This one started, like the VeeBee, being modelled with Metasequoia in 3D. I like using Metasequioa for modeling an original design because it is easy to learn and use. A model can be created fast and also easily changed. The design i had in mind was to create a fictitious twin engine racer that looks like it would have had two big V style engines mounted to the wings with a cockpit that would be as far back as possible making it look as though it was postioned back there to offset the weight of the engines like a GeeBee. I also wanted to give it a '30ish look, you just gotta love that era in avaition. Some of the most beautiful aircraft in my opinion were designed during that time. This model was modified and changed over time quite a bit from the original to how it looks here.
Basically the same thing was done as with the VeeBee, i saved the model in Metasequioa as a DXF and then imported it into TurboCad. This time the only part of the 3d model i ended up using was the fuse to get it's compound curvy shape. This pic shows that slices were taken from the fuse and nacelles. The nacelle slices weren't used as they are really just eclipses. The one problem with the slices in the pic and what happens when the model is saved as a DXF is that Metasequioa will used DirectX or OpenGL to smooth the surface of a model, that isn't retaind in the DXF file, model surfaces end up being composed and displayed as a bunch of smaller flat surfaces. I just tried to split the difference between the low and high spots using the bezier curve command in TurboCad to get smooth shapes for the formers again when tracing over the slices. The real designing and drawing was done in TurboCad, areas and moments were calculated and changed a little when needed as well as incidences. The actual rc model won't be an exact copy of the Metasequoia model, but as close as i could get to that and something that will hopefully stand a far better chance of flying.
The CAD plans now have been drawn and redrawn over the last couple years in between other projects, etc. Even though the designing stage was off and on, this one has always held my interest and I eventually wound up with two versions, one with an open cockpit and the other being enclosed like the Metasequoia model. The drawn parts of the fuselage, engine nacelles, wing center section and floats were put together in 3d (pics below) within TurboCad 9 Professional to check for mistakes, parts fit and the transition of the former shapes. A cutting file was also put together to send to AK Models to cut a kit for me.
Link to RCUniverse build thread.
Now this is where the build starts, hopefully, culminating in at least a flyable radio contolled aircraft. If not i guess it will be back to the drawing board.
I received a good size box from AKM containing a whole lot of laser cut goodness inside. I love this part, opening the box to check out all the laser cut parts that have been cut with the accuracy and intricacy that band saws, scroll saws, and disk sanders can't quite achieve (at least not by me). I also had a set of plans printed by Universal Reproductions located in Kamloops.
The fuselage was started first since i really wanted to see it all fleshed out in wood. Most of it was glued together using just aliphatic resin (carpenters yellow glue). The fuselage is built by laying the crutch flat on the building board and gluing the wing saddle formers and bottom fuse formers into place and then the keel pieces. The top fuse formers and keel pieces were then glued on next. the rear top portion of the fuse has to be removable for access to the rudder and elevator servos, those rear top formers must only be temporarily glued just enough to allow for planking.
Planking of the fuse was next. This is the only method i know that works good to sheet a fuselage of this type, especially the rear top and bottom sections of the fuse. I used 1/4" x 3/32" balsa stripped from sheet stock for planking. A good article on planking can be found here, it can take a little practice to get results that don't require much filler afterwards. This was the second time i've done planking on a plane, that how-to article really helped alot. After the planking, the fuse was filled where needed and sanded smooth, it was then glassed with light glass cloth (.5 oz/sq yard) and water based polyurethane.
NOTE: I switched from building the open cockpit version to the enclosed cockpit through the build. The last fuselage photo shows that the fuse with the enclosed cockpit.
The fuselage also needed a nose cone made. I made a plug out of blue foam and balsa that was sanded to shape and then glassed using epoxy resin. The plug was wet sanded to a really smooth finish and then used to make an epoxy glass mold for making the epoxy glass nose cone.Two engine cowls were made the same way, making molds definitely makes for quite a alot more work but was worth it. The full story here. Now i have two identical cowls! This mold only differs from the nose cone mold in that it is a two piece instead of a one piece.
Build is still on going, to be continued....