 Jon
Matcho's Homebuilt Aeroplane Project |
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Chapter 4 |
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This is the first real building chapter, broken down into 4 steps (one for each major part):
May 29, 2004 - I began the process of measuring twice before cutting once. I ended up spending an excessive amount of time comparing the full-size drawings to the originals (which are only half the picture -- you need to create mirror images to produce full-sized templates). Since I might have been the first builder to purchase the full sized drawings, I wasn't going to take any chances. I got distracted with finding the full-sized drawings of the Instrument Panel bulkhead were 1/8" larger left-to-right, and 0.04375" larger top-to-bottom than their original-sized counterparts. After several moments of head scratching, I concluded that these minor differences amounted to nothing critical, and decided to move on. Some of the decisions made to produce the full-size plans turn out to be quite good, and likely better than what I would have produced with tracing paper anyway.
I pulled the necessary materials from their shipping containers. After another hour of head scratching, I convinced myself that I was looking at the right shade of blue foam. May 30, 2004 - I began to think about widening the fuselage a couple of inches. Why? Because it would be bigger. Bigger = better. With this in mind to finalize, I joined two 2' x 4' sheets of blue foam and left for a Memorial Day picnic. May 31, 2004 - I re-read all the info I could find on widening the fuselage. I apparently overlooked the increased drag factor, which I found not at all appealing. I'd rather be Fast and Cozy than Slow and Comfy. In addition, there are CG issues to reckon with. Finally, with the help of some "gentle persuasion" from Marc Zeitlin, I rejected the widening idea and cut a per-plans 42" x 28.8" piece of blue foam. At this point I found that neither the full-sized templates nor the originals provide all templates for the seatback -- you have to make some mirror images. So I just traced the back sides of what I cut from the full-sized prints. How ironic -- pay extra $ to avoid tracing, and I still end up tracing.
I micro'd, glassed, epoxied, and did everything as I thought I would, but... I made 2 mistakes:
I quickly pulled the plastic off and re-stippled the trouble areas back into shape. No big deal in terms of air bubbles, just some movement of epoxy underneath. 30 minutes later, browsing my work while washing up, I discovered that when
pulling the plastic off it also pulled the 2nd corner piece of glass off.
Back on with the gloves, mix more epoxy, glass, and all was back to normal there
-- better too, since now I put this piece of UNI butt up against the
other. I might be qualified to make surf boards now, or at least boogie boards. August 11-12, 2004 - I measured and rough-cut the notch holes for the heat duct and whatever else is supposed to go through the bottom-middle of the seatback. The next evening I cut the 45º notch and fine sanded. I'm holding off from cutting the map pocket until figuring out how to maximize that space (in other words, "no rush" on that).
June 5, 2004 to July 3, 2004 - In hindsight, these are easy parts, but turned out to be time consuming because I wasn't using the right tools. I was cutting the foam with a Dremel, as well as the glass. I was also chasing the ever elusive 'chewing gum stage', which I now consider a complete waste of time. Jerry Schneider told me how good the Fein was, but it was when John DiStefano stopped by to show me the tool in action that I was immediately sold.
There were two options for cutting the smaller bulkhead, which dictates the shape over the nose. One option is slightly taller than the other, designed to give the nose a slightly more rounded appearance. However, I thought that this would obstruct the forward view slightly, so I chose the smaller dimension. In hindsight, I wish I went with the taller dimension as it is so very easy to cut it down later using the Fein and long Permagrit sanding block. I still may choose to make the taller version, or go crazy and make a slightly longer nose. August 7, 2004 - I really wanted to find plans for an aluminum panel insert, as I'm certain that the day after I cut my panel, I'll want to move one of the holes around. Having a removable panel would allow wiring and maintenance on a test bench, so this is one bridge I know I'm going to have to cross. In the meantime I'm building the panel per plans, expecting to cut it up later. I cut out the template and traced to 2 pieces of foam. Looking at the result, I couldn't help but noticing how very small the leg holes are in the instrument panel. I've had the joy of being in Marc Zeitlin's Cozy for hours and had no issues, but I just couldn't get over how tight they looked. August 8, 2004 - I cut the foam with... you know it, the Fein MultiMaster. I used a Dremel cut-off wheel for all the other bulkheads requiring the high density foam, and what a stinky and dusty mess. The Fein made this a non event, leaving minor sanding and filing for the fine details. You can also see that I've picked up a helper.
August 9-10, 2004 - As you can see from the prior picture of the instrument panel foam, it's made from 2 pieces, where the plans call for using 5. This would have left thin strips available to make the 1" reinforcing ribs, so needing to make these strips out of 4 spare pieces is my bonehead move for the week.
The great thing about working with composites is that it's
hard to make mistakes that you cannot recover from. I can't wait until I
get to make the big ones.
August 27-29, 2004 - I did the 3 layups on each side of the instrument panel at once. Knowing I'd be able to use the low pressure vacuum bagging technique, I was confident I wouldn't have a problem and did not. Seeing some minor dryness in the previous layup, I made a point to wet-out the peel ply, which yielded minor improvements (the prior part wasn't really that bad). Trimming the glass, sanding, and filing the detailed edges was a workout. February 20, 2006 - A crew from my EAA Chapter #1333 stopped over to take a look at my project, and were promptly put to work on finishing my IP ribs.
February 22, 2006 - I sanded my helper's work clean and is ready for the plies that make up the lips. Step 4 - Landing Gear Bulkheads July 9, 2004 to August 4, 2004 - The plans call for 22 layers of BID to produce a 1/4" piece of strong hardpoint material. This is a tedious and time-consuming process, so you may want to consider finding some 'G10' material, or just accept that you're working for $0.15 per hour. Regardless, I found the result fascinating -- a super-strong piece of thick fiberglass that I actually made.
I cut the bulk material out with the Fein, and borrowed my friend Gene's bandsaw to cut the details. I probably owe him a new blade. Here's how I transferred the templates to the foam:
August 5, 2004 - Here's where I'm at with my landing gear bulkheads. I moved from Fein sanding to fine sanding (if you can call it that with a 60-grit tungsten carbide sanding block). The marks on the middle piece on the right are from lightly sanding some of the waviness from my 'gravity bagging technique' (not to be confused with 'pressure bagging', and regardless, both are seriously inferior to the technique that the Cozy Girrrls have pioneered).
I still have to bevel some edges here, and figure out which sides are going to be fore and aft facing. August 7, 2004 - After my 3rd head-scratching session with the drawings for the cross section for how the edges are to be angled on the top bulkhead in the previous picture, I set my router and went at the edges for some perfect 45 degree angle cuts. At least that was my intention. Turned out that the glass would have none of it, and started eating the router bit!
After that, I just drew some lines and brought out the Fein for the rough cut, and then sanded to perfection with my Perma-Grit sanding blocks. August 26-27, 2004 - One of the three LG bulkheads calls for an extra ply of UNI than the others, which I missed when I did all three at once. I waited on doing this layup until I completed the setup of my low pressure vacuum bagging "rig".
I'm done with the LG bulkheads aside from some additional layups I need to do as part of fuselage assembly. October 10, 2006 - I forgot the 3+8 plies on both sides of the aft LG bulkhead. I was test fitting and measuring for fuselage assembly in Chapter 6 when some measurements were just not adding up. After checking the Cozy mailing list search engine, I found that Bill Kastenholz had the same problem 10 years ago. Turns out that we both forgot to put the 3+8 additional plies described in Chapter 4 Step 4.
I wanted to wait on the firewall until I saw how my modified (wider) sides would come out. I'm going to get measurements from my temporary firewall before I build the permanent firewall. |
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