How To/Make a Hinged Hatch
SMOOTH, CONCEALED ACCESS TO YOUR FUSELAGE
Smooth, concealed access to your fuselage
One of the ways we can make our scale airplanes look more realistic is to hide any and all of the switches and other RC-related hardware so that they aren’t visible from the outside. Hatches and hatch covers are the answer, but you really need to do a good job so that the result is neat and professional looking. Let’s get to it.
1The tools we’ll need for this include a fine-tooth razor saw, a steeledge ruler, some Sullivan #517 yellow Nyrod, small pieces of 4-40 rod, a hatch latch (Bob Violett Models has the best), some fingernail files, and some masking tape. To create the hatches, you’ll need 1/32-inch and 1/8-inch plywood, Zap CA, Zap-a-Gap CA+, and 5-minute Z-Poxy.
Hide your RC hardware that distract from the look of your scale aircraft with an access hatch.
2Cut a piece of paper or cardstock to the same dimensions as the hatch, then lay out where the switches, fuel filler, air-line fillers, and charging leads will be installed. Leave enough room at the top, bottom, and each side for your hand to get in there. Plan all of this before you cut into the fuselage skin. Trace the cardstock template onto the side of the fuselage for the hatch location. Make sure that you position it away from bulkhead stations as cutting through bulkheads can be difficult.
3When it’s time to cut into the fuselage, tape a steel ruler in place to ensure that you cut a straight line. A fine-tooth razor saw is a great tool for this procedure. If the fuselage is built up from wood and fiberglass, penetrating the surface is fairly easy; however, if it is molded fiberglass or a composite, you will have to drag (pull) the saw blade along the edge of the ruler several times before the blade will penetrate the surface.
4Notice how cleanly the edges have been cut. The hatch opening has been cut on all four sides but not all the way. I left a little bit (1/8 inch) at each corner. To finish cutting into the corners, I used a clipped razor saw blade. If you don’t have this option and must use the full blade, just cut the edge slowly.
5Here you see the completed opening cut into place. Note here that I made this big opening on the right side of the model, which traditionally would not have any personal markings or fancy nose art.
6Now is the time to clean up the opening and the piece you removed so that they match nicely for a neat appearance. I use fingernail files for this. Then trial-fit the hatch cover to its opening. If you took your time while cutting, it should fit pretty well.
7Reinforce the ends of the hatch cover with some 1/8-inch plywood glued in place so that it will hold its shape.
8The pivot hinge is made out of a length of yellow Nyrod (#517) available from Sullivan. A 4-40 pushrod wire fits snuggly inside of it to act as the pivot rod. The best location for the hinge is about half an inch from the bottom of the hatch. Cut the yellow Nyrod to be longer than the hatch, and sand the outside of it to make it rough so that the 5-minute epoxy will properly adhere. Leave the Nyrod a bit long so that it can be trimmed exactly to length, and keep the epoxy out of the ends.
9Here is the picture of the inside of the fuselage. On the inside, I added a 1/32-inch plywood tongue at the top of the hatch opening to hold the hatch in place. Note that it is glued to the inside of the fuselage and not to the hatch.
10Here is an exploded view of the hinged area of the hatch. Before you glue the two Nyrod end pieces in place, trial-fit everything again to make sure that the hatch fits flush with the outside of the fuselage.
11With the 4-40 rod inserted, epoxy the two yellow end pieces to the fuselage on either side of the hatch. Here, I have used a small weight at the center of the hinge to hold the hatch exactly in place until the 5-minute epoxy cures. You will notice that a part of the 4-40 rod is sticking out to the right. This will allow you to pull it out (if necessary) to make any adjustments.
12At this point, you should be able to easily open and close the hatch. When it is closed, it should be flush and look like any other panel on the fuselage. Neatness while cutting pays off here.
13Next, mark the hatch where you wish to place the hatch latch. While many hatch latches will work, Frank Tiano and I use the best one we can find, which is manufactured by Bob Violett Models.
14Plot where the latch should go so that, when you pull back on the spring-loaded finger tab, the hatch will open properly. Use a mototool and a cutoff disc and make the slot in the hatch cover so that the finger tab fits easily through.
15When you’re positive everything fits perfectly, glue the assembly in place with some Zap glue. I used medium Zap CA+. Add a dab of glue on the ends of the yellow Nyrod end pieces so that the 4-40 wire won’t slide out of place. Use a moto-tool and a sanding drum to form a recess in the plywood support strip at the top of the hatch opening. This is so that the latch pin will secure the hatch cover snugly in place.
16Here is a shot of the RC hardware support plate that is glued in place under the hatch. It fits precisely and makes servicing your scale aircraft easy. Note that the lower edge of the plate is positioned so that the bottom of the hatch cover just touches it when the hatch is open. This supports the cover and helps prevent it from getting damaged by swinging down and resting on the outside of the fuselage. This same technique can be used with built-up wood aircraft; you simply have to take into account the positions of support formers and stringers that are under the skin. Make neat cuts, and if you have to, add some wood strips to the edges of the cover and sand to precisely fit the opening.