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Building a Javron Cub

Pete,

I wish you had told me that 4 years ago. I had to get fancy with custom made needles to do single stitches in that area. Character building it was.

Colin
 
Bill,

I, too, believe mounting and rigging the wings and flight controls prior to cover is very important.

If you completely mount and correctly rig the wings, tail, control surfaces, fuel tanks and plumbing prior to covering, not only will you to be able to identify and correct any problems, the final assembly will be so much easier because the wash out, turnbuckles, feel wires etc. have already been set.

Didnt you do that on your first build?

Paul
 
Wing Rib Stitch

I am well into stitching the first wing and I will offer this opinion. Due to the rib shape, and wing trailing edge reinforcement etc, I think, on this particular wing, you might want to consider riveting the fabric on. If you plan to stitch it (still my preference) you will have to drill some holes for the stitches and as a result you will want to plan all your stitches BEFORE you cover. It can be done after the fact, as I am discovering, but it takes quite a lot longer and it goes slower. I am still happy and I like the way it coming out but this is just a suggestion for others who may build up a Javron wing/kit to save time.

Bill

FWIW you may be interested to know that Cub Crafters switched to fabric rivets this year. Although one could either stitch or rivet the EX, I plan to go with the rivets. Factory planes are riveted.

Chuck
 
Pete - excellent suggestion to cover one side, stitch then cover the other side. Never thought of that. Thanks

Denny, Paul and Mike - Thank you for that excellent input as well. Yes, better to rig, and actually to build entire airplane, before cover. Saves time in the long run. I agree with your idea. I did not do it, (on either build), but that is my issue and does not necessarily reflect best practices.

Wing Stitching (Lacing for wordsmiths)

First off let me emphasize that this has nothing to do with structural integrity, wing strength, flight characteristics, etc. It is all about aesthetics. How to make this cover job look pretty. I am a little anal retentive ( or is it hyphenated?.... anal-retentive) (thats a joke folks) and I like everything to be even, symmetrical, lined up, consistent and all that. So with this wing we have a couple of hurdles, remember a saying I gave you earlier......
Building an Airplane - Its Just a Series of Problems to be Solved

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Jays ribs have a little doubler where the nose rib is attached to the main rib and where the tail rib is attached. 3 piece rib riveted together.
I have asked Jay to look into changing this doubler to make rib stitching easier and he is doing that now. So future Javron wing ribs may not have this issue, depending on when you get your wings, (or ribs if building your own wings). Remember, I got the first set of wings and there will likely be improvements as time goes on.

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Nose rib doubler

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Tail doubler

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Nose rib doublers showing through under the fabric

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Tail doublers showing under the fabric

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Another problem area. This is the rear spar beaf up that allows us to go to 2200 pound gross weight, (or you can set it where ever you want - 2300, 2100, 2400, but the engineering was based on 2200 if I remember correctly). This area can only be either glued, as Skywagon8A Pete notes, or drilled and stitched, or riveted. I personally do not care for rivets. I think they stick up and look unattractive under the tapes, and recover jobs are a real pain, and I don't think they save all that much time by the time you drill all those holes and then debur them. My opinion only. One of the reasons factories do it is their ribs can be made with the holes drilled during manufacture, so for them it can save man hours, and they don't have to worry about recovering. This is another area Jay is going to look into. To see if the rear spar can be satisfactorily reinforced in a different manner so that he does not have this large box in this area. So future wings may not have these same cosmetic conundrums. I don't have any idea what the time line on this might be. I would expect the first 10 or 20 sets of wings will go out like mine, they are certainly good wings, before he has the chance to make changes. Don't know.

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This a stitch into a doubler that has been drilled. Fits nicely under the tape.

