Back in 1992, Tom was given a Pica Duellist MKII that a friend of his built from the plans that were drawn by Dave Platt. It was fuel soaked when he got it, so he fixed it and recovered it. Tom flew that airplane a lot, but he crashed it after changing the receiver. The ailerons were reversed and since he didn’t do a preflight check, he didn’t notice it before take-off. After the crash, he kept all the salvageable pieces in a small container in his building area affectionately known as the Duellist bucket.
After sitting for decades, Tom will be using the parts that are left to resurrect his old favorite so they can fly again!
Follow along below with Ron and Tom as they both build their Duellists. There will be some differences in building techniques and power systems, so it should be fun to watch. Ron will be building his all electric. Instead of retracts, he will be converting it to a fixed gear tail dragger. Tom will be building his airplane per the plans, including nitro engines, and Robart air retracts for a more traditional Duellist.
Table of Contents
Tom’s Duellist Build
The Wing.
Drawing without cut lines for the Duellist ribs. This will be cut out of 4 pieces of 1/8″x4″x36″ balsa.Drawing with cut lines for the Duellist ribsClose up of the lightening holes Tom wanted in his Duellist ribsHere are the ribs after cleaning them up. Ron cut these with his homemade laser cutter! A few minor adjustments and they were great!I’m using 1/32 aircraft ply for my shims. Close up of one of the “adjustments” I had to make on a few of the ribs. Some were a little short at the leading edge. Nothing a piece of folded-up sandpaper and shim couldn’t fix!Left hand wing panel laid out and glued. Had to make a few adjustments to some of the ribs. Check out those fancy weights! BB’s and a food saver make great custom weight bags!Two panels ready for the top sheeting. Another view of the two wing panels. Nice and straight and same length (even with the error on the plan, lol!)Trimming the sheets to assemble the wing skins.Getting the skins ready for the wing.Trimming the leading edge using a Master Airscrew razor plane.So many shavings.Sheeting on one side.Another angle.This is the template I used. Its .010 G10 fiberglass. Expensive, but what I had available that was transparent. When the bottom of the wing gets sheeted, the mounts for the gear and servo would be hard to locate. So I traced the cutouts with a few reference lines and the holes for the gear and servo mounts to line it up.
Once the template was ready, I put screws in the holes in the mounting blocks in the wing. Next, I lined up the sheeting with the trailing edge and laid it on the panel. I pressed down lightly in the areas where the screws were, which left their impressions in the shaft balsa. When I removed the sheeting, I had nice indentations to line up my template.
Once I had everything lined up, I marked and cut out the sheeting for the gear and servo.And here it is all glued up and drying. I’ll pull it off the table after it sits overnight to fully cure. Once that’s done on both panels (the first one is done and off the table), I’ll finish up the gear cutout and work on lining the wheel well with balsa.
Not too shabby! I still have to finish up the relief for the gear leg and wheel, but I can do that with the sheeting glued in place.
Here’s what I’ll use to line the wheel wells. I just wet some leftover wing sheeting with Windex (the good stuff, with ammonia!) And rolled it around a can of about the same wheel diameter. Once dry, itll be cut to fit into the wheel wells.
Here’s my attempt to start cutting out the gear wells. Starting by setting the gear in place and marking where the axle touches the wing skin. I then drew an outline the same diameter of the wheel with the center at the point where the axle touched the sheeting.
Here I had to trim the sheeting to clear the coil on the gear wire.
Here’s the cutout with the gear removed.
The gear cutout in relation to the aileron servo cutout.
We have a wing!This is the fairing I built to smooth the area on the belly at the fuselage/wing transition. Balsa is so nice to work with!
The fairing after some smoothing. Here you can make out the blocks I added after-the-fact for the wing mounting. I had to open up the sheeting to add the plywood blocks.
The Nacelles
Pic of the mock-up after basic nacelle construction was complete. I was still planning on side mounted engines with the pipes running down the R/H bottom side of each nacelle.
