Better late than never, I've gotten to a point where I can post a general wing plan and assembly sheet.
The wings have been far more complex for me than any other I've designed and drafted. Part of that is due to my intention to keep the parts count and construction complexity to the lowest level while still producing the most scale interpretation of Jack's original design. Some of the tradeoffs necessary to achieve this are that a small amount of planing will need to be done to fair the spar caps to the rib profiles in order to match those of the original aircraft washout and airfoil sections. However, due to the method of construction and order of assembly, this will be rather simple to achieve and these procedures will be outlined in the build manual that I will begin working on in the week following completion of the fuselage and plan sheets.
One of the features of the model that could not be compromised is the sheer number of wing ribs - 152 in total including the aileron ribs, leading edge intermediate ribs, and root rib doublers. I had debated not using lightning holes in the ribs but Mike and I have decided from a purely aesthetic point of view, that the truss ribs formed by lightening will add much more value than measured simply by the increased cutting time to produce vs. the weight savings achieved.
Additionally, I've incorporated pockets for the ailerons to hinge in to reduce the aerodynamic drag on the full 53" of aileron span on each wing. This alone will provide many benefits in performance and construction has been kept very simple in this feature. Two 1/8" square aileron spar and drag spar members at each side of the hingline will allow for sheeting to be carried out over the hingline of both the wing and aileron propers to make a very small gap. What is not shown on the plan being sent with this email and posted to www.aerosente.com/tom-martins-flightline/ is that the leading side of the aileron hinge spar will have vertical grain balsa webbing applied in the spaces between ribs to make this a very strong spar line with excellent torsional rigidity, while still allowing the wing to flex under normal flight loading. To mitigate the negative effects of the long ailerons, I will also be adding a break at midpoint of the aileron span to allow this flexing to take place without binding of the hinges.
To simplify the construction of a fully tapered spar, I've created the scarf joints in the long fore and aft machined webs and rather than using and infill method of applying the upper and lower aircraft spruce or fir caps, they will be applied after the web sections are complete and filled with the vertical grain balsa cores. in this way the caps can be made slightly oversize and final leveling to the spar shear sections and rib profiles may be done later using the webs and ribs as guides to plane and sand to. In the wing the exact taper ratio for the spar had to be maintained through the radius dihedral bend so that the machined shear would match the rib thickness at each station. In addition, the bend could only take place between the rib outboard of the dive brake door and before that of the inboard aileron chord in order not to interfere with the function or add complexity to the construction of each.
With rib leading and trailing sections cut as separate parts and indexed to slots cut into the shears, wing assembly will proceed quickly and accurately, using leading and trailing edge strips to keep everything parallel and level. The trailing edge core will then be completely enclosed and hidden within the 1/64" plywood sheeting so the wing retains the gusseted flange as in full scale. The leading edge strip will be laminated with infills of light balsa that can easily be sanded to conform to the rib profiles and provide an aid to sheeting as well as a more robust and dent-resistant leading edge when complete.
There is more to come including servo mounting, wing section construction detail drawings and more so please visit the blog for these and more in-depth discussion of the build and previews of the build manual as they become available. And please feel free to email me back with your feedback and questions,
Happy New Year!
All I can say Tom is, WOW! Great work in keeping things right in the building world.
Nice 2-33 kit.
Am finally getting to finishing the 1-1 build. I will send pics when complete.
Jim
Posted by: Jim Weinberg | January 10, 2010 at 07:20 AM