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Yes, another Javron cub

stoldriver

Registered User
Arizona
Well, I just took possession of my Javron Super Cub kit and of course, one of the things you have to do is start a build thread. �� Lead time was 18 months, considerably longer than expected, but there you go. Kit quality is superb and pretty much everybody I've shown it to agrees. I'm still short a few parts but I have no doubt I will get them. The wing is a work of art. I've had it about a week now and thought I would try to document some of it here. Not going to try to compete with Bills thread but thought maybe there were some things that could be added. Mostly, I'm thinking it would be a good idea to have a few sc.org folks looking over my shoulder to let me know when I goof up. I may not be good, but I'm slow. �� First thing I've learned, while the old backcountry manual is a great resource, things have changed since then. Example, I'm looking for 6 stringers, and only find 4. Turns out I'm not short, instead, Jay now welds the upper side stringers into the frame. Anyway, just an example. Like I said, the old build manual l is great, but you can't just use it blindly, you have to figure out what's right and whats superseded. I've still got to figure out how to post photos but I'll put some up.

Wayne
 
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Nice! Picked up my wings about 6 weeks ago - agree, so nice. Looking forward to seeing your progress.
 
I see something right off the bat for your consideration. There is a screw on fairing which goes over the wing trailing edge fabric, which closes the gap between the wing and the flaps when they are up. Instead of the screw on fairing, glue on a piece of balsa wood cut and sanded to shape, then cover the wood with a fabric tape. Use the covered flap as a sanding block to shape the balsa. Allow just enough clearance for the finish tape when sanding. This makes a nice well shaped fairing which does an excellent job of smoothing the airflow over the flaps which is critical for airflow over the tail and improving lift from the flaps. I also used a strip of tephlon tape under the trailing edge as chafe protection between the flap and wing.

That S2F will need to move to make room for the Cub. :p
 
I always enjoy following these build threads. Interesting to see the innovation used to build a Super Cub.

I will never understand why a kit manufacturer would not have a build manual. I would think it would be imperative to more flying airplanes. This website has been very helpful for many, many Javron builders but I see no support from Javron financially nor technically.
 
Frankly, sw8a, I'm amazed you could get so much detail from a not very good photo. Kidding, but I'll try to figure out what you mean. The S2 is one sold to Japan. It's been sitting across the airport for 30 or 40 years but one of the radials is still leaking oil. Go figure.

Steve, I'm a little conflicted about the whole Javron no manual thing. It would be nice to have a manual to help avoid some don't dos, but I also think much of the creative building is a direct result of not having one. I don't have a manual so I have to figure out how to do it, kind of thing. Does result in some mistakes, I'm sure.

On to things learned this week. Don't mark wood floor boards with ink. I forgot this when I started and marked a tiny dot where I was going to drill a hole. On the second measurement, (we all measure twice, cut once, right?) I found it was about a half inch off. It won't sand out, so now I have a tiny black dot on one floor board. Luckily, I started with the aft baggage so it won't be in a visible place.

A couple of people have mentioned how great these rivet fans are.
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You can also use them to transfer dimensions, like to keep left hand floor board hole spacing consistent with right hand. A word of warning, if you fully extend one, they can be a bear to collapse them back down. I spent a half hour doing that. More to come.

Wayne
 

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I stained my floorboards with a dark brown stain before a clear urethane top coat. That should cover your ink spot.
 
Here are some pictures to go with my above comments.

Flaps up. 20230610_124324.jpg . 20230610_124801.jpg

The small triangle is the wing's original trailing edge. The larger setback triangle is the added balsa wood. The white is the Tephlon tape.

Flaps down. The gap is a strong 3'8". 20230610_124513.jpg . 20230610_124550.jpg
 

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I ordered a Javron kit last week. I want it next October,,, not two Octobers from now,, Oshkosh 2024 is my goal.. Hope Javron will get them out sooner than 18 months…
 
OK, that wasn't what I thought you were talking about. I was thinking wing root but I think you are talking about essentially a flap gap seal, right? Why do you have the little section of original trailing edge? Making room for the ailerons, maybe?

