X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from wx-out-0506.google.com ([66.249.82.235] verified) by logan.com (CommuniGate Pro SMTP 5.1c.4) with ESMTP id 1414564 for flyrotary@lancaironline.net; Fri, 22 Sep 2006 02:29:41 -0400 Received-SPF: pass receiver=logan.com; client-ip=66.249.82.235; envelope-from=blake.lewis@gmail.com Received: by wx-out-0506.google.com with SMTP id i29so890022wxd for ; Thu, 21 Sep 2006 23:28:55 -0700 (PDT) DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:to:subject:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=mnNX1NErG48q6yHDCpJRBIsmeGq4woS388ak0J1rqGnkAGZu3whHYYAl51NO+jz6Ywpa5ELupGYDFJHpwIASzC+n2Lhxoiw5pZcgUIjq+JN59IVTVGQvcHYBI2Ch5ZfLdSReMpMnP/B94xNgDsGlT4FGKa/QZg725n1I2BQA+XU= Received: by 10.90.100.6 with SMTP id x6mr28429agb; Thu, 21 Sep 2006 23:28:55 -0700 (PDT) Received: by 10.90.82.18 with HTTP; Thu, 21 Sep 2006 23:28:55 -0700 (PDT) Message-ID: Date: Fri, 22 Sep 2006 01:28:55 -0500 From: "Blake Lewis" To: "Rotary motors in aircraft" Subject: Re: [FlyRotary] Re: Fuel Pressure Regulator Vacuum or Boost?? In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline References: I am just learning this stuff. This is my line of thoughts on the subject. The amount of fuel that will flow through the injector during a pulse width, is proportional to the pressure differential across the injector. (Delta Pressure) * (Pulse Time) = constant * Volume Without the "Vacuum Regulator", at Idle when you have a vacuum (less pressure) the Delta Pressure would be bigger, flowing more fuel per pulse time. I guess the computer wants a constant flow rate. The manifold pressure could change significantly during the intake cycle. Cycle time inversely proportional to rpm. The pulse width is proportional to rpm. So, as we need more fuel we have less time to inject it. And during the injection time, whithout the vacuum regulator, the flow rate would change, being less predictable for the computer. I think you would want the injector open over most of the intake cycle to get the best mix. Maybe starting a little late so as not to be flowing fuel during the exhaust overlap. I'll pick 79% for the duty cycle of the injector. Since the rotary's manifold is always in the intake cycle we would want the injector open 79% of the time. Which is also 79% of the intake cycle. In one rotor rotation: close open close open close open 7% 26.33% 7% 26.33% 7% 26.33% But in one shaft rotation it is: close open 21% 79% Is this what you want at full power WOT? Now I understand the desire for staged injectors. At lower rpms you can keep the lower flow injector open longer getting a better mix. -- Blake C. Lewis