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AeroElectric-List Digest: 41 Msgs - 08/13/09

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Speedy11(at)aol.com
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Posted: Fri Aug 14, 2009 9:06 am Post subject: AeroElectric-List Digest: 41 Msgs - 08/13/09

I appreciate the piloting technique advice.  I've been using similar  techniques since '73.

 I always strive to know my fuel amount before takeoff and monitor  consumption during flight.  I know how to do those things.

  

 What I'm searching for is accurate fuel sensors rather than advice on  piloting.

 I don't need measurement to 1/10 gallon, but measurement to within 1 gallon  should be obtainable.

  

 Ernest, there is nothing wrong with going to FAA minimums.  I do it  frequently during instrument approaches.  The FAA fuel minimums are  designed to provide a necessary buffer for additional flight time.  There  is nothing wrong with flying to FAA minimums.  If your logic of never  approaching the FAA minimums were adhered to, many aircraft would not be able to  land out of an instrument approach.  Flying to the FAA fuel minimums is  quite acceptable - providing a suitable backup plan is in effect.  By the  way, who wrote the "rules" you quoted?  If they are your rules, then they  are opinion for the rest of us - rules for you.

  

 I will continue to pursue accuracy in fuel measurement - perhaps in  futility.  As I study the Princeton sensors and the AF-3400, I cannot  logically see why they would not work as designed.  So, maybe my  installation is the problem.  I'll check wiring again.

  

 Stan Sutterfield

 Do not archive

  

  

 My EI FL-2CA fuel gauges come with the ability to select the "rate  of

update" which solves one of the problems, but isn't the REAL  problem

that one shouldn't be playing down in the "low fuel minefield" any  way?

Why worry about how to tell exactly when you're going to run out  of

fuel?  I'd rather have really accurate gauges down to a quarter  tank,

and then who cares, it's time to fill up.



An accurate stick with  marks on it, and confidence in fuel consumption

rates, IMHO, are much more  important than measuring fuel quantities near

empty, unless you have no  access at all to a physical measurement of

fuel levels.

  	  Quote: 	
		  Maybe    that is one more thing Heinlein should have added to his list of 

things a    man should know how to do:  tell how much fuel is in a tank by 

how    wildly the indicator is bouncing.



First rule:  If you are so    worried about the fuel remaining that you 

need to know within a tenth of a    gallon, you need to be punching the 

"nearest" button on your GPS...not    stretching your glide to the destination.



Second rule:  If the    guage is bouncing all over the place, you either 

have fuel or the guage is    broken.  One of the first things we learned in 

my high-school    chemistry class was how to interpret a bouncing arm on a 

triple-beam    scale.  If it bounced equally to both side of the center 

mark, then    it was balanced.  With the fuel level indicator, if it is 

bouncing    around the top, proceed.  If it bounces around the bottom, 

punch    "nearest" of call the fuel truck before launching.



Third rule:     The FAA minimums are minimums, not a GOAL. 	


 

  

 

  [quote][b]

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Speedy11(at)aol.com
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Posted: Fri Aug 14, 2009 10:23 am Post subject: AeroElectric-List Digest: 41 Msgs - 08/13/09

Geek, Nerd, or Ernest,

 I'm surprised you are willing to accept the poor excuse for fuel  measurement we've had for the past 60 years.  With your skills, I would  have expected you to jump on this challenge and solve it.

 There must be a solution.

 Stan

 Do not archive

  	  Quote: 	
		  No    resistance, Paul.  It is just that I don't think they can be had for    

reasonable dollars and effort.  You're trying to hit a moving    target.  

Literally, the fuel is jumping around all over the    place.  You can have 

mechanics integrate over time to come up with an    average level.  You can 

have electronics integrate for you, or you    can do the integration on 

your own.



Every design is a different    moving target, and every gauge will have a 

slightly different    calibration.  Install a simple gauge, then get to 

know how it behaves    and you will be better off. 	


 

  

 

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echristley(at)nc.rr.com
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Posted: Fri Aug 14, 2009 11:42 am Post subject: AeroElectric-List Digest: 41 Msgs - 08/13/09

Speedy11(at)aol.com wrote:

 	  Quote: 	
		   Geek, Nerd, or Ernest,

 I'm surprised you are willing to accept the poor excuse for fuel 

 measurement we've had for the past 60 years.  With your skills, I 

 would have expected you to jump on this challenge and solve it.

 There must be a solution.

 Stan

But, I have solved it.  I installed a capacitive fuel gauge which Jim 
	


Weir designed and published in KitPlanes.

I have a sight gauge as backup.  It has a 3/8 opening, so I don't have 

to worry about foaming causing inaccuracies.

The final element of the solution is integrating the dial's reading with 

my mind.



Before we can design a solution, be have to define the problem.  The 

problem here is that you have a tank partially full of fuel.  

Measurement, by necessity is taken at a point source.  That is, we 

assume the amount of fuel in the tank from the level of fuel at one 

specific place in the tank.  When the plane is accelerated, the levels 

at various points in the tank move, and the assumption is no longer valid.



You could, at the risk of complexity, compensate for this movement by 

placing several gauges at several points in the tank and integrating 

them..  The hard part is where to place the sensors, and how much 

importance to place on each.



Another option is to note that the splashing is periodic, let the gauge 

reflect that, and use the skills learned in high school chemistry class 

to interpret the results.



I think the second option is more robust.



-- 

Ernest Christley, President

Ernest(at)TechnicalTakedown.com



TechnicalTakedown, LLC

www.TechnicalTakedown.com

101 Steep Bank Dr.

Cary, NC  27518

(919) 741-9397

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