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RV-3B Dave's in Colorado

I caution anyone using your wife’s stove to dry or bake painted objects to ask her first and tell her it might “smell” for awhile. I did not. It works great but when I finished the whole house and especially her kitchen reeked with paint odor. She came home about five minutes after I finished. I got that “your in big trouble look”. That was about 20 years ago and I still hear about that😳

Bob Grigsby
3B. Close. I think
Flying Cub on New Years
 
I've been letting things dry normally until they are dry enough to handle, and then baking them. The smell is markedly reduced.

Also, my kitchen has an external exhaust fan so I can clear fumes well.

With those two things, it's a non-issue.

Some of you might have seen that the urban fire is near me. I'm unaffected by it although it's very close. I know people who had to evacuate; some returned but not all. I don't know how they fared. We had 105 mph winds after an extremely dry year. Fortunately the weather changed and now the wind is nil and it's snowing. Tomorrow will be in the teens and that too helps fight the fires.

Happy new year, everyone!

Dave
 
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Dave,

Where did you get the Tail Lynx cables and springs? They look very nice and streamlined. I did a search and it looks like Vans sells them. However, I can’t find them in the Vans store.

Thanks
 
I bought them from Van's back when they still made them.

My general policy on this project has been that if something is made by a small vendor, buy it early in case they go out of business or retire. These fell into that category, as did the Vetterman exhausts and the Robbins Wings cabin heating parts. There were probably some others.

Dave
 
Before I started drawing up wiring schematics, I had to make some fundamental system architecture decisions. I wrote down my thoughts at the time, and have been doing the system work based on that. I came across this in my notes and thought it might be worth including.

My goal is day VFR. Big caveat, I am not including an upgrade path to eventual IFR, although I will incorporate ADS-B compliance as part of the initial installation.

1. My ignition uses self-powered sources (can be magneto or P-Mag, with P-Mags installed) and is redundant. With the same equipment on both left and right, though, these are similarly redundant, not as good as redundant by different means.

2. The fuel pumps are redundant, since there is both an electrical and a mechanical one. These have different modes of failure.

3. The fuel filter, a gascolator, is a single-point failure mode in series with the pumps. It's located inside the engine bay inside the thermal and fire envelope of the region.

4. With both the standard air intake and a carb heat system, the engine will have separate sources for intake air.

5. My basic electrical power source is redundant, with both a single alternator and a single battery. These are differently redundant but are connected to the same systems and connected to each other, with interconnected modes of failure.

6. Navigation will be differently redundant too, with an iPad primary and the EFIS secondary. The iPad has its own battery and in normal operation will be charged from the aircraft. If the power fails it'll retain several hours of power itself.

7. The airplane will have minimal basic lights and will be marginally capable of night flying. The main purpose of the lights is for daytime mid-air visibility. Night flying goes beyond my planned operations but the capability adds contingency operation. In-cockpit lighting will be with a headlamp.

8. The airplane will have an analog airspeed indicator. I feel that I can judge altitude over the ground well enough to stay safe if the EFIS dies, and there will not be an analog altimeter.

9. The airplane will have a stall warning system much like my current airplane does. It's a single-point angle of attack indicator. If electricity remains, it should function. It's a back up and an assist to the EFIS or analog airspeed indication.

9. I think all else will be non-redundant.

10. I will only have a single com radio, a single transponder and a single ADS-B system. That should let me get back home to my non-tower field.

Dave
 
Okay, you could be thinking, I closed earlier with a shop reorganization and then jumped straight to the panel installation, and then went rambling. What the heck? Well, the EFIS arrival let me do some more electrical things and some of them, like the canopy latch warning switch, the wing electrical connectors, and connect to the EMS once it's located, which is part of the engine installation. While the shop still has electrical tools and parts handy, it made sense to work on that aspect.

One of the things I did was revise the warning light wiring for the third time. It just wasn't right, to the point that I'd rip it out and redo it. The version shown has bene redone.

I rather hate to mention upcoming things - I much prefer to talk about things that happened. But one of the things that happened is a rough plan for the engine and shop. So here is a brief look ahead.

* Get as far along with the panel and electrical as I can without the engine.

* Bring the engine home.

* Install what I can on the engine before hanging it.

* Locate the firewall holes and drill those. Make the Fiberfrax and titanium overlay and install those.

* Finish the shop reorg. Can’t do it earlier because I need the current layout to work on the engine before I hang it. And I can’t go farther until it’s reorganized. This is one of the things driving the sequence.

* Bolt the engine mount and landing gear on. At that point, the fuselage can’t be easily flipped on its side or upside down without help.

* Install the engine and complete its installation, including the remaining electrical.

The bottom of the switch panel needed a few things, like the P-leads to the ignition and so on. I opened up the avionics shelf to have access. This is also letting me tie up the wire bundles. I took the opportunity to label the switches from underneath to make identifying them more sure next time. The photo was taken just after opening it up, before the labels went on.

It was easy enough, unfastening it and rotating it clockwise 90 degrees and laying it on the sawhorse. Once the wings are on, it’ll open 180 degrees and rest on some sort of a support.

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Off topic - I live in Boulder, CO and sometimes manage some rentals. The recent Marshall fire did not affect my home or the RV-3B project, but it did affect several of the rentals. All survived and the people are fine. But smoke clean-up is on-going now, and dealing with that has been affecting my work time. A number of people locally were affected, and about 1,000 nearby homes were lost.

One of the things pending was to locate the ground tabs and the Dynon EMS. The ground tabs are easy: with the battery fitting into the right cowl cheek extension, the ground tabs will go inside the cabin at that point, high on the right side cockpit wall. But there wasn’t room for the EMS and it’s thick, stiff cables. There were three locations that I narrowed to two. The location that didn’t make the final selection was the back of the panel on the right. The EMS fits there nicely but that location would preclude using that half of the panel for anything that wasn’t surface-mounted. The panel is too small to accept that limitation.

The above photo shows one of the two final candidates, the bottom of the avionics shelf. This location has a few issues, too. Among them is simply that my knees are right below it. Another is that either the carb heat or the cabin heat cables will pass through the area.

j9nfQ9M.jpg


The next photo shows another of the two final candidates, the top back of the firewall. This would interfere with some of the firewall-mounted stuff, since it’s the only firewall area free of the engine mount complexity.

Any suggestions?

That fiberglass tab on the right of the avionics shelf will hold a large snap bushing for the EMS network cable, the ground wires and the power cables. It's one of the things that's been going in.

Dave
 
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I went ahead with the EMS installation on or rather, off the firewall. The fittings support it a little over 3/4” from the firewall; I’ll be able to install components forward of the firewall at that location with a bit of paying attention to things.

3f2SgYo.jpg


The sensor cable will go out the righthand cowl cheek extension and the network cable will need to somehow wrap around the EMS and go to the avionics shelf via the right side.

The pitot tube from the left wing is 1/4” plastic tube, pretty standard stuff. Then I switched to 1/8” plastic tube and this is much easier to work with. However, I didn’t want to replace the tube in the wing so I needed a way to reduce the 1/4” tube to 1/8”. Since the tube to the ADAHRS and the tube to the airspeed indicator all meet in the same area as the 1/4” tube, some sort of fitting was needed.

