Return-Path: Received: from [65.54.169.84] (HELO hotmail.com) by logan.com (CommuniGate Pro SMTP 4.2b2) with ESMTP id 3208149 for flyrotary@lancaironline.net; Thu, 06 May 2004 00:16:52 -0400 Received: from mail pickup service by hotmail.com with Microsoft SMTPSVC; Wed, 5 May 2004 21:16:48 -0700 Received: from 4.174.2.185 by bay3-dav54.adinternal.hotmail.com with DAV; Thu, 06 May 2004 04:16:48 +0000 X-Originating-IP: [4.174.2.185] X-Originating-Email: [lors01@msn.com] X-Sender: lors01@msn.com From: "Tracy Crook" To: "Rotary motors in aircraft" Subject: Re: [FlyRotary] Re: surging / rough idle Date: Thu, 6 May 2004 00:16:48 -0400 MIME-Version: 1.0 X-Mailer: MSN Explorer 7.02.0011.2700 Content-Type: multipart/alternative; boundary="----=_NextPart_001_0000_01C432FF.6BD3D2F0" Message-ID: X-OriginalArrivalTime: 06 May 2004 04:16:48.0879 (UTC) FILETIME=[F366D7F0:01C43320] ------=_NextPart_001_0000_01C432FF.6BD3D2F0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable ----- Original Message ----- From: Russell Duffy Sent: Wednesday, May 05, 2004 7:54 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: surging / rough idle 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 calculation= s 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 y= ou'll need a whole lot more flow rate to deliver the fuel at 10000 than y= ou would at 2000. =20 Now, before anyone says it, I know that Tracy's using those wimpy injecto= rs 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) =20 Rusty, were'd you come up with this theory? True, It takes the same am= ount of fuel to make X horsepower regardless of rpm. The injector does= n't fire as often at low rpm BUT, it stays open for a longer time (assumi= ng the engine is making the same power). It all comes out the same in te= rms of flow rate requirement of the injector. Tracy ------=_NextPart_001_0000_01C432FF.6BD3D2F0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
 
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----- Original Message -----
From: Russell Duffy
Sent: Wednes= day, May 05, 2004 7:54 PM
To: Rotary motors in aircraft
Subj= ect: [FlyRotary] Re: surging / rough idle
 

1.  Do not use injectors th= at 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 co= uld find.  In each case, these calculations are made without ever as= king 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, b= ut you'll need a whole lot more flow rate to deliver the fuel at 100= 00 than you would at 2000.  
 
Now, = before anyone says it, I know that Tracy's using those wimpy injectors wi= th his current system, making 200+ HP at 7000+ rpm, and isn't having any = problems, so clearly they're big enough.   I really hate i= t when he does that :-)
 
<= FONT size=3D2>Rusty (pro= p and bolts arriving tomorrow)
 
  &= nbsp;
Rusty, were'd you come up with this theory?  &= nbsp;True,  It takes the same amount of fuel  to make X horsepo= wer regardless of rpm.   The injector doesn't fire as often at = low rpm BUT, it stays open for a longer time (assuming the engine is maki= ng the same power).  It all comes out the same in terms of flow rate= requirement of the injector.
= Tracy


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