Van's Air Force
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Capacitive Fuel Senders
- Thread starter Robert M
- Start date
Robert M said:
No moving parts and they don't wear out. They're literally just two plates of metal with wires coming off them. You could make them yourself out of a couple of pieces of scrap if you felt like it (just buy Van's...it comes with all the bushings and things).
Can they fail? Anything can fail. Most likely, it'll be your electrical connection if anything. A nice big glob of proseal over the connector will immobilize it and keep it from fatiguing, so that probably won't fail either.
re: replacement. Doing anything in a fuel tank is a pain in the butt. There'd likely never be a reason to touch them for the life of the plane.
I'm not sure they actually perform any better in practice than floats, to be honest. I've been told that they're flaky if you change fuel (i.e. 100LL and mogas, etc...). Also, I did a back of the envelope calcualtion once and it looked like if the humidity took big swings that could throw things off a little bit too...not sure how much. It seemed like it COULD, though. Someone with more experience could talk to this.
Performance aside, I'm installing them 'cause it's one less thing that can break, stick, come loose, etc...
N916K
Well Known Member
Robert M said:
1. No moving parts
2. Nothing to really wear out but some people have the B&C connectors leak. One of mine did so I packed it with fuel lube and I haven't had a drop of fuel leak sense.
3. The sending unit is just two aluminum plates bolted inside the tank with a wire connected to them. The electronics are all outside the tank.
I have the the capacitive fuel senders in my 9 and like them. I will probably be putting them in my Rocket. One thing that you may not know is that the Van's kit is just for the aluminum plates, you still have to buy the electronics that connect to the plates. They are about 100 dollars a tank. What the electronics do is read the capacitance from the plates to the tank and convert that to a voltage for the engine monitor to read. I belive some of the engine monitors are starting to included these electronics but I would quess you aren't going to get away without paying an extra 100 dollars a tank for capacitive senders.
Looks like John pressed send before I did.
One thing about how well they work. Mine is good at full and below 1/4 tank. In the middle they are off a bit. Altitude and temprature really effect them. But when they get down low it seems to work very well. I ran each tank out of gas (no, not during the same flight) and a few seconds after the capacitive gauge said 0.0 gallons my engine died.
Last edited:
I got 'dem quick, software engineer fingers
Has anyone heard anything about the sensors that GRT sells? Princeton, I think. I remember reading somwhere that they work much better then Vans. It was a while ago, before I even decided to build the -7, so I just kinda' spaced and didn't pay much attention.
Has anyone heard anything about the sensors that GRT sells? Princeton, I think. I remember reading somwhere that they work much better then Vans. It was a while ago, before I even decided to build the -7, so I just kinda' spaced and didn't pay much attention.
N916K
Well Known Member
jcoloccia said:I got 'dem quick, software engineer fingers
Has anyone heard anything about the sensors that GRT sells? Princeton, I think. I remember reading somwhere that they work much better then Vans. It was a while ago, before I even decided to build the -7, so I just kinda' spaced and didn't pay much attention.
They aren't really sensors. It's more of a probe and a converter. You get the probe (two aluminum plates and a wire) from Van's and the coverter from a different supplier. I believe Van's sells the EI and ACS converters. I think the EI works only with the EI gauge, not sure about the ACS conveter. The Princeton (basicly that's just someone at GRT) works with a few different engine monitors. I you need to check with the engine monitor company before purchasing a converter though.
I have the Princeton converter and it was easy to setup and I haven't had to touch it sense.
AntiGravity
Well Known Member
Capacitive senders, princeton converters
I've contacted both Dynon (EMS-D10) and Advanced Flight Systems (AF-2500) about their systems and both have advised either float or capacitive. Dynon specifically mentioned the Princeton capacitive units as sold by Aircraft Spruce (see http://www.aircraftspruce.com/catalog/inpages/princefuelprobes.php). Ken at AFS also said I can buy the adapters for the capacitive senders from Vans, though he didn't specify exactly which. I had my tanks made for me by Evans Aviation and had Evan install the capacitive senders; his advice was basically less to break and less chance of leakage. I just like the idea...
