The German Junkers J.I armoured fuselage ground-attack sesquiplane of 1917 used a Hugo Junkers-designed multi-tube network of several tubular wing spars, placed just under the corrugated duralumin wing covering and with each tubular spar connected to the adjacent one with a space frame of triangulated duralumin strips - usually in the manner of a Warren truss layout - riveted onto the spars, resulting in a substantial increase in structural strength at a time when most other aircraft designs were built almost completely with wood-structure wings. Fatigue of metal wing spars has been an identified causal factor in aviation accidents, especially in older aircraft as was the case with Chalk's Ocean Airways Flight 101. Larger aircraft using this method of spar construction may have the spar caps sealed to provide integral fuel tanks. Metal spars īasic metal-sparred wing using a honeycomb 'D' box leading edgeĪ typical metal spar in a general aviation aircraft usually consists of a sheet aluminium spar web, with "L"- or "T"-shaped spar caps being welded or riveted to the top and bottom of the sheet to prevent buckling under applied loads. A number of enthusiasts build "replica" Spitfires that will actually fly using a variety of engines relative to the size of the aircraft. These spars are laminated usually from spruce or douglas fir (by clamping and glueing). Wood wing spars of multipiece construction usually consist of upper and lower members, called spar caps, and vertical sheet wood members, known as shear webs or more simply webs, that span the distance between the spar caps.Įven in modern times, "homebuilt replica aircraft" such as the replica Spitfires use laminated wooden spars. A disadvantage of the wooden spar is the deteriorating effect that atmospheric conditions, both dry and wet, and biological threats such as wood-boring insect infestation and fungal attack can have on the component consequently regular inspections are often mandated to maintain airworthiness. Wooden spars are still being used in light aircraft such as the Robin DR400 and its relatives. Several different wooden spar types have been used and experimented with such as spars that are box-section in form and laminated spars laid up in a jig, and compression glued to retain the wing dihedral. Materials and construction Wooden construction Įarly aircraft used spars often carved from solid spruce or ash. Many of these loads are reversed abruptly in flight with an aircraft such as the Extra 300 when performing extreme aerobatic manoeuvers the spars of these aircraft are designed to safely withstand great load factors. The "D" box construction is beneficial to reduce wing twisting. Further twisting loads are induced by changes of thrust settings to underwing-mounted engines. Chordwise twisting loads due to aerodynamic effects at high airspeeds often associated with washout, and the use of ailerons resulting in control reversal.Drag loads dependent on airspeed and inertia.Downward bending loads while stationary on the ground due to the weight of the structure, fuel carried in the wings, and wing-mounted engines if used.These forces are often offset by carrying fuel in the wings or employing wing-tip-mounted fuel tanks the Cessna 310 is an example of this design feature. Upward bending loads resulting from the wing lift force that supports the fuselage in flight.A black Sparkle Wing RS2 is also a good drowned Trico imitation when trout are keying on sunken spinners.Some of the forces acting on a wing spar are: During the peak of the hatch, when trout may key on emergers, a this fly is a great candidate for the greased leader technique. As the hatch intensifies you should fish less weight allowing the fly to drift mid-column. During non-hatch periods, or during the initial stage of a hatch you can fish the Sparkle Wing RS2 off a larger attractor nymph near the bottom. It is an effective mayfly imitation from the bottom to the top. We recommend changing your attractor based on the season but routinely keep the fly as a dropper due to its versatility. The Sparkle Wing RS2 performs well in a variety of conditions. Although the original pattern was gray, you can easily change the color of the dubbing to match just about any mayfly emergence. Another option is to use a clump of gray rooster hackle one shank length long. Churchill uses a few fibers of elk for the tail. Churchhill substitutes Pearl Braid for the saddle-hackle webbing (for the emerging wing) used in the original design. Churchill’s pattern is a variation of the original RS2 created by Rim Chung nearly 4 decades ago. The Sparkle Wing RS2 was invented by professional fly tier Bob Churchill.
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