John's One Design

Power Wiring

JP — Sun, 31 Mar 2013 04:01:40 GMT

The power wiring for the instrument panel has been done. A fuse panel has been added just below the instrument panel and centered.

An hour meter was added. The FAA requires 40 hours on the engine and prop before a permanent airworthiness certificate can be issued. Both are experimental. If they were certified the time would be 25 hours. It will probably take me all of 40 hours and more to get the plane setup.

The fuse panel has a yellow chromate finish so I won't have to paint it right away.

The power to the radio, transponder, glass panel, boost pump, smoke pump, fuses and switches have been installed. Over 200 feet of wire was needed for this. The voltage regulator for the alternator is mounted on a separate panel on the right side of the fuselage frame. The panel is held in place with adel clamps.

All of the ground wires are connected to a copper ground bus. The ground bus is silver brazed to the fuselage frame. It is located on the right side beside the radio.

The instrument panel back side is shown. There is an alternator disconnect relay and over-voltage module just above the switches.

The wiring is laced in place in accordance to NASA-STD-8739.4 This is much more reliable than the plastic cable ties. The headphone jacks are installed in the cockpit on the right side. There is shielded wiring going from the headphone jacks to the radio mounting chassis.

The thermocouples and wiring for the transducers for the engine monitoring will most likely come from the engine compartment on the left side. This is the side where the Dynon D-180 is located.

Mounting the fuel tanks

JP — Thu, 21 Mar 2013 04:07:32 GMT

Some time ago I mentioned someone having a Pitts whose fuel tank mounting bushings tore out of the longerons. After hearing this I decided to mount the fuel tanks a little different. The One Design appears to have the same mounting scheme as the Pitts.

I used 1" stainless steel straps with rubber around them. The fuel tanks are electrically grounded with a pair of wires attached to each tank. The ground tabs were shown in the previous post.

I made mounting brackets which wraps around the outside of the longerons. Here are the rear brackets, they are made from 4130 strap 0.10" thick.

The mounting bushings that are welded into the longerons hold the mounting brackets in place but did not support the total weight of the fuel tanks. In fact they support very little weight. The bushings do however, hold the tanks from sliding forward and backward.

Additional fuel tank supports were added under the lower tank. These support the weight of the tanks primarily in upright and inverted attitudes.

Here is how the straps attach to them.

The mounting straps have an L shape piece riveted to the ends. The straps for the lower tank are riveted to the bottom strap of the upper tank. It makes an H shape.

The upper tank has a fuel fill dam spot welded around the fuel cap. Proseal will be used to seal the bottom edgesand the drain tubes entry point. A pair of aluminum drain tubes will allow any spillover to drain to the ground and not into the cockpit. The top of the upper tank is a little over an inch below the outside skin.

Just behind the fuel fill dam is the top of the capacitance fuel level gauge.

Fuel Tanks

JP — Mon, 14 Jan 2013 03:23:04 GMT

I finally got around to welding up the fuel tanks. I wasn't completely satisfied with the way the ends of the upper tanks came out. While forming them over the form it was a challenge shrinking the metal without folding it over itself and producing cracks in the edge. When I finally made a couple of tank ends the that didn't crack the center was concave. I would have had oil canning in the tank ends by using them and flying acro. So I built an English wheel and domed the metal before turning the edge over.

I made a form out of an oak stair and routed a radius along the edge. I then began hammering the metal over the form. I used a Lancaster shrinker to pull the metal in along the edges. I found that by starting the shrinking at the most radius area first produced the best results. This would be the sides of the upper tank. The shrinker leaves bite marks in the metal but they can be buffed out with a scotch brite disc prior to welding.

The lower tanks had very tight radius corners, about 1.5 inches. The shrinker is good down to about a 3 inch radius. It wouldn't work for the lower tank. For the lower tank ends I cut and welded the corners. They were welded both inside and out. I did crown the pieces first on the English wheel just as I did for the top tank ends.

The lower right is a tank end, domed slightly and ready to be folded and welded. The lower left is a finished lower tank end.

The sides of the tanks have a dual bead around them. The beading is done after the sides are bent to the shape of the tank. I plan on using stainless steel straps placed inside of a rubber barrier rather than using the aluminum strap that is called out in the prints. The bead will also give a barrier to any stress from the welded seam. The tank should not deform from welding the tank together, and it didn't. Any pulling on the bead area was not noticeable.

The stainless steel straps will be placed between the beads. When I welded in the fuel tank cap I failed to add a bead around it. There is a slight deformation on the top of the tank from welding in the fuel cap. That proves that the bead helps by giving the weld a shape to pull on rather than pulling on the flat and causing deformation.

I also added a pair of tabs to each tank so ground wires can be added to each fuel tank. Two wires on each tank should eliminate static problems just in case one gets broken off.

Additional stuff

JP — Tue, 31 Jan 2012 00:25:26 GMT

Now I am into the final stages of this build, all the miscellaneous stuff that was overlooked in the beginning.

Here is the instrument panel with the Dynon D-180 and the Garmin GPS. I will most likely update the GPS to the Aera model this summer. The new GPS mount fits the same panel hole so it will be a simple swap.

