if the blade has less drag for each unit of lift, then you = could add=20 span until you get close to the ground, and then add blade count until = you have=20 accounted for all of the available HP. Then you port the rotary to get = more=20 HP.
 
Warning, looking at a Lipps propeller blade may hurt your=20 mind......................
 
htt= p://www.eaa.org/experimenter/articles/2009-02_elippse.asp
 
Lynn E. Hanover
 
 
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