16-Controls-Autop.
Chapter 16 Control System
Autopilot servomotor install for a Dynon system A material list is at the end. I ordered from Aircraft Spruce and CG Parts. The work shown here will be a compromise approach. Since I will try to use some of the work for the first type servomotors. The rotation axis is different and so everything will work at a 90 degree vector to the original install. The difficult install is for the aileron (roll) servomotor, so I did that first. If you have already placed your centerspar, then you can still do this install, but your back is going to get sore in the back seats. I know that the servomotor will fail one day and so I have planned for the removal and reinstall to be made from the back seat area. The way the servomotor works lends it install to it at a 90 degree angle to the aileron control rod at the firewall (aka CS-125). You can do this aft of the firewall on the "hot" side (see last pic) or forward of the firewall and install below the centerspar. To do the forward of the FW install, you need to transition the rotation to the aft of the FW and there is the reason for the "ugly", but very strong transition piece shown in the first three photos.
(doubleclick any image for large view)
Please note!
(As of December 14th of 2009)
Everything in this section is being reworked and rewritten, due to the demise of BMA. I am removing the BMA servomotors and switching to Dynon servomotors. Go to chapter 23 for an instrument list for IFR.
In the first photo, you see parts made from scraps of the LG bulkhead. My large scrap was not symmetrical in shape at the end, but I made do. From the parts list, get the CS-124 and cut off two inches off the end (excess length anyway) and set it aside with the LG bulkhead "pieces".
I sat the servomotor on the workbench on its end so that you see it like in the second picture. I taped the servomotor to keep dripping flox away from it. I even taped over the "arm" and then punched through where the two bolts go. Here is the most important point. When you flox the pieces together with the two inch piece of CS-124 tubing, you rotate the arm of the servomotor and true up the alignment of the CS-124 tubing. If the tubing is not lined up, then you will wear out your servomotor with the binding action, your controls will not handle smoothly. You have plenty of time to check this and adjust during cure. Obviously, curing is done in the position that you see in the second pic.
Look at the first picture. This is the CS-124 tubing connected to CS-125. I used the plans Boston bearing, because you need short length. There is precious little room from the FW to the heat duct area. You have to center the install to not intefere with rear passenger seating. You may have to change the hear ducting to allow for the servomotor install.
To start: mark the centerline on the FW and transfer that line onto the LG bulkhead. If you have already installed the CS, then you will need to look at all of the pictures and then modify this install. I took some pictures today (10/31/2009) to see how someone might do the install later. Please note that the top of the LG enclosure is not perpendicular to the FW. The final install of the servomotor shows more flox aft to make up for that. The hole in the FW is a 7/8th inch size at the centerline of the FW and 3&3/4th inches down from the center of CS-125. Expand the hole with a dremel to allow a loose fit of the Boston fitting and especially expand in the up and down direction to allow some "play" to get the best placement at the floxing time. You will have to allow for the addition of the MM3 to the CS-124. Drill a center point hole on the CS-124, approximately halfway between the two holes already present. Next, put the CS-125 in the neutral position (centered) and drill a 7/64th pilot hole and then a 3/16th hole for the MM3 from top to bottom. The play in the MM3 is forgiving on the vertical axis and the CS-125 will rotate to align. Attach the MM3 to CS-125 with AN960-10 and MS21042-3. Later, after the engine install, you will score the threads with a hack saw blade and flox the AN-960 to the MM-3 to prevent engine vibration from causing looseness. On the already drilled center hole on the CS-124 assemble the MM-3 to it with AN3-5A, MS-2104-2 and one AN-960-10 washer and one AN970-3 washer. The two washers will go in the position of the CS-201 as seen in view B-B of 16-4 of the plans. I used the AN3-5A because the 7A length was too close to the firewall, due to the mounting on the center axis of CS-125.
Now, if you look at the first picture, you will see some marked lines. In the third picture you see that the CS-124 is cut off and ready for drilling the bolt holes. How long is that CS-124 length. I put the servomotor in place and inserted the excess tubing from aft of the FW through the Boston and into the ugly "transition" piece. I marked point that is directly below the center axis of CS-125. Next I marked where the tubing goes into the transition piece. Look at the third picture, and then figure out where to cut the CS-124 tubing. With the CS off, this is no big deal. I marked the neural position on the CS-124 before I took it to the bench to drill the bolt holes.
