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J-4 project-3.14159265359

I made a simple jig to locate these spindles and tacked them in place.
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The aft end of the jig was spaced down from the elevator rocker to allow for a straight pull on the cables.
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Now the rockers can be put in place for a trial fitting.
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Back during the change of the year I kind of felt the need to get something done on control system parts. To get a parts done I deviated from my drawings and simplified the torque arm for the elevators at the control torque tube. The simplified part sure looked nice.
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This arm was formed from a piece of ¾ square tube, drilled, cut, then ground, it is shown with a ½ tube as a jig to align it for welding in place.
It sure looked nice but I was not getting the warm and fuzzies. Granted the fuselage was upright and low the the ground such that I could not get my eyes on it.
Sure enough, once the fuse was flipped over and I was jigging the rudder rockers it was very clear to me I will have a heavy interference with contact to the left rudder rocker with aft stick.
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I think I took the pictures in that session deliberately not showing the mistake, kind of like hiding from it.
But the rework of the arm came to me during a redeisgn while sleeping so today amongst other projects the arm now comes aft and down as I had drawn it.

Yup, one should not deviate from the plans especially when you draw your own plans, no pictures really show the issue but the original arm was to com back and down, kind of like this.
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This might not be the final part as it is a bit rough but works as a proof of concept for now.
 

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I'm still trying to visualize how the rockers work. You have pushrods going somewhere....

I'm assuming you won't have the typical cable attached to the rudder pedals?

Good point about deviating from plans, even your own. I don't really have that problem because a lot of the plans I'm using demand creative deviation--which I suppose is part of the "plan."
 
I'm still trying to visualize how the rockers work. You have pushrods going somewhere....

Correct,
Each side of my pedals are adjustable, this rendered image shows where I am going.
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From the rudder, cables come forward which connect to the outer end of the rockers. (not shown)
The rockers are in the lower left, pushrods going forward under the landing gear spring. These attach to a weldment of two more arms. Bellcranks might be the right term. From these are two sets of pushrods going forward to each pedal. These pushrods are each a two part sliding assembly, explained soon.
The pedals on each side are mounted on the yellow or gold brackets which pivot on the fuselage allowing the pedals to be adjusted as desired.
This adjustment I expect will be done with a hand knob running on an Acme threaded rod.
Being the pedals can move so far forwards as to be stowed the four short rods are a two piece sliding assembly such that a stowed pedal is essentially disconnected or call it disabled such that it will not affect the other side pedals.

The bellcranks look like this, all these parts as with the rockers ride on ball bearings.
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The pushrods will be carbon fiber with aluminum ends, not that they will make up for the weight of the two steel bellcranks.
 

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Little bits of pedal parts, The past week I have spent some time doing detail drawings for the pedals. Got to the point of locking down the design and making parts. Here are a handful of bits that will become what is shown in the rendering in the post above.
These are the inner brackets, doublers for the ends of thin tubes and the outer pivot for the adjustment mechanism.
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The rendered pedal image a few posts above is not current, this one is. At least today :roll:
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I had not had a real grasp on how I wanted to fabricate the inboard end of the outer control pedals. Overnight when I pretend to be sleeping I am generally designing parts or analyzing structures. Last night it was this inboard arm, so this morning I got to it.
I knew I wanted the rod end in double sheer as is normally done but did not like the non self jigging aspect of multiple parts, so I proceeded with some trusty rectangular tube, This will take a ¼ rod end in the bottom, a ¾ torque arm in the middle at a 10.3° and I need a 19mm hole for a ball bearing to be pressed into up top, so.
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Then back on the mill the top hole gets reamed followed with a session on the disc sander for dressing the outer shape. To guide the lower curve I use a washer as a template with a generic bolt to center it.
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Next session will be to mill out the bottom for rod end clearance then deburr the parts.
 

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Bummer, Charlie. Photos aren't coming through for me.

Vic

Edit--now they show up.
 
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Interesting, I replaced one in the post above that one cause it had disappeared. Now these have as well. These are loaded directly from my camera. I tend to wonder if somehow they are slaved from my computer? I would not have thought so. Lets see.
 
Well, not that I wanted too but it's out to pasture for it. Need to replace a growling wheel bearing in a car.
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Ok, it's actually into the garage with it.
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Dang, over 600 feet of tubing and I do not have material to make a design change to the rudder spar. Well that wont get done this weekend unless I make it in .028 wall since I still have a fair bit of it. Being the spar is made with two tubes side by side, humm.
 
