Photo: Icon Aircraft
Icon Aircraft has made aviation history even before finishing the final design of its first airplane.
The company hit a significant milestone in the development of its A5 amphibious light sport aircraft with a wing design aimed at significantly improving safety. The company has completed a rigorous flight testing schedule focused on the stall and spin characteristics of the two-seater, and when the first plane rolls off the line it will become the first production aircraft to comply completely with FAA spin resistance standards. In simpler terms, Icon has designed an airplane that could practically erase one of the major causes of aviation accidents.
“Creating a full-envelope spin-resistant airplane was extraordinarily difficult and took longer than expected,” CEO Kirk Hawkins said today in a statement announcing FAA certification of the wing. “[The design] dramatically raises the bar for light aircraft safety by decreasing the likelihood of inadvertent stall/spin loss of control by the pilot.”
Many production airplane designs have over the years made significant progress toward minimizing the chance of a stall/spin accident. Until now, however, no airplane has been produced that fully complies with what is known as the Federal Aviation Administration’s Part 23 spin-resistance standards. When the first A5 rolls off the factory floor, it will benefit from decades of NASA and FAA research focused on reducing, or even eliminating, accidents due to the inadvertent stall/spin. The spin-resistant design doesn’t eliminate all potential hazards, but much like anti-lock brakes in automobiles, it dramatically decreases a big hazard.
The boom off of the back of the airplane contains a parachute and is commonly used in spin testing. The production A5 will have a parachute, but it will be integrated into the airframe. The small lines on the airplane are tufts of yarn that allow engineers to see how the air is flowing around the airframe.
An inadvertent stall/spin refers to a scenario in which a pilot unintentionally flies the airplane in a manner that disrupts airflow over the wing so severely it cannot produce sufficient lift. This usually happens at lower speeds, though it is related to the “angle of attack” of the wing and not necessarily airspeed. When the airflow disruption occurs, the wing is said to be in a “stalled” condition and the airplane begins to lose altitude due to the loss of lift. Once a wing is stalled, the aircraft can enter a spin if there is sufficient yaw motion (turning in the horizontal plane.).
If an airplane simply enters a stall and the pilot makes the necessary corrections taught during training, minimal altitude may be lost before the wing can generate sufficient lift to resume flight. But if the airplane enters a spin, significantly more altitude is lost. Although a pilot can recover from a spin (usually with specific training, see video below), the resulting disorientation often makes recovery less likely. Two common scenarios where this may occur are when the pilot is making a final turn before lining up with the runway to land, or turning back to the runway after taking off if an emergency landing is required.
Inadvertent stall/spin accidents account for a significant percentage of pilot-related accidents in non-commercial general aviation, according to a report from the Aircraft Owners and Pilots Association.
By designing the A5 to be highly resistant to entering a spin, Icon provides pilots with an extra margin of safety should they manage to stall the wings. Hawkins says the A5 will provide “excellent control throughout the stall.”
Many of the small, general aviation aircraft flown today are approved for practicing spins and can safely recover assuming the pilot has the proper training. But even in a perfect scenario the recovery may use up well over 500 feet — which can be a problem if you’re below that altitude to begin, as you might be during landing. Airshow pilots are always aware of the altitude needed to recover from a spin, though they often find themselves in more complex versions including inverted spins.
Rich Stowell is one of the foremost experts in stall/spin safety and has performed more than 32,000 spins in dozens of aircraft. In his book Stall/Spin Awareness, he notes the “specter of an inadvertent stall/spin can affect a pilot’s passion for flying.” Stowell is a proponent of pilots learning about the stall/spin and has taught countless pilots how to recognize and recover from many types of scenarios.
Stowell’s training focus is aimed at pilots flying most existing airplane designs that are safe, though not necessarily spin resistant. Icon wants to eliminate that specter for the wider range of potential pilots it hopes to attract to aviation.
Since its inception, Icon has focused on developing an airplane that will draw more people to flying. By practically eliminating the specter of the stall/spin, Icon should have an advantage when talking to newcomers who may have limited knowledge of the matter and want an airplane that is as safe as possible.
Other recent general aviation aircraft designs including the Cirrus SR20/22 and the Cessna Corvalis (formerly Columbia 350/400) incorporate similar design improvements aimed at spin resistance. These airplanes, especially the Cirrus, also are aimed at attracting non-pilots to aviation. While both airplanes have better spin resistance than traditional designs, neither completely fulfilled Part 23 standards. One airplane, the canard-equipped Jetcruzer, met the FAA’s testing requirements but never saw production.
The new wing cuff is visible on the leading edge of the A5 prototype.
To complete the flights in order to satisfy the FAA, Icon hired a test pilot who specializes in spin testing aircraft. More than 360 test cases were flown in recent months with the prototype aircraft covering a wide range of possible spin scenarios. The new wing includes a cuff on the leading edge that results in air flowing properly over parts of the wing where the controls are located even when other parts of the wing are stalled.
Hawkins told Wired.com spin testing is never taken lightly, even with thorough design testing and engineering. Aviation giant Cessna lost two airplanes during the spin testing of its light sport aircraft design, the 162 Skycatcher. In both cases the test pilots were able to parachute safely to the ground.
“It’s the most tricky part of the flight test envelope,” he said.
Hawkins said the design of the A5 is nearing completion. With stall/spin testing complete, the exterior of the airframe is unlikely to change. Development of the first production aircraft is in full swing at the company’s southern California facilities, and Icon is hoping to begin flight testing of the first production model “soon.”
The Icon A5 is capable of landing on both land and water and the wings can be folded via an automatic electric system allowing it to be parked in a garage and towed on a trailer to a lake or airport. The company has several hundred aircraft already on order and is scheduled to begin production this year.
Photos: Icon Aircraft, Video: mtcaving/YouTube
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