« Posts tagged fiberglass

Baffles 12

7 hours.

If I had a time machine, I wouldn’t go back and tell 1984-me about all the cool stuff in the future, or bet on all the baseball games, or ram a pickup truck into a sleeping Mohammed Atta. OK, maybe I’d do that. But what I’d definitely do is tell 2005-me that under no circumstances should you purchase an engine off eBay, and if you do, make sure the damn prop governor is in the back.

I’ve spent more time than I care to think about figuring out just how the hell the cowl intakes are supposed to interface with the baffles via the rubber airseal material. There are no guidelines for this, here there be monsters, etc. The io-390.com site has a lot of good information, but as with all things cowl and baffle, everybody’s setup is just a little bit different, and I’m basically having to roll my own solution anyway. This is not necessarily a bad thing. I just wish I knew a lot more of what I know now back before I started.

The major issue comes from figuring out the shape of the airseal on the front baffle on the left side, the one that wraps around the prop governor. I think I have something that works, but I’m not 100% happy with it, and I wish I knew how to do it better. But it looks like what I’ve done will seal the high-pressure area under the cowl, and when I get back from Toronto, I should be able to finish cutting the airseal strips for the rest of the baffles. I should also be able to bond the inlet ramps to the top cowl and start filling in the tunnels on either side of them. The idea is to keep air from spilling out of the high pressure area into the area below the engine. The pressure differential is what cools the engine.

If I didn’t have this stupid front-mounted governor, the standard baffle kit would fit fine and I would probably be on to plumbing and wiring by now.

Baffles infinity.

7 hours.

Memorial day weekend was decent. Got a bunch of stuff done, mostly trimming down the baffles. The final trimming still isn’t done, but I got the contour of the top inlet duct cut in. Very iterative, time-consuming process. I have to say, I’m still not altogether clear on how the airseal is supposed to work around the cowl inlets. There’s some airseal that’s supposed to go on the bottom inlet half, and I guess that’s supposed to overlap with the stuff on the baffle somehow.

the other problem I have is just how little metal I’ve got on the front baffle at the top of the arc near the governor drive gear. Still, that has to be fastened to the engine somehow, and I suppose I can reinforce it when I devise some clever system for attaching it to the engine.

I also drilled the fiberglass inlet ducts into place. Now that I have them locked in, I can glass them and fill in the inboard side so air doesn’t blow through and cost me pressure.

Apparently this game is all about air pressure, specifically, making sure that air flows through the engine compartment the way it’s supposed to, which is over and between the cylinders. I read somewhere that gaps totaling up 1 square inch where they’re not supposed to be will cost 20% of the cooling capacity. This would not be good. At all.

First thing that has to happen though is the baffles have to come off, get final trimmed, and deburred. Maybe painted. Not sure about that.

I’m starting to see one of two things: Either it’s the light at the end of the baffle tunnel, or it’s a train, which means I’ll wind up redoing them.

Snorkel and Baffles again.

8 hours.

Yesterday and today. I’ve been blowing this off, mainly because there was no good time to spew fiberglass dust all over myself, and the fact that I accidentally sheared off the cord of my Dremel tool with the fiberglass bit last time. The sparks were epic. Yes, that was stupid. So yesterday I went to Home Despot and picked up a new Dremel 4000, and this time, I got the flex-cable attachment that lets me use the thing a lot more like a pencil or some other fine instrument.

I tried to take a lot of pics, because the process of fitting the VA-132-1 snorkel to the AFP FM-200 fuel controller and the front inlet ramp is a complete and total whore. Hopefully my documentation can help somebody have less of a ride thorugh hell. There is very little in the way of direction in the plans that actually provides useful information. About the only thing I needed the plans for was to tell me which side of the snorkel the filter mount flanges go on. It’s the inside, in case you’re curious. Oh, and the reference photos on the plans are terrible, and there aren’t enough of them to give you any in-depth information as to how things are supposed to fit. Yes, I get that there should be a big square hole in the front inlet ramp that should have an air filter under it. All aboard the NS Sherlock. Even so, fitting it to the AFP fuel controller brings with it its own set of travails, which is largely the root of the issue. Now, the FM-150, released the year after I got mine, has a square flange on it, like the Bendix or Precision Silverhawk servo, which means the snorkel will fit a lot better. Too late for yours truly, however.

