Monthly Archives: May 2016

Empennage Tips 1

This entry was posted in Elevators Empennage Horizontal Stab on by

Previously I began work on the fiberglass tips for the horizontal stabilizer and elevators. The tips for the elevators have very close edge distances in order to not interfere with the end ribs. Here you can see the first two reinforcement strips I made to remedy the problem for the left elevator. I expect the same thing to be required for the right side.

Picking up with the right side, I trimmed the horizontal stab’s tip by inserting it and marking the intersection.

Here is the result after the cut. This is a good point to note that I may need to trim these further after   glassing in the elevator tips to ensure I have appropriate clearance and alignment. I bought some foam at home depot to close the back portion of this tip in.

Van’s specifies that you need 1/4 inch of edge distance in the fiberglass for this tip. This can be tricky as there isn’t much room for error. My approach was to mark the 1/4 inch line, and the line at which the fiberglass intersects the horizontal stab. This allows me to measure the line for drilling on the horizontal stab that will provide 1/4 inch of edge distance. There was a little more wiggle room on the left side than there is here on the right. On the left, it was possible to get both the edge distance for the fiberglass and the aluminum. On the right, I will be slightly short of the appropriate edge distance for the aluminum but just fine for the fiberglass. Of the two, I’d rather have the fiberglass OK, and the aluminum a bit short.

Here you can see my approach a little better. 1.5″ between rivets, and I started 0.5″ from the rear.

Came out nicely.

And perfectly within the edge distance guidelines.

Again, the elevator tip needs to be trimmed to 1/2 inch to avoid interference with the end rib. This all but guarantees an edge distance issue.

I made two more backing strips from aluminum and set about drilling and epoxying them to the tips.

Here are a few different pictures. I clamped the strips in place and drilled. After drilling for the rivet holes, I removed the strips and added additional holes. These holes will fill with epoxy and create a stronger bond. I sanded the strips with 100 grit sandpaper to maximize adhesion.

Here is a good demonstration of my thought process. There strip has epoxy underneath and on top. The two are connected by multiple additional holes. In order for these strips to come apart, not only will the aluminum need to separate from the epoxy but the epoxy will need to crack at these points. 

Here is the strip in place for curing overnight.

Fastback 16

This entry was posted in Showplanes Fastback on by

Its time to begin the installation of the forward fuselage upper skin. The first step is to install the reinforcement that will be used to mount the fiberglass panel cover. This requires a double flush rivet.

And here you can see the results. 

After I completed this it was time to prepare the instrument panel. I know there is some custom work that will be required here, so I wanted to set it in the fuselage to examine my options.

I will post a few photos of the Showplanes project’s panel here tomorrow. One of the things he did was to expand the center cover by creating a panel face that covers the entire structure. This allows you to create an extremely clean front, cover up a few of the non-used holes, and expand the removable area of the panel. Below you can see in blue the areas I have marked for removal. I will need to fabricate a new panel from 0.050 or 0.063.

The Showplanes project also has what appears to be a non-prepunched backing to the instrument panel. As mine is pre-punched, I have some additional considerations in the placement of the nut plates that will be used to attached the instrument panel cover.

The instructions state to start at the center line and mark 19 points (9 each side plus the center point) for the nut plates. However, as you can see below this will result in holes drilled over, or next to existing holes. The result will be swiss cheese.

After a little thought, the exact same number of nut plates can be installed using the middle point of every other hole.

However, this still isn’t optimum. There are multiple places that will have edge distance issues. Further, drilling this in concert with the undrilled fiberglass is likely to be problematic. I examined a few options for the placement of the nut plate. I’ve taken the photos with the nut plate on top for clarity.

Option 1 is to simply put the nut plate in the exact center. This makes the distances less than ideal in several places.

The second option is to offset the nut plate at an angle. Still not a perfect solution.

Perhaps the best solution is to use one existing hole for one side of the nut plate. This will require drilling outwards instead of inwards, and will certainly be a challenge.

Regardless of the option used, I decided to add a support strip behind. This is almost certainly overkill, as I don’t see this being a structurally important, or high stress area, but with the weight of the avionics, and only fiberglass at the top instead of aluminum like the stock plane, I’ll feel better with a little reinforcement.

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Soon I will need to trim and fit the fiberglass. Before I can do that, I plan to completely rivet the front deck and panel frame. I also plan to make the panel modification and prime appropriately. In the meantime I will be working on the empennage tips to practice my fiberglass skills before diving into the canopy construction.

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I also began work on the empennage tips but forgot to take any photos. As I worked on the left side this evening, I will take photos of the right side for the next post.

Fastback 15

This entry was posted in Showplanes Fastback on by

Quick session in the shop today to epoxy pinholes. Simple process. Mix some epoxy and squeegee them it into the pin holes using either a hotel card or the rubber squeegee I bought. 

It is important to remove as much excess epoxy as possible.