Building a Javron Cub

Here are the fuel lines in a stock Super Cub.



With the line run on the outside your wing root panel will not fit flush and you put a weird curve in the 1/2" 90 degree bend of your aft wing root fairing. You can see the holes where the fairing screws on. Don't ask me why this all stands out for me. 8)

Thanks Steve, great photos and info.

Bill

If you have your flaps extended inboard, The wing root panels don't go nearly as far back. Then you just have to massage the shape to fit around the odd shape created by the fuel line. Some of the rubber welt used in the landing/taxi light assemblies placed on the edge will keep the fairing from rubbing through the fabric.

Gents

Taking all your helpful comments into the hangar, I did a little experimentation today. Here is a little trick that you might find useful. Take an old bed sheet and some spring clamps and stretch it tightly over the part where you want to see how the lines of the fabric will lay.

Here you can see where I think the wing trailing edge will lie and where I will have a slight bulge under the fabric. You can see the shadow here of the fuel line. Once painted white it will be very hard to see. I am comfortable with this.





As you can see it fades out as the fabric is lifted away from the fuel line by the stringers and other structure just past the small vertical "C" channel.



This is the other side. It remains inside the fabric.



There will be a short print on the inside of my headliner until it goes behind the side wall.



I am not saying anyone should do it this way, just trying to give you things to look for and consider as you do your own build. If you are using a metal headliner all the fuel lines will run inside like the pictures above from Steve Pierce, then the metal headliner will cover them.

Here is what a paper interior pattern looks like when under construction.



Hope this helps

Bill

Running fuel lines anywhere close to outside fabic/fairings/structure in the prop wash area is a really bad idea. I'd run them inside the structure like Piper did to keep them protected.

Joints like this that are hidden between a ceconite headliner and the exterior fabric with no way to access them should be avoided. Move the joint back and around the corner to the section that crosses the fuse where the header tank would normally be. That way you have access from the upper baggage area. Also I would use a flexible connection like Piper did with hose and clamps instead of an "AN" fitting. Either way if you have trouble with a fuel line you'll be cutting fabric to replace it. Make sure to pressure test the fuel system before covering. Also make sure your flap cable will clear the fuel line.


Jason

...and if you're shooting for perfection and long term service.........etch, alodine, and epoxy prime those aluminum fuel lines.

...seen plenty of them with tiny pinholes from corrosion...Plenty of 'em. .....seems like usually Cessna's, though. Probably Cubs get new fuel lines every cover/20years. Cessna lines have been in there since the 50's, 60,'s, and 70's.

Gents

Taking into consideration the good suggestions from Mark and Jason I have rerouted the right rear fuel line inside and also put the joint in an accessible location. It now looks like this.....



And the joint will be accessible from the upper baggage area.....




Here is another thought. Craigs list. Watch it daily and you can find some great deals on tools. I picked up this 52" foot shear a couple of weeks ago. It needed a little clean up but it has a good blade and makes very nice clean cuts. You do not need one to build a Cub but you can find all sorts of stuff if you look.



Another thought.... I got this tripod and really like it. It is a Slik. It is light weight, folds up pretty small and it will hold all of the smaller digital cameras just fine and even a 35mm style as long as you are not using a monster Binford 5000 telephoto lens. Great for camping etc. It is a full size unit, not one of the table top or clamp on shorties. I have been very pleased with it. My last one went down the river so I got another just like it.





It makes it a little easier to take a few photos like this to prove to the FAA that you really did build the airplane.




More random thoughts. The Dremel moto tool is something that is really handy and you will probably use it a bunch. Be sure to get a variable speed unit. The Dremel I got as a teenager for building models finally bit the dust after 40 years (man, ya just can't get good stuff anymore, nothing lasts, heck it was barely out of warranty ;-)) so I had to replace it. If this one is still working 40 years from now I'll will it to my son.



Tip - you can drill through a nutplate. A #40 drill bit will fit in a #6 nut plate without hitting the threads (much) and if you are careful you can drill from the backside to locate screw holes. The hole will have to be enlarged for a #6 screw but it can be really handy to get the hole in exactly the right place. You can also use a variety of hole finder tools but this technique might help.

Nutplate.......



Drilling through the nutplate, be careful to go straight so you do not damage the threads in the nutplate.....




