Chapter 8 - Head rests, Seat Belts, Heat Duct

Head Rests & Shoulder Support

While waiting for my Chap 8 supplies from Wicks, I found enough spare foam to make these items. I've been pondering the big triangular headrest design for a while. Perhaps this is something I'd like to personalize. Haven't you learned yet Slade? Build it and it will fly. I built the headrests per plans. I just didnt install them. (see my chapter on Modifications for further thoughts on this). Couldn't figure out why one headrest had no back. Finally, looking forward in the plans I noticed how the canopy has structural supports which just happen to be the same shape as the headrests. I read in the archives that the headrest design is 3/4 inches too big and it should be cut down (apparantly confirmed by Nat). Mine do look a bit tall, but I'll hold off glassing the outside of headrests till I do the canopy installation, then cut them to size as needed. I'm planning to install my headset jacks in the shoulder support by the left shoulder of the pilot and right shoulder of the copilot. I'll need to run the wires now, before glassing the shoulder support in place. I think the wires can run down the seat brace to the center conduit, then forward from there to the panel. While I'm at it I'll run a couple of wires for a map light. I ordered the Chap 22 wire in advance so I can do wiring as I get to it. Called RST to ask which wire to use for the headset audio. They say use RG174 coax for the mike and 24g for the rest. Can't get RG174 locally. Decide to put the jacks in the armrests later rather than hold up progress. Probably a better place anyway. The wires will be shorter and run right into the electrical conduit. [Later note: As I prepare for FAA inspection 5 years later the big ugly headrests are still stored in my laundry room.]

Seat Belts

The hard points went well. I have LOTS of little BID triangles left over which are now getting used up on things like this. Did the layup on wax paper, then transferred it to the plane. [Later note: forget the wax paper. 4 mil plastic from Home Depot is the stuff. Once I discovered how well the plastic worked I threw out my wax paper and never missed it]. Ordered one harness from Wicks so I can see how it fits. I'll get the others later. Made the angle brackets out of 1 1/2 aluminum and floxed them to the hard points. I read the archives about recessing the step and took my belt sander to the left side (not yet glassed). After the side was glassed I floxed the step in place holding it with tape till cured. I drilled the holes for the step from the outside and the holes for the seat belt attachements from the inside. The six AN825-8R16 1 inch bolts are missing from Wick's Chapter 8 parts list. Once I realized they were missing I called Wicks. Wicks say they are not available anymore. I ordered them from AC Spruce (who also say they're being discontinued). When they came I found they were 1/4 inch too short. I need 1 1/4 bolts. I've read that others had the same problem. I emailed to Nat about this telling him that the bolts reach just to the underside of the alum bracket. Nat said to countersink until I have enough threads to put the nuts on.

Canopy Hinges

The 20 inch piece of hinge was invoiced, but was not in my box from Wicks. I called and they sent it immediately. It arrived just in time for fitting. See Chapter 18 for details, then see Chapter 27 for why I eventually replaced the hinges and how I had to repaint the canopy top because of the embeded nuts turning in the micro]

Heat Duct

Since my Chap 8 supplies had not come (I was late ordering them) I found some scrap 1/4 foam and pieced together the heat duct with 5min epoxy. The "transition piece" was interesting. Carved the foam in a few minutes. Wrapped box tape (sticky side up) using a spiral. The plans say "as best you can". I figured this was a subtle warning from Nat that the task is practically impossible. The spiral approach worked fine. You can make almost anything with these techniques. [Later note: When it came time to install my fuel header tank I found that the heat duct needed to be lowered. Even later note: I ripped out the fuel header tank (see chapter 21), put aluminum pipes through the heat duct and had to lower the hole through the forward gear bulkhead again. Don't worry! I'm doing the proper fiberglass repairs as I go along.]