I made the switch guards out of Aluminum. They were made to match the switches and have a 1.618 aspect ratio. I had to make a bending tool to fabricate them. The switches are sealed toggle switches with silver contacts. The manufacturer is APEM and they are sold by Digi-Key. They are pricey but they will be reliable for the long term. The labeling was done with clear Avery labels and a laser printer.

The Icom IC-A210 radio is on the right panel and the Garmin GTX 327 digital transponder is on the left. The transponder will interface directly to the Dynon D-180 for the altitude. The copper ground strap is brazed to the fuselage frame near the rear of the radio.

The Christen oil valve is mounted on a 15 degree bracket. This bracket is mounted to steel angle welded to the fuselage frame. They contain anchor nuts and the bolts will be drilled head AN4. The valve is too heavy to mount only to the stainless firewall.

The 15 degree mounting bracket will insure positive operation of the oil valve on a vertical upline and reduce the chances of the propeller surging.

I went to a metal shaping seminar at Fay Butler's shop. We are using a radius gauge to locate the highlight lines. These are the borders for the shrinking and stretching operations. As a result of locating and marking the highlight lines you can fabricate metal panels with a minimum number of welded pieces. I should be able to fabricate the two nose bowl pieces without welded seams.

I am shrinking the outside of the panel for the lower engine cowling on a Pullmax machine using thumbnail shrinking dies.

This picture shows me stretching an area of the nose bowl using John Glover's English wheel.

New Paint

JP — Sat, 03 Dec 2011 01:31:52 GMT

The large pieces are painted. Here is the wing assembly top side.

There is geometric distortion in this picture due to limited space and the required camera angle. The lighting is the florescent twisty bulbs so the color is off as well. The colors are Insignia White, Miami Blue and Platinum Gray.

The bottom of the wing is alternating white and blue longitudinal stripes (front to back) each 15 inches wide. The distortion is displayed very bad on that picture so it won't be included here. It would be too misleading.

I put the N number on the vertical stabilizer and the serial number plate on the fuselage aft section. The belly is painted blue. This is so it won't show smoke oil residue as bad as a light color would. That is what I have been told.

The checkered stripe is supposed to match the wings. The angle of the pattern is different on the stripe. It will match up to the cowling opening. The the ratio of pattern length to stripe width is 1.618. The check pattern on the wings is also 1.618. I guess I will see how it looks when the plane is fully assembled.

The landing gear is also painted blue. I expect that this will be less maintenance than if it were polished.

2000 hours

JP — Sun, 30 Oct 2011 00:44:25 GMT

I made it to the 2000 hour point, 2040 to be exact, but the plane isn't finished. Some 200 odd hours over the past 3 months have involved stripping the fabric off of the fuselage and empennage and replacing it as well as priming and painting it a second time. Not something I wanted to do. I suppose that is what I get for listening to a friend's recommendation.

Applying the fabric and fabric tape is different with the Poly Fiber and Stewart's system. Both systems are relatively easy for that part of the covering process. Painting is easier with Ranthane than with Stewart’s water-borne paint. The viscosity of Ranthane paint is consistant whereas with the water-borne paint the viscosity is different with each can. You need to use a viscosity cup each time you mix the water-borne polyurethane for spraying. With Stewarts paint they recommend that each coat should be progressively thicker and that you may need up to 5 coats on fabric. With the Ranthane paint it is much easier to apply, only 3 coats. The pot life of the water-borne polyurethane is about one hour. The pot life of the Ranthane is 4 to 5 hours so you are not rushed. After using both I prefer the Poly Fiber system with Ranthane top coat over Stewart’s products.

Both top coat paints are catalyzed polyurethanes so a fresh air respirator is required when you spray them. Stewarts claims you can use a charcoal respirator like the ones used for organic solvents but I don't trust that statement in the least. Poly-isocyanides are components of the catalyst and a charcoal respirator doesn't stop them from entering your lungs. You can get a fresh air respirator for under $500 and that is a lot cheaper than a lung transplant. With the Tyvek coveralls and hood with air blowing inside you end up looking a little like the Michelin man. Sorry, no pictures. The blowing air also keeps you cool, Tyvek is an air barrier and does not breath.

The one thing that still annoys me is the fact that when you have wet paint on a finished surface, it seems that is when every bug within a 10 mile radius has to arrive and land on it. It is a little annoying to have to walk around with tweezers and remove bug carcasses from the wet paint and then sand down their remains before applying the next coat. This is somewhat tolerable with the primers but not so much so with wet top coat. Maybe I should hire Kermit the Frog to stand guard over the wet paint.

Here is the side of the fuselage, fabric only. Still have some trim colors to do.

When masking the elevators and rudder I tied lacing cord on each side of the strap hinges so the paint doesn't get inside of them and cause them to bind. No closeup available.

With the hinges on the trim tabs I threaded masons twine in where the hinge pin goes to block paint entry.

Now I can put the tail wheel and landing on and then attach the motor.

Fabric Recovering

JP — Sat, 03 Sep 2011 18:27:13 GMT

I painted the fabric the end of June. The first time I painted the wing it came out looking good so I expected the same results on the fuselage. That was not what happend.

