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After building many kits over the years I have decided to try a Twin. I have two nice O.S. 40SF engines sitting around and decided a while back to focus on the Duelist as a good twin to start. After looking at the Pica Kit and all the odd thrust and incidence angles inherent in the MkI design I decided I'd purchase the M.A.N. plans and build the MkII instead. This will be my first plans build. It's designed with 0,0,0 and reportedly flies just as well as the PICA version, only faster! It also flies better inverted.
The plans came after about a month(!) rolled in a sturdy tube with a photocopy of the original build article that was essentially some comments about the history of Dave Platt's design and, though interesting, not real helpful to a builder. The first thing I noticed was that while the plans were very well inked and professional looking, all the rib and former templates were nested atop one another. The only way I could think to make templates was old-fashioned tracings - ugh, what a pain...
Next I noticed there was no materials take-off so it took several hours to make the list, then convert it into something I could actually buy from a wood supplier. I ordered my wood from Balsa USA and it arrived promptly, well packed, accurate, and most important, the quality was excellent.
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Joined: 10/14/2005 From: Austin,
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While awaiting my wood to arrive I set about the dreaded task of making tracings of all the ribs and fuselage formers. I traced using a mechanical pencil for obvious reasons and it didn't take as long as I thought it would. However, when I went to make photocopies on my fax machine the pencil didn't get picked up so I had to darken all the lines with a pen.
Ok, with that problem licked I ran the originals through the fax machine and they photocopied beautifully! Then I checked them against the originals in front of a strong light and discovered large distortion in the top to bottom direction on the copies.
Ok, took 'em to Kinko's who have a bit fancier copier and voilla, problem solved!
Next I cut out each rib and former and arranged them onto my sheetwood in the most efficient configurations I could think of. While holding them on the wood upside down, I transferred the photocopied image by dipping my finger in lacquer thinner and rubbing the image. Finally, a technique that worked great the first time I tried it.. It even worked great on plywood.
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I decided to start with the fuselage first. Using a sharp Exacto knife while watching TV I managed to cut out all my bulkheads in short order. The 1/8 ply bulkheads were cut using a scroll saw. Some folks swear by their rotary sanding tables for this operation but I find it takes too much material away when sanding balsa shapes and creates more work and clean-up than its worth.
Next I laid out my pushrod arrangement through the bulkheads. In the past I've kinda fudged this, often waiting till the fuse was framed to install flexible plastic rods. This time I plan to use carbon graphite rods for better precision and less slop. Carbon doesn't like abrupt bends so I drilled holes where they will intersect each bulkhead. I ended up having them cross near the tail so I could keep them inside the fuselage as far back as possible.
Next, I mounted each bulkhead on a straight board. (Kinda brings new meaning to the term Building Board.) The tough part was keeping the bulkheads straight while gluing them down to the board. After laying out a centerline on the board with a station line for each bulkhead I drew a vertical centerline down each bulkhead and used a laser-level to verify. I had just enough room to slip a triangle behind each bulkhead to get that third and final dimension straight. Hey, this just might work....
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Joined: 10/14/2005 From: Austin,
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Hi Sscherin, Yes the Duelist is quite an airplane. It reminds me of the pattern ships of the '70s converted to a twin. Other than the rather involved fuselage layout she builds much like a Kaos, Dirty Birdy, etc. I love the shape of the fuse and consider it worth the extra effort to have such a streamlined shape.
In order to complicate things as much as possible I've decided to go with pneumatic retracts, probably Spring-Airs.
The one nit I have with the looks are the engine nacelles. Platt designed them as basically a plywood shoe box glued to the outside of the wing. He did it to make things easier on the builder I guess. After studying some Royal plans of the B25 and other multi's I think I might have come up with something a bit more graceful. We'll see.
One thing everyone agrees on: This is a fast airplane!
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Joined: 10/14/2005 From: Austin,
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Here is a picture of a Pica DUELIST I found on the internet. The builder was certainly going for speed with this rig. Note the rear-facing exhaust engines and tuned pipes!
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Welcome to my thread David. I've been doing some structural stuff over the weekend. I've attached some progress shots of the build. The bones of the fuselage are starting to take shape. Reminds me of a dinosaur skeleton. Although this is my first plan build its going pretty smooth at this point. Not much different than building from a kit. Having each bulkhead perfectly symmetrical at this stage isn't critical but you do have to emphasize overall straightness - I've never built a banana yet and don't plan to start with this plane. I really like this upright building method. It opens up the possibility for much more intricate shapes in the future.
You might have noticed the Titebond wood glue in the background. I rarely use CA glue for anything more than tacking parts together now. The CA is so brittle parts can be snapped off and repositioned. After I'm satisfied things are straight I "roll" a generous fillet of Titebond at every joint with a toothpick. It dries in 15 minutes, makes for a MUCH stronger airframe and the wood glue is $8 a pint (!) at home centers. Heck, they even sell it by the gallon for not much more. If your into giant scale there's some serious savings...
Very nice pics - keep posting! I have the plans myself, and intend to build one of these one day. The pics make my fingers itch - building the fuselage looks simpler than I thought.
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Joined: 10/14/2005 From: Austin,
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I'm glad to see such a healthy interest in this subject. I started the thread over in the scratchbuilding forum but didn't get much interest. I usually hang out in the scale and pattern forums but a Duelist really doesn't fit there either. With the production of interesting kits drying up its only a matter of time before kit builders are going to transition to plans building so....
...Onward through the build. I dropped by my LHS yesterday and bought my pushrods. I didn't care for the stuff available so I came up with my own. It consists of a piece of antenna tubing and a 1/16" piece of music wire. I will eventually solder a threaded connector on each end. I may still go with carbon fiber rod to save weight. Either fit. It's important at this stage to get the guide tubes in place and the pushrods moving freely with no resistance. The holes I drilled in the bulkheads earlier were suprisingly accurate. I did elongate 2 holes slightly and it made a noticeable difference because the antenna tubing clearance is much less than pushrod tube. Just eyeball it and look for humps.
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Joined: 10/14/2005 From: Austin,
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Without any build instructions its difficult to know when the best time is to remove the fuselage from the board. The tail still feels a bit flimsy. One step I had been dreading was adding the fuselage bottom. I finally decided to leave the fuse on the board. I kept the wing trailing edge bulkhead and tailpost glued to the board and sawed away everything else in between. I then slipped the fuse bottom in and glued everything with Titebond. Now that wasn't so bad..
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Building a DUELIST MK 2 From Plans! - 
