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Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)

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Old 07-09-2011, 04:40 PM
  #151  
SunDevilPilot
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Default RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)

Thanks for the heads up on the wings length! Ill check the length on the plans before I continue. If nothing else I will verify the length again before I built the second one.

Perhaps I should cut the main spars for the second wing now so I can measure them against the first wing panel.

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Old 07-09-2011, 07:20 PM
  #152  
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Default RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)

I just measured my plans and both wing panels, minus the center section and wing tips, are 42 3/4 long. They should build perfect on the plans.

Nothing major to update... I pinned the spars to the plans and glued on the ribs. Using standard PVA wood glue, Gorilla brand. The Gorilla Glue brand wood glue is really great stuff and no CA irritation. You just need to make sure the ribs wont lift while the glue sets.

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Old 07-10-2011, 01:21 PM
  #153  
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Default RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)

Progress is being made.

I cut the sheeting and glued it to the bottom of the wing this morning. Some of the sheeting, specifically the 1 1/2" stuff used for the trailing edge and Aileron sheeting was not quite consistent in dimension. I noticed this as I was fitting the sheeting prior to gluing it together. In some parts it was over 1 1/2" and some parts it was under. So... This was a little overkill of a tool but it worked perfect. Fortunately on all the parts one side was straight and true so I just set up the fence on my table saw and re-ripped the parts nice and straight. I took approximately 1/16" off each sheet to make them perfect.

All the sheeting was glued together prior to it being glued to the ribs and stringers. From past experience with basswood I knew I was not going to use CA to make the bond. I used standard wood glue to mount the stringers to the sheeting and after that set I went back and used some medium CA to glue the ribs. CA tends to wick under the ribs and makes a perfect bond.

The sheeting was also modified from stock in terms of their length. Instead of cutting it short I went full span with the trailing edge sheeting and aileron sheeting. This will allow me to cut the flaps out of the wing just like the ailerons. The sheeting at the trailing edge root of the wing was also shortened a little bit to allow the flap to come a little closer to the fuselage.

You can see the extra rib, actually 2/3 rib, I added near the root. I cut the front of the rib off to allow for the wing spar pocket to be built per the plans. The added rib will be the inner edge of the wing where the flap will end.

Next up is to create the pocket for the main spar at the root of the wing.

The wing is just finishing the drying process and once that is done I'll move on to the pocket.

SunDevilPilot
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Old 07-10-2011, 05:49 PM
  #154  
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Default RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)

Due to the modifications I have made reference the center section being a piece of the fuselage, to create a structure for the door, I had to devise a way to set the root rib at the proper angle. The plans call for the center section to be set on the wing during this process, somewhat difficult now that it is installed into the fuselage. The plans also call for much more than one degree of dihedral than I plan to use, I settled on one degree per side. In the stock form the second rib on the wing has a slot for the center spar to go through setting the dihedral. You may remember I mentioned earlier that I widened this slot to allow me to adjust the dihedral. So, the best method I could come up with was to create some shims with one degree built in. Fortunately the miter gauge for my table saw has increments of one degree built in.

I squared up a piece of wood at 90 degrees. Then I adjusted the miter gauge to give me a cut of 89 degrees and cut the shim. Two shims were made using this process... One seen on the square to help me set the root rib at the proper angle allowing it to go flush with the fuselage. The second one is seen under the center spar. The height of this shim matches the root rib where the center spar exits. This second shim will allow be to build the structure for the spar into the wing at the proper angle.

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Old 07-11-2011, 05:12 AM
  #155  
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Default RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)

Build is on hold. Looks like my kit was shorted some of the spruce spars. I placed an order with Aircraft Spruce for some more but i will try to find some locally today so i can at least get this wing panel complete. 48" spruce stocked locally will probably be a tall order in this day and age.

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Old 07-11-2011, 04:45 PM
  #156  
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Default RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)

Because I was at a standstill on the build, do to the wood shortage, I decided to go ahead and go flying this morning. While I was flying I was talking with one of the guys about the build and the issue of the missing wood came up. Fortunately for me he, John, had just want I needed to continue my build in his stockpile. After our flying session I went to his house and picked up a few pieces of 1/4 X 1/4 spruce to continue on the build. Thanks John!