Hope this helps

Bill

Bill Rusk said:

Tip - you can drill through a nutplate. A #40 drill bit will fit in a #6 nut plate without hitting the threads (much) and if you are careful you can drill from the backside to locate screw holes. The hole will have to be enlarged for a #6 screw but it can be really handy to get the hole in exactly the right place. You can also use a variety of hole finder tools but this technique might help.

Nutplate.......

Drilling through the nutplate, be careful to go straight so you do not damage the threads in the nutplate.....

Hope this helps

Bill

Click to expand...

I know it's too late at this stage, but if you build your interior before installing the nutplates, you can drill the #40 pilot hole through both the tab and panel at the same time.

You can also sand/grind some of the twist off about 1/16" up the twist to narrow and dull it because all you are using in sheet stock is the tip. Less chance to get the threads.

Glenn

Great to see your progress, Bill. I'm still patiently searching for a good PA-18-95. Sometimes I wish I would have spent the past year building one instead of trying to buy one.

I agree that craigslist can be an excellent source for used tools. But you do have to keep on top of it - the good stuff goes fast. I use Google Reader to aggregate RSS feeds containing craigslist search results. It's easy to see at a glance if anything new pops up.

The Dremel sure is handy. I already have a bunch of Milwaukee M12 cordless tools, so I went with their dremel-like offering. Definitely recommended. I also picked up a little router jig that the dremel screws into. It's meant for guitar building, but it worked perfectly for trimming the plywood gussets off of my Pietenpol ribs.

Roto Zip works great for holes of all shapes in AL sheet.

Glenn

Great ideas and suggestions guys.

Someone asked about welding in tubing for the upper stringers. It is a fairly common mod up in Alaska. As best I can tell from a calculated standpoint (Vs actually weighing it) the weight penalty will be about 18oz. The top three stringers (using Univair stringers like in my build shown previously in this thread) are 113" long for the top two outside stringers at 12.85oz each and the center is 110" at 13.81oz for a total of 336 inches weighing 38.49oz. The equivalent tubing of 3/8 .035 will weigh 56.8 oz. according to the Acft Spruce catalog. Hope this helps John

Bill

Bill, Here is how I did mine. I used adel clamps on everything and I can get to all of the fittings. Has worked perfectly for over 100hrs. Don

Dave Calkins said:

...and if you're shooting for perfection and long term service.........etch, alodine, and epoxy prime those aluminum fuel lines....

Click to expand...

thats also why i Use the strait HARD anodized fuel lines reeve sells, it has the protective coating on/in it, instead of the soft pure uncoated, rolled tubing....

someday I want to get set up for anodizing, but the shipping issues for the caustics to alaska has been an issue...
http://www.caswellplating.com/standard-anodizing-kit.html

Don, nice looking installation.
Mike - I use the straight stuff too, but didn't know about the finish. The coiled stuff is a pain to get straight. Thanks

Bill

mike mcs repair said:

thats also why i Use the strait HARD anodized fuel lines reeve sells, it has the protective coating on/in it, instead of the soft pure uncoated, rolled tubing....

Click to expand...

Isn't the "protective coating" pure aluminum over the alloy or are you talking about something else? Alloys corrode thats why they plate them with pure al. I used to use the hard plated tubes just "cuz" till I noticed they seem to corrode faster, don't know if they react more with fuel or what, (I don't think they plate the inside). Went back to staight aluminum tube for fuel and save the alloy for high pressure hydraulics.

Plenty of the corroded old Cessna fuel lines are corroded from the inside out. Most of them that I've seen are so.

These days, I get a warm fuzzy from etch, alodine, and priming lines on the outside.

But that won't help inside-out corrosion, just like anodizing won't help.

Bill, I'm glad to see you re-routed that line.

That was kindof bothering me.

Someone mentioned using titanium tailwheel spring. I used a 5/8" solid titanium rod on my in progress 1320 GW cub. For
heavier gross weights maybe 3/4" would work better. Online metals sells the rod.


Jim Miller

Bill Rusk said:

Great ideas and suggestions guys.