So today, I was determined to make the filter mounts and mash up the parts necessary to make the filter fit.


This was the state of affairs after trimming the snorkel to match the contour of the inlet ramp, bend and all. This was a tweaky, iterative process, the first of many. With the snorkel attached to the fuel servo (throttle body), I had to trim away millimeters of material until it was kinda sorta flush with the contour of the inlet ramp, including the bend in the material designed to match the contour of the cowl opening.

With this in place, I was able to trace the shape of the snorkel opening onto the bottom of the inlet ramp.


View from the top, before anything was cut. At this point, I’m test-fitting the filter retainer, which is going to connect to the whole apparatus by way of #6 screws.


I gave myself plenty of room to work. The initial cutout for the opening was about 3/8″ inward from the actual edge. I wanted to make sure things could shift around a bit when installing the W-sections that would become the filter mounts.


First step was the aft side, which is the hardest, because there’s a joggle downward from the angle attached to the cylinders and block to the actual ramp. This means that the W-section of metal designed to accommodate the filter needs to fit in there, and match the angle of the snorkel’s surface. This was not easy, and I think I’ve got enough edge distance to get by, but I’m not altogether sure.


So after cutting away a good amount of the flange on the filter mount, and bending the metal to match the angles, I got a pretty decent fit. Here, you can see the metal flange through the fiberglass, with positions marked for where the rivet holes are going to go. It was at this point I figured I should take a look at the drawings, useless as they are, to make sure I wasn’t committing an obvious error.


Once this one was nailed down, everything stopped moving, and it was much easier to work with the whole assembly with it anchored at both the servo end and the filter end. Good thing I checked the plans. As mentioned before, the flange goes on the INSIDE of the snorkel chamber, not like it is in the previous photo. Fortunately, there was enough give to let me squidge the snorkel back enough to make this work. But blocking it out like this gave me a perfect reference as to where to cut down the snorkel to clear the joggle on the W-section.


The next filter mount section was relatively easy. Too bad I cut the W-section too short with the bandsaw. Stupid muscle memory. I thought about it, I double checked it, I marked it, but I wound up cutting it too short anyway. Not a big deal, I have a template now, and I know how it’s supposed to go. Replacing it will be simple. The next step beyond the filter mounts will be opening up that inital cut to clear the horizontal part of the filter mounts. The idea is that the air filter rests on the joggle in the W-sections, but the forward lip of the filter just slides in under the opening.


To get the outboard one, I had to shave down the filter mount flange at a slight angle. I also finally had to bend the lower flange on the outboard baffle to match up with the inlet ramp. But this actually made things easier. Plenty of edge distance, and the third filter mount went on no problem.


A closer look at the outboard filter mount, from the front. The little piece of metal that looks like a ‘J’ is the horizontal part of the W-section where the filter lip rests. The snorkel will still have to be trimmed up front to allow the lip to clear. Probably should have photographed the filter a little. I will next time.

So that was the scary bit. I had no desire to start anew with a new snorkel (which is pricey), and other than the inboard filter mount, I don’t have to order new parts. It’s an iterative tweakfest, but eventually, things stop being awkward and you can actually get some stuff done. Just to make sure I wasn’t crazy, I put the lower cowl on, and everything seems to clear just fine, but the cowl will require a little bit of trimming.

Next is to enlarge the filter opening and make the filter retainers, and install the K-1000-6 platenuts that hold the whole thing together. Once that’s done, I can finish the front baffles, which are going to be interesting on their own.

More snorkel!

3 hours.

Short day today. This morning was an Easter Egg hunt and brunch, so I didn’t get going until about 1 or 2. My setup for glassing the opening ring of the snorkel worked great, but the resin adhered to the demoisturizer container/plug a little too well. It cracked the container when I wrenched it out of there, but it didn’t make a huge mess. I spent some time sanding down the inside of the snorkel to smooth out the bumps, and it seems like it’ll work OK.

