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Changes:
Note: Red colored changes are the most critical Replaced Spar Fitting Bolts with Tapered Pins - Chris Bobka and Dale Johnson were the advisers - Avoids the wear-and-tear of assembly/disassembly using precision bolts - Assembly is easier - Required slightly larger hole - Edge distances verified using Canadian guidelines Outer Spar Fittings made from Bar stock rather than plate - Bar material is 63,000 vs. 64,000 for the plate - Performed strength calculations - Note: Fittings are double shear. Thus, the outer fittings two fittings sharing the load. Therefore, they only carry half the load (i.e.: ½ the load for each) - Tested strength of material by destructive test of sample, see Strength Testing Modified Shape of Nose Rib: - Revised shape does not change the external shape of the airfoil - Simplified the effort the cut out the part. - Eliminate poor edge tolerance for 4 rivets - Produces a slightly stiffer part. Rear Vertical on Rib made wider on ribs at Spar Fitting Station: - Solves rivet edge distance problem - Eliminates the need for a gusset Changed Order of Skin Installation: - Plans call for the Bottom Skin to be installed first. - I installed the Nose Skin first which enabled me to build a sturdy/accurate D-Cell. Rounded end of 40 inch inner spar caps: - Made slightly longer to avoid rivet hole, rounding avoids abrupt change in strength Rib Stiffeners are slightly longer with angled end: - Improves rivet edge distance [ Return to Home Page ] |
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Future Changes:
Move
wing approximately 2 inches to the rear:- At my weight, several builders have advised to move the wing 2 inches to the rear. - Impact on flight dynamics will be reviewed with Chris Bobka (longer nose, shorter tail) - A tail heavy aircraft can be dangerous in a spin. … counter consideration: - With the center of mass more forward from the landing gear, landings may be harder (for a tail dragger) - Building impact should be minimal: slots for spars be relocated, a few side angles need to be longer, radius of rear spar bulkhead needs to be reduced slightly, and joy-stick to aileron push-rods will have to be longer. - Seat bottom may be impacted Engine Choice: ... First choice was 27 hsp for longer range ... per Dale Johnson's recommendation. - It is my guess that with any size engine, the max speed of 55 knots will be reached (assuming correct prop). - I now intend to use a 32 hsp one-half Volkswagen - 32 hsp is 4 pounds lighter than the 27 hsp engine (I assume from boring the cylinders). Use formed ribs in center section: - I chose built-up ribs for the weight savings ... and I save money. Also, they were fun to build. - It turns out that not very much weight is saved (1 pound?) - The formed ribs have very nice enlarged lightening holes which would make it easier to reach into the wing. - Conversely ... Rib doublers block most of the holes ... aaagh! |