Archive for the ‘NACA Vents’ Category

Installed Fresh Air Vent Hoses – 1 hr

December 19, 2012 Leave a comment

Wednesday Dec 19, 2012

I was really cold in the garage tonight and I couldn’t bring myself to stay out there that long so I just cleaned up a few minor details. One thing I did was measure and cut two sections of SCAT tubing for the fresh air vents and installed those.



I also modified took a picture of the plug I installed in the firewall where the nose gear bolt protrudes. If you look closely you can see that I put a bulge in the center of the plug to allow more room for the bolt. I did that by drilling a slight hemispherical dimple into a piece of 2×4 wood with a 5/8 inch drill, placing the plug on top of the dimple face down, placing the butt end of my ratchet handle on that (it has a domed shape end) and whacking it with a hammer. That worked nicely.


Pitch Autopilot Servo Install, Part 1 – 1.5 hrs

March 22, 2012 Leave a comment

Thursday Mar 22, 2012

After three days of curing the Proseal was finally firm enough that I could rivet the NACA vent scoops to the fuselage skin. Four rivets per side and they are done!

Then I started preparing the autopilot pitch servo for installation. First thing was assembling the pushrod per the dimension in the Dynon instructions. Then I mounted the pushrod to the elevator bellcrank. It was much easier to do that on the bench because you have to slide an AN960 washer between the two halves of the bellcrank to keep from bowing the plates when you tighten down the nut.

I put the bellcrank back in and mounted the servo motor, then attached the pushrod to the motor crank arm. Everything seems to work fine. I may adjust the pushrod a little longer because it looks like the center of the motor travel is off a little from the center of the linkage range. I will also remove the motor again to install a 9-pin connector because that is easier to do on the bench also.

I also did some more trimming of the empennage fairing and I drilled all the holes into the vertical stabilizer with a #40 drill. All these holes with clecos will be drilled out and countersunk for a #6 screw with a Tinnerman style washer.

The fit on the left side at the leading edge is actually not bad. I think I could live with this.

The right side is not as good however. That lower lip does not fit tight against the leading edge and would create extra drag. I will have to do some more work on that region.

Bonded NACA Vents – 1 hr

March 19, 2012 Leave a comment

Monday Mar 19, 2012

Tonight I bonded the NACA vent scoops to the inside surface of the fuselage using Proseal. I decided not to prime or paint the plastic vents before installing them. It’s not necessary on the outside because they will be painted with the exterior of the aircraft some day and it’s not necessary on the inside because they are so far up under the instrument panel that you would have to really go out of your way to see them when the everything is completed. You can barely see the fillet of Proseal on the lower part of the opening in this photo. I will rivet them after the Proseal has set (a day or two).

Here is one from the inside.

Categories: Fuselage, NACA Vents

Empennage Fairing and NACA Vent – 4 hrs

March 18, 2012 Leave a comment

Sunday Mar 18, 2012

I continued work on the empennage fairing today. Here is a shot of the notch I cut for the elevator bellcrank tube tube. I iterated this notch until I got 1/4 inch clearance on both sides. Cutting fiberglass sure throws up a lot of dust.

I also took a small amount of material off the front where the vertical stabilizer leading edge mates. This was to try to get it to mate more tightly at the leading edges of the horizontal stabilizer.

Underneath the vertical stabilizer is a gap fairing called the F-794. Unfortunately I have to drill out five rivets on each side for this part. I don’t recall any mention of this in the fuselage plans when I riveted the longerons to the side skins. It would have been nice. Anyway, I had to trim about 1/4 inch off the upper edge in some areas of this part to achieve 1/8 inch clearance to the vertical stabilizer bottom skin which is for the rubber seal that you see inserted in this view. I got the left side trimmed and fit but I still need to do the right side.

I started drilling the fairing mounting holes to the empennage at the leading edge and worked aft. The first hole was marked and drilled with the fairing pushed flush against the vertical stabilizer leading edge. The holes in the vertical stabilizer are already drilled so I had to sight through the fiberglass fairing which is semi-transparent enough to spot them.

