Front Landing Gear Doors

Front Landing Gear Doors

The first moving part...

With the bulkheads installed, the next thing is to install the front landing gear doors.
(Actually, this would have been easier if completed BEFORE the bulkheads were installed, but this is the order I did it in.)

The hole for the gear doors was cut out way back before the bulkheads went in, as per the build manual.

The first thing I did was to cut out the gear door assembly part, to fit the opening in the fuselage.

Here the gear door assembly has been trimmed to fit the fuselage opening, but is still one piece, and has been hot glued in place for making the hinges.

Next I cut out the swing arms, which came as a fiberglass panel with the cut-out shapes already drawn on.  Unfortunately, I did not take any pictures of cutting out the swing arms, or bonding them to the gear doors.  However, they can be seen in later pictures of assembling hinges.

Side note, to future builders:  Do not cut out the swing arms as per the templates; because, there are better ways of doing them, that have not been updated in the templates or manual.  First and foremost, cut them out wide, you can always trim them later, especially to the top or back of the swing arms.  Chad instructed me to profile the swing arms a bit "deeper" to allow them to fully open without needing to cut out channels for them, in the gear door flange.  Those channels will allow more airflow and water into the nose, and are not needed.  Instead, the inside of the curved section will get shaved down until they open all the way.  I will point this out later, but for now keep them extra wide to the outside of the curve.

With the swing arms cut out, I bonded them into the gear doors, as per the manual.  I allowed them to go in pretty ugly and blocky; knowing I was going to clean them up later.  Once they were securely bonded, I sanded them down so the bottoms were only slightly higher than the gear door backing.  I also made some epoxy slurry to make a nice smooth surface which gently goes up and over the swing arm bases.

The swing arms bonded into the gear door assembly, with the threaded rod used to make sure the hinges lined up properly.

Next, I started on the tabs.  I originally followed the instructions on how thick to make them, using a combination of BID and TRIAX glass; however, when that dried, I was very unimpressed with the strength of the panel, so I doubled the thickness, by glassing more layers onto the panel.

My fiberglass panel with the gear door tabs drawn on, and ready for cutting out.

 Using a band saw and drill press, I cut them out and drilled them as per the templates.

The tabs  ready to be fit for each location.

 Since the holes were already in the tabs and the swing arms, all adjustments of where the two lined up would be made by cutting the tabs down to the right size.  The build manual did not give any hints as to how to do this, so this is what I came up with:  I used a stir stick to measure the distance from the center of the swing arm hole to the fuselage, where the tab would mount.  This gave me a rough length to cut the tab down to.  Once important note here is that you have to do it for each tab, not just each each swing arm.  Since the fuselage is very curved here, especially at the front, the same measurement is not used for both sides of the swing arm.

Using a sharpie to mark the stir stick at the right distance from the fuselage.

The focus was a bit off, but you can see the little dot made by the sharpie.  I then cut the tab to just a bit longer than this, to allow for custom fitting it into place.

To get the tabs fit perfectly, you will need to use the bolt and 2 washers used to properly space them for installation.  Again, the steep curve of the fuselage here means the thickness of two washers makes a huge difference on the height of the tabs.

The front most tabs really get cut down a lot; however, the exact angle the swing arm is installed at will make this vary quite a bit.  Note how wide the swing arms are here, later they will be sanded down to allow the door to open with them going around the door flange.

 This process was slowly and painstakingly repeated a total of 8 times to create all the required tabs.

Here you can see the four front facing tabs, and how they are all very well contoured to the fuselage wall.  This will facilitate a very strong bond.

The next step was to bong the tabs into place.  I did not do this exactly as described in the manual, but I am confident it is at least as secure as the factory method.  I started off following the instructions by mixing a thick epoxy slurry, affectionately called "peanut butter", due to the color and consistency.  This was then applied around the base of each tab, keeping very sure not to accidentally bond the hardware to the tabs!  At this point, I tried to make it neat, but was not too worried about it.

One of the front tabs initially bonded in place.  

While doing this, I found the space between the tabs way too small to effectively do the bid reinforcement, so I decided to do it differently.  As I had already doubled the thickness of the tabs, they were plenty strong enough, so the only concern was that they were attached to the fuselage strong enough to not ever be broken by the operation of the hydraulics.  Therefore, I decided to put a super thick fillet of peanut butter epoxy on the tabs.  For this part, the tabs were already initially bonded in, so the hardware and door were removed, and I went to town applying the epoxy slurry.   I tried to not get much up into where the washers would go, but was not too worried because I could always sand it back off, if there was too much anywhere. 

The initial bonding was just a small fillet designed to hold it just long enough to remove the hardware and finish bonding them in.

Here you can see how thick the final bonding went.

With the tabs bonded in, I was now able to cut the door assembly in half, creating the two front gear doors.

I then had to trim the swing arms to allow the doors to fully open.  Several sessions of sanding and fitting were required till I got the doors to open all the way, without putting any cut-outs in the door flange.  Eventually they ended up pretty lean at the corners; this is why I recommend cutting them out wide to the outside.  After all, it is much harder to put material back on, then take it off.

When compared to the original size, there swing arms are very slim.  This ends up being a problem later when attaching the door opening mechanism, but that will be covered later.

Looking down through the gear door opening, with the doors on.  It shows that the doors are opening up wider than the actual doorway, yet there is no cut out in the flange.

From the outside, you can see just how far these doors are able to open.  I could have left a bit more material on the swing arms, but I preferred not having to worry about the doors opening wide enough.

With that, the gear doors are complete!  Eventually, the outsides will need some cleaning up, but for now, they are perfectly functional.

The front gear door opening mechanism is not installed until the front retract system, so it will be covered there.

In the mean time I have been working on prepping to install the keel...