05/03/2004 (3 hours):
Tonight I laid out and glued up the pieces for the fuselage bottom. It actually took me six pieces, not three, because I only had two full pieces left over from making the sides. I guess I didn't lay the sides out very efficiently... Whenever there is any appreciable excess always read ahead to see HOW it is used. Not a big deal, stitching foam together with 5-minute epoxy is old hat now.
I wish I had made one of my work tables 8' rather than having both be 6'. I don't have enough room to set them both up AND the fuselage (I figured I'd have them in the garage by now). It doesn't appear this will be a problem much longer, since most of the rest of the steps appear to be done either directly on the fuselage (e.g. head rests) or on BOTH tables (e.g. wings and spar). But, since the plans have you lay up the bottom foam pieces off the fuselage on little wood forms (say hello to my leetle frame), this last step would work best on an 8' table (it's about a 7-1/2' section).
I did this a little differently. I laid a straight edge across the top, and measured down at several points along each side. I made a spacer for each spot double the height of each measurement, so my fuselage has now become my work table. It works really well provided you're careful to give it some horizontal stiffeners so the foam doesn't droop in the center. There are three big advantages to doing it this way:
1. The foam is pretty fragile, and it's easy to damage it while transferring it back and forth. With this arrangement, you never move it (except to flip it over).
2. I used brads instead of Bondo so there are no holes to fill when I'm done, unlike the sides, which are now full of divots.
3. "...crawl underneath and mark..." You've gotta be kidding me, right? Ahem, my fuse is on pivots! I just rotated the fuselage to 90 degrees to trace, then rotated it back. 60 seconds and no aching knees.
05/04/2004 (6 hours):
Cutting the foam was an easy enough step, just a bit of work with a Sharpie and a 2" utility knife. Before I did this I had to do a bit of trimming to clean up some flox and epoxy drips that had made their way to the bottom of the fuse. I'll have to be more careful in the future to catch drips with plastic or something else.
I got a little bit ahead of myself cutting out the landing brake. I was using a utility knife, not a saber saw, and my blade dulled faster than I expected. Always check your blade before cutting foam, especially PVC! It made a ragged cut in some areas. The second picture below shows a rough cut made with a dull blade, and the third shows a smooth cut (I bet you can't even see it) made with a sharp blade. I'm sure it will be OK since even after cleaning up the cut it's still a smaller kerf than the recommended saber saw would have made, but still.
I did encounter one fairly serious problem, though. I ran out of 3/4" Last-A-Foam to make the spacers with. When I asked around on the list, it seems this is not exactly unusual; many people have filled in with other foam types. The foam type I have the most of is PVC. Nat was kind enough to respond:
Dear Chad, You can certainly substitute PVC for Last a foam. PVC is better, but a little more expensive. That is why I specified Last a foam. Regards, Nat
So, straight from The Man. I'm filling with PVC. He's right, there's about a $10 price difference per sheet, but I don't really mind. I'd rather do this than wait a week for another sheet to arrive. Aircraft Spruce hasn't exactly been zippy filling my most recent order. I placed it last week and it hasn't even SHIPPED yet.
Anyway, today I made the 3/4" spacers that thicken the fuselage bottom. This was a real pain because of all of the pieces I was stitching together, and because the PVC and Last-A-Foam didn't sand at the same rate.
05/05/04 (3.5 hours so far):
I have now micro'd the spacers in place, and have begun making fillets with stiff micro to make smoother transitions. This step uses BID (unlike the sides) so I probably won't have any issues getting it to lay down without air bubbles, but I'm not taking any chances. It was too much of a pain to fix them on the sides.
Lucubration
http://old.lucubration.com/cozy-mkiv/cozy-chapter-log.html?chap=6[6/19/2013 2:03:56 PM] Using stiff micro is an education in working quickly. When using all Slow hardener, I get hours of "pot life" and nearly a day to cure for normal epoxy usage. But with micro and its insulating properties, I got barely 15 minutes of pot life out of this batch, and that's with barely an inch of it in the bottom of the cup. The more micro you use the faster its insulating properties can cause it to exotherm, and the stiff (thick toothpaste) consistency I was using is about as fast as it gets. I've learned that the best thing to do is just get it out of the cup as quickly as possible, even if you're dumping on 10 times what you need in a certain area. You can always take the excess back off, and keeping it spread out keeps it cool.
05/06/04:
I got absolutely nothing done tonight because my Zaurus (for Galileo, see link above) came and I was playing with it. In fact, I'm writing this entry with it!