Note: If you're planning on installing a water cooled engine now is the time to think about pipes. Later, I decided to install automotive heating and air conditioning. Since I won't be using the heat duct for air, I can use it for pipes. I can also install my vacuum pipe down there. Getting the pipes in after the fact is a serious bear. I wish I'd installed the pipes during Chapter Eight while building the heat duct. It would have been a breeze. Details of the pipes needed and where they need to go are in Chapter 23. Also, if you're making the tubular heat duct extension, take a look at the inner tube / sand trick mentioned in in Chapter 27


At this rate I'll be done with Chap 8 before the supplies get here. Should have ordered earlier. I'm just short of a yard or so of BID. Wicks called me today. They say there's a slight stain or water mark on some of their tubing stock, so they're calling everyone who ordered it to see if this is acceptible. Wow! What service. I never came across a company like this before. I told them I was unsure, so I'd opt for the safest approach and back order the tubing till they get some better stock.

Glassing & installing the shoulder support

Just a couple of quick jobs to finish off Chapter 8. Wrong. This was one of those jobs where nothing goes right. Murphy moved in with a vengence. [Later note: This comment came back to haunt me. See Chapter 27]. I glassed the inside, waited a couple of hours, then began to install the shoulder rest. Realized I needed to flox it in. Took it off again. Floxed, then put it back. Don't ask me why, but I'd decided to thread the wires for the map light through the tacky layup. Bad idea. The plys were still too wet (75f today) and started to come off the foam. Air bubbles everywhere. Worked it all back down and left to cure for another hour or two. Did the layup of the 12ply reinforcements and cut them into squares. The squares were too big. Had to trim the wet squares. Uggh. Next came the outside shoulder rest layup. Finally got everything laying nicely. Its probably a bit heavy, but it looks fine now. If I had this job to do again I'd make the shoulder rest on the bench. Glass the inside, cure and trim. Glass the outside, cure & trim, then tape it in place. Sometimes I think the plans describe a method in order to teach us a new way to do something, not necessarily because this approach is better in this particular case. As well as being the plans to build a Cozy, this is a course in composite airplane building.

Shoulder harness attach points

This was fine until I held the alum tab while threading the bolt from above. I only just had hold of the tab. It slipped a bit and now I'm stuck. I don't have enough of a hold to pull it out of the slot, but if I let it go it'll fall down inside the shoulder rest. I'll either have to dig it out by cutting the glass, or the plane will rattle for evermore. I can't reach any tools without letting go of the tab. Painted myself into a corner. I stand there, hanging onto the tab wondering how to get myself out of this. Finally I spot the wire for the map light. I feed it down through the hole and push the tab enough that I can change my grip and retrieve it. Whew. I'll use pliers for that job when, eventually, I finally fit the seat belts.

[Later note: I wish I'd put nutplates under the shoulder support for the seat belts. The belts won't go in until the last possible stage, and I'd like to close off that hole in the front of the shoulder support.]

Seat belt final installation

About four years later, I had the upholstery in place and installed the belts. The aluminum tab thing worked fine. Once I had the bolt tight I cut off the protruding piece and flox // BIDed the hole. The belts come with a cross piece called the "sternum strap". It's installed above the adjustment hardware, but there's no way it can stay there without choking you. I lowered it to below the adjustment straps, but then it slides down to the buckle and does no good. I could stich it in place, but the belts are a perfect fit without it, and I can't imagine any way that I could slip between the belts, even in a sideways impact. As for the belts themselves - I like them. At one point I thought of having automatic belts so I could lean forward as needed. I actually bought one from Velocity to see how well it would fit. Forget it. I'll stick with the plans belts. They're an excellent fit and feel very comfortable.

Center seat belt reinforcements

OK. I've done this before. Plans don't explicitly tell you to do it on wax paper, but then they often miss out an "obvious" step as we move forward. Wet up the plys on wax paper and then lay them. Simple. Nope. Seven plys all at once just wont lay down over the seat belt tubes. No way. I had to disassemble the layup and lay the wet plys down one by one. No fun at all. The end result looks good, but next time I'd do it on the plane, not on the bench.


Having read the archives about recessing the step I did this in Chapter 7. Now I floxed the step in place and screwed it tight. Unfortunately I don't have the R18 bolts to reach all the way through the step, the reinforcement and the seat belt bracket. I'll need to get these bolts. Anyone know where from? Wicks and Spruce dont carry them any more.

Remaining minor items to do

Get R18 bolts for the pilot seat belt floor attachment. - Done. 6/00.

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