Burp
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Span : 45"
Wing section : PW51 modified
Root : 6 3/4"
Tip : 4"
Weight : ?
Wing loading : ?
Length : 23 1/2"
Ballast : Haven't used any yet
Came up with this design after crashing a few Dynamite's, and ending up with a few broken fuselages, seemed a shame to throw them away, too lazy to repair them, what to do? Cut off the boom and make a flying wing plank thing. Will get this one airborne and see how it flies, adjust the tail fin if needed and then bag one with a proper profile to it, should improve its looks too. It looks even better using the new 60" fuse I am building, there is a build thread on both planes here. After a few test flights have found it rather tricky to fly, very twitchy on pitch making it quite a challenge to fly. It seemed at its best in light smooth lift, where I could keep it flying straight and was very impressed with its speed. As the wind picks up, any sort of turbulence has it going off in all directions and gives the thumb a strenuous workout. Not sure where the problem lies, could be the narrow chord, or because I thinned the section, maybe the big dent in the leading edge after hitting a beech tree at full chat while trying some tree line dsing, or a combination of all those things. Finally became disillusioned with it and gave it away to someone who was very keen to sort out its problems, dont think it has flown yet though.
Burp 2
Span : 60"
Wing section : PW51
Root : 8 1/4"
Tip : 4 1/4"
Weight : 32ozs
Wing loading : 12.3ozs sqft
Length : 23 1/2"
Ballast : No room for any really
Thats better, this version flies very nicely. Stock pw section and a wider chord have tamed down the pitching problem and can now fly in a straight line! Probably a little light for general use but a pleasure to fly in light lift and really goes well dsing in light wind, cuts through the shear layer nicely and accelerates well. Has taken its punishment, planted into the hill several times while dsing and have broken the inner nose boat, but made a heavier lay up version and all is well again.
The wing is 3 oz uni carbon and 4 oz fibreglass on the bias with kevlar hinges over a blue foam core. Fuselage is a cut down Hydra fuse with a fin stuck in that I moulded from an old windsurfing fin, have used it on several of my builds now and really like the shape of it.
Felt the need for more speed.....build a heavy version. Fuselage is the same only with a much heavier lay up, and wings were an experiment, used the same core but stuck on 1/16th ply with polyurethane glue, added a 1" wooden leading edge and joined the two halves together with a couple of wooden spars let in from the bottom, then glassed over the centre section with a couple of layers of 6 oz glass on the bias. Cut out the elevons and faced them with a thickened epoxy splurge and covered the whole wing with 175micron laminating film. Cut out the hinge gap on the top surface and smeared some silicone along the hinge line, bit of tape striping on the underside for orientation and it was done. Quite quick and cheap to build which is ideal for dynamic soaring, its quite stiff and flies very fast. It came out at 58ozs and a wing loading of 22.3ozs per sq ft, not a floater but in some decent lift is a great fun plane frontside or down the back.
The laminating film is quick to apply but looks a bit rough, might try wood varnish on the next one, also epoxying the skins on with some uni-fibreglass seems like a good plan, could then cut out the spar slots first with no worries of the glue foaming into them, and would make joining the two halves easier and stronger, adds a bit more weight but the heavier it is the faster it flies, and as long as they are built strong enough they land one way or another!