Widebody Super Cub Project

[mrunia]

About me
My name is Max Runia, I'm from Meridian Idaho, 27 years old. I'm not a pilot yet so I'll be pursuing my PPL + tailwheel. I'm a senior software engineer.

About my project
- I purchased the fuselage, empennage, and landing gear tubing kits from VR3 Engineering. The tubes are pre-bent and coped ready for jigging and welding.
- The wing kit is from Javron, it's the squared off wings with 24 gal tanks purchased from another member here. Hopefully be getting those in the next few weeks.
- engine, avionics, covering, etc,. is still undecided.

Open questions (to start)
- Left side door - what are the pros and cons?
- Where to keep a build log - I have an EAA account and started a build log over there, is there a better way / place to log my build?

 

[mrunia]

Here are some photos from me jigging and tacking the vertical stabilizer and rudder

 

[wireweinie]

Boots!

Web

 

[aeroaddict]

I didn't know software engineers could weld! ;-) Looks like a great project. The local EAA chapter is active and meets at the Nampa airport if you were so inclined.

For a build log, I just wrote down what I did for the day in a typical journal/log book. Took some pics along the way with my phone. When the DAR inspected the plane, he didn't ask to see a log or pics. Your experience may differ. Even when going down to the local FISDO for my Repairman application, boxes in tow with all the documentation, they didn't look at the logs.

So I guess it varies from inspector to inspector, but I don't think I would spend a bunch of time on a really nice build log, spend that time building!

And to Web's point, safety first. Hate to get hurt and slow the build down.

 

[stewartb]

Have you chosen a DAR yet? Life at the end of project is easier if you know what he'll want to see.

Left side doors are popular with float planes. I rarely used mine when I had one. I think a big, swing-up window is more useful. And it doesn't interfere with throttle, trim, fuel lines, and flap handle.

 

[mrunia]

You are right about the sandals, I think the covid work from home has got me too comfortable. I will make sure to wear my work boots when out in the garage.

Have you chosen a DAR yet?

I haven't, I just looked on the faa site and looks like there is one here in Meridian named Tim Wilson. Looks like he is a DAR-F capable of (57 – Amateur-built propeller-driven airplanes and powered or unpowered gliders), what is the difference between DAR-F 57 and DAR-T 147? Will either work? Is one better than the other as far as cost or ease of paperwork or anything like that? It will be a few years before it's done I'm sure but good to plan ahead.

aeroaddict is there a DAR you'd recommend here in the area? Also I would like to come to the monthly EAA meeting, I reached out some time ago but was told the monthly meeting was cancelled due to the virus, would like to come if they're back to meeting!

For the left side door, I don't plan on putting floats on it but will likely weld on the float fittings just in case. It seems like structurally the left side door would remove some of the strength of the frame, also I watched some of Bill Rusk's video of his Alaska trip and it looked like he just walked around to the other side via a wire between the front of the floats. So maybe it's not even too valuable. I do like the idea of having a flap handle up top like the carbon cubs, but the rest I'd like in the traditional locations.

 

[aeroaddict]

Max, I sent you a PM.

 

[RVBottomly]

As for the building log, I'm with aeroaddict. I use one of those bound "composition notebooks", 8 1/2 x 11, and make sure its in a closed drawer while working to keep sparks and metal bits off it. It's still a little greasy, but that just adds to the authenticity, I think.

I like pen and paper--I use the right side to record time and task, and the left side serves as a sketch pad or place to jot down calculations, etc. Pictures at various steps, too.

I never understood the web-based approach. When I'm done scorching myself torch-welding or tired from sanding, etc., last thing I want to do is sit at a computer and try to reconstruct what I did for the day.

Carry on! One of these days when I get some free time, I want to do the southern Idaho circuit--I'd like to stop by and see your project.

 

[stewartb]

My DAR never looked at my “builder’s log” or any of the thousands of pictures I took. He did inspect the airplane with a fine toothed comb and offered advice on what would be better, and I corrected every one of those items after he issued my airworthiness cert. That was a fun day, and not at all what I was told to expect. Build the plane. Fill out the forms. Do the inspection and accept the criticism. Have fun. This is the best part of aviation!

