Nov 17, 2021     Airfasco Bolt Order arrived Category: Empennage

Haven't had any time to work on the project over the last two weeks, but I did have a few orders arrive.

Shipment of four AN5 bolts from Airfasco. Long enough to bolt the stab to the fuselage. Aircraft Spruce couldn't supply ones long enough.

  Oct 16, 2021     Rudder horns, stabilizer blocks, and more - (5.5 hours)       Category: Empennage

Spent some time clearing the holes at the bottom of the rudder to mount the tailwheel connector chains. Ray rebuilt the rudder many years ago and did a beautiful job on this area. Unfortunately it seemed that some epoxy or varnish got into the threads of the nut plates for the tailwheel control horn. Had to use a tap to clear the threads to bolt the control horn on. Like everything else, it took longer than one would expect.

Had only two of the original stabilizer phenolic mounting blocks. Had to manufacture two more out of a block of phenolic that was 1-1/4" thick. Started by cutting the block down into a single smaller block. Cutting phenolic is very slow and it dulls tools quickly. Even with a band saw, the 15 cm of cutting took about 20-30 minutes. The rate of cutting slowed down as the blade dulled...
Since these blocks need to fit on the upper longerons like a saddle, it was simplest to drill the length of the block and then cut it into the two pieces. Drilling the block was done in stages, starting with a 1/8" drill bit, then working my way up to a 1/4" bit. Once the 1/4" hole was created, I used a step bit to get to a larger hole. My first step bit goes to 3/4". I needed to get to 7/8". My larger step bit goes to 1". Since I didn't need to go that large and I needed the bit to plunge the full depth, I used the grinder to remove the 1" step. This left me with a bit with a 7/8" max diameter. The process worked and I eventually had a block with a 7/8" bore down the length of it. Cutting it in two didn't take too long since most of the cross section was removed by the hole. From there, the mounting hole was drilled and some work was done to finish the shaping and get the proper thickness and taper to match the existing blocks. It took a while with the dremel and the belt sander but I was pleased with the results.

With the blocks in place on the upper longerons, I reinstalled the stabilizer and checked it for level. It was. I then measured the length of the AN5 bolts required to secure the stabilizer to the fuselage. The forward ones require a 6-3/8" grip and the rearward ones require a 6-3/4" grip. I'm going to have to order them from a dedicated aircraft bolt supply company just like I had to do on the wing spars. I'm sure they'll be pricy bolts.

Installed some interior pieces that I recently re-discovered. As parts and pieces are being used up, other parts are being found and identified.

  Oct 12, 2021     Further fitment of empennage - (2 hours)       Category: Empennage

Spent more time getting the empennage to fit better and line up. Discovered that the leading edge of the rudder needs some filler pieces to have a straight and consistent gap along the hinge line.

Also discovered a piece of original fairing to close the gap between the stabilizer and the fuselage. At least, I expect that is what this piece is. There's only one but it fit the LH side perfectly. I also found what looks to be the fairing between the fin and the stabilizer. No pics of that.

Doing some further research tonight, I discovered a photo that I'd seen before but long forgotten. This was taken by Ray when he first received the project. I'm grateful he was so diligent with his photos. The picture shows some of the blockage used to support the stabilizer. See attached. I'll have to dig into the collection of parts and pull these blocks to test fit everything. Again.

  Oct 11, 2021     Mounted empennage and connected controls - (3 hours)       Category: Empennage

Quite a bit of time spent today and not a lot to show for it. Since I'm ordering a new set of replacement rudder cables, I figured mounting the empennage and confirming the length of rudder cables would be prudent. They are correct. While I was at it, I couldn't resist connecting the elevator pushrod to the elevator. This required assembling a few of the pieces that hadn't been assembled before. While there's not a lot to show for it, it provided a good opportunity to confirm some things, and learn many things.
The stabilizer was originally bolted to the rear fuselage with four 8 mm bolts. The original bolts didn't make it in the years of storage and transfer of the project. They are long gone. Fortunately 8 mm is almost exactly 5/16". So some AN5 bolts will be used instead. Resting the stabilizer right on the fuselage longerons allows the bolt holes to line up beautifully. Unfortunately having the stab on the longerons prevents the elevator from moving full travel, so some shims need to be mounted between the longeron and the underside of the stab. There are no drawings for this detail and looking closely at old pictures of the plane, I can't see anything that clearly illustrates this. The one thing that is obvious from some of the old pictures is a large gap between the top of the stabilizer and the lower edge of the fin. A simple fairing would have closed the gap up nicely. I guess that wasn't a concern by the time the plane was finally built. See attached vintage pictures. Regardless, this means I have a lot of room to raise the stabilizer. I shimmed the stabilizer with what started as two of layers of 1/2" thick foam. After experimenting, I think I'll only shim it up 1/2" total. I'll build some shims out of aluminum blocks and some aluminum plate as saddles.

