RV-3B Dave's in Colorado

[scsmith]

Dave,
This is also a good time to fabricate a radius "bump" along the bottom edge of the firewall where it intersects the belly. I see there is an engine mount tube that traverses there, which complicates things. I would try to make a fairing that fits over that.

Take a look at a couple of recent threads on this subject for some pictures and ideas. In your case, I think a 1.5" radius semicircle that fairs tangent to the belly skin would be great. This will make a huge difference in cooling flow exit velocity and uniformity. It is really worth the trouble.

 

[David Paule]

Steve, I got sort of discouraged with that. I'd planned from the beginning to include that and in this post above you can read why it's not there. I chopped it off.

In retrospect, a better-designed belly overlay with a longer transition aft of the radius would have been better, but by that point, this one was glued and riveted on and I wasn't about to change it.

Fortunately, RV-3s and -4s generally seem to cool relatively well. your suggestion remains as a possible follow-up at some point. Interestingly, just last night I sketched up a way to make such a radius built into the lower cowl. It would fit but be a bit awkward.

The lower contoured line is the aft edge of the lower cowl, forward to the upper left. The depressions at the outboard ends are for the exhaust pipes. The stuff in the center is the duct, raised on walls that form a tunnel. Hard to radius the forward edges of those because that would interfere with the exhaust. The radius is the front part. The aft edge would need to stick past the aft edge of the lower cowl and press against the titanium belly overlay, but any fasteners would protrude into the cabin floor, an ungood thing.

I seriously doubt that I'll build this as sketched, but it's one way of doing it.

Dave

 

[scsmith]

Very interesting idea, assuming there are no braces or struts or exhaust hanger brackets in the way.

Steve, I got sort of discouraged with that. I'd planned from the beginning to include that and in this post above you can read why it's not there. I chopped it off.

In retrospect, a better-designed belly overlay with a longer transition aft of the radius would have been better, but by that point, this one was glued and riveted on and I wasn't about to change it.

Fortunately, RV-3s and -4s generally seem to cool relatively well. your suggestion remains as a possible follow-up at some point. Interestingly, just last night I sketched up a way to make such a radius built into the lower cowl. It would fit but be a bit awkward.

The lower contoured line is the aft edge of the lower cowl, forward to the upper left. The depressions at the outboard ends are for the exhaust pipes. The stuff in the center is the duct, raised on walls that form a tunnel. Hard to radius the forward edges of those because that would interfere with the exhaust. The radius is the front part. The aft edge would need to stick past the aft edge of the lower cowl and press against the titanium belly overlay, but any fasteners would protrude into the cabin floor, an ungood thing.

I seriously doubt that I'll build this as sketched, but it's one way of doing it.

Dave

 

[DHerzTX87]

Man, that sure isn't much exit area for cooling air flow across the engine.

 

[David Paule]

I fitted the turned-down tips to the exhaust. The hose clamps aren't on yet.

Here’s a side view.

The oil door wire pull bracket was too high and would contact the engine. I eliminated it and just clecoed on a bit of piano hinge.

And it’ll fit! Plus, bonus, it works!

Next, the cabin heater muff and carb heater muff got a trial fit.

The cabin heat muff only fits on the right side (left in the photo) but the cabin heat valve aims off to the left (to the right in the photo, out of sight on the firewall). All the cabin heat hardware is 1.5” except the inlet, on the right aft baffle, which is 2”. This isn’t currently on the engine. I can change that diameter. There would be a very long SCAT hose to the valve, though, due to its orientation.

The carb heat muff fits best on the left side but touches the lower cowling. I think I can relocate it and avoid that interference. The muff’s inlet is that opening on the non-hose side and takes lower cowl air. The hose will have a fairly direct path to the FAB, eventually. This hardware is for 2” SCAT hose. This shows the misfit at the cowl, where it's touching.

And here’s a shot of the relocated muff, with the outlet opening aimed at where the FAB connection will eventually be, an altogether better location.

Haven’t attached the exhaust pipe hangers but I’ve looked at them. I’m still working on the cowl, after all.

On the cowl, I added one layer of glass to the top cowl’s aft edge on both the inside and outside. Partly it was to toughen it and partly to cover some carbon.

Right now it's 1 degree F outside and 65 in the shop.

Dave

 

[WillG]

Cabin Heat Muff

Dave-
What is your Cabin Heat Muff Source.
Thanks
MG

 

[WillG]

Heat Muff

Meant to say -
From Vetterman, A/C Spruce -?
MG

 

[David Paule]

Got it from Robbin's Wings, here in Colorado, a few years ago. I don't know if they are still in business but they no longer seem to have a web site.

Richard Robbins
Robbins Wings Inc
7087 W. 94th Ave
Broomfield, CO 80021-4818
303-423-7002 (?)

