Return-Path: <13brv3@bellsouth.net> Received: from imf19aec.mail.bellsouth.net ([205.152.59.67] verified) by logan.com (CommuniGate Pro SMTP 4.2b2) with ESMTP id 3207887 for flyrotary@lancaironline.net; Wed, 05 May 2004 19:53:05 -0400 Received: from rad ([65.0.146.202]) by imf19aec.mail.bellsouth.net (InterMail vM.5.01.06.08 201-253-122-130-108-20031117) with ESMTP id <20040505235303.LIIJ16168.imf19aec.mail.bellsouth.net@rad> for ; Wed, 5 May 2004 19:53:03 -0400 From: "Russell Duffy" <13brv3@bellsouth.net> To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] surging / rough idle Date: Wed, 5 May 2004 18:51:04 -0500 Message-ID: <01e101c432fb$d3c3a150$6001a8c0@rad> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_01E2_01C432D1.EAED9950" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.4510 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1165 Importance: Normal In-Reply-To: This is a multi-part message in MIME format. ------=_NextPart_000_01E2_01C432D1.EAED9950 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit 1. Do not use injectors that are to large. Go to the RC Engineering web site (www.rceng.com) and calculate the size you need based on HP needed and an 80% duty cycle. (225 HP requires 4 injectors of 38 lb each at 80% duty cycle, fuel pressure of 38 PSI, and a BSFC of 0.5) I just spent some time looking at the RC engineering site, as well as the other fuel injector sites I could find. In each case, these calculations are made without ever asking about rpm. I just don't see how they can do that ??? How do they know if my 225 HP would be at 2000 or 10000 rpm? The same amount of fuel will have to be delivered in either case, but you'll need a whole lot more flow rate to deliver the fuel at 10000 than you would at 2000. Now, before anyone says it, I know that Tracy's using those wimpy injectors with his current system, making 200+ HP at 7000+ rpm, and isn't having any problems, so clearly they're big enough. I really hate it when he does that :-) Rusty (prop and bolts arriving tomorrow) ------=_NextPart_000_01E2_01C432D1.EAED9950 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Message

1.  Do not use injectors that are to large.  = Go to the=20 RC Engineering web site (www.rceng.com) and calculate the size you need = based on=20 HP needed and an 80% duty cycle.  (225 HP requires 4 injectors of = 38 lb=20 each at 80% duty cycle, fuel pressure of 38 PSI, and a BSFC of = 0.5)

I just = spent some time=20 looking at the RC engineering site, as well as the other fuel injector = sites I=20 could find.  In each case, these calculations are made without ever = asking=20 about rpm.  I just don't see how they can do that ???  How do = they=20 know if my 225 HP would be at 2000 or 10000 rpm?  The = same amount=20 of fuel will have to be delivered in either case, but you'll need a = whole=20 lot more flow rate to deliver the fuel at 10000 than you would at=20 2000.  
 
Now, = before anyone says=20 it, I know that Tracy's using those wimpy injectors with his current = system,=20 making 200+ HP at 7000+ rpm, and isn't having any problems, so clearly=20 they're big enough.   I really hate it when he does = that=20 :-)
 
Rusty (prop and=20 bolts arriving tomorrow)
 
   =20


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