Building a Javron Cub

All screws have nutplates. The screw on the far left in the photo is nutplated to the fairing. The concept is that most nutplates are into some form of structure, like a wing rib for instance, but there are places where two fairings are screwed together, so you will have a few nutplates that are attached to the fairing pieces themselves.


This small aft underside fairing has two nutplates on the fuselage edge side. One at the front and one at the wing trailing edge.



Masking tape will hold the flap gap fairing in place while you drill the screw holes. Works great. I put the screws 3/8" from edges with about a 6 1/4 inch spacing. That is what it took on my set up to make them equally spaced. Yours may be slightly different but this should give you a starting point. The screws on the wing top are 1/2" from the trailing edge, thus the forward edge of the fairing is 7/8" forward of the wing T.E. The screws on the bottom (in the cove) are the same spacing and the depth is whatever it takes to bring the fairing down to about 1/8" gap above the flap.


Lots of ways to do the wing root fairings. I find myself looking at photos of other cubs and trying to figure out how I want to do mine. I have found it REALLY helpful to have lots of photos from other Cubs to look at to figure out how others have solved problems. You see, building an airplane..........

"It's just a series of problems to be solved"

But it took a while for me to figure out how to take the pictures of other Cubs. You must get up close, and take pictures of joints. Where the rudder pedals go in to the floor, how the interior panels overlap, etc. DETAILED photos will be a real asset. So when you go to a fly-in, take a couple of hundred photos, but get in close to get the specific details. You will refer to these photos over and over again. I can't stress this enough. Get a huge pile of detailed photos. Also, if you have not found it yet, there is a massive index on the first post of this thread.

Hope this helps

Bill

I drilled with a #43 and tapped with a 4-40. for this window trim.



This window trim piece is bent back sharply on itself then wedged between the fuselage and the window channel.



There are no fasteners for this piece. It is held in place by friction fit and other trim pieces that "capture" it.



Looks like this when done



Here is a tip. Get a headlamp. Sometimes you need a little extra light to see down in a hole or something but don't have an extra hand to hold a flashlight. Once you put this in your tool box you will be surprised how often you use it.



I remade this windshield trim strip. If you scroll up a little you can see a picture of the previous version. The weld seam between the fuselage structure and the window channel was visible. By making the trim piece a little wider it covers that seam. Once it is painted white I think it will look a little nicer.



So, my neighbor and friend Jim stopped by to check on the progress. Jim is an A&P IA and owns a NICE Legend Cub, along with several other cool airplanes, including an awesome C-180, and he helped with the last build. So after a couple of minutes visiting.....he got put to work. Haha....notice the trend here. You come to visit, you will probably get put to work. He made the pattern and is cutting the rough draft of the forward wing root fairing. Thank you Jim!


After Jim went home, I started bending and trimming, and got one of the forward fairings mostly fit into place. Completing the forward fairings will be todays project.

Hope this helps

Bill

Bill, you're in the nothing left to do but finish stage hope to see you and your bird soon...New Holstein? Kirby

Thanks for asking Kirby. Actually pushing for Johnson Creek. I admit that may be optimistic but you have to have a goal. After JC I hope to get the float install done, so NH may be on wheels, floats, or not at all if I'm at the halfway point. Hope to be at NH. Look forward to seeing you there.

Bill

My hope too, tell you what you make JC and I'll bring the drool towels...

Thanks Kirby. I'm not too worried about drool towels, I just hope they don't laugh too much.


Forward Wing Root Fairings



As mentioned earlier in this thread, you can use a table saw stand to do some rolling. By rolling it back and forth and pressing with your hand you can roll a curve in the sheet aluminum.



Then when I needed a little sharper radius I found a piece of 4130 tubbing. Start at the top and work your way down and around. Put a little mark where you need a little more bend.



Then I found a smaller tube on the brake when I needed a tighter radius again. Springback is a pain sometimes. Just keep working it. It probably took about 20 plus bends, trial fits, more bends, etc.