The aft-most tube of that muff isn't exactly aligned conveniently.

At the time, I had a concern that some of the smaller vendors would retire and close. Apparently he did. Where I knew what I wanted, I went ahead and bought the products. Good timing, as some of these things aren't available now.

Dave

 

[Dan 57]

Still avidly following your build Dave, and happy to see you’re able to make good progress since my visit

All looking good, just be sure to leave enough room for them pipes to move around whilst starting/shutting down that engine… always been amazed at how much an engine wobbles during these phases.

Best.

 

[WillG]

Heat Muff

I though that it might be from R.W.
hadn't seen any advertising from them in while.
Good thinking ahead.
I have the same exhaust set-up, I did cut about 3" of the pipes
before installing the turn downs - we'll see.
I'll have to try to fab some duel pipe end caps for that Muff.
Thanks
mg

 

[David Paule]

The seat cushions arrived, un-upholstered, from Oregon Aero for a test fitting. They need a fair bit of rework, so it was good to have them to assess what’s next. They are now back at Oregon Aero. If you’re considering custom seats, consider adding two or three iterations of shipping to the estimate.

Continued tweaking the cowl, and like many of you, it’s a frustrating experience for me.

Then I had a bit of inspiration - since I was taking the cowl on and off so much anyway, why not use those cycles to trim the baffles? Turns out that although the baffles are a welcome change from the fiberglass, they are mutually incompatible. - if the baffles don’t fit the cowl won’t, and then there’s no cowl work to be done. I started by omitting the forward half of the baffles because they won’t go on without trimming. The back ones will since they only contact the upper cowl.

After some trimming (and over-trimming the RH aft piece, replacement part on order) I was ready to try the paperclip trick. Here are some paperclips after a couple of cycles of measuring and adjusting. I learned some things about this.

1. I didn’t know if a standard paperclip would work so I got large. This proved a reasonable idea.

2. As you can see, I am doing this with the blue vinyl on. This gives a somewhat slipper surface for the paperclips to grab, and I had to slightly bend each paperclip to increase the grabbing force. Paperclips might work better on bare aluminum.

3. The paperclips tend to bend over sideways. Measure from the apparent surface of the cowl to the baffle. Instead of measuring in a vertical direction, the measurement is perpendicular to the baffle contour line.

Since I was afraid of over-trimming other pieces, I took it slowly. Slowly, in this context means lots more reps of measuring, trimming, reinstalling paperclips, fitting the top cowl, repeat.

For me, trimming was either with snips or the bandsaw. For most cuts, the bandsaw was much easier. For short fairly straight cuts, and there weren’t many of those, snips worked perfectly fine. If your snips cut .032 aluminum like paper, hey, go for it. For mine, .032 is close to the limit.

So far, I haven't the slightest idea where I'm going to mount my non-standard oil cooler, except that I'm hoping to put it forward of the firewall.

Dave

 

[David Paule]

I somewhat over-trimmed the aft right baffle and had to order a new one. It came with none of the blue vinyl, just bare aluminum. I trimmed that one and finished trimming the sides. Still haven’t started the front pieces. Heres the bare naked replacement baffle in place.

In the middle of the trimming. Still using the paperclips.

Since this is an RV-3B and has the cowling cheeks, the side baffles get narrower than for the side by side models. The side baffles have a joggle at the top where the aft side nestles into the front side. In my case, I trimmed them off, and then used some magnets to hold the front and back sides together. The orange magnets are merely tooling here.

My Vetterman exhaust system uses a horizontal cross bar to stabilize the four pipes. I have it in place here, temporarily. The fixtures to something above that keep the assembly from falling down are not yet installed.

These are here to align the exhaust so that I can build the glass fairings on the bottom of the cowl for them.

While I was doing all that, I was thinking about how I’d actually make the fiberglass fairing where the exhaust protrudes through the back end of the cowl, one of the many things I needed to figure out for this airplane. I looked through my handy collection of photos and saw numerous shape variations, and my mentor recommended the absence of a fairing - which has it’s attractions. Ultimately I cut some pink foam into strips as a starting point. Here are the foam strips.

Dave

 

[scsmith]

So far, I haven't the slightest idea where I'm going to mount my non-standard oil cooler, except that I'm hoping to put it forward of the firewall.

Dave

Now that right there is funny enough that I just sprayed wine all over my monitor!

My recommendation is to mount the cooler perpendicular to the firewall somewhere, and make a fiberglass transition piece that turns the flow 90° and transitions from 3" SCAT in your case to the cooler.

Other than for access to other stuff, you don't need hardly any additional room from the back of the engine to the cooler, it could squeeze in just about anywhere.

