I thought it would be a good idea to post the method I use to install gear doors. There have been a lot of posts lately asking for guidance, so I hope this helps.
I don't have an unassembled model to use for this, so I took pictures from a solid model I created. If you use this method your gear doors should come out just about perfect.

Disclaimer: this is how I do it, and it has worked for me. If you don't like it, I don't care, just don't use it. But guess what, this is how it is done on Mach 2 fighters.

I selected a curved surface similar to an F-16, it would work the same on a flat gear door such as an F-15, only that it would be much easier.

Good luck!

This is only a brief description of what the model represents. This is the landing gear door area. Most kits have the wheel well cutout already done, with a lip all around it that helps seal the door when it is retracted.

Step 1. Position the first hinge on the fuselage. You want the base of the hinge that will come in contact with the door as close as possible to the fuselage edge, at the lip/fuselage boundary. Mark the location of the hinge on the fuselage, and mark the fuselage lip area around the base that will be in contact with the gear door.

Step 2. Cut the fuselage lip in the area around the hinge base. (Note: Only trim the lip, do not trim the fuselage skin, otherwise it will look ugly. The boundary between the lip and the fuselage skin should be clearly noticeable).

Step 3. Verify Hinge can travel freely with no restriction. Also verify you have enough travel to open your door. On most offset hinge brands, you should easily be able to get 90 degrees or more of rotation.
When you are happy with the hinge movement, glue it to the fuselage with epoxy and milled fibers. 5 minute Epoxy is ok.

Note: the key to good bonding is SURFACE PREPARATION. I scuff the fuselage area where the hinge will be glued, and the hinge base with 120 grit sandpaper. Then wipe down both faying surfaces with acetone. Use a thick drop of epoxy, enough to squeeze out. Then use your finger to create a nice fillet all around. If you have C-clamps, clamp the hinge to the fuselage.

Step 4. Repeat the same procedure for each hinge. Pay close attention to the hinge rotating freely, this is critical.

Step 5. Tape the gear door to the fuselage. The door should conform to the shape of the fuselage without any warping. If any warping exist, fix it first. I usually do this by taping the door to the fuselage, heat it with a heat gun, and leave it alone to cool overnight. I use 3" wide tape to cover the door completely before applying heat.

Step 6. With the door taped to the fuselage, roll the hinges away from the door and apply epoxy with milled fibers. Place a thick drop on each hinge base, enough to have a decent squeeze out. This epoxy bed will also serve as a shim between the hinge base and the gear door. This is due to the fact that on most models, the surface between the gear door and the fuselage skin will not be even, leaving a gap between the hinge base and the gear door.

Note: Do not force the hinge base flat into the gear door, it will only deform it and it will not operate "loosely". Rotate the hinge with glue on the base until it "touches" the gear door, then release and allow to cure.

Step 7. Allow Epoxy to cure, remove tape and verify that the door can rotate loosely. If you did it correctly, the door should have dropped immediately after the tape was removed. Check that the door travels enough to allow the landing gear to rotate without fouling.

Now seat back and admire your work of art.

Another hint. When the hinges are being glued to the door, you can tape the area between the door and the fuselage lip to prevent Epoxy from running into it and accidentally bonding the door to the fuselage.

After all of this is accomplish, you can now add screws if you wish to. I personally don't use them becasue in case of an accident I would prefer for the door to separate rather than tearing out part of the fuselage.

Any questions, feel free to shoot me a PM. Glad to help.

David

Exactly as I do it but in a brilliant tutorial, the CAD rendition is superb - I am sure all who see this will appreciate the time put in.

marcs

Great tutorial and much appreciated.

Thanks.

Gracias David,
Excelente trabajo y aclara muchas dudas del proceso.
Saludos
Norbert

Yep, thanks!![


But this tutorial came one week too late. I had my first geardoor experience last week

Nicely done

Thanks David - it doesn't get any clearer than that - really helpful

Bob

what cad program do you use ?? solid works??thanks for info.. great way to install hinges..[X(]

Excelente! Gracias

You just hit it out of the park...I copied the whole thing. Great job!!!

Mike

Great post - definitely a keeper !

Wow, David this could NOT have come at a better time!! Thank you SO much!!!

Pete

Hey David:

Thanks so much man.

Now please, a tutorial about door cylinder actuator installation and the right cylinder lenght selection.

I think this is more complicated that the gear door itself. To find the exact cylinder pivot position to get the right amount of door rotation is a mess.

On my F-16, although my new fuse I got at the end of 2.008 came with the gear doors installed (Not the gear itself because I kept it from my first F-16), I needed to trim a small amount of the right side fuse where the cylinder touch the it, for the door to open wide to avoid fouling with the wheel.

Thank you all for your compliments. All I hope for now is to hear success stories from you guys.
The software is CATIA v5 by Dassault (the real deal!).

If any of you have a model in work, please post pics of your progress!

Guillo, let me rest some and I will make a cylinder addendum.

Very nice and extremely professional presentation. Works well in real world application also.

Come on man.......you have 5 minutes....
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VERY NICE Dave
Thank you