J-4 project-3.14159265359

Almost a step forward, I first attempted to tack the mounts of the control sticks onto the fuse, but could not get them to stabilize at all. With everything mounted on ball bearings it just could not be made to sit in place.
So I used a piece of 1 X 4, mounted on the milling machine and made a jig for locating the control stick mounts. Last night I set the mounts in place then walked away happy.
So this morning I went down, fired up the Tig and did the initial welds for the mounts, now I am happy again.



Cool, now I can mount the sticks for the first time, granted the fuselage is upside down and hanging from the rafters I can not sit and fiddle,



But now, and only now I find I made the mounts such the the torque tube is a half inch or so too low. The top of the tube was to be just a touch below the floor level which allows proper geometry of the aileron cables and clearance to other systems. Oh well, cut it apart and make things right.

I decided the mounts for the control stick will be fine as they are, not sure I intended the torque tube to be where it is but there is technically nothing wrong with it.

I got back to making parts. This entailed doing some detail drawings, machining a few bits and the welding.
What I am concentrating on now is making the mounting points for the pedal assembly. Since the seats are fixed I have chosen to make the pedals adjustable. It comes down to adjustable pedals are less of a weight gain or safety hazard than a movable seat that does not have proper crush structure under it.

These few parts have quite a few hours in them but they are a start.


Now I have the fuselage sitting upside down on the shop floor. The lift eyes on top of the front spar are nice since they are threaded into the structure and allow for leveling.
Basically the parts made today are the rectangular tube along the centerline, the two dowels seen up front are for the center mount for the brake torque tube. Aft of that the pin hanging down is the center pivot where the pedal structure will be mounted. Next will be to make some tooling to align the outer pedal mounts, then to fabricate that structure.
The pedal assembly will be a L&R cradle mounted on Delrin bushings. These will locate the pedals which will utilize ball bearings for all pivots.
I have yet to decide if the pedals will be fabricated in stainless or if I will spring for all Titanium tubing. That might be decided if I am buying a new camera for Oshkosh this year or not.

Here is a screenshot of the pedal assembly as being built. Lots and lots of little parts to be made.



I got a few hours in on this making parts and doing minor but needed revisions, basically updating where I left off on these parts drawings a few years back.

Another screenshot,



Looks like the image gets scaled in reverse with the rudder being proportionally big with the engine being way too small. Damn software.

Today's task was more detail design work followed by making the outer brake torsion shaft mounts that mount onto the frame. I did take pictures but then got busy preparing for our first planning meeting for the B-17 tour we have coming in September. If it's not raining that weekend I may bring this frame over for people to look at.

A little more being done,
I need to mount a mixer connecting the left and right pedals. This system will allow the unused pedals to be stowed forward reducing the chance of un-trained toes getting to them or the brakes.

Earlier I welded in a cross box tube that has two thin wall dowels which an AN-3 bolt can pass though to hold some brackets in place.
This morning I placed a chunk of 1X4 in the mill and drilled holes so I have an accurate jig.

This mounted in place over the existing dowels allowing me to drill through thin wall ¾ tube.
These holes will get thin wall stainless sleeves as I utilize in all through tube holes.

CharlieN said:

This mounted in place over the existing dowels allowing me to drill through thin wall ¾ tube.
These holes will get thin wall stainless sleeves as I utilize in all through tube holes.

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That's an idea I hadn't run across. Is there an issue with dissimilar metals?

Vic

RVBottomly said:

That's an idea I hadn't run across. Is there an issue with dissimilar metals?

Vic

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Yes and no,
The Stl tubes weld into the 4130 frame using ER312 rod. The stainless to the steel is no concern with that alloy. Where it may get moody is if the dowel locates aluminum as I will have in some areas, a good anti seize should be used since Stl & aluminum do not play well together. Best if the aluminum is anodized or acid-zinc plated.
Some of what the dowels will locate are made in engineering plastics, no issues here. I will also be mounting all the control system bellcranks and pulleys over stainless. These are generally not an issue since many bearing are plated, but should use an antisieze as well in not to insure conductivity between parts.

The dowels are inserted here.


