Hi! Guys,
I've been sort of watching your deliberations and have a small contribution
which may not be relevant but sufficiently important for me to speak up.
When you calibrate the fuel levels into any pressure sensing of the depth of
fuel being measured remember to "allow for" the fact that when the aircraft
is brim full the column of fuel above the tank top in the filler pipe
appears to nearly double the depth of fuel being measured.
I used to have one of Tony K's systems and so had great difficulty with
fixing the "Full" reading to actually represent the tank top volume which
greatly reduced the accuracy of the full range of readings. This is in no
way intended a criticism of his transducer system, but more an illustration
of my computer illiteracy !
For interest G-PTAG has no external tank vents but they actually pass into a
collection bottle in the cabin top( with a drain back to tank pipe) and
continue inside over the roof and down to exit near the port side flap
hinge bracket. I have never had any issues with venting or loss of fuel on
refuelling in any weather conditions or temperatures for my main Europa Tank
or my long range aluminium tank.
Regards
Bob Harrison G-PTAG Rotax 914.
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of GRAHAM
SINGLETON
Sent: 29 November 2013 09:53
Subject: Re: Europa-List: sight gauge alternative
Wonder what the difference between cabin pressure and fuel vent pressure is?
Graham
_____
From: Jan de Jong <jan_de_jong@casema.nl>
Sent: Thursday, 28 November 2013, 20:20
Subject: Re: Europa-List: sight gauge alternative
What you hope to measure is the difference in hydrostatic pressure caused by
the "column" of fluid in the tank and the same "column" of air outside the
tank.
Almost any connection from sensor to the top of the tank with not-moving air
in it will do, just like with pitot, static and stall warner lines.
Non-moving means no friction pressure drop.
Jan
On 11/28/2013 8:25 PM, GRAHAM SINGLETON wrote:
I don't believe the shape and size of the vent has any influence - the air
in the vent line(s) hardly moves.
Regards,
Jan de Jong
But it does have a pressure. That's what we are measuring
Graham
_____
From: Jan de Jong <mailto:jan_de_jong@casema.nl> <jan_de_jong@casema.nl>
Sent: Thursday, 28 November 2013, 18:57
Subject: Re: Europa-List: sight gauge alternative
I don't know whether it was mentioned but the aircraft attitude will always
have an influence on the fuel level reading.
The less one succeeds in mounting the sensor right below the center of the
tank the larger the influence.
One could measure pitch and do calibrations at several values and
interpolate.
I think that goes too far.
I don't believe the shape and size of the vent has any influence - the air
in the vent line(s) hardly moves.
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