This photo shows my two choices. The blue fitting with the tube connections weighs about 34 grams, and the plastic fittings collectively weigh about 11 grams. This was a no-brainer; I’m using the plastic.

ELzH9sd.jpg


I made a list of all the grand connections that the ground forest of tabs will need to accept. I already have the forest of tabs and it ought to have ample tabs. Three seemed misplaced but with a bit of thinking I found two of them, and then by digging, I found the third.

The after-market network hub by Gil Alexander is pretty nifty, but the plug-in Molex connector hadn’t checked out. It was the only thing that hadn’t. With some time, I replaced and reset the pins in it, and now it all checks out. Incidentally, that hub contains the ground and power leads from the servos so they don’t need discrete hookups, a definite convenience.

I sort of enjoy working with standard Dsub fittings but Molex connections are a real pain. And I have another unrelated one to go.

Dave
 
The electrical wiring is as far along as I can get without installing the engine. Every wire has been checked and tested. All the cables except for the EFIS 37-pin cable, the CHT/EGT cable, which are both factory-made and the cables already in the wings . The cables permanently attached to the fuselage have been checked and tested. Since the ground forest of tabs is not yet installed, none of the electronics can be connected to power yet.

Ryan Courreges, climbak here on VAF, had offered to help with the project. He helped with the car shuttle to get the engine and engine hoist home, thanks, Ryan!

UTN3T1n.jpg


Once we got the hoist reassembled and rolled the engine into the shop, we found a possible difficulty that I hadn’t anticipated. The hoist’s legs would not fit under the work table, and that meant that the engine would not go over the table. We moved the hoist around to a corner and that let the legs straddle the table and get the engine a bit closer. After rotating the engine we got one support on the table, Ryan supported the other side as I let off the hoist and then we slid the engine on the table.

7FiNtIl.jpg


The first thing I found was that I’d lost the oil pressure restrictor. But I seem to have most everything else on hand. The new shorter dipstick tube arrived and I shortened the dipstick to suit. RV-3s and RV-4s have a tighter cowl than the other models and need the shorter dipstick tube.

One thing that’s very apparent with the motor on hand is that this is a really small airplane with a big engine. Up close, it’s an impressive comparison.

Waiting for parts, I did a few things in the cockpit area - now the EMS network cable is guided by Adel clamps, and the rudder springs are finally installed. The rudder springs aren’t part of the plans but some builders add them. I finally figured out how to terminate their forward end without adding any new parts: I drilled holes in the center ribs for the ends. Simple, no parts and removes weight (every so slightly).

Dave
 
The baffle kit is sort of a fill-in right now. It’s in progress, and I’m accumulating a number of drilled, deburred and ready for assembly parts. I need to get the finish on them before that, though.

One of the things that’s much easier to do with the fuselage flopped over on its side is finishing off the mixer fasteners. I installed the grip on the control stick and bolted it to the mixer, and the mixer to the fuselage and elevator pushrod. All move with no perceptible friction and no perceptible free play. I used castellated elastic clock nuts and cotter pins on all joints.

i1kfZUH.jpg


The stick grip, that’s the yellow tennis ball, is held on with three universal-head blind rivets. They are located so it’s the heads which act as stops for the grip. The grip is not riveted, screwed, bolted or bonded to the stick. It is secure, and I used a different tennis ball and piece of tube to the concept.

The dark cone in the photo just below the right hand EFIS knob is the work light I had in there. It’s not a flight part.

Next, it was time to attach the engine mount and dummy firewall to the engine. I only used two sets of the isolators for simplicity. The dummy firewall is .093 acrylic. I left the protective overlay on.

3ckKSvp.jpg


With the dummy firewall in the correct position with respect to the engine, it was obvious how little room there actually is between them. And the governor will present an interesting difficulty: the lever is aft of the plane of the firewall inside the recess (denoted by the hole in the dummy firewall).

Anyone have any ideas?

5iCEQOr.jpg


Another thing that I noticed was comparatively small potatoes - the governor bracket doesn’t fit this governor. Sort of doesn’t matter, though, since the firewall is in the way anyhow.

Now I can determine where I want to install the various firewall-mounted devices and where I’ll need pass-throughs.

Dave
 
Started installing components on the dummy firewall. This was fun work. I had to balance a number of issues simultaneously, like filter removal and the routing for the various hoses. As of now, the remote oil filter, the gascolator, the sensor manifold, sensors, oil reservoir are all located. None of the hoses are on order yet. The dummy firewall is proving to be a very good idea.

TwWpE9T.jpg


I had initially thought that possibly both the remote oil filter and the gascolator could get hung from the engine mount on Adel clamps but it turns out that they are sort of comfortable on the firewall itself. Access appears awful but is actually better than it looks.

One note - the Airwolf remote oil filter assembly comes with the CH48109-1 filter. This takes approximately an inch and a quarter to remove. The CH48108-1 filter is very similar, slightly lighter and an inch and a quarter shorter. So the longer CH48109-1 is a decent stand-in for the shorter filter. If the long one fits, the shorter one can be replaced.

I noticed that at least one of the parts of the Airwolf remote oil filter assembly was quite poorly deburred. Nicely anodized but they left a sharp edge in several places. Be careful.

It’ll need to be relocated slightly downward from the position shown, maybe 4-5 mm.

The new Dynon sensors are just a bit too fat to permit the manifold to be mounted in its normal mounting position. I made a small bracket that you can’t see in the photo and placed it on it’s side. The sensors are on the cabin side of the firewall where there’s excellent access. That frees up some firewall space and keeps the sensors where the environment is a bit more benign. You can see some of the sensors on the dummy firewall, and some of the fittings might get changed.

j0TkkvT.jpg


Looking around for a decent place to attach the cabin heat valve, and well, there wasn’t any. But I’d built the firewall recess to allow the standard oil filter to poke into it along with the prop governor. Since that Lycoming filter adapter got replaced with the remote one, there was some room in the top of the recess, close to the aircraft centerline. It turns out to be a good location. You’re probably thinking that access will be awful but with some judiciously-placed access ports in the recess, it won’t be too bad.

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Remember the governor lever is aft of the firewall? A worry. My mentor had a brilliant suggestion: route the control cable to it through the side of the firewall recess, just like the cabin heat valve’s control. Yes, I’ll need to spend some time with the access ports for sure. But doable.

When I shortened the oil dipstick, I had a stub left over. It was kicking around a workbench, looking like it really ought to be useful somehow. I’d thought it was stainless but it’s aluminum. Van’s sells several different colored round control handle balls and I had at least one of each on hand. Never know when they’ll come in handy…. A red one was fitted to the dipstick stub and now I have a great little brake fluid reservoir dipstick.

ZFcLLkT.jpg


Dave
 
Dave,
I've really enjoyed following your posts.
The dummy firewall is a ingenious idea.
I'm wondering about putting the Dynon sensors on the cold side of the firewall. A mechanical failure of a sensor could put hot oil or fuel in the cockpit.
 