Another pic of the mock-up after basic nacelle construction.Another view after initial engine mounting. Here is where I discovered the pipe on the #1 engine would interfere with the left main gear leg. Luckily I only had one engine mounted (so not many extra holes in the firewall)!The number two engine would have cleared the gear with no problem.The final arrangement with the engines somewhere between side-mounted and inverted. Pipes will run right down the centerline of both nacelle bottoms.
Here I’m moving forward on finishing up the nacelle construction. Also getting a start on the built-up cowlings.A lot of balsa will need shaping when this is all glued together, lol!Cowlings, and forward section of both nacelles nearly complete. I’m starting to dread the shaping on the aft sections! Had to mount the props, pipes and spinners to get an idea of how it was going to look with the exhaust location. I like it!
Front view with the pipes and props in place.I really dig the exhaust locations.My belt sander got a good workout!I’m incorporating the aft pipe mounts into the rearmost hatch hold-down location. It’ll be a fairly slick installation.Here’s a side view to illustrate how much work is left to do on the aft sections.Starting the arduous task of finishing the aft sections of the nacelles. I have to admit, this went a lot faster than I was expecting. My belt sander got another good workout! Progress shot of the number two engine nacelle.Pretty much done with the nacelles here. The aft sections weren’t as bad as I was expecting. I think they look good.Side-on view of the finished nacelles. It reminds me of a turbo-prop exhaust like you’d see on a commuter airliner. I like it!Here they are with the pipes in place. The wing is pretty much complete here. I can already hear the engines screaming in unison!
The Fuselage.
Starting on the fuselage. The standoffs Ron 3D printed for me are visible here. Thanks Ron!
Here’s a cool picture to illustrate how straight the Adjusto-jig allows me to build the fuselage.
Here I’m checking the alignment of the fuselage crutch to verity that it is straight. This is an important step, as most of the key measurements are taken from this part.
Here I’ve begun building the upper portion of the fuselage. I’m trying to build as much as I can with it still on the jig to keep everything straight.
With as much of the fuselage built as possible on the jig, I couldn’t resist setting it on the wing for a glimpse of that famous Duellist shape.
Working out the details of the radio and retractable gear install as this area will be hard to get at once sheeted.
Here is the final location of the air tank. I should get several cycles of the gear per charge.It’s tight, but everything fits.This is how I formed the fuselage sheeting. Once the sheets were glued together to make the skins, I trimmed them slightly oversize and soaked the outer surfaces with Windex (the good stuff with ammonia). I then rubber banded them to the structure and allowed them to dry. Here are the skins after they were dry. It’ll be a lot easier to glue these to the fuselage now that they’re pre-shaped! And here are the skins glued to the fuselage. I used a combination of CA and Titebond to secure the skins. Working slowly, I used the Titebond in any area that I couldn’t reach with the skins on.
Getting closer. Much sanding has been done at this point. You can see the block I used at the stab saddle area. Once sanded to shape, I’ll remove it and trim for use as the fillets for the vertical/horizontal stab interface. Finishing up the last few blocks on the fuselage and started sanding. Lots of sanding. You can see my oops on the nose block, lol! A little too much sanding there.
Here the wing is mounted, and the empennage is setting up. The wing is mounted via plywood blocks located in the fuselage. I decided to deviate from the plans and use 1/4 x 20 nylon bolts instead of the 8/32 steel bolts for wing mounting.
And here is the total airframe weight minus all the gear. Nearly 4 pounds! Not bad I think.
