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

The leading edges of the Flaps and Ailerons had been installed and shaped. Next up is to add the hinge hard points to the wing and install the trailing edge. Then hinging can begin.

Again, the hand plane I purchased made quick work of shaping the leading edge stock bringing it to with a 1/16 of the final dimension quickly and without a great deal of mess.

SunDevilPilot

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

SunDevil Pilot,

Do I see correctly that you have built aileron differential ?

Thanks for your reply.

Zor

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

The ailerons will be hinged at the top which will likely induce some diffirential. I will also use the Aileron Differential in my radio to add some more. My 1/5th Scale Cub is hinged the same way and I used the radio programming to get it perfect.

Here is a photo of the 1/5th scale Cub wings with showing the hinging.

SunDevilPilot

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

SDP, did you cronical the 1/5 scale build? I actually chickened out of the Sig 1/4, and bought the 1/5 instead. Just wondering if any mod's are recommended, still following this build with great intrest!

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

SkyPilot101

Not to the extent I did with this build..... The 1/5th Scale Sig Cub is by far the best kit I have ever built. It goes together with ease. I modified the struts into a set of aluminum ones and installed some Robart Cub Gear designed for the 1/5th scale kit. I just got back from flying it. Currently it is my favorite plane I own.

Here is the link to what I did...

http://www.wattflyer.com/forums/showthread.php?t=38812

SunDevilPilot

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

I managed to create the hinge hard points for the wing side of things. The ones on the table are for the other wing. They are all cut from a solid piece of balsa and each should provide plenty of wood for the Robart Hingepoints to glue into. The innermost hard point near the root rib, not visible in photo, had to be built in pieces through the gap in the rear of the wing.

The wing in the photo still needs the trailing edge installed and therefore there is still a gap in between the wings and the surfaces.

My helper gave up on helping!

SunDevilPilot

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

My helper is German! Must be why we are always building Fokkers.

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

SDP, I love this thread. Reading and seeing your progress is truly a highlight to many days. (Geez, what's the rest of my life like eh? Don't tell my wife I said that!)

Anyways, please blame the following wordy explanation on too much schooling and not enough Xbox.

Air passing over the wing can be divided into a couple of groups. The air closest to the wing is called the boundary layer. It is responsible for all of the lift. At the front of the wing, air starts out as “laminar” or smooth, and creates LOTS of lift with very little drag. Gliders try to create wings that maintain that laminar flow over the entire chord. Unfortunately, as the boundary layer passes over the wings, friction slows it down and it begins to tumble and become turbulent. Turbulent air still creates lift! Think of the vortex generators people stick on the upper camber of STOL aircraft. As long as the boundary layer is still against the surface of the wing, it is creating lift. Unfortunately, towards the trailing edge of the wing, the boundary layer has lost a lot of energy and can easily be separated from the wing by the higher pressure under the wing, wrapping around the trailing edge. It is now no longer creating lift and there is only drag.

Flaps create lift in part by increasing the angle of the wings relative chord line to the relative wind. It essentially increases the camber of the wing and increases the angle of incidence. Ie. More lift. Unfortunately, everything described above still happens so most normal plain flaps are not as effective as they could be.

By introducing a flow or relatively high pressure air from below the wing, through a gap, and then over the flaps, it re-introduces energy into the boundary layer airflow and makes the flaps that much more effective. These are called fowler flaps like on most Cessna products or slotted fowler like we see on most airliners. They unfortunately come at a cost of complication, mechanics and weight…none of which you need on a piper cub.

However, by placing the hinge behind the leading edge of the flap, you can effectively create a slotted or fowler flap that moves back and down, creating more lift area, a deeper chord line, as well as creating a gap through which the lower airflow can re-energize the boundary layer. This is essentially the same system deHavilland used on most of its aircraft including the beaver. The down side was the physical hinge hanging in the airstream creating drag, but hey…when you are only flying 90mph anyways, who cares.

This is a great link to some research. http://adg.stanford.edu/aa241/highli...liftintro.html

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

That is some great info Moosehead! Thanks for posting it here.

If I had enough skill I would try to make the flaps shown below. They appear to utilize the physics of what your post explained. Great info!

SunDevilPilot

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

I got the flaps hinged onto the wings this morning. I decided on a hinging method that would give a slight gap between the wing and the flap when deployed. When the flaps are full down there is probably a gap of somewhere between 1/8" to 1/4" between the surface and the wing. To drill the holes I made a guide block that I can clamp onto the wing / flap ensuring a perfect hole. The guide slides onto the wing / flap and is pushed towards the surface until the small stop block hits the leading / trailing edge. Then two clamps go on the little "Wings" of the guide and one goes over the top. I drilled 12 holes in total with this method and all came out perfect.

To align the guide you just make a mark on the flap and a corresponding mark on the wing. Then shine a light down the guide's hole until you can see your mark. Center up the guide on the mark, clamp it down, and drill away.

The guide was made with some scrap maple I had. The hole in the guide was drilled after clamping the guide at the proper angle on my drill press, again, ensures a perfect hole.

I need to make a different guide for the ailerons but the method is the same.

SunDevilPilot

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

Moved right into hinging the ailerons. To drill the holes for the ailerons I made two more drill guides. One had a slight bevel on the bottom to allow the stop block to sit flush with the rear of the wing and still conform to the airfoil shape. The second was undercut a little and went over the taper of the aileron (Which is top hinged). I need to make a trip to the store to purchase a new dremel bit to allow me to carve a slight taper into the hinge hole due to the shape of the hinges at the knuckle. For this project I am using Robart Hinge Points, the larger of which taper slightly larger at the knuckle.

