X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Tue, 29 Dec 2009 12:53:37 -0500 Message-ID: X-Original-Return-Path: Received: from smtp-auth-03.mx.pitdc1.expedient.net ([206.210.66.136] verified) by logan.com (CommuniGate Pro SMTP 5.3c4) with ESMTPS id 4043094 for lml@lancaironline.net; Sun, 27 Dec 2009 18:16:16 -0500 Received-SPF: none receiver=logan.com; client-ip=206.210.66.136; envelope-from=rpastusek@htii.com Received: from HTBOB001 (static-72-66-86-7.washdc.fios.verizon.net [72.66.86.7]) by smtp-auth-03.mx.pitdc1.expedient.net (Postfix) with ESMTPA id C92E77C5FF for ; Sun, 27 Dec 2009 18:15:41 -0500 (EST) From: "Robert Pastusek" X-Original-To: "'Lancair Mailing List'" References: In-Reply-To: Subject: RE: [LML] Re: Fuel Planning X-Original-Date: Sun, 27 Dec 2009 18:15:37 -0500 X-Original-Message-ID: <017901ca874a$802f17a0$808d46e0$@com> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_017A_01CA8720.97590FA0" X-Mailer: Microsoft Office Outlook 12.0 Thread-Index: AcqHM1AT5FuI0PsERbGwfPQA4KOA4AAEIEsQ Content-Language: en-us This is a multi-part message in MIME format. ------=_NextPart_000_017A_01CA8720.97590FA0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Gentlemen, =20 I=92d like to weigh in with Grayhawk on the =93when to refuel=94 issue. = I have a TSIO-550 powered Lancair IV-P that has 6+ hours of fuel aboard when = fully filled; more if I slow it down a bit. After 400+ flight hours in the = past 1 =BD years, I am very comfortable with the fuel consumption rate, and the amount remaining at any given time. I installed an Electronics = International MVP-50 engine/aircraft monitoring system, along with EI=92s standard capacitance fuel probes. The probes measure actual fuel in the tanks, = and the MVP-50 separately integrates measured fuel flow over time to = calculate total fuel burned/total fuel remaining. (oth the MVP-50 and Chelton EFIS systems use this latter information to project distance and time to fuel exhaustion, as do other EFIS.)=20 =20 As standard procedure, I check the fuel added to each tank each time I = fill up completely, and compare it to the tank probe-measured fuel remaining. Over time, I have confirmed that on level ground the fuel calibration is accurate within 2 gallons at all fuel amounts for each tank. This is not true in flight, however. The displayed fuel quantity varies only = slightly (estimated at less than 10% for moderate climbs or descents=97using = pitch angles the airplane can sustain for the time needed for the fuel = quantity measurement to stabilize), however even a slight amount of yaw causes = the measured quantity to vary significantly. I can generate fuel = measurements of half to twice what=92s actually in each wing --when they are partially filled--by sustained excessive out of trim conditions in yaw. When the aircraft is returned to a level pitch and a yaw-trimmed position, the = fuel quantity measures within 2 gallons of actual for all amounts=97as on the ground. I tested this extensively during initial flight testing, and possibly could improve it with a re-calibration? I have resisted doing = this because it is well within my allowable tolerance now, and as someone = else on the list pointed out, there=92s always a chance to =93dis-improve=94 = what I now have. =20 The reason I am very confident in my fuel measurement/management system = is that I cross-check the quantity required to refill each tank with the corresponding fuel quantity indicator, and then with the total computed = fuel burn since last fill up. Unlike the quantity probes, the fuel burned calculation performed by the MVP-50 is very easy to re-calibrate, and = over time I have refined it such that it is consistently within 2% of the = actual fuel burned, no matter what the flight conditions or power setting.=20 =20 Both the quantity and totalizer values are alarmed on my MVP-50 to = indicate low fuel in each tank and low total fuel remaining, and I tested this function during flight test as well. The result is that I have two very reliable, independent instrumentation systems to measure fuel burn/fuel remaining, and the ability to check the calibration/accuracy with each fill-up. I also know that I have 6+ hours fuel aboard after fill-up WITH = MY NORMAL OPERATING METHODS. I also alarmed the fuel flow above 45 GPH to indicate a possible fuel leak, but this is a reliable indicator for only some of the failure modes=97still, another useful feature of the MVP-50. =20 I think each pilot should use a system he/she is comfortable with, and dealing very conservatively with fuel and icing will provide a longer = life expectancy! Still, I believe the instrumentation and monitoring systems = now available actually allow us to fly safely without filling the tanks at = every stop=97as I did faithfully 30 years ago=85 Also, if you=92re still = building, I can recommend, without reservation, EI=92s MVP-50 engine/aircraft = monitoring system. It=92s been one of the most reliable and useful instrumentation systems on my airplane=85for this and other functions. =20 Bob ------=_NextPart_000_017A_01CA8720.97590FA0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Gentlemen,