 

[scsmith]

While I was doing all that, I was thinking about how I’d actually make the fiberglass fairing where the exhaust protrudes through the back end of the cowl, one of the many things I needed to figure out for this airplane. I looked through my handy collection of photos and saw numerous shape variations, and my mentor recommended the absence of a fairing - which has it’s attractions. Ultimately I cut some pink foam into strips as a starting point. Here are the foam strips.

Dave

Start out by cutting clearance slots about 3/4" or 1" in your lower cowl around your pipes, so they can exit where you want them. Then, wrap your pipes with 1/2"--5/8" of stuff, (foam, cardboard, whatever will wrap around it and give you a surface. Then, cover that wrapping with packing tape and lay up a couple of plies of glass cloth on that. This will give you the foundation to build more plies of glass and including nice radii in the intersection between the normal cowl contour and the pipe wrap areas.

We use a higher temperature epoxy for the cowl areas like that which live close to the pipes. We use PTM&W 2080. I can probably send you a pint or so. It needs a post-cure up to 150F to get the higher T_g and good toughness, so you need some way to get it warm after you do the layups and initial cure.

 

[David Paule]

Steve, thanks for the comments. I'll certainly remember what you suggested for the oil cooler.

The cowl was already cut out to allow for the pipes - had to do that to get the lower cowl on with them in place. I've started gluing the foam strips on; once I've shaped them and laid up some glass, they'll get removed and the glass glued on. I'll have some photos in my next post. The only 5 minute epoxy I had handy was from the local hardware store, it worked and that's about all I'll say for it; I won't buy that product again. Except for the hassle of removing it later, it's adequate.

Thanks for the epoxy offer - I don't actually need much of the stuff very often. This was the first time I've even used 5-minute epoxy in ages. I had some that was only 30 or 40 years old, stored in the basement, and gave that a try. You can guess how well it cured. It's now gone.

Dave

 

[David Paule]

I used 5-minute epoxy to glue those foam strips over the exhaust pipes on the lower cowling. The glue was foam to cowl, not to the exhaust, of course.

With the lower cowl off, it was time to play with the #1 cylinder forward baffle. This is the one with the oil line to the governor. The constant speed prop I intend to get for this airplane is causing a lot of hassle, sure would have been simpler to plan on fixed pitch. Wirejock sent me a photo of the slot in his to allow for the oil line and I decided to do something roughly similar. His slot was from the aft side to the access hole. Mine was from the inboard edge to the access hole. You can see the support bracket almost hidden underneath.

In place without that bracket. Eventually I'll use #6 screws there, same screws as for the seat pan.

Not shown, I need to make a removable cover to block the slot I just made after installation. Wirejock avoided that; his is a more straightforward approach. Mine is easier to install.

Oregon Aero sent the seat cushions back to me for another trial fit. Looks like one more round. This is very much an iterative process, at least for this seat. Granted, my seat isn’t quite stock:

a. The seat bottom is flat instead of recessed.

b. The bottom of the seat back is slightly forward of the stock position since I have short legs and like to slouch.

c. And finally, this airplane has a decidedly non-typical crotch strap mount.

Since the plane has a manual flap handle on the left, the seat cushion has to allow for that. I’m not going to include photos showing the current mis-fit situation since I don’t want to give you the wrong impression. It’s fairly close, all but a few details.

With the seat temporarily in place, I needed to check the head to canopy clearance, so I brought the canopy home from the hangar. Here's what it looks like right now. Sure would be good to have enough more space to put the tail on. And the wings, too, as long as I'm dreaming.

Dave

 

[rockitdoc]

One Wing at a Time?

Maybe one at a time?

 

[David Paule]

Can't line them up for sweep that way.

Dave

 

[rockitdoc]

Can't line them up for sweep that way.

Dave

My issue, also.

 

[David Paule]

After sanding down the exhaust fairing foam, I taped it using packing tape so the fairing itself would release. The tape was placed in a way that bridged some of the poorly-sanded areas.

Then I laid up the three layers of glass and, just to make sure they wouldn’t fall off since I was working upside down, taped them in place. Duct tape releases too, on both sticky and smooth sides.

Here they are on the cowl, with the cowl on the bench, before trimming.

This shows the contour from the aft side. The cowl has not been trimmed yet.

I replaced the cowl on the plane and held the fairings in place. Turns out that there is insufficient gap between the fairings and the exhaust. Okay. That was all a good exercise and demonstrated a satisfactory approach to making the fairings. Now to go add some clearance and re-do them.

Dave

 

[David Paule]

Sorry for the hiatus!

On the re-do, the third left exhaust fairing was fine. The third right one wasn’t quite the way I wanted it, so made a fourth one, which was fine. Here they are held in place with magnets.

And

More recently, they are now glued on, and I’ve trimmed to fit and added the glass over the joints.