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David, good thought. The latest Dynon sensors have improved mechanical strength and vibration resistance compared to the earlier ones, and the fuel and oil sensors both have restrictors in their supply lines. I think that the overall risk is low, and that there's at least some chance that if one does fail, it'll fail with a slow leak rather than a gusher.

And if that happens, my left foot will be in the puddle. At least it wouldn't be dripping on the hot exhaust pipes, as it would if I mounted it forward of the firewall.

Dave
 
I made a mount for one of the under-cowling temperature sensors and it weighed about 20 grams. The second one weight under 4 grams, so it was worth doing. Sorry, no photo of that, but it was made from a piece of 1/8” 6061-T6 sheet. This one will go on the warm side of the baffles. The other one will go on the cold side and I’ll hold off on their attachments until further into the engine installation.

After mocking up the governor control, it was annoyingly evident that there was no way I could run the control through the side of the firewall recess. I made a control lever extension to bring the line of action forward and while the extension itself was fine, it made the total travel become greater than the control cable’s capability, so that didn’t work. This left some sort of way to carry the cable into the recess while not having its support in the recess. Here’s a picture of the mock-up of something that works.

iPsswv4.jpg


No part of this assembly, except for the governor, is flight-worthy at this point, especially the hardware and the control itself.

One thing that was very necessary was to add some sort of access to the back of the recess. The access port started off well, using a 3/4” hole saw. The material is .020 grade 2 Titanium.

wasVYeu.jpg


But cutting the outline out proved to be probably one of the worst jobs so far on this project. Turns out that the only tools I could apply were a nibbler, which didn’t work here, and a cut-off wheel on a die grinder. Well, attempting to make a groove and work it deeper was totally the wrong approach. The titanium formed around the cut-off wheel and then hardened. The spray of incandescent particles hid the marked line. This did not work.

But cutting through and then running the cut-off wheel along the line worked well enough. However, I did go past one of the corner radiuses a little bit and I had to patch that. This whole cut-out was not a fun job.

Cleaning up the cut edge was equally enjoyable. My Vixen file did make progress, but at a microscopic rate, and even at that it took a lot of force to make any change. I tried a sanding drum on the Dremel and surprisingly, that proved effective. It ran through drums at an alarming rate but did the job. You can see the corner error at the lower right.

B3QILcY.jpg


Making this hole and the cover, not shown, took a day’s work session.

I later patched the corner error and added nutplates for the cover.

Dave
 
Nice work, Dave. However, I am curious how you fixed the cut in the Ti. Welding that stuff is pretty tricky, but if anyone knows how.....
 
Just riveted a patch on. Nothing fancy, Scott. Two -3 rivets on either side of the slit, and dimpled the holes.

Dave
 
After learning how to attach coax cable to the BNC connectors used on the Delta Pop antennas and the TNC connectors used on the Dynon transponder and Trig com radio, I figured that this would be a grand time to see if the antennas fit on the airplane and if the cables fit their respective components. To my pleasant surprise, everything fits fine. Still not sure how that happened.

The cables and connectors were another skill to learn, and needed the usual new tool. Thanks, Steinair.com, for the and the BNC video which made the learning curve almost disappear. The TNC connector goes on the same way but with different dimensions, which are given in the manuals.

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antennas above and below, the com antenna cable.

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Remember that I’ll need to fit the fuel tank vent lines around the com antenna cable. Thanks to my mentor for reminding me; I'd forgotten. That's the transponder and its cable below.

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All the engine control cables except for the throttle cable arrived. The throttle cable is a bit undefined since I can’t hang the carb on the engine just yet. This order, from McFarlane Aviation, included the

Prop governor cable,
Mixture cable,
Carb heat cable,
Cabin heat cable.

The first two are vernier-assist cables. The last two are basic Bowden cables. McFarlane sold me labeled knobs for these. The cabin heat cable goes through the firewall in the side of the firewall recess, so I drilled a hole for that, after first deciding how to fire-block the small hole. I’d had to ascertain that there’s enough access from the front of the firewall to install the cable on the valve. There is, but it won’t be a job that I’ll enjoy. Still, there's another way: remove the four cabin heat valve attach screws, which are inside the cabin on the recess, readily accessible, and then the valve can move around a bit for easier maintenance.

The stiffened governor cable attach bracket is ready to install now, too. I added a flange to stiffen it.

Here’s the Titanium foil overlay for the firewall insulation, with the Fiberfrax ceramic insulation that I’d previously cut to match the firewall resting on it. I’m in the middle of drilling holes in the foil.

PQK01P2.jpg


The thin Titanium was easy to cut with shears - I think scissors might work but I didn’t want to dull them - and the edge was not particularly hazardous. I deburred the edges with a fine mill file. The recess hasn’t been cut yet, one of numerous operations still pending.

Drilling holes up to 3/16” is straight forward. I used a step drill to drill one of the 1/2" holes and that did not go so well. Nice hole but a monstrous burr, which I filed down. I'll try a punch next.

Dave
 
Hole saws work well, but these are 1/2" holes and they are not readily available here in that size. The ones you recommended don't go that small.

Thanks, though!

Dave
 
I should have been more specific.
Standard ROTACUT 5/16" through 3/4" seven cutters.
https://www.browntool.com/Listview/tabid/344/txtSearch/rotacut/ProductID/355/Default.aspx
Large ROTACUT 7/8" through 1-1/2" six cutters
https://www.browntool.com/Listview/tabid/344/txtSearch/rotacut/ProductID/3222/Default.aspx
Master ROTACUT 1/4" through 3/4" sixteen cutters by 1/32" increments.
https://www.browntool.com/Listview/tabid/344/txtSearch/rotacut/ProductID/3221/Default.aspx
Brown Tool as an example, other vendors carry them too.
I have the first two kits and have found them superior to any other hole saw (although hole saw to me implies the cheap not quite round hole saws intended for woodwork) in terms of precision.
When I got the new nose gear (with suspension) and engine mount from Vans having already drilled the rod type mount, I found the hole saws perfect for the 3/8" (I think) holes I had to drill thru the stainless steel firewall and aluminum substructure.
 
Terry, thanks again for the suggestions.

I finished the 1/2" holes with a punch and the two 1 1/2" ones with a Lenox hole saw, bought locally. That's one task out of the way now. Can't say that the .005 Titanium is that much fun to work with, especially compared to the .020 Titanium which actually behaves, at least most of the time, like a real metal.

Dave
 
The firewall insulation went on after a lot of trimming and fiddling. At the last minute, I had to trim the perimeter back a little to allow for installing the quarter-turn cowl fastener’s mounting strips. And of course I had to trim the .005 Titanium overlay foil, too.

I used 3M’s spray adhesive #77 on the firewall to attach the insulation. It allows repositioning for a bit and then sets firm. I used it again for the overlay foil. Both of these required non-trivial positioning since I had only one real change at getting it right. One side of the foil came out better than the other, of course.

The recess area took the most work. The sides were integral to the main foil pieces but the top and bottom were add-ons. And the top back that went under the heater valve was a separate add-on. I had to do that twice after botching the 2” heater air hole the first time. Drilling holes in the .005 Titanium grade 2 foil is something that I find difficult, and I didn’t have a 2” punch. Here are some comments I made in DanH’s firewall thread:

It's easy to drill holes to 1/4" with normal drills. No problem at all.