Then I just continued aft one hole at a time to drill and cleco to the vertical stabilizer holes. I used electrical tape to mark a trim line about 1/2 inch from the holes. The tape allows me to define a nice smooth curve which I’ll use to mark a line for trimming.

Back on the NACA vent installation, I located and marked the position for the right side NACA scoop and prepared the surface of the fuselage skin for Proseal. I also sanded the mating surface of the plastic vent scoops to give them good surfaces for bonding. I did not bond them today because it was really cold in the garage plus I wanted to think about painting these before installing.

Oh, I also made eight little doublers from .025 aluminum sheet for the vent scoops so the rivets don’t compress down into the plastic.

Aligned Rudder and Remade Stops – 8 hrs

March 17, 2012 Leave a comment

Saturday Mar 17, 2012

First order of business this morning was to get the hinge bolts installed on the rudder. When I originally installed the hinge bearings on the rudder I aligned them to the dimensions shown on the rudder drawing. When I installed the rudder two days ago I could only get two hinge bolts in. The third bearing was significantly misaligned. Oddly enough the written instructions in the fuselage section tell you to initially set the hinge bearings to dimensions that are different than the rudder drawing. So I removed the rudder and reset the middle and lower bearings to the dimensions specified in the instructions. When I reinstalled the rudder the two upper bolts went in easily but the lower one was still off but not nearly as much as before. That’s when I remembered that I had not installed the washer between the vertical stabilizer main spar and the aft bulkhead of the fuselage on the left side to account for the .25 inch left twist of the rudder. So I unbolted the vertical stabilizer spar and inserted the one lone washer between the facing surfaces and bolted it back together. To my amazement, the hinge bolt then slipped right into the lower bearing. And the rudder now operates very smoothly.

Next up was installing the rudder stops I pre-made a long time ago and checking the angle range. Well like many other builders I found that the stock dimensions of the stops allows significant over-travel of the rudder. The distance from the rudder to the corner edge of the elevator is supposed to be 1 – 1/8 inch. As you can see in this photo the distance was more like 0.4 inch.

So I set about to remake the rudder stops. After making a few measurements I ended up with a new left stop that is about 0.2 inches longer than the original stock stop. In this photo the new left stop is placed back to back with the right stock stop for comparison.

With the new stop installed the distance is right at the 1 – 1/8 inch mark as desired. It’s a little tricky understanding this photo because the rudder is so reflective.

So made a similar stop for the right side and I drilled them to the fuselage at all four holes. Here you can see the left stop installed. I still need to prime these new stops and rivet them on.

Then I started fitting the empennage fairing. Back to messy fiberglass work. I had to trim the aft end to clear the elevator bellcrank tubes but you can’t really see that in this picture. There is going to be a considerable amount of work to get this part completely installed.

I also worked on the alignment of the trim tab. Last time I drilled holes for the Wd-415 in the wrong place in the E-616PP cover plate. So today I made a new cover plate out of 0.025 stock. It was a piece of cake and only took about 20 – 30 minutes to complete. Then I played with the alignment of the Wd-415 on the trim cable to get the desired +25/-35 degrees of trim flap motion. In this photo you can see it in the full up position although I understand that I will never need anywhere this much deflection in actual use.

Then I moved on to the NACA vent installation. Some people just use Proseal to hold these on. I feel more comfortable with a few rivets to add a mechanical attachment in addition to proseal so I drilled four holes in the flange of each vent. I placed the vent on the fuselage and aligned it by eye at the outside opening then marked the perimeter of the flange on the inside. I put electrical tape around that outline and then removed the primer with a combination of MEK and scotchbrite. Here is what the left one looked like after preparing the surface.

Then I put the left vent back into place and match drilled through the NACA vent flange and the fuselage side skin. I dimpled the skin holes and countersank the flange of the vent. Here is the left side ready to be bonded with Proseal.