 

I’d like to weigh in with Grayhawk on the = “when to refuel” issue. I have a TSIO-550 powered Lancair IV-P that has 6+ = hours of fuel aboard when fully filled; more if I slow it down a bit. After = 400+ flight hours in the past 1 =BD years, I am very comfortable with the = fuel consumption rate, and the amount remaining at any given time. I installed an = Electronics International MVP-50 engine/aircraft monitoring system, along with = EI’s standard capacitance fuel probes. The probes measure actual fuel in the tanks, = and the MVP-50 separately integrates measured fuel flow over time to calculate = total fuel burned/total fuel remaining. (oth the MVP-50 and Chelton EFIS systems = use this latter information to project distance and time to fuel exhaustion, as do other = EFIS.)

 

As standard procedure, I check the fuel added to each = tank each time I fill up completely, and compare it to the tank probe-measured = fuel remaining. Over time, I have confirmed that on level ground the fuel calibration is accurate within 2 gallons at all fuel amounts for each = tank. This is not true in flight, however. The displayed fuel quantity varies only slightly (estimated at less than 10% for moderate climbs or = descents—using pitch angles the airplane can sustain for the time needed for the fuel = quantity measurement to stabilize), however even a slight amount of yaw causes = the measured quantity to vary significantly. I can generate fuel measurements of half = to twice what’s actually in each wing --when they are partially = filled--by sustained excessive out of trim conditions in yaw. When the aircraft is returned = to a level pitch and a yaw-trimmed position, the fuel quantity measures = within 2 gallons of actual for all amounts—as on the ground. I tested this = extensively during initial flight testing, and possibly could improve it with a re-calibration? I have resisted doing this because it is well within my = allowable tolerance now, and as someone else on the list pointed out, = there’s always a chance to “dis-improve” what I now = have.

 

The reason I am very confident in my fuel = measurement/management system is that I cross-check the quantity required to refill each tank = with the corresponding fuel quantity indicator, and then with the total computed = fuel burn since last fill up. Unlike the quantity probes, the fuel burned calculation performed by the MVP-50 is very easy to re-calibrate, and = over time I have refined it such that it is consistently within 2% of the actual = fuel burned, no matter what the flight conditions or power setting. =

 

Both the quantity and totalizer values are alarmed on my = MVP-50 to indicate low fuel in each tank and low total fuel remaining, and I = tested this function during flight test as well. The result is that I have two very = reliable, independent instrumentation systems to measure fuel burn/fuel remaining, = and the ability to check the calibration/accuracy with each fill-up. I also know = that I have 6+ hours fuel aboard after fill-up WITH MY NORMAL OPERATING = METHODS. I also alarmed the fuel flow above 45 GPH to indicate a possible fuel = leak, but this is a reliable indicator for only some of the failure = modes—still, another useful feature of the MVP-50.

 

I think each pilot should use a system he/she is = comfortable with, and dealing very conservatively with fuel and icing will provide a = longer life expectancy! Still, I believe the instrumentation and monitoring = systems now available actually allow us to fly safely without filling the tanks = at every stop—as I did faithfully 30 years ago…=A0 Also, if = you’re still building, I can recommend, without reservation, EI’s MVP-50 engine/aircraft monitoring system. It’s been one of the most = reliable and useful instrumentation systems on my airplane…for this and other functions.

 

Bob

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