« Archives in March, 2012

Baffles: To Do.

If you don’t know what any of the terms or parts are, this won’t make a damn bit of sense to you. This is more for me to have a written plan of the order of operations to hopefully avoid some future FUBAR. So I’m going to lay out what I think is the proper op order for getting the baffles on and trimmed, the cowl finished, and the airbox done.

See, this is an interlocking puzzle, kind of like a Rubik’s Cube, but none of the pieces are square and there’s no colors to tell you when it’s right. You just need to end up with a shape that meets certain requirements, i.e. everything fits without rubbing on something else and nothing makes the prop stop spinning.

First thing to do: Clean the shop. I swear, sometimes I don’t even know why I bother having a tool box. Everything winds up strewn all over the place anyway. It’s reboot time, because when something I’m looking for is buried under crap I should have put away and it takes me 10 minutes to find it, it’s time to fix that.

So, the baffles:

1. Order new front left inlet ramp. This is because I may have already trimmed too much off the front edge to get the thing to fit inside the cowl. Have to check. I can still use the old one for lineup and getting the shape right, but there might not be enough meat on the front of it to brace the air filter.

2. Make the bracket that connects the ramp to the engine. With this in place, I’m not trying to hit a moving target as far as shaping the opening of the fiberglass snorkel/airbox, and also the angle of the front upper baffle that goes around the prop governor. OBTAIN PROPER BOLTS FOR BRACKET. Big, meaty 3/8″ Grade 8 bolts that connect to the pad just below the governor.

3. Find the rest of the airbox kit, especially the W-channels thqt hold the filter in place. I know they’re in there somewhere, I just have a filing system for parts that closely resembles the Sargasso Sea.

4. Make a collar for the opening of the fuel servo’s intake to assist in fitting/trimming the snorkel. Yeah, that should have FA to do with the baffles, but like I said, it’s an interlocking puzzle. The takeaway from this is that sorting out the snorkel before cutting any holes in the baffle means there’s no need to cut the snorkel in half and re-glass it.

5. Cut/grind off the extra ears on the starter so they don’t interfere with the snorkel.

6. Cut a relief into the snorkel so it clears the alternator bracket. This is a common mod. Why Van’s sells a part that doesn’t work out of the box with 90% of installations is a mystery to me.

7. Maybe not actual step 7, but finish the conical gusset, trimming, and fastening for the right-hand side, which seems to be working OK.

8. Glass in the top cowl inlet ramps. These will be necessary for the next step.

9. Begin the iterative process of trimming the top sides of all baffles down so the top cowl fits and the baffle seal strips will seal.

Baffles 5

2 hours.

Continuing work on the front left inlet ramp. I had to puzzle some stuff out, because this one is a little different from the right side. On the right side, bending the inlet ramp at an angle lines it up to the cowl inlet pretty well. On the left side, you need a big flat spot for the air filter. Also, the amount of crazy you get to deal with when it comes time for the filtered air box is directly proportional to how well you line up the hole in the inlet ramp for the air filter.

Tonight I cut the big stupid flange off the FAB to make the opening somewhat resemble the AFP fuel servo intake. It’s still not even close, but it’s probably wide enough, there will be more trimming. I’ll also have to do two things: Cut a relief hole in it for the alternator bracket (why this isn’t in there from the get-go is beyond me), and grind off one of the ears on the starter. When that happens, I’ve got a fighting chance of lining up the FAB where it’s supposed to go on the inlet ramp.

The other thing about the left inlet ramp is that I have to fabricate the inboard bracket that attaches it to the engine. Fortunately there’s a big square pad with two 3/8″ threaded holes exactly where I need them to be to mount a support bracket for the inlet ramp. After some diggin on VAF and around the internets, I’ve found that even with the bend in the inlet ramp, the filter will still fit, because it’ll flex around the bend. Then the FAB just has to be trimmed to accommodate the shape, and it’s on.

Baffles 4

5 hours.

Yesterday and today. I’ve been dreading this, mostly because the baffles are, uh, baffling. But with the cowl halves fit, it was time to seriously tuck into these things. Friday, I got a present from American Propeller, my new PCU5000x. I think they put the wrong spring on it, because the spring returns the control lever to the low-rpm position, but that’s no biggie, they can send me a new one. Either that or I pooched the order, which would suck, but it’s not a showstopper, I’ll just have to run the cable up from the bottom.

It’s a lot less bulky than the old McCauley that was on there originally, although I might have to reclock the bracket to clear the cowl. This is done by drilling a couple of offset holes in the bracket.

Yesterday, I farted around with the baffles for a while, putting them on in preparation for cutting the front ones to the cowl. I figured I’d be fancy with it this time and make some cardboard templates to get the shape right. This didn’t work out all that well. My plan to set it up like Bill Wightman’s installation didn’t work at all, because I couldn’t for the life of me transfer the shape of the governor pad onto the cardboard with any degree of satisfaction.

It seems simple enough, but it’s not, and I couldn’t quite make it work.

What I wound up doing was using the IO-540 baffles from the RV10 kit I’d ordered a while back. For some reason, this option dropped almost right into place. I had to modify the right side baffle to match the angle of the inlet ramp, but that worked out pretty well, once I actually figured out a good way to measure and cut it. The left front worked out fine, since the pre-cut hole was actually designed for a governor the size of the PCU5000X.

Today’s efforts consisted mostly of putting the bottom cowl on and taking it off again. A lot. I trimmed the front side baffles to clear the cowl, then worked on getting the proper shape for the right side.

This is the left front trimmed back enough to clear the cowl and nest in the spot just outboard of the cowl inlet.