With the Oregon Aero seat cushions arriving again for a fit check, I was able to recheck the throttle, and sure enough it was too high. I shortened it and to do that, needed to shorten the manual trim lever, too. The PTT wires aren’t yet hooked up and the covers are still off.

Interestingly, when I sat in the cushions, the canopy was quite close to my desired head clearance. But after half an hour or a little more, the cushions had compressed a bit and then there was too much clearance. I'm looking for two inches, head to canopy.

I got the McFarlane throttle cable out so that I could start prepping for that installation, and learned that the threaded end isn’t long enough for a jam nut. On the other hand, it has a locking element. In the photo, it’s the red blob.

Now that the exhaust fairings are on, I decided to attempt to trim the front baffles. This is a bit of a conundrum, since I couldn’t put the lower cowl on with them in place untrimmed, and couldn’t mark them without the cowl in place. Russell Thomas was kind enough to offer some tips and ultimately it only took an afternoon. Here are the before and after photos.

And

https://i.imgur.com/KfE9pWR.jpg[/IMG

While I was checking the seat cushion fit, I took this photo. Clearly there’s some work ahead.

[IMG]https://i.imgur.com/bXBjfC4.jp

Dave

 

[David Paule]

I haven't been posting more regularly, sorry about that.

Lately I’ve been working on the baffling and the third seat cushion trial. The seat cushions are getting fairly close now but we anticipate a fourth fitting before the upholstery is applied. Oregon Aero sent me a generous sample of the sheepskin since that’ll affect the heat to canopy clearance and a few other smaller things. The sample they sent is about the nicest sheepskin I’ve ever seen. It’s very impressive.

I was able to lay one piece on the seat cushion and another on the seat back cushion and try that out. There were some differences compared to sitting on the same foam without the sheepskin, as you’d expect, but overall a rather significant improvement. Unfortunately the black samples they sent don’t photograph well. It’s too flat and unreflective. Imagine a black hole and that’s what the photo would show.

My initial plan was to have a Navy blue upholstery but after playing around with the black samples, I switched to that.

The front right baffle has a hole for the prop control oil tube. I made an access slot so that I didn’t need to remove the tube if I wanted to do something to that baffle. Here’s the hole in the baffle.

It needs something to fill its slot up and block the air gap, so I made a simple .016 cover attached to the support that screws to the engine.

Here’s how they go together. I’ve had that baffle on and off a few times since. Yes, the grommet isn't in yet - I know.

The two front baffles needed conical-shaped fillers to blend the outboard corners of the lower cowl’s air inlets to the baffles. When I thought about that I realized why the baffle plans had mentioned something about curving the side front baffles inward a bit. Unfortunately I realized that after I’d made the flanges that connect those side baffles to the front baffles, and it was too late to bend them in. What to do?

Now that I’d unfortunately built in a bit of a gap between the outboard lower cowl side corners and the side baffles, I decided to replace the conical filler pieces, which were aluminum, with fiberglass. Here are the female molds in progress. At the moment they are a little closer to being used.

At that point, with epoxy curing, I got involved in stripping vinyl and deburring the baffles.

=======================

Okay, moving right along, kind of hate to bring this up…. It’s beginning to look as if I’ll be too old to get insurance for this thing when it's done. If I can get liability insurance, that’s good enough, but I’d prefer hull too. If I can’t get at least liability I’ll sell it before flying it. I think that’s still probably two or three years off. For quite a while I've answered the common question of “when will it be done” with “three more years,” although that's just a wild guess. Anyway, I’ll be closing in on 80 then. I’d always planned on selling it but hoped to fly it first. Now it’s starting to look as if that’s not going to happen. Sure is a good project, though, so I’ll continue for now. But I wanted to let you know what the outlook is. I'm just too dang slow.

As I said, though, I'm continuing on course for now.

Dave

 

[David Paule]

Those conical filler parts are ready for installation.

And

The No. 3 cylinder has a spot that needs a bit of a bypass due to poor cooling fin design. Some bypass methods are to simply stick a washer in for spacing, other people make fancy devices. Here’s mine. It took some figuring and thinking to get it in the right position. The position might not match other builder’s installations but please remember this is an RV-3B and it’s often different. Wouldn’t have thought so for this sort of installation but this position is correct for this airplane and engine.

And in the front,

I got one of the ignition holders in, the one on the right side. Also, you can see some of the semi-trimmed baffle seal retaining strip templates being fitted.

The screws have nutplates, and while it would have looked cleaner to have the holder behind the baffle, this is a lot easier to remove if that should ever be necessary.

Haven’t done the left side yet. The baffle seal retaining strips are nominally 3/4” wide and in some areas as shown here, somewhat narrower. They will need to be thicker than the standard .032 in these areas.