On one area of the fuselage the surface finish of the paint looked odd. There was a chalky watery run from the edge of the paint onto an unpainted area. I sanded the paint down as much as possible and applied fresh white paint over the area. It appeared better but not the same as the first time I used the waterborne paint.

I applied fine line tape and shot the blue paint to the bottom of the fuselage, the elevators and landing gear. The fine line tape lifted sometime during spraying of the blue paint. I have not had this problem with the tape on any other surface. The blue paint went on normally but the color seemed to separate after 10 minutes on the elevators and landing gear. On the horizontal stabilizer the white paint didn't appear to fully catalyze, it remained slightly sticky on the surface even after a month. This was the same paint that looked odd on the fuselage.

I contacted Stewart Systems and told them of the problem. They sent me all sorts of information about setting up a HVLP gun and setting up a paint area, using 3/8 hose, etc. I have the setup recommended. I removed the fabric, cut pieces and sent them to Stewart and then called. Again more talk of the HVLP gun setup and technique. I asked them point blank what caused the sticky surface and uneven color. They said they didn't know but even with catalyst at 6:1 it should fully catalyze. I havn't heard anything from them since.

The paint is supposed to have a 1 year shelf life, the white paint was well within that time and the blue was purchased recently. My guess is that the paint sat in a warehouse somewhere much too long. A friend, who happens to be an automotive painter concurs with my opinion as to what the problem was. He mentioned that pigment colors also have a shelf life.

The PolyFiber and Ranthane paints have a 4 year shelf life and 5 hour pot life so they should be much easier to work with.

On an upbeat note. Someone has mentioned ball bearings can be added on the idlers in the linkage going to the elevator. That is something that I think is a good idea. Now that I have the fabric off it is easy to weld in new brackets to mount a modified rear idler.

The rear idler can be cut and a piece of 1 inch tubing can be welded to the base to house a pair of KP-4 bearings. If the fabric was still on I would make up new brackets on top of small square tubing and bolt the assembly to the brackets for the original idler and add adel clamps to the other end.

For the front idler it is just a matter of fabricating a new one. The bearing locations will be the same as on the original idler. The spacing between the sides of the front idler should be increased to 1/2 inch. Just a little bigger than what is called for in the plans. The increased size will allow the use of the Aurora rod end bearings with the larger useful angle than the Heim bearings. The Heim bearings have a angle of 10 degrees. The angle of the front rod in the elevator linkage can go further than 10 degrees if the stick goes to the stops. Someone mentioned the angle issue on the 1D users group a while back and recommended a change to the Aurora rod end bearings for the front link.

A KP-4 bearing can be held in place within a piece of 1 inch tubing (.901 ID) tack welded in place The bearing is held between the weldment and a floating side with AN3 bolts. The floating side is also bolted to the main idler weldment with screws and anchor nuts. The thru-holes on the weldment and side plate should be more than 1/2 inch diameter to clear the inner bearing race. There is a piece of 1.5 inch tubing around the outer edge to dress things up. The tubing pieces are .3 inch long which is slightly less than the thickness of the KP-4 bearing outer race.

The idler will mount with a single AN4 bolt and be located with 3/8 inch OD pieces of tubing.

The rear idler was cut and now has a 4 inch piece of 1 inch tubing added to attach to a pair of KP-4 bearings. Each of the bearings will have a separate bolt, hence the pair of cutouts to install the bolts and attach a wrench. The previous mounting brackets have been ground away and a pair of brackets are welded to the fuselage cross piece for this idler.

Add a little paint and the new idlers can be installed.

Aluminum Nose

JP — Fri, 10 Jun 2011 11:14:02 GMT

I have decided to build the nose of the One Design out of aluminum, or should I say use the building of the One Design as an excuse to learn to form compound shapes in sheet metal. There is a local coach builder in my area who gives weekend classes on shaping sheet metal. I decided to go and learn what I could. I picked up a lot of information and was able to begin the aluminum nose.

The first thing I needed was the size of a nose bowl. I used a one piece fiberglass MC3A and cast a profile of the perimeter of the nose using plywood and bondo.

The next thing I had to do was design a nose that I liked. The MC3A, in my humble opinion would look like crap on a One Design. The aluminum nose will be a 2 piece assembly. I attempted to make a design in CAD with help from from some experts at work. This was partially successful but I ran short of time before completing it. I had to make a buck before the sheet metal class and was running out of time. I cut sections in the CAD model, printed them 1:1 and glued them to plywood and cut out the shape. The bottom came out ok but I wasn't satisfied with the shape of the top. There is a reverse curve that blends to zero which I was not satisfied with. At this point I had to wing it.

You can see that the bottom buck construction allows for clamping of the sheet metal. That is not the case on the top buck, in simple terms I did not finish the top. It did serve a purpose. It gave me the perimeter and the height and outline of the opening.

The next step was to develop a shape that I would be satisfied with on the top. For this task I used 0.025" soft aluminum and shaped it a section at a time and welded the pieces together. Welding this stuff was a real PIA even with a piece of copper strip as a thermal backing. It also distorted like crazy but I was shown how to fix the distortion. I put the reverse curve in and pulled out one end of it. I also shifted the location of part of the curve. I did this more than once and generated a shape that I can live with. It is surprising how easy metal can be made to move, sometimes where you don't want it to go.