Next , the two holes are drilled through the transition fixture and the aft end of CS-124. Set the servomotor on your workbench and let the servomotor arm hang down and screw through the arm in one of the open holes into the side of the table and then screw down the servomotor to the table top. I clamped as in the last picture of the previous set of pictures there was a clamp and the tick lines for alignment. Drill the side to side bolt hole, 7/64th pilot and then 3/16th inch hole for the AN3-14A bolt. Make sure that insertion of the bolt is smooth and lightly secure. Drill the top to bottom hole the same. The next picture is of a 4 ply BID pad for the securing of the servomotor to the LG bulkhead. I used Tee nuts and bent the prongs flat and they were #10-32 X 5/16th with MS24694-S54 bolts. Later, I buttered the bottom of this pad with flox to secure it to the LG bulkhead. You can refer back up to the set of three pics of the final look. Be sure to place some ortho wax on the bottom opening of the Tee nuts to prevent flox inflow. I had to trim this pad to not go over the covers to the LG access holes. You see that I used aft mounting holes. If your CS in already installed, then you will not want to use the butter with flox idea. You do not want to secure the servomotor without having CS-124 on and tested for interference. Remember to insert the Boston bearing from the forward side of the FW. When you have smooth action, then you can add a small and thick portion of flox around the gap of the Boston bearing. Don't push through any, because it's close to the transition piece. I add a little bit of micro to flox, when I want it to stay put. One last trick on the motion of the servomotor. If you have some binding, and you loosen one of the mounting screws and it goes away, then slip a washer underneathth and then screw back through that for a permanent fix.
Pitch servomotor
Make a platform 3&3/4 inches to 4 inches wide and mount it forward of the IP so as to not interfere with any of the IP instruments (6.5 inches for me). I ended up with this platform being 3 inches aft of F-28. At the midpoint of the platform it rises 18.5 inches from the cabin floor. The servomotor is mounted upside down onto a doubler to the platform. So the servomotor screws to the doubler and then the doubler screws to the top of the platform from underneath, and then the linkages are connected to the canard lift tab. I used Tee nuts for the doubler to platform ( #10-32 X 5/16th the bolts are listed later) In chapter 17, you will see that I added the manual pitch control, and it did not have any interference with this platform.
The second pic shows the left list tab (NC-12). I took out the AN4-11 and replaced it with an AN4-20(drilled). The head of the AN4-20 will have to be like this (inboard). This is a modification of view B-B of page 16-4. From left to right the order is: MS-21042-4, AN970-4, CS-201, MM4, CS-201, NC-12 lift tab, AN970-4, CS-201, MM4, CS-201, AN970-4, AN4-20(drilled). I plan to add a safety wire through the AN4-20 after the final install. The picture does not show the addition of the AN970-4 to the right of the lift tab ( I added that for snugness). If that washer interferes with the lift tab weight, then drill out a smaller washer to the AN4 size and substitute.
As per plans for the controls to the lift tab, you use 2024T3 1/2 inch tubing and connect to the servomotor like view B-B of 16-4 and use an AN4-11A at the servo arm. When you cut the tubing, go for a 90 degree angle of servomotor arm to the tubing.
The third picture shows the #10-32 bolts as 1.5 inch on the doubler and 2.0 inch to install the servomotor. As of this rewrite on 11-01-09, I am going to change to 2.0 inch for all and add nuts on the top to safety for after install loosening. As always, the Tee nuts have to have some wax over the holes, prior to glassing. The picture below is right before I finished the install and before I added the manual pitch control. See the last picture in chapter 17 for a later view.
Supply List:
CGProducts (CozyGirrrl.com)
Quantity
4 CS-201
1 MKCS-124L (drill your own center hole)
2 CS-1A insert (drilled for MM4)
Aircraft Spruce
Quantity
1 MM-3 Aurora Bearing (for CS-125, you need smaller there)
2 MM-4 Aurora Bearing
2 AN316-4R Nut, thin check
3 MS21042-3 Nut, Stop
1 MS21042-4 Nut, Stop
1 AN4-5A Bolt undrilled
3 AN970-4 Washer, Flat
1 AN970-3
6 AN960-10
1 AN4-20
3 AN-14A
2 AN-16A
1 AN-11A
3 AN-7A
1 03-32500-2 2024T3 Alum Tube 1/2 X .035, Two feet
2 MS24694-S54 (for the rear pad)
Lowe's
10 #10-32 X 5/16 Tee nuts
2 #8-32 X 1/4th Tee nuts
10 #10-32 Comboround bolts 2.0 inches
Chapter 16
As I put in the controls, I did some chapter 24 work ( armrest and then seats) and some chapter 21 work. I ran the fuel lines from my fuel selector to the strakes area and to the FW. This rewrite is after the strakes are done and the sumps fit around the fuel line exit points.
