Hello,
D-EUPA has the same trouble as you all have indicated here. To correct the
missreading when filling up wit Avgas or Mogas, I came to the same conclusion
then Ferg did: the capacitance gauge wants to know what it's looking at.
However, my solution was a bit different.
A second, shorter (about 10 cm) capacitance probe is being buried horizontally
down into the lowest position of the tank. I already have a micro controller
on board to convert the fuel level to volume, so I could feed the reading of
the short probe to the micro controller. The short probe would be giving a
capacitance reading the correlates to the -defined- length of it. That value
would than be used to calibrate the real fuel probe - just a bit of
arithmetic is needed. The obvious advantage: even a mixture of Avgas and
Mogas would result in a correct reading.
Will I change my setup to the above? Probably not. I consider one more
alternative, namely going to the factory mod 60 schema. Much simpler, and
probably more reliable.
Norbert, D-EUPA
Am Mittwoch, 25. Mai 2005 03:03 schrieb Fergus Kyle:
>
> hey!
> That's the trouble with capacitance - it wants to know what
> it's looking at.......
> However, it IS capacitance. Therefore one could 'fudge' the reading by
> adding or applying a subsidiary capacitance (or if it's calculated to
> resistance at the gauge) to fool it. That would mean working out a circuit
> to insert for whichever parameter one wants - say, 100LL or Mogas. I'm not
> there yet, but will have to do something like that if I want accuracy.
> Failing that, one could apply a secondary scale to the gauge to
> read the secondary fuel type quantity. Whichever method means measuring,
> measuring and plotting.
> Good luck, I think,
> Ferg
> A064
> Oh, oh. I think PFA may want a word over there...................
>
> ----- Original Message -----
> From: "Rmi Guerner" <air.guerner@wanadoo.fr>
> To: <europa-list@matronics.com>
> Subject: Europa-List: funny fuel gauge
>
> |
> |
> | Hi all,
> | Surprisingly I get just the opposite with the Avelec capacitance fuel
>
> gauge: when full with mogas I consistently read 60 liters, and with Avgas
> 100LL I read 50 liters.
>
> | I also have another problem with this fuel gauging system: from time to
>
> time I have an "fuel tank fault" indication, or zero indication while the
> tank is full. Very difficult to troubleshoot as the problem is
> intermittent. Yesterday it happened only during a few minutes in the middle
> of a 3 hours flight. Any idea?
>
> | Remi Guerner
> | F-PGKL, XS 912S, s/n 395 monowheel, 320 hours
> |
> |
> | Subject: Re: Europa-List: Funny fuel gauge
> |
>
> <peter.rees05@ntlworld.com>
>
> | Thats exactly the problem we had. Problem is that the gauge was
> | calibrated for Avgas - when we changed to Mogas, the gauge said that the
> | tank was always 3/4 full.
>
|