Rather than polishing the metal surface after welding the pieces together I added a skim coat of bondo and sanded it smooth. This now became the master shape for the top.

Now that I have a shape for the top of the nose that I can live with it was time to make a flexible pattern. I used paper tape and fiberglass strapping tape to make the flexible pattern. The flexible pattern defines the surface area of the part. The defining contours are marked and sheet metal patterns are made from them.

One advantage of using the flexible pattern is that to make the other side symmetrical you simply turn it inside out and you have a pattern for the other side. The sheet metal gauges are for the final shaping of both sides.

The final piece will be made from 0.040 aluminum. To shape this stuff I had to use some high tech equipment shown in this picture.

Yes, that is really a tree stump and it is very efficient for shrinking metal. Stretching will be performed on a leather shot bag. Planishing the metal can done on an English wheel or planishing hammer.

Here is the flexible pattern being used to confirm the shaping or surface area of the final piece. The final shape is not quite there. You can see that it doesn't fit snug over the entire surface so there is more stretching or shrinking to be done..

The contour gauges to the right were made over the lines of the pattern when it was on the master shape. They will be used for the final shaping.

Control Cable Ends

JP — Tue, 26 Apr 2011 02:37:00 GMT

I am using A-920 control cables with 10-32 threaded ends. The clamp for the ends of the cables are difficult to find. I will admit, I didn't really look very hard. I took some 3/8 x 1/2 inch aluminum bar stock and made them. Each piece is 1 inch long. I clamped 2 of them in a vice and drilled a 1/4 inch hole between them and then used a 3/8 inch end mill complete the hole profile. They can be made with only a drill press if you use a 1/4 inch cap screw counter bore to make the square bottom profile. McMasters sells a drill - counter bore combination bit which would work as well.

The clamp pieces are shown with an A920 control cable resting in one piece.

Here is a picture of the handle end of the trim control cable in the fuselage. I opted to not use a throttle quadrant for the trim control. I made the handle out of 1/8 by 2 1/2 inch aluminum.

A piece of angle was formed from .032 sheet steel and welded in place to mount the control cable end clamp. My preference is to have the trim handle parallel to the upper longeron when the trim tabs are in line with the elevator at level flight. There will be a cover over the cable end and handle. There will also be an adjustable friction lock on the handle.

There will be a similar bracket made for the throttle control cable.

I am putting a window in the floor panel directly under the stick. It will be a 10 by 12 inch piece of abrasion resistant polycarbonate. It should help me to see what I am flying over.

The primer on the fuselage and the wing assembly has been hand sanded with 320 grit open coat sandpaper. It is ready for spraying an additional coat of primer. The first cross coats were applied with a foam brush so that it could be worked into the fabric. The primer is a latex based filling primer loaded with carbon for UV protection.

Beginning of the Wiring

JP — Fri, 25 Mar 2011 02:12:00 GMT

I mentioned beginning the wiring in the previous post but did not have any pictures to go along with it. I have added a copper ground buss 1 inch wide and 1/8 inch thick to the fuselage. I pressed a number of hardened PEM nuts into it so that I could attach all of the grounds to it. It is bolted and silver brazed to the fuselage. There is a good mechanical and electrical connection to the fuselage. The negative battery cable attaches to the copper buss along it's path to the engine.

The ground bus is positioned under the mounting tray of the radio. The radio is mounted into the sides of the fuselage. The radio is more than 10 inches deep. There is no room for it in the instrument panel. The fuel tanks sit closer than 10 inches from the rear of the instrument panel so there is insufficient clearance for the radio. The transponder will mount on the other side of the fuselage in similar fashion as the radio.

The rear of the instrument panel has the alternator disconnect relay and encoder converter module attached with #6 PEM studs. The encoder module converts binary coded altimeter data from the Dynon D180 to gray code for the transponder.

The wiring in the instrument panel will be done at a later date. There is still a number of mounting brackets to add to the fuselage for items like the boost pump, fuel filter etc. There will be no gascolator in this bird, just a high quality filter. I had initially considered using adel clamps for mounting all of this stuff but have since vetoed the idea.Permanent welded in mounting points are a much cleaner method. It takes more time initially but should make maintaining things easier.

Stripping the wing assembly

JP — Fri, 11 Feb 2011 04:38:00 GMT

I made a computer generated image of the plane about a year ago when I was trying to determine how I wanted it to look. When I painted the wing assembly I deviated from the image that I made. I made the blue paint edge on the top of the wing an ellipse rather than the straight line that I originally planned. It changed the overall appearance. The change in appearance bothered me so I decided to strip the paint and start over. In addition, when I did the final balance to the ailerons some of the epoxy leaked out and onto the painted surface of the ailerons, messing up those painted surfaces. They required some touch up as well.

I can attest to the tuff surface of the Stewart waterborn polyurethane paint. It took a considerable effort to strip it off. The schedule impact of this action shouldn't be too bad. The second time you do something it goes much quicker. I expect to be happier with the results.

