X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from aspensprings.uwyo.edu ([129.72.10.32] verified) by logan.com (CommuniGate Pro SMTP 5.4c3j) with ESMTPS id 4962754 for flyrotary@lancaironline.net; Sat, 30 Apr 2011 12:34:24 -0400 Received-SPF: none receiver=logan.com; client-ip=129.72.10.32; envelope-from=SBoese@uwyo.edu Received: from ponyexpress-ht2.uwyo.edu (ponyexpress-ht2.uwyo.edu [10.84.60.209]) by aspensprings.uwyo.edu (8.14.4/8.14.4) with ESMTP id p3UGXj7c010178 (version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=FAIL) for ; Sat, 30 Apr 2011 10:33:46 -0600 (MDT) (envelope-from SBoese@uwyo.edu) Received: from ponyexpress-mb5.uwyo.edu ([fe80::9813:248c:2d68:a28b]) by ponyexpress-ht2 ([10.84.60.209]) with mapi; Sat, 30 Apr 2011 10:33:45 -0600 From: "Steven W. Boese" To: Rotary motors in aircraft Date: Sat, 30 Apr 2011 10:33:37 -0600 Subject: RE: [FlyRotary] Re: Intakes old and new Thread-Topic: [FlyRotary] Re: Intakes old and new Thread-Index: AcwHUuwuqvlVnE7OTo6G5OfLhA6VKAAAROfQ Message-ID: References: In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: en-US Content-Type: multipart/alternative; boundary="_000_E1AA3B1AF41D8049B1E3FBD5E2256260088BB24534ponyexpressmb_" MIME-Version: 1.0 --_000_E1AA3B1AF41D8049B1E3FBD5E2256260088BB24534ponyexpressmb_ Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable I meant to say "optimizing" BSFC, not "maximizing". The goal is to make th= e value of BSFC small. Steve From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Beh= alf Of Steven W. Boese Sent: Saturday, April 30, 2011 10:23 AM To: Rotary motors in aircraft Subject: [FlyRotary] Re: Intakes old and new I use much the same cruise technique as Tracy. Starting from a 60 deg F LO= P mixture and throttle setting giving close to the desired airspeed, I adj= ust the mixture to maximize the MPG calculated from the fuel flow and IAS. = This is essentially maximizing BSFC. One thing that should be verified is= that no change in staging takes place during the MPG optimization. With a= well tuned system, the engine doesn't care if staging is occurring, but th= e MPG readout will change with staging at same fuel flow rate. This is ass= uming that the fuel flow rate is based on injector pulse width. If a fuel = flow sensor such as a Floscan unit is used, then staging is of no consequen= ce. Steve Boese RV6A 1986 13B NA RD1A EC2 From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Beh= alf Of Tracy Sent: Saturday, April 30, 2011 9:38 AM To: Rotary motors in aircraft Subject: [FlyRotary] Re: Intakes old and new Everybody has their own technique for cruising. I typically aim to get the= highest reading on the EM2/3 MPG readout along with a reasonable airspeed.= On my RV4 this is usually around 17 - 18" Hg. MP and 130 - 135 IAS / 170 = - 175 TAS at 15,500. This is way less than WOT. Pumping losses are a fa= ctor in efficiency but IMO it is way over rated. There is no question tha= t aero losses at higher speeds more than make up for the pumping loss impro= vement. If pumping losses were that big, cars would get terrible fuel mile= age at 55 mph. Tracy On Sat, Apr 30, 2011 at 10:52 AM, Bill Bradburry > wrote: Ed, I have heard you mention that you seldom fly at max speed. How do you do t= his? Do you fly at WOT but high enough to lower the output and lean for ec= onomy, thus reducing the speed? Do you reduce throttle?? I have been given to understand that the throttle should be at WOT all the = time to reduce "pumping losses". Engine power would then be affected by ot= her means, leaning, altitude, prop speed if you can adjust it??? What is your method? For that matter, what method do others use? Bill B --_000_E1AA3B1AF41D8049B1E3FBD5E2256260088BB24534ponyexpressmb_ Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

I meant to say “optimizi= ng” BSFC, not “maximizing”.  The goal is to make the= value of BSFC small.

 =

Steve

 

From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]= On Behalf Of Steven W. Boese
Sent: Saturday, April 30, 20= 11 10:23 AM
To: Rotary motors in aircraft
Subject: [Fly= Rotary] Re: Intakes old and new

 

I use much the same cruise techniq= ue as Tracy.  Starting from a 60 deg F LOP mixture and  throttle = setting giving close to the desired airspeed, I adjust the mixture to maxim= ize the MPG calculated from the fuel flow and IAS.  This is essentiall= y maximizing BSFC.  One thing that should be verified is that no chang= e in staging takes place during the MPG optimization.  With a well tun= ed system, the engine doesn’t care if staging is occurring, but the M= PG readout will change with staging at same fuel flow rate.  This is a= ssuming that the fuel flow rate is based on injector pulse width.  If = a fuel flow sensor such as a Floscan unit is used, then staging is of no co= nsequence.

 

S= teve Boese

RV6A 1986 13B NA RD1A EC2=

 

&= nbsp;

 

From: Rotary motors in aircraft [mailto= :flyrotary@lancaironline.net] On Behalf Of Tracy
Sent: Sat= urday, April 30, 2011 9:38 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Intakes old and new

 

Everybody has their own technique for cruising.  = I typically aim to get the highest reading on the EM2/3 MPG readout along w= ith a reasonable airspeed.  On my RV4 this is usually around 17 - 18&q= uot; Hg. MP and 130 - 135 IAS / 170 - 175 TAS at 15,500.   This is way= less than WOT.   Pumping losses are a factor in efficiency but IMO it= is way over rated.   There is no question that aero losses at higher = speeds more than make up for the pumping loss improvement.  If pumping= losses were that big, cars would get terrible fuel mileage at 55 mph. = ;

Tracy

On Sat, Apr 30, 201= 1 at 10:52 AM, Bill Bradburry <bbradburry@bellsouth.net> wrote:

Ed,

 

I have heard you mention that you seldom fly at= max speed.  How do you do this?  Do you fly at WOT but high enou= gh to lower the output and lean for economy, thus reducing the speed? = Do you reduce throttle??

 

I have been given to understand that the throttle shoul= d be at WOT all the time to reduce “pumping losses”.  Engi= ne power would then be affected by other means, leaning, altitude, prop spe= ed if you can adjust it???

 

What is your method?  For that matter, what method= do others use?

 

<= p class=3DMsoNormal style=3D'mso-margin-top-alt:auto;mso-margin-bottom-alt:= auto'>Bill B

= --_000_E1AA3B1AF41D8049B1E3FBD5E2256260088BB24534ponyexpressmb_--