LE and XL Fuel System

[PropMan]

I'm workin on the fuel system for the XLR an thought i'd share what has been learned so far. Hope those who know better than me jump in and help straighten out any screw ups.
Going to post several pictures of progress.

After reading the plans i decided to build a tank from aluminium, similar to my RV6 wing tank in technique(rivets and pro-seal).
The tank will reside in the left wing, additional support has been added to the upper ribs where the tank will attach. (and to the right -Just In Case(-: )
Plan is to form ribs that have the upper rib shape and the top of the tank will be upper wing skin in that area.
I first read what was available on experimental fuel systems , then sketched out what i thought would work for My installation.

edit: you will notice I have a header tank in the design. that is due primarily to the type of carburetor on the Scarlett 3VW. it is a Walbro 37, and has no bowl.
my thought process is to make Sure i have fuel at all times, and to limit chances of air in the fuel lines.

[PropMan]

I then made form blocks to fit the rib bay, where i wanted the tank to reside. calculated to make sure i had 5 gallons of Usable fuel.
Cut my aluminium sheet and formed a couple ribs.
The forming causes the rib to have a curve, it needs to be fluted in the proper spaces, rivet spacing is determined the flutes are done to straighten the rib.

[PropMan]

Ribs complete, so i cut a sheet the proper width and took it to the brake.
Carefully measured and made my bends. 
The flanges will be trimmed and top fabbed up after i sort out plumbing.

[Steve]

Ribs complete, so i cut a sheet the proper width and took it to the brake.
Carefully measured and made my bends.
The flanges will be trimmed and top fabbed up after i sort out plumbing.

N i c e !:emoji_u1f60e:

[Jim B]

Propman
Looks great.  What is your rivet spacing?  Do you apply the proseal during the construction or after the tank is complete?
Jim

[PropMan]

Propman
Looks great.  What is your rivet spacing?  Do you apply the proseal during the construction or after the tank is complete?
Jim

The rivet spacing is 1 1/8" , rivets are AN470-3 and AN426-3, of proper length for the application. The top skin will use the flush rivets(AN426). The proseal is applied liberally along the rivet line during assembly and I will also form a fillet on the inside of the seam. i'll post photos when to that stage of assembly.

[Tom H]

Frank, that will be a slick installation.  Will you have any support for the top panel to keep its shape, or will the curve take care of that?  I know from welding tanks that the panels will get distorted, but have not done a riveted tank.

I'm sure you have it planned, but your sketch does not show a main tank vent.  Maybe part of the filler cap?

We have the Verner on LEU Treehugger, nea, Three Jugger, fed directly from the wing tank.  Starts and runs fine.  We plan to do a fuel flow test into a container to verify adequate fuel flow, especially in a nose high and/or low fuel level condition.  Then we plan to do a full throttle run-up when nose high to simulate a worse-case (or, maybe it is best-case with that awesome prop) climb condition.

When you eventually test it, it will be good to know if the Verner will run with a low mounted header tank, like you have, with worse case low/no fuel in main tank.

[scottiniowa]

Looks like Frank is doing excellent work there.  Some may wonder about a NO pro-seal method using welded over rivets and that can work to, but takes perhaps what might be considered special skills on the welding side…   It is simply a learned “skill”  Just like many other aspects of the aircraft build.

That being said, many ways to skin the cat, and Frank’s sure looks good!

Frank, did you calculate volume?   I  could always do that for you, with a few measurements, doesn’t take long.

cheers
Scott

[Jim B]

Prpoman
Thanks for the info.  I am keenly interested in the outcome of your tank.  Looking forward to more pictures and progress.
Jim

[PropMan]

Tom- if all goes to plan the top skin will be supported by the ribs and possibly a strip of angle down the center formed as the ribs were with the curve. And, Yes, the cap has a vent, pic to follow.

Scott- I have all the tools to weld , just haven't had time to acquire the skill. so opted for something i knew. One day i will tho. 
Yes, i calculated the volume ,old school way. i may send you the dimension just to check my work, Thanks.

And Scott hit the nail on the head, many ways to skin this cat. just pick one you are comfortable with and go. the basic fuel system stays the same, just lots of ways to build it.

[PropMan]

Here is a shot of the fuel cap.

I want to keep things as aerodynamic as possible, read drag reduction. and my way is not always the best. just how i decided to do it. I purchased the cap from ACS- UD-3-C Fuel Cap with Contoured Adaptor. drilled and installed vent tube and a few vent holes inside cap assembly.

[PropMan]

Had a little time to work on the fuel tank today.
Drilled the ribs to the bottom skin and drilled a couple stiffeners to the tank bottom to give a bit of support. 
Also test fit the tank in the wing to determine where trimming needs to be done.

[Steve]

N i c e

[Poorman2]

Looking good Frank! I see you are using 2024-T3. What thickness are you using?

[Bob Wood]

Frank,
Looks really good, what is your estimate on weight?