I'd like to share my process building my scratch built Cub with this group, as I have mentioned in a recent previous post in "New Member Introductions".
Myself and a building partner friend of mine are each building scratch built Cubs together. My intentions are to share my progress, learn from the group, have good discussion, all while I work toward a completion.
John
Thank you for sharing and welcome. Glad to have your thread.
Bill
Very Blessed.
Builder's Update: I thought I'd share a fixture I made to align the torque tube masts which I built (thanks Christian Sturm showing how to make the mast on his web site). I used a piece of 1-1/4" thick material, shaped it as shown, and drilled 2 holes at the appropriate distance apart to position the masts. I fixtured the parts up, clamped in place, then my building partner did the welding.
Having seen no more of your project than what you've posted, I have no doubt that, if you stay with it, you will build a "high-craftmanship" airplane. Apparently you've built airplanes before.
Great idea! Look forward to updates.
Lunch Time Aviation presents a builder's update: It's lunch time, so I thought I'd take a little time to provide my project update. Continuing with the Torque Tube assemblies, I have attached photos of the torque tube bearing mounts. I typically draw any flat steel parts on paper, then glue (spray adhesive) the paper template to the sheet, than cut out the part. Here I used a portable hydraulic punch I borrowed from work. I got lucky that the large hole I needed to punch was the same diameter as one of the punch and die sets we had. Electricians use these punches to punch holes in electrical panels. After punching, and cutting the part out using a cut off wheel or a sheet metal shear if applicable, we bent up the flanges, and assembled. In order to cut out the curved lines to fit to the bearing tube, I drilled a series of small holes just outside the line, then wiggled the scrap part away from the good part, followed by using the bench top grinder to smooth out the steel to the shape of the curved line. We fixture up the parts welded. My project partner has been doing the welding while I typically fabricate many of the parts and the fixtures. It works out well for us. We're building two cubs, so our combined interests works out well for both of us.
http://www.supercub.org/forum/showth...ighlight=larry Larry here is about the best if not the best jig maker ive seen here. his website is listed at the bottom of his posts. Sortve wondering how his project is going??
Thank you Tempdoug that is a very nice thing to say.Originally Posted by tempdoug
Larry Experimental Supercub PA18 wide body
http://www.mykitlog.com/Supercub
I'm positive there is no life on other planets - if there where, America would be sending them financial aid
Lunch Time Aviation presents a builder's update - My building partner (Charlie) and I (John) now have the majority of the tail feathers, fuselages on landing gear and much of the torque tubes made. All scratch built. Today, I want to share progress of my front seat. We decided to build non-adjustable front seats. I modeled my front seat, seen in the photos, to the same dimensions as a PA-18 seat, when the seat is in the most rearward position. I will not have any brake pedals for the rear passenger, so the rear legs on the front seat can be straight up and down, and land on existing cross members. I designed and made the fixtures, and that's Charlie welding the seat parts up in the photo. My intention is to lighten up the seat a little, and sacrifice passenger brake pedals for weight savings. I hope to install toe brakes for the pilot only similar in design to those I use on the Rans Courier I fly, and like just fine.
Good to see you on the forum John! Lots of good info here. You'll enjoy I'm sure.
Joe
Fortis Fortuna Adiuvat
I'd encourage you to do the Atlee style folding seat mod on your front seat. Also add about 7-10 degrees of recline to the seat. You will be glad you did! Nobody sits at 90* angle! The seat bracket templates are on my web site.
https://www.aircraftspruce.com/pages...on/booster.php And an idea for the rear seat, with these cushions and Bill Rusks, building a Javron cub, rear seat way, post number #528 easily removeable. But in the end do what you guys want thats what makes it cool, but dont mind if some ideas are thrown in along the course.
Last edited by tempdoug; 02-02-2016 at 04:49 PM.
Thanks for the thought Bugs, I've seen that seat, and I'll take a look at the drawing. The seat back is actually leaning back a few degrees, and I struggled a little on leaning it back as far as I did, as I tend to lean forward when I drive and fly... I mocked up a wooden seat and placed it in the fuselage prior to welding this one up. To my surprise, the seat was really easy to fabricate, after a fixture was created, so any changes will not be a heart ache.
Thanks all for your support from all the folks. I appreciate it, and it helps. I have a list of questions to run past folks when the right he time is right.
john
In addition to what bugs said consider egress from the rear seat. Without a folding seat back and the seat located further aft rear seat entry is restricted.