Then you can use your smooth jaw pliers to make a very slight edge break, in just a small area, where it is not laying flat.



And when you are done it should fit pretty nice.



Another view of the top side.

When you are all done with the fabrication you will use/need........

Univair 415-31130-10 Rubber moulding - used between wing root fairings and windshield. Comes in 10' length but you will use 2 pieces about 24" long each so you will have plenty left over (or you can split it with another builder).


Hope this helps

Bill

Bill, i struggle finding those holes for the top fairing, especially the ones where theres no tank and the fabric pulls the rib a little from straight to not being straight. Some use a univair rib there for its wide flange area, i didnt see on jays ribs how yours ended up on the top there. When you remove that top wing root fairing could you take a picture there of the top of the butt rib? Im sure you will have some, and others will on tips and tricks especially when the tanks in on things that go on under that top butt rib wing root fairing? Was also going to ask if i could see how you finished up your tubing on top to go with a half sky lite? Hope you dont mind? doug

Doug
I will get it when I get home, might be a couple of days. Glad to help if I can.

Bill

Doug

Hopefully this will help.



I ended the fabric at the middle of the skylight. Be careful not to over shrink the fabric here as that center "C" channel will bow. You can also see the nutplate in the "C" channel for the skylight plexiglass.



Another view.



This is where it gets a little weird. I actually ended the fuselage fabric in the normal place for a full skylight, then just added a piece for the half skylight that I covered. I did this so that, if I decided later that I really missed the full skylight, I could just carefully cut out that piece of fabric, without disturbing the fuselage fabric, and then install the full skylight. I hedged my bets, if you will. There is a tape at the seam (there would be a tape there anyway) so it had no adverse affect on appearance. I also installed nutplates there. You can see the seam/joint a little here. The round black thing in the right part of the photo is the shoulder harness inertial reel.



This is the top of the butt rib. Javron installed the #10 floating nutplates (probably right off the Piper Drawings). I do not know if he is doing that on all wings. I got the prototype set of wings so there may be some differences.



Underside of the butt rib. Nutplates are on about a 7 inch spacing.



Underside of the tank bay rib with fabric wrap. this rib will bow a little. You can use a little safety wire to wire it straight before cover to help keep it straight, then remove the wire after cover and paint. Also do not drill these holes in the tank cover until after cover and paint so you can accommodate the bow.

Hope this helps.



Picked up my Sutton exhaust last week. This part weighs 147.3oz for the standard muffler and 166.5 for the "high heat" version. They weld in extra metal fins for extra surface area to get more thermal transfer, thus higher heat output. About 20 oz heavier.



All the other stuff weighs 49oz so the total for the high heat system is 216.5 or about 13.6 pounds. The Vetterman system may well be lighter. I am not sure, you would need all the heat muffs etc to make an apples to apples comparison.



Although I purchased the system from Sutton, I worked directly with the manufacturer to see if we could make it lighter. This was the third and final attempt to make it out of Titanium. We tried standard titanium, normalized, and finally heat treating, but were unable to make it work out. It would crack at the welds when expanded. Now before all you metallurgist get your panties in a wad, we know that we could redesign the muffler to make the titanium work, but that was/is not an option. That gets into unethical, and quite possibly illegal, territory. This is a Sutton system. Made their way. We thought we might be able to make it using titanium in places to save weight, and I "Okayed" this with Brian, but redesigning the muffler is another whole ball of wax and I was not comfortable doing so.


So........there ya go. Just thought you might like to know, we tried using titanium, but in this specific case and circumstance, it did not work out. This is the fun part of building an "experimental" airplane.

Hope this helps....


Bill

A lot of obscure and very detailed information, necessary to build an airplane, is not just time consuming but expensive to aquire, as your titanium trial with the exhaust shows. Now, we have that knowledge.