Wayne
 
No, I just stopped the balsa at the end of the flap. If I ran it to the end, the balsa would not have had any protection from the flap so could possibly have been susceptible to damage. Just a personal choice. Some call it a fairing and some call it a flap gap seal....same thing.

I taped some yarn to the trailing edge of the flap. With full flaps in a stall, the yarn flowed smoothly straight back indicating smooth airflow and no stalling of the flap in the section outboard of the propwash. Also there has never been any "Cub tail shake" at any power setting.
 
With everybody wanting their cub different, the piper drawings widely available, thousands of pictures and threads on this site and others, I see no reason for a build manual. Most of it is common sense, and the unique stuff is just a quick phone call away. Other "build manuals" for other non cub kits mostly all suck and dont go into enough detail or are so poorly described that your better off tossing the manual out and going at it like orville and wilbur.
 
A basic build manual like Bill Rusk Javron wing build is a great help. It is the small stuff like notch this rib or adjust for this that really helps. I would agree Supercub.Org is the bust build manual ever!!!
DENNY
 
With everybody wanting their cub different, the piper drawings widely available, thousands of pictures and threads on this site and others, I see no reason for a build manual. Most of it is common sense, and the unique stuff is just a quick phone call away. Other "build manuals" for other non cub kits mostly all suck and dont go into enough detail or are so poorly described that your better off tossing the manual out and going at it like orville and wilbur.
How hard is it to get Jay on the phone to ask that unique stuff, quick question?
 
How hard is it to get Jay on the phone to ask that unique stuff, quick question?

I can answer that question, Jay has been (so far) very easy to get a hold of, and has always had a good answer for my build questions. having already built a Smith cub, I have a pretty good understanding of the process. His production times, from what I understand, are getting better, he has had trouble retaining employees, (so is my company) Materials have been slow to come with supply chain issues still prevalent, (same here in my business ) I ordered my kit August 2021 and picked it up January 2023, I am a very patient person and the wait was well worth it, the product of Jays workmanship is amazing. you can always tell a machinists work, it is perfection.

Rick
 
Hadn't really intended this thread to be a review of Javron, but there seems to be some discussion of it, so here's my very brief thoughts. The Javron kit, in my opinion, remains, if not the best, at least one of the best values on the market. If you are buying it for that reason, then you are golden. If you are buying it solely due to the lead time quoted, well, I suspect you'll be disappointed. The quality of the Javron parts are widely recognized as very good. Enough of that.

Stringers. I notched mine where they came into channels. Bill has a good description in his thread. It appears to me that the piper drawings show a similar thing. Some show a slope in the end of the stringer. Wherever I needed to bend, I annealed the area where I wanted the bend to occur. A tip from Jay is to apply marker ink to the stringer and then heat until the ink has mostly disappeared. This seems to work very well and is what I did. I used a torch and it doesn't take long. The aluminum is very soft where annealed so go lightly when bending. If you want a particular bend radius, find something of that diameter and use it to bend the stringer over. Be careful of the stringer tipping over on you and twisting. Stingers are not structural and there should be no issue with sections of it being annealed, especially since those areas usually have a tube under them or are where the fabric comes off. I attached the stringers with provided tabs using small #6 screws with self locking nuts. For the side stringers, I followed what piper shows in the drawing and wrapped the tube in tape, drilled a small hole in the stringer web, and safety wired in place. 20230612_144214.jpgFirst attempt was pretty wavy looking so I tied a guide string front to back and that helped.

Control cables are complete in the kit, but unless you are a masochist, the first thing you want to do is tape the ends.
20230612_144259.jpgYou are not trying to seal it, which would be a questionable thing in my opinion. You are just trying to cover those pesky little wires so they aren't continually making little holes in your skin. Rudder cables are identical so doesn't matter which is where. Run them up the side through the little rings which will have fairleads in them.
20230612_144343.jpgYou have to run from back to front since the rear cable terminal won't fit through the fairlead rings. The front end is the end with the short cable section which attach to the rudder pedals. More later.