Another thing that took a lot of time was getting the proper travel on the elevator. I found in some old notes that the elevator travel was 30 degrees down from neutral and 20 degrees up from neutral. The fact that the down travel was 1.5 times greater than the up travel is odd. I played with the length of the pushrods and got the travel to be close to 25 degrees in either direction. Intuitively that just seems better. I got my younger son to sit in the cockpit and move the control stick back and forth while I measured travel.

  Apr 08, 2020     Fittings and misc prep - (1 hour)       Category: Empennage

While I was disassembling the plane it gave me the opportunity to work on and clean up some of the empennage hardware and fittings. I've attached a photo of the hinge brackets for the elevator. The pieces for the rudder are identical. As before, beautiful workmanship on the machining and fabrication of these pieces. Aircraft kit manufacturers and amateur built aircraft builders have it much easier today with readily available pieces and parts that can be used. But then, they don't get the custom manufactured pieces like these...

  Jan 28, 2020     Trim servo work and rudder mounted strobe/antenna. - (1 hour)       Category: Empennage

Having looked at the great collection of photos that Ray took when he received and disassembled the plane, I realized that I had the trim servo arm in the wrong position. It can travel a full 360 degrees and I had the arm positioned 180 degrees from where it was supposed to be. I connected the servo motor up to some power and rotated it the required 180 degrees. While I was at it, it was a good opportunity to experiment with the trim indicator gauge. Experimenting a bit I figured out how it was supposed to be connected.

The trim position indicator in the cockpit is in French. The instrument has the title TAB and it has a needle that swings between two extremes. The one extreme is titled CABRE and the other extreme is titled PIQUE. My thoughts are CABRE refers to CLIMB and PIQUE refers to DIVE.

My reasoning is that CABRE translates literally to REAR. If I put that in the context of a horse, a horse that rears is on it's hind legs and it's front end is certainly higher. PIQUE translates into PIKE, which also implies stab, as into the ground. So my reasoning is that's the trim set for nose down or diving attitude.

See attached photos. As you can see the trim indicator moves in relation to the trim tab.

One of the improvements I'm making on the plane is to provide capability to add strobe and position lights and the potential for ADS-B out. This requires a special antenna for ADS-B. I really like the antennas that uAvionix has developed that are direct replacement for the standard lights. This requires a mounting area on the rudder. I spent a bit of time trying to determine the ideal location both for antenna operation and structural integrity of the rudder. One of the risks is that it locates the antenna about shin level. Anyone walking around the tail of the plane risks running into the antenna.

  Jan 25, 2020     Elevator trim motor - (2 hours)       Category: Empennage

Decided to change it up today. Wanted to work on something different for a bit. The elevator trim motor has always intrigued me. Like many of the pieces on this plane it's a one-off. It's machined from a solid block of aluminum and it has some electrical connections on one side of it and an arm with a ball on another side. There are 6 electrical connections. Two are obvious connections for the resistive potentiometer to identify travel. I'm not sure what they fed on the instrument panel as I've not noticed an indicator to show trim position. The other 4 connections had me intrigued. I removed the electrical plate to see how things are connected. It's a combination of 2 limit switches that are triggered by a cam on the output shaft and connections to the motor. I also removed the backside of this trim motor assembly. Again, the workmanship of the machining is amazing. The backplate is held in place by two countersunk screws. These screws are removed and then screwed into threaded holes just below their original holes. This pushes the backplate out. The pieces are built so snugly there would be no way to remove the backplate without threading these screws into the holes. Removing the backplate exposes another treasure. There are a series of gears inside that are like watch pieces. They are beautifully machined. They spun ever so smoothly and didn't need any cleaning or lubrication. I'm pleased to say that the motor itself still works. I was just able to see that it was made in Germany and not in France.

Messing around with this allowed me to understand the wiring for this trim motor and allowed me to test it. I then mounted it into the elevator and set the trim arm in the approximate spot where it will be in use. I measured the resistance on the potentiometer over the expected travel. The resistance over that range runs from about 360 to 580 ohms.

Ray had cut out a new access cover plate. I installed it, back drilled it, countersunk the topside and screwed it in place.

  Nov 21, 2019     Finish up of inspection panels and doublers - (.5 hour) Category: Empennage

  Nov 20, 2019     Access Panels and Doublers - (1.5 hours)       Category: Empennage

Completed access panels and finished gluing in doublers. Installed nut plates and counter sunk access panels for tinnerman washers.

