REFLECTOR: Fuel sight guages..why?

[Alex Balic]

Hi Brooke-

I for one have only the sight gauges and the fuel flow computer- IMHO the in
tank fuel gauges are a waste of panel space- or  just a waste of electricity
if you have them connected to a MFD.  The fuel flow computer can be pretty
accurate for burn rate, but not always, especially on mine, which has a
return line, so there are 2 transducers and the computer needs to do the
math to figure out how much is being burned- so less accuracy- also any
cavitation in the return line will make them even  less accurate- so I won't
really rely on them, just like I would not rely on just an airspeed
indicator and a timer to determine how far I have flown.  I have never ever
seen a truly accurate fuel quantity gauge- they are getting pretty good, but
I would never rely on one to give me accurate information other than, I have
about a half a tank, or now I have about a quarter tank- the only accurate
way to see how much fuel you have left is to do just that- SEE it- either
with a calibrated stick which is only good for when you are on the ground,
or with a calibrated sight gauge, which will tell you how much you have all
of the time-  no moving parts to break, no electricity required, and
perfectly accurate- I will use my flow meter to give general information,
and look over my shoulder to see how much gas I have- line leaks, fitting
leaks, cap leaks, compression loss on a cylinder,  electrical malfunctions,
does not matter- as long as there is gravity, and you can see, you will know
how much fuel you have.  If you read the NTSB reporter, you will know how
many pilots think that they have the fuel capacity/burn rate thing all
figured out- the lucky ones just end up in a field with a good hanger
story...

 

Alex

  _____  

From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Brooke Wolf
Sent: Thursday, February 14, 2008 9:45 AM
To: Velocity Aircraft Owners and Builders list
Subject: REFLECTOR: Fuel sight guages..why?

 

Ok Guys, I have been pondering this question for some time.  Why do we have
fuel sight gauges in our Velocities?  The rationale for my doubt is as
follows:

 

1.	Before we fly, we visually observe and measure the fuel quantities
in each tank.  We know our fuel burn.  We know flying time.  Therefore we
always know our fuel state.  Nothing else required.  Unless...
2.	We had fuel going somewhere other than into our cylinders.  IE we
have a leak!  Ok, we add fuel gauges.  My understanding is that fuel gauges
and associated sensing equipment is much more reliable than it was in my
1977 C172.
3.	Most installations have some sort of a fuel flow (fuel used)
computer to be used as a third source of fuel status.  Mine will.

 

There we have it.  Three layers of redundancy.  We could lose any two and
still be aware of our fuel state.  Why add more complexity to our machines
by bringing fuel inside the cabin?

 

Since so many people have the sight gauges, I fear I am missing something.
Your considered opinions and thoughts please........at some point I am going
to be building the strakes!  Let me know what you think.

 

Thanks...Brooke

XLRG-5

 

 

 

 

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