Wayne
 

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Oillite bushing installation. Not that complicated and people have been tapping them in for decades. That does tiny amounts of damage as you tap them in due to the slight interference fit. Probably means nothing but there is a way to minimize that. Where I used to work, we always used temperature differential for press fits. All materials expand or contract with changes in temperature. So if you heat the outside one up and maybe cool down the inside one, magic, and you have no press fit. Drop the inside one in and wait until they return to uniform temps and you're done. In this case, I heated up the airframe piece and did not bother chilling the bushing. This is not a job for a torch. You want some level of control on how much heat you apply. I used my Steinel heat gun set at 250F. That temp is way down on the steel temper range and will effect nothing negatively. In some cases, the bushing dropped in and in others I had to help it a little with my Knipex smooth jaws and appropriate pads. Don't forget to use some gloves since those airframe rings will be hot.

It's getting hot here. A touch over 100 today. I may have to turn on the fan in the hangar pretty soon. :???:

Wayne
 
This post will start documenting differences to the Backcountry manual. Everything here is my opinion only. The manual starts with the stab trim yoke. You don't have to start there but you can if you have all the parts. The yoke install is pretty similar with some differences. The grease zerk is not a -6 so don't pre-order one. It won't fit. :???: I'll post here when I figure out what size it is. Washers on the jack screw are a little different but not that much. The key here is to make sure the jack screw only touches fuselage on the two diameters. End faces of the jack screw should touch a washer. This is mostly for wear purposes. If you have to replace a part due to wear, you don't want it to be the fuselage. By the way, the jack screw pipe comes with the inner stab tube installed. The inner tube is a thing of beauty with a high finish so I would recommend either removing it and storing somewhere safe or tape it up to protect it and keep it from falling out. Speaking of the key, the key is included and is pretty much to size. All I did was run it across a file flat-wise to make it a tiny bit thinner so it so it would fit in the slot. The radius on the key goes in the radius of the milled slot of the jack screw. A little grease helps it stay in place. I did not measure where the manual says to nor did I file it to length. Putting the pulley on the jack screw is a pretty fiddly job but you'll eventually get it. You have to keep the key in place, make sure the cable is on the pulley, and put washers and nuts on. I did it several times. The kit comes with the hardware in a divided box, very nice, and is labeled like this.
20230623_143947.jpg
If you were doing this job, you might look for bin 8 for the appropriate hardware. I think. I'll go into cable routing next post

Wayne
 

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My goal for cable routing was to make sure they didn't rub on one another (or anything else, for that matter) and that they would have the correct relative direction between the front crank and rear jack screw. I couldn't make out in the photos or drawings which way the cables ran on the pulleys so I basically just did it multiple ways until I came up with an installation I thought was OK. Here's what I ended up with.20230623_144342.jpg
In the photo of the aft jack screw pulley, you can see the port side cable coming on to the port side of the upper groove. Also notice the little posts on the outside of the pulley. It's real easy when putting the pulley on the jack screw to have the cable slip outside of that post. I had that happen more times than I want to admit. The cable is supposed to be inside those posts. The cable comes off the starboard side of the upper groove and goes forward to the tensioning pulley, starboard side. Around the pulley and back to the port side of the lower groove, around the double pulley and forward. This appears to be how the manual shows it. Going forward, it's different from the Backcountry manual but has similarities to the Piper drawings.. I'll describe what i did for the side trim. There is an option for overhead trim which would differ from this. For side, the cables go forward to a couple of small pulleys.
20230623_131859.jpg
From there, forward to two more small pulleys. From there, forward through a couple of fairleads made of plastic. Piper calls them cable guide blocks. See the fuselage assembly drawing for the Piper version. Here, one is on a vertical tube and one on a canted tube.
20230623_131826.jpg
One also has a hole in it which will be for the trim indicator cable. You will have to thread the indicator cable through that hole before you swage the end. You'll bend the tabs over the plastic to keep it in place. From there, forward to the forward double pulley. I made sure the cables didn't cross coming forward.
20230630_144807.jpgUpper cable I have coming forward to the outboard groove of the cranked double pulley then down to the forward side of the idler pulley, back up to the inboard groove of the double pulley, and the back to the tail. This appears to be exactly like the Piper drawing. As I get more in to this kit, I find myself using the Piper drawings more and more. Many of the parts received appear to be exact copies of Piper. So far, I have only installed two cotter keys nor torqued any nuts. This gives me the opportunity to disassemble stuff which I do fairly often. The assembly and installation drawings are a huge help. Many, many thanks to Christian for his great website and the access to the drawings.