Everybody has different needs. I have a couple thousand hrs in the back seat of J3s, Pa11 and my Ex 18 all with solid front seat backs and don't see it as a problem. Stay flexible.
Glenn
"Optimism is going after Moby Dick in a rowboat and taking the tartar sauce with you!"
Not everybody you give rides to is as flexible and cool as you.
Thank you, But the 275lb farmer thought it was cool being back there also, he didn't fit in the front so we switched. Never had a folding front seat but probably like it if I had one. Just thinking the rigid one is better protection when things come to a sudden stop?
Glenn
"Optimism is going after Moby Dick in a rowboat and taking the tartar sauce with you!"
Posting some photos of my landing gear fabrication:
I hope these photos may help a person down the road, and I appreciate the positive feed back and suggestions I received from this group. Thanks, john
WanaBNACub liked this post
John,
Really Nice looking craftsmanship, it was nice talking to you at the EAA Ski Plane Fly in, good luck with your build, im sure many will be looking on with interest as you proceed to the outcome, I'm looking forward to seeing the end result!
Rick
As I am preparing to mount the tail surfaces (we scratch built) to the fuselage, I thought I'd share how I made a tube bending fixture to bend the leading edge spar of the stabilizers.
We first tried to bend the tube around a flat surface, and the tube kinked. I then researched, and found a tube bending fixture from the Tony Bingelis book series that EAA sells.
Here's the fixture I made and the bending procedure:
The fixture has different bend radius's on it to create different bend angles in the tube.
I used a 1-1/4" thick piece of counter top material, and routered the edge all around.
The routered edge closely matches the tube diameter that we need to bend.
A steel "wrap around hold down clamp" is needed to retain the tube firmly against the fixture. Here, a person can decide which part of the fixture to bend the tube on.
I inserted a spring to guarantee the tube doesn't kink again. This worked so well, I never tried bending the leading edge stabilizer spar without the spring in place.
The spring is about 9" long or so.
Slide in the tube and start bending (downward pressure). It's a good idea to draw a line (lengthwise) along the top of the tube, to use as a reference,
in the event a person needs to remove the tube from the fixture, test fit it, then stick it back into the fixture to bend it a little more.
Remove the spring when finished.
Fit the tube into the stabilizer fixture.
All the sheet metal ribs were fabricated by cutting the steel on a shear, then bending the steel to the required shape using a sheet metal break.
Then back into the fixture for final fit up and welding.
Similar procedures were used to fabricate the remaining tail surfaces, however the bending fixture was not needed when bending the smaller diameter tubes.
I hope this helps a person work through this part of the build.
john
Nicely done! Great info. Keep them coming
Lunch Time Aviation presents - Fuselage Construction.
I should include some documentation of the fuselage construction for folks. We started by drawing the layout of the sides of the fuselage directly onto our flat work bench.
We used a hand held conduit bender to bend the longerons to shape, then pieced the tubes in place. Everything was hand fitted. We used a bench top grinder to notch the tubes.
We're building 2 planes, so by the time we got to the fourth assembly, we blasted through it very quickly.
With matched sets of "sides", we drew a center line on the table and set the sides in place.
Plum bobs, framing squares, wood blocking, and diagonal cross wires with turn buckles provided the needed method to square up the fuselage to add the cross members.
Keep an eye on the plum bobs and adjust the fixtures to keep things correct.
I built this boxed fixture to maintain the correct longeron angles and to set the tail post in place for fitting and welding.
The boxed fixtures are screwed to the work bench to ensure things stay in place.
Here's the Tail Post Fixture removed after tack welding. This worked very well.
Looks pretty good so far.
The fuselage.
Then we moved the fuselages to another shop where my build partner, Charlie TIG welded things up.
END.
Rudder Fabrication - If a person wants to build a rudder and does not have a rudder to copy the shape of,
here's a pretty simple way to draw a smooth curve to make the rudder look correct.
Refer to the Rudder print to get the coordinate's of the rudders' curve and required dimensions (if you want it to match to the plans).
Layout the coordinates and other required dimensions onto your work surface.
Rip of long continuous piece of wood banding from a length of soft lumber (pine?).
Attach some blocks to the work surface to locate the rudder post and used to clamp the banding in place.
Lay the banding on edge, making sure the banding intersects the required coordinates.
Clamp the banding to the wood blocks at these coordinates or other locations in order to get the banding to intersect at the correct coordinate locations.
The nature of the wood banding creates a nice smooth curve as it intersects the coordinate points.
Only light clamping pressure is needed on the banding to maintain the smooth curve. Too much clamping will distort the curve.