Unibits, I use Harbor Freight's version, tend to leave a burr. They form a partial cylinder, a shot one, around the hole. The second-best way I've found to remove those is with a coarse mill file. The best way is with a Dremel sanding drum, which does it quickly.

I tried Harbor Freight's 95547 punch set and it was terrible. It did work for some 1/2" holes with a lot of swearing and some burrs, but wasn't worth the trouble. I recommend against it. The smaller holes made by my Whitney Junior punch work fine, but that has a short throat depth and so can't put holes everywhere they are needed.

Hole saws work okay but be sire to clamp the foil well!

All the stuff bolting to the firewall went on smoothly except for one small detail. I hadn’t allowed room for the brake reservoir tee to get installed - it hits a cross-angle on the cabin side. But I figured out a work-around, so that’s not a real problem, merely a detail. I’d made a test of the insulation to see if it takes a set under bolt pressure and learned that it most certainly does. I used the wide-area AN970 washers under the nuts and used the reduced shear fastener torque for all these.

When that was done, I bolted the engine mount on. All the four corner bolts were too short. I had the middle bolts in the right length and a too-short length, so I must have tried this before. Wonder why I hadn’t observed that the corner bolts also needed replacing…. Once the engine mount was on, I checked and sure enough, there was no way I could rivet the quarter-turn cowl fastener’s mounting strips with the firewall there. Off it came.

There was this detail… I didn’t need or want the mounting strips where the cowl cheek extension’s bulkheads were attached, and until the cowl was on, I hadn’t a firm position for those. But when I was working with the acrylic dummy firewall, I’d taken a line from the center of the rocker box covers to the dummy firewall and marked them, so I knew where the fat part had to be. Working from those located the bulkheads in a preliminary sort of way. My mentor had sent me some photos showing where the cheek extension was on his plane - thanks, David! - and my locations compared to his to about an 1/8” which is close enough at this time.

The photo shows the firewall overlay, less the FireBarrier caulk, and the upper cowl mounting strip. The strip needs scalloping in this photo. The recess was a bit tough. Oh, the brake reservoir is just hanging there upside down now, for convenience while working on that strip.

lrPA6G2.jpg


There are a few magnets visible near the engine mounting points, in case you're wondering.

Dave
 
I got the top and the bottom side mounting strips done, primed and riveted on. Years ago, I bought a set of Mil-Spec fasteners, not knowing that they’d go out of business leaving Skybolt as the main RV quarter-turn fastener vendor. The two products are substantially similar. These got riveted to the mounting strips and then the strips to the firewall.

The top strip was complicated by needing the nutplates for the forward fuselage top skin, which on an RV-3, is removable.

A decision I’d made back when I was skinning the fuselage paid off - I had not riveted the firewall joint to the side skins, relying on the G/flex epoxy for the joint. That decision paid off because the side strip rivets didn’t interfere with a previous rivet pattern. The riveting on the top was less fun than I’d hoped, partly because of the nutplates but mostly because of the firewall flanges.

wZw7pTe.jpg


There’s still some work needed on this, but most of it’s done. The cowl mounting strips are white merely because I only have white and gray primers right now, and the white is a relatively durable epoxy.

The bottom, in particular, will get a more finished look before too long.

Dave
 
I had to finish off the bottom of the firewall overlay, as you can see on the last photo in the previous post. There’s no bottom flange on an RV-3B firewall. I made an angle of .020 Titanium and used 3M’s 2219 B/A epoxy to glue it on, following their preparation recommendations. I chose 2216 because they offer strength data to 400 F, plus some useful documentation. This was delayed because I was waiting for some stronger magnets to come in to hold it while the epoxy cured. When they were delayed, I figured out an alternate support technique and that worked well enough. I used weaker magnets and strapping tape.

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After over 6,000 hours, it took less than four more to put a few parts on the fuselage. Then it was time for the requisite photo.

UWDGpdz.jpg


The next step is to deal with an unfortunate little weld problem I discovered on the engine mount that will probably require removing the landing gear and engine mount. My AI, who does the annuals on my C180, is coming by to have a look and discuss it with me. He’s helped me with this RV-3B before.

Dave
 
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Thanks, Scott.

The small weld issue mentioned above is an incomplete weld. It had the appearance of a crack but wasn’t, exactly.
I’m an old aerospace engineer and have done many crack propagation analyses, and felt it needed to be repaired.
Checked with my certified airplane’s AI, who said to repair it. So did my mentor, another engineer, and Van’s support. Actually Support said that this area might crack anyway at some point, repaired or not, but that it would be better to repair it.

It’s at the top of the right landing gear socket and is in that red circle.

sRaCEO2.jpg


After pulling the landing gear legs off and removing the engine mount from the fuselage (which I hated to do….) I removed the cadmium plating in that area with Muriatic acid. Some of you will cringe at this, but I did it in the kitchen sink, it being way too windy to attempt it outside. The stainless steel sink wasn’t affected by the few drops of acid that landed on it, and with the faucet going, there was ready dilution. My exhaust fan vents outside and is unusually powerful. I opened a window and got positioned so that the flow was window to me to sink to fan, and I was in clean air.

After an hour, the plating was gone in that area. The actual welding took no more than two minutes. I put primer over the non-plated areas, bolted it back to the firewall and reinstalled the landing gear. Done.

Since I hadn’t known when things could happen, I had a bit of spare time between the plating removal and the welding. I’d been working slowly on the engine baffles as fill-in projects. With the usual cursing, I was able to get the back baffle pieces in place. As you can see from the untrimmed top of the baffles, the ignition cable draped over the top, and the fact that the blue vinyl is still on and a couple other minor things, this is still a work in progress.

olrVrGv.jpg


Dave
 
The small weld issue mentioned above is an incomplete weld. It had the appearance of a crack but wasn’t, exactly.
I’m an old aerospace engineer and have done many crack propagation analyses, and felt it needed to be repaired.
Checked with my ferried airplane’s AI, who said to repair it. So did my mentor, another engineer, and Van’s support. Actually Support said that this area might crack anyway at some point, repaired or not, but that it would be better to repair it.

It’s at the top of the right landing gear socket and is in that red circle.

sRaCEO2.jpg


After pulling the landing gear legs off and removing the engine mount from the fuselage (which I hated to do….) I removed the cadmium plating in that area with Muriatic acid. Some of you will cringe at this, but I did it in the kitchen sink, it being way too windy to attempt it outside. The stainless steel sink wasn’t affected by the few drops of acid that landed on it, and with the faucet going, there was ready dilution. My exhaust fan vents outside and is unusually powerful. I opened a window and got positioned so that the flow was window to me to sink to fan, and I was in clean air.

After an hour, the plating was gone in that area. The actual welding took no more than two minutes. I put primer over the non-plated areas, bolted it back to the firewall and reinstalled the landing gear. Done.