I bought some of McFarlane’s “Cowl Saver” baffle seal material for this. I chose that because I rubbed a sample of it, Van’s standard baffle seal and some red silicone baffle seal against some of the fiberglass cowl, the lower friction of the "Cowl Saver" was very obvious. Also, I'd used the red silicone on my C180 and it just isn’t lasting as well as I’d have hoped, plus it’s clearly wearing the cowl. I plan to replace it with some “Cowl Saver” one of these days.

Dave

 

[David Paule]

For what it's worth....

As you may recall, I like this project a lot but don't have much of a desire to finish it. That's changing. I found a worthy follow-on project that's sufficiently appealing that it tends to encourage me to get on with things. The angst of completion has gone away.

We'll see whether that affects anything in practice. I could just find the next one too distracting, after all.

In case you're wondering, the next one isn't an RV. Or anything at all close.

Dave

 

[PaulvS]

Hi Dave,
Also for what it's worth... I hope you will be able to finish it, if for no other reason than you've got a lot invested already.
Some people start and finish in the same calendar year, I don't know how they do it. I'm slow too and more haste=less speed, it seems.
Cheers
Paul

 

[David Paule]

The plan is to finish, get it flying and sell it, if someone will buy it the colors it'll be. If I don't age out first.

Dave

 

[David Paule]

I decided to paint the conical spacers before installing them because it was easier. I used Stewart Systems. First I primed with EkoPoxy primer, sanded, filled a little, and reprimed. When I was satisfied, I top-coated with their EkoCrylic, in Firethorne Red. Right now they are drying. My intent is that the fuselage will be this color.

I had to tape the cones to some cardboard to keep them from blowing away.

For those of you who are aware that Stewart is out of EkoCrylic (June ’23), they still have some in 8 oz. packages, which is plenty for this.

The seat cushions came back for another trial. They are very close now. I sat in the plane for a total of three hours this weekend to be sure. Turns out that a mere hour isn't enough, when it's close.

Outside of these things, I’ve been busy with non-RV stuff like getting the C180 through its annual inspection.

Dave

 

[David Paule]

A close look with them now dry, shows a few pits in the paint, not exactly pinholes but similar. The epoxy primer I'd used under the red is white. Turns out that there is insufficient contrast for me to detect this sort of flaw in bright sun.

For me, the take-away is to use gray primer on fiberglass, correct any defects, and then a coat of the white, followed by the red. When I finished the inside of the canopy frame/fairing, I could readily see defects in the gray.

Besides the cowl, the canopy frame/fairing (which you'll remember is one piece) is glass, and later, the tail fairing will be, too. These little cones managed to jump to the front of the line.

Dave

 

[Dan 57]

Dave, finally managed to read your construction blog in its entirety. Read like a good book to me
Also brought back plenty of memories of my -4 build, very similar chains of problems to solve.
Thanks for that!

PS
I recall a pretty fit fellow during my visit, and sincerely wish you’ll be able to do as desired, best.

 

[David Paule]

Here are the cones installed.

And

I admit I'm not the world's greatest painter.

The baffle seal strips will include keeeper rivets for these, as they are currently only bonded on.

Since then, I’ve been working on the baffle seals, using McFarlane Aviation’s brand of material. It has considerably lower friction than the colored silicone or the black stock material. It’s easily identified either by touch on the black side or by the other side, which is gray. Part of the job are the baffle seal retainer strips I made. You can see them at the lower edges of the seals. I expect that as the cowl goes on, I’ll need to tweak these a bit here or there.

The McFarlane seal is gray on the pressurized side and black on the cowl-adjacent side. It needs to be scored to make it more compliant.

Since this photo, I have the top cowl on and will give it another day or so before removing it, to allow the seals to fully conform. Don’t know if this is necessary or not, but it can’t hurt.

Dave

 

[David Paule]

The seat cushions finally arrived. Right now they have more time and miles traveling than the airplane does. They went back and forth to Oregon Aero from Colorado four or five times, I think, each time getting a little closer to being comfortable. Now they are fine - thanks, Oregon Aero, for sticking with it!

There’re no photos of it because it’s black sheepskin in a dark gray cockpit and that’s as close to an unreflective surface as I know of. It doesn’t photograph well enough with my skills to include here. Anyway, you’ve seen photos of sheepskin seat cushions, so there’s not a whole lot of new information to be presented.

I finally got the front baffle seals of the lower cowl in place. The photo shows the left side. The right side is a little different but roughly similar. With considerable difficulty, I installed the lower cowl. I needed to work the baffle seal up over the front baffles and that wasn’t easy at all. Since I’d never done this before, it was a learning exercise as much as a fitment check. Now that it’s on, the baffle seal is ripply and doesn’t fit well, especially on the corners. I’m clearly going to need to do some modification, once I figure out what to do. The figuring out of things takes more time than the doing of them. I did succeed in getting a 1/2” overlap as intended. There’s gotta be a better approach!

