Return-Path: Sender: "Marvin Kaye" To: lml@lancaironline.net Date: Fri, 04 Mar 2005 01:39:27 -0500 Message-ID: X-Original-Return-Path: Received: from [24.25.9.102] (HELO ms-smtp-03-eri0.southeast.rr.com) by logan.com (CommuniGate Pro SMTP 4.3c2) with ESMTP id 769563 for lml@lancaironline.net; Thu, 03 Mar 2005 23:56:42 -0500 Received-SPF: none receiver=logan.com; client-ip=24.25.9.102; envelope-from=hapgoodm94@alum.darden.edu Received: from HP780N (cpe-065-184-084-150.nc.rr.com [65.184.84.150]) by ms-smtp-03-eri0.southeast.rr.com (8.12.10/8.12.7) with SMTP id j244ttkd010384 for ; Thu, 3 Mar 2005 23:55:56 -0500 (EST) From: "Matt Hapgood" X-Original-To: "Lancair Mailing List" Subject: RE: [LML] Re: FADEC Rough idle explanation X-Original-Date: Thu, 3 Mar 2005 23:55:57 -0500 X-Original-Message-ID: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_008C_01C5204C.8B6A4CD0" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook IMO, Build 9.0.2416 (9.0.2910.0) Importance: Normal X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 In-reply-to: X-Virus-Scanned: Symantec AntiVirus Scan Engine This is a multi-part message in MIME format. ------=_NextPart_000_008C_01C5204C.8B6A4CD0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Walter, You said that "[you] think that a good pilot always knows how much fuel he has." I respectfully disagree and I think YOU are on the slippery slope. I think a that a good pilot realizes that he DOESN'T know how much fuel he has, that he MAY have less than he thinks, and therefore plans conservatively. It's the pilot who thinks he has better information than he really does that is more likely to get dead than the conservative pilot. In fact, I'm not sure I'd feel comfortable flying with someone who thinks they have more accuracy in their remaining fuel than than they probably do. Knowing how much fuel you have in flight requires knowing TWO things: 1) Burn rate, and 2) Starting usable fuel amount (and knowing how much fuel a specific flight will require adds in many more variables). Unless I have TOPPED my tanks on a completely LEVEL tarmac, even perfectly accurate fuel flow doesn't really do much for me. Because the bigger issue is "How much fuel did I have to start with" (does Tony D. come to mind?)? And here's the meat of the issue and where I think we really disagree: Measuring fuel flow to +/- .2 GPH doesn't do squat. 5 hours in the air doesn't even equal a gallon. It would be a minor miracle if you could look in your tanks, sitting on an average tarmac, and be within even 2 gallons of accuracy. And if you think your fuel flow is +/- 1%, under the range of conditions in which you fly, then I certainly don't want to fly with you. So, how accurate are YOU trying to be with fuel fuel flow and remaining fuel? Go ahead and measure with a micrometer and cut with a hatchet. I won't hold the piece of wood. And I CERTAINLY didn't say I don't CARE about how much fuel I have or how much I burn (please reread my post). I am just realistic in recognizing that I don't have perfect information, so I'll be conservative. So I'll stick with my comment, which was: "I personally don't really care whether I burn 8 GPH or 9 GPH in cruise. I'm not going to fuel plan that precisely. I can't. I don't always know whether I will fly at 6,000' or 12,000' and that makes a WHOLE lot larger difference in fuel planning than leaning. And just as in the car, I'd land and fuel up if I got lower on fuel than expected on a trip." Maybe you turbo guys are different - no matter what altitude you fly you maintain the same cruise power setting. It's just one number to remember. But that's not the case for us normally aspirated guys. My fuel flows vary significantly on EVERY flight. I don't care to memorize every burn rate at every power setting. I make conservative estimates for flight planning. Don't ask me my Lancairs burn rate - unless you just want a rough estimate, and I won't ask what the actual gas mileage of your SUV is (you'll probably reply that you drive a Honda Insight and I'll look really stupid). If you don't want to fly with me, I'm not offended. Happy flying. Matt ------=_NextPart_000_008C_01C5204C.8B6A4CD0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Walter,
 
You=20 said that "[you] = think that a=20 good pilot always knows how much fuel he has."  =
 
I=20 respectfully disagree and I think YOU are on the slippery=20 slope.  I think a that a good pilot realizes that he=20 DOESN'T know how much fuel he has, that he MAY have less than = he=20 thinks, and therefore plans conservatively. 
 
It's=20 the pilot who thinks he has better information than he really does that = is more=20 likely to get dead than the conservative pilot.   In fact, I'm = not=20 sure I'd feel comfortable flying with someone who thinks they have more = accuracy=20 in their remaining fuel than than they probably=20 do. 
 
Knowing how much fuel you have in flight requires knowing TWO = things: 1)=20 Burn rate, and 2) Starting usable fuel amount (and knowing how much fuel = a=20 specific flight will require adds in many more = variables).
 
Unless I have TOPPED my tanks on a = completely=20 LEVEL tarmac, even perfectly accurate fuel flow doesn't really = do much=20 for me.  Because the bigger issue is "How much fuel did I = have to=20 start with" (does Tony D. come to mind?)? =20
 
And here's the meat of the issue and where I = think we=20 really disagree:  Measuring fuel flow to +/- .2 GPH = doesn't do=20 squat.  5 hours in the air doesn't even equal a = gallon.  It would=20 be a minor miracle if you could look in your tanks, sitting = on an=20 average tarmac, and be within even 2 gallons of accuracy.  And if = you think=20 your fuel flow is +/- 1%, under the range of conditions in = which you=20 fly, then I certainly don't want to fly with you.  So, how = accurate=20 are YOU trying to be with fuel fuel flow and remaining=20 fuel?
 
Go ahead and measure with a micrometer and = cut with a=20 hatchet.  I won't hold the piece of wood. =20
 
And I CERTAINLY didn't say I don't CARE = about how=20 much fuel I have or how much I burn (please reread = my post).  I=20 am just realistic in recognizing that I don't have perfect information, = so I'll=20 be conservative. 
 
So I'll = stick with my=20 comment, which was:
 
"I personally don't really = care whether I=20 burn 8 GPH or 9 GPH in cruise.  I'm not going to fuel plan that=20 precisely.  I can't.  I don't always know whether I will fly = at 6,000'=20 or 12,000' and that makes a WHOLE lot larger difference in fuel planning = than=20 leaning.  And just as in the car, I'd land and fuel up if I = got lower=20 on fuel than expected on a = trip."
 
Maybe you turbo guys are different - no = matter what=20 altitude you fly you maintain the same cruise power setting.  It's = just one=20 number to remember.  But that's not the case for us normally = aspirated=20 guys.  My fuel flows vary significantly on EVERY flight.  I = don't care=20 to memorize every burn rate at every power setting.  I make = conservative=20 estimates for flight=20 planning. 
 
Don't ask me my Lancairs burn rate - unless = you just=20 want a rough estimate, and I won't ask what the actual gas mileage of = your SUV=20 is (you'll probably reply that you drive a Honda Insight and I'll = look=20 really = stupid).
 
If you don't want to fly with me, I'm not=20 offended.  Happy=20 flying.

Matt
 
 
 
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