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Old Dec 18, 2014, 12:59 PM
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Joined Feb 2013
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Build Log
1.8m pw51 plank 4 servo

This winter decided to experiment with glass fibre and lost foam construction. Had a trial go with a lost foam fuselage. Interest in planks from last winters build at this link - balsa construction of 1.5 and 2.4 metre planks.

http://www.rcgroups.com/forums/showthread.php?t=1916599

going to keep with the four servo wing construction. Plan to use blue craft foam as wing cores and then glass on the outside. Wing to have carbon fibre tube spar and tow spars. I have blue foam in 10 mm thick sheets so will glue several sheets together to make up the thickness. Span to be 1.8 metres, with MAC around 250 mm, root chord 290mm. Ailerons/elevons 60 mm.
For the fuselage going with a pw51 outline, and using the blue foam in a lost foam fuselage method. Tail fin - eta shaped and 8% wing area.

sketches of the plank are attached.
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Old Yesterday, 04:57 AM
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Joined Feb 2013
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wing panel - 3 layers of 10 mm foam stuck together with pva adhesive. channels sanded for carbon fibre spar and servo wires. airfoils shape sanded using Mark Drela's method - marked on intermediate bevel points at selected locations then joined the dots to form sanding lines. Craft foam shapes sanded with 120 grit then 320 grit.
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Old Yesterday, 08:38 AM
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in preparing the foam for laying glass fibre, the foam was absorbing a certain amount of laminating resin. a little discussion on the composite forum to see if it should be sealed. link is here
http://www.rcgroups.com/forums/showthread.php?t=2296124
tested a few samples, and applying pva adhesive followed by a light sanding reduced the absorption, and improved the sanded foam finish.
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Old Yesterday, 11:33 PM
skumgummi dave
Gresham, OR.
Joined Mar 2004
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Old Today, 12:14 PM
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Joined Feb 2013
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stuck four sheets of 10 mm foam together and cut then sanded to rough shape (pw 51 airfoil shape - modified on rear to accommodate tail fin. Previous attempt at lost foam fuselage had tail and fuselage joined. Struggled to remove all the foam residue with a one piece construction, so thought i would go with a fuselage and separate tail fin. fuselage is 40 mm at its widest. Once achieved a reasonable shape i parcel taped the centre section in preparation for making canopy hatch and cowl to cover the wing. Might go with a single canopy hatch that extends from the front from the reciever/battery access over the wing seating area to the tail fin. not decided as yet.
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