Using engine mapping is an obvious solution especially for those computer
controlled fuel injected engines that have all the information for engine
management. However for 912 users I think the old system of sender plus
computer for about 200 remains the easiest and most cost effective for 912
and 912S owners. The elba as sold by us in the UK does have optional
threaded connection and I have put mine on the cockpit side onto aluminium
fuel lines reducing problems of fire protection.
Jerry
lts@avnet.co.uk
http://www.avnet.co.uk/touchdown
----- Original Message -----
From: Kesterton, Donald <KestertonD@logica.com>
Subject: RE: Fuel Flow guage
> Jerry et al.,
>
> Assuming it was possible to find a fuel flow system with a flow transducer
> which was accurate at the flow rates you find with a 912, would it be OK
> (i.e. work accurately) to locate the transducer in the fuel supply line to
> the carburetors, after the fuel return bleed back to the fuel tank, the
> objective being that the fuel flow transducer measures the flow to the
> carburetors only, and not the return flow. This would remove the need
(and
> expense) of a differential flow system. What do you think?
>
> Donald Kesterton
> #216
> G-PATS
>
> ----------
> From: Jerry Davis [SMTP:lts@avnet.co.uk]
> Subject: Re: Fuel Flow guage
>
> I spoke to one of the fuel computer manufacturers about this
> problem. They are looking at a solution but nothing is coming yet. The
real
> problem is the fuel return flow. I think all of the less expensive flow
> meters use impeller or vane type senders which generate frequency/flow
> signals. The problem is these devices only operate over reletivley small
> ranges. I have several senders here which work well on Rotax engines.
> Typically they measure a 10 l/hr or 25 l/hr with very acceptable errors.
The
> trouble is to have a sensor which measures a high volume you must have a
> large jet over the vane or impeller. The same sensor will not generate
> enough fluid velocity when the flow rates are low to spin the impeller.
>
> For eample a normal 912 impeller works well above 6 litres per hour
> but it may stall at a little less than this flow rate say 4 l/hr. maximum
> flow is 23 l/hr giving a range of less than 6:1.
>
> For the flow return flow rates can be higher than 20 l/hr down to
> nothing.
>
> Volumetric or displacment meters may be the only solution but they
> are expensive and I have no experiance with these devices.
>
> Jerry
>
> lts@avnet.co.uk
> http://www.avnet.co.uk/touchdown
>
> ----- Original Message -----
> From: Michael Dawson
> Subject: Fuel Flow guage
>
> Could anyone out there advise me of a reasonably priced fuel
> flow guage ? the cheaper one sold by RD has a 1/8th Inch orifice in the
> transducer which I understand gives flow problem from time to time - their
> expensive one is very expensive as with a 914 you need and extra
transducer
> and the lot comes to well over 1000.
>
>
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