Part of the delay was needing to order some more baffle seal attachment screws. The baffle plans call for AN507-6R8, which are 6-32 flat-head screws, 1/2” long. I ordered some NAS514P632-8P screws, and a size longer and shorter, to be prepared. They finally arrived. These are 125 ksi screws. Should have gotten 160 ksi ones but these should do fine. Turns out that the 1/2” length is quite right. I used nutplates where the aluminum strip was flat enough and the AN365 nuts where it wasn’t. Either way, the 1/2” length worked.

As I’m certain you’ve observed, I seem to have slowed down considerably on this project. Several reasons, mostly having to do with that intrusive thing called “life.” You all know about those sorts of things. Coming up, the high school RV-2iS project that I mentor is starting up, and I’m the only adult mentor this semester. The class time got changed and now it’s much less convenient. Plus I seem to have an unrelated steady but fortunately very part-time job that I enjoy very much but which being physical, is rather tiring at my age. So that’s a time impact that sort of falls into the “life” category. I guess I can guarantee that this airplane isn’t going to fly this year. But I’m still working on it, and will post here as I can. Stay tuned!

Dave

 

[David Paule]

This baffle seal project has been giving me fits. Once I got all the baffle seals on, using clecos to attach them and their backing strips, the top cowl became surprisingly difficult to install. The McFarlane baffle seals didn’t want to conform to the installed shape, bent to fit the top cowl. Yes, I have their scoring tool, which works well, and have been using it. I had to use a cargo strap and wait overnight to proceed. This wasn’t acceptable.

I couldn't rivet the baffle seal strips to the baffles like this.

I still have the original roll of Van’s baffle seal material and can install that if necessary.

I went down to my hangar because Ive got a roll of red silicone baffle seal there. I figured that I could at least give that a try. When I got to the hangar, apparently I misplaced it. It wasn’t there. Came back, heck, the round trip was only an hour. I'd hoped that a fellow with an RV-4 would be there so I could see some details of his, but no joy.

Had an idea…. Maybe the McFarlane baffle seal material can be trained.

I got into my bag of clothespins and am using those to hold the baffle seal bent over. I'll leave it a while and take them off and see how that goes.

I'm at a standstill until these are fixed. Any suggestions?

I did narrow the baffle seals and that made the problem worse... originally, several of the seals were quite ripply when the top cowl was in place. I thought of splitting them but decided that they'd improve if I shortened them. I reduced the overhand, above the baffles, from its original 1.5" to 1".

Dave

 

[Kyle Boatright]

I don't know about the McFarlane material, but when I've used thicker baffle seals I've seen the same issue. I really like the Van's material.

 

[David Paule]

Thanks, Kyle!

Dave

 

[rockwoodrv9]

I think I have a roll of the baffle material if you want it. Let me know and I will try and find it tomorrow.

 

[David Paule]

Thanks, Rocky, I have one that I'll use if it comes down to that. I appreciate the offer!

Dave

 

[rockwoodrv9]

Thanks, Rocky, I have one that I'll use if it comes down to that. I appreciate the offer!

Dave

If you want to do a plenum maybe we can use mine for a mold!

 

[David Paule]

Thought about that but haven't gotten to that point yet. We'll see, thanks.

Dave

 

[wirejock]

Plenum

Thought about that but haven't gotten to that point yet. We'll see, thanks.

Dave

Keep me in the loop too. If you want to layup a plenum, I always wanted to try my method and document for an article. I know one person who did it and it came out nice.
I may try it someday.

 

[David Paule]

Larry, will do, of course, but have no current plans to install a plenum.

Dave

 

[David Paule]

Just a quick update.

The baffle seals from McFarlane Aviation, which indeed are very low-friction, are simply too stiff. I could not get the upper cowl back on with any consistency. I removed them and made a set using Van's baffle seal, which so far (not done yet) seems to work fine. No surprise there.

Right now I'm not happy with the area at the front inlets that spans both the top and bottom cowl. I've got a scheme to try to resolve that and when I get some time (yeah, life interferes sometimes) will implement it and will let you know how it worked out.

Dave

 

[David Paule]

I finally gave up on the baffle seals preventing the top cowl from going on and seating. I could not get it to go on without using cargo straps - clearly not acceptable. I removed all the baffle seals and tried it. The top cowl went on fine. Then, one by tedious one, I replaced the baffle strips and tried again. Finally, using Van’s baffle seal material and some minor tweaking and a few judicious slits, not shown in this photo, the top cowl goes on without any swearing. And also without using cargo straps, which are back in storage, thankfully.

