Belite Fuel Level System

[skippydiesel]

16 hours ago, Thruster88 said:

The belite system using pressure is to me an example of shit engineering in the modern world. Low on fuel? Just pull 2 g's and you will have twice as much.

Your point being???

 

As a pilot I would expect you to understand the limits of your aircraft systems - short duration false readings/spikes are accommodated by the systems buffering/smoothing of the read out.

 

Longer term erroneous readings, in this case  when sustained above ambient  pressure  is crated within the tank, from the breather will give a false reading.

 

The majority of sensors register pressure of liquid at one end and atmospheric at the other. To be effective, an aircraft fuel sensor must register liquid at one  end and tank internal pressure at the other.

 

I have found one pressure sensor that has its own atmosphere breather tube (rather than a small hole in the "back" of the sensor )https://www.safiery.com/IP67-tank-level-sensor-external-pressure.

 

The Sefiery product looks to have the correct configuration, to sense liquid above and pressure acting on the same liquid. UNFORTUNATLY the breather tube (designed to sense atmospheric pressure) when connected to the tank breather has the potential to deliver an air fuel mixture to  the internal electrics of the sensor - this presents to me, as a potential for ignition.

 

 

[skippydiesel]

16 hours ago, Blueadventures said:

its all about in tank pressure  -  this is the issue you will not solve.

Wow! do you always give up so easily?

[Blueadventures]

1 hour ago, skippydiesel said:

Wow! do you always give up so easily?

I'll allow you to decide that.   I was just trying to assist you with your fuel contents measuring.

 

I'll stand by my earlier comment; and after viewing the belite demo it reinforces my refusal to ever use their system in an aircraft wing tank (could work ok in a tall narrow collector / surge tank).

 

I'll bet they never show a demo of the sensor performance fitted to the side of a typical aircraft wing tank and then simulate pitching and rolling movement; will not be a good demo regarding accurate quantity readings.

 

I find UMA good instruments; perhaps retro fit their sensor setup.   If your tank is well baffled it will see better more accurate readings.

 

Hope this assists you somewhat.

[skippydiesel]

Blue - no offence mate but you seem to be fixated on fuel slop/agitation as somehow being the problem - its not!

 

The problem is the fuel sensor (simply a sensitive pressure sensor very similar to oil/fuel pressure sensor) is being confused by  the fuel tanks internal pressure,  when the internal pressure differs from ambient (in fuselage in my application). Higher + pressure  will read as more fuel Low - pressure will read as less fuel (in fuse pressures may also impact on readings) 

 

There are only three potential fixes (aside from capitulation):

• A second sensor that registers in tank pressure  - Possible but very expensive.
• A single sensor that is connected to in tank pressure - This is the Safiery model. As stated it seem that it may present as an ignition risk.
• Having in tank pressure the same as ambient (STATIC) -  The practicality of this seems unlikely, as routing the tank breather to always/mostly deliver static pressure seems to elude me.

 

The solution's are  obvious,  finding the parts/components to achieve the fix, less so - hence my questions.

[Thruster88]

Your solution could be like the the little old lady that swallowed the fly.... or change to a sensor that is not dependent on pressure.  

[facthunter]

There are few fuel indicators that can be relied upon especially in U/L's. With long thin wings especially. Legally you can't rely  on any of them alone for determining fuel contents. With a direct sight tube or a connected float you can rock the wings and get a slightly more  assured reading  when you are sighting actual fuel. as far as I'm concerned. It doesn't require electrical power either. Nev

[Kyle Communications]

How can your internal fuel tank not be at the ambient pressure...It does have a breather..that keeps the tank at the ambient pressure

 

[skippydiesel]

Just now, Kyle Communications said:

How can your internal fuel tank not be at the ambient pressure...It does have a breather..that keeps the tank at the ambient pressure

 

 Many/most(?) small aircraft fuel tank breathers are configured to deliver positive pressure to the fuel tank(s) Problem 1

 

Problem 2.The fuel tank is question, is in the fuselage that is subject to pressure changes as a a result of the crew opening/closing fresh air vents &  Bernoulli effect.

 

The sensor is responding to the weight of fuel above it RELATIVE to the pressure outside the tank, when it should be RELATING to the pressure inside the tank.

 

So the impact of 1 and/or 2 on the fuel tank level sensor is, either high/low false reading dependent on the relative in tank/ to outside tank pressure.

[Kyle Communications]

I dont know about your assumption of number 1...I know plenty that dont have positive pressure into the fuel tank.

I actually made my own pressure sender and trialed it on a tank similar to the belite system about 2 years ago. It used the weight of the fuel as the pressure value....in all the testing I did on it I deemed it a failure. G forces on the fuel threw it all totally out. I used a high end 4-20ma pressure sensor and placed it in the bottom of a 10 litre tank and a 20 litre tank..did some real world testing on it using code I wrote just to monitor the values of the sensor...it was not stable enough for my liking. I looked for some pics I took but cant find them...I may have them on my work computer and I will have a look tomorrow. I say you cant beat sight gauges though.

 

[skippydiesel]

11 hours ago, Kyle Communications said:

I dont know about your assumption of number 1...I know plenty that dont have positive pressure into the fuel tank.

I actually made my own pressure sender and trialed it on a tank similar to the belite system about 2 years ago. It used the weight of the fuel as the pressure value....in all the testing I did on it I deemed it a failure. G forces on the fuel threw it all totally out. I used a high end 4-20ma pressure sensor and placed it in the bottom of a 10 litre tank and a 20 litre tank..did some real world testing on it using code I wrote just to monitor the values of the sensor...it was not stable enough for my liking. I looked for some pics I took but cant find them...I may have them on my work computer and I will have a look tomorrow. I say you cant beat sight gauges though.

 

Very interesting Kyle.

 

Personally I would not have gone down this path but the aircraft ( a near completion home built) came with the (expensive) Belite system so giving it a fair go.

As for G loading - not really a problem if the pilot is aware that the system needs  to "settle" for an accurate read out - who reads their tank level in a +/- G manoeuvre anyhow?

Sight gauge/ tube - agree 100% however the aircraft tank system must be such that this can be  installed & seen - I already have some ideas about installing one (using a reversing camera and 100mm screen) - biggest problem will be obtaining the right tubing, so that the fuel level can be readily seen 

[Kyle Communications]

What about on those days like like riding a rollercoaster or just outright bumpy all the time..then its almost useless...cant beat sight gauges...but a low wing is a issue...capacitive type would be a better solution I think

 

[skippydiesel]

57 minutes ago, Kyle Communications said:

What about on those days like like riding a rollercoaster or just outright bumpy all the time..then its almost useless...cant beat sight gauges...but a low wing is a issue...capacitive type would be a better solution I think

 

Thanks for that Kyle.

 

As you may have noted, from earlier posts, my Son has been the brains behind trying to make the Belite system work (against all the evidence that we found On Line). 

 

My Sonex is in "the shop" for a range of modifications/tweaks - while  in this striped down condition, is the time to make whatever changes might deliver  better outcomes -

 

Son advised , about an hour ago, that he doesn't like the odds of the Belite ever being a reliable fuel level reporting system. In the light of this - I  have pulled the plug on the system. It will be removed and conventional level sensor/sender installed (suggestions & advice welcome)

 

My thanks to all those who tried to assist in the face of my dogged persistence

[facthunter]

The DHC-1 Chipmunk has fuel indicators on the top of each wing with two scales  One for level and the other when tail is on the ground that can be seen from the cockpit. Nev