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Building a Javron Cub

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Part of the machine shop that is Javron. Jay DeRosier, owner and maker of my kit. The Javron Cub.

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Jay taking another order. Note the airplane prints on the wall. This guy is an airplane nut.

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The fabrication area in Jays shop. Note the railroad size I beams in the lower right part of the picture. This is the start of a new jig. Jay says they give a stable platform for the jig base. Yea, no kidding.

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Jays PA-12 project. I doubt he has much time to work on it.

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This is how my parts were packed. I was very pleased. Everything was carefully packed and ready for pick up. I brought all kinds of rags, bed sheets, towels, etc for packing but needed very little as Jay had everything ready to go. That was REALLY nice. Attention to detail.

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After carefully going over the fuselage, Jay (shown here) and I wrapped it in plastic and shrink wrap for the trip home. I was prepared to put it on the truck bare but Jay insisted we wrap it. He says "no way you are going to mess up my fuselage your way home".

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Jays lovely wife, Cathy, stopped by for a visit while we were wrapping the fuselage. Neat lady. Jay is a Blessed man.


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Brad Thornberg, Cubus Maximus, also came by. Brad is a very talented photographer. Go to his album under Cubus Maximus, to see his work. It was really nice to get to visit with him as well on this trip. These photos are mine not his. His would be MUCH better.


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Me, wrapping the fuselage.

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The rest of are working and here is Jay laying down on the job.

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Wrapped and ready to go. Note the look of fear on Jays face. I was heading into a snowstorm to get home.

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I ain't skeeered.

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The obligatory handshake photo. Actually, the smiles are from me telling Jay I'll buy another fuselage if I wreck this one on the way home. The trip home was not too bad but semi trucks did really blow me around. I need a bigger, read that heavier, pick-up truck.

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And we're off. A happy camper heading home.

Bill
 
Hey, Bill, thanks for posting the photos. What a nice endorsement for Javron. It is great to feel your energy as it has returned, Bill. We are blessed to have you around.

Randy
 
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Home with the fuselage. My fuselage, bare (not on gear as shown) weighed 100.23 pounds prior to powder coating. I used a two step powder coating. First coat was a zinc rich primer. Second coat was paint. Finished weight was 104.95 on Jays scale and 104.50 on my scale. I was pleased that our scales were that close together. So, about 4.5 pounds for primer and paint. Perhaps a non powdercoat job would be lighter but until someone primes and paints (not just primer) and weighs it accurately we do not know. I am very pleased with both the final weight and finish on my fuselage. With all the mods I added I feel we came in very light. The primer step was added at my request and cost. This is not normally done by any other kit manufacturer to my knowledge. Normally they just clean with a phosphoric wash and topcoat. No primer.

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Jay packages the parts nicely.

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Hardware nicely packaged and labeled.

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This is the firewall X brace. I put blue tape on the added tube so you would be able to tell what I am referring to. This tube helps keep the firewall from crushing upwards in a mishap. This mod adds 15.3 oz total for both sides. It's worth it. (disregard the upside down engine mount)

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The two tubes do not normally touch so I had Jay weld them together for added strength and rigidity.

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Bungee landing gear. The die spring gear weighs 167.22oz, the bungee set up weighs 127.605oz. Saving 39.615oz or 2.45 pounds. Yes, I will have to replace bungees and incur more time and cost over die springs. It is not as good as AOSS but it is MUCH lighter. You will have to decide what works for you. This works for me.

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The Atlee long step, with all mounting hardware, weighs 45.32oz. The Javron long step, with all mounting hardware, weighs 21.010oz.

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Jay bushed the gear leg at my request for the long step. I honestly do not know what all Jay does as standard on his kits. I just went in to him with a list of all the things I wanted and he did it and came up with a total price. I am offering this so folks will not assume that this stuff is standard and then get upset with Javron when they don't get it. Some of the stuff I will present here is standard on his kits and some is not. If you purchase Javron parts or a kit you will need to work that out with Jay.