I installed the upper spars and now I am in the process of installing the shear webs. I cut a few blocks from MDF to assist with the installation of the shear webs, gives a clamping surface. Just be careful not to glue them in!

I have ordered some more wood so I will use that on the second wing half when it arrives.

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Old 07-12-2011, 01:34 AM
  #157  
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Default RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)

Great story there SDP. Glad to see you have some good guys to fly with.
I was going to say, you do have a table saw so why not rip some spruce spars?
Home Depot here in NC has 2x4x12 spruce boards do they carry them in AZ?
Old 07-12-2011, 04:56 AM
  #158  
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Default RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)

I'm not sure about Home Depot having spruce here. I know they have oak and maple. I'll have to go look. That would be a great source of wood if they did.

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Old 07-12-2011, 05:15 AM
  #159  
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Default RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)

All our Home Depot store, Rona, Lowe's and Home Hardware here they have what they call lumber yards. Well, let me tell you they certainly are not lumber yards. Those days apppear to be gone as these non-spedcialist places have essentially forced them out of the market with low grade stuff for cheapies.

So what's my point, you say? Simple. You can buy all the spruce that you want from these places. But you certainly won't find anything from which you can rip a 48" long spar. It's all low grade studs, full of knots and warps.

You need what is called clear spruce - no knots along the length where you will cut the spars and relatively straight, consistent grain. Just not gonna get that from the home reno store. Look at the wood on end. YYou'll see from the rings that they're cutting trees which can't be any more than 3" diameter, which are full of twigs and little branches the entire length.

You need a place like Aircraft Spruce or BUSA for your supply.
Old 07-12-2011, 05:47 AM
  #160  
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Default RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)

Thanks Ant Eater, I haven't seen Aircraft Spruce before. I added them to my suppliers list.
Old 07-12-2011, 05:54 AM
  #161  
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Default RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)

Upon fininding the shortage I ordered 48 feet of 1/4 X1/4 Spruce from Aircraft Spruce (10 sticks at 48" long). I have ordered other items from Aircraft Spruce but never wood. I guess i'll find out how good their wood is.. With a name like theirs I would imagine it is good.

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Old 07-12-2011, 12:55 PM
  #162  
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Default RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)

Per the plans the pocket for the main spar is to be built on the wing piece by piece. I didn't think their method was the best way to go so I built mine as one piece, off the plane, and installed the complete part into the wing. The pocket is secured to the main spars on the rear. The plans call for it to only be attached to the ribs on this side. The main spar is just to keep the wing in place on the side of the fuselage, the dihedral is maintained by the functional struts, but I determined it couldn't hurt to attach it to the spars. The other side, per the plans, is attached to the spars with a spacer of balsa. I used some spruce rails which was adjusted to fit between the spar pocket and the spars.

The original design also called for the entire spar pocket to be at the dihedral angle within the wing. I just made mine completely fill the area between the ribs and between the top and bottom sheeting. The angle is set by the internal components in the spar pocket and not by the pocket itself.

The 1 degree "wedge" I made really helped with this part of the build. Alignment was simple with the main spar resting on the wedge perfectly maintaining the correct dihedral angle.

A pictures worth a thousand words.... The first photo was taken while I was constructing the spar pocket with the main spar partially inserted into the wing. The second one is of the entire assembled spar pocket installed in the wing.

SunDevilPilot

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Old 07-16-2011, 07:59 PM
  #163  
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Default RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)

The right wing is progressing nicely. The majority of the top sheeting is now in place with exception of the centermost pieces. The wing is now stable and has been unpinned from the table.

I will add the center sheeting, trim the excess sheeting from the outer rib, add the cap strips, and then I will be on to the left wing.

I conducted a test mounting of the wing with the fuselage and all lined up perfect.