 

[supercrow]

When mine was done the DAR spent as much time on my log and photos as he did on the airplane. About 6 hrs. total. But that was 25 yrs ago. Lots have changed since then. He said by his calculations, it was about 82% and well over the 51% required. He did ask for photos and weight and balance paperwork before he even came to look at it. Came from NH and charged me $500. At that point I had 2000 hrs. in the build. The inspection and first flights were done on floats right from my residence. It was great!

 

[skywagon8a]

I understand your comfort level with the electronics record keeping. However, what would happen if somewhere along the way an electrical disaster wiped out your records? I'm with RVBottomly, an old fashioned loose leaf note book with printed photos will be forever and totally under your control.

The left hand door would be a valuable asset if you were going to be on floats. There are circumstances while "seaplaning" that you must jump out quickly to protect the plane or grab a dock when it is just plain too time consuming to get out on the right float, run across a swinging cable on the bows, and then grab the dock or keep the wing from bashing itself on a piling while the wind is blowing you onto the rocks after your engine was shut down.

Since you are welding on the float fittings, the plane will eventually be going on floats. If you leave off the float fittings you can leave off the left door.

There are many who are promoting the overhead flap handle for ease of operation. Consider where your head may be bouncing around should you have the unfortunate circumstance of having an accident. In my mind that is a skull cracker.

 

[C-YQK]

Do the float fittings and the left door
Easy to duplicate the left hand door while you have your jig setup
Does not affect strength on left side according to all the folks in the business when i installed left door on mine

 

[mrunia]

Thanks for the input guys, some good things to think about for sure.

Currently working on finishing up tacking the empennage and then I need to build the rest of my table. I built the table in two 10' pieces which will be butted up against each other leveled, checked for flatness, and screwed together. Then onto the fuselage jigging.

 

[Steve Pierce]

If you install a left door then you have to rework the throttle position. Not worth it to me, I like where my throttle is and find left door throttle locations uncomfortable.

 

[skywagon8a]

This is the throttle in my Cub with the left door. I find it comfortable. True, it is not at the forward end of an arm rest. The rear throttle may be a bit awkward, but is seldom used.

 

[mrunia]

This is maybe a crazy idea, but I'm curious if anyone has tried converting to push/pull for controls? I was watching a video on the CC FX and it sounds like they run them through the wing struts instead of using cables. I got to fly a kitfox for a couple hours last year and the controls were very crisp, wondering if anyone's done it on a exp super cub..

 

[skywagon8a]

This is maybe a crazy idea, but I'm curious if anyone has tried converting to push/pull for controls? I was watching a video on the CC FX and it sounds like they run them through the wing struts instead of using cables. I got to fly a kitfox for a couple hours last year and the controls were very crisp, wondering if anyone's done it on a exp super cub..

Push pull rod controls require a clear straight space. At the end of the space a bellcrank is needed to change the direction of the push. Push rods move in an arc at the ends of their travel so require space. As many bellcranks as there are directions to change. It is not impossible though you may find in a Cub clone there would be more involved than just running cables over pulleys. Some light airplanes do use push rods. The ones I've seen are about 1" in diameter. That is a lot of space when compared to a 1/8" cable.
If you wish to run the push rods up a strut, the strut will have to be larger than a conventional Cub strut in order to accommodate the push rod.
Some planes use a combination of a cable system to drive the push rods.

If you choose this route, be certain to carefully think the entire system through thoroughly before you commit.

 

[mrunia]

Next Question: Covering Systems

- Poly-Fiber
- Stewart Systems
- Oratex

From my limited research so far it sounds like the poly-fiber is a tried and true solution, stewart systems is nice because it's less chemicals.. Oratex is nice because you only need to paint on whatever accent colors you choose.