I am going to try to post all the mods I did and the weights and reasons for each. It takes a lot of time to do this so it may take me a while. Thanks for your patience.

Hope this helps.

Bill
 
This is part of the letter I sent to Jay to get the kit started. It includes most but perhaps not all of the mods on the fuselage. I will try to list out the other stuff we talked about and did verbally to give you a more complete listing of mods. Again some of this stuff is standard (like the reverse dogleg) and some is not. I am not telling you to do this or not. This is just what I did to give folks some ideas and to share the knowledge I have gained from all the awesome folks on this website.


Fuselage

* Narrow body
* Single door, clamshell type, on right side
* Standard “D” windows
* Extended Baggage to rest on lower longerons, thus elevator cables to run below
fuselage
* Dual tail lift handles (slightly heavier than factory and slightly deeper)
* Lower right side baggage door
* Upper right side baggage door
* No trim system components, tabs, guides, or welded on items for any trim related
parts (I will be doing an electric trim, I will need a couple of tabs, I’ll specify)
* Reverse dog leg brace
* Aft Metal Belly – can we do only the last 2 feet verses 4 feet to save a little weight?
* Removable rear crossbar
* Rear Cargo tie-downs – lets talk about this
* Bushing for Tailwheel bolt
* Float fittings – fwd to be Std, aft to be flush( I will get the data)
* Welded in lift rings – like the Smithcub
* Engine mount brace tubes
* Cabin X brace – we may be able to reduce the weight here a little
* Flap handle, move outboard
* ELT antennae mount
* No tabs for the BLR system
* Seat belts attached to tabs on the floor tubes
* I would like to bring my gear up and check it against your jigs to see if it will work,
if so perhaps we can work out a price to bush the tubes for the long step bolts
* Folding front seat


Hope this helps

Bill
 
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It is a little hard to see in this photo but I had Jay put a lip on the down tubes of the door. This makes a better seal in the winter and also gives a place to tuck the interior panel under thus making a very clean, neat installation that does not get pulled away when a boot is scraped across it when getting in and out of the seat.

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This is the door tube from the inside. The channel is normally a little off the tube. Mine sits on the tube and is extended down a little to allow the interior panel to be slipped under the channel.

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This photo shows the lip better. Jay seals up the door pin hole so that no water can get into the longerons or other structure. Attention to detail. Not everyone does this.

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Note how the door frame gently widens out so that the door frame and the "D" window line up. Makes for a smoother fabric line. This is the attention to detail that Javron does with all his work. This was not my idea but just the way he does things.

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This bracket is for the rear shoulder harness. Since I will be doing a fabric headliner I had to add in this to keep the harness from ripping the fabric. I did not get a weight on this but probably 1.5 oz. My mod due to the fabric headliner I plan to do. The hooks are for a cargo net. I have seen them mounted on the tube that goes between the rear wing attach fittings but that puts them too far forward so that if you have a rear seat pax the cargo net will be literally pushing on his head. Mine are installed so that the net will angle down behind the rear seat and not interfere with a passenger. Weight 1.2 oz for both.

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Another photo of the cargo hooks.

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The blue tape highlights the junction between the upper cargo door and the birdcage structure. Jay left a gap for me to wrap the fabric for the headliner, they are normally welded together. He also extended the edge of the horizontal "C" channel (in blue) for the fabric to attach to. Weight less than 1 oz. Note the upper right door corner to structure has a small tab welded in for rigidity.

More later

Hope this helps

Bill
 
Bill, I want to bring attention to the nice big upper baggage door..looks like it goes "2 ginger bread frames" aft. Can we get a photo of it??

I've been thinking about a large, 2 ginger bread frames-long upper baggage door for some time. The gPeppard gang have had HUGE upper baggage doors on their -12's, and it is a worthwhile mod.

Thanks for your efforts.
 
Wow Bill, you're flying now! It'll be done in no time. Plus, you have the experience to do it well and fast.

Looks fun; makes me want to do another one.

