Archive for February, 2015
Progress continues adding the stringers to the fuselage, although i did run out of stock of 1/8″ x 1/8″ balsa stick. So a trip to the nearest model store for supplies saw me clear them out of their paltry supplies. This allowed me to add a few more stringers to the rear section, forming up the tail wheel area and the waist gun areas.
Stock was running low yet again so i thought it better to start to build the stabilizers as these also need 1/8″ x 1/8″ strip stock. As well as fitting into the rear section before i get much further along in the build.
The keen eyed person may have spotted the model PBY Catalina ‘black cat’ on the bench. I also have R/C plans for one of these.. Space permitting it my be the next build!
Another trip to my backup model store will be in order in the next couple of days as yet more 1/8″ x 1/8″ strip is required, as well as material for leading and trailing edges of the stabs. The stabilizers are built as two parts with the spars butting up against each other inside the fuselage. Once built and test fitted i think they’ll be bolted against at least one of the fuselage formers.
Also started to look at the mechanism for turning the rudder. The plans have this as a totally enclosed structure within the rudder itself. A control horn will need to be brazed onto a wire and fitted inside the fuselage, and then extended up through the rudder. A similar mechanism will need to be constructed for the elevators.
The fuselage formers are now all glued to the central 3/16″ crutch, and the Tailplane former. Next jobs on the list are to add the ribs to the tailplane section to make it more rigid, then to start cutting and gluing the stringers around the fuselage. I’ve marked the locations of the nose and waist gun positions to ensure i don’t mistakenly glue stringers across these areas. Keel crutch has also been added from the rear former through to the rear of the bomb bay. Also on the list of jobs to complete is to attach the cab roof section to the formers.
Yesterday was the turn of the tailplane to be test fitted to the fuselage. The distinctive B-17 tailplane was formed by splicing 3 pieces of 1/8″ balsa together. It fitted reasonably well first go, with just some minor sandpapering of slots that were slightly tight. With the tail assembly attached this completed the main fuselage. Now we move on to gluing the fuselage together, ensuring it stays as straight as possible.
With all of the fuselage formers and tailplane parts cut the workshop can now fall silent, except for my ramblings and some music. Hopefully more tomorrow as i get the fuselage glued together.
Now have all of the fuselage formers cut out. Just got to notch out where the longerons fit. So thought i’d test fit all the formers to the 3/16″ crutch. Still a lot of work to be done before it can all be glued together permanently. The photo only shows formers 1 thru 14 in place. I’ve still to cut the crutch notches out for the remaining 5 formers before attaching them.
I’ve started thinking about how best to attach the wings to the fuselage for easy transportation. The original plan has the wing as a single piece construction removable by unbolting the wing from the fuselage via the bomb bay.However looking at the diagrams, there seems to be longerons spanning the length of the bomb bay, which would make it impossible to remove the wing. I’m currently thinking of making this a 2 piece wing joined to the fuselage using carbon fibre spars bolted via the bomb bay.
The last couple of days have been spent tracing out and cutting the fuselage formers. The plans called for a mix of 1/8″ ply and 1/8″ balsa to be used. However the widest sheet of balsa i can get anywhere is 4″. This is not wide enough for the formers, I’ve.taken the decision to change this to lite-ply. Although this will make the fuselage slightly heavier it should be pretty negligible. At the current pace I should have all of the formers completed in the next couple of days.
I’ve been thinking about building the fuselage on some form of jig to ensure straightness. My current thoughts are to use some 4″ blocks of wood with spacing controlled by a dowel or metal screw rod. This would maintain squareness of formers, and then just pin the centre crutch to the blocks to keep horizontal squareness. Anyway I’ll continue to play with this idea and post up a picture if it works out.
Made a conscious effort to start on a new build that i have been pondering for a while. I’ve had a copy of the plans for a few months and just finished a trial build of a Lockheed Vega. This build is of a 78″ wingspan B-17G WW2 bomber, named the Bit o’ Lace. The plans were created by Walter Oetzell, but there’s not much information of other builds from these plans on the internet.
Here’s a quick picture of the side view of the aircraft pinned up on the wall currently for inspiration, apologies for the Stuka shadow!!
The plans are missing some key information which the builder needs to take into account. Firstly 3 wing spars that hold the wings to the fuselage have no template on the plans so must be created by the builder. Secondly there is no mention of the required dihedral for the wings, although from a few internet searches this seems to be between 4-6 degrees.
The first task on the list is to start marking out the formers and wing ribs onto Ply and balsa sheets ready to be cut. As i don’t own a cnc machine these will all be cut by hand using an electric scroll saw. I’m using a different method of putting the templates on to the wood this time. Previously i’ve photocopied off the plan and glued the templates to the wood with lo-tack spray glue. I’ve come a cross a couple of issues with this, namely the template not sticking properly, as well as glue overspray. This time im going a little more old school using a set of compasses and tracing paper. We’ll see how successful this is as we go!