I did get the snorkel on in preparation for trimming the filter end to fit the contour of the inlet ramp, with its bent-up section as called out in the plans. I’ll post some photos later, but the main issue is one of reference. To get the snorkel on in its pre-trimmed state, the inlet ramp needs to come off. But then there’s no reference to where the inlet ramp is actually going to be. fortunately, I marked on the side baffles and the engine where the inlet ramp fits, and through the use of cleco clamps, angles, and a steel ruler, was able to transfer those references to the snorkel. It’s going to be hard, and it will take some iteration, so the key will be not trimming away too much of the snorkel during the fitting process. However, if that does happen, it won’t be a total disaster, I can always cut away enough to make absolutely sure it clears, then extend it to the baffle using new fiberglass, and doing that will insure that it absolutely conforms to the inlet ramp shape.

Snorkel Again, and Exhaust.

5 hours.

Today I did some more work on the snorkel, this time trying to shape the throttle body side to allow for smoother airflow, fill in some voids in the opening, and generally beef the thing up where the interface is.


This is looking into the relief hole I made for the alternator. You can see that the demoisturizer container serves as a perfect plug in place of the throttle body and the tape wrapped around it is exactly where the lip on the TB would be. The dark bit on the right inside the hole there is a void that didn’t get filled on the last glassing pass. I roughed up everything, cleaned it out, and went to town.


This is looking in from the top, where the air filter will go. It looks pretty anatomical, I know. The thing I have to fix now is where the opening bulges up, which will create a turbulent airflow.


Weapons of the trade. That’s the Builder Shield plastic on the left, and West System 206/105 epoxy resin on the right with the pumps sticking out. Living 3 miles from Marina Del Rey, I’m fortunate to have a West Marine store where I can buy this stuff. I wanted to get the 206 hardener, because I needed more pot life from the epoxy. I can wait the 10-15 hours for it to cure.

The photos stop for a bit, because of the whole resin/iPhone thing again. The next step was mixing up a bunch of micro to fill in some voids and take a crack at shaping a more gradual transition inside the snorkel where that burble was going to be. The first thing to figure out was how to fill in the voids around the actual opening itself. What I wound up doing was fairly genius (assuming it comes apart properly tomorrow). I wet down a strip of glass cloth, put it on the inside of the opening ring, then jammed the plug through it. It should form a perfect shape around the plug, and I can easily cut/sand off the excess on either side.


Here, it’s about done. There’s micro in there, and a couple of layups of glass around the burble and the rest of the edges go hold everything down. I also put a couple more layups on the outside to thicken up the interface ring.

With that curing, I went hunter-killer on some of the smaller items that I’ve been blowing off. First thing was reclocking the prop governor cable bracket.


This bracket also goes on the IO-540 in the RV-10, but the -7’s cowl doesn’t have enough clearance to let that happen. I’ve seen one or two examples of putting a bump in the cowl to allow the bracket to clear, but since I want to do as little fiberglass as possible, I decided to reclock the bracket. That just involves drilling two offset holes. The bracket will stay on just fine with two screws. I didn’t need to do much, that’s maybe a quarter-inch of distance between those hole, but I managed to bring the end of the arm down enough to where there won’t be any interference issues with either the cowl or the #2 injector line.

Since it’s time to think about things like control cable and wire routing, I decided I should probably put the exhaust system back on. The more things that are actually on the airplane, the fewer guesses I’ll have to take when deciding where to run things. Forward of the firewall, the name of the game is keeping things from picking up too much heat, and the primary source of that is the exhaust. The recommended distance between the exhaust and anything else is half an inch. Anything comes closer than that, and it needs to be shielded.


What you see here is the 4-pipe Vetterman exhaust I had to purchase to replace the crossover 4-into-2 type I had before. With the Crossover exhaust, there’s absolutely no way to get control cables to the throttle body without a horribly complex series of bellcranks and other things I really don’t want to mess with. The 4-pipe setup has a nice wide space up the middle where I can route the mixture and throttle cables without getting them too close to the pipes.


Since the right aft baffle is already on the engine, and finished enough to matter, I thought it might be a good idea to get the two-pipe cabin heat muff set up, along with the suspension by which the aft sections of the pipes hang. I’ll admit, I can’t find the instructions or drawings right now, but it really only makes sense to put it together one way. This is all about making sure I have all the parts, which I do, except one of the nuts is defective. There are no threads in it. I don’t even know what that type of fastener is called, to be honest, so I’m going to tap it for whatever threads the connecting rods between the brackets are. Like the crossover version, the pipes hang from stainless steel tubes connected by sections of rubber oil hose, so that’s no mystery. But with this and the baffle in place, I’ll be able to hook up the cabin heat system.