Cheers,
I've contacted both Dynon (EMS-D10) and Advanced Flight Systems (AF-2500) about their systems and both have advised either float or capacitive. Dynon specifically mentioned the Princeton capacitive units as sold by Aircraft Spruce (see http://www.aircraftspruce.com/catalog/inpages/princefuelprobes.php). Ken at AFS also said I can buy the adapters for the capacitive senders from Vans, though he didn't specify exactly which. I had my tanks made for me by Evans Aviation and had Evan install the capacitive senders; his advice was basically less to break and less chance of leakage. I just like the idea...
Cheers,
Robert M
Well Known Member
Capacitive Fuel senders
Thanks guys!
In the begining I planned to use the tried and true float type fuel system. However, the FlightDEK 180 just blows my kilt up and, if I'm not mistaken, that would require capacitive sensors. Here's the dilema, I'm about 3 to 4 years from panel construction so my choice of panel instrumentation may change. The type of fuel sending units have to be chosen when the wing is built. I firmly believe that technology is on my side in this area and most manufacturers will utilize capacitive. I guess I just need to talk to Dynon and be sure I get compatible equipment.
If I was reading the information at the vans web site correctly, I believe they offer the converters for both types of gauges.
Thanks again,
Robert
Thanks guys!
In the begining I planned to use the tried and true float type fuel system. However, the FlightDEK 180 just blows my kilt up and, if I'm not mistaken, that would require capacitive sensors. Here's the dilema, I'm about 3 to 4 years from panel construction so my choice of panel instrumentation may change. The type of fuel sending units have to be chosen when the wing is built. I firmly believe that technology is on my side in this area and most manufacturers will utilize capacitive. I guess I just need to talk to Dynon and be sure I get compatible equipment.
If I was reading the information at the vans web site correctly, I believe they offer the converters for both types of gauges.
Thanks again,
Robert
John C
Well Known Member
GRT/Princton
Mine work great. There was a calibration problem for the -9 (different plates than the 7) but GRT fixed it right away. There are 5 set points so the accuracy is good at each quarter tank. I made a calibrated dip stick as I filled the tanks to calibrate the units. There seems to be no change after 7 months and 70 hours.
Mine work great. There was a calibration problem for the -9 (different plates than the 7) but GRT fixed it right away. There are 5 set points so the accuracy is good at each quarter tank. I made a calibrated dip stick as I filled the tanks to calibrate the units. There seems to be no change after 7 months and 70 hours.
Yeah, but not yet. He was talking about either the electronics in the panel -or- a doohickey to interpret the capacitance and convert it to a resistance for use by a standard fuel gauge. Whether you need the doohickey depends on what type of fuel gauge you end up buying.
...so for now all you need are the sensors.
Davepar
Well Known Member
I'll make the dissenting post on the cap senders. Next time, I would just use the floats. I'm a high-tech guy, but the capacitive probes aren't worth the hassle. The floats are easier to install and don't require $200 for the converters. If you're going to use a fancy engine management system like the AF-2500 or GRT or Dynon units, you'll probably have a fuel flow sensor. You hit a button on the EMS when you fill up and that sensor gives you an accurate reading of fuel remaining down to the 0.1 gallon. The fuel senders (cap or float) are just a back-up. If you develop a leak in one tank, the sender will tell you something's wrong. Thus it's not worth going super fancy on the senders.
The only downside with the floats is that they have to be replaced eventually (5, 10 years? something like that). Fortunately that's easy to do since they're screwed in right at the wing root. If you develop a problem with the cap senders... well you'll probably just fall back to using floats.
It looks like the Spruce link above is for a converter plus probe. You just need the converter. I ordered directly from Todd at Princeton, although it looks like I paid the same as the Spruce price.
Dave
The only downside with the floats is that they have to be replaced eventually (5, 10 years? something like that). Fortunately that's easy to do since they're screwed in right at the wing root. If you develop a problem with the cap senders... well you'll probably just fall back to using floats.
It looks like the Spruce link above is for a converter plus probe. You just need the converter. I ordered directly from Todd at Princeton, although it looks like I paid the same as the Spruce price.
Dave
Robert M
Well Known Member
Davepar said:
I guess I should read more about the function of the Dynon FlightDEK 180 so I would have a better understanding of what I plan to buy.
So, Dave, if I understand you correctly, the fuel flow tells the Unit (say - the Dynon) that my fuel flow is X number of gallons per minute/hour? Then it calculates how much fuel is left in the tank based on the "full tank" amount I programmed during instalation minus the amount of fuel that has passed the fuel flow sensor? 
rzbill
Well Known Member
If gage "convertor" costs are an issue and one is electronically savy, the plans to build them are available at:
Jim Weirs Articles
The BMA units do it a little differently since they purchase a packaged Frequency to Voltage convertor chip and are constrained a little by the chip functionality. Not necesarily better or worse, just different than the discrete component schematic show by Weir.