Here is the bottom of the wing after stripping the paint off. I am adding new fiberglass. When I stripped the paint the original fiberglass became abraded. I stripped everything down to the wood on the wing assembly. I am using S glass cloth this time. I understand that it is 30% stronger than the conventional E glass cloth. It is also stiffer which made it easier to apply with the epoxy. The weight difference is greater but not all that much.

Another task that I did was to attempt to change the pitot tube from a press fit to a screw in device after the wing was completed. This resulted in an assembly that no longer held pressure. I messed up somewhere in this process. So, I plugged the hole for the pitot tube that was in the leading edge of the wing and relocated the pitot tube to the wingtip. I have initially installed loom tubing through the wing to the wingtips for the wiring of the navigation lights when the wing was put together. Adding pneumatic tubing as along with the wiring for the lights should be no problem.

The base for the new pitot tube is a simple aluminum block. It will share a mounting bolt with the sight gauge. The pitot tube will be fabricated from a section of 1/4 inch aluminum pipe. Everything is now easily assessable, the pitot tube base will be under the wingtip. Here is the new pitot tube assembly mounted at the wingtip.

The Dynon D-180 will be used for the instruments and engine monitor. It supports a two orifice pitot tube assembly. The dual orifice pitot tube generates a differential pressure and the Dynon D-180 uses it to display an angle of attack indicator that looks like an artificial horizon indicator. I don't plan to utilize this because I think it might be too distracting. I will start with a single port and connect it to both inputs of the Dynon D-180. The way the pitot tube is now installed to the wing I can easily change it later if I decide I want to.

I began the wiring for the plane. The battery wiring harness is installed in aluminum tubing where it will pass through the cockpit and in loom tubing elsewhere. The wire I am using was removed from a section of MIL-C-55483 cable. The wire is made from a few hundred strands of AWG 30 silver plated copper wire sized to become AWG 4 wire. It is high flex cable that was made for the military, our tax dollars at work here. With the silver plating I won't have to concern myself with corrosion problems. The battery cable terminals required a heavy duty crimping tool. I was lucky enough to be able to borrow one that could do the job. The heavy cable runs from the battery to the starter. The balance of the wiring will be with tefzel insulated wire.

Three years

JP — Wed, 22 Dec 2010 03:22:00 GMT

It appears that I am running behind my anticipated schedule. I expected to be finished within 2 years or 2000 hours, it is now 3 years from the time I received the plans and I have performed1550 hours of hands on work on this project. I let myself get distracted, there are no excuses. I have begun dual instruction in an Extra 300 in preparation of flying the One Design. I expect it will be flying soon.

The motor is a Lycoming roller cam IO360 with a front mounted prop governor. The heads were ported and high compression pistons were installed. It has a Light Speed Ignition, Air Flow Performance Injection and Sky Dynamics 4 in 1 exhaust. Just some basic enhancements, nothing unique. It has been run 10 hours on the dyno before it was shipped.

I installed the prop governor and the engine mount. The Lord elastomer mounts went on relatively easy. I have read stories about how hard it is to install a dynafocal mount to a Lycoming engine. I made a simple little tool to deflect the Lord mounts so that the AN7 bolts would install with very little effort. It worked better than I had anticipated.

Here it is deflecting the upper right mount while the AN7 bolt was installed.

All of the rubber mounts were installed within 15 minutes. I started with the lower right mount and then installed the upper left mount, lower left and then upper right which is shown above.

I utilized a 7/16 diameter bullet in front of the AN7 bolt. I deflected the mount sideways until the bolt went in with firm finger pressure. I torqued the bolts to 250 in-lbs as they were being installed. I torqued them all to 500 in-lbs after all of the mounts were installed.

Begin Fabric Covering

JP — Wed, 01 Dec 2010 02:57:00 GMT

The fabric covering has begun. The fabric has been installed to the fuselage. The fabric had the first shrink to 250 degrees and then the fabric patches and control cable fairings have been added. The empennage pieces have fabric on them as well. The whole process of applying the fabric goes relatively quickly.

I have used the Stewart System products to install the fabric.The two big advantages of the Stewart System is that there is NO stink and you don't have a race with the glue drying time when applying the fabric. You can get more information from them online. There are You Tube videos of the fabric installation with their products. I also recommend their waterborne polyurethane paint.

Fabric installation is relatively simple with the Stewart System products. Apply the adhesive to the frame and wait for it to tack up which takes about 10 to 15 minutes. Apply the fabric and lightly apply pressure where the adhesive is and the fabric sticks, no clamping is required. The glue remains tacky for a long time so you don't have to rush. You can lift the fabric and reapply it to get it exactly where you want it. When you are satisfied you can run the small iron at 250 degrees over the fabric above the adhesive to heat activate it. At this point you can still pull the fabric up and reapply the it if you need to but the fabric is attached more firmly. When you are satisfied with the placement of the fabric just apply the adhesive over the top of the fabric where it attached to the frame and wipe the excess off right away. The adhesive goes through the fabric and bonds to the glue underneath. The wiping helps eliminate any entrapped air. After a day the glue joint is very strong. Pull tests have shown the fabric to fail before the glue joint.