Folks

I had a couple of unexpected (but definitely not unwelcome) guests last evening. jasimmons from the site and Splash stopped in and stayed the night.



jasimmons (on the right) with his recently purchased 2010 CC. Splash on the left. They were/are enroute from the purchase, and ferrying his new baby home to Idaho. We had a great visit and I got to meet a couple of great guys. jasimmons has been on the site here since about 2003. He used to own a PA-11. Now he is living large with a CC. Splash is a fighter pilot that is getting sucked into the dark side of off airport, backcountry flying, and ......."Another one Bites the Dust" .......Once hooked he will never be the same.



Managed to get him in the hangar but it was a mite tight. Three cubs, a set of floats, a paint booth, bathroom, and tools in a 50 x50.



Great fun......



And they're off. I had the pleasure of meeting a couple of great Cub pilots. Tailwinds gents. Hope to see you at Johnson Creek.

Bill

Apologies to the rest of the SC.orgers who are expecting to see Bill's Javron Cub at JC. I'm afraid our visit only slowed Bill down. Hope he and his cub still make it. The pictures and documentation on this thread, as good as they are, still don't do it justice. A true work of art. A true craftsman. And quite simply, a great guy. Thanks Bill.

Bill,

Why did you go with the bent exhaust over the straight? Was it just for easier lower cowl removal or are there other advantages?

Colin

Colin

That is just what came with it. The tailpipe comes off, which would facilitate lower cowl removal. The fit is close. I had to make a small cut on the rail to increase clearance. It was OK as is, it did not touch but I wanted a little extra clearance. Looks like this......





Hope this helps

Bill

These are my Randy Appling carbon fiber wing tank covers. Unfortunately the fabric pulled the outside tank bay rib a little and I had no edge distance for the middle holes on that left side above. So I made a little trim strip from .016 and used that to sandwich the edge of the tank cover. Once everything is painted white I don't think it will have an adverse appearance.



Perhaps you can see it better here.



Another hint/tip. It does not matter exactly where the cowl brace rod attaches but it needs to be 90 degrees to the motor mount tube. If it is not 90 it will walk until it is. In the process your cowl will try to move and it will be all out of kilter. It does not matter where it attaches to the cowl brace C channel, as long as it does not interfere with anything, but be sure it is 90 degrees to the motor mount tube.


Hope this helps


Bill

Bill,
Two thoughts.

Place a strip of anti chafe materiel between the tank cover extension and the fabric. There will be a lot of flexing of the fabric on the top of the wing.

That clamp on the cowl brace can be tight up against the cluster at the upper end of the mount tube which will eliminate any possibility of sliding.

skywagon8a said:

Bill,
Two thoughts.

Place a strip of anti chafe materiel between the tank cover extension and the fabric. There will be a lot of flexing of the fabric on the top of the wing.

That clamp on the cowl brace can be tight up against the cluster at the upper end of the mount tube which will eliminate any possibility of sliding.

Click to expand...

Wouldnt you want to keep the support rod as far away from the intake pipe as possible? Your cover deal looks fine but maybe randy would make you a cover thats a little wider, youve came to far with perfection, either way it dosent matter, maybe he should be making these covers a little extra wide and having the need to be trimmed? Are his covers all one size? Is trimming carbon fiber a easy task, just wondering, ive never done it. In my post 1393 you will note the few times ive been there i have always struggled with curved ribs after covering, this is more just a heads up to others to take note than anything.With a regular rib there isnt much room for fastners by not ending up straight.

tempdoug said:

Wouldnt you want to keep the support rod as far away from the intake pipe as possible?

Click to expand...