05/07/04 (5 hours):
Six cups of micro. Eleven cups of epoxy. Five hours. One layup. Phew. I'll be VERY glad when this chapter is over, but it's almost there! I made an executive decision to make the "scuff" layer of BID in a separate layup (probably at the same time that I do the BID tapes so the tapes hide the edges of the scuff layer).
I'll also never buy from Aircraft Spruce again. I placed my very first order with Wicks to be sure I got exactly what I needed (since I wouldn't have known the difference). This time around I agreed to give Spruce a try, so two weeks ago I placed orders with both Wicks and Spruce (the Wicks items were things Spruce was out of at the time). A few days later I got my Wicks items, just like my January order. The same day, I got a call from Spruce asking me how to ship a certain item. Since then, every other day or so I get another call asking how to ship one more thing. Jeez, I'm just about out of epoxy, micro, and fiberglass cloth. I'm glad I ordered a little extra with my first Wicks order, or I'd be stalled already. This order was no more complex than my Wicks order in January, but somehow it is taking Spruce a lot more effort to get it out the door.
05/08/04 (1 hour):
It doesn't seem like a big deal, but today Nicole helped me attach the bottom to the fuse. It IS a big deal - when you complete this step, you have a "tub" even though there's still work left to do in the chapter, such as making flox fillets, doing the BID tapes, etc. I weighted the bottom down with a lot of objects - I ran out of bricks so I started using tools and even a 24-pack of soda. (Hey, at 12 fl. oz. per can that's 2.25 gallons of soda, or almost 14 pounds!)
The skin is relatively stiff despite only having one side glassed, so I'm glad I did a good job with the way I supported it above the fuselage for glassing because if I'd done it wrong it would have been very difficult to correct with weights alone. As it was, despite all the bricks I had to help out by squeezing with my hands. I had used a ziploc full of flox to squeeze out a bead onto the fuse, and despite all the weight it wasn't compressing the flox! Flox is stiff even BEFORE it cures!
Anyway, despite Elliott crying for Nicole's attention we got it done and I'm happy to have this off my plate. A few more steps and the chapter is done.
05/17/04 (1 hour):
I'm changing employers so I had a short hiatus with all the fuss going on. I also screwed up mounting the bottom skin, so I got frustrated and let the project stall. It's not the kind of thing where you say "cut it off and fix the error" - I actually made several of the foam pieces too large, so I'd have to almost remake the entire bottom skin. The botch isn't visible from the outside. The issue is that the foam pieces the bulkheads and longerons sit on are too large, mainly along the sides and under the front seatback.
Rather than scrapping the whole thing, I'm using my Fein, a utility knife, and other tools to cut out the problem sections. Then I'll micro those areas, and when I BID tape I'll use two extra layers to simulate the BID that's on the bottom skin. This should produce a joint that's just as strong, if not stronger, than what is already there, so I'm not really worried, just annoyed. I'll post pictures when I get a chance.
05/23/04 (4.5 hours):
Almost done! I've fixed my mistakes in laying out the foam spacers by using my Fein to make flat cuts into the spacers following the surfaces of the seat back and fuse bottom. The two now meet in a straight angle with no more bump. This did involve cutting the BID that wraps over the edge here, but I solved that with the usual flox trick, including cutting interior flox-corner grooves. I also added two extra layers of BID to the BID tapes to make up for the missing BID in those layers. I then spent several hours making and installing BID tapes along all of the joints forward of the seat back. (I knew I wouldn't have time to do the rear as well in one night - it's already almost 2am.) There are a surprising number of them here - seat back to floor, floor to center brace/duct, floor to side (aft of instrument panel), floor to instrument panel (aft), floor to instrument panel (forward), and floor to side (forward of instrument panel). There are also two of each location, left side and right, for a total of 12 tapes just in the area forward of the seat back. To help the tapes conform better I did the forward side of the instrument panel with two tapes even though one would have technically worked - it doesn't add any extra strength because the holes from the heat Lucubration
http://old.lucubration.com/cozy-mkiv/cozy-chapter-log.html?chap=6[6/19/2013 2:03:56 PM] duct basically eliminate that possibility, and it would have been much more difficult to keep out air bubbles. Another few hours doing the area aft of the seat back and Chapter 6 is history!
05/25/04:
And Chapter 6 is done! Phew, that was really a stinker. Getting the BID tapes to lay into the acute angle behind the seatback was a chore, and there are many feet of tapes to install in the rear. But that, as they say, is that.