After the adhesive is cured for a day you can shrink the fabric at 250 degrees. Then make any cuts and add patches where necessary. Afterwards shrink the fabric but not the patches at 300 degrees and the final shrink at 350 degrees. At this point you can do the rib stitching and add tapes where necessary.

I utilized and IR thermometer to monitor the temperature of the irons. The alternate method of using a candy thermometer and silicon heat transfer grease is time consuming and risky. If you have any residue of the silicon grease get onto the fabric it can ruin the paint.

This method is quick and easy. The unit shown is a Flash Point IR thermometer. Most irons you can buy today have an internal shutoff. I didn't find that to be a problem. The shutoff timer is set to an hour. This is much longer than my attention span. I also check the temperature of the iron before touching the fabric each time I pick it up.

Preliminary Fitting of Some Skins

JP — Fri, 17 Sep 2010 18:05:00 GMT

The masking of the wings to add the blue paint took more time than I expected but masking it for adding the grey totaled about 10 hours. The finishing tape was very tedious to get right but here is the result.

After I finished the painting I had to balance the ailerons again. This time they needed only 126 and 147 grams respectively. This was accomplished using #8 lead shot and epoxy. This didn't take much effort to add the lead to the ailerons. I did, however, have some epoxy dribble out on the painted surface of the ailerons. Now I have to sand this off, touch up the paint and do another aileron balance.

Before putting the fabric on the fuselage I wanted to install anchor nuts in the areas under the fabric where they would be needed. This would be where the aluminum skins would attach to the fuselage, where the wing root fairings would attach and where the tail-cone attaches. I used #8 anchor nuts in this.

Some of the areas were a little tight for the rivet squeezer to get in and rivet the anchor nuts in place, so I made some custom dies using O1 tool steel. I didn't bother adding the clip at the bottom of the dies that holds them in the squeezer.

Fitting of the side panels was necessary at this point in time so I would get the location of the anchor nuts prior to adding the fabric in these areas as well. The side and bottom aluminum panels were cut bent and fitted into position.

Clecos were used where the anchor nuts would go to hold the aluminum panels in place. A 3 inch spacing or less was the goal for the screws holding the panels in place. The #30 holes were later enlarged with a #19 drill and the anchor nuts were riveted in place. I started out using an anchor nut as a drill fixture but quickly decided against continue using it after drilling into my left thumb twice with the #40 drill. A simple drill fixture was then made using some scrap steel to locate the holes for the anchor nuts.

There was some 2024-T6 aluminum left over after cutting out the side panels so I decided to make a cargo bay behind the seat under the turtle-deck. After all, I will need a place to hold the trophy during the flights home.

The bottom of the cargo bay is a couple of inches above the rudder cables. There is a cutout in the rear panel for inspecting the elevator linkage and the aft interior of the plane. It will have a polycarbonate window installed.

The shoulder harness attaches just above the rear corners of the cargo bay so the side panels were cut down and rolled to avoid any contact with the shoulder straps. The side panels are 2024-T0 aluminum.

Painting the Wing

JP — Wed, 18 Aug 2010 02:49:00 GMT

I picked up another HVLP paint gun, a DeVilbiss Finish Line 3. It works very nice. I used the Starting Line gun for the primer and had to sand a couple of iffy spots. The Finish Line 3 seems to atomize the paint better and gives more control. It is also a little bit easier to clean. The air baffle under the nozzle of the Finish Line gun is made different and comes apart for cleaning. I can also get any replacement part for the Finish line gun but not the other one.

I spent a couple of hours sanding the primer with 320 grit open coat sandpaper and finishing it with a maroon Scotch-brite pad. I painted 4 coats, 2 cross coats of Insignia White on the wings and ailerons. The paint nozzle was 1.3 mm, paint flow setting was 3/4 open for the first coat, 7/8 for the second, 1 full turn for the third and 1 1/4 open for the last coat. Ten minutes between coats with 15 minutes between the 3rd and 4th coat. That produced a real nice finish with Stewart Systems water-borne polyurethane paint.

I waited two days and masked the wing for the second color, Bahama Blue. It took me 5 hours to mask the wing and ailerons for the blue color. I made a painting template for the top of the wing a few weeks ago and I expected the masking to go quicker than it did. The template has an elliptical curve blending into a circular curve and then a straight line perpendicular to the wing chord. I placed some craft paper on the top of the wing and trimmed it to the outer edge to the wing. I then marked the desired curve on it and trimmed the template along the curved line. I also cut square holes near the curved edge so that it could be taped to the wing with masking tape. I taped the template to one side of the wing and followed the outer edge with 1/4 inch fine line masking tape. I flipped the template over and taped it to the wing on the other side so the top of each wing should match pretty close to each other. It was a real nuisance to apply the fine line tape with nitrile gloves on, but I did not want any contaminants under the paint. The picture shows the inside edge of the template. The wing is already painted and it was an after thought to show the template, here it is just before being trashed.

Here is the result of painting the wing as of today. This is the top of the wing.

The pattern on the bottom of the wing consists of straight lines so I simply used a tape measure to lay it out. Here is what the bottom of the wing looks like.