And in front of those is the aft brace of the inner pivot for the pedal assemblies.
What might look out of alignment in the upper pic, that ½" tube is actually on the centerline, it is just the ¾ cross tubes are asymmetrical due to the differences at the firewall with the fittings for the swing out mount.

Up front in this shot is the inner pivot for the pedals to hinge on.

A few more bits, I now have the mounts for the relay tubes. I have machined the arms for said parts as well and next will machine the ends of the tubes where they will fit in the ball bearings.
Not sure how far I will get today since I ave to finish some documents to hand out to my workers for the upcoming B-17 tour we are hosting.



I might change the material of these blocks before the plane flies since the UHMWPE was selected when the tubes were going to ride directly in the block, but I decided to go with ball bearings so the super slippery plastic is not needed as much.

My next little tool, I need to locate the outer pivots for the brake shaft. The two master cylinders are on the outermost section of the firewall structure. One left and one right.
I had shown the inner mount located on the centerline. Now how to accurately mark where the center of each outer mount needs to be.
Well a few minutes in the lathe to turn up a holder for a .223 bore sight laser. This mounts up sweet.

My next task has been to get the brake actuator parts underway. I did not take pictures of using the laser setup to layout the end brackets but the system worked well. Those parts will show in this next set of images.

The brake pedals will drive torsion tubes to apply force to the masters, I chose to stay with stainless rather than go with Ti. Just not enough weight saving on these small parts.

I will start here with the short arms that link to the masters, these got drilled, reamed and rough milled to shape.


Then dressed on my 18" disk sander,


These bits then get slid over the ⅝ x.020 tube that has machined ends pressed in place that fit in the end bearings.




The aluminum angle end brackets will later get dressed down to shape but for now I want to see if they need to be larger than expected should they hang something else. The brackets are drilled and tapped and when actually mounted will get double nutted with MS 21042 nuts.

I decided to spend a few hours and make the upper rear shock mount and get it tacked in.

Back up front today. I made the outer pedal mounts and have them partially welded in, These two shots show the machined aluminum tube that is retained with a 5mm threaded rod through the middle. Then we have the outer pivots followed with all three legs on each side.


The outer mounts held their position through the initial welding which is nice of them.

After a 3 point roll it landed outside. Always a good feeling when you can step back and see it.

No productive work done other than detail design studies. I have set a seat in place. last time a seat was sitting in this the frame sub assemblies were held together with bungees and tie down straps. Dang tubes would try to skewer you each time it came tumbling down.
So, I have raised and lowered the seat, not truly sure where I will want it since one's perspective looking out of a bare frame does not let you feel what it will be when an actual cowl and wings are on.
Seat down low you can look up from under the wing, but view over the nose will not be so good. Raise the seat to high, see over the nose fine but not up much to the quarters.
I expect I will make the seat movable, not simply but how I build race cars, it can be moved but takes tools and time.

One thing I determined, I will add structure along the centerline between the pedals. My bad right leg is prone to roll out and I vision I could possibly get on a left side pedal by mistake. I have heard of this happening resulting in a crash, I can prevent that for very little time and weight.
Since I am going to the point of being able to stow the off side pedals so a PAX does not get the brakes when it might not be a good thing, this sure will not hurt and might prevent them getting a foot on my side pedals.

Another determination, The lower door will have a curved profile, a nice thing. But I was stuck at the top of the upper door, this swings up. I would like a root fillet as even a factory J4 has.
I determine that the hing line does not need to be right at the top but can be down and inside a bit such that the very top of the door swings inwards away from the fillet. It will be tricky to get right but it will be sweet and clean when everything is closed up but still allow the window to be full open in flight.

I know Glenn would never get in this plane if it could not fly opened up.

Back to trying to find floorspace in my shop.

An old piece of aluminum flashing comes in handy to visualize the firewall.

Hey Charlie - know anything about the fuel gauge in the 16 gal fuselage tank? Will it come out without removing the windshield?

bob turner said:

Hey Charlie - know anything about the fuel gauge in the 16 gal fuselage tank? Will it come out without removing the windshield?