You should grab all your tail feathers and bring em down to Pierces' for the seminar and cover em. It'd be a good refresher and you could bring them home covered and even painted.

Congrats on the big start. When will the wings be ready to put together?
 
Very, Very nice Bill. I like the detail he puts into his frames. If I was building an experimental PA-18, I would talk to him. After seeing his work in person and speaking with him, It would be hard to pass him up.
 
Jay and Carol - Careful what you offer cause I'm planning to take you up on that offer. It will be fun. You can fly the Hatz on your breaks. :lol:

DW - See ya soon

Dave - I took more pictures of the upper baggage compartment for you but left the disc at home. I'll post them when I get back home


I ordered my engine today from Bart at Aerosport Power. It will be a rebuild as opposed to a new ECI or Superior build up. 0-360 with 8.5 to one, early 60's wide deck conical case, hollow crank with the cut out flange, Lyc nitrided cyls, new Superior sump, Dual Pmags, B&C 8 amp Alt, Flywheel pulley machined off, and Bart blueprinting magic. Yahoo......

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I decided to go with two independent inertial shoulder harness reels. Thus getting rid of the neck pinch shoulder harness inherent in the "Y" shaped harness. Extra tab weighs 1.4 oz. The extra reel will also add some weight. This should make the front seat shoulder harness much more comfortable.

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Dual reels necessitates moving this tube back a little so it does not squeeze the harness back together thus negating the purpose of the dual reel set up.

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This is the cabin "X" brace everyone talks about. It is normally 7/8 tubing. I felt this was overkill and we reduced the tubing size to 3/4. Saved 4.51oz. The factory had one 7/8 tube. By putting in the second tube and making the "X" you effectively cut the "Beam" in half which significantly increases the strength in compressive failure. Thus we don't really need to stay with 7/8 tubes.

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I intend to lengthen the bottom of the stick 3/4 inch. This causes interference with the bottom stringer. So we terminated the stringer and built a small box. This will give both clearance and also a place for an access plate. This gives more aileron travel per associated stick input.

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Another view of the torque tube/stick box.

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These are the tabs that the seat base bolts into. We extended these about 1/2 inch higher so the seat bolt will not end up half under the floor boards making the seat really hard to remove.

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My extended baggage floor will rest on the lower longerons so I could either build a tunnel for the elevator cables or run them under the floor. These are the pulley brackets that will allow my cables to run under the floor. This mod saves the weight of building the "shelf" for the extended baggage. I did not get a weight from Jay but will try to do so.

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The cables go in the hole and the stringer goes on the bottom.

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Brackets for the cargo net tie down rings. 1 oz and 1.2 oz.
 
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ELT antennae mount

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Mounting brackets for electric trim. 2.055oz for both. Trim motor weight 14.995 and coupler weighs 1oz
total trim weight back here 18.05 including nuts and bolts.

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Tabs for the trip cut out switches. .967oz

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Second tail lift handle. 1.750oz

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Box tail brace. 6.1 oz. This can also be done in an "X" shape and or an "H" shape. I doubt it makes much difference structurally.

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Brackets welded in to allow a place to bolt in lead weights to adjust CG. The liner tubes in this area were extended 6" to strengthen this area. Liner tube extensions = 4.45oz and brackets = 4.55oz.
Most cubs with 0-360 (and even 0-320's) are at the forward edge of the CG limit when empty with just pilot and fuel. The way we most often fly them. The airplane handles and flies much better when the CG is near the aft limit. You can load a bunch of gear in the baggage compartment to try to get the CG further aft but now you are 200 pds heavier ( and all that weight will slide forward when braking hard), or you can drop 20 pounds in the tail. It is great being experimental. Certified guys can't do this type of stuff. Guys that have built and flown model airplanes will understand the significance of the CG on handling.

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Water rudder bracket tabs. Flush mounted to clean up the fuselage and lower longerons.
No weight on these. Will try to get it.

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Another shot of the water rudder bracket.