The pictures do not give a true rendering of the color and shape of the painted wing. The space in the paint area is limited so the camera angle is shallow. Both end stripes are about 12 inches wide and each of the 3 center stripes are 25 inches wide, but in the picture they don't appear that way. The pictures were taken under fluorescent lighting so the color is off.

As long as each side of the wing appears different and the judges can tell the difference I suppose that is all that matters. The ailerons are also painted with these colors. In a couple of days there will be a small amount of gray added to the tops of the wings and ailerons. The ailerons will then be balanced again and installed on the wing assembly.

I mentioned in the last posting, the seat belt attachment points look much better when they are properly painted.

I also added the back end of the slobber pot overflow tube. It drops through the fabric right before the front battery bracket.

It is installed now because it has to pass through the fabric. It is attached to the fuselage frame with Adel clamps as shown.

Last minute details before fabric

JP — Sat, 31 Jul 2010 23:15:00 GMT

Last month I mentioned I was told to put the paperwork for an N number through early, as much as six months early. Well, I got my N number a week after I sent the paperwork in, N537JP. So much for needing a lot of time.

With my reserved N number finally official I made up the stainless ID plate that is required at the aft of the plane. I used the EAA plate and stamped on the appropriate information. I then proceeded to weld on a backing plate to rivet the ID plate to after the fuselage is covered and painted. This is something that was left off of the prints. The rivet holes are punched on the backing plate to fit the ID plate. I have also stamped the plane serial number on the backing plate.

I will be using a Hooker harness and the seat belt attachment plate on it has a round bushing that will allow the seat belt attachment plate to articulate. I felt that the seat belt attachment point on the plane would be better if it was a dual plate rather than a single plate for each point, like a clevis. I decided to add an extra plate for each point. The spacing is 0.35". It was a bit of a pain to install at this point in time but it is done and primed. It will look much better after it is painted.

I also got around to welding in the fabric support brackets around the strap hinges. It may not be pretty but it is functional. These were primed with etching primer and epoxy primer after the picture was taken.

I have also spent many hours sanding the surface of the wings and ailerons after applying the fiberglass and epoxy. They are smooth and ready for paint. I will be using Stewart System waterborne polyurethane paint on the wings and on the fabric.

I believe I am ready to apply the fabric to the fuselage. I plan to use Stewart System for the fabric and finish. A friend last year used it for his plane and has only praise for it. It is compatible with the urethane paint on the fuselage.

Time Delay

JP — Tue, 15 Jun 2010 03:03:00 GMT

It has been a while since my last entry to this blog. Some of the things I was doing were not directly related to the One Design build. The air compressor quit so I purchased a large one and plumbed the workshop with nylon tubing and extra air filters. I used the submicron filters for the paint area and for the plasma cutter and the normal filter for the rest of the shop. We had a premature thaw this year and the workshop flooded a couple of times early this spring. Nothing was damaged in the flooding, it was just a nuisance and a delay both times. So much for those excuses, I also became a bit complacent.

I was not able to get a quote from Barrett on a front governor Lycoming engine. I went to Lycon and ordered a roller cam IO-360 engine, ported with 10:1 pistons installed. The price was comparable to ordering direct from Lycoming but they have a better reputation and give you more options. They were recommended by Rob Holland. The one thing I added was to have them run the engine for an extra 8 hours on the dyno to start the breakin. Hopefully this will reduce the possibility of premature engine failure on the first flight.

I also started building a smal power hammer so I can shape and shrink aluminum easier. It is not far enough along to take any pictures yet. I am building the buck for the cowling. This will take a little time. I started with the shape of the firewall and the shape of a Pitts nose bowl for clearance at the front. I have to change the shape of the nose to something I like and then form the aluminum to match it. I like the Dodge cowling but can't get one... so I will attempt to make one from aluminum. I am not a big fan of fiberglass parts.

The other things that are being done are planning the electrical system and ordering the parts. I will use the B&C 8 amp alternator mounted to the rear of the engine. The voltage regulator, fuse panel, boost pump and stuff like this all have to be added and their locations have to be selected. Quite a bit of time has been expended planning the paint scheme. I think I have a reasonable one in mind now. I have a computer model of it but you will see the real thing here in a few months.

For the instruments I will be using a Dynon D-180 with the super bright screen. This will provide the engine monitoring as well as the flight instruments. With a Garmin digital transponder, radio and GPS the instrument panel should be clean and functional.

I have added the fiberglass to the surface of the wings. I should have done this right after I completed the wings instead of waiting. Epoxy resin has a shelf life of about a year so I had to purchase fresh epoxy. Procrastination has a cost.

I have sent the paperwork to the FAA to register the plane. Not sure how long it takes but I was told to do this 6 months early.

I have a friend with a Pitts S2A who has just had the bushings holding the fuel tank in place break at the welds. It is the same in the Pitts as in the One Design. The repeated bouncing around of the fuel in the tanks puts a twisting forces on the attachment bushings. The Pitts only has one tank. I am planning an alternate method of attaching the tanks to the fuselage which should eliminate some of the twisting force on the bushings attached to the upper longerons. More pictures next time.