The fuselage is back in the shop, for a few days at least. I determined some time back that the vertical fin was to be 3" taller, so I spliced an extension on top of the existing spar. This allowed me to move forward and make the top rudder pivot and tack it in place.
The welding on the extension is still to get rosettes added.
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The top pivot consists of a machined stainless pin welded into a .095 plate, here it is clamped on top of the spar.
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And initial welds and trimmed the front of the strap off since all lines up sweet. The pin is counterbored 5.8mm with a tiny through hole to allow insertion of a laser that will now be used to insure all 3 hinges align up as well.
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And a bearing set in place.
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That little 6mm laser, it is not worth Poo. Better part of 3" off in under 4'. No wonder my wife couldn't hit anything but dirt and limbs with her 38. Luckily not my limbs.

So I brought a 223 laser down to the shop, I know it is accurate. I turned up an adapter and corrected for how far off the first laser was.
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The red dot is on the front lip of the lower mount.
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Batteries were going flat fast while I went upstairs to grab the camera so the dot is far from brilliant.
I can not do much more till I make and weld in all the bracing for the spar, and dang that lower mount tab looks nasty where I had to cut it off to move backwards a bit.
 

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Waiting on parts for another project, might as well rough out the rudder spar.
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Guess I should have brought the camera down to the shop earlier.
 

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The past few days turned out to be 37Hrs re-drawing the tail feathers. I had originally penned my own airfoils which is essentially fine but I wanted to do a design study working with NACA 4 digit foils. Not something I care to use on the wings but still commonly used on the tail. The foils I am working with range from 3% to 6.7% thick with a varying amount of camber especially on the horizontal.
I am drawing more than one set of structure, one using the common 3/8 tube on the trailing edge.
I also want to consider rolling the TE tube to be oval shape as done in the past on some Wacos and a few other planes.
And the third set will be with a thin fabricated TE, probably composite ribs and trailing structure.
I will say though, Thursday was a marathon drawing session with over 20 hours with 9 drawings open. My mind was pretty damn baked this morning.

About the only "work" I got done was bending some 5/8 tube,
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Followed with re-purposing my Long EZ nose wheel to be a temporary tail wheel on this plane.
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This swivels on ball bearings as well as most every thing else does so in this case it will have minimal affect on rudder feel.
Granted this is not intending for this plane and being a skinny 8" tire is smaller that the two other wheel assemblies I have. It will take me some time to build out the TW release mechanism and I kind of want to know if I need to be a weight weenie or need some weight back here.
 

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Will the welding rod trick work out on .035 wall in your bender?
It works well with say ¾ .035 up.
It truly helps on this 5/8 .028 but far from perfect.
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The tube closest with the rods in it is the fresh bend, to the upper right is a free bend done a year ago that requires a gusset. Both of the fresh bend tubes are the same waves, but not kinked.
The rod I used is 308 alloy 1/16 wire. I think in this tube 1/32 wire might perform better.
Another issue I think I am up against is my 5/8 work is done on an Imperial brand bender I bought many decades ago. This is my only Cast bender and my only tool that I can not get great bends on. My other small diameter benders are machined steel and all my other dies from 3/4 either I made them or the larger sizes used on my hydraulic bender were made for me on CNC tooling. They work sweet. Heck my 1 1/2 die will bend .035 with no internal support which is used in automotive work. The larger thin wall stuff must be pulled in one sweep or the tube will spring.
 

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I've filled the tube with sand for successful too-tight bends. Never thought of the welding rods - thanks for that.
 
I have used sand plenty of times, kind of found I needed to weld a cap over one end, tamp the sand in and with the welded cap one needs to just watch one end to see if the cap on the pushes out as you make the pull. I did for some time keep an oil mixed fine sand, it worked great, I think it was 5606 that I mixed in.
Long time back an elder gave me a wax that was a rather low melting point and was very firm. That worked great. Never learned what it was called or where to buy it. Only needed plastic tube caps to retain it while it solidified to work.

