X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Fri, 12 May 2006 17:12:08 -0400 Message-ID: X-Original-Return-Path: Received: from smtpauth07.mail.atl.earthlink.net ([209.86.89.67] verified) by logan.com (CommuniGate Pro SMTP 5.0.9) with ESMTP id 1110647 for lml@lancaironline.net; Fri, 12 May 2006 11:39:12 -0400 Received-SPF: none receiver=logan.com; client-ip=209.86.89.67; envelope-from=rtitsworth@mindspring.com DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; d=mindspring.com; b=f7DhBrgfdSlboRkmSOUNm9L/QJbJlkYm/A7eKVuPl082GzRyrPCbyU3tP+JxW1zc; h=Received:Reply-To:From:To:Subject:Date:MIME-Version:Content-Type:X-Mailer:Thread-Index:In-Reply-To:X-MimeOLE:Message-ID:X-ELNK-Trace:X-Originating-IP; Received: from [68.40.94.44] (helo=RDTVAIO) by smtpauth07.mail.atl.earthlink.net with asmtp (Exim 4.34) id 1FeZil-0006AX-SV for lml@lancaironline.net; Fri, 12 May 2006 11:38:28 -0400 Reply-To: From: "richard titsworth" X-Original-To: "'Lancair Mailing List'" Subject: RE: [LML] Re: Poor Man's Dyno X-Original-Date: Fri, 12 May 2006 11:38:14 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_001A_01C675B8.8E7BFB40" X-Mailer: Microsoft Office Outlook, Build 11.0.5510 Thread-Index: AcZ1vxlILQD3fr5BT86Wz2lt0jS79gAFuvyw In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2869 X-Original-Message-ID: X-ELNK-Trace: b17f11247b2ac8f0a79dc4b33984cbaa0a9da525759e265482c197b01c9b1449516bf396ada939a34e508857176a6fc1350badd9bab72f9c350badd9bab72f9c X-Originating-IP: 68.40.94.44 This is a multi-part message in MIME format. ------=_NextPart_000_001A_01C675B8.8E7BFB40 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Ok, for math geeks, here's a nit-pick point. When doing the poor man's dyno test the propeller slip stream will cause the wing to create some lift (small amount). The amount of lift is of course dependent on slip stream velocity and angle of attach. All is ok so far, as the actual weight is not really a consideration, only the rotational force (i.e. the difference in the right and left scale indications). However, the slip stream has a rotational component to it. Thus, the actual angle of attach on each wing is a bit different. Thus, the lift created by each wing is bit different. Thus, there is an additional rotation (torque) force that is not due to "the engine using the prop to fight against the air" (i.e. the engine HP). Since the left wing will have a higher angle of attach it will create more lift and tend to reduce the force (torque) as measured on the scales. Also the rotational component of the slip stream impacts the tail, which also causes a (small) induced aerodynamic rotational (torque) force. This also is in the direction of lifting the left wing, which reduces the force (torque) as measured on the scales. While these are effects presumed to be insignificant in relative magnitude. They are essentially part of the asymmetric force affects taught during twin (with an engine out) training - with a little editorial liberty. Rick ------=_NextPart_000_001A_01C675B8.8E7BFB40 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

Ok, for math geeks, here’s a = nit-pick point. 

 

When doing the poor man’s = dyno test the propeller slip stream will cause the wing to create some lift (small amount).  The amount of lift is of course dependent on slip stream = velocity and angle of attach.  All is ok so far, as the actual weight is not = really a consideration, only the rotational force (i.e. the difference in the = right and left scale indications).

 

However, the slip stream has a = rotational component to it.  Thus, the actual angle of attach on each wing is = a bit different.  Thus, the lift created by each wing is bit different. =  Thus, there is an additional rotation (torque) force that is not due to = “the engine using the prop to fight against the air” (i.e. the engine = HP).  Since the left wing will have a higher angle of attach it will create more = lift and tend to reduce the force (torque) as measured on the = scales.

 

Also the rotational component of = the slip stream impacts the tail, which also causes a (small) induced aerodynamic = rotational (torque) force.  This also is in the direction of lifting the left = wing, which reduces the force (torque) as measured on the = scales.

 

While these are effects presumed to = be insignificant in relative magnitude. They are essentially part of the = asymmetric force affects taught during twin (with an engine out) training - with a = little editorial liberty.

 

Rick

 

=
------=_NextPart_000_001A_01C675B8.8E7BFB40--