This photo shows some baffle seals on and others off, in mid-effort. Right now I'm using Van's baffle seal material.

Deciding to leave the top cowl on overnight to encourage the baffle seals to take a set, the next thing was to figure out how to make an inspection hatch on the left side, roughly similar to the oil door. I drilled a 1.5” hole in the approximate door location to access the inside and verify that location would work. Then I marked the location and used packing tape for a mold release, and laid up three layers of BID fiberglass for a mold for the future cover. Since the hole is in a section of honeycomb cowl, I couldn’t simply re-use the cut-out surface.

While I was getting this photo prepped for VAF, I saw that epoxy at the bottom left of the mold and went to the shop and wiped it off. Sure glad to get to that now rather than after it had cured. If the plane was in the hangar, 30 minutes away, it would have cured before I got out there again. Good to have a place to work on it at home.

You can see my trial hole through the green fiberglass.

I took about one minute, perhaps two, and did something I should have done long ago: I marked the battery and starter contactor so I can tell them apart. While their relative positions make that moderately apparent, clarity is always desirable.

Dave

 

[David Paule]

Last episode, we saw the fiberglass mold being laid up for a carbon cover. Below, you can see the completed mold as the green thing at the bottom of the stack. The black stuff is the actual carbon for the hatch, all two plies of carbon BID. It has an ugly white overlay, and that’s the peel ply.

It may have an eventual very thin glass layer where the hinge goes inside. Right now I haven’t made the hole for it nor the inside lip to support it.

When the hole is done and the hatch is shaped to fit - it had better fit - then I’ll decide which edge to hinge. If it’s at the top, it’ll be a lot like the oil door and the fasteners will be convenient. If it’s in front and I leave it unlatched, then it might open part-way in flight; I’d expect that would add cooling, at the expense of heating the canopy. Nothing’s free.

If I hinge its aft edge and accidentally leave it unlatched, it’ll blow open and might even blow off. Even if it stays on, it’ll be a flag advertising that yes, once again I screwed up. And no, I can’t see any reason at all to hinge it at the bottom.

Here’s the hatch opening. None of the extras are in yet; the recessed lip, the tapered honeycomb, the hinge or the latch. But the opening itself is cut. It doesn’t extend down into the cheek the way the oil door on the right side does, mostly because on this side, there’s nothing there to check.

Why two doors? Good question. One answer is that I was never comfortable with inspections done through a keyhole, which the oil door appeared to me. The FWF area seems a bit more open this way. Another is that on my non-RV airplane, there are two rather sizable hatches in similar positions, and upon shutdown, I open them for better passive ground cooling. That helps keep the overall thermal cycling relatively moderate, and more importantly, has eliminated the likelihood of vapor lock upon start-up, which had been a problem. In the hangar, an open cowl door tells me that the plane hasn’t been preflighted, while closed ones assure me that it has been.

In other exciting news, I’d been fretting about how to fix the mild height mismatch between the left inlet and the front left baffle. The baffle is slightly higher than the lip on the inlet and the baffle seal, attached to the lip, would not lay fair on the baffle. I’d been thinking that I needed to somehow lower the baffle. Unfortunately it is now an assembly and does not lend itself to that sort of rework. So what to do…. raise the bridge or lower the river?

I decided to raise the cowl lip since heck, I’ve got glass and epoxy out now anyway. I used 5-minute epoxy to stick a piece of foam in place and carved it to shape. That’ll be the form for the new lip.

Dave

 

[David Paule]

I trimmed the rough blank of the left-hand cowl hatch door and then retrimmed the opening so that it fit. Here, the door is taped in position, flush with the cowl.

Since the tape allowed for some positional variation, I used Popsicle sticks and 5-minute epoxy to stick the door in place.

When it’s time to remove them, the sticks will either pop off or be ground off.

And that’s it for this episode.

Dave

 

[David Paule]

Got to thinking that I should check my baffle kit for the laser-cut parts. Turns out that ordering these well before needing them paid off. The kit was from May, 2008 and none of the laser-cut parts seem to be prior to 2022. So apparently there are none, with the possible exception of replacement parts. Unfortunately the five replacements may well be. However, none of them are on Van’s parts list as currently published.

The hinge on the new engine compartment door is the same COWL-00005 hinge as on the oil door but the cowl geometry is a little different here. I found that everything worked well with a 3/8” thick shim between the hinge and the hatch. Seemed just a hair excessive, y’know? After I thought about it, I realized that this was a case of trying to raise the river; what also worked was the converse, of lowering the bridge. I chopped the hinge bolt hole off and redrilled them 3/8” lower and now it all fits fine.

Unfortunately I’d earlier tried trimming things and that just wasn’t working out. Now I’ll have to add on some glass and maybe some carbon.