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This is a stitch over the width of the doubler. It barely fits under the tape and in fact, is not entirely covered by the tape. You could put the tape a little off center of the rib to ensure all holes are covered but then that looks funny. Or you could add a little bubble tape here. That would look funny to me too. Or you could tape all the ribs with 3" tapes. OK, that could work. The stitches up at the front, the first stitch if you will (behind the main spar) can and will be covered by the transverse tape that runs along the main spar. A 3" tape here will not look funny and will cover these stitch holes. So....1 problem out of three solved.
We can also use a 2" transverse tape along the rear spar and it would probably not look too funny and it would solve the rear doubler issue. # 2 solved. Or a wider rib tape, or pre drill the doublers, etc. Several options, especially now that you know in advance, about this issue. Then we just have to take Pete's suggestion to glue the fabric down to that rear spar box and we are done. Or you could pre-drill, or rivet. #3 solved.

Hope this helps

Bill
 
That clarifies things quite a bit. To stitch, as I understand it, one would have to space (plan, as you stated) his stitching and drill holes to accept the needle and try to stay perpendicular (or radial?) to the top rip. Apparently, I think, when you are stitching along a section of "normal" rib you're just stitching normally with the needle along the sides of the ribs.

Thank you for the time and effort you took to give photo's and commentary sufficient to thoroughly describe.
 
Bill, I am the one blessed. This Cub has been my lifelong aviation dream. Thank you and all the genuine friends I met at "The Gathering". We are really looking forward to Johnson Creek among other fly ins. Now I'm on a vertical learning curve!
 
Before you do your first coat of silver, iron your rib stitches down flat. You can make them almost disappear.
 
Bill,
Judging by the pictures of the nose and tail rib doublers, it appears that the flange could be bent in the opposite direction and be hidden under the rib cap strip. The load path would be the same.
 
Thanks for the inputs. Lots of good ideas.

Stitching is going well now that I have a plan.

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Buck came over and walked his BD5 home. Like pushing a shopping cart. :)

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Jim, a friend and neighbor that was a big help on my last build, recently purchased a Legend Cub. That is a pretty cool Cub!!
He let me take it for a spin (figuratively speaking) and I was quite impressed by the handling, smoothness of the engine/prop combo, and certainly by the fit and finish. This is a nice airplane. Like everything Jim owns it is absolutely immaculate. Very Very nice.

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Jim managed to scarf up a set of the Baumann 1500 Amphib floats last year so he is going to have a sweet combo when he marries them up.

Bill
 
The Legends are nice birds... I could never figure out what the airframe is cloning. looks like a J3, but the top is not like a J3 and it's a bit wider?... tail is PA-11/J3 like but not exactly from a quick measurement in FL last year. So what is Legend based on? Never really seen a PA-11... :???:
 
Folks

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One wing stitched and all rib tapes on and a couple of others. Still another day or two taping then this wing will be ready for primer. I managed to get in about 30 hours in the last four days. Now its back to my real job for a couple of days. I do think the Stewarts glue system on this part would be much faster than Airtec glue but I'm very pleased with the way it is coming out,......... I'm just sloooooow.



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It really helps to put it in the wing rotator. I got this 7 years ago from Wag-Aero. Don't know if they still make them but it sure is handy.



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Another view of the rotator. WARNING - this thing will "walk" as you rotate it and it will fall over. I screwed the wing root part to the floor. Problem solved.
I learned this the hard way on my last build.

Hope this helps

Bill
 
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Yeah, they'll walk. I've bought a used Bogert fuselage/wing rotator 18 years ago. My fuselage is now mounted upon it. The mounts walk because, as you know, the wing attachments are not perpendicular and level with each other. The stands will flex, twist, and effectively walk.

I always remember what a fellow told me years ago about things like this. He said "That's just their nature, that's how they they behave". There's something "calming" about the way he put it.

That's their nature.
 
Wing Reinforcements and Tapes

After the two big pieces of fabric are on you will end up with a bit of a mess around the flap and aileron hangars like this.......

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And this......



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So I put a reinforcement around this area. I used regular fabric rather than tapes. What I am trying to achieve is a tight bond of fabric to the hanger with a small fillet.