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Old 07-17-2011, 01:59 AM
  #164  
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Default RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)

Now comes the hard part. Building a LEFT wing. LOL
Old 07-17-2011, 02:37 AM
  #165  
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Default RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)

SDP,
You will like the wood from Aircraft Spruce. It is aircraft certified wood. I bought 500ft of the 1/4sq spruce from them for a homebuilt project. The project is now on hold so I have a big supply for model building The quality of the wood is excellent and much cheaper the the H/S prices.
Enjoy the build!!
Anthony
Old 07-17-2011, 02:09 PM
  #166  
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Default RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)

Cap strips have been installed on the top of the wing. While doing so I came across an issue. I appears as though the stock location for the aileron servo is right in line with the struts. I plan on having the servo on it's side with the arm sticking below the wing through a servo plate. In this configuration the struts are going to be right in the way of the servo tie rod. So, I will be moving the aileron servo in one bay. I will need to add another plywood rib to the aileron for the linkage to connect to as the stock one is out of place now that the conflict has been found. Like my 1/5th scale Cub I am going to make an aluminum horn which fits the plywood plate inside the movable surface (Flap and Aileron).

Here are a few photos of the wing mounted to the plane. I am really happy to see the mounting working as it should, due to the large amount of modification I made to that area to add the door.

In the second photo you can see the root rib for the left wing still mounted to the fuselage. Gives a good view as to how the wing mounts.

It is starting to look like an airplane!

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Old 07-19-2011, 03:45 PM
  #167  
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Default RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)

It must have been a Friday when my kit was packed. I ordered some 3/32" X 4" X 48" to get started and complete the other wing. I don't recall using any of the 48" sheeting for anything but the right wing but I am definitely short on the wood. No big deal but it will make for a little delay. This wood was ordered from Sig.

Not sure on the shipping time for wood from Aircraft Spruce but the 1/4" Spruce Stringers have not been shipped yet.

Let the waiting begin!

Here is a photo of my 1/5th Scale Sig Cub with the bones of my 1/4 scale. Sig should use the building techniques of the 1/5th scale and make a new Super Cub kit in 1/4 scale!

SunDevilPilot
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Old 07-19-2011, 05:49 PM
  #168  
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Default RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)


Sig should use the building techniques of the 1/5th scale and make a new Super Cub kit in 1/4 scale!

SunDevilPilot

That's for sure!!

A good, 1/4 scale Super Cub kit is ong overdue.
Old 07-19-2011, 09:04 PM
  #169  
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Default RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)

Sig's new owners think there are no builders left. Pretty much ARFY's is all you will see from them as new.
Old 07-19-2011, 11:55 PM
  #170  
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Default RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)

Sigs new owners Know there are no builders left. Just one or two oddballs out there.
Old 07-20-2011, 12:04 AM
  #171  
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Default RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)

OK then, count me in as an oddball. I love to build my own.
Old 07-20-2011, 12:40 AM
  #172  
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Default RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)

Me too! Actually how many people are left that design and scratch build?
Old 07-20-2011, 03:58 AM
  #173  
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Default RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)


ORIGINAL: SunDevilPilot

>
>
>
Here is a photo of my 1/5th Scale Sig Cub with the bones of my 1/4 scale. Sig should use the building techniques of the 1/5th scale and make a new Super Cub kit in 1/4 scale!

SunDevilPilot
Hello SunDevilPilot,

The models in the pic look real nice.

What are the basic dimensions of each one? (wingspan and fuselagelength).

Zor
Old 07-20-2011, 09:28 AM
  #174  
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Default RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)

I do quite a bit of scratch building from plans with a little bit of re-design along the way. Have never really designed my own concept. Always seem too busy to take the time and effort.
Old 07-20-2011, 06:01 PM
  #175  
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Default RE: Sig 1/4 J3 Kit converted to PA-18 Super Cub (Build)


ORIGINAL: Zor


ORIGINAL: SunDevilPilot

>
>
>
Here is a photo of my 1/5th Scale Sig Cub with the bones of my 1/4 scale. Sig should use the building techniques of the 1/5th scale and make a new Super Cub kit in 1/4 scale!

SunDevilPilot
Hello SunDevilPilot,

The models in the pic look real nice.

What are the basic dimensions of each one? (wingspan and fuselage length).

Zor
Thanks for the compliment!

The one under construction is a 1/4 scale. Wingspan of 105" and a length of 67". The green one is a 1/5th Scale with a 84.5" wing and a length of 55.25"

SunDevilPilot


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