Yes, but as Bill noted "It does not matter where it attaches to the cowl brace C channel, as long as it does not interfere with anything," Just move the channel attachment a little further aft.

tempdoug

Thanks for your thoughts. Unfortunately, it is not easy to make a new CF tank cover. You have to make a mold first and that can take many many hours (weeks even, for someone who is just doing it part time). His cover was/is fine. The problem was me. I will post a picture when the paint dries and I think you will see that the solution will work well. I posted that as a hint to others, that if they end up in a similar situation, there is a relatively easy solution. I could have discarded the covers and made new ones from aluminum but that would have added weight and time. Building an airplane is just a series of problems to be solved. Problem - tank cover does not fit right. Solution - lots of different possible solutions. I chose this one. That is what makes this whole thing so interesting - seeing how others solve their building problems. Guys with tons of experience, tools, and knowledge might choose a different solution. A guy with lots of experience working with CF might have made new covers, or reworked these. I don't have those skills at this point (I might in the future) and so for me that particular solution is lower on the list of options.
And this paragraph is not really directed at you but to all potential builders, and readers of this thread, in general. There will be lots of "problems" as you build. You then mentally list all the possible "solutions" and then choose the one that fits best for you based on your pocketbook, skills, goals, etc. I have tried in this thread not to tell you how to do something (although I'm sure I have) but rather how "I" did it. If that works for someone, and helps them save time, do a better job, save money, etc. Great, then I have accomplished my objective. And I love all the inputs from others, as I, and everyone else learns other ideas and other thought/problem solving skills. If someone chooses a different solution, that is great too. One of the things I really enjoy about homebuilt airplanes is seeing the differences and creativity of the builder. What was their objective? How did they meet that? There are some absolutely AMAZING builders out there. I'm really not one of those guys, I just chose to write it all in a blog.
I sincerely appreciate yours and everyones posts. By your questions, others like Pete, Mike, Steve, Crash, etal post and we all learn. Thank You. Back to the hangar......(Thank the Lord it is still standing - dodged all the tornados a couple of days ago)

As always - Hope this helps....

Bill

Bill, gas tank covers and wing root fairings to rib attach, i never learn, did it 3 times in a row.:-x If my next wing ever does come again, there will be a univair rib there, just a nice big flange, unless i see a better idea? Like you say just problems to solve. I dont have the skill but am anxious to see what your solution is. And always remember this how peolple learn, i watch the neighbor skinning coyotes, a routine i bet no ones ever seen but the end product is unreal nice.

Just something for all to keep in mind. Fabric is shrunk taught to form a fairly stable surface all over a Cub airframe. In order for it to be taught, it needs to be pulling against something. This something needs to be stronger than the pull of the fabric. Consideration should be given to the structure of that something knowing that the fabric is going to try to overcome the strength of that something. A stock curved wing bow is shaped in a manner which opposes the pulling of the fabric yet has been known to damage structure at it's ends. A squared off wing tip or as in Bill's case the outboard rib of the gas tank bay will need considerable reinforcement to prevent bowing in the direction of the fabric. Sometimes just a wider flange will be enough. Other times diagonal braces may be needed, or both. Only experience will really tell you what is enough. You can test before covering by pushing against the part in question to see where and how much deformation takes place. Then reinforce accordingly.

Fabric has been known to destroy wing tip ribs, deform fuselage longerons, warp trailing edges (WW1 Spad) etc. Longerons are sometimes bowed out slightly, allowing the fabric to pull them back in line straight. Shrinking fabric is powerful and destructive stuff. Bill's rib seems to have just a small distortion, yet enough to change screw edge distance.

Bill can you also add the weight of those strips to my guess at at the ew of your plane or are we locked in on the chart?lol:lol:

Bill Rusk said:

..
1 Unfortunately the fabric pulled the outside tank bay rib a little and I had no edge distance for the middle holes on that left side above.


2 it does not matter exactly where the cowl brace rod attaches but it needs to be 90 degrees to the motor mount tube. If it is not 90 it will walk until it is.

not true, use the proper clamps, not those rubber covered adels....

Bill

Click to expand...

1 Use safety wire before shrinking, from tank rib holes to spar/compression strut to prevent that

2 not true, use the proper clamps, not those rubber covered adels....