Wayne
 

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Is it still common practice to install a washer under the jackscrew on top of the fuselage bushing? A lot of the cubs I've seen getting put together lately including javron kits people are just tossing jackscrew in. Parts manual is lackluster.
 
Use this with the illustrated parts catalog. I use Christians drawings, Northland drawings, Short Wing Piper drawings and the Vagabond drawings for all those small parts like washers, bushings etc.
This is an exert from an article I wrote years ago for Cub publication:

The main components of the stabilizer adjustment system are the yoke and jackscrew. The stabilizer yoke has a flat side and a “V” shaped side. The “V” should point down on any Piper with the trim on the side wall. When installing the stabilizer yoke and jackscrew in a Super Cub it is best to use Figure 48 in the PA18 Parts Manual as a guide. The problem with the parts manual is that the part numbers get confusing. Hopefully I can clear some of this up by relaying a little information I have gathered by researching lots of Piper drawings. The parts are as follows starting with the index number depicted on Figure 48:


11 part# 42961-02 Stabilizer Adjustment Screw
12 part# 11008-00 Stabilizer Adjustment Pulley
13 part# 80122-41 Washer measuring 1” O.D. x .375/.385” I.D. x .095” thick
14 part# 81342-05 Washer measuring 1 1/8” O.D. x .375/.385” I.D. x .062” thick
15 part# 85012-12 Washer measures the same as an AN960-616L
16 part# 80122-24 Washer measuring 3/4” O.D. x .328” I.D. x .062” thick
17 part#81342-08 Washer measuring 5/8” O.D. x .313/.323” I.D. x .032” thick
Not listed are the two AN5-7A bolts and AN365-528 nuts that hold the stabilizer yoke to the liner tube link assembly index #9 part# 14180-02. There is also an AN280-304 (#2Woodruff key) that is trimmed to .320/.334” long that retains the 11008-00 pulley to the 42961-02 adjustment screw.

With the above information and Figure 48 in most early PA18 parts manuals the assembly should be pretty straight forward.
 
I'm trying to line up an engine now and my advice would be if you have ordered a kit, order your engine. Don't wait until you have your kit like I did. For right now, July of 23, the shortest lead time I've had so far is 6 to 8 months and I've seen a lot of optimism in lead time quotes lately. Superior won't even quote. They say they are waiting for cranks and don't expect any for 18 to 24 months. They told me the same thing 6 months ago so not sure what that means. I've asked for quotes on an o-360 or clone, conical mounts, carb'd, dual p-mags, mogas capable. Except for the p-mags, a pretty ordinary motor. Every quote I've received so far is well north of $40k with some pushing very close or over 50. I'll wind up buying one, I suppose. Don't have much choice, but that's about 100% inflation in just a couple years and feels like I'm being taken advantage of.

Wayne
 
More lessons learned. First, I was wrong earlier about control cables being complete. The trim indicator cable is not terminated on either end and the flap cables are not terminated in the wing (one end). Also, don't be in a hurry to terminate the trim indicator cable. If you follow the Piper drawings, the indicator is shown centered on the trim side plate. I fiddled with it, looking only at the spring tension and terminated it at what I thought looked good. Now that I've gone farther, I recognize that I have it terminated such that the center of trim is about an inch left of the center of the trim panel. So now I need to find a source for a new swage ferrule to adjust it. Also, no matter how cool it looks and makes you feel like you are making progress, don't leave the newly assembled baggage doors in place on the fuselage unless you actually have them physically attached to the fuselage frame. If you do, at some point, you will bump the bottom of the door and it will pop out and plummet to the floor. I can now tell you that they won't do that without incurring some sort of damage.:cry:

Wayne
 
Go to a store that has a good selection of fishing equipment. Get some ferrules used to make leaders.
 