Snorkel 1.

7 hours.

Saturday and Sunday. The snorkel fit fine with no modifications. April Fool’s! Seriously, this thing is the biggest POS in the whole inventory. There’s no way it will fit without mods, ever. It doesn’t even fit well with the engine Van’s sells. It is a black hole of suck, no two ways about it. Firstly, I hate fiberglass. Second, I have the AFP fuel injection system. Third, this thing has to line up in at least three places before it can be said to ‘fit.’ Let’s have a look.


What you see here is an attempt to make a plug in the shape of the throttle body intake. To do this, I make a ring out of .032 aluminum, then riveted it to another ring just inside that one, with the shop heads sticking out. This slipped over the throttle body intake and the idea was that I’d tape it off, fill it with spray foam, and have a perfect foam plug from which to form all my fiberglass and use as a sanding block later. No such luck. The foam can I used had probably been sitting on the shelf for about 6 years or so, and never quite cured. Mess. And before you ask, yes, I taped up the throttle body so no goo would get down inside. Back to square 1.

I don’t have a lot of pics of the snorkel in its totally hacked up form, because I didn’t want to get fiberglass dust all over my phone. Basically, I had cut away pretty much everything near the flange of the snorkel, leaving a hole big enough to get the throttle body into. A lot of people cut the snorkel in half and re-glass it back together after fitting each half, but I didn’t want to do that, for some reason. Since I was committed to glassing a whole new flange on it, I didn’t see the need to cut it in half. So that led to the next process:


When fitting this thing, not only does it have to line up on the throttle body intake, the filter end has to line up on the left front inlet ramp, and it has to do it while clearing the #2 oil line, the governor baffle, and the front side baffle. Plus there needs to be enough meat around the edge of the air filter hole to attach the supports and meet any riveting edge distance requirements involved. The only way to get it into position is to take off the inlet ramp and try to fit it that way. surprisingly enough, this does work. I wound up suspending the snorkel in a cat’s cradle of PVC pipe tape (all hail pvc pipe tape, that sh*t rocks!) in the position it would eventually be in once everything is glassed and cut.

I also found my new best friend for fiberglass work: Contractor’s carpet guard. This stuff comes on a roll like Saran Wrap, and it’s the stuff contractors lay down on your carpet before they start trudging in with muddy boots and taking out old sewer pipes. It has a mildly adhesive backing, and it clings to itself and smooth surfaces like crazy. Think of the blue stuff that comes with Van’s kit parts, but clear. It leaves no residue behind either, although they do recommend you don’t leave it on for more than 30 days. Anyway, this stuff became the new throttle body condom, as well as a wrapper for anything else I didn’t want to get stray resin on. I took the alternator off, because it was seriously in the way, but I just wrapped a bit of this stuff around the starter and the alternator bracket. Oh and all over the throttle body. Like so:


Here’s a mostly side-on shot of the opening in the snorkel next to the throttle body. As you can see, it’s not even close. But with the TB protected, I can slap glass on this thing until the cows come home.


From the back.

Now the photos stop, because I’m not about to get resin all over my phone. I used two layups of the same stuff I had when I did the canopy. I’ve got a crap-ton of it left, wo a few pieces got me through. I was able to make a decent connection between the TB and the snorkel, the end result of which is this:


A perfectly-shaped snorkel-to-throttle-body interface. OK, not perfectly shaped, but close enough to keep going. This is after 8 hours of cure. There are some voids where the plastic wrinkled around the throttle body opening, but that’ll get fixed in the next couple of days or so. I did find a perfect facsimile for the throttle body opening though. At the hardware store, they sell this demoisturizing stuff. It’s basically little balls of salt, but what’s of interest to me is the container. The container is smooth plastic, and it’s exactly 3.25″ in diameter, same as the throttle body. Half an inch up from the bottom, I wrapped about 1/8″ thickness worth of pipe tape around it to simulate the lip of the TB, and I was able to use that as a plug for the next 3 layups of reinforcement of the opening.

The inside is a different story. I’m going to be in there with micro, shaping a smooth guide for the airflow around the parts that indent too far into the snorkel chamber and will cause turbulence rounding the corner into the throttle body. That’s when I squidge some micro between the plug and the interface there to fill the voids as well.

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.

