Fuel senders..Capacitance, floats or both?
 

I've searched the forums, and it seems that a few years ago, capacitance senders were the hot thing. Then float types were popular again. .what's the latest?
Building a RV8, thinking no flop tubes, planning to stick with 100LL (until forced to go with whatever replacement fuel they come up with. .)thoughts on having both capacitance and floats in the tanks? Seems like a lot of the bad experience with capacitance was corrosion or resistance in wire terminals. .I see now there are aftermarket capacitance probes from LMS, Prinston, CIES and so on. Perhaps they are better than the plate style vans used to sell?
I see float senders are an extra $ option on vans order sheet. What do the wings some with standard?

Any other considerations when ordering the (slow build) wings? Should I delete the fuel caps and order aftermarket upgraded like the Vans RV14 or Andair?

Thanks!

I have the capacitance probes that were current around 1999. They work, but they are only accurate at certain points. The float senders have the same issue. I'd just go with floats, do you best to calibrate them and then once flying, zero in on your fuel flow calibration. I'd use the fuel level sensors as advisory and a watch on whether I was leaking fuel. In my case, the fuel remaining calculation periodically gets close to what the level sensors say, and then they vary again.

In other words, don't obsess about this. Get the floats and move onto the next decision. My thoughts only

Another minor thing about the capacitance type is that they are sensitive to specific gravity. IOW, if you calibrate them to avgas, they will not be accurate with mogas, etc.
I've had excellent results with float senders and E.I. gauges being very accurate,

Standard kit is no fuel level sensor of any kind.
I have the grt efis, I assume the others are similar. It lets you set up a calibration table for the floats, so my float gauges, fuel flow measurement, and what the pump says I took, all agree to a gallon/tank (except that, due to wing dihedral, the floats can?t measure the top 5 gal (30 gal RV10 tank).
I use the standard caps, no issues to date.

I am using Van's capacitance plates tied into my AFS 5600T with the Dynon voltage converters. I calibrated them with 100LL in 5 gal increments in level and 3 point attitudes, I find them quite accurate and they have been trouble free.

Both + 1 extra plate
 

The cheap RV-8 capacitive sender (an isolated plate close to tank root rib and an isolated plate close to the outboard tank rib) should give you the option of full range readout. The float senders top out and don't show the difference between a full tank and about a 5 gallons from a full tank.

But, as mentioned earlier, you'll have to recalibrate the capacitive senders depending on type of gas used.

However, as I've written many times before, adding a third isolated plate near the inboard bottom of the tank (always covered by fuel), with its own separate output, would solve that issue. The electronics, that read the capacitance and converts it to a voltage for EFIS or other gauges, would have to be improved with a second input to be used as a reference capacitance of whatever fuel is in the tank. (any season of MoGas, AvGas or mixture thereof.)

I wish I'd done that in my RV-4 tanks.

I wonder if there is a market for such an electronic device? If so, I could make and sell them.

Finn

I bought my plane. It has 25 year old floats that I have calibrated via my GRT EIS to be most accurate at the bottom end of the scale, regardless of fuel type (tested both 100LL and 93 Octane E10 mogas). I then added a red cube that I have calibrated to be most accurate in cruise conditions. That works for me.

Our RV9A (pre-2003) has the original Van's plates and Dynon voltage converters.

We calibrated theM in the middle of summer with 100LL using the Dynon "add 5 litre" method. Had to drain the tanks a couple of times shortly afterwards so we took the opportunity to reverse verify. They were bang-on all the way down.

We're in winter now, if that matters, and in flight yesterday they were reading proud about 8-10 litres.

Just to add another data point.

Pat.

Is that also with 100LL?
Does the 100LL formulation change with seasons?

FInn

You know, I really don't know.

I'll have to ask but for all intents and purposes our temperature variations between summer and winter are fairly mild. Today was 23°c although usually mid teens for winter. Summer is usually high 30s with the occasional day over 40°c.