Being out of state yesterday for a presentation nothing more was done but this morning I fitted a top rib for the vertical fin. This does not need to be spot on the airfoil but needs to remain stable under load, as such it is made from a 1x½ .035 tube and is close to being ready to tack in place.
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I've used automotive freeze plugs the appropriate size welded on one end, pack the sand by tapping the piece of tubing then drive the other plug in and squirt it in place with the mig. Thought I'd try the welding rod method sometime since I have a lot of extra rod that is too corroded to weld with.
 
It works but I would say with smaller tube use small wire, like .045 or .035. although it may be tough getting the last few pieces slid in.
I have heard of oiling the wire but have just used it dry myself. I do not like the idea of finding oil running down to a weld when the tube warms up.
After the bend it will take Vice grips to pull the first wires out.
 
I settled into how some of the support for the vertical fin is being done. I want a high torsional stiffness and determine a Vee shape front spar will allow lighter structure elsewhere. So, I drew what I wanted and printed it, cut two lengths of 5/8 .028 tube. Cut an 11" long miter up top and curved the lower foot where the airfoil allows.
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With the tube ends dressed it is set in place.
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A little more, I also had gotten the upper hinge on the rudder made yesterday.
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And the lower hinge with rudder arms tack welded.
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And the bottom of the front spar tacked in place.
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After plowing I finished up the mid rudder bearing mount. This like many other machined parts is made from 304 alloy so it will not rust the ball bearing into place as years go by. Next will be to make the pivot pin with it's mount to go one the Vfin spar.
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The rudder was originally going to be a single 7/8 tube but after seeing the prices for streamline brace wire I redesigned the full tail and went with the wider structure that has no need to be braced. This picture shows where I reworked the top of the control horn which originally had an angle cut to weld in the spar tube but then I changed the bottom mount to house an upper bearing. There are a total of 4 ball bearings locating the rudder. One of the many running changes that required rework.
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The center rudder hinge is now tacked in place. The images here are with a jigging bolt in place rather than the pin the bearing will ride on when done. I like it, you just breath on the rudder spar and it turns to it's stop. This will be nice.
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And a better shot looking up under the top hinge.
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One other thing I think I might do soon, I kind of want to get a feel for how this sits on the main gear. not to mention if the caster angle on the tail wheel is correct. In time I will more than likely be making a composite spring gear for the mains. Right now I have been jumping on the rear of the fuselage as well as picking t up and dropping it. Damn is that Fox Shock impressive.
But up front I may make up a non usable gear from mild steel tube that I have left over from customer jobs. I can machine a few bits to mount it and bend up a yard usable gear. Yesterday this kind of started to be more feasible since I remember I have a pair of suitable size wheels and tires that are leftovers from a restoration I did decades back.
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Should look the part well enough.
 

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Today's task has been to get the bushings for the horizontal rear spar into the fuselage. I machined a pair of bushings, finish welded some brackets on the fuselage which required rolling the fuse over, got some first paint in the area. Not permanent paint but with the bushings being pressed in, they might not come out again such that I wanted the inside of the tube coated.
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I needed to finish ream the bushings since the welded tube was surely not going to be round inside. This was planed for by leaving the ID 5 thou snug.
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Now the spar can be inserted for the first time. I did have to put the spar back in the lathe to dress the center a bit but it now is a nice snug fit.
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This spar tube is 6' long, It now will get the mid elevator hinge brackets and the brace strut mounts get made for under the fuselage and outer ends of this spar. The Spar also will get inner stops welded in place so it remains centered. The outer hinges will be further outboard on secondary structure.
 

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This morning I started with verifying that the horizontal spar was square and level. We almost, measuring the diagonals from the spar ends to a fuselage centerline about 7' forward gave me about a 3/8 difference.
Remedy was insert a heavy wall steel tube into the mount bushings, slide a 4' length of tube over that tube and start pulling, just two tries and with a Stanley tape the tube is square to the airframe. Best I can measure level too.
Next was to make the centering collars for the spar, for these I bought a short length of stainless heavy wall pipe that I machined the collars out of.
First collar, this one takes the bolt that holds the two sides together through it as well as being tacked in place.
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The other side is captured inside the reinforcement and is removable should I need to fiddle with dimensions.
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And with each side slid in and the retaining bolt in place.
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Humm, my camera just climbed past 30,000 images so for the third time the image count is at 0001. Still going though. Glad I am not paying for film or slide processing as we used too, but I used to just run up 3 to 5,000 images per camera back then.
 

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