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Tabs for extended baggage floor ( not all are marked)

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Float lift ring brackets.

More later

Bill
 
Hey Bill, You have really done your homework on this project. Every post you have been making, I say to myself, that is a good idea. I didn't think there was anything else to be done because I thought that you had touched on everything..until I see your next post. What else is there to improve on? I guess I will have to wait and see. The hard part for me is trying to keep up on all this stuff. You are going to have a very nice little plane and I hope to see it someday!
 
Wow Bill! Very nice fuselage. Keep posting pics with weight. It really helps for a guy like me building my first plane.
 
Thanks Kevin. I'm still learning.


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Dave, perhaps this picture will help. This is the upper baggage door frame. Note the lip on the inside edge. Helps keep water out when flying through the rain. Rather than just one turtle deck former size this is 1.5 formers. Bigger is better but in my case the upper baggage area will not be stressed for heavy stuff but mostly engine and wing covers for winter flying. It is also much easier to access while camping so makes a good place to put stuff you want to get to often. A lock on the door is also handy for valuables.

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We made the frame from open "C" channel so I could put nutplates in to attach interior panels to.
Tough to see in this photo.

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On a certified cub this piece is done with stringer material and it can create a bulge here. Jay welds in this piece and insets it on the center tube so that the fabric flows better.

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Normal cub has two tabs here. I figured one was enough. My last kit had none and that was a little awkward.

I'll post some more later in the week.


By the way, Javron also makes both the round and square carburetor air boxes and they are very nice and reasonably priced.

Bill
 
Hi Bill, I just measured and weighed the standard Lycoming sump and also the Superior cold air sump. Superior:11 lbs 4 oz Lycoming:11 lbs even
The Superior sump is 6 1/4 inches tall and the lycoming sump is 4 7/8" You may want to consider going with the Lycoming sump so that you can get a standard cowling on it. You will also have more options on exhaust ect...
 
Bill, thanks for the photos. great Stuff!

Whatcha gonna do fer where yer RUDDER CABLES go through the baggage area?? I'm skeered 'a some cargo pinching 'em.

I've run them inside a plastic housing in this area. Have been thinking on the next airplane also running the ELEVATOR CABLES under the floor inside plastic housing also....negating the use of pulleys or pulley brackets under the floor.

Will be interested in how your engine shapes up. Way to go..on the lyc. cylinders, I think. Not sure if I could hold the build at 8.5 to 1 Compression Ratio....having tasted the "energy drink":)
 
Most cubs with 0-360 (and even 0-320's) are at the forward edge of the CG limit when empty with just pilot and fuel. The way we most often fly them. The airplane handles and flies much better when the CG is near the aft limit. You can load a bunch of gear in the baggage compartment to try to get the CG further aft but now you are 200 pds heavier ( and all that weight will slide forward when braking hard), or you can drop 20 pounds in the tail. It is great being experimental. Certified guys can't do this type of stuff. Guys that have built and flown model airplanes will understand the significance of the CG on handling.
Thanks for bring this up Bill. I have been beating this drum for years and it seemingly has fallen on deaf ears. Even the certified guys can do this with minor properly worded paperwork.
 
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Is this tab only for holding the wing root interior finish??
 

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I intend to lengthen the bottom of the stick 3/4 inch. This causes interference with the bottom stringer. So we terminated the stringer and built a small box. This will give both clearance and also a place for an access plate. This gives more aileron travel per associated stick input.

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Another view of the torque tube/stick box.

Wayne Mackey told me about boxing under the rear stick where the aileron cables attach some years ago. I build it to fit a stock Piper inspection plate like is on the covering drawing. Another advantage to it is that it acts as a dam to keep stuff from rolling underneath and getting jambed in the bellcrank and you don't have to work around the stringer when installing hardware etc.

Great pictures and ideas Bill. Why not do a "V" structure rather than an "X" in the top deck? Most of the later designs incorporated the "V".
 