Since I hadn’t known when things could happen, I had a bit of spare time between the plating removal and the welding. I’d been working slowly on the engine baffles as fill-in projects. With the usual cursing, I was able to get the back baffle pieces in place. As you can see from the untrimmed top of the baffles, the ignition cable draped over the top, and the fact that the blue vinyl is still on and a couple other minor things, this is a work in progress.

olrVrGv.jpg


I removed the baffles for the next step, in spite of being able to progress with this. It was time for something else.

Remember that the engine was on my work table. I’d made a crucial error building the table back in ’12; I hadn’t allowed enough clearance under it for the engine hoist, or even a floor jack. Wirejock (AKA Larry Larson) came by to help and so did mtnflyr (AKA Rick Brennan) to help with the engine installation. Larry hoisted the table, I shoved the jack under it and lifted, Rick stabilized the engine, and we maneuvered the hoist in place and picked up the engine. I’d moved the fuselage partly outdoors to get more room in the shop for this, so we put the engine in place.

With rather a lot more work than I’d expected, Rick and Larry got all four isolators, bolts and nuts installed. I certainly could not have done it by myself. Fortunately both guys had not only done it for their planes, they both offered to help me. I did very little; they were the installers. And I’m mighty glad that they were both here.

Thanks, both of you!

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They look a bit concerned because at this moment it was not going smoothly.

Once the job was done, they left, after posing for this job well done photo.

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Afterwards, I torqued the nuts and took this close-of-day photo.

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These guys saved my bacon more than once. Thanks again.

The engine’s on. Now there’s lots of things I can do.

Worth noting is that with the tailwheel on and about 30 pounds of weights on the aft deck, the plane is stable. When I raised the tail and it approached level, though, it was getting awfully light. Those weights are important.

Dave
 
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Friends

You have helped me more than I can account. This was the least I could do. Rick had the genius idea. The last bolt (bottom/port side) didn't want to cooperate. He used a pry bar to move the mount just a tiny bit and it slipped right in.
So happy we could help. Be well my friend/mentor.
 
Thanks!

Rick and Larry did the hard stuff. For me, mostly this just opens the gate to a lot more work... as you know. Kinda looking forward to it.

Dave
 
Cadmium plating ? On the engine mount? I doubt that Vans would do that on a tubular mount because of the danger's of entrapment of the plating solution in closed areas of tubing and because of hydrogen embritlement.
 
The cad plating was done by an aerospace plating company, which unfortunately is no longer in business. The engine mount was masked beforehand and baked afterwards, to prevent those issues. It was done per the relevant specs.

While I was there, I saw a number of other aerospace parts in for similar plating.

Dave
 
I decided to install the stainless steel fuel line from the firewall to the gascolator, only to find that it didn’t come close to fitting. That was one of the parts I’d made a pattern for while the dummy acrylic firewall was in place. In theory it should fit, but in practice it doesn’t. And that my friends, is the difference between theory and practice. However, other things which I fit the same way, fit just fine. It’s only this one part.

Incidentally, if you haven’t already installed the tiny screws for the tube fittings on an Andair device, do it before you install the device. You’ll be happier. I removed the gascolator, put in the screws and reinstalled it. Andair says to stake the screws and I didn’t do that - I used Permatex Threadlocker Blue instead.

You may have heard that there’s not much room between an RV-3 firewall and the engine. That’s entirely correct.

David Howe’s cowl tool is virtually essential for aligning the cowl. Wirejock, aka Larry Larson, made the necessary disc to replace the spinner. I shortened the length of the tool because my shop is too small for its full length. Here, you can see the full length tool without the disc. I later installed three length adjustment bolts in the empty hub holes - these control the cowl position so that the prop and spinner will fit (I have not ordered these yet).

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Even with a heavy book and a water jug resting on the top cowl, it would not lay fair to the fuselage.

iuoEEhM.jpg


I copied Jack Nystrom’s work here on his RV-3, Hack Job, and made several slits in the inner skin. The slits are 10” long. This worked but I’ll need to fill and seal the slits later.

bh7Elfp.jpg


The top cowl fits reasonably well. The bottom cowl was more difficult, mostly because it needed the top cowl to hold it up. At this point, the lower quarter-turn fastener locations are not in, also the cheeks aren’t trimmed to length. But you can see the disk and the shorter length tool.

eO5OuWY.jpg


In that photo, the wide angle lens (did I mention that I have a small shop?) causes distortion in the fuselage.

Under the small potatoes category is the burning question: do the cowl cheek bulkhead flanges face forward or aft? I have 11 photos showing them. Five said flanges aft, and six said flanges forward, which was my inclination anyway. The plans don’t show it, no surprise, and the SK sketches sort of illustrate that either the person drawing it was lazy or the flanges face forward; it could be interpreted either way. On mine, forward they will point. The actual parts are labeled R and L, and if I followed that, they’d point aft.

Dave
 
You have discovered the magic of David's cowl fitting jig! It made that part of my build the 'knees ...

"In theory, practice and theory are the same. In practice, they are not" Benjamin Brewster 1882

Words to live by!
 
Thanks - I hadn't known the origin of the quote.

Incidentally, here's a look at SK-82, which shows the firewall and cowl. You can see why I commented about either the flange direction or the or the person drawing it.

0cYNNWg.png


Dave
 
Along with the cowl cheek bulkhead flange orientation, there’s another burning question. Do the cowl cheek extensions end at the spar bulkhead as shown in SK-86 or do they extend aft a bit?

UxkVfEb.jpg


I went back into my photo collection and found 15 RV-3s with the cheek extensions ending at or close to the spar bulkhead, 11 ending a short distance aft of that, and 21 ending a long distance aft. Now, without a lot of measuring and calculating, “short” and “long,” as I’m using it here, are probably around 3” and around 6” more or less. And I mean in its most approximate sense. I measured my F-364 pieces and they’d extend aft around a foot, if I didn’t trim them. The front matches the bulkhead curve nicely but the aft end is relatively poorly formed. If I did any trimming, I’d need to rebend the entire part. And if I used them at their current length, I’d need to reform the aft end. You may remember the fun I had bending the bottom aft fuselage skin. Well, these are thinner, a plus, but a much tighter bend, too, which makes it more difficult.

Alternatives are using the RV-4 part, a fiberglass section, which needs to be extended in the front, as a few RV-3s have done or making my own from scratch of fiberglass, as John Nystrom did on his excellent plane. I thought about it and ordered the RV-4 parts from Van’s. These are subject to their wait and ship mode right now and should be in this coming week, but I won’t need to put them on just yet.

I’m supporting the lower cowl with bungees in the back, attached to the cowl by clecoed tabs, and the cowling tool and clamps up front. Here’s the back.

SQeJFF3.jpg


The forward lower cowling has spacers in the cowl tool for spacing.

8vQpXG1.jpg


Dave
 
The cowl cheek extensions arrived and as expected, they don’t fit my RV-3B. Remember, they are RV-4 parts, so there’s no reason that they should. They are a bit short on width, skin to outboard face, as shown here.

C4kt3G9.jpg


But the overall curve is decent. The best fit seems to be with the flanges trimmed off and the extension’s edges extended a bit and new flanges formed. One idea was to use piano hinges for the flanges.

