This weekend saw a bit of progress on three fronts, two old and one new. The old things were the ASK21 tools. I finished welding five examples, so they're done except for the cross-handle and painting. I also finished cutting the right side flaperon hinge radius for the inboard flaperon section. So now I've finished the hinge radii for both of the right wing control surface plugs.
Next weekend I'll probably be sanding and finishing the flaperon hinge radii and also making and boxing up some legacy HP parts.
The new thing I did was to weld up an arm gizmo for dimpling rivet holes in aluminum skins. You can get these things in the catalogs for $140 or so, but I saw no call for spending cash money on one.
Here's the right inboard flaperon plug chucked up in Radius Maximus. As you can see, the machine envelope addresses less than a third of the workpiece. I ended up shifting the workpiece three times to cover the whole thing. You can also see the popsicle sticks that we used to hot glue the radius blank onto the flaperon plug. At this stage the popsicle sticks are redundant, since I've glued the blank onto the plug using epoxy and micro. I chipped the sticks off after this photo and before starting the cutting operation.
Another view of the flaperon plug and Radius Maximus, showing the hinging features that the flaperon plug pivots on.
Here you see the "before and after" view where the radius is being cut. In the foreground you see the cut radius, and beyond that the raw radius area blank. After getting the flaperon plug chucked and indexed, the cutting operation goes like this: crank the translation drive 2 turns (1/8"), pivot the flaperon plug through one full deflection (about 60 degrees between stops), and repeat.
Here's the dimpling arm I built. In this photo I'm reaming the punch bore to 0.500".
Homebuilt aviation is not for folks who don't try things at home.
page updated 3 June 2007 all text and graphics copyright (c) 2007 HP Aircraft,
LLC