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Steve,
I used the Texas Instruments Launchpad development kit for the fuel flow device. The programming board and two imbedded microprocessors cost $5.00 at the time. The software was downloaded at no cost. Additional hardware was needed but the cost was minimal.
The flow vs. time characteristic for the fuel injectors is linear with a non-zero intercept. This can be used in the microprocessor calculation. Different sized primary and secondary injectors can be accommodated by using the corresponding characteristics. The fuel flow indicated by a simple conversion of pulse width to voltage will be most accurate only at the condition under which the calibration was developed although the result may very well serve your purpose.
I scaled the variables so as to use integer arithmetic with the MSP430G2211 and MSP430G2231 chips that came with the Launchpad kit. The device I built indicates RPM, staging condition, fuel flow rate, and fuel remaining in each of my two wing tanks.
The requirements for building an accurate and dependable instrument can be avoided by installing the single flow sensor connected to your Dynon. It just depends on what you want to spend your time and effort on.
Steve Boese
> On Jul 26, 2017, at 10:43 PM, Stephen Izett <flyrotary@lancaironline.net> wrote:
>
> Thanks Steve
> Rather than reroute the fuel lines I think I’ll build a little processor and measure pulse widths and rpm and create a pulse stream fr the dynon to read.
> Any hints on anything to watch out for in coding?
> Cheers
>
> Steve
>
>> On 27 Jul 2017, at 12:39 pm, Steven W. Boese <flyrotary@lancaironline.net> wrote:
>>
>> Steve,
>>
>> I have a single flow sensor installed in a dead headed configuration as Charlie described as well as a flow indicator/accumulator of my own design based on the primary and secondary injector signals. They are both consistent and accurate.
>>
>> Steve Boese
>>
>>> On Jul 26, 2017, at 8:26 PM, steve Izett <flyrotary@lancaironline.net> wrote:
>>>
>>> Thanks Charlie
>>> Appreciate the info re position of regulator.
>>> Steve Izett
>>>> On 27 Jul 2017, at 10:08 am, Charlie England <flyrotary@lancaironline.net> wrote:
>>>>
>>>> On 7/26/2017 4:58 PM, Neil Unger wrote:
>>>>> Gents, Is anyone aware of a fuel consumption gauge that will give fuel consumption in real time? I can get one that has two flow meters but that makes installation complicated and not really cost effective. I am looking for something that works off the injectors. As usual it has to be "tweaked" with actual fuel usage. Did not Tracy have such a system? Neil.
>>>>>
>>>>>
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>>>> Just about any fuel flow instrument will work, if you design the fuel architecture to allow it. If you place the regulator & its bypass prior to the flow sensor & injectors, you only need one sensor. The fuel 'dead heads' at the injectors, so it's always at full system pressure, and in the unlikely event that there is vapor in the lines, it's immediately blown through the injectors. It's how virtually every car is set up these days. It's being done in a/c, too. I'm pretty sure that Tracy has this fuel delivery architecture in the RV-8 3-rotor.
>>>>
>>>> If you're patient, you can find Flowscan sensors & various brands of totalizers on Ebay for very good prices.
>>>>
>>>> Charlie
>>>>
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