  Nov 19, 2019     More of the same - (1 hour) Category: Empennage

As the title says, more of the same. Worked on access panels. Created new, smaller diameter doublers for the smaller holes and glued the doublers into place. Could've used some more cleco clamps to do it but made do with what I had. No pics today.

  Nov 18, 2019     Inspection Panels again - (3.5 hours)       Category: Empennage

Having slept on it, I decided that the inspection panels for the fin and rudder don't really need to be opened up again after the build inspection. So I removed some of the nut plates and once the structure is inspected by the MD-RA inspector, I'll be able to close them up, smooth the panel over and cover the entire section with fabric. I may keep the inspection plates for the stabilizer spar removable. After all, they will be on the underside of the stab and won't be as visible. Additionally, the loads on the stabilizer spar could be greater than the loads on the fin. Being able to inspect there may be useful. But then again, there's no inspection panel on that area on RV's and such. Sure, one can look into the RV stab through the root rib of the stab but you're looking through a hole that's only about an inch and a half in diameter and there's a fin in the way.

I used one of the cover plates for the lower section of the fin and realized that for an inspection plate, it's rather large. It would be suitable if one needed to fit their hands in there but it doesn't need to be that large for the inspector to view the structure. I made a second, smaller inspection hole for the section of the fin above the rib. It didn't feel right cutting into the nice smooth skin but it's what has to be done.

When I opened up the fin, I discovered that Ray, the previous owner, had signed it when he had done his work on the rebuild. Nice little memento there.

I cut 5 inspection holes on the underside of the stab and prepped them. I've also marked out an additional 4 locations if required by the inspector. Check out the fancy machined nut plate assembly. Beautiful machine work. There are some other nut plate assemblies elsewhere in the plane and they are simply nuts tack welded onto a steel plate. I think the airplane went through different levels of attention during the build. I'm guessing that early in the build there was a lot of this fancy machining. Later in the build, I think they were anxious to get it done and components weren't made as complex and expensive. They were still perfectly acceptable for its purpose, but not nearly as much time and effort to make each piece.

  Nov 17, 2019     Inspection Panels Doublers - (2 hours)       Category: Empennage

Continued with inspection panels for empennage. Wanted to use nut plates and screws from the spoiler access panels. Removed nut plates to discover that the rivets for the original nut plates are something slightly smaller than our today's standard 3/32 AN rivets. 3/32 rivets wouldn't fit in the holes on those nut plates. Looked at the screws holding the cover plates on and found that the closest screw to them is a 5-40 screw. Yes, a #5. An M3 is close but the 5-40 is even closer. So, some soul searching here and the reality is that I'm going to have to make some changes to the aircraft to make it reasonable to rebuild and to maintain. So, after some work cleaning up those original nut plates, I'm using brand new nut plates and 6-32 screws to hold the covers on.

  Nov 14, 2019     Building inspection panels and doublers - (1 hour)       Category: Empennage

Since the empennage was built/rebuilt and closed off by the previous owner, Ray, I need to create some inspection ports. This will allow inspection for my comfort and for the satisfaction of the MD-RA inspector. In reality, I'm not worried as Ray's workmanship is really nice, but as mentioned, the ability to inspect is necessary.

Spoilers were originally installed on this plane. Any articles about the plane's flight characteristics mentioned that the spoilers were made inoperable. It's no surprise as the spoilers were mounted in front of the ailerons and likely impacted the roll control of the airplane. The spoilers were scissor type that opened above and below the wing like you'd see in a high performance sailplane. They are a real thing of beauty in the workmanship to make them. I suspect that when they opened them up though, they really scared themselves. I used to fly RC sailplanes and I was amazed at what an impact the small spoilers had on the glide ratio of the sailplane. The spoilers on the Dalotel covered a much larger portion of the wingspan and would have likely made the plane drop like an anvil, an anvil without any roll control. Pretty scary. By eliminating the spoilers and all the mechanism to run them, I'm shaving something like 20 lbs off the weight of the plane. Gotta love that.

There were a couple of inspection panels on the underside of each wing to allow inspection of the spoiler mechanism. Since I'm not going to install the spoilers in the rebuild, I thought it would be neat to reuse these inspection panels on the empennage. Unfortunately the original inspection plates are thicker than the skin on the empennage so I decided to make some new panels out of leftover mahogany ply from my last project. Inspection panels and the associated doublers are pretty easy first steps in the construction process. Of course, the doublers have to made up in two halves to fit through the inspection hole.