Cutting the shapes was actually easier than I thought it would be. There’s a lot of extra metal on the front inlet ramps, maybe these things are designed to work with a variety of configurations, but the basic deal is that you have to trim everything so it tapers down to the rough opening of the cowl inlet. It takes several iterations.

Once you have the basic trimming done, the front inlet ramp comes off and you have to bend it along a line that starts at the point where the cowl inlet edge is tangent to the ramp surface and ends up in the corner where the front side baffle and inlet ramp connect. The bend brings the front ramp roughly into line with the inlet.

Like so. There’s still more trimming to be done, because the way this works is that a strip of baffle seal material goes around the pink bit and seals against the ramp and sides. On the right hand side of frame is the 540 front baffle. I’m not promising this is going to work, but it seems to fit OK., and if it doesn’t, I can use it as a template to cut on one of the spare 360 baffles I ordered from Van’s just in case.

Also a conical gusset goes in the corner where my fingers are, one that more or less matches the shape of the inlet. This does two things, it gives a better seal under pressure and stiffens the structure where the air comes in.

After that’s all done comes the fun part: Trimming the upper edges all around to match the contours of the top cowl.

Oil Door.

6 hours.

Yesterday and today.
Yesterday I worked on the oil door. The finish kit comes with a fiberglass version, and it’s meant to be held down with an elephant-ear Camloc fastener, but it looks like ass if you do it that way. A better alternative is the Nonstop Aviation hidden hinge kit.

It mounts the door on a sprung hinge that opens up and out of the way of the cowl. You can use the fiberglass part from the kit for the actual door, but like some others have done, I made mine out of .032 aluminum. The reason? When the fiberglass part gets heated by the engine, the pressure from the hinge trying to open will warp it. Aluminum has no such limitation.

Once the door is cut, formed and drilled, the flush-mount Camloc release latch goes on. I actually made two of these things, because I screwed up the Camloc location on the first one. No biggie. I still have half of a .032 horizontal stabilizer I’m using for stock.

When it’s all in place, it closes flush and latches properly, but getting the hole for the latch handle was kind of a bear.

When it’s open, the spring keeps it out of your way so you can check oil, remove hinge pins, etc.

Today I was doing more checks of things under the area where the top skin will go, because that’s going to have to go on soon. I spent some more time securing wires and torquing down Adel clamps. In doing so, I found that I never riveted the row on the longeron right next to where the canopy closes. They leave them open at the QB factory because the slider canopy mounts a little differently. This isn’t all that easy to deal with when the panel and other things are installed, but it’s not that bad either. All I had to do was disconnect the vent hoses so I could get hands and bucking bars up inside the channel by the longeron.

After that, I started putting the baffles back on, but didn’t get very far. I’ll do some more of that tomorrow.

Cowl Fitting 6, 7

13 hours.

This counts last weekend as well, and I suck for not making the update then, but I had some pressing stuff going on. Anyway, more stuff happened on the cowl, mostly fitting, shaping, and the drilling of hinges.

Before I get into all that, I’m going to post some photos from the last entry.

To rough in the landing gear cutouts, I had to use a piece of angle, where I marked the distance from the center of the airplane to the landing gear leg.

The idea was to transfer that measurement to the bottom cowl to mark the approximate place the landing gear cutouts needed to be.

Like so. Although, the fiberglass flexes so much any measurement would have been approximate at best, so I left plenty of room for error. Fiberglass isn’t like metal, if you cut too much away, you can build it back up, but it’s a pain in the ass.

Remember I said I did a lot of hinges? Here’s one almost done on the bottom cowl. This is a piece of piss. Cleco-clamp the hinge to the edge, drill 1″ holes along its length. Easy.

The side hinges weren’t too bad either.

But the fun comes with you have to drill holes in the fiberglass on hinges it covers up. This is where the new pink cowl with its honeycomb structure help a lot. What I did (and I learned this from Bob Collins, thank you Bob!) What I did was put the cowl on, and fine tune the fit with some of that PVC tape I had lying around. It’s great stuff, super strong, and doesn’t have all those fibers like duct tape. Then I stuck a light up inside the cowl, pointing at the hinges, which I’d already drilled holes in.

With the light inside, the holes in the hinges light up the fiberglass and gave me a really good drill guide to complete the task. The first one sucks. You have to somehow hang on to it and make sure the drill goes in right, otherwise it can oval out the drill hole.

The desired result is Clecoes holding the hinges all the way up and down the line.

More or less like this.

The other fun bit is figuring out what to do with the hinge pin. I have to drill a slot for it to enter and exit the hinge, and I’ll have to conceal it later.

Like an idiot, I didn’t cut out the oil door per the plans before starting the hinge fit. It didn’t seem to have any ill effect, but after the hinges were drilled, I took the cowl apart and cut out the hole for the oil door.

But I didn’t get much past this part. It was Oscar night, and we in the movie biz make a big deal out of it. It’s also cool to have 5 friends nominated this year.

This week was killer, so I got nothing done. But today was pretty solid.

I didn’t get a super-early start today, because I took simba down to Marina Del Rey for his walk.

Today, I riveted the hinges to the cowl.

The blue light from outside on the pink cowl makes everything look like it was shot in a Miami disco in 1983.

Riveting these was tedious and repetitive. Like these photos.

But eventually all the rivets got done, so I started working on the inner flanges, which get platenuts riveted to them and the two halves screw together through them.

The smaller hole was the temporary one I used to hold the two haves together during fitting. it will get filled in when I go into fiberglass mode.

And that’s it. tomorrow, I’ll probably work on cleaning up wiring so I can rivet on the forward deck skin.