I'm still pretty early on in my research but Oratex is looking pretty appealing. Anyone have a good or bad experience with Oratex?

Also please chime in if there is any other covering system I haven't heard of yet that you'd reccomend.

 

[aeroaddict]

My $0.02.

I had no experience with any of these until I build my plane, ended up using Poly-Fiber.

I checked into Oratex and actually called the guy but was unimpressed with his customer communication skills. I also know of a local cub that was covered in oratex and I was not overly impressed as the pinking strips did not match in color and wrinkled over time (plane was a single color). I do not know of the durability or how easy it can be field repaired. Not sure about your comment on painting over oratex for the accent colors.

If I was to build another plane, I would definitely check out Stewart Systems, primarily due to the fact that Poly-Fiber uses a lot of solvents and it STINKS! I'm surprised I didn't get busted at the airport with my home made paint booth.

Poly-Fiber is a great system, proven and easy to use. The plane turned out nice and the few patches I have done are easy and durable.

 

[DENNY]

Look into Superflight, it will save a lot of labor time. https://superflite.com/pages/why-superflite
Denny

 

[gntw]

My son and I have done 3 cubs with oratex with good results. Easy to repair and real tough to damage. First plane sons 12 with all new parts took 12 days to do. 240 hrs. We are doing a pa-14 this winter. We have done 6 poly fiber jobs and no more, if u use areothane paint hard to fix. My cub has 22 yr old polytone on it easy to fix but don’t match when old and faded. Will get oratex next few years. Oratex can be paint we put decals on. If u want more info pm me.

 

[DENNY]

How does it save lots in labor?

Less time in the paint booth.

Poly-Fiber

Glue on the fabric with our Poly-Tak fabric cement; tighten it with the heat of a calibrated clothing iron.
Brush on a coat of Poly-Brush fabric sealer.
Riblace, then apply gussets and finishing tapes with more Poly-Brush.
Spray on two more coats of Poly-Brush.
Spray on three cross coats of silver Poly-Spray to block ultraviolet radiation.
Spray on two coats of top coat paint, either Poly-Tone or Aero-Thane.



Superflight
Glue on fabric, tighten with iron
Two coats of primer/filler
one -two topcoat.
DENNY

 

[Gordon Misch]

I heard there was a problem with Oratex STC. What's the status on that?

 

[Hardtailjohn]

I'm partial to Stewarts, but then I did a lot of the work on it in the 90's. It's good stuff.
John

 

[skywagon8a]

The Stewarts is particularly nice if you are doing the work where the fumes can leak into your home. There are none.

 

[skywagon8a]

Back in the day, Irish linen and Nitrate dope was the best producing 15 or more years of life expectancy. After that it was wise to take it off for a through inspection. Now with lifetime fabrics, there is never an excuse for a good inspection until it is too late under normal circumstances.

 

[aeroaddict]

Good to know about Oratex, it is really attractive from an application standpoint. I really wanted to try Oratex but could not make it work out. Maybe next plane. :smile:
Labor time wise, I would guess Oratex would win.

 

[mike mcs repair]

Look into Superflight, it will save a lot of labor time. https://superflite.com/pages/why-superflite
Denny

Not!

That’s the stuff the customer chose for current project definitely not time or labor savings in that stuff. But that’s what they try to sell you it as. And getting it can take MONTHS!!!!

Polyfiber or dope is best

And there’s not a chance I will ever use oratex, too crappy looking, and you must wax it


Sent from my iPhone using SuperCub.Org mobile app

 

[wireweinie]

Back in the day, Irish linen and Nitrate dope was the best producing 15 or more years of life expectancy. After that it was wise to take it off for a through inspection. Now with lifetime fabrics, there is never an excuse for a good inspection until it is too late under normal circumstances.

I was taught the same thing when dealing with Razorback (fiberglass) covering. It would last so long that it needed to be removed from time to time, as the structure it covered might corrode without being discovered.

Web

 

[skywagon8a]

Razorback was durable and heavy. The wings on one of my Bamboo Bombers was covered with it.