Three types of gear
Piper Super Cub
Bungee cords (under metal fairings) protect Super Cubs from bounces on rough airstrips. But they only stretch so far, they're not easy to inspect, drips of oil from the engine compartment ruin them, and a break in a cord can result in a prop strike.
Cessna 180
Spring steel main landing gear on a Cessna 180 needs no maintenance and is strong and streamlined. But 180 gear are notoriously springy and tend to amplify bounces during wheel landings.
Aviat Husky
Aviat modified its original bungee-braced landing gear with internal, automotive shock absorbers in more recent models. If a bungee fails, the shock absorbers are meant to prevent a prop strike.
The landing gear in backcountry airplanes takes a lot of abuse. It’s got to be sturdy to stand up to the impact of touching down on rocky, muddy, or uneven terrain, and it must absorb the brunt of the impact without passing along too much force to the rest of the fragile airframe.
Traditionally, backcountry aircraft manufacturers have relied on low-tech elastic bands, rubber donuts, air- or oil-filled struts, or metal landing gear itself for this tough duty. A Piper PA–18 Super Cub’s main landing gear is typically held together by elastic bungee cords that stretch as the landing gear splays at touchdown. A Cessna 180 Skywagon has spring steel landing gear that bends outward to accomplish the same purpose. Both of those systems have been in place for decades.
Now, the popularity of snowmobiles, all-terrain vehicles, and off-road race cars has led to huge advancements in shock absorbers for vehicles that weigh about as much as small airplanes—and bush airplanes are among the beneficiaries.
Aviat added automotive shock absorbers to its Husky models. In the experimental category, Just Aircraft, Rans, and others offer an array of sophisticated shock absorbers for their STOL (short takeoff and landing) models.
Many backcountry airplanes are equipped with oversized tundra tires, and their inherently low tire pressure provides a cushion—and an enlarged footprint—for bearing weight on soft surfaces. But extreme conditions require more than soft tires. The Just Aircraft SuperSTOL, for example, uses long-stroke shock absorbers on its main landing gear and another, shorter version for the tailwheel.
Alpha Omega Suspension System (AOSS) replaces bungees in Super Cubs and some other FAA-certified aircraft, and Roberts Air Gear Extreme (RAGE) adjustable shock absorbers are retrofittable to a variety of aircraft. Unlike old-style metal gear or bungees, the RAGE system is adjustable, so pilots can make them stiffer or softer based on aircraft weight and the landing surface. As the popularity of backcountry airplanes increases, modern suspension systems allow these specialized aircraft to operate in even more extreme places.
