Thanks for your reply Carl.
I am using the BMW R11100 which has Motronic fuel injection. This is regulated
at a constant 3 bar pressure. When the electronic injector is open, then fuel is
squirted in at a constant and known (or at least measureable )rate. The
injectors are operated by ground-side switching from the ECU. So all I need to
do is integrate the "on" pulses from the ECU; an analogue voltmeter connected to
the "switch" in the ECU and with appropriate shunting (and flyback isolation) to
give FSD when constantly on should get me into the right ball park. Obviously
there is a lag in fuel delivery when the injector first opens so that less fuel
will flow when high frequency, short duration pulses are signalled as opposed to
low frequency long duration pulses. The dedicated advocate could probably tune
the circuit to cope with this, but it may all work well enough without.
Re. a nice display for a system with a flow sensor:
The cheapest way is to use a digital bicycle mileometer to receive pulses from
a flow sensor ( which may need to be conditioned and/or prescaled prior to
interfacing with the mileometer). The mileometer (which sell for about L20) will
readout gph (instead of mph), gallons consumed on current flight since last
reset (instead of miles), total gallons (miles) consumed and will enable you to
set an alarm to go off when ` x` gallons have gone (ie when you are down to your
last gallon!). The facility on the mileometer for calibrating it to different
bicycle wheel sizes can be used for calibrating to different flow sensor outputs
(within limits). It also has a clock, alarm and stop-watch function. Not bad for
the price!
Rgds. Duncan McFadyean.
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