Sheet Metal Forming and Stuff

JP — Fri, 12 Feb 2010 03:24:00 GMT

It is time to make the fuel tanks. The plans call for the forms can be made from 1" tempered masonite. The 1 inch thick masonite is not readily available so I laminated some 1/4 " masonite together. The commonly available contact cement is water based and it doesn't stand up to the hammering. I used a urethane foam adhesive, Gorilla Glue, to laminate the masonite sheets together. Hardwood such as maple or oak is another option to make the forms from. It can also be more cost effective.

I have made the ends of the fuel tanks a couple of times. The first time they had a small radius to the bend and I was a little concerned about it. I used a 3/8 inch inside radius on the second set of fuel tanks ends. That looked much better to me.

The rawhide faced mallet does the preliminary forming. A little heat is used to assist in the shrinking of the metal around the sharper curves at the edge. Just the edge of the area to be shrunk is heated.

The temperature should be just enough to anneal the aluminum. When a Sharpie pen mark changes color that is about the correct temperature. The Sharpie doubles as a cheap temperature crayon.

The horizontal stabilizers were attached and held in position with steel jack chain and turnbuckles. The temporary tail brace assembly was brought up to around 50 lbs tension and they were adjusted so the parts of the empenage were level and perpendicular to each other.

Dowel pins and safety wire was used for the end fittings. This gave me edges to easily and accurately measure between. It gave me the pin center length for the streamline tail brace wires. With the empenage aligned both sides measured the same which was a good indicator. The lead time for the wires can be up to 12 weeks.

Two Years Under Construction

JP — Mon, 04 Jan 2010 01:51:00 GMT

That's right, it has been two years since I started this project. My goal was to be finished in this time frame but I didn't meet that scheduling goal. I have a little over 1200 hands on hours on this project right now. The first year I had 700 hours. It will take a few more months. I expect to be flying this plane this summer. I have ordered a Whirl Wind 200C prop and governor just before Christmas. It is due to be shipped to me by the end of February or beginning of March.

The engine mount is welded and it is in alignment on all 3 axis. All it needs now is a little paint. The heat for the paint booth is just about complete. The chimney for the paint booth furnace was just installed a few hours ago and the plumbing should be finished this week.

When I was reviewing the fabric installation I had asked a friend who has done fabric work how I close the fabric in the area around the strap hinges. The suggestion was to make a metal or plastic strap that attaches to the tubing on either side of the strap hinge to glue the fabric onto. Here is what I made.

It is made from 0.025 chromoly, the same material as the fuselage brackets. This way they can be welded in position. The flat pattern is shown along with the partially formed pieces. The bends have a 1/8 inch radius so the need for anti-chaffe tape can be kept to a minimum. The back edge will be trimmed and rolled over completely after it is welded in place around the strap hinge. The bend relief holes are 3/8 inch diameter. There is probably an easier method to acomplish this task. This seems to be a reliable solution.

The firewall is cut and drilled. I am waiting to receive the aluminum angle to go around the edge of the firewall. After the firewall is installed I can begin cutting and assembling the fuselage skins. In the mean time I will be making the turtledeck and side formers.

The form blocks to make the fuel tanks and fuselage forms have been made by laminating four layers of 1/4 inch masonite. I first attempted to make the form blocks with medium density board. The forms were easy to make but they didn't hold up at all for the fuel tank ends. Now I will become a tin knocker for a short time.

Engine Mount

JP — Wed, 02 Dec 2009 00:36:00 GMT

There has been a minor delay in posting this entry. The roof on the trailer I planned to use as a paint booth had collapsed in a storm last winter. I had to build a paint booth for this project before the weather turns ugly. While it took a few weeks to complete it is more conveniently located than the previous one, right outside of the shop door.

I plan on ordering an engine from Barrett Precision Engines. I have spoken with Allen Barrett a few times already. We covered a lot of details on exactly how I want the engine, cold air induction, forward prop governor etc. They also balance the engine so it will be custom made to my requirements. When I spoke with Lycoming they only gave me a choice of front or rear mounted prop governor on the Thunderbolt engine.

The engine mount is presently under construction. The sockets were bolted to Lycoming case with dummy aluminum mounts. The spacing is 0.645” which is the compressed size of a Lord mount, socket face to engine case. I have made a plug with a small hole in it for the accessory case end of the engine and another plug for the prop end.

The plug for the prop end will hold an alignment laser.

The engine mount will be tack welded together on the forward end of the fuselage. This will eliminate the need for a large hammer to install it later on. The laser will be added to the front of the engine case and point toward the tail post during the assembly of the engine mount. This will insure that the engine is aligned with the fuselage. The engine mount will be custom made to the fuselage. Trimming the plane for flight later on should be relatively simple with the engine correctly aligned.

Here is the engine case in position. It is held by the sling and the clamps. The roll axis is aligned by equalizing the distances from the jugs to the angle clamped to the top of the upper longerons. The pitch and yaw alignment is checked with the laser dot on the tail post.
Wedges are used to shift the position of the case. The alignment is checked after each tack weld to insure proper alignment.

When the engine mount is complete I will bolt on the firewall to the fuselage and the jugs to the case and begin fabricating an aluminum cowling. I expect a few months delay in getting my engine so this will reduce the construction delays. The next 3 or 4 months has very poor flying weather in this area anyways.