Pete - Thank you, good input

Cub12 - sorry no changes (only cause I'm too lazy to update the chart) haha

Mike MCS repair - "2 not true, use the proper clamps, not those rubber covered adels" .... thanks, but what are the "proper" clamps?



The wing tank lid with the extra "oops" strip after paint. The strip added .9 oz with paint.



Need to paint the front edge of the tank cover to match stripe.



Cal helping install the tanks. I had to reposition the electronic tank probes from the side of the tank to the front. I will post more on that later.



The flap gap fairing/seal comes in 2 four foot long pieces. Jay was talking about doing them as one piece but I'm not so sure that is a great idea. Yes, it would look nice without the seam, but that would be a hard piece to handle without damaging it. It is soft aluminum due to the sharp bends, and it would be really easy to buckle it while sanding, drilling, trimming, painting etc. So....I'm OK with a two piece seal personally. But here is just one idea to make it look nicer. Mark epoxied a small piece of aluminum into the joint so that the ends would stay lined up at the seam.



Mark mixing the epoxy. His job this Saturday was putting the finished gap seals on.



The end result.



One of the things I found to be REALLY annoying and time consuming on the last build was removing the instrument panel. In order to do so all the push/pull cables had to be disconnected, zip ties cut off, threaded back through the firewall, more zip ties cut, then each had to be removed from the panel, then the panel could come out. This time I am putting the cables in a separate sub panel so the instrument panel can be removed without disconnecting all the cables.



The sub panel will screw in to the main instrument panel like this.



Something along the lines of this. There are lots of other ways to skin this cat but a sub panel will be super helpful for this part.
Just something to think about.


Hope this helps

Bill

Fuel Probes


Here is a link to my inputs on installing electronic fuel gauges, earlier in this thread (tome)

http://www.supercub.org/forum/showt...g-a-Javron-Cub&p=597941&viewfull=1#post597941



My original plan was to have the probe go in this extra bung (the left hole, welded in by Javron for that purpose) and then the probe would make a 90 degree bend and go down and aft. Unfortunately this plan had some serious issues. The probes I got are not made to be bent. You must get the bendable probes, then they can only be bent a certain way and radius. Then that bend has to fit through the bung (think radius again) then you have to use a double compression fitting on the install because you can not rotate the probe after it is in the tank. It just got too complicated.



So I had another bung welded on the front of the tank. Now the probe angles down and aft in a straight line. Easier to install and less likely to mess up the probe while bending it. I think this will work better. In this location it does not interfere with the aileron cable or tank lid. To get the whole story on this, and the logic behind installing electronic fuel gauges, go to the link above.


Hope this helps

Bill

Bill, I have a question, I am installing the skylight and windscreeen right now and have looked at a lot of pictures but can not determine the proper way. It looks to me that the windscreen must overlap the skylight and the same aluminum strip covers both. The screws actually go through both the windscreen and the skylight. The problem I have with this is, it leaves a step because of the thickness of the skylight you end up with a gap between the aluminum strip and the skylight on the backside facing aft. Am I missing something or is this just the way it is.

Thank you

Greg

Greg

yes the windscreen goes over the skylight and it does create a "step". When you break the aft edge of the trim piece, instead of the usual 1/8 to 3/16 break it will be closer to 3/8 or even 1/2"

hope this helps

Bill

Bill, It will probably leave the wing fairing with a little gap over the skylight in the upper corner on each side this way. I figured that is what it was but I also thought maybe there was a better way.

Thank you

Greg

Mauleguy, look at the photos in post #1392. One shot shows the wing root fairing where Bill has put a slight break along the edge to close up the gap you are talking about

Bill, I think the "proper clamps" Mike mentioned are shown as 80002-27 "CLAMP - Cowl support tube" in the PA-18 parts catalog. Univair has them. I tried using adel clamps, with and without the rubber sleeve, but was unsuccessful in keeping them where I wanted them. The Univair part stays put.