Return-Path: Received: from atlantic.mail.pas.earthlink.net ([207.217.120.179] verified) by logan.com (CommuniGate Pro SMTP 4.2b6) with ESMTP id 227834 for flyrotary@lancaironline.net; Sat, 26 Jun 2004 20:38:10 -0400 Received: from ip216-26-75-242.dsl.du.teleport.com ([216.26.75.242] helo=michaelm1.teleport.com) by atlantic.mail.pas.earthlink.net with esmtp (Exim 3.33 #1) id 1BeNfv-0000P7-00 for flyrotary@lancaironline.net; Sat, 26 Jun 2004 17:37:39 -0700 Message-Id: <6.1.1.1.0.20040626172211.02324ec0@mail.teleport.com> X-Sender: jmpcrftr@mail.teleport.com X-Mailer: QUALCOMM Windows Eudora Version 6.1.1.1 Date: Sat, 26 Jun 2004 17:26:59 -0700 To: "Rotary motors in aircraft" From: Michael McGee Subject: Re: [FlyRotary] Re: Static port location In-Reply-To: References: Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="=====================_2304593==.ALT" --=====================_2304593==.ALT Content-Type: text/plain; charset="us-ascii"; format=flowed At 13:12 2004-06-26, you wrote: > > ========================== >This version reduced the altimeter error to 50-70 ft high and the >indicated to around 7 KTs too high. > >Not sure what to try for the next version. > >Bill Eslick >============================= >I'm surprised your ASI is that far off Bill. I'm using the same pop >rivet static ports (one each side) and the ASI has been accurate to within >2 mph or less at all speeds I've checked. > >Tracy >============================== >Tracy, > >I am very sure the problem is static, since the altimeter reads high and >two ASIs read exactly the same (Dynon and round-dial). > >Since I have already plumbed in a static probe (removable), I will >continue to investigate probe shapes until I get a winner. > >Bill You guys are comparing an RV-4 with an RV-6 (I know, you knew that). The -6 is known to have some flow separation aft of the bulkhead where the angle changes along the side. Bill, throw some yarn tufts in a grid on the side around the static port and forward past the bulkhead where the angle changes and go get some air to air pics. You should see a difference in the air flow patterns. This may help you pick a better location for the static port. Mike McGee, RV-4 N996RV, O320-E2G, Hillsboro, OR 13B in gestation mode, RD-1C, EC-2 --=====================_2304593==.ALT Content-Type: text/html; charset="us-ascii" At 13:12 2004-06-26, you wrote:

==========================
This version reduced the altimeter error to 50-70 ft high and the indicated to around 7 KTs too high.

Not sure what to try for the next version.

Bill Eslick
=============================
I'm surprised your ASI is that far off Bill. I'm using the same pop rivet static ports (one each side) and the ASI has been accurate to within 2 mph or less at all speeds I've checked.

Tracy
==============================
Tracy,

I am very sure the problem is static, since the altimeter reads high and two ASIs read exactly the same (Dynon and round-dial).

Since I have already plumbed in a static probe (removable), I will continue to investigate probe shapes until I get a winner.

Bill

You guys are comparing an RV-4 with an RV-6 (I know, you knew that). The -6 is known to have some flow separation aft of the bulkhead where the angle changes along the side.

Bill, throw some yarn tufts in a grid on the side around the static port and forward past the bulkhead where the angle changes and go get some air to air pics. You should see a difference in the air flow patterns. This may help you pick a better location for the static port.

Mike McGee, RV-4 N996RV, O320-E2G, Hillsboro, OR
13B in gestation mode, RD-1C, EC-2 --=====================_2304593==.ALT--