January 2014

Experimenter is a magazine created by EAA for people who build airplanes. We will report on amateur-built aircraft as well as ultralights and other light aircraft.

Issue link: http://experimenter.epubxp.com/i/247918

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Page 15 of 38

LANDINGS… he said. "The spars are aluminum with 3-inch holes in the front one and 2-inch holes in the rear spar. Currently there are 13 full ribs with no short leading edge ribs, which are usually used to support a leading edge. We can get by without the nose ribs because our leading edge is carbon fiber and is so stif that it doesn't need the support. The fabric is pop-riveted to each rib with no rib stitching. The tip is currently a short wood bow, and normal drag, anti-drag wires are used throughout." It should be mentioned that the carbon-fiber leading edge has two rows of 3-inch lightening holes on the lower side that are covered by the fabric. A good indication that someone is a hardcore weight freak is when he cuts lightening holes in carbon fiber, which is already feather light! We wouldn't be surprised to find that Frank's fat tires are filled with helium. What appear to be fixed slats on the leading edges of the wings, and which certainly complicated the wing structure, are actually air pressure–activated slats. Frank said, "The slats close with speed and open once the angle of attack is increased at slower speeds. We tested several opening gaps and found that a 3-inch rear gap allowed good transfer of air through the opening without frontal bunching of air." And speaking of details, note that Frank has vortex generators (VGs) on the inside of the slot that is formed, when the slats are out. He explained, "The VGs were very efective at preventing an early stall before the slats were installed. Because of the boundary layer improvement without slats, we left the VGs in place to help stabilize the compressed slat air. While testing with slats extended, if one side had no VGs, it would stall; however, the side with VGs would not." It's also worth noting that carbon fiber is used in a lot of unexpected applications. For instance, the brackets that hold the slats in place are constructed from seven layers of carbon, rather than being formed or milled aluminum. They also used carbon fiber for the window and doorframes as well as miscellaneous small covers. Obviously, Frank thinks every ounce counts, which has paid of. The flaps that he is flying now are fairly "normal" hinged units, but he said they may evolve into being double-slotted Fowler types. However, he added, "They must be light first, As this issue going to "press, we learned that the Lil' Cub " was destroyed in a hangar fire in late December. However, we felt the uniqueness of this aircraft deserved that its story still be told. In better news, one of the world's most unique aviation competitions, Valdez Fly-In & Air Show, will be re-created at EAA AirVenture Oshkosh 2014. The airplanes that compete at that event in May each year will visit Oshkosh. Along with flying demonstrations during AirVenture's daily afternoon air show July 28-30, the Valdez STOL aircraft will stage a "fun flying" demonstration from the grass ultralight runway on Friday evening, August 1. The aircraft also will be on display in special parking areas and on the main showcase ramp at Oshkosh, with pilots and builders part of forums and evening programs throughout the week. 16 Vol.3 No.1 / January 2014 Photography by Brady Lane

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