Getting ready to start on the wing fillets.The wing fillet base, made out of G10 fiberglass, is glued in place. Notice the plastic wrap to keep me from gluing it to the wing.The wing fillet under construction. After gluing the fiberglass base to the fuselage, I gradually built up layers of epoxy followed by spackle to get the shape right. I would not do it this way again. I should have built the fillets out of balsa! I’m sorting out the nose gear situation here. This is the point where I realized the nose gear leg was going to be loooooog!I had to get creative with the nose gear installation. I had to come up with a unique solution for a REALLY long nose gear leg.Since I deviated from the plans and lengthened the main gear (for more prop clearance since we fly off a grass strip), I just added a Robart Robo-Strut to the existing nose gear wire. Time will tell if there’s too much ‘give’ in the installation, but it works on the bench, lol! Here’s a final solution to the nose gear. No, the picture isn’t distorted, it’s as long as it looks, lol. BTW, that front retract unit is from the original Duellist!Trimming the canopy to fit.There wasn’t a lot of ‘meat’ left to mount the canopy after trimming it so it would fit nice. So, I added some balsa to the cockpit sides to provide a mounting flange for the canopy. The canopy is a 13″ WWII unit purchased from Sig Mfg. Empennage is done and hinged! I’m using Robart pinpoint hinges on this build. They work pretty slick and after you develop a technique for working with them, they’re easy to install. Strong too!
This is what I had on-hand to work with for the covering job. I chose Cub Yellow, Metallic Teal, Aluminum, Black and White. The rudder is covered! Got a pretty good start on the fuselage. The overall color scheme is starting to take shape. Those wing fillets gave me some trouble.I think I’m going to like the contrast between the yellow/teal and neutral colors. The fuselage is covered! I still may play with the trim a little on the horizontal stab. I feel the green could be a little wider.
One of my least favorite tasks: covering the corners before applying covering to the large areas. This will ensure a fuelproof joint so this Duellist doesn’t end up fuel-soaked like the inspiration for this build!Center, lower section covered. I love Monokote!This is the template I made to get the seams even between the white/teal. Worked like a champ!This is the template I made to get the seams even between the white/teal. Worked like a champ!Adding the white “Chinakote”. I am a fan of this stuff. It’s cheaper and works very similar to Monokote.If your 21st Century iron stops working, like mine did, check the wires as they go into the handle…If your iron is like mine, the wires going into the handle may have been pinched by the strain-relief. Mine were nearly cut in two.I cut off the pinched wires and re-soldered them to the board. Good as new!Here the wing is pretty much done with covering. I still have to add some trim though.Another view before adding the final trim pieces.I just had to get it outside to see it in the daylight.She looks good in the sun! The yellow really ‘glows’ when the sun hits it.Added the GoodWill pilot and glued the canopy on. I use RC-56 (also known as Formula 560) for this. I’ve also installed all of the radio, engines and gear at this point.I wonder what he’s thinking?Just a little bit of trim left to do.DONE! Notice the snow that prevented the maiden flights as planned.The snow kind of wshed out the white parts on the airplane, but I like how it turned out.Ready to fly!
Ron’s Duellist Build
The Wing.
Plans and the wing rib instructionsThe plan was used to space the wing rib supports on the wing jigThe wing jig is properly spaced and ready to start building a wingThe wing ribs are cut, and ready for assembly!Ready for sparsThe ability to tilt the wing makes it so much easier to buildIt’s mostly been assembled with CA glueAlmost ready for sheeting on the bottomGetting ready to make the wing sheetSeveral ribs broke when the wing was in a vacuum bag testing to see if it would work to glue the wing sheeting on.Pieces from the broken ribs.
The Wing. Take Two.
At this point, since we bought a new laser and the wing sheeting hadn’t been added to the wing yet, I decided to start over and build a new wing! After breaking it in the vacuum bag, I wasn’t happy with how it glued back together and figured this was a good time to start over. Instead of using balsa for the ribs, the new wing will be constructed with falcata ribs (at least I think that’s what it’s called!)
Starting over from scratch! New wing ribs cut and ready for assembly.This time I’m building the wing correctly, with dihedral, so I had to set the Ajusto-Jig to the correct angle.Another shot showing the angle.The ribs are ready for spars!Starting the spars.A different view.Trailing edge getting glued on. So far, I’ve only used wood glue for the assembly.Trailing edge finished.I love being able to rotate the wing the start on the leading edge!Leading edge on!My old wing is sitting in the background. I’m not sure what to do with it yet.