Trace the shape of the curve onto the work surface, then remove the banding.
Bend and fit the rudder tubing to match the profile drawn on the work surface.
Sheet metal ribs can be fabricated using a sheet metal shear and break to form the ribs.
Weld it up. Then on to the Vertical Stabilizer. It may be wise to use the rudder as a guide to ensure you end up
with a nice transition at the leading edges of the vertical stabilizer and rudder.
I'm sure there are other good ways to form a rudder, and I hope this helps a person if they elect to scratch build.
john
Very very nice John. I hope you're keeping all those jigs for your next build. I particularly liked the camming circle in the vice to get your curves right for the stabs leading edges. I did mine with a tube roller and that worked well too. Love to see these scratch built cubs..... Looks like you're making good time too.
"There are three things in life that people like to stare at: a flowing stream, a crackling fire and a Zamboni clearing the ice." Charlie Brown
Please Join and Support the RAF! http://www.theraf.org/
I'd like to share work completed on various scratch built ribs. I made the three samples shown in the photo, and I like each sample for different reasons.
The rib in the bottom of the photo represents a "one-piece-sheet metal rib". The rib blank was sandwiched between two wood shapes,
then the flanges hammered using a plastic mallet. I then used fluting pliers to shrink the flanges where needed. The lightening holes
would be punched and flared using a "Mittner Punch". I only have access to a 4" diameter Mittner punch, so the lightening holes would be a little small.
Stiffening beads can be added using a bead tool, however the bead on the rib was made by hand. The rib material is 0.020" 6061T6 aluminum.
11.04 ounce (3/4 rib) before holes are punched.
The rib in the center of the photo is a "three-piece-stamped rib". Here, I made forms (nose, center, long tip, short tip) to router out the rib blanks, then form the
rib using a hydraulic press (hydroforming) using similar dies. I made all the forms and dies by hand. The rib shown requires the ribs to attach on the web of the spar,
however, the ribs can be attached to the top and bottom flanges of the spars, with similar forms and dies. The rib material is 0.020" 6061T6 aluminum. 11.62 ounce (full rib).
The trussed rib at the top of the photo is made of Carlson cap strips, and 0.020" 6061T6 aluminum. I have since made another using 0.016" aluminum (I like it). I included stiffening beads,
and later I added lightening holes all over. 12.32 ounce (full rib). Very, very strong rib. I've seen similar rib come in lighter than this one. I also bent up a piece of 6063T52 aluminum angle,
1/16" thick, 1/2" x 1/2", and like it as well. I like the trussed rib a lot simply due to being able to use very simple tools to make it. A person can almost make these in their living room.
I made two forms for the trussed rib, one form to pre-bend the cap strip, and a second form to maintain final shape during assembly.
My build partner Charlie was able to buy some beat up stock Piper ribs, and one of the FULL ribs I weighed came in under 7 ounces! I checked my scale calibration,
and feel confident that that is a good weigh. The Piper cap strip is so light and flimsy, that I feel any of the ribs I made are "over built".
More to come as I learn.
john
Project Update - Upper Cabin Structure in Process
We're back to building after a break for EAA Airventure and New Holstein. Had a great time at both, and enjoyed meeting some folks.
The Throttle Brackets were fabricated and tack welded in place. I used a straight pine board
to align and plumb the brackets.
I then fixture up the Upper Cabin Structure Roof using an assembly of wood, wire and turnbuckles.
The X-Roof weldment sets on a sheet of medium density fiber board (MDF) with wood cleats holding it squarely on the board.
A second sheet of MFD sets on the upper longerons, with pine boards clamped in place to position the roof per the plans.
I'm using the stock roof angle, so the front edge of the roof is 24-3/4" above the upper longeron ,
and rear edge of the roof is 22-1/4" above the upper longerons. Angle of incidence can still be adjusted using wing attachment fittings if desired.
The entire assembly is held taught using diagonal brace wires, with turnbuckles to adjust the tension, and to square up the structure.
Plumb bobs, levels and tape measures are used all around to check alignment.
The cabin cabanes were then cut, fit, and tack welded in place.
Before final welding, we thought we'd better make sure we can get the fuselage out of the basement work shop.
That's Charlie up there, relieved to know that we are good to go.
Thank you, john
Looking good John and Charlie!!! Keep up the great work.
Joe
Fortis Fortuna Adiuvat
A Builders' Update - Fabricating and installing motor mount spools, and the diagonal tubes under the wind shield.
