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Fuel level Sender

Bluelabel

Well Known Member
I know there have been threads on this, I've read them all, but I can't find any real good answers. (Btw, first time builder, so you may have to fill in some of the blanks)
About to be building the tanks, and I'm looking for the best option for the fuel level sender to go to the EFIS (prob going with AFS). When I say best, I mean accurate (as can be based on the shape we're dealing with) and reliable.
I know there are many options, but would like to hear from some people as far as what they are using, have used, and how they like them.
I've heard about the Cap plates from Vans. (Heard both good and bad things, also heard Vans themselves don't recommend), but can't find them in the catalog.
I've heard about converting the floats to cap via a Dynon adapter.
I've heard about using a system from Princeton Electronics, but not exactly sure how it physically goes into the tank and if it works as predicted.

Any input would be great, esp with pictures. Also, actual part or model numbers where applicable if you have them.
Thanks in advance....
 
John,

I understand your position, as I was in it too not so long ago. I am not flying yet, so I can't say how my system performs; only what I did. I decided to install the cap plate senders but also installed the floats as well (for options). To do the cap plates, you order the kit from Vans for an RV 7,8 or 9, it doesn't matter. All you use out of the kit is the hardware and instructions (and you can return what you don't use to lower the cost). For the 10 you have to fabricate your own plates, but it's really no big deal. There are some who have even posted the dimensions of the plates online (PDF you can download). Basically, the plates must be about the size/shape of the front portion of tank rib, minus the spacing dimension from skin, rib flanges and stiffeners, which is all the same dimension (7/16" I think, but it's in the instructions). Then you install those plates according to the instructions in the kit. I've heard the cap sender setup is more accurate and less "jumpy" than the others, but I've also heard bad things too, which is why I left myself the option of the floats. Not much extra weight or complexity to do both. We'll see which one I prefer...
 
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To be honest, I think that you are over thinking all this.......

The floats aren't designed to be overly accurate. I personally think they work just fine. If you are managing fuel levels that close, then that's a topic for another conversation.

I have a variety options available to me to manage fuel levels.

1. a calibrated fuel stick, which is probably more accurate than the floats. You can make your own or buy a generic one from ACS. I calibrated mine when I calibrated the fuel guage on the EFIS. I always use this as a visual indicator of how much fuel I start out with.

2. The fuel guage on the EFIS driven by the floats. Once calibrated, it should tell you within a few gallons what's left in the tank. This will depend on what EFIS you use and how many sampling points you can take. AFS can track more than you'll need.

3. A low fuel annunciator. I installed the low fuel sensor from aircraftextras.com. Clearly not a required item, but it will let me know when I'm down to five gallons in each tank. With normal reserves and switching tanks regularly, these should never light up.

4. Fuel flow sensor. The infamous red cube does a great job at tracking how much fuel you used. Assuming that you tell the EFIS how much fuel you are starting off with, it works pretty good. I've found that is way more accurate than the floats from my use in a Cherokee. I have no reason to suspect it will be any different in the RV-10. My first flight is
imminent. I use this as my primary guage of how much fuel is left, with all the others as backup.

For me, I didn't think the cost of the capacitance sensors were worth the extra expense and effort to install. I'm sure that there are others that think otherwise.

bob
 
We use the stock floats calibrated within the Dynon Skyview and the red cube. 270 hours in and, so far, it's always only a gallon or two off. We could probably remedy that by recalculating them if we tried but we don't run the tanks that low.
 
I used the Princeton probes. Not flying yet but they came pre bent, and installed in the holes where the float senders go. So far, a lot less "tricky" to install than bending and installing the float wire and sender...
 
I used the Princeton 5 point set probes 24" long with standard hockey puck mount. Very accurate readings once the probes are calibrated.
 
Fuel Indication

John

What i did was, purchased the vans 9 kit. Made new plates to fit the main rib center part of the rib. I added a additional screw attachment. 2 in the front part of the plate and 2 in the back. So I have to order some extra plastic washers and tube from vans. They turned out great. I used the Dynon cap adapter as it will work with dynon or Garmin EFIS. I have chosen Garmin.