The forward end of the trim system does not use the trim panel or indicator as described in the BC manual. It is essentially per the Piper drawings. All parts look just like the Piper drawings including the trim indicator and all the parts in the crank handle stack up.

Elevator balance cable install, fin install, bushing install are all well represented by the manual and/or the drawings. Stringer install is similar with a few differences. Upper and lower stringers are pretty much the same. The upper side stringers are welded in on newer kits so you don't have to do those. Side stringers about the same except its not very detailed in the manual so look at the drawings too. I did not tie the aft ends of the side stringers together as shown in the manual, just bent them in to make sure the fabric doesn't come off the end of the stringer. The radius fin fairing is shown in the manual getting a rivet to the upper stringer. The Piper drawing does not show that rivet and I chose to do it per the drawing. The rivet would definitely show thru the fabric, I think. I did file the ends of the radius fairing to a little sharper edge to reduce the step.

Floorboards, you get 6 instead of the 5 shown in the manual. Javron added the seat back for the back seat. For the baggage floor, you need to make clearance for some fuselage tubes. You can mess the plywood up depending upon how you choose to do that so be careful. As many do, I chose to use nutplates rather than use the provided nuts. Manual gives some good tips on installing the boards. The number 2 floor plate caused me some angst. It is supported at the front adjacent to the front board and at the back by some fuse tubes but the fuselage takes a non-straight path in between which means the center of the board is about an inch above the tube in the middle. Then you just push that board down and pull it into place with the screws. Some people put a spacer block in there but Piper didn't so I didn't.

Wayne
 
Seat base goes in just like the manual. I found it easier to slide it sideways into position rather than just jam it straight down. One thing to be aware of is that there are two versions of the seat base. They look like this.
20230618_121627_1.jpg20230731_100610.jpg
Note that one has an additional tab on one of the legs. That tab with the hole in it is used to support the standard flap handle. If you have the overhead flaps, you should have the one without the tab. Given the similarity, there is a potential that you could get the wrong one. I did. Check before you go to the work of installing it to make sure you have the correct version and if you have the wrong one, just call Jay and he'll make it right.

Rudder pedals installation is accurate if not detailed in the manual. I used the Piper drawings to augment any lacks in the manual. I know a lot of people remove powder coat from the pedals for each saddle fitting but I only did if it was binding at all. That came out to be two of them. Other than those, there was no binding and I figured the more corrosion protection, the better. The saddles come with cad plate and no powder coat.
20230530_140127_1.jpg
They are under the floor, out of sight but you may choose to powder coat them too, like the pedals are. That may change how much clean up you have to do. I primed and painted mine for corrosion protection but removed the paint from the inside contact surface. Mine were put together with the nuts provided in the kit. I may go back and put nut plates in but haven't yet. The pedal return springs are pretty strong so don't get your finger where it will get snapped by the spring. Lubriplate is your friend here but too much will make a mess.

The brake reinforcement plate does not match the oval holes on the floorboard. You can kind of see it in this photo.
20230804_111635.jpg
I measured and it appears that the floorboard is not exactly per the print but the plate seems to be. If you are making some floorboards and plan on using the provided ones for pattern, keep that in mind. I may or may not do something about that. It's not really visible unless you really look close.

Wayne
 

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I'm still trying to figure out the value of nutplates on all the under floor saddles. Maybe somebody can help me. I get that it is nice to be able to remove all the fasteners without access from the belly. You can for sure get the floor out easier. The issue I can't figure out, is how do you put the floor back in. All the saddles are off and it seems you now have to have access from the belly to reassemble. Am I missing something? :sad: I saw a photo on here, from Steve maybe, that showed the saddles all wired in place which seemed like a good idea. Good for putting the floor back in but it seems to me you kind of need to remove the pedals to get the floor out and if the saddles are wired in, that seems like it would be difficult to do. Help me out here. Seems like I'm missing something or I'm just wrong about something. Thanks.

Wayne
 
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