X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from imr-da04.mx.aol.com ([205.188.105.146] verified) by logan.com (CommuniGate Pro SMTP 5.4.1) with ESMTP id 5106704 for flyrotary@lancaironline.net; Mon, 29 Aug 2011 00:13:21 -0400 Received-SPF: pass receiver=logan.com; client-ip=205.188.105.146; envelope-from=shipchief@aol.com Received: from mtaout-da06.r1000.mx.aol.com (mtaout-da06.r1000.mx.aol.com [172.29.51.134]) by imr-da04.mx.aol.com (8.14.1/8.14.1) with ESMTP id p7T4CegD002351 for ; Mon, 29 Aug 2011 00:12:40 -0400 Received: from [10.238.225.56] (166.sub-174-254-205.myvzw.com [174.254.205.166]) (using TLSv1 with cipher AES128-SHA (128/128 bits)) (No client certificate requested) by mtaout-da06.r1000.mx.aol.com (MUA/Third Party Client Interface) with ESMTPSA id 3BA1CE0000F1 for ; Mon, 29 Aug 2011 00:12:38 -0400 (EDT) Subject: Re: [FlyRotary] Re: Props References: From: Scott Emery Content-Type: multipart/alternative; boundary=Apple-Mail-1--870975001 X-Mailer: iPhone Mail (8E600) In-Reply-To: Message-Id: <053AD743-CCCA-4A08-BF7F-FC31BD28ADBB@aol.com> Date: Sun, 28 Aug 2011 21:12:27 -0700 To: Rotary motors in aircraft Content-Transfer-Encoding: 7bit Mime-Version: 1.0 (iPhone Mail 8E600) x-aol-global-disposition: G X-AOL-SCOLL-SCORE: 0:2:480528224:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d33864e5b11b6634c X-AOL-IP: 174.254.205.166 --Apple-Mail-1--870975001 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=us-ascii Paul Lipps designs some radical props. He has a convincing argument in favor= of more blades but less diameter. Less dia. Means less torque arm for tip d= rag / blade. More blades : more thrust. Sent from my iPhone On Aug 25, 2011, at 2:45 PM, Dale_R wrote: > I can't speak from direct experience - yet - but the reason I'm planning o= n a Hertzler Silver Bullet is that several people have found that Gary's two= blade had outperformed the Catto they had made for the same application. Fo= r example, Marc Zeitlin found he liked his new Silver Bullet better than the= three blade that he'd had before. >=20 > Problem is, one of those "other factors" is that for any given output, two= blade usually has to be longer than a three blade. Too long on a pusher an= d it gets trimmed automatically on your first high-angle-of-attack landing. >=20 > Dale_R > COZY MkIV #0497 >=20 >=20 > On 8/25/2011 1:53 PM, Tracy wrote: >>=20 >> Most efficient would be 2 blades. other factors may favor more blades = but that's a different question. >>=20 >> Tracy >>=20 >> On Thu, Aug 25, 2011 at 4:25 PM, Samuel Treffinger wrote: >> Hey, what would you recommend? A three or four blade prop? It will be woo= d, so weight isnt such an issue, but which is more efficient given the same p= ower? >> =20 >> Sam >>=20 >=20 >=20 > --=20 > Dale_R > Cozy MKIV #497 --Apple-Mail-1--870975001 Content-Transfer-Encoding: 7bit Content-Type: text/html; charset=utf-8

Paul Lipps designs some radical props. He has a convincing argument in favor of more blades but less diameter. Less dia. Means less torque arm for tip drag / blade. More blades : more thrust.

Sent from my iPhone

On Aug 25, 2011, at 2:45 PM, Dale_R <dale.rog@gmail.com> wrote:

I can't speak from direct experience - yet - but the reason I'm planning on a Hertzler Silver Bullet is that several people have found that Gary's two blade had outperformed the Catto they had made for the same application. For example, Marc Zeitlin found he liked his new Silver Bullet better than the three blade that he'd had before.

Problem is, one of those "other factors" is that for any given output, two blade usually has to be longer than a three blade. Too long on a pusher and it gets trimmed automatically on your first high-angle-of-attack landing.

Dale_R
COZY MkIV #0497

On 8/25/2011 1:53 PM, Tracy wrote:
Most efficient would be 2 blades. other factors may favor more blades but that's a different question.

Tracy

On Thu, Aug 25, 2011 at 4:25 PM, Samuel Treffinger <samuel.treffinger@gmail.com> wrote:

Hey, what would you recommend? A three or four blade prop? It will be wood, so weight isnt such an issue, but which is more efficient given the same power?

Sam
-- 
Dale_R
Cozy MKIV #497

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