I am coin tossing between these options right now.
Jim Weirs Articles
The BMA units do it a little differently since they purchase a packaged Frequency to Voltage convertor chip and are constrained a little by the chip functionality. Not necesarily better or worse, just different than the discrete component schematic show by Weir.
I am coin tossing between these options right now.
Davepar
Well Known Member
Robert M said:
Correct. Mostly. I'm not flying yet, so this is all based on info that I've read. The fuel flow sensor sends a signal to the engine management system (EMS) every time a certain very small quantity of fuel goes by. The EMS then converts this into gallons/hour and total fuel used. As part of the installation process, you can tweak the "K factor" for the sensor so that it's very accurate, assuming you've installed the sensor in an optimum spot. I've read some people having some slightly false readings when they have the electric boost pump on, but that shouldn't affect the reading too much since the boost pump is only turned on periodically.
Depending on the EMS, the quantity remaining display is usually based on the fuel flow sensor. The EMS usually also displays the quantity of fuel from the float or cap sender. A smart EMS (don't know which ones do this) will notice a big discrepancy between the two and alert you to a possible fuel leakage. Or inform you when you've neglected to tell the EMS that you've added fuel. When you fill up you tell the EMS that the tanks are full (to the pre-programmed level) or you added X gallons of fuel that read off the pump.
Thus the float or cap sender performs sort of a back-up function when you use a fuel flow sensor and an EMS.
Dave
Robert M
Well Known Member
To capacitate or not
Thanks again Dave. As my signature cluster says, I haven't even started contruction of the tail. I have a long way yet before the wing tanks will be built. I'm still leaning towards the capacitive - but like you said - the converters are expensive and the floats are easier to install. I wish somebody would make up my mind, where is my wife?
Thanks again Dave. As my signature cluster says, I haven't even started contruction of the tail. I have a long way yet before the wing tanks will be built. I'm still leaning towards the capacitive - but like you said - the converters are expensive and the floats are easier to install. I wish somebody would make up my mind, where is my wife?
I can't think of a simpler system than to go with the capacitance senders as sold by Van's.
What can go wrong with two aluminum plates, isolated from the tank electronically speaking, with one wire running from one to the other and then out the root end of the tank? The only point of failure is in your wiring and that is very easy to reduce down to a probability of next to nothing.
I have the cap senders with an EI fuel gauge (FL-2C). Since my 6A has just gotten airbourne lately, I have limited experience with the setup, but I will relate what I have found. I needed to fill my tanks, and had determined, by the total amount shown on the EI guage, that I needed 18 gallons total. Filled up and I was off my .4 gallons.
As was said before, put the capacitance plates in your tanks. If you use them...great. If not, you can always go to floats. One word of caution. If you set up your guage for 100LL and then switch to auto fuel, you will get errors in quantity of fuel on board. You will need to recalibrate your guage if you decide to stay with a different grade of fuel after initially setting things up.
Regards,
What can go wrong with two aluminum plates, isolated from the tank electronically speaking, with one wire running from one to the other and then out the root end of the tank? The only point of failure is in your wiring and that is very easy to reduce down to a probability of next to nothing.
I have the cap senders with an EI fuel gauge (FL-2C). Since my 6A has just gotten airbourne lately, I have limited experience with the setup, but I will relate what I have found. I needed to fill my tanks, and had determined, by the total amount shown on the EI guage, that I needed 18 gallons total. Filled up and I was off my .4 gallons.
As was said before, put the capacitance plates in your tanks. If you use them...great. If not, you can always go to floats. One word of caution. If you set up your guage for 100LL and then switch to auto fuel, you will get errors in quantity of fuel on board. You will need to recalibrate your guage if you decide to stay with a different grade of fuel after initially setting things up.
Regards,
Davepar
Well Known Member
You answered your own question:painless said:
If you mix auto and 100LL on a regular basis things will really be messed up. I'm not trying to change the world. I just want to point out the downside of the cap plates.painless said:
Mel- I have no hard facts about the floats needing replacement. I just remember somebody saying they had to replace their floats at some point and that it wasn't difficult to do. I defer to your much more vast experience.
Dave