FR5ObbE.jpg


They’d need twisting but otherwise would work. I’ll need them around the front of the right one in any case for battery access. There’s another facet to that, since that extension’s front flange will interfere with the battery… so more change. But they’d probably want riveting to the fuselage skins along their length if I used them as the sole flanges. With fiberglass, glue and a few keeper rivets should suffice. The piano hinges are anodized and I’m reluctant to bond to that surface, merely for lack of test data to guide me.

The side quarter-turn fasteners needed flanges. I know that a number of builders rivet aluminum strips along the sides for that. I followed DanH’s example and made fiberglass strips for that. Trimming these proved one of the dustier, messier jobs I’d had yet: the strips were at exactly the wrong working height and I didn’t come up with anything better. Still, it's done.

j1qS4cA.jpg


Here are the sides clecoed together where the quarter turn fasteners will be.

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And here is the cowl from the front, without the cowl disk but still with the cowl tool on the prop hub. Some work still needed.

s7U9zdq.jpg


Next up is the other airplane’s annual inspection.

Dave
 
With the certified plane’s annual inspection itself done, I can do a bit of work while waiting for some things to arrive to finish that job.

One thing I did was to caulk the firewall overlay around the cut-outs and edges with the FireBarrier 2000+. I forgot to do that before we hung the engine and it was a bit more difficult now. With the help of a 20 ml hobby syringe, though, it went reasonably smoothly, given my abysmal skill at caulking. My talents, if any, aren’t there.

Finally, I installed the ARP carburetor ice detector in the carburetor and the carburetor on the engine. The carb ice detector is that sensor with the wires in front. It has a probe that goes into the throat and physically senses ice, turning on a light in the cockpit. The device is analog and also turns the light on when the voltage drops, so it doubles as a low-voltage indicator. Yes, it takes a slight bit of interpretation to assess, but in practice that’s been fairly obvious. After all, the first action is to pull on carb heat when the light comes on.

My other plane has one of these and it’s proved its effectiveness over the years. I regard it as essential with a carburetor installation.

uReSWzD.jpg



I still need to install the throttle fitting and FAB. For that matter, all the engine controls - lots to do!

Had a visitor at the shop recently. Dan Horton stopped it for a look. It was very good to have someone with that level of knowledge and expertise take a look at this project. He gave me some suggestions, showed me areas where baffles are typically poor, and found a decent location for the oil cooler for when I get that far. All in all, it was a very helpful and enjoyable time.

ToRbfTi.jpg


I got to see his RV-8, and the attention to detail was superb. The little things definitely show up and add up. It was clear at a glance that his comments about the large volume engine cooling air inlets are spot on, with zero bugs inside the inlets. The lower landing gear intersection fairing, the tail fairing and the RV-8 wing root fairing were also worth examining. If you ever get a chance to see his plane, be sure to take some time for a close look.

Dave
 
Before I can do any of the engine stuff, I’ve got to get the cowl into shape. You might remember that the cowl cheek extensions were pending. I received the gray fiberglass RV-4 extensions. And since the RV-4 cowl is longer than the RV-3’s is, the RV-4 cowl tapers closer to the fuselage at the aft end. The extensions are therefore not as high. This led to a decision needed, between the three approaches to fixing this.

I could position the extensions aft far enough that the shape would extend between the aft end of the cowl and the front of the extension, more or less a flat wrap. Here’s how that fits:

ztEC7B2.jpg


Not so great, huh?

Or I could move the extension closer to the cowl and cut off the flanges and make pieces to fill in between the fuselage and the extension:

XXnTSLG.jpg


The final option, suggested by Dan Horton when he was here, is to make new molds and make brand new extensions, as John Nystrom did:

UiEsU6i.png


But that strikes me as labor-intensive. I chose to cut off the flanges and make fill pieces. You'll see those below.

9RGJHf7.jpg


Figuring out how to make the battery compartment and its hatch in the righthand extension was interesting. A lot of steps in a certain sequence. Since I was going to have to cut the front of the extension off for the compartment, the aft portion needed a bulkhead. I made a simple form of thin plywood, with packing tape and electrical tape as mold releases - epoxy doesn’t stick to these nor to duct tape.

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Here’s the back side of the bulkhead, formed in place, complete with flox fillet.

LAkOyXG.jpg


This is what the front looks like after I pulled off the plywood form. There’s no fillet yet on this side, that’s in a bit.

K3Uwj5m.jpg


Before splitting the extension for the hatch, I made an alignment tool so I could regenerate its original joined position.

lnUuLyD.jpg


Before cutting,

e7Z9GfC.jpg


It was removed for the cut, of course.

After splitting, I sanded both front and aft parts and taped the forward section so it doesn’t get bonded to the flange.

QjVLSi0.jpg


There are two pieces of electrical tape to get both a wrap around the end and also to delineate the needed extent of the flange, which will simultaneously help hold that bulkhead and support the hatch cover.

Dave
 
Added the glass to the front of this bulkhead.

okFZxhz.jpg


And then separated the hatch from the fairing and trimmed the bulkhead.

By3PgkL.jpg


Put it together again and back on the fuselage for a fit check. So far it’s fine.

rn0jwOm.jpg


The front of the fairing is about where the cowl cheek bulkhead goes. I’ll need to tweak the aluminum bulkhead, which was just a bit oversize on the right had side, and remove the hatch’s fiberglass one.

Before then, though, I laid up the beginnings of the flanges for the aft portion of this cheek extension. At this point, I’m only using two layers of bid and a cover of peel ply, because I wasn’t sure how well this would work out. So far it seems okay. I expect to add more when this has cured.

PNJtjAP.jpg


Although I have no photo of it, the aft end has been finished off and after adding a third layer of fiberglass, I trimmed the flanges. I’ve added the flanges on the right hand fairing, too.

Have a great Fourth!

Dave
 
Added the glass to the front of this bulkhead.

okFZxhz.jpg


And then separated the hatch from the fairing and trimmed the bulkhead.

By3PgkL.jpg


Put it together again and back on the fuselage for a fit check. So far it’s fine.

rn0jwOm.jpghttp:


The front of the fairing is about where the cowl cheek bulkhead goes. I’ll need to tweak the aluminum bulkhead, which was just a bit oversize on the right hand side, and remove the hatch’s fiberglass one.

Before then, though, I laid up the beginnings of the flanges for the aft portion of this cheek extension. At this point, I’m only using two layers of bid and a cover of peel ply, because I wasn’t sure how well this would work out. So far it seems okay. I expect to add more when this has cured.

PNJtjAP.jpg


Although I have no photo of it, the aft end has been finished off and the flanges trimmed. I’ve added the flanges on the right hand fairing, too, including the area at the aft end. Not shown, they are trimmed. I needed to use a small bit of foam to help shape the aft end, unlike the right-hand side.

nwinXBk.jpg


After measuring and trial-fitting the battery in the right hand fairing, I moved that cowl bulkhead forward a couple inches. The aft end of the battery didn’t fit comfortably inside the hatch - had to make a flange extension piece to do this. Fortunately there’s room - so far - in the cheek area behind the engine.