Here is the wing and the aileron drill guides.

Note, the pivot location of the hinge for the flaps is slightly below the wing where the pivot point for the aileron hinge is 1/2 way embedded into the wing. After I cut the tapers I will take a close up photo of each to better document the detail.

SunDevilPilot

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

I used a tiny dremel sanding drum (Handheld without the dremel) and a small file to taper the hinge pockets. The ailerons seat nicely now and there is just the right amount of gap surrounding the knuckle of the hinge to prevent it from binding.

SunDevilPilot

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

The drill guide is a good idea. I will probably see you at the field tomorrow.

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

Sun Devil, you should sell sets of drill jigs. I think they would be popular and I would be at the front of the line. Years ago I got some fowler glue-in hinges from Yellow Aircraft at the Toledo Show for my 1/3 BUSA Super Cub. I can't remember if they were a Yellow product or selling for a buddy vendor.

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

TripleDeucer,

Your hinges have what we usd to see as the Franz Kavan logo on them. Mind you, there is something else to the right of the FK. Could be a knock off, possibly?

They will not give you a fowler flap. A Fowler flap moves rearward as it drops. While there will be a gap between the flap LE and the wing TE, with your Kavan hinges, they will just drop. The Fowler flap, when it is extended, hangs behind and below the wing.

No I'm not imagining this. Check here: http://en.wikipedia.org/wiki/Flap_(aircraft)

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

I guess it was a misuse of words in my post. The FK hinge will work fine for my level of scale as would what SDP is doing with the robart hingepoints. This thread is very useful to me. Thanks

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

Phil, I am reading through the Busa 1/4 Cub instruction manual and a couple things I've noticed already. The connection point for the wing is not nearly as Beefy as the Sig. In my opinion Busa builds a bit on the light side structurally speaking. I'm sure it is adequate. I have not been able to find a Busa 1/4 cub build thread. There are lots of topical posts for this plane, but as of yet I have not found a complete build. Another Busa trait I am seeing is the abscence of a few key pictures in the instruction manual. My Dr1 was like this. Dave at Busa told me that all there new kits have more in depth manuals.
I went over to RCScalebuilder but the site is crashed and will not allow searches right now. All the guys off on holiday overloading the system I assume.
One question I had and you may have covered this, are you putting a scale interior in?
Ron

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

Ron,

The wing attachment method of my plane is completely different from that of the original design. The wing center section, per the stock design, goes with the wings. I modified the kit to allow me to keep the center section of the wing on the plane allowing for the door to be cut out. The interior of the stock sig is accessed through the top of the fuselage upon removal of the wing.

I have seen a Balsa USA 1/4 Cub have a slight mishap / crash and the entire cabin ripped free from the fuselage with little effort. It may be an area that needs a little adjustment.

As for a scale interior I doubt I will be doing much. Because I decided to go electric I will need to be able to install and remove the 10 cell battery. But who knows, the cabin is huge so some seats may be possible. I will definitely be doing a custom dash.

Phil

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

I did a cartwheel with my tank cub and had zero damage, I thought the Fuse would be trashed. I believe a cartwheel with this thing would clean out the cabin. I do try to avoid such manuevers these days. I may beef it up a bit. I will search for some threads that have figured it out for me. I am an oppurtunist when it comes to clever engineering.

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

I had to get the emissions done on my truck this morning and unfortunately the emissions place is right in the middle of the Chandler Municipal Airport. I made a quick stop by the Airport Cafe and took a few photos of some of the planes. This Super Cub flies almost every day and is usually parked right in front of the Cafe, adjacent the Chandler Air Service hangar.

I noticed the safety cables on the landing gear and may have to incorporate that into my plane. I have one experience with some failed 1/4 Cub gear. I was flying a fellow flying field friends's 1/4 Cub and the entire bungee assembly came off one side. Of course the gear came apart and I was stuck flying the plane around with one of the tires dangling under the fuselage. Fortunately I was able to come in with a little slip, initially touch down in the dirt, and get the tire to swing back onto it side. However, because the gear could swing all the way up I still managed to kiss the wing tip as the plane lost flying speed. We flew his plane again, we were going some glider towing, but I really hate hitting my wing tips.

SunDevilPilot

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

Phil, I went back and looked at how you re-inforced the cabin/Window post's. That method makes sense and looks like it would work on the Busa kit as well.
I believe I will clip the wing, and put two wing tubes in the center section for added strength and ease of assembly. I may need to create a couple of extra center section plywood root ribs.
Ron

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

http://www.riversiderc.com/album_062...20cub%201.html

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

Nice Photos AmishWarlord....

Not much to report. I ordered the streamline aluminum for the struts which will be my next project in the build. I am also looking into how I will mount the servos in the wings. Most likely I will install them like I did in my 1/5th Scale Cub, servos mounted to aluminum brackets which are bolted to plywood plates. Here is an example of my install on the 1/5th Cub. I already have two of the aluminum mounts made and a second set could easily be fabricated. The mounts are cut from 1" extruded aluminum.

SunDevilPilot

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

Phil, I pulled my H9 1/4 Cub off the wall last night and I am going to put the DLE 30 in it. I decided to break the engine in on the Cub instead of the Tripe. I should get some more flying days in that way consdering crosswinds. I am not sure how much cowling will be left. I thought I would check and see if the BUSA cowl would fit, but it is much larger. Funny how different all these 1/4 cubs are in dimension. Anyway I thought I would warn you that I will probably be asking yo you adjust a new Carb soon;)

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

Sounds good!

The DLE30 should make the Cub a little more lively.

Phil