Techinque of the month

Model Airplane News, Jun 2000 by Leu, George

ARTICULATED GEAR-DOOR STANDOFFS

Although I have slightly modified it to suit my own applications, this technique comes from Bruce Saunders of Century Jet Models*. Standoffs are those little tubes or other attachments that connect the gear doors to the retractable landinggear struts. These devices pull and push the gear doors to open and close them when the Landing gear extends and retracts.

For years, I bent lengths at wire to use as standoffs; it was difficult to get them just the right length to pull my gear doors tightly into place when the gear strut retracted; in fact, this often took more time than it did to install the retracts themselves. Using solid wire poses problems because the angle and distance between the door hinge and the gear strut change when the gear moves. Bruce's method is much easier. Let's try it.

1. Cut two 1-inch lengths of brass tube (I recommend 1/8-inch: and 3/16-inchdiameter tubes), and insert the narrower tube into the wider one. Cut a 3-inch piece of rubber band and slip it through the tubes. Pull the narrower tube out of the other by 3/4 inch and crimp about 1/4 inch of its end to trap the rubber band. Try to keep the rubber band to one side as you crimp the tube's end.

2. Pull the other end of the rubber band tight and crimp the outer tube's end as you did to the inner one. Do not stretch the rubber band too tightly-only enough to keep tension on the tubes when you let go.

3. Drill a 1/16-inch hole in each tube's crimped end and attach the standoff to attach the door and gear strut. Attach one end of the standoff to the gear door with a small attachment bracket; secure its other to the gear strut with a small machine screw. You'll have to drill and tap a small hole in the strut to attach the screw. And that's it! When the gear is in the down position, the gear door is supported by its hinge at the top and by the end of the standoff tube. When the gear retracts, the door is pulled shut, and the stand-off self-adjusts to the exact length needed to keep the door closed tightly. The rubber band keeps tension on the door so it will not blow open during flight.

Give this technique a try; it will make everyone think you spend an enormous length of time adjusting the door linkage. Go ahead; I won't tell anyone!