Return-Path: Received: from imf22aec.mail.bellsouth.net ([205.152.59.70] verified) by logan.com (CommuniGate Pro SMTP 4.2b6) with ESMTP id 230145 for flyrotary@lancaironline.net; Mon, 28 Jun 2004 22:39:58 -0400 Received: from bellsouth.net ([209.214.146.236]) by imf22aec.mail.bellsouth.net (InterMail vM.5.01.06.08 201-253-122-130-108-20031117) with ESMTP id <20040629023922.KSPN1779.imf22aec.mail.bellsouth.net@bellsouth.net> for ; Mon, 28 Jun 2004 22:39:22 -0400 Message-ID: <40E0D658.1040908@bellsouth.net> Date: Mon, 28 Jun 2004 21:39:20 -0500 From: Charlie England User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.4) Gecko/20030624 Netscape/7.1 (ax) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Rotary motors in aircraft Subject: Re: [FlyRotary] Re: Static port location References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Bill, This is really a long shot, but I can remember some reference to a discrepancy in different versions of the plans on which bulkhead to measure from to install the port. Have you called Van's to confirm the location? FWIW, my 1st -4 with flush ports was 10kts slow & 100ft low at cruise speeds until I glued the pop rivet heads over the ports. (Thanks to Kevin Horton on the RV-list.) After the pop installation, it read correctly. Charlie Michael McGee wrote: > 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 >