Someone asked about welding in tubing for the upper stringers. It is a fairly common mod up in Alaska. As best I can tell from a calculated standpoint (Vs actually weighing it) the weight penalty will be about 18oz. The top three stringers (using Univair stringers like in my build shown previously in this thread) are 113" long for the top two outside stringers at 12.85oz each and the center is 110" at 13.81oz for a total of 336 inches weighing 38.49oz. The equivalent tubing of 3/8 .035 will weigh 56.8 oz. according to the Acft Spruce catalog. Hope this helps John

Bill

Click to expand...

Nice data about the stringers.

But anyone ever try not putting any side and botom stringers?? I wonder what it would look like...

Folks

Here are a few more photos and notes. Still pretty much working on the interior stuff.



I am making a panel, removable, to block off the extended baggage when not in use. The idea is to effectively make the cabin smaller so the heater will work better in the winter.


I had Jay weld in a couple of attachment tabs for this.


Beginning of the side panel fabrication for the three piece boot cowl.



I'll go borrow a set of rollers tomorrow to get the lower curve in.



Unfortunately, as sure as the sun will rise tomorrow, at some point during your build you are going to drill a hole or two in the wrong place. Here is one technique for fixing it. I drill a countersink bevel (even on thin stuff), coat a clipped rivet head with JB weld, and basically glue it in the hole. Then a little sanding, filing, grinding or whatever and you have a pretty good fix. Another coat of JB weld over the top, sanded down and it comes out pretty smooth.


Often you will need to sand the back side as well so a panel will fit up flush and it will look like this. A Dremel tool helps here. I know some folks just bondo over the hole and that seems to work but I feel better with a little more substance in there.




Because I had to box the rudder cables (due to the floorboards laying on the longerons) I needed a way to secure the bottom of the side panels so that cargo would not collapse them into the cables. Good old epoxy. Use 80 grit sandpaper to rough up the aluminum and also the carbon fiber floorboard. Cleaned well with acetone and glued in a couple of angles with nutplates.


I like a fabric interior on my panels. Feels warm, reduces noise, and looks nice (to me) so I use Weldwood Contact Cement to glue a med weight, tweed type fabric to the side panels. This will add about 3 pounds to the weight Vs nothing. I do not know how much paint, or flocking, or other finishes would add. It will be less than the last build as I am not doing the extended baggage area like the last time. The extended baggage will be left in the natural carbon fiber. This side panel weighed 13. 21 ounces pre fabric and 18.72 after fabric, so the weight penalty on this panel was 5.5oz.



This is the back side. I wrap the fabric around.



Once it is covered use your soldering iron to burn out the screw attachment holes. You can also use the soldering iron to melt down any frayed edges. It works like burning the end of a rope to cut down on fraying. Works great and leaves a nice looking, clean hole.



The installed panel. I will paint the attach screw heads flat black and that will help them to blend in.

Hope this helps

Bill

Olibuilt said:

Nice data about the stringers.

But anyone ever try not putting any side and botom stringers?? I wonder what it would look like...

Click to expand...

You would have fabric beating against every tube in the fuse. You'd either have to tape along every tube or recover in 78 hours.

Nice looking interior!

Bill, great work, I love reading your updates and seeing the pictures. You do a great job with it, very instructional. Keep up the great work. You will be flying in no time!

New pool: $1.00 per entry-

What place will this plane take at OshKosh competition????

This is a piece of art, not a working cub!

Clay Hammond said:

You would have fabric beating against every tube in the fuse. You'd either have to tape along every tube or recover in 78 hours.

Click to expand...

I think the Pa15 was stringerless. This is a 17



Glenn

Hi Bill great looking interior where do you get the fabric for the panels what is it called? I'm going to put it on mine I'm starting to make my interior panels now.

Thanks BRYAN

Olibuilt said:

Nice data about the stringers.

But anyone ever try not putting any side and botom stringers?? I wonder what it would look like...

Click to expand...

Clay Hammond said:

You would have fabric beating against every tube in the fuse. You'd either have to tape along every tube or recover in 78 hours.

Click to expand...

The stringers keep the fabric away from the tubing so that water and other debris does not collect making corrosion traps.

Glenn,
Actually two stringers on each side of a PA-15. Follow the bottom of the window back
and where the rear door edge goes from vertical to diagonal. Most people do a belly stringer on
rebuild.
Dave