Wiring and fiberglass.

12 hours.

This is for yesterday and today. I finished up the elevator and HS fiberglass tips. You’ve heard me piss and moan about fiberglass before, so I’ll spare you that this time, but yesterday’s experience was not great. I got the HS off the futon in the other room and set it up on the bench so I could mount and balance the elevators. When I last left the HS, I’d done the fiberglass tips, but I hadn’t done much else with them, and they needed a good amount of shaping before the elevators could swing freely. One side was fine after some filing and sandpaper, the other had the foam too close to the edge so I sanded all the way through the filler and started taking out foam.. This isn’t good. Raw foam isn’t helpful, so I had to mix up some flox, both to fill in the elevator tips after balancing and reinforce the left HS tip. I had this cool thing set up where a thin piece of sheet was curved round the elevator tip, making a form for the flox that would guarantee the free motion of the elevator through its travel.


Would have worked too if the tape hadn’t popped loose, leaving me with a distorted lump of flox on the front of one elevator. I had to file/sand that back into shape, then glop in a load of micro filler to get the final shape.

So there it is curing away.

I busied myself with antenna mounts while the epoxy was setting up. First was the transponder antenna. I’ve decided to put this on the floor behind the baggage bulkhead. All antennae need doublers, even the stubby transponder antenna. The skin of the aircraft isn’t thick enough to provide structure on its own, so I had to take a piece of .063 and make a plate that the antenna can grip onto.



Today I did the final shaping and priming of the HS and elevator tips. While I was waiting for paint to dry, I worked on the doubler for the Garmin GPS antenna.

Installing these doublers aft of the baggage bulkhead is interesting. First thing you do is drill the holes in the plate at four corners, then one in che center. Then you go inside the ship, down the Jeffries Tube, and position the plate where you want it for proper antenna location. Don’t forget to bring your drill. Use the plate as a guide, and drill the skin using the center hole in the plate as a guide. Then measure to square the plate up with surrounding stuff, then drill the corners of the plate. Now it gets fun. You have to dimple all four holes in the skin that match the corners of the plate. You need to use your 3/32″ pop-rivet dimpler for this, but you do it by crawling into the ship, placing the dimpler, getting back out, making the dimple, then repeating 3 more times. In the case of the GPS antenna, there are also screw holes to deal with, which means platenuts. Oh, don’t forget to countersink the skin side of the plate.

Since I was in the tailcone a lot today, I figured I’d do some nagging things I was going to have to do anyway, like the restraint cable clevises and removing the ELT antenna cable. Yeah, can’t run the ELT cable through bulkheads. If you crash, the airframe might fold and sever the ELT antenna cable where it passes through a piece of sharp metal. I decided to run the trim servo wire down that run in its place. Then I ran the transponder antenna wire alongside the two GPS wires on the left side and did the BNC connector.

I don’t want to spend a lot more time down there. It’s cramped, hot, and dusty in there. If I can get enough servo wire slack so I can work on the connector outside the ship, that will make me extremely happy.

More emp tips and the strobe head.

4 hours.

You know by now that fiberglass is not my favorite medium in which to create airborne works of art. Mostly it’s the mess, but the big minus is the cure time. I filled the ends of the empennage tips with foam, laid up some fiberglass on each side to stiffen it, then slathered on a nice frosting of micro. I had to take another run at the micro to fill the low spots, but this time I mixed it a little wet. Of course, this necessitates putting the pieces in a position that will allow the filler to flow out flat along the backside, like so:


This tree, cobbled together with clamps, tongue depressors, and scrap angle, allowed the filler to behave as if it was cast in a mold. There’s still a modicum of shaping after this, but these are nearly done.

But I had to do something else while this was curing, so I tackled the thing I know I have the resources for. A while back, I verified that the strobe unit worked. Now it was time to stick it in the plane. I’m going to worry about wire runs later, but I mounted it just behind the baggage comparment bulkhead on the passenger’s side. This is a fairly common location, and will do the job nicely. But I’m out of practice with metal. I went through three plates before I got one that fit right. There are two pieces of angle a little wider than the strobe head, fixed to the J-stringers between the longeron and the floor. Drilling them to the J-stringers was not fun, and neither was riveting them. But they did eventually go in. Here’s a shot of one of the angles clecoed in:

And this with everything assembled and riveted: