Fuel Flow Meter - RC Groups
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Oct 29, 2011, 04:24 PM
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Discussion

Fuel Flow Meter


I am doing a research project that includes the use of a Zenoah G260RC gas engine and a large aircraft. I need to measure the fuel flow into the Zenoah. A search of the internet has found no fuel flow sensor of this size.

Does anyone know of such a sensor?

Much thanks!

Brian
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Oct 29, 2011, 08:13 PM
Registered User
Nope...fuel flow is kinda useless info...it will warn you of a problem in full scale such as a fuel line has ruptured or your engine as crapped out the fuel control or carb...but in RC it would be info after the fact.....
But what you can do is simple math....run the engine for a set time at a set throttle position measure the fuel used divided by the time ran....problem with that is cooling air if you run the engine on the ground for an extended period...
Oct 30, 2011, 12:57 PM
Registered User
The project entails a hybrid power system on a UAV, real time fuel flow is required.
Oct 31, 2011, 10:51 PM
Gas Only
Fokker DII's Avatar
After the fact fuel flow is more of a wish list item than an item of importance? Your research team needs to research how to get it.
Nov 03, 2011, 05:10 PM
Stuck on Cyanoacrylate!
What are you guys smoking???

Fuel flow is INCREDIBLY important information to have for a long endurance UAV.

Sorry though, I don't know where you would find the sensor though. But, I'm sure there is a company somewhere that makes them, or can make them. All it takes is $$$.
Nov 03, 2011, 11:39 PM
Dieselized User
gkamysz's Avatar
Fuel flow is not so important you need real time data unless you are using it to adjust the mixture for the engine. Automobiles don't use a flow meter. The fuel injectors have known flow characteristics and with the duty cycle you can determine fuel flow rate, but mixture is determined by closed loop feedback from the O2 sensor.

What are you going to do with real time data?

Greg
Nov 04, 2011, 06:52 AM
Registered User
First off he never said what the data was for
second so you have fuel flow info...now it pegs high what do you do? shut down the motor?
Nov 04, 2011, 09:17 AM
Registered User
Toysrme's Avatar
FPV camera pointed at fuel tank
or
why dont you simply do some timed flights at X throttle & see how much fuel you burn...
Nov 04, 2011, 09:34 AM
Stuck on Cyanoacrylate!
I think you guys are keeping this too simple. Think about the mission of a UAV, the length of time it is going to remain airborne, and what kind of requirements you have for mission success. I don't think this is just a fancy RC airplane that is going to stay in visual contact with the pilot. Going beyond visual range, and putting it down somewhere (not recovering the vehicle) because of something stupid like fuel exhaustion/fuel starvation is just as unacceptable as it is for a manned aircraft.

If FF goes off-scale high, then you keep a close watch on fuel quantity for a period of time. If the level decreases close to the known rate, then you can have a high degree of confidence that you don't have a fuel leak and only a failed telemetry channel.

If this UAV goes up to high altitude (over 3000' AGL), you have to lean the fuel mixture as you go higher. To do this, likely EGT will be the primary indicator for mixture, with fuel flow as a supporting parameter. Fuel level vs. time will also be a secondary check on fuel burn rate/mixture and the accuracy of your fuel flow transducers.
Nov 04, 2011, 11:23 AM
Dieselized User
gkamysz's Avatar
Engine management will be independent of any safety device you need to make sure you have fuel on board. It appears you already have a system to determine how much fuel you're carrying. The the flow meter is to determine if fuel is leaking? Do man carrying aircraft have systems like this? What is the probability of a fuel leak upstream of the flow meter?

If you're limiting your internet searches to "fuel flow meter" that's your problem. You want a liquid flow meter compatible with the type of fuel you're burning, plenty of stuff out there.

Greg
Nov 04, 2011, 12:03 PM
Registered User
Yes full scale aircraft use fuel flow...I use it during starts as a good indication of a pending hot start.....
Like you said if fuel flow goes high then you watch fuel quanity.....fuel quanity is a better indicator of a leak because it's at the tank...and covers the complete fuel system...
where as fuel flow only tells you what happens past the transmitter....
Nov 04, 2011, 01:23 PM
Dieselized User
gkamysz's Avatar
Is there a fuel flow meter in the system or is it calculated from pump characteristics? Piston aircraft too? Mostly my curiosity talking here.

Greg
Nov 04, 2011, 02:44 PM
Registered User
earlwb's Avatar
Most low volume flow meters tend to be a tube with a scale on it, not exactly something you can hook up to a computer to store data with.
But maybe if the flow resistance of a compact magnetic flow sensor is low enough, then one of these might work.
http://www.flow-network.com/magneto_...meter_mik.html
the ultrasonic one might work even better too
http://www.flow-network.com/compact_...meter_duk.html

You will need to make a adapter for the fuel line to feed into and out of the flow sensor.
Nov 04, 2011, 09:07 PM
Gas Only
Fokker DII's Avatar
Realtime fuel flow will not tell you anything about remaining fuel. It will tell you what you are using in this moment but will not tell you what you used a few minutes or even seconds ago. Full size aircraft have a fuel gage and piston engines are leaned out at altitude with an EGT there is no real time fuelflow meter in my Comanche.
The researtch project is not explained so me thinks it is an excercise in questions reather than any research.
Nov 04, 2011, 09:45 PM
Registered User
I can think of two ways to do it. First is with a liquid flow sensor made by Honeywell. They should have a flow sensor in the range you want. This sensor works like an anemometer but at the micro chip level. The second way is with two pressure sensors and a restriction in the flow line. You need to measure the pressure drop across the restriction in the flow line. You will need to create an algorithm that gives you flow VS pressure drop. It should be proportional. You can also get the pressure sensors from Honeywell. I know they make them down to 4 inches of H2O.
Look into Honeywell Sensing and Control division in Freeport Illinois.

It has been a long time since I have worked with these types of sensors but I have seen flow measured using both of these methods.

Pete


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