Here’s the bottom battery mount. The flange extension is on the right side of the battery inside the cowl cheek itself. The brass nut stack is the pass-through for the ground forest of tabs, which is just inside. The ground forest has two bolts. The other one is into a nutplate riveted inside the cheek extension out of sight.

c7XhneQ.jpg


The red pads are some silicone baffle flange material that I had on hand. I used Pliobond to glue them on, this is a somewhat industrial contact cement that’s been available for probably upwards of 50 years. The two horizontal strips nicely account for the mild curve of the fuselage side.

*** Later - Don't use Pliobond for red silicone! The peel strength is approximately zero. ***

With the bottom mount on, I could not resist seeing what the whole battery mount assembly looks like. The orange dots are the magnets I’m using to hold it all together. These are very convenient and I strongly recommend having a couple dozen of them. You can get them here.

There will be a few changes and some obvious trimming. For one thing, the stack of magnets to the immediate left of the battery is just an aft stop. The battery is an empty dummy. EarthX sells these and it’s been very useful for mocking-up the assembly.

jjPmUOE.jpg


Dave
 
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The battery mount is in and the photo shows it latched.

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Dan Christian, whom we we know as Dan 57, flew in for a brief visit. He was traveling from Switzerland to Oshkosh and back in his RV-6. This was not a direct flight, with stops all around the U.S. and Canada. Quite an interesting visit, and a very nice RV-6.

Bk40WFZ.jpg


The fore-aft battery stops were not yet in. I had added a short extension forward for the cowl cheek bulkhead, and after some time jiggling this and that, got the right-hand cowl cheek bulkhead installed. Here it is with the battery mount open. That stack of magnets between the silicone strips and the ground forest pass-though is merely acting as a temporary stop.

spdinYO.jpg


The silicone pieces can be attached reasonably securely with Ultra Blue silicone gasket sealant.

I removed the forward molded-in bulkhead from that RV-4 cowl cheek extension as it was in the way of the battery. Not to worry, there’s plenty of fiberglass work ahead.

Speaking of that, I trimmed off the cowl core from the bottom right-hand cheek area of the cowl for an inch or so, to provide space for the parts that the quarter-turn fasteners on this side attach to. Later I decided to use nutplates for the cowl cheeks.

A small setback…. The hatch did not clear the battery latch. I removed all the stainless latch assembly and replaced it with aluminum and a screw. Everything fits fine now.

flh8ftU.jpg


I’ve started prepping for the hatch hinges - the upper hinge pin can be removed to open the hatch, but the bottom one stays in place. You can see the upper one in the photo. The bottom one, also shown, needs further adjustment.

Dave
 
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It’s been a while since I’ve posted, sorry. I’ve worked on a small variety of things on the cowl and its cheek extensions, making minor progress. Here’s a rough summary.

I figured out an imperfect but satisfactory approach to safetying the hinge pin that’s the battery access hatch lock. It had baffled me for too long. I’d hoped to be able to use safety wire but it appears as if using McDaniel’s safety cable will be a lot easier. Hint, if you’re planning on buying this plane when I sell it, get one of those things; you’ll eventually need it. The red ellipse and arrow identifies the cable and the restrained latch.

FH7RZFW.jpg


I installed the inlet ramps in the upper cowl. As is standard for RV-3B parts, they fit poorly. I used foam to block most of the gaps, and a bit of trimming got me this far. The left hand one fit better than the right hand one. Here it is while still fitting and thinking about it.

jXZoGoy.jpghttp:


For some reason, I had more trouble with the right hand one. No idea why. Here it is at the same stage.

ciQmA4V.jpg


Once I finally decided to press ahead with these, and tweaked and fussed until the lower cowl’s flanges joined okay, I glued the inlet ramps in and after some foam fitting and grinding, used micro to smooth out the joints. After that, a bit of 3 oz. glass over the foam and here we are, with all the ends and edges smoothed and sealed.

fE8PBx6.jpg


I can't say that I particularly like the slopes of the ramps. The right one is steeper than the left, but I suspect that both are too abrupt and steep to be optimum.

Dave
 
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It was time to ensure that the cowl cheek extensions were fair to the cowl cheeks. My shop is a small two-car garage and I needed to be able to step back to get a better perspective on this, so I pushed it out. It hadn’t been outside since before the engine went on and I added some other things since, too. It was heavy enough and the driveway sloped enough that it was a handful keeping it under control. I should have asked for help from a neighbor, but I didn’t. I got the tailwheel up against a handy stump and was glad that I hadn’t had that stump removed - it’s the only stump I let remain so there was an element of luck here.

J6NTksw.jpg


On the right side, I didn’t have the stand-off distance I’d have liked, but it was adequate.

cD0Abib.jpg


Now I’m filling and smoothing the cheek extension fairings where I had to extend the distance they stood off the fuselage, the RV-3B cowl being different than the RV-4 cowl these fairings were made for. It’s the business of adding micro, sanding, adding a touch more, etc. No up to date photos but that’s what’s going on.

One thing I’ve noticed is that in past years, my shop would never get warmer than 80 F. This year that’s not the case. I knocked off today at 84 F. Still, that’s better than outside, where it was well above 90 F. One reason for the higher shop temperatures is that there had been an ash tree shading the windows. It would leaf out in the Spring and the leaves would go away in the Fall, a perfect seasonal sunshade. Like nearly every ash tree in Boulder, it got the ash beetles and died. Had to remove it. Yeah, that was one of the stumps removed.

With the beginning of the school year, I started mentoring an RV-12 project at Boulder High School. I had earlier met with the teacher associated with it and agreed to do that, but later bowed out. Then he got killed on the way to Oshkosh, would have been his first visit there. Turns out the remaining staff have no idea of any of the organization of the project and know very little about it. And I was the only mentor they knew of. As a result, I’m spending some time there trying to get other mentors (volunteers welcome, PM me), finding funding (donors welcome, PM me), arranging for work space (like pulling trees through a keyhole), and somehow getting some organization done. So far it’s taking me more than the 2 days a week I signed up for. I must admit that I enjoy this. There has been and will be somewhat of an impact on this RV-3B project, at least for now. I do plan to bow out if and when they are going smoothly.

Still, I’ve made some slight progress. My list of things that need to be done before I can bond on the left cheek fairing is growing but I’ve figured out how to do some of the secondary details which had mystified me, and I’ve made some progress finishing the fairings.

Dave
 
With the beginning of the school year, I started mentoring an RV-12 project at Boulder High School. I had earlier met with the teacher associated with it and agreed to do that, but later bowed out. Then he got killed on the way to Oshkosh, would have been his first visit there. Turns out the remaining staff have no idea of any of the organization of the project and know very little about it. And I was the only mentor they knew of. As a result, I’m spending some time there trying to get other mentors (volunteers welcome, PM me), finding funding (donors welcome, PM me), arranging for work space (like pulling trees through a keyhole), and somehow getting some organization done. So far it’s taking me more than the 2 days a week I signed up for. I must admit that I enjoy this. There has been and will be somewhat of an impact on this RV-3B project, at least for now. I do plan to bow out if and when they are going smoothly.

