Fuel level indicator and fuel tank fittings

[Jeff XL79]

I'm at the point where I need to decide on the method for indicating fuel level. I've built out the first bay and supported the structures that will carry the weight of the tank and fuel. It was done by doubling the second rib to be like the root rib. The entire bay was lined with thin carbon fiber sheets to spread the load across all surfaces. Then I riveted an inch and a quarter aluminum angle all along the bottom of the bay. The diagonal was also sheeted and the area behind it was also lined an supported in the same way. This gave me the additional triangular space only two inches shallower. 
The tank has been built out of divinycell foam and is fit to the bay. Before I put the top on the tank I've got to decide on having a fuel level indicator or not. The most obvious choice would be to install a high and low 90 degree elbow with a sight tube. The downside would be more holes that could leak. I've also looked at Radiant's fuel level system but I'm not sure if it will work in my odd shaped tank. The outlet will be back where the diagonal meets the rear root fitting.
I plan on using aircraft spruce finger strainer and the weldable flange to get the fuel out. I'm not sure what fittings to use for the sight gauge.  The home depot sink drain has been purchased but I'm not optimistic about it's sturdiness. I'd like to see some options. I'll attach some pictures as soon as I can get to the shop.

Jeff

[Jeff XL79]

Divinycell box.

[Jeff XL79]

Carbon fiber box.

[Jeff XL79]

Divinycell shell.

[Jeff XL79]

More angles. The lip around the top is 1/4" deep. I'll put a flox mixture around the top as I do the last vinyl-ester coat. Then I'll let it cure upside down with tape securing the seam. Zero leaks is the goal. I need to button the tank up ASAP because my vinyl-ester has two months left. Eek!

[Jeff XL79]

I just looked up the Radiant fuel gauge again. It's now about $250! Yikes. Sight tube it is. Plus you would still have to buy the sensor . 
There is a sensor and gauge combo on Amazon for about $75. Downside is having the outlet and wiring exposed on the top of the tank.

[Kamcoman77]

Jeff, your tank looks great! My tank is one layer of 1/4" Divinycell foam. It is sealed inside with two coats of vinyl-ester resin and all seams were sealed with resin/flox fillets. Top is secured similar to your idea. Seems very strong. I have plates installed for a front and rear fuel outlet, with a quick drain in the rear. Only using a plug in the front for now, since I may not need dual outlets. I put two 90° nipples in the side for my sight gauge, sealed with resin/flox. Exterior covered with bi-directional fiberglass and epoxy resin. Don't see much chance of it leaking. I put two extra diagonal 3/4"x3/4" pieces of spruce between the ribs 1, 2 & 3. I did not feel a solid base was needed after test fitting.

[Jeff XL79]

Looks very nice. We're thinking along the same lines.  I actually took inspiration from your design for my tank. My wife reminded me that I overbuild everything and I think she's right. I'll also have to install my fittings after the tank is final installed otherwise i couldn't get it in.

Did you just solder in 1/4" npt fittings to a plate or is there a ready made product? I was going to use the aluminum flanges AS sells. I was going to use 3,  two for the sight gauge one for the outlet. 

Jeff

[Kamcoman77]

The 1/4" aluminum plates were sealed into the foam with VE resin/flox. They were covered over with the fiberglass/epoxy outside covering. The fittings just screwed into the plates since the holes are taper threaded.

[Jeff XL79]

Your fuel shutoff valves look like motorcycle petcocks. I was looking at those and hadn't found a source besides Amazon.  Where did you find yours?

[okdonn]

This gauge requires electricity, but I like the idea of it. I bought one for the weird shaped tank for our Woody's Pusher. I haven't finished the tank yet, so YMMV.

https://www.lskelectronics.com/store/FuelGaugePro-Analog-Panel-Gauge-Kit-p286783482

[Chuck in Indiana]

Your fuel shutoff valves look like motorcycle petcocks. I was looking at those and hadn't found a source besides Amazon.  Where did you find yours?

Of course, I've a Guzzi Guy, but MGcycle.com will have them. Cheesehead and Gordon are good guys..

[Kamcoman77]

The fuel valves I originally bought were from eBay. The rear Harley Sportster valve did not flow as much as I liked so I bought one from Throttle Addiction. It flowed almost twice what the Harley valve flowed.

[Jeff XL79]

I received the finger strainer and the aluminum weldable flange from Aircraft Spruce.  The threads are not even close to fitting correctly. The flange side looks like a straight pipe thread but the finger strainer side is a tapered npt style thread that isn't even close to fitting. I'm going to have to run a die over the strainer just to make it close. Very disappointed in AS. I'll call them on Monday but I don't think they'll have an answer.  

All I need is a plate that can have a 1/4" npt female fitting soldered in. So, I'm going to have to make the plates . I'll go to Amazon and get some fittings with a suitable flange and size and forget about AS.
Nothing like starting over to come up with solutions. 

Jeff

[Brock]

Might be able to use an OOPS fitting for the threads.  Could work in just the fiberglass.  These are standard for the sonex polyetheline tanks.  Can be retrofited easily.

https://www.sonexaircraft.com/eshop/cart.php?target=product&product_id=16742