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The hanger measures 24/32 x 20/32. So I made the middle square a little smaller than the hanger. I made it 20/32 x 16/32. That way it fits tight against the hanger and creates a small fillet. I used 1" around the outside. Draw up a set for the other wing while you are at it. A little glue on the lines will keep the fabric from fraying when you cut it out.

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This is what it looks like when you glue it on.



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View of the cove with the hanger reinforcements and also the edge tapes in place.

I'm sure there are other ways (and probably better ones at that) but at least you have one idea now.

Hope it helps

Bill
 
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Bolt electrical channel from Menard's between the legs and it will be rock solid. You will be able to put it on two dollies and move it into your paint booth.

Ray
 

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Ray - Great idea. Thanks.

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This is a tricky area. It is not really obvious, unless you look closely at a completed Cub, but the wing strut extends slightly inside the fabric line, thus you have to make a little pocket for the top of the strut to fit into. I lay a strip in like this.

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Then I cut my reinforcement like this. That way when the two center parts don't meet up in the pocket there is a bed for them to lay on, thus reinforcing and further establishing the pocket.


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You can see the pocket here.


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Be sure to close up all the gaps and get it sealed up. (I need to get rid of the pinked edges on the far brace. Looks bad.)



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The bottom of the coffee pot is just the right size for the inspection ring doilies. Sometimes you have to get creative.......

Hope this helps

Bill
 
What the Heck!? Well, here's another darn thing I'm gonna' have to figure out to make my Cub be up-to-speed with the Jones'.

Bill, you're gonna' have to quit this... You're showin' us up. Now, I'm going to have to go back down to the airport to see how my Legend's strut attachments are covered. I may just get two of those plastic Cessna strut fairings and use them.
 
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Fixed the pinked edge on the strut attach bracket that I did not like in the post above.


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You can see where I put access panels and reinforcements. Note - your wing may be different, round tip may not be the same. Basically a round inspection cover for all the drag-anti-drag wires, a square one for the aileron pulley, and a square one for the flap bellcrank.


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A thought in hindsight. This bay would be perfect for a few nutplates and a screwed on access panel. Use the rib flanges, trailing edge cove, and rivet in an angle at the front just over the spar and you have a perfect box for a panel. Much larger than the standard fabric panel I am holding. I think it would be worth your time to do this.


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One down and in the rack. Covered and ready for primer it weighed 78.9 pounds. Before fabric it weighed 73.85. So.....all fabric, tapes, reinforcements, glue, etc weighed 5.05 pounds


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Next one started.

Hope this helps


Bill
 
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For as detail oriented as Bill is, I'm surprised how much he gets done. Hope not assembling the airframe before covering, doesn't come back to bite. After rib stitching several wings, I just love punching holes in those flanged ribs and installing aluminum rivets. Plus I'm not worried about those edges cutting my stitching.

I'm sure he has it all figured out.
 
Bill Rusk; said:
....... and a square one for the flap bellcrank.


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A thought in hindsight. This bay would be perfect for a few nutplates and a screwed on access panel. Use the rib flanges, trailing edge cove, and rivet in an angle at the front just over the spar and you have a perfect box for a panel. Much larger than the standard fabric panel I am holding. I think it would be worth your time to do this.

Bill

Bill, I know that it is too late to help you, but perhaps this will give some others an idea? In this area I used the ribs for the ends of the opening. Connected them with two angles. Installed a piano hinge on the forward angle over the spar and two cam-lock receptacles on the rear angle. Then I made a door which easily opens the entire bellcrank space for access. Turnbuckle adjusting/safetying etc. Glad that I did this over each of the four flap bellcranks on my wings. Now it is relatively easy to get both hands in there.
 
That is an even better idea, Pete. I like that. Great idea, wish I had done it, but...... live and learn, but again, that is part of the reason for this thread, so other people can learn too and get ideas.

Thank you.