AFS makes there own adapter as it works on 4 volts not 5 like dynon or Garmin.

http://websites.expercraft.com/jcrv10 I have a lot pf pics on my builders log.
 
Thanks!!

Thanks guys for the info and ideas. Just what I needed. Some very detailed no and logs. It's making sense now.
And yes, I am one of those guys who over thinks things, over engineers things and want to make things bullet proof and have redundant backups. Of course, I also like the most direct path as well.
I do like the idea of putting in both floats and capacitance. I'll probably put a traditional fuel gauge somewhere kind of hidden. That way even down the road if something fails, I have options that don't involve getting into the tanks again.
 
One more for simple and cheap Vans setup.

My fuel flow totalizer is very close to what the gauges read, and I did not take any extra effort to program the EFIS.

Also another vote for a tank dip stick------make it when you do the first fill, mark it with something the fuel will not dissolve. I even made small notches on the edge at 5 gal increments.

Lastly, make a backup stick, just in case;)

And, remember there is a term for pilots who plan for flying to fuel minimums---------they become known as statistics.
 
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I too, am just starting my fuel tanks in my RV 10 and I am going to stick with the stock floats that Van’s sells. My research has shown in my opinion that I am over thinking it for the capacitive system. Simpler is usually always better.
 
Once again

If i was to build another set of tanks, i would install a second sender at the tip rib. This way a modern EFIS computer can be calibrated to measure fuel right up to the top, and to the very bottom.
 
I too, am just starting my fuel tanks in my RV 10 and I am going to stick with the stock floats that Van’s sells. My research has shown in my opinion that I am over thinking it for the capacitive system. Simpler is usually always better.


I agree, simple is typically better, but not reading fuel from 30G to 21G per tank really frustrated me. Also turns with some Gs screwed up the reading and it would "stabilize" some minutes after straight and level.

I have had both, today I have the CIES sensors and they are very accurate, I don't switch tanks on time anymore, the reading on those are .01 of a gallon accurate, way more than we need for the reading. And the reading is from Full to Empty. I have them on the ER tanks but I would do them regardless of ER or not.

Something to consider.
 
I agree, simple is typically better, but not reading fuel from 30G to 21G per tank really frustrated me. Also turns with some Gs screwed up the reading and it would "stabilize" some minutes after straight and level.

I have had both, today I have the CIES sensors and they are very accurate, I don't switch tanks on time anymore, the reading on those are .01 of a gallon accurate, way more than we need for the reading. And the reading is from Full to Empty. I have them on the ER tanks but I would do them regardless of ER or not.

Something to consider.

And imagine with ER tanks and 41.5 gallons per side how long it would take for the inboard sensor to start reading.

If I were building SB wings, the ER tanks would be a no-brainer in my view. A bit more complicated on QB or finished wings, but Ken’s kit and instructions are really detailed.

Nir, was that your RV-10 at Synergy Air South getting the ER tank mod? Nice plane!
 
I too am doing Ken’s ER tanks with duel CiES senders on my -14 build. I’m getting QB wings, so completed tanks will come with my wings. I’m sure I’ll be able to sell the QB tanks to someone that doesn’t want to fool around with the mess.
 
I am finishing up my standard tanks that came with my wing kit and will be selling these because I just now made the decision to purchase the extended range tanks. I figured I would do this instead of sending back the skins and the baffle to vans.

Can anybody provide me with information on the capacitative system that would maybe change my mind…. I would like the most accurate field measurements as possible.
 
I had Capacitive plates in my RV7.
1000h with no issues at all. I really have no idea what sort of smoothing algorithm was built into them but they were always rock solid and relatively "accurate"
In reality nobody puts tick marks on their EFIS every gallon so its kind of irrelevant how accurate they are for this purpose as you're planning and FF totalizer is of much more use - and likely safer. My refills are accurate to within 1/4 Gal mostly, and always within 1/2.

