Because this particular Glasair was originally delivered to it's first owner sometime in 1983, the current models include a lot of changes to the airframe. Some of these changes made the aircraft larger, some added control features and some were for longevity of certain components. The two drawings below show the differences in the size of the original Glasair I (left) and the current Super II (right) airframes. You can click on each plane for a larger version:
I have both of the drawings available in .dxf and Deltacad .dc format. Right-click these links and select "save link as" or "save target as" to download them: Glasair I.dxf, Glasair I.dc, Super II.dxf, Super II.dc
The Glasair airframe was upgraded by the factory in three stages. The Glasair II added 1.5" to the height of the canopy and 3" to the width of the passenger area. The Glasair II-S added 14" fuselage length behind the pilot. The Super II added another 6" to the area ahead of the windshield and moved the wing aft 1.5". The Super II also increased the horizontal by 30%. I rescaled the original Super II (right) drawing with these changes to come up with the Glasair I (left) drawing. I also decreased the diameter of the prop to match my 72" Quinti on the Glasair I.
My design changes:
I'm generally a believer in sticking with the design when building a kit plane. Even so, some exceptions have come up while building my plane. The mechanical changes I decided to implement focused on safety and longevity of the airframe.
TD to FT Conversion:
I converted #446 from a tail wheel to a fixed tricycle gear. Call me a weenie, I just know my flying skills.
I replaced my stock design, fiberglass, header tank with a custom aluminum tank made by Boyd Welding.
Electric Flap Install:
The idea of having to put all that force and thought into pull on a handle during critical phases of flight made me do it.
Newer Style Gull Wing Doors:
A larger opening and a better sealing door were the priorities here.
Newer Style Elevator Trim:
I designed a new elevator bell crank for the trim to attach to.
Wing Root Fairings:
All I can say is "Safety wire!?", no way.
Hinge Pin Retainers:
Again "Safety wire!?".
Weight and Balance:
So, how did all this affect my weight and balance?.
Wing Tank End Cover:
The first airframe change I made was to position the fuel baffles in the wing in the same manner as the newer wing design. This added a small amount of range and basically amounted to the outer most rib or end cap being positioned at the wing tip rather than a foot or so from the end.
While still on the wing, I capped the d-rib. This is essentially created an upper cap similar to the main spar, but only consists of a 4 layer laminate. First I made a pre-cured 2-layer laminate 2" wide and the length of the d-rib. After shaping the d-rib to match the upper wing skin, I trimmed an extra 1/16" off of the top of the d-rib to allow room for this laminate. I traced the top contour of the d-rib onto a piece of 2x4 and cut it out on the band saw. Using milled fiber I laid the 2-layer pre-cured piece centered over the d-rib and placed the matched contoured edge of the 2x4 on top of it. I added two bricks as weight and a bungee cord to hold it all in place. After the milled fiber cured, I applied micro-balloons to create a radius from the sides of the d-rib to the underside of the cap. Then I applied a 2-layer laminate over this radius 1" onto the d-rib and cap. This eliminated the lay-ups required after wing closing.
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