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Not sure, it has been way too long since i have looked at my original and for some reason I do not have pictures of the front tank. It is here, but I bet Glenn G. "Cubdriver2" can answer that best. Between his and all the Coupes on Bob's Island they sure have learned.

I want to form the curved edges of my mock-up firewall since this will be in use for some time. So I need some round wood discs that I can replace the top of my drafting stool that just never seems to be used anymore.
As I stand this morning outside the shop door, staring at my anvil, then walk inside, I realize I have dozens of different size automotive brake rotors from 14" diameter down. I can bolt these onto the anvil and rap on them to my hearts content.

Funny how I was looking at some old rotors just a couple days ago, wondering what I'd use them for. Now I know!
Vic

Sent from my SM-J320V using SuperCub.Org mobile app

bob turner said:

Hey Charlie - know anything about the fuel gauge in the 16 gal fuselage tank? Will it come out without removing the windshield?

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Bob, mine does, it's just a big knurled nut that compresses the flange of the gauge to the bung on the tank. Once free you have to rotate the gauge a few ways to clear the windshield

Glenn

RVBottomly said:

Funny how I was looking at some old rotors just a couple days ago, wondering what I'd use them for. Now I know!
Vic

Sent from

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I am in the process of rough forming the edges of the FW now, the curve of the upper radius is 6¾" which happens to be spot on for one of my tube bending dies. One frustration is I appear to no longer own fluting pliars, looks like someone else wanted them. Glad I am not making finished parts.

It ain't pretty but it's well a tool that represents my firewall.


The cross cut was done with a utility knife, what I am doing here is depressing the center of the FW to make room for accessories.
Granted there will not be much on the back of the engine, maybe a mag, a gear driven alternator and a few oil lines. Next owner may need more room though.


What may look odd to many is the upper section of the FW does fold forwards. In order to carry the added weight of a Lycoming I chose to move the FW back a few inches and utilize a rather short mount. This coupled with the longer motor and prop spacer places the propeller in the original relationship to the wing while moving the increased mass back more than 6". If the numbers play out right this should not be a nose heavy pig.


So the reason for the forward lip, this allows the windscreen to not need to be stood up steeper than original. The plane will never be a speed demon but it will not be slow either.

Sure all the hard to get at finicky spots to weld are what I have to do. Where is that 30 something Tig expert when I need one,I used to be him way back in time.

Charlie, This picture brings to mind the accessibility to the mags on my 7GCB as being very difficult to the point of having to learn a lot of new words just to take off the point cover plate. The later 7GCBCs moved the engine forward to improve the situation. I would hate to have to pull the engine just to inspect the mags during an annual.

skywagon8a said:

Charlie, This picture brings to mind the accessibility to the mags on my 7GCB as being very difficult to the point of having to learn a lot of new words just to take off the point cover plate. The later 7GCBCs moved the engine forward to improve the situation. I would hate to have to pull the engine just to inspect the mags during an annual.

Click to expand...

Yes but if you look at the image above that you will note the mount swings out to the starboard side. Another view.

The fuselage was built such that the mount hangs on two vertical fasteners on the starboard with three dowel and sockets that 3/8 bolts thread into to retain the assembly. Nuts can be then threaded onto these bolts from inside the plane such that they are "double nutted"

Here is an image of the firewall structure with the engine mounting provisions.

The plan to build a true experimental replica is the way to go. BTW, I fly my C-85 powered J4A regularly and I'd be glad to come up to Rutland from 7B2 to show it off. I'm trying to sell it, looking for a reasonable offer or a swap for comparable condition and equipment C-120.

The J4A with a C-85 will hit 100 mph but with that big wing (36' 3") it takes smooth air to do it while holding on to your dentures.

Also wondering why no one mentioned going the DER-V route for modifications. I worked with Terry Bowden (barnstmr@aol.com) to get approval to install Grove master cylinders to match the Grove disk brakes on my J4A. It was a very straight-forward and reasonably priced process. And, it's great to have good brakes maneuvering that big wing on a crowded ramp.

Would love to see it,
Curious if you get a bit from the guy out West.