The Wing. Take Three.
I ended up with a heck of a bow in the trailing edge of the second wing. That’s because of the incorrectly drawn parts that were traced from the plan. I ended up going through the files and re-drawing them with the correct alignment of all of the wing spars, leading edges, and trailing edges. That made building the third wing quick and it went together really well. No warps or bows in this one.
Lining up the ribs on the jig. The main spar notches are nice and straight!The rear notches are nice and straight, too!The leading edges are nice and straight.The leading edge is straight.The main spar is straight.The rear spar is straight.The trailing edge is nice and straight.Getting ready to install the sheeting.Glue applied.The vacuum line goes inside the wing for even suction.Starting to vacuum.Showing 5 in/hg vacuum.Another shot. Under vacuum.The top while under vacuum.Another shot of the hose in the ribs. The trailing edge is still straight.Same with the far side.Sheeted!No bow in this trailing edge.Glued up nice and straight.So is the other side.Marking the servo location in a clear piece of lexan so the location can be transferred to the sheeting. I use a pin to mark the edges before putting the sheet back on.Transferring the holes into the sheeting so the servo hole can be cut out. Leading edge glued and pinned.Leading edge glued and pinned.Leading edge glued and pinned.Vacuum bagged for a nice and tight fit. Vacuum bagged for a nice and tight fit. Vacuum bagged for a nice and tight fit. Leading edge on!Leading edge shaped!Another view. Lots of balsa curls after the leading edge was formed.
The Rear Stabilizer.
Getting ready to glue up the rear stab.Glued up and drying.Since I change my mind a lot, I decided to make the stab a little longer and added a rear section to extend it. Beautiful joints. I don’t know why Tom was making fun of me for them!
The Fuselage.
I was finally able to start on the fuselage. Hopefully I only have to build one of these!
3D Printing the custom standoffs for building the fuselage on the Ajusto-JigLining up the standoffs for the fuselage.You can see all 3 wings in the background!Starting the fuselage.Stringers on.Another angle.The sides are rough cut and pinned on, getting ready to be glued. The sides are rough cut and pinned on, getting ready to be glued. The sides are rough cut and pinned on, getting ready to be glued. I didn’t get any pictures of it in the bag. I used tape to hold the bottom sides tight while the glue dried. Marking the wing saddles to cut out of the fuselage sides. Marking the wing saddles to cut out of the fuselage sides.Trying to keep it stable as the epoxy dries on the horizontal stab. The horizontal stab is glued on. Waiting for the glue to dry on the vertical stab.The square keeps the angle right. (get it, right angle?!)checking fit for the rudder. This is what happens when you get a little too aggressive with your sander. Oops.The stack of balsa I used to make the nose.This is apparently not a good way to make a nose. Waiting for the glue to dry.Tom really made fun of me for this.Trying to get an estimate on weight. Just over 7 lbs!Starting on covering. Metallic blue, silver, and carbon fiber. Rear horizontal stab and vertical stab covered. Another shot.Nose is covered. It was difficult. Dark metallic silver trim added.Starting on lower fuselage. Another angle. Shrinking the film.I didn’t like the blue vertical stab, so I changed it to the carbon fiber covering.Empennage all trimmed out.Fuse is finished!Fuse is finished!The landing gear is sandblasted, and ready for paint.With the hatch removed, you can see through the fuse! Starting on the bottom of the wing.Top of the wing nearing completion.Test fitting wing with landing gear and pilots!The plug I made for the canopy.Forky and Duke Kaboom, ready for flight!Checking CG. With no weight, it balances at 3.75″ back from leading edge.
The Final Product!
The original plan was for Ron and Tom to maiden their Duellists on January 1, 2021. Unfortunately, mother nature decided it was more important to have an ice storm that day. The maidens should happen in the next couple days, depending on weather, so check back for updates!
Ice on the trees, Jan 1, 2021No flying with weather like this.