Dave,

So sorry to hear about the loss of the programs teacher. Thank you for taking the time to mentor those kids. It’s so important that we give where we can and the impact will be more than you’ll ever know.

Thank you also for your excellent posts. As one with a disassembled -3 dust collector, reading about your progress pushes me ever closer to banging away again soon.

Best regards,

Mark
 
Been tweaking the cowling. On the left side, the top cowl didn’t fair well to the cheek extension, so I cut a slot at the point where the cheek grows out of the cowl, as shown in the photo. Disregard the duct tape, it’s gone.

oCV3ros.jpg


I removed the radius there, and used packing tape on the inside to have something to lay the glass up to. Epoxy doesn’t stick to packing tape. I don’t have a good photo of it, but at this time, I’ve got the first layers laid down on the outside. To minimize filling, I plan to add more layers on the inside after I remove it.

The lower cowl needed extending at the aft end. I seem to have over-trimmed it. I clecoed on some strips of .016 aluminum that I’d taped, and used some magnets to hold them in place. After tapering the inside aft edge of the cowl, I laid the glass over this.

XQHmvpq.jpg


It worked out well but I need to reinstall it to trim the new material.

ouTMvg1.jpg


The RV-12iS mentoring proceeds. Thanks, Mark, for your encouragement. It takes more time than I thought. We don’t have enough active mentors or tools to work with, but we have started the students on the practice kits which were so generously donated. Students don’t get to touch the plane itself until they’ve successfully completed a practice kit, one per student. Some students were getting close and one in particular is doing excellent craftsmanship.

Class meets four afternoons a week but we generally have only one or two mentors per class, but only three classes a week. There are also additional students in a morning class and we don’t have any mentors for them, nor practice kits. I’m reluctant to let them at the plane and since I’m not there then, so it will be interesting to learn how this plays out. Basically, I think that we have twice as many students as we can handle in the afternoon session, and a whole class more in the morning session, all more than the resources can presently absorb.

Dave
 
I installed both the upper and lower cowl and the cockpit coaming. That’s the top that goes over the front of the cockpit. I did this so that I could check that all the lines are flowing about right and it looks like they are. You can see that the left cheek, top and bottom in the back area, needed to be adjusted. Turns out that the gray fiberglass RV-4 cheek fairings are mirrors of each other, but the cowl cheeks themselves are not. The left one was fatter, top to bottom in the back area, than the right.

WjPttFS.jpg


The hidden cowl latch I planned won’t work. The geometry is wrong for that. But I’m working on an alternate similar idea for that and it’s showing promise.

In this next photo, the pad for the new hidden oil door latch is being formed of flox with a layer of BID. The aluminum bar is merely a tooling piece of scrap to ensure that the pads are coplanar.

oj5kY3u.jpg


Since the weather has gotten colder, I brought it in to enjoy the warmth of the house overnight. There’s another VAF thread about a Zizzo folding bike. Since I was looking for a folding bike, I decided to buy a Zizzo Urbano. Turns out the box it came in is a dandy cowl support tool.

jedTeHW.jpg


The Zizzo Urbano is a bit longer, folded, than specified, and most likely won’t fit this airplane. It will fit my Cessna 180, but then a regular road bike will too. Once I had three people and three bikes on board but that took some arranging.

Here’s an update on the high school’s RV-12iS project.

We now have ample funding for the tools and, I expect, some more of the kits. That’s the big news. I will make sure that we keep some money available for unexpected contingencies, because there will certainly be some.

The first batch of students has finished their practice kits. Some of the students have done quite good jobs. We are making sure that all the students are building airworthy kits, although these practice kits will not fly. Some of the practice kits seem to suffer from the learning curve and while they don’t meet that standard, the students have learned from that. The students who finished their kits first and got a passing grade are working on the first airplane parts - yes, we’ve started, on the vertical stabilizer.

I started a VAF blog for that project, here. It’ll probably have fewer photos than this one.

Dave
 
After much finagling, I finally got the oil door’s latch installed to the oil door and its area of the cowl. First, I had to build up a suitable pad to attach the latch hinge to, since none of the surfaces were remotely in plane with each other. That included trying to find a suitable spot. The build-up area is just flox but the bond to the hinge is G/flex. Since the hinge is anodized, it needed to be well-abraded.

The hinge was a one-piece thing glued straight across the oil door and its frame. Keeping it one piece ensured that the holes would line up. I used magnets to hold the door closed and to hold the hinge piece in place while the glue dried. The perimeter magnets are still in place here, and the cut lines are marked.

U0b7o0e.jpg


A Dremel with a cut-off disc quickly made the cuts, and a file cleaned up the edges.

FV7hCd9.jpg


Then came the moment I was awaiting…. And the wire went in smoothly. Pulls out easily, too. And bonus, it does indeed hold the door closed with some pressure on it. Here the wire’s shown in with the magnets moved so they weren’t holding the door closed.

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The hinge part to the right is the lead-in guide and the wire will always rest there. The hinge part to the left is the termination stop and the wire won’t go past that.

Some clean-up work remains, obviously, and the guides and associated parts to the right of the oil door assembly still need to be figured out and installed. The holes in the latch hinge do not point towards the cowl opening so I’ll need to guide the wire outboard a bit for that. Incidentally, for these photos, up is outboard, down is inboard, left is aft and right is forward. The cowl makes that abrupt bend because that’s where the cheek starts.

Tomorrow's Thanksgiving 2022, and I want to wish all of you a wonderful holiday. We have a lot to be thankful for. Among other things, we live in a prosperous, free country and have the freedom to fly. There have been few other generations that could do this. We're at peace and I especially want to thank the people, past and present, who defended our freedoms, our independence and indeed, our constitution. I salute you all.

Respectfully,
Dave
 
Got further along with the hidden oil door latch by making a finger loop at the end of the wire pull and a small flox stop to prevent the wire from going in too far. In the photo, it’s difficult to see the stop at the left end of the piano hinge but you can see the finger loop in the wire and the guide bracket, clecoed in place.

Turns out that in this position, the wire rubs on part of the engine. I’m in the middle of relocating the guide bracket to prevent that - it will move more to the right.

The forward end at the loop (to the right in the photo) is currently unrestrained. I have an idea how to hold it in position, prevent chafing and how to make a forward stop to the wire so it can't be accidentally removed.

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Since I’ve been working on various small things on the cowl, it’s a good time to do any adjusting to the cowl’s aft bottom edge for the exhaust. Here’s the bottom aft edge with no exhaust in place.

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And with the exhaust temporarily in place, we can see that the cowl rubs on it; it will clearly require some change in contour. Less obvious is that the aft bottom edge of the cowl is not a smooth curve or even straight.

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For you engine folks, the exhaust is one of Larry Vetterman’s last RV-3 exhausts before he retired. Here it is from both sides and the center. It’s four individual pipes, no mufflers, no cross-over. The tip turndowns are not on yet. Remember, this is merely a trial fit.

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I looked in my collection of RV-3 photos to see how other builders shaped the cowl contour in this area. There is a wide variety of shapes here. It’s definitely worth while accumulating photos of other RV-3s!

Dave
 
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