A sheet of flat plywood was used to ensure the motor mount spools all lie on the same plane.
A flat sheet of medium density fiber board was used to create the fixture required to lay up the diagonal tubes.
Tube lines and intersection lines were drawn to locate the tubes.
With tubes in place, the tips can be cut off to create a butt joint weld at the intersections of the tubes.
Tack weld the tubes while the fixture is in place.
Remove the fixture, and finish weld. I still need to add the short tube running from the intersection
of the tubes down to the fuselage cross braces tubes for additional stiffening.
Recent Fly Out Photos - My wife, Mollee and I flew to near by Wausau, Wisconsin to see the leaves.
The good people at the FBO offered us to take the bicycles to town for lunch.
So we did.
Thank you all for your good comments regarding our two projects.
John
Speaking of bicycles.....getting a folding ebike (Montague) in the back of a Cub without a folding front seat back seems to be about impossible. At least it appeared that way to me at JC this year, when I was checking out the XCub while Jim Richmond took my bike for a spin. My thought at the time was IF that front seat folded forward like the RANS does, at least the seat back, it would have fit. As you have an S-7 I'll be curious to see if your scratch Cub build has anything from that design, like a larger door for one. I've shamelessly stole many Cub mods and ideas for my own S-7!
Nice build, great explanations of what and how your doing things, educational but entertaining also.
Very impressive. i am totally in awe and envious of people with the skills, tenacity and time to take on a project like this.
i'll be following this thread and learning all i can.
cheers,
Phil
Cub Building Update - Lower Door
I now have most of my lower door figured out and built. I decided to build a simple door using 1/2"x0.035" tubing for the perimeter of the door, instead of the formed sheet metal pieces as on a stock Cub, and I used 1/4" tubing for the two braces or stiffeners inside the door. The two hinges are the stock style metal piano hinge made out of 0.040" thick steel, which I bought from McMaster-Carr, then I cut them to length. The latch mechanism design is swiped from the Rans Courier I fly which has a simple pivoting handle, similar to a cub throttle lever, with 3/16" diameter tubing (McMaster-Carr) linkages running horizontally across the door and against the interior of the fuselage to hold the door closed.
I outlined the door opening on a sheet of thin plywood.
I cut and fit the tubes, leaving the desired gap between the door and the fuselage. The tubes were tack welded while on the fixture.
I then made sure the door fit properly in the fuselage, and added the brace tubing. I positioned the smaller tubes flush to the outside surfaces of the larger tubes.
I positioned the hinges as shown, using pieces of sheet metal to ensure the hinges were aligned to the door. The sheet metal pieces also position the outside of the door, to the outside of the fuselage. I ended up taping the hinge to the door using electrical tape to hold the hinge in place so the assembly could be removed to weld the hinge to the door.
Realizing that the two halves of the hinge will be sandwiched (closed), I cut the top half of the hinge a little longer than the lower half of the hinge, so we could tack weld the top half of the hinge to the door, without the lower half of the hinge being in the way, while the hinge was taped accurately in place. Later on the lower half of the hinge can be welded to the fuselage.
I drew the latch design and taped the drawing to the door to get a good idea of size and location.
I made the assembly as shown and we welded it in place on the door.
Similar to the Rans Courier door latch, I fabricated a tab with a 10-32 threaded stud welded to it. The tab and stud are welded to the door. I then fabricated a "T" shape assembly consisting of a piece of tubing for the door linkage to pass through, and a small threaded coupling style thing welded together in the shape of a "T". The "T" fitting gets threaded onto the stud. The "T" fitting has the opportunity to rotate a little to follow the slight rocking path of the door linkage when in operation, and it has the opportunity to be adjusted "in and out" to have the right amount of space or interference between the sliding linkage and the mating fuselage tube when closing the door. This type of assembly was fabricated for the front and rear ends of the door. You will notice that there is a positive "stop" welded to the fuselage, for the door to bump up against.
Here is the door in the closed position. I intend to add a threaded stud to the rear linkage, for a knob to be attached, so the person in the back seat has the opportunity to easily open the door.
I intend to add a little retainer guide on the upper door tube, along the door handle similar the retainer guides used at the throttle levers on stock Cubs.
Thank you for viewing.
John
Great project. Real nice craftsmanship. I Designed and built a cub clone a dozen years ago. Drew my own plans and built every part except windshield and nose bowl. Banged out all wing, flap and aileron ribs. Used Carlson wing spars and lift struts. Fuselage built like carbon cub way before the carbon cub. Bought inexpensive O-235. I didn't build as nice of jigs as you. Spent 15K. Took 10 years.