The phenolic blocks (CS-108 and CS-118) get bad press. The problem lies with alignment of the blocks at a 90 degree to the control tubing. If the control tubing goes smoothly into the phenolic block at the lab bench, but then the controls are stiff after install, then loosen the bolts on first one side of the block and move the phenolic. If the binding is relieved, then add a washer there. If the binding worsens, then it is the opposite side that needs the washer. Track down the binding points and these will work smoothly.
The second picture shows the two pieces of "C" channels that I glued together ( you have to cut off a little to make the rectangular shape). There are three reasons for these. The first is that you get even platform to install the rudder cable conduit and fuel line(at the aft section). They are more flame resistant, and they are easier. The BID sample ignited at about 30 seconds with the propane torch and the grey C channel did not ignite and flame even after 90 seconds. The heat was applied to the opposite side shown in the pic.
The height of the entry of the rudder cable into the electrical conduit at the LG determined the water line for these gray conduits. I used the 5 minute epoxy to tack down the rudder cable conduit, and then placed BID strips around the conduit to secure it. I enlarge the hole where the electrical conduit meet the front seat.
Lay out all the tubing pieces in order on you table. In the later pics, you will see the red dashed line on the top side of the control tubing and you will see left and right marked on each piece. Every time, that you drill a hole it will be lined up from top to bottom evenly. The fuselage is to the left in the first picture on carpeted saw horses screw down onto a sheet of plywood. I did some work with the fuselage like this, but most of the work was done with the fuselage turned on its side (I tied it to secure). I used the side position for the armrest fabrication ("glass down"). Back to the controls. I got out some baggies and a sharpie and bagged all of those little parts for the area where they go. Later as I did the wing install, I was able to pull the relevant baggie back out of the chapter 16 plastic shoe box and install the parts. I keep this setup on the table until, I finished chapter 16. The second and fourth pics show the aileron control function being locked in the neutral position.
The picture in between those is showing the little inset on the workbench for drilling rivet holes. Drill the first and place a finishing nail in the first hole before drilling the second. Rivet the second hole and then remove the finishing nail from the first hole and rivet that one.
The last picture shows the extra birch supports with a BID glass overall. You have to make CS-109 and CS-118 (left and right) and install them first with the control tubing, ect.
In the second picture, why do you need these supports? The strakes with the 300-400 pounds of fuel plus any baggage are supported by the CS aft and the side of the fuselage where these armrest go, so the armrest are a part of the support system. Also when you crawl (fall) into the back seat, then you've go to catch yourself on these armrest. You don't want any width added to the armrest or the Mark IV is a Mark III. I made paper templates for each F.S. point (you know). Since the fuselage curves more than the inner surface of the armrest, each set is different and I labeled each set and left and right. The fuselage is shown on its side raised up on the saw horses.
Now skip over to the last picture. The "F" is where the fuel line will exit (see the later pic). The wood pieces assemble like this. The bottom piece slide on first and then the top piece overlaps that and you tape them together and add the triangle support. Make sure that they don't interfere with the controls and then 5 min epoxy and then add small BID pieces later. The first picture answers how you get access to the AN3 bolt to remove the controls at the FW. Doubleclick the picture to see the small panel, that I cut out later with a small dremel disk. I added three Tee nuts for reapplying the panel. In chapter 18, there is information on the internal drip rail for the canopy.
In the first picture, notice that the small triangular support for CS-109 has a notch cut out. This was needed for the manual roll control action. The Strong's pitch control is shown. It is a great product, but since I have a servomotor for pitch on the autopilot, I wanted and installed the plan's manual pitch control for my initial climb, and then again for the descent to land. I don't want a "over controlled" feeling on the pitch controls. So I have a Strong's pitch control to sell for one third off. I will remove the previous sentence when it sells. My e-mail is on the first page of the site.
The last picture shows the fuel line installed. The "F" mark was about 1/2 inch below the bottom surface of the CS-121 tubing. Take this picture on left and right to guide you when you cut out the access panel for the AN3 bolt removal. I really, really suggest that you run your fuel lines right here at this point. The fuel line from the selector back to the FW taps in on bottom port on the plans control valve. The back port is just plugged. Also notice the ugly pull strings for electrical wiring. There was room for rear pockets in the armrest. I went on at this point to chapter 24 work and did the rest of the armrest and the seats, while I could still easily turn the fuselage on its side. See chapter 24.