Different types of landing gear

If you look at enough plans you will see lots of different types of landing gear.  On old designs sometimes the landing gear is sewn to the face of a bulkhead with soft wire and reinforced with epoxy.

sewLG

Sometimes it’s sewn to the bottom of a plywood bulkhead.  Or in the case of the Buzzard Bombshell from RCM, it’s shown on the bottom of the bulkhead and you’re supposed to figure out how to make it stay there.

buzzLG

When I built my Buzzard Bombshell I’m pretty sure I added little blocks to the bottom of these bulkheads and held the landing gear onto them with nylon landing gear straps.

A lot of designs from the 1960s through 1980s feature torque spring landing gear.  The gear legs are made of wire, with each side being bent from an independent piece of wire.  The left gear leg crosses the bottom of the fuselage and makes a 90 degree bend to go up through a hole in the right side, and vice versa.  The vertical members are held in place by hard wood blocks, so when the gear legs are deflected backwards the portion that crosses the bottom of the fuselage becomes a torque spring as it twists.

torqueLG

As you can see, there are lots of little parts in there, and it’s a lot easier to just replace the whole thing with a 1/8″ plywood chin and make a two-piece landing gear that’s soldered together near the axles, and attach it with inchworm style nylon straps, as shown on the plane in the photo below, which I built from the plan shown above.

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Another plan that shows a very inconvenient looking torque spring arrangement is the Wicked Wanda, shown in the following illustration.

wandaLG

Rather than build all of that, and figure out how to put a groove in a hard block, I stuck the block inside the plywood chin and left the landing gear wire totally on the outside of the plane.  Here’s what a plan would look like for the way I built my Wicked Wanda.

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The retaining strap is made from a tin can lid.  Here’s what the plane looks like.

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Open that photo in another window and zoom in on it.  You’ll notice that I cut a piece from a #64 rubber band (generally used for holding wings on) and placed it between the landing gear wires and the retaining straps.  This prevents vibration, which is sometimes a source of radio noise and may also loosen screws.  The rubber band creates a rattle-free installation.

Don’t get the idea that I don’t like building torque rods the way they’re shown on the plan.  Here’s another way to do it, from the Aerostar 20 plan.  The block has a groove in it.  The wire sits in the groove and is held in place with a piece of plywood.

Aero-StarLG

I made my block from three pieces of 1/8″ ply laminated together to form one 1/4″ block with a groove in it.  Then I covered it with a plywood retaining hatch as shown on the plan.

grooveblock

I like torque rods.  They are particularly good for trainers, planes that fly from rough fields, or anything that may take some abuse.  If your springs (legs) become weak, install new ones.  The only real disadvantage of torque spring landing gear is that when making a rough landing with a tail dragger, the wheels may be deflected far enough backward to cause a nose-over.  This problem is most common in tail draggers with wing mounted landing gear struts close to the center of gravity.  That’s why I prefer torque springs on nose wheel airplanes, and on tail draggers with the landing gear attached to the fuselage in front of the wing.

Some other landing gear designs shown on plans are pretty straightforward.  Sometimes you’re supposed to make a pair of landing gear legs and solder them together near the axle, and mount them to grooved blocks in the fuselage.

whimpLG

This is pretty easy to do, but if you don’t have grooved blocks you could theoretically cover the bottom of the fuselage with one or more layers of thin plywood and mount the gear with straps.  There’s no real advantage, but it’s a way to make use of whatever materials you have on hand.  In general, I think the two-piece soldered-together landing gear style is very durable and it has a classic look.  Plus you can make whatever shape you need, which is harder to do with manufactured landing gear.

Some plans show an aluminum landing gear attached to hard wood blocks using metal screws, such as this plan.

440LG

The plan above doesn’t show screws at all, but the one below shows metal screws.

BD-6-54in

Landing gear made from aluminum plate is one of the most popular types because it is so easy to install.  Unfortunately it acts as a spring in the vertical axis only.  Fore/aft stresses are transmitted almost entirely to the airframe.  If you want to add a bit of crash resistance, consider mounting your metal landing gear with nylon screws, like the ones in the following photo.

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For detailed instructions, refer to the article about mounting your wing with bolts and follow the exact same sequence.  Hold your gear in place, drill with the smaller bit through the landing gear and the hard wood block.  Tap threads in the wood, enlarge the hole in the landing gear, and mount the gear with the first screw.  Then drill the second hole.