I made some hydraulic jack extenders from 4×4, 2×4 legs, and plywood gussets. The jacks were Harbor Freight specials. I also laid up some tapered foam parts that fit around the main spar of the aircraft. A slot was cut in the top layers of glass, and the foam was hollowed out to accept the top of the jack. This will keep the plane from sliding off the jacks if it gets pushed.
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My bottle jacks sagged overnight, which made them worthless to keep the plane level. I tossed them and went in favor of mechanical scissor jacks – never sags.
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