Oli, if there not covered a lot of special sized baggage will fit in those holes. I also have a plastic container that fits in there real nice. Saves alot of fumblin around.
 
Bill, I love that frame. I've been pouring over your details, I like the adjustments. Very well thought out, and narrow body to boot. Perfection!
 
Bill, what are you doing for an extended baggage?

Definitely see about the Randy Apling baggage. Your being a 'weight-weeny' on all this stuff, you should be able to appreciate it.

..love the inside ELT antenna. Husky's have that, and it's good.

SteveP., I dunno about the "v". I want to truly "box", that area by crossing. If you 'V' that bay, you have to make a choice whether you can accept the forward 'spar carry-thru' or rear 'spar carry-thru' to deform. ......in my thinking.

Bill, 2 inertia reels for shoulder-harness? Hmmm?
 
PS, did you think out the rudder cables sheathing, or some other idea?

I am impressed with the super-increased level of thought that this WEbsite has brought out in the SuperCub community since it's inception. Truly, the community is 200 percent better-informed than it was 5 to 8 years ago.

Your sharing this stuff in the manner you have will heighten the spread of that knowledge and thought. Again, Thank You for sharing, again:).
 
SteveP., I dunno about the "v". I want to truly "box", that area by crossing. If you 'V' that bay, you have to make a choice whether you can accept the forward 'spar carry-thru' or rear 'spar carry-thru' to deform. ......in my thinking.

I think the "X" brace is a fix for the original design. The Pacer, Tri-Pacer and the Husky all used a "V" and those designs came later after the J3 and Super Cub. I have a "V" braced airplane here that hit the ground so the wing is flat from the aileron to the fuel tank. Cabin is in tact. With the "X" you still have a long span between attach fittings even though part of those compression loads are being transferred through the "X".
 
So maybe it's all about that bay "racking" instead of my concern for buckling of the aft carry-thru since the "V" centers on that carry thru??

Strange to me, but also, unrelated, is that every Husky I've seen that went upside down has had the top-deck deform, but I've seen lots of SuperCub's that went on their backs and NOT all of them have deformed. I dunno! D
 
Bill, what are the first five or six steps you will do once you begin building up your Cub? I need to develope an order of construction on paper like most of you builders all have in you heads. Thanks. Greg
 
Dave

The rudder cables will be boxed kinda like this..............

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Regarding the engine - I would love to do 10 or 11 to 1 compression ratio but I am concerned about the future cost of Avgas. I am not so worried about availability (I think there are enough rich folks flying pistons to keep it going) but the cost may go to 8 to 10 dollars a gallon. If autogas is near 3 dollars a gallon that just makes "high compression" too expensive for me. Plus my mission (hopefully) will be on floats where avgas may not be available. Bart will still do everything else to the engine. The only thing lacking from all the big hot rod motors will be compression ratio and 20 pounds.

I definitely agree with the advancement of the SC community via this website. All these ideas came from SC.org and folks like you, TJ, Crash, StewartB, Kase, DW, Skup, Olsen, Peppard, Pierce, Mackey, Keller, etc etc.

Olibuilt - Yes that is just to attach a cover panel. It does make a nice cubby if you desire.

Steve - I did in fact consider the "V" brace but felt that a 1.5' beam would be stronger than a 3' beam. Further the "V"was going to interfere with the shoulder harness installation. I am no engineer, that's for sure, so the "V" may be stronger. I don't know. I thought it was done to open up the attic and to provide more headroom for the pilot, rather than structural.

Greg - 1 inventory and weigh everything. Once you start to assemble things you can't weigh them unless you
disassemble.
2 Check fit. Tail feathers, Trim, gear etc. You are just looking for the bigger issues now so parts can be re-welded
if necessary.
3 Make all the interior panels
4 Get trim installed and working
5 install controls, brakes, etc (remove for covering)

There is a lot to do and sometimes it has to be done in order and sometimes it just has to be done, and order really does not matter.

Thanks for the inputs gents.


Hope this helps

Bill
 
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