I see a Waco cabin biplane model hanging from a ceiling. Think I'll build one of those next.
Very nice project and well done so far!!!
Building Update - Torque Tube Installation
The following is additional detail on torque tube construction and installation onto the fuselage.
Bend the torque tube masts using a form as shown. I appreciate Christian Sturm sharing
this method on his SupercubProject web site which I followed.
I drew the mast for paper templates to cut the mast to shape.
I find it handy to include a lot of information on the drawing such as
the type and thickness of the material to use, the orientation of the grain
of the steel, and the drawing number. This helps reduce error when
fabricating the parts.
Clamp the mast as shown in a vise, then heat and bend the
ears on the mast to create nice bends.
Fit and weld the masts onto the torque tube. Use a board attached to
each mast to maintain alignment. Don't forget to add the bearing collars
onto the torque tube prior to welding the masts in place.
The control sticks are made to plans. A paper template was cut and
and taped as shown to get the correct shape of the lower end of the
control sticks.
The lower piece of the control stick was fabricated and drilled.
Carefully align the holes in the mast when drilling, and add bushing stock.
The bushings can be trimmed (sanded) to a final length later.
Use the assembled torque tube as the fixture to position the torque tube
mounting brackets onto the fuselage. Clamp the torque tube onto the mounts
using the bearings fabricated. When welding the torque tube mounts onto the
fuselage, tack weld the mounts in various spots before applying a lot of heat
in one area to prevent the assembly from pulling due to heat. My building
partner, Charlie is doing the welding here.
Thank you for watching.
A PROJECT UPDATE
Elevator Cable Pulley Brackets,
Baggage Compartment Tray,
Throttle Control and Mounting Brackets,
Front Seat.
The front pulley bracket has been fabricated and installed. Notice that
the retainers that prevent the cable from falling off are held in place
by the small shoulders on the bracket.
Cables were mocked up to properly position the elevator cable
pulleys under the baggage compartment. Notice the baggage
compartment tray is mocked up at this time as well.
The sheet metal supports for the baggage compartment
are welded in place, resting on the rear seat cross member.
I added a short bend on the support to stiffen it. The short
bend on the bottom stiffens the support considerably.
The rear seat belt attachment bracket is also seen here.
I draw many of the parts, and glue the print onto the steel as a template.
This is one of two throttle mounting brackets. Holes are drilled first,
then saw cut to the holes and sand along the edges.
The parts were bent up, drilled, and bolted into place.
Here's a photo of the front seat in the fixture to weld up the legs.
Notice that the rear legs are straight up and down, and are not to plans.
A photo of the front seat almost finished. The seat is welded up to match
the rear most position if the seat were adjustable.
I want to easily remove the seat, so I have short pieces of tubes (sleeves)
welded straight up from the fuselage. Having all four legs running parallel
offers the opportunity to slide the seat legs easily onto the sleeves.
Pins or bolts will secure the seat legs onto the sleeves.
Coming along nicely.
Can't wait for summer to go flying with my wife here in Wisconsin!
Thanks for watching.
john
Lookin' good John!!
Full scale or model? I used to own the last Waco cabin built a VKS-7F. It is a very nice flying comfortable airplane and reasonably fast.
N1PA
Project Update - Tail Wheel
The following are photos of my tail wheel section fabrication. Being a light cub, I am going with a two-leaf spring (I think).
I bought the spring (1000 lb. capacity) online, but since then, I found the same spring for sale at my local "Northern Tool"
store (formally "Northern Hydraulics"). The spring cost me $20. It's wider than usual at 1-3/4".
The spring is a trailer spring, used on light duty trailers.
The spring.
When drilling a hole in a leaf spring, use a slow drill speed of about 60 rpm. A machinist friend also mentioned
to me that a flatter cutting tip angle on the drill bit works good when drilling harder steels.
The spring can be cut to length using an abrasive cut off wheel in a right angle grinder.
Use the scrap piece to form the attachment bracket.
Using the scrap spring end to form the bracket. Use Oxy-Acetylene torch to heat to bend.
More bending.
The final shape.
Cut and bend the attachment bracket that gets welded to the fuselage.
The finished bracket.
Fit and weld.
Drill holes and bolt it on. The spring length can be changed as needed, to adjust the caster angle and stiffness.
I'll likely start with the solid tail wheel, in the assembly shown.
Thanks all,
john
Looking good John! Nice work.
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