Bill
 
Sky,

That idea sure would save a lot of nut plates to install the panel I was planning to use at those locations. I'm stuck on RV mentality some times...especially with an alum skinned wing. I think we should keep you around!!!
 
Sky,

That idea sure would save a lot of nut plates to install the panel I was planning to use at those locations. I'm stuck on RV mentality some times...especially with an alum skinned wing. I think we should keep you around!!!
Low,
Your wing, I believe, has a stressed skin structure. You should not arbitrarily cut holes without proper reinforcement. Pay attention to the structural load paths. If the original design had a rectangular hole in this location, you still need to pay attention since the screwed on door/plate may be structural. Bill's is just fabric, no structure. Ask the question, "Is the structure safe/sound without the inspection plate installed?".
 
Sky,

I don't mean to steal Bill's thread, but the idea I had was to rivet a backing plate in the 0.020 skin made from 0.025 that the cover would seat against and support the skin around the opening. I'd change that by using your hinged cover and cam locks instead of the screws and nut plates. I understand what you are saying about the cover missing but thought the backing plate and angle would make up for that...maybe 3 cam locks on the back of a 6" access cover.

Bill,

As usual, I'm inspired by your workmenship!!
 
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Had a long PDX overnight so got together with DW and had a chance to fly his Cub with the new Keller Flaps. WOW!!! AWESOME!!! I had flown the flaps on the Keller test airplane (very stock SC) and they were a definite improvement but DW's Cub has larger flaps thus the replacement Keller flaps are larger and the difference in performance was just HUGE. Shorter TO runs, much lower deck angle on approach. DW also has a electro/hydraulic flap release mechanism that with the push of a button/trigger on the stick retracts (or dumps) the flaps and again that is a big plus for really short field stuff. DW's Cub is a very high end bush Cub and it performs much better than more stock Cubs. Valdez winner for sure if he would compete more often.

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So we flew down on the river a bit but it was a Saturday and a perfect weather day, thus all the sand bars we wanted to play on were occupied by campers, fishermen, canoes, tents, ATV's and all manner of NOT sparsely populated.

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This is the latest project Cub at the Keller Skunkworks shop. It has lots of neat innovation and cool stuff.

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We did manage to find some rather tall grass to play in.

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You know it is high when it is taller than 35" Bushwheels.

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Glad I don't have to clean up that mess. It is amazing how much fun you can have in a Cub.

Thanks DW. Great time.

Bill
 
You guys have way too much fun! How is the Catto handeling the tall grass???

I like the idea of the flap retract mechanism. Will maybe try to fit one simple electric on my flap handle.
 
Had a long PDX overnight so got together with DW and had a chance to fly his Cub with the new Keller Flaps. WOW!!! AWESOME!!! I had flown the flaps on the Keller test airplane (very stock SC) and they were a definite improvement but DW's Cub has larger flaps thus the replacement Keller flaps are larger and the difference in performance was just HUGE. Shorter TO runs, much lower deck angle on approach. DW also has a electro/hydraulic flap release mechanism that with the push of a button/trigger on the stick retracts (or dumps) the flaps and again that is a big plus for really short field stuff.
Bill
So do you think that you'll make any changes in the flaps on this build?
 
Fair question. I am very very impressed with the Keller flaps, but at this point I am going to focus on getting this bird done. The Keller flaps are an easy mod after the fact, so the plan is to get her done then look into more improvements.
Because of the squared wing the flaps on my Cub will be larger. A standard round tip Cub wing has a 102" aileron and a 62"flap. On the Javron square tip wing the aileron is the same length as a round tip wing, 102", but it is shifted out to the wingtip, the flap then is built larger to make up the difference, thus the flap is 88". So the flap on a square tip Javron wing grows from 62" to 88".

One of the things that happens in a build is that great mods are discovered as you go but, at some point, you have to stop all the side roads and finalize the configuration. Delay avionics and engine as long as possible, as those are areas where advancements and improvements are being made daily.

My opinion only

Bill
 
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