This update shows the plug for the HP-24 forward fuselage under construction. The plug is just a part of the same shape as we're trying to duplicate with the actual forward fuselage. Later, we'll use the plug to make the molds for the production forward fuselage parts. We'll also use the plug to make a mold to make another plug that we'll use to form the canopy for the HP-24.
Our plug started life as a set of three-view drawings on a computer. Using those drawings, we lofted cross-sections for 42 different fuselage stations. Then, we handed the files for those cross-sections over to a CNC shop, where they were cut out of 1/8" double-tempered masonite. After we got the templates, we glued them to ovals of 3" urethane foam, and stacked them onto a 6" diameter aluminum tube. The next step is to sand the foam down to fair with the masonite templates, and then apply layers of fiberglass and filler to make the surfaces smooth and wave-free.
A general side view of the plug under construction. The bottom half is already rough-sanded, but the top is still in the wedding-cake shape of the raw stack of disks.
A three-quarter view of same. You can see the RS-15 tailboom that we're using as a stacking spindle for the foam and masonite.
Aft looking forward over the top of the plug. You can see the oval cross-section where the semi-monocoque aft fuselage will connect.
Same, other side. The dark line near the point of max thickness is where I messed up one of the datasets for the CNC-cut templates. I see some microballoons in my future...
Three-quarter view, this time with the plug dot-commed (that is, belly-up).
Fore-quarter view of inverted plug. Here you can sort of get a sense for the broad belly of this thing.
Closeup of previous view. The faint lateral lines mark the locations of the Masonite templates.
Looking aft over the inverted plug. The flattened belly is particularly pronounced in this photo. However, this is sort of a 'privileged' perspective. The only people who are going to see this a lot are the people who you've out-thermalled, and the guy who fixes your gear-up boo-boos.
Plugger extrodinaire Steve Smith..
Steve and the big pink armadillo.
Sanding the corners off of the wedding cake.
The 2 lb/ft^3 urethane foam sands really easily. Only a few minutes have passed since the scene in the previous photo.
Twenty minutes later, almost all the wedding cake edges are gone.
Sanding the sides. Here, the difference between the rounded crown and the flattened keep are most evident.
Forward half, right-side-up, right side shown. This is the area where we'll be pulling the mold that we'll be using to make a canopy plug.
Another of those views that show the unique cross-section.
Another shot of the belly of the beast. The faint longitudinal line is where we sawed a keel slot for alignment purposes.
Same, other side.
Steve's cat Chester, who prowls the furniture summits in search of dust balls and flying insects.
page updated 04/20/01 all text and graphics copyright (c) 2001 HP Aircraft, LLC