The current version of the hinge no longer has a 3/16” hinge pin. Now there’s a bushing and it used a 1/4” hole in the parts. This gave me a choice: use AN4 hinge bolts or some of the Igus plastic bushings that I had on hand. Some of them were even the very same size as shown in the RV-14 plans, fortunately, permitting AN3 bolts. And also permitting another of the McMaster torsion springs, p/n 9271K268, that I’d gotten previously to give the door a resting position that’s open, so I don’t need to make another order there.

There’s merit to ordering parts and getting extras and hanging on to them, as long as you can find them later.

Which brings to mind that I need another box of bins for parts. But there’s one impediment: I don’t have a handy place to put another box of bins. My shop’s too small. Plenty of places to stash it but not anywhere near the other parts bins.

I had the usual relocation of the cleco holes for the hinge as I’d had on the oil door, but only one relocation this time.

Dave

 

[David Paule]

Got the hinges on the left hand hatch.

Since I’d hacked a bit of the hatch and frame earlier, I built that back up.

And I decided that it was way past time to clear off my work table, which had gradually become filled with parts trays, tools, old tiny fiberglass forms, epoxying stuff and even some old engine parts. All either tossed out or put away.

I’d lately been working on the cowl area around the spinner and the adjacent baffle seals. Since I was still using a loaner cowl front support, I lined up the aft cowl attachments (about a year late, but still...) and side connections and removed the support. It’s no longer necessary. Thanks, David!

The main thing I was doing on the cowl was developing the attachments for the upper and lower cowl at the spinner, on the inboard sides of the cooling air inlets. I’d originally planned to use piano hinge there but concluded that would be operationally difficult since the baffle seals were right there. I needed to make a glass or aluminum lip from the bottom cowl up to the top one, and botched it. It needs to come off and get redone.

Dave

 

[David Paule]

With the glass-work complete connecting the upper and lower cowls at the spinner, I drilled them for the nutplates. Then I drilled the cowl side laps for their nutplates too.

Before I can actually rivet anything to the cowl I need to finish the interior. That’s a job I’m not looking forward to, but it seems to be coming anyway. Also, I need to finish the hidden latch for the left cowl door.

Dave

 

[David Paule]

Those cowl nutplates are installed and the top cowl got painted with neat epoxy, prepping for the white inside paint. Here are the photos below. Both cowl halves are resting on the box to my Zizzo Urbano folding bike. It makes an excellent cowl rest.

There's still a fair bit of work to do before painting it, and I expect that'll need to wait till later - see below.

Note - this is my first effort posting photos to the new VAF format. The procedure is different but simpler: Click on the photo button above the edit window and select the photo you wish to post. That's it.

========

Folks, I'm two weeks away from surgery for something. It should only keep me away from things for a few days and it's unrelated to any previous issue. The prognosis is generally favorable, and I'm not worried.

However, as much as I enjoy this project and am working on it, and will continue to work on it, it's more and more evident that I'll never get to fly it. I'm just aging out. It's premature to sell it but on the other hand, sooner or later it's going to get sold.

I've been working on it for day VFR usage, primarily cross country, but not acro. I intend to put the lightest-weight constant speed prop on it I can find. Currently that's a Whirlwind 300 series prop.

The only reason for mentioning this stuff now is that obviously I've slowed down on it, and it's time to consider the future of it.

If you have any comments or thoughts about the project (not my health), please chime in.

Thanks.

Dave

 

[RussellT]

Dave,
You are 99% done!

Firewall forward is fiddly and a bit awkward working within the limited available space etc on the 3 but it is straight forward.

You may not get to fly it but I do think that you will get it built and see it fly.

Great work and best wishes as always.

Russell

 

[David Paule]

Just a note to say that the surgery seems to have done what it was supposed to, probably, I'm recovering from the surgery now but still haven't gotten back to work on the plane. That's mostly due to the fact that I still have a bit to go for recovering and my activities as well as my attention span are limited. But there's progress there, if not on the plane. I'll report more when there's more to report, especially about this -3B.

Well.... a tiny smidgen of progress and evidence that at least I'm thinking about it. I had planned to install a sump pad heater and have one on hand. I bought one of Anti-Splat's sump heaters and believe I'll install that instead. I think it'll be a tad more efficient.

My experience in the last few years with my C180 is that if it's cold enough to need the engine heater, it's too cold to get me to go out to the airport to go flying. But the sump pad heater on that plane is useful for oil changes. Back when I did use it to go flying on cold days, I'd go out the evening before, plug it in and leave it on until the preflight was done. The airport's a 25 minute drive one way, depending on traffic. Incidentally, the sump pad heater on the C180 has been there for 25 years and probably around 700 hours or so and has been reliable.

Stay tuned to this station!

Dave