With my RV10 I have resistive floats. They are fine, except for the obvious fact they don't measure the top 5 gallons or so. Even though it irritates me, in practice it makes no difference to the way I operate the aircraft, and I've long since forgotten about it.

I too am currently building a set of ER tanks and will put 4 SW resistive senders in them. Mainly because they are cheap. I don't believe theres any real world difference between the "accuracy" of the Cies magnetic sweep and the SW and certainly not enough to pay 10x for them.

Good luck!
 
Sky Design ER tanks RV10 sender

I was speaking with Ken who was an engineer on the RV10. He also made the RV10 ER tanks which I purchased. I was debating between the CiES fuel senders and the Stewart Werner. I know the CiES are more accurate but is it worth the extra 2K?! I spoke to Ken himself and he said I can run dual SW fuel senders in each tank. I am still doing more research but I will update as I make progress. Just wanted to share with other builders.

Happy Holidays to Everyone:)
 
And imagine with ER tanks and 41.5 gallons per side how long it would take for the inboard sensor to start reading.

If I were building SB wings, the ER tanks would be a no-brainer in my view. A bit more complicated on QB or finished wings, but Ken’s kit and instructions are really detailed.

Nir, was that your RV-10 at Synergy Air South getting the ER tank mod? Nice plane!

Hi Krea,

I apologize for the late reply, I just noticed it.

Yes that was me, thanks for the compliment, I enjoy that setup. You can always change to ER. I actually did a retrofit to my plane.

Nir
 
I agree, simple is typically better, but not reading fuel from 30G to 21G per tank really frustrated me. Also turns with some Gs screwed up the reading and it would "stabilize" some minutes after straight and level.
.

Something not quite right here:
1. My inboard floats start to read below 25 gal, not 21 gal.
2. Coordinated turns shouldn’t adversely affect the float readings.
 
I am building an F1 Rocket with the optional Harmon 58 gallon long range fuel tanks and installed two Stewart Warner float sending units in each tank. In addition to the Van's standard inboard location, I installed the second one on the most outboard rib. Other than testing the resistance of each sender, I have not yet tested this modification on a MFD for calibration and accuracy.
 
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As I recall, the standard Stewart warner sending units have one lead affixed to ground. To use two of them in series, you need to modify one of them to remove the ground and bring it outside the tank using a sealed feed thru. When using two floats, they need to be wired in series to work properly as an integral and linear reading sensor.
 
What Bill said is correct, if you want a linear sensor. Of course, with wing dihedral you don’t get a linear response anyway. Most modern efis units will let you put in multiple calibration points. If you are using one for fuel readout, just wire the sensors in the usual way (both sensors grounded), feed the efis with both sensor outputs running thru series resistors (to average the readings), and use a few extra calibration points at near full and near empty.
 
I was wondering how you would wire the senders to work.. some planes have multiple senders, bonanza I believe and the Varga Kachina to name a few.. would the EFIS be able to calibrate the senders just hooked up on parallel? Or do you HAVE to modify one to wire in series?
 
For the Dynon EFIS, the two fuel level senders need to be wired in series, per Dynon. Others may vary.
 
Are the fuel senders that Van's sell for $46 good enough? Cies want $605 per sender which is a whopping 13x the money! Are they 13x as good?
I understand that you will have issues with the first few gallons due to the dihedral wings with either the Stewart Warner or Cies senders, and some people have added in a second set of sensor per wing to measure it properly.
Has anyone done two Stewart Warner senders in their stock RV10 fuel tanks to get accurate fuel measurements?
 
I’ve been really impressed with the accuracy and repeatability of the stock SW sensors and the EFIS calibration process. They are accurate and repeatable a fraction of a gallon through the whole range with no change over a year (1st year of operation). They seem so fragile but seem to work.

Edit
I have an RV8 not a 10 sorry
 
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