REFLECTOR: fuel tank placards

Mon Jun 2 13:43:35 CDT 2008

Terry,

My experience with owning and operating several types of certified aircraft through the years was that the manufactures marked their fuel tanks for the exact amount of fuel that each tank would hold. The fact that there was a certain amount of unusable fuel left in the tanks was handled in the approved operating manual for the aircraft. I believe that the issue was that the manufactures were just as concerned that you knew how much fuel weight you could add to your aircraft as they were that you knew how much fuel your aircraft could burn before you fell out of the sky. My fuel gauges were marked as to how many lbs of fuel I had on board not in gal I had on-board for my M20E. I always kept a very detailed chart in each aircraft that I have owned and recorded total hours of each flight, total fuel purchased and how much and when engine oil was added. What this allowed me to do was to have a very accurate record of what my normal fuel burn should be. My
 M20E IO360A1A burned 10 gallons per hour for over 10 years. I knew this because I kept good records. What I found was that I used this chart more to determine how much fuel I needed to add for  a given trip than I used the aircraft fuel gauges or even sticking the tanks. My M20E held 26 gal. per side or 52 gal total and I never liked to fly more that 4 hours per leg on long cross countries which meant that I also used 10 gal as my minimum safe fuel. I can't remember what the POM said the unusable fuel was for my Mooney but I think it was around 2 gal per side or 4 gal total. I plan to use this same practice to mark my tanks when I get to the point that I am calibrating my fuel system. Your system will be up to you, but the main thing is make sure that you operating manual documents what you know to be true for your specific aircraft. Remember you may want to sell it some day.

Andy Ellzey
XLRG still building

----- Original Message ----
From: Terry Miles <terrence_miles at hotmail.com>
To: scott at tnstaafl.net; Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
Sent: Monday, June 2, 2008 10:03:56 AM
Subject: Re: REFLECTOR: fuel tank placards

Thanks Scott.  My sump is 2.5 I think. (XLRG) I am not near the books.  I do
not see the factory fuel sump low light as fuel mgt tool, it is a imminent
engine failure annunciator (and even then with some limitations).  Like you
I can set my fuel tank quant gauges to report a low quant state.  You know
what I would love, and that is to have and instantaneously reading  "Strake
outlet uncovered" light.  

I agree with you on the 10 gal for day VFR use.  For now my GRT fuel flow
system is wildly out of calibration, but I am working on it.  I also have
the V. Atkinson sight gauges, and capacitance fuel gauges.  The electronic
gauges are quirky until I get in the air.  I am boarding fuel with a
combination of dip sticks, truck readings and sight gauges not electronic
readings at present.

Thanks for your thoughts and experiences on this.  Mac Murfree gave me a
copy of the Cirus Perf chapter and I am trying to come up with some burn
figures from say 10,000 thru a procedure turn to landing, and to those
figures tack on numbers like you have offered about what you guys use out
there.

Scott, 29 gallons usable you said.  I get it.  I agree with that as a
technical number.  Now, let me ask this:  Rather than using the term
"usable" if I were to ask when you felt the fuel delivery became unreliable
due to our gravity flow system and normal maneuvering flight would you stick
with 29 gallons (or nearly that)  Is it reasonable to assume the sump
capacity would allow the strakes to pretty much drain out before the engine
experienced any fuel interruption?  What's your guess?  I am not looking for
hard science here.  

Thanks,
Terry  

-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Scott Derrick
Sent: Sunday, June 01, 2008 9:55 PM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: fuel tank placards

My tanks hold 30 gals each,  I consider 29 usable
with a 4 gallon sump with about 2-3 gallons  usable.

That said I ignore the sump in fuel planning.  I plan 58 gallons full 
and my min VFR reserve is 10 gallons.  If I see that I will be getting 
below 20 I do some real hard calculations to verify I really have that 
much.  Yes I have fuel computer, gauges and site tubes.  It not 
uncommon to be 30 minutes from any airport out here in the west.  And 
that doesn't count pattern time.

I have landed with about 7 gallons on board once.  I thought I would 
have about 12-13,but a stronger than forecast head wind ate up an 
additional 5 gallons.  I was very uncomfortable.  As was my wife as she 
watched me repeatedly acknowledge the low fuel  warning once one of the 
tanks read below 5 gallons. 

Scott

Terry Miles wrote:
> Keith,
> For POH reasons and with the assumption that real life xc fuel planning
> follows what you put in the POH.  Are you considering that all the fuel in
> the main tanks is usable?  I am inclined to say I am at dry tanks with 5
> gals in each wing, but I be happy to see what others use for "usuable"  or
> said another way what is the min fuel you want to see on landing at your
> alternate.
> Thanks for the input,
> Terry
>
> -----Original Message-----
> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
> Behalf Of Keith Hallsten
> Sent: Sunday, June 01, 2008 6:47 PM
> To: 'Velocity Aircraft Owners and Builders list'
> Subject: Re: REFLECTOR: fuel tank placards
>
> Doug,
>
> It's your call, but I would consider all of the sump to be either
"unusable"
> or "emergency reserve" and only consider the capacity of the strake tanks
in
> the capacity labeling.
>
> Keith Hallsten
>
>
> -----Original Message-----
> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
> Behalf Of doug.holub at tx.rr.com
> Sent: Sunday, June 01, 2008 2:30 PM
> To: reflector at tvbf.org
> Subject: REFLECTOR: fuel tank placards, Torx head screws
>
> My left and right fuel tanks hold 25.5 gallons each. My sump holds 5
> gallons, but 2 gallons at the bottom of the sump are not reachable. Do I
> placard my fuel tanks for 25.5 gallons plus half of the usable sump? Or
half
> of the whole sump? Or just the tanks?
>
> I saw an ad in one of the magazines a few months ago for Torx head
stainless
> steel 100 degree flat head screws. I bought some and they work just great.
> I've been taking the cowl off and on a lot the past few months, and they
> never strip out. I've got a Torx head for a small electric screwdriver. 
>
> www.microfaseners.com
>
> They don't call them Torx, they call them "6 Lobe Drive". You'll find them
> under "Socket Screws".
>
> Doug Holub, sprinting to the finish line
>
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