How To/Make a Hinged Hatch

SMOOTH, CON­CEALED AC­CESS TO YOUR FUSELAGE

Model Airplane News - - CONTENTS - By Denny DeWeese

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.

A nicely fit­ting, pro­fes­sional-look­ing hatch and cover will do a great job of hid­ing all the RC hard­